From 5c92dec542268d5ddb4eb99bc90105241cb0809f Mon Sep 17 00:00:00 2001
From: Glenn Randers-Pehrson <glennrp at users.sourceforge.net>
Date: Fri, 7 Jan 2011 18:28:47 -0600
Subject: [PATCH] [devel] The wrong pngrutil.c (version 1.4.1) was checked in.

---
 pngrutil.c | 1628 ++++++++++++++++++++++++++++++----------------------
 1 file changed, 931 insertions(+), 697 deletions(-)

diff --git a/pngrutil.c b/pngrutil.c
index e29fc6f3b..926e23632 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -1,8 +1,8 @@
 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.4.1 [February 8, 2010]
- * Copyright (c) 1998-2010 Glenn Randers-Pehrson
+ * Last changed in libpng 1.5.0 [January 6, 2011]
+ * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -14,59 +14,136 @@
  * libpng itself during the course of reading an image.
  */
 
-#define PNG_INTERNAL
-#define PNG_NO_PEDANTIC_WARNINGS
-#include "png.h"
-#ifdef PNG_READ_SUPPORTED
 #include "pngpriv.h"
 
-#    define png_strtod(p,a,b) strtod(a,b)
-png_uint_32 PNGAPI
-png_get_uint_31(png_structp png_ptr, png_bytep buf)
-{
-   png_uint_32 i = png_get_uint_32(buf);
-   if (i > PNG_UINT_31_MAX)
-     png_error(png_ptr, "PNG unsigned integer out of range");
-   return (i);
-}
-#ifndef PNG_USE_READ_MACROS
-/* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
-png_uint_32 PNGAPI
-png_get_uint_32(png_bytep buf)
-{
-   png_uint_32 i = ((png_uint_32)(*buf) << 24) +
-      ((png_uint_32)(*(buf + 1)) << 16) +
-      ((png_uint_32)(*(buf + 2)) << 8) +
-      (png_uint_32)(*(buf + 3));
+#ifdef PNG_READ_SUPPORTED
 
-   return (i);
+#define png_strtod(p,a,b) strtod(a,b)
+
+png_uint_32 PNGAPI
+png_get_uint_31(png_structp png_ptr, png_const_bytep buf)
+{
+   png_uint_32 uval = png_get_uint_32(buf);
+
+   if (uval > PNG_UINT_31_MAX)
+      png_error(png_ptr, "PNG unsigned integer out of range");
+
+   return (uval);
+}
+
+#if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)
+/* The following is a variation on the above for use with the fixed
+ * point values used for gAMA and cHRM.  Instead of png_error it
+ * issues a warning and returns (-1) - an invalid value because both
+ * gAMA and cHRM use *unsigned* integers for fixed point values.
+ */
+#define PNG_FIXED_ERROR (-1)
+
+static png_fixed_point /* PRIVATE */
+png_get_fixed_point(png_structp png_ptr, png_const_bytep buf)
+{
+   png_uint_32 uval = png_get_uint_32(buf);
+
+   if (uval <= PNG_UINT_31_MAX)
+      return (png_fixed_point)uval; /* known to be in range */
+
+   /* The caller can turn off the warning by passing NULL. */
+   if (png_ptr != NULL)
+      png_warning(png_ptr, "PNG fixed point integer out of range");
+
+   return PNG_FIXED_ERROR;
+}
+#endif
+
+#ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
+/* NOTE: the read macros will obscure these definitions, so that if
+ * PNG_USE_READ_MACROS is set the library will not use them internally,
+ * but the APIs will still be available externally.
+ *
+ * The parentheses around "PNGAPI function_name" in the following three
+ * functions are necessary because they allow the macros to co-exist with
+ * these (unused but exported) functions.
+ */
+
+/* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
+png_uint_32 (PNGAPI
+png_get_uint_32)(png_const_bytep buf)
+{
+   png_uint_32 uval =
+       ((png_uint_32)(*(buf    )) << 24) +
+       ((png_uint_32)(*(buf + 1)) << 16) +
+       ((png_uint_32)(*(buf + 2)) <<  8) +
+       ((png_uint_32)(*(buf + 3))      ) ;
+
+   return uval;
 }
 
 /* Grab a signed 32-bit integer from a buffer in big-endian format.  The
- * data is stored in the PNG file in two's complement format, and it is
- * assumed that the machine format for signed integers is the same.
+ * data is stored in the PNG file in two's complement format and there
+ * is no guarantee that a 'png_int_32' is exactly 32 bits, therefore
+ * the following code does a two's complement to native conversion.
  */
-png_int_32 PNGAPI
-png_get_int_32(png_bytep buf)
+png_int_32 (PNGAPI
+png_get_int_32)(png_const_bytep buf)
 {
-   png_int_32 i = ((png_int_32)(*buf) << 24) +
-      ((png_int_32)(*(buf + 1)) << 16) +
-      ((png_int_32)(*(buf + 2)) << 8) +
-      (png_int_32)(*(buf + 3));
+   png_uint_32 uval = png_get_uint_32(buf);
+   if ((uval & 0x80000000L) == 0) /* non-negative */
+      return uval;
 
-   return (i);
+   uval = (uval ^ 0xffffffffL) + 1;  /* 2's complement: -x = ~x+1 */
+   return -(png_int_32)uval;
 }
 
 /* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
-png_uint_16 PNGAPI
-png_get_uint_16(png_bytep buf)
+png_uint_16 (PNGAPI
+png_get_uint_16)(png_const_bytep buf)
 {
-   png_uint_16 i = (png_uint_16)(((png_uint_16)(*buf) << 8) +
-      (png_uint_16)(*(buf + 1)));
+   /* ANSI-C requires an int value to accomodate at least 16 bits so this
+    * works and allows the compiler not to worry about possible narrowing
+    * on 32 bit systems.  (Pre-ANSI systems did not make integers smaller
+    * than 16 bits either.)
+    */
+   unsigned int val =
+       ((unsigned int)(*buf) << 8) +
+       ((unsigned int)(*(buf + 1)));
 
-   return (i);
+   return (png_uint_16)val;
+}
+
+#endif /* PNG_READ_INT_FUNCTIONS_SUPPORTED */
+
+/* Read and check the PNG file signature */
+void /* PRIVATE */
+png_read_sig(png_structp png_ptr, png_infop info_ptr)
+{
+   png_size_t num_checked, num_to_check;
+
+   /* Exit if the user application does not expect a signature. */
+   if (png_ptr->sig_bytes >= 8)
+      return;
+
+   num_checked = png_ptr->sig_bytes;
+   num_to_check = 8 - num_checked;
+
+#ifdef PNG_IO_STATE_SUPPORTED
+   png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
+#endif
+
+   /* The signature must be serialized in a single I/O call. */
+   png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
+   png_ptr->sig_bytes = 8;
+
+   if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
+   {
+      if (num_checked < 4 &&
+          png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
+         png_error(png_ptr, "Not a PNG file");
+      else
+         png_error(png_ptr, "PNG file corrupted by ASCII conversion");
+   }
+   if (num_checked < 3)
+      png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
 }
-#endif /* PNG_USE_READ_MACROS */
 
 /* Read the chunk header (length + type name).
  * Put the type name into png_ptr->chunk_name, and return the length.
@@ -78,33 +155,29 @@ png_read_chunk_header(png_structp png_ptr)
    png_uint_32 length;
 
 #ifdef PNG_IO_STATE_SUPPORTED
-   /* Inform the I/O callback that the chunk header is being read.
-    * PNG_IO_CHUNK_HDR requires a single I/O call.
-    */
    png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
 #endif
 
-   /* Read the length and the chunk name */
+   /* Read the length and the chunk name.
+    * This must be performed in a single I/O call.
+    */
    png_read_data(png_ptr, buf, 8);
    length = png_get_uint_31(png_ptr, buf);
 
-   /* Put the chunk name into png_ptr->chunk_name */
+   /* Put the chunk name into png_ptr->chunk_name. */
    png_memcpy(png_ptr->chunk_name, buf + 4, 4);
 
-   png_debug2(0, "Reading %s chunk, length = %lu",
-      png_ptr->chunk_name, length);
+   png_debug2(0, "Reading %s chunk, length = %u",
+       png_ptr->chunk_name, length);
 
-   /* Reset the crc and run it over the chunk name */
+   /* Reset the crc and run it over the chunk name. */
    png_reset_crc(png_ptr);
    png_calculate_crc(png_ptr, png_ptr->chunk_name, 4);
 
-   /* Check to see if chunk name is valid */
+   /* Check to see if chunk name is valid. */
    png_check_chunk_name(png_ptr, png_ptr->chunk_name);
 
 #ifdef PNG_IO_STATE_SUPPORTED
-   /* Inform the I/O callback that chunk data will (possibly) be read.
-    * PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.
-    */
    png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
 #endif
 
@@ -117,6 +190,7 @@ png_crc_read(png_structp png_ptr, png_bytep buf, png_size_t length)
 {
    if (png_ptr == NULL)
       return;
+
    png_read_data(png_ptr, buf, length);
    png_calculate_crc(png_ptr, buf, length);
 }
@@ -136,6 +210,7 @@ png_crc_finish(png_structp png_ptr, png_uint_32 skip)
    {
       png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
    }
+
    if (i)
    {
       png_crc_read(png_ptr, png_ptr->zbuf, i);
@@ -150,11 +225,13 @@ png_crc_finish(png_structp png_ptr, png_uint_32 skip)
       {
          png_chunk_warning(png_ptr, "CRC error");
       }
+
       else
       {
          png_chunk_benign_error(png_ptr, "CRC error");
          return (0);
       }
+
       return (1);
    }
 
@@ -177,6 +254,7 @@ png_crc_error(png_structp png_ptr)
           (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
          need_crc = 0;
    }
+
    else                                                    /* critical */
    {
       if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
@@ -184,11 +262,10 @@ png_crc_error(png_structp png_ptr)
    }
 
 #ifdef PNG_IO_STATE_SUPPORTED
-   /* Inform the I/O callback that the chunk CRC is being read */
-   /* PNG_IO_CHUNK_CRC requires the I/O to be done at once */
    png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
 #endif
 
+   /* The chunk CRC must be serialized in a single I/O call. */
    png_read_data(png_ptr, crc_bytes, 4);
 
    if (need_crc)
@@ -196,76 +273,144 @@ png_crc_error(png_structp png_ptr)
       crc = png_get_uint_32(crc_bytes);
       return ((int)(crc != png_ptr->crc));
    }
+
    else
       return (0);
 }
 
 #if defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) || \
     defined(PNG_READ_iCCP_SUPPORTED)
-png_size_t
-png_measure_decompressed_chunk(png_structp png_ptr, int comp_type,
-    png_size_t chunklength, png_size_t prefix_size)
+static png_size_t
+png_inflate(png_structp png_ptr, png_bytep data, png_size_t size,
+    png_bytep output, png_size_t output_size)
 {
-   png_charp text;
-   png_charp test = "X";
-   png_size_t text_size = 0;
+   png_size_t count = 0;
 
-   if (comp_type == PNG_COMPRESSION_TYPE_BASE)
+   /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it can't
+    * even necessarily handle 65536 bytes) because the type uInt is "16 bits or
+    * more".  Consequently it is necessary to chunk the input to zlib.  This
+    * code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the maximum value
+    * that can be stored in a uInt.)  It is possible to set ZLIB_IO_MAX to a
+    * lower value in pngpriv.h and this may sometimes have a performance
+    * advantage, because it forces access of the input data to be separated from
+    * at least some of the use by some period of time.
+    */
+   png_ptr->zstream.next_in = data;
+   /* avail_in is set below from 'size' */
+   png_ptr->zstream.avail_in = 0;
+
+   while (1)
    {
-      int ret = Z_OK;
+      int ret, avail;
 
-      png_ptr->zstream.next_in = (png_bytep)(png_ptr->chunkdata + prefix_size);
-      png_ptr->zstream.avail_in = (uInt)(chunklength - prefix_size);
-      png_ptr->zstream.next_out = png_ptr->zbuf;
-      png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
-
-      text = NULL;
-
-      while (png_ptr->zstream.avail_in)
+      /* The setting of 'avail_in' used to be outside the loop, by setting it
+       * inside it is possible to chunk the input to zlib and simply rely on
+       * zlib to advance the 'next_in' pointer.  This allows arbitrary amounts o
+       * data to be passed through zlib at the unavoidable cost of requiring a
+       * window save (memcpy of up to 32768 output bytes) every ZLIB_IO_MAX
+       * input bytes.
+       */
+      if (png_ptr->zstream.avail_in == 0 && size > 0)
       {
-         ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
-         if (ret != Z_OK && ret != Z_STREAM_END)
+         if (size <= ZLIB_IO_MAX)
          {
-            inflateReset(&png_ptr->zstream);
-            png_ptr->zstream.avail_in = 0;
-            break;
+            /* The value is less than ZLIB_IO_MAX so the cast is safe: */
+            png_ptr->zstream.avail_in = (uInt)size;
+            size = 0;
          }
-         if (!png_ptr->zstream.avail_out || ret == Z_STREAM_END)
-         {
-            if (text == NULL)  /* Initialize the decompression buffer */
-            {
-               text_size = prefix_size +
-                   png_ptr->zbuf_size - png_ptr->zstream.avail_out;
-
-               text=test;
-            }
-            else               /* Enlarge the decompression buffer */
-            {
-              text_size += png_ptr->zbuf_size - png_ptr->zstream.avail_out;
-#ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
-              if (png_ptr->user_chunk_malloc_max &&
-                  (text_size >= png_ptr->user_chunk_malloc_max - 1))
-#else
-              if ((PNG_USER_CHUNK_MALLOC_MAX > 0) &&
-                  text_size >= PNG_USER_CHUNK_MALLOC_MAX - 1)
-#endif
-                 return 0;
-            }
-         }
-         if (ret == Z_STREAM_END)
-            break;
 
          else
          {
-            png_ptr->zstream.next_out = png_ptr->zbuf;
-            png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
+            png_ptr->zstream.avail_in = ZLIB_IO_MAX;
+            size -= ZLIB_IO_MAX;
          }
       }
 
-      inflateReset(&png_ptr->zstream);
+      /* Reset the output buffer each time round - we empty it
+       * after every inflate call.
+       */
+      png_ptr->zstream.next_out = png_ptr->zbuf;
+      png_ptr->zstream.avail_out = png_ptr->zbuf_size;
+
+      ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
+      avail = png_ptr->zbuf_size - png_ptr->zstream.avail_out;
+
+      /* First copy/count any new output - but only if we didn't
+       * get an error code.
+       */
+      if ((ret == Z_OK || ret == Z_STREAM_END) && avail > 0)
+      {
+         png_size_t space = avail; /* > 0, see above */
+
+         if (output != 0 && output_size > count)
+         {
+            png_size_t copy = output_size - count;
+
+            if (space < copy)
+               copy = space;
+
+            png_memcpy(output + count, png_ptr->zbuf, copy);
+         }
+         count += space;
+      }
+
+      if (ret == Z_OK)
+         continue;
+
+      /* Termination conditions - always reset the zstream, it
+       * must be left in inflateInit state.
+       */
       png_ptr->zstream.avail_in = 0;
+      inflateReset(&png_ptr->zstream);
+
+      if (ret == Z_STREAM_END)
+         return count; /* NOTE: may be zero. */
+
+      /* Now handle the error codes - the API always returns 0
+       * and the error message is dumped into the uncompressed
+       * buffer if available.
+       */
+      {
+         PNG_CONST char *msg;
+#ifdef PNG_CONSOLE_IO_SUPPORTED
+         char umsg[52];
+#endif
+         if (png_ptr->zstream.msg != 0)
+            msg = png_ptr->zstream.msg;
+
+         else
+         {
+#ifdef PNG_CONSOLE_IO_SUPPORTED
+            switch (ret)
+            {
+               case Z_BUF_ERROR:
+                  msg = "Buffer error in compressed datastream in %s chunk";
+                  break;
+
+               case Z_DATA_ERROR:
+                  msg = "Data error in compressed datastream in %s chunk";
+                  break;
+
+               default:
+                  msg = "Incomplete compressed datastream in %s chunk";
+                  break;
+            }
+
+            png_snprintf(umsg, sizeof umsg, msg, png_ptr->chunk_name);
+            msg = umsg;
+#else
+            msg = "Damaged compressed datastream in chunk other than IDAT";
+#endif
+         }
+
+         png_warning(png_ptr, msg);
+      }
+
+      /* 0 means an error - notice that this code simply ignores
+       * zero length compressed chunks as a result.
+       */
+      return 0;
    }
-   return text_size;
 }
 
 /*
@@ -280,164 +425,116 @@ png_decompress_chunk(png_structp png_ptr, int comp_type,
     png_size_t chunklength,
     png_size_t prefix_size, png_size_t *newlength)
 {
-   static PNG_CONST char msg[] = "Error decoding compressed chunk";
-   png_charp text;
-   png_size_t text_size;
-   png_size_t expanded_size;
-
-   expanded_size= png_measure_decompressed_chunk(png_ptr, comp_type,
-      chunklength, prefix_size);
-   if (expanded_size == 0)
+   /* The caller should guarantee this */
+   if (prefix_size > chunklength)
    {
-      *newlength=0;
-      return;
+      /* The recovery is to delete the chunk. */
+      png_warning(png_ptr, "invalid chunklength");
+      prefix_size = 0; /* To delete everything */
    }
 
-   if (comp_type == PNG_COMPRESSION_TYPE_BASE)
+   else if (comp_type == PNG_COMPRESSION_TYPE_BASE)
    {
-      int ret = Z_OK;
-      png_size_t buffer_size;
+      png_size_t expanded_size = png_inflate(png_ptr,
+          (png_bytep)(png_ptr->chunkdata + prefix_size),
+          chunklength - prefix_size,
+          0,            /*output*/
+          0);           /*output size*/
 
-      png_ptr->zstream.next_in = (png_bytep)(png_ptr->chunkdata + prefix_size);
-      png_ptr->zstream.avail_in = (uInt)(chunklength - prefix_size);
-      png_ptr->zstream.next_out = png_ptr->zbuf;
-      png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
-
-      text_size = 0;
-      text = NULL;
-      buffer_size = 0;
-
-      while (png_ptr->zstream.avail_in)
-      {
-         ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
-         if (ret != Z_OK && ret != Z_STREAM_END)
-         {
-            if (png_ptr->zstream.msg != NULL)
-               png_warning(png_ptr, png_ptr->zstream.msg);
-            else
-               png_warning(png_ptr, msg);
-            inflateReset(&png_ptr->zstream);
-            png_ptr->zstream.avail_in = 0;
-
-            if (text ==  NULL)
-            {
-               text_size = prefix_size + png_sizeof(msg) + 1;
-               text = (png_charp)png_malloc_warn(png_ptr, text_size);
-               if (text ==  NULL)
-               {
-                  png_error(png_ptr,
-                     "Not enough memory to decompress chunk");
-                  text_size = 0;
-                  break;
-               }
-               png_memcpy(text, png_ptr->chunkdata, prefix_size);
-            }
-
-            text[text_size - 1] = 0x00;
-
-            /* Copy what we can of the error message into the text chunk */
-            text_size = (png_size_t)(chunklength -
-                (text - png_ptr->chunkdata) - 1);
-
-            if (text_size > png_sizeof(msg))
-               text_size = png_sizeof(msg);
-
-            png_memcpy(text + prefix_size, msg, text_size);
-            buffer_size = text_size;
-            break;
-         }
-         if (!png_ptr->zstream.avail_out || ret == Z_STREAM_END)
-         {
-            if (text == NULL)  /* Initialize the decompression buffer */
-            {
-               text_size = expanded_size;
-
-               text = (png_charp)png_malloc_warn(png_ptr, text_size + 1);
-               if (text ==  NULL)
-               {
-                  png_error(png_ptr,
-                    "Not enough memory to decompress chunk");
-                  text_size = 0;
-                  break;
-               }
-               png_memcpy(text + prefix_size, png_ptr->zbuf,
-                    text_size - prefix_size);
-               png_memcpy(text, png_ptr->chunkdata, prefix_size);
-               *(text + text_size) = 0x00;
-               buffer_size = text_size;
-            }
-         }
-         if (ret == Z_STREAM_END)
-            break;
-
-         else
-         {
-            png_ptr->zstream.next_out = png_ptr->zbuf;
-            png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
-         }
-      }
-
-      if (ret != Z_STREAM_END)
-      {
-#ifdef PNG_STDIO_SUPPORTED
-         char umsg[52];
-
-         if (ret == Z_BUF_ERROR)
-            png_snprintf(umsg, 52,
-                "Buffer error in compressed datastream in %s chunk",
-                png_ptr->chunk_name);
-
-         else if (ret == Z_DATA_ERROR)
-            png_snprintf(umsg, 52,
-                "Data error in compressed datastream in %s chunk",
-                png_ptr->chunk_name);
-
-         else
-            png_snprintf(umsg, 52,
-                "Incomplete compressed datastream in %s chunk",
-                png_ptr->chunk_name);
-
-         png_warning(png_ptr, umsg);
+      /* Now check the limits on this chunk - if the limit fails the
+       * compressed data will be removed, the prefix will remain.
+       */
+#ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
+      if (png_ptr->user_chunk_malloc_max &&
+          (prefix_size + expanded_size >= png_ptr->user_chunk_malloc_max - 1))
 #else
-         png_warning(png_ptr,
-            "Incomplete compressed datastream in chunk other than IDAT");
+#  ifdef PNG_USER_CHUNK_MALLOC_MAX
+      if ((PNG_USER_CHUNK_MALLOC_MAX > 0) &&
+          prefix_size + expanded_size >= PNG_USER_CHUNK_MALLOC_MAX - 1)
+#  endif
 #endif
-         text_size = prefix_size;
-         if (text ==  NULL)
+         png_warning(png_ptr, "Exceeded size limit while expanding chunk");
+
+      /* If the size is zero either there was an error and a message
+       * has already been output (warning) or the size really is zero
+       * and we have nothing to do - the code will exit through the
+       * error case below.
+       */
+#if defined(PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED) || \
+    defined(PNG_USER_CHUNK_MALLOC_MAX)
+      else if (expanded_size > 0)
+#else
+      if (expanded_size > 0)
+#endif
+      {
+         /* Success (maybe) - really uncompress the chunk. */
+         png_size_t new_size = 0;
+         png_charp text = png_malloc_warn(png_ptr,
+             prefix_size + expanded_size + 1);
+
+         if (text != NULL)
          {
-            text = (png_charp)png_malloc_warn(png_ptr, text_size+1);
-            if (text == NULL)
+            png_memcpy(text, png_ptr->chunkdata, prefix_size);
+            new_size = png_inflate(png_ptr,
+                (png_bytep)(png_ptr->chunkdata + prefix_size),
+                chunklength - prefix_size,
+                (png_bytep)(text + prefix_size), expanded_size);
+            text[prefix_size + expanded_size] = 0; /* just in case */
+
+            if (new_size == expanded_size)
             {
                png_free(png_ptr, png_ptr->chunkdata);
-               png_ptr->chunkdata = NULL;
-               png_error(png_ptr, "Not enough memory for text");
+               png_ptr->chunkdata = text;
+               *newlength = prefix_size + expanded_size;
+               return; /* The success return! */
             }
-            png_memcpy(text, png_ptr->chunkdata, prefix_size);
+
+            png_warning(png_ptr, "png_inflate logic error");
+            png_free(png_ptr, text);
          }
-         *(text + text_size) = 0x00;
+
+         else
+            png_warning(png_ptr, "Not enough memory to decompress chunk");
       }
-
-      inflateReset(&png_ptr->zstream);
-      png_ptr->zstream.avail_in = 0;
-
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = text;
-      *newlength=text_size;
    }
+
    else /* if (comp_type != PNG_COMPRESSION_TYPE_BASE) */
    {
 #ifdef PNG_STDIO_SUPPORTED
       char umsg[50];
 
-      png_snprintf(umsg, 50, "Unknown zTXt compression type %d", comp_type);
+      png_snprintf(umsg, sizeof umsg,
+          "Unknown zTXt compression type %d", comp_type);
       png_warning(png_ptr, umsg);
 #else
       png_warning(png_ptr, "Unknown zTXt compression type");
 #endif
 
-      *(png_ptr->chunkdata + prefix_size) = 0x00;
-      *newlength = prefix_size;
+      /* The recovery is to simply drop the data. */
    }
+
+   /* Generic error return - leave the prefix, delete the compressed
+    * data, reallocate the chunkdata to remove the potentially large
+    * amount of compressed data.
+    */
+   {
+      png_charp text = png_malloc_warn(png_ptr, prefix_size + 1);
+
+      if (text != NULL)
+      {
+         if (prefix_size > 0)
+            png_memcpy(text, png_ptr->chunkdata, prefix_size);
+
+         png_free(png_ptr, png_ptr->chunkdata);
+         png_ptr->chunkdata = text;
+
+         /* This is an extra zero in the 'uncompressed' part. */
+         *(png_ptr->chunkdata + prefix_size) = 0x00;
+      }
+      /* Ignore a malloc error here - it is safe. */
+   }
+
+   *newlength = prefix_size;
 }
 #endif
 
@@ -486,6 +583,7 @@ png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    /* Find number of channels */
    switch (png_ptr->color_type)
    {
+      default: /* invalid, png_set_IHDR calls png_error */
       case PNG_COLOR_TYPE_GRAY:
       case PNG_COLOR_TYPE_PALETTE:
          png_ptr->channels = 1;
@@ -510,9 +608,9 @@ png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
    png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
    png_debug1(3, "channels = %d", png_ptr->channels);
-   png_debug1(3, "rowbytes = %lu", png_ptr->rowbytes);
+   png_debug1(3, "rowbytes = %u", png_ptr->rowbytes);
    png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
-      color_type, interlace_type, compression_type, filter_type);
+       color_type, interlace_type, compression_type, filter_type);
 }
 
 /* Read and check the palette */
@@ -545,10 +643,11 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
    {
       png_warning(png_ptr,
-        "Ignoring PLTE chunk in grayscale PNG");
+          "Ignoring PLTE chunk in grayscale PNG");
       png_crc_finish(png_ptr, length);
       return;
    }
+
 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
    if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
    {
@@ -597,7 +696,7 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 #endif
 
-   /* If we actually NEED the PLTE chunk (ie for a paletted image), we do
+   /* If we actually need the PLTE chunk (ie for a paletted image), we do
     * whatever the normal CRC configuration tells us.  However, if we
     * have an RGB image, the PLTE can be considered ancillary, so
     * we will act as though it is.
@@ -608,25 +707,29 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    {
       png_crc_finish(png_ptr, 0);
    }
+
 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
    else if (png_crc_error(png_ptr))  /* Only if we have a CRC error */
    {
       /* If we don't want to use the data from an ancillary chunk,
-         we have two options: an error abort, or a warning and we
-         ignore the data in this chunk (which should be OK, since
-         it's considered ancillary for a RGB or RGBA image). */
+       * we have two options: an error abort, or a warning and we
+       * ignore the data in this chunk (which should be OK, since
+       * it's considered ancillary for a RGB or RGBA image).
+       */
       if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))
       {
          if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
          {
             png_chunk_benign_error(png_ptr, "CRC error");
          }
+
          else
          {
             png_chunk_warning(png_ptr, "CRC error");
             return;
          }
       }
+
       /* Otherwise, we (optionally) emit a warning and use the chunk. */
       else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN))
       {
@@ -647,6 +750,7 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
             png_warning(png_ptr, "Truncating incorrect tRNS chunk length");
             png_ptr->num_trans = (png_uint_16)num;
          }
+
          if (info_ptr->num_trans > (png_uint_16)num)
          {
             png_warning(png_ptr, "Truncating incorrect info tRNS chunk length");
@@ -674,9 +778,10 @@ png_handle_IEND(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    {
       png_warning(png_ptr, "Incorrect IEND chunk length");
    }
+
    png_crc_finish(png_ptr, length);
 
-   info_ptr = info_ptr; /* Quiet compiler warnings about unused info_ptr */
+   PNG_UNUSED(info_ptr) /* Quiet compiler warnings about unused info_ptr */
 }
 
 #ifdef PNG_READ_gAMA_SUPPORTED
@@ -684,30 +789,29 @@ void /* PRIVATE */
 png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_fixed_point igamma;
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   float file_gamma;
-#endif
    png_byte buf[4];
 
    png_debug(1, "in png_handle_gAMA");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before gAMA");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid gAMA after IDAT");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (png_ptr->mode & PNG_HAVE_PLTE)
       /* Should be an error, but we can cope with it */
       png_warning(png_ptr, "Out of place gAMA chunk");
 
    if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA)
 #ifdef PNG_READ_sRGB_SUPPORTED
-      && !(info_ptr->valid & PNG_INFO_sRGB)
+       && !(info_ptr->valid & PNG_INFO_sRGB)
 #endif
-      )
+       )
    {
       png_warning(png_ptr, "Duplicate gAMA chunk");
       png_crc_finish(png_ptr, length);
@@ -722,41 +826,43 @@ png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    png_crc_read(png_ptr, buf, 4);
+
    if (png_crc_finish(png_ptr, 0))
       return;
 
-   igamma = (png_fixed_point)png_get_uint_32(buf);
-   /* Check for zero gamma */
-   if (igamma == 0)
-      {
-         png_warning(png_ptr,
-           "Ignoring gAMA chunk with gamma=0");
-         return;
-      }
+   igamma = png_get_fixed_point(NULL, buf);
 
-#ifdef PNG_READ_sRGB_SUPPORTED
+   /* Check for zero gamma or an error. */
+   if (igamma <= 0)
+   {
+      png_warning(png_ptr,
+          "Ignoring gAMA chunk with out of range gamma");
+
+      return;
+   }
+
+#  ifdef PNG_READ_sRGB_SUPPORTED
    if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))
+   {
       if (PNG_OUT_OF_RANGE(igamma, 45500L, 500))
       {
          png_warning(png_ptr,
-           "Ignoring incorrect gAMA value when sRGB is also present");
-#ifdef PNG_CONSOLE_IO_SUPPORTED
+             "Ignoring incorrect gAMA value when sRGB is also present");
+
+#    ifdef PNG_CONSOLE_IO_SUPPORTED
          fprintf(stderr, "gamma = (%d/100000)", (int)igamma);
-#endif
+#    endif
          return;
       }
-#endif /* PNG_READ_sRGB_SUPPORTED */
+   }
+#  endif /* PNG_READ_sRGB_SUPPORTED */
 
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   file_gamma = (float)igamma / (float)100000.0;
 #  ifdef PNG_READ_GAMMA_SUPPORTED
-     png_ptr->gamma = file_gamma;
+   /* Gamma correction on read is supported. */
+   png_ptr->gamma = igamma;
 #  endif
-     png_set_gAMA(png_ptr, info_ptr, file_gamma);
-#endif
-#ifdef PNG_FIXED_POINT_SUPPORTED
+   /* And set the 'info' structure members. */
    png_set_gAMA_fixed(png_ptr, info_ptr, igamma);
-#endif
 }
 #endif
 
@@ -773,17 +879,20 @@ png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before sBIT");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid sBIT after IDAT");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (png_ptr->mode & PNG_HAVE_PLTE)
    {
       /* Should be an error, but we can cope with it */
       png_warning(png_ptr, "Out of place sBIT chunk");
    }
+
    if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT))
    {
       png_warning(png_ptr, "Duplicate sBIT chunk");
@@ -793,6 +902,7 @@ png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       truelen = 3;
+
    else
       truelen = (png_size_t)png_ptr->channels;
 
@@ -804,6 +914,7 @@ png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    png_crc_read(png_ptr, buf, truelen);
+
    if (png_crc_finish(png_ptr, 0))
       return;
 
@@ -814,6 +925,7 @@ png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       png_ptr->sig_bit.blue = buf[2];
       png_ptr->sig_bit.alpha = buf[3];
    }
+
    else
    {
       png_ptr->sig_bit.gray = buf[0];
@@ -822,6 +934,7 @@ png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       png_ptr->sig_bit.blue = buf[0];
       png_ptr->sig_bit.alpha = buf[1];
    }
+
    png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
 }
 #endif
@@ -831,32 +944,29 @@ void /* PRIVATE */
 png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_byte buf[32];
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   float white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y;
-#endif
-   png_fixed_point int_x_white, int_y_white, int_x_red, int_y_red, int_x_green,
-      int_y_green, int_x_blue, int_y_blue;
-
-   png_uint_32 uint_x, uint_y;
+   png_fixed_point x_white, y_white, x_red, y_red, x_green, y_green, x_blue,
+      y_blue;
 
    png_debug(1, "in png_handle_cHRM");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before cHRM");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid cHRM after IDAT");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (png_ptr->mode & PNG_HAVE_PLTE)
       /* Should be an error, but we can cope with it */
       png_warning(png_ptr, "Missing PLTE before cHRM");
 
    if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM)
-#ifdef PNG_READ_sRGB_SUPPORTED
-      && !(info_ptr->valid & PNG_INFO_sRGB)
-#endif
+#  ifdef PNG_READ_sRGB_SUPPORTED
+       && !(info_ptr->valid & PNG_INFO_sRGB)
+#  endif
       )
    {
       png_warning(png_ptr, "Duplicate cHRM chunk");
@@ -872,81 +982,61 @@ png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    png_crc_read(png_ptr, buf, 32);
+
    if (png_crc_finish(png_ptr, 0))
       return;
 
-   uint_x = png_get_uint_32(buf);
-   uint_y = png_get_uint_32(buf + 4);
-   int_x_white = (png_fixed_point)uint_x;
-   int_y_white = (png_fixed_point)uint_y;
+   x_white = png_get_fixed_point(NULL, buf);
+   y_white = png_get_fixed_point(NULL, buf + 4);
+   x_red   = png_get_fixed_point(NULL, buf + 8);
+   y_red   = png_get_fixed_point(NULL, buf + 12);
+   x_green = png_get_fixed_point(NULL, buf + 16);
+   y_green = png_get_fixed_point(NULL, buf + 20);
+   x_blue  = png_get_fixed_point(NULL, buf + 24);
+   y_blue  = png_get_fixed_point(NULL, buf + 28);
 
-   uint_x = png_get_uint_32(buf + 8);
-   uint_y = png_get_uint_32(buf + 12);
-   int_x_red = (png_fixed_point)uint_x;
-   int_y_red = (png_fixed_point)uint_y;
-
-   uint_x = png_get_uint_32(buf + 16);
-   uint_y = png_get_uint_32(buf + 20);
-   int_x_green = (png_fixed_point)uint_x;
-   int_y_green = (png_fixed_point)uint_y;
-
-   uint_x = png_get_uint_32(buf + 24);
-   uint_y = png_get_uint_32(buf + 28);
-   int_x_blue = (png_fixed_point)uint_x;
-   int_y_blue = (png_fixed_point)uint_y;
-
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   white_x = (float)int_x_white / (float)100000.0;
-   white_y = (float)int_y_white / (float)100000.0;
-   red_x   = (float)int_x_red   / (float)100000.0;
-   red_y   = (float)int_y_red   / (float)100000.0;
-   green_x = (float)int_x_green / (float)100000.0;
-   green_y = (float)int_y_green / (float)100000.0;
-   blue_x  = (float)int_x_blue  / (float)100000.0;
-   blue_y  = (float)int_y_blue  / (float)100000.0;
-#endif
+   if (x_white == PNG_FIXED_ERROR ||
+       y_white == PNG_FIXED_ERROR ||
+       x_red   == PNG_FIXED_ERROR ||
+       y_red   == PNG_FIXED_ERROR ||
+       x_green == PNG_FIXED_ERROR ||
+       y_green == PNG_FIXED_ERROR ||
+       x_blue  == PNG_FIXED_ERROR ||
+       y_blue  == PNG_FIXED_ERROR)
+   {
+      png_warning(png_ptr, "Ignoring cHRM chunk with negative chromaticities");
+      return;
+   }
 
 #ifdef PNG_READ_sRGB_SUPPORTED
    if ((info_ptr != NULL) && (info_ptr->valid & PNG_INFO_sRGB))
+   {
+      if (PNG_OUT_OF_RANGE(x_white, 31270,  1000) ||
+          PNG_OUT_OF_RANGE(y_white, 32900,  1000) ||
+          PNG_OUT_OF_RANGE(x_red,   64000L, 1000) ||
+          PNG_OUT_OF_RANGE(y_red,   33000,  1000) ||
+          PNG_OUT_OF_RANGE(x_green, 30000,  1000) ||
+          PNG_OUT_OF_RANGE(y_green, 60000L, 1000) ||
+          PNG_OUT_OF_RANGE(x_blue,  15000,  1000) ||
+          PNG_OUT_OF_RANGE(y_blue,   6000,  1000))
       {
-      if (PNG_OUT_OF_RANGE(int_x_white, 31270,  1000) ||
-          PNG_OUT_OF_RANGE(int_y_white, 32900,  1000) ||
-          PNG_OUT_OF_RANGE(int_x_red,   64000L, 1000) ||
-          PNG_OUT_OF_RANGE(int_y_red,   33000,  1000) ||
-          PNG_OUT_OF_RANGE(int_x_green, 30000,  1000) ||
-          PNG_OUT_OF_RANGE(int_y_green, 60000L, 1000) ||
-          PNG_OUT_OF_RANGE(int_x_blue,  15000,  1000) ||
-          PNG_OUT_OF_RANGE(int_y_blue,   6000,  1000))
-         {
-            png_warning(png_ptr,
-              "Ignoring incorrect cHRM value when sRGB is also present");
+         png_warning(png_ptr,
+             "Ignoring incorrect cHRM value when sRGB is also present");
+
 #ifdef PNG_CONSOLE_IO_SUPPORTED
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-            fprintf(stderr, "wx=%f, wy=%f, rx=%f, ry=%f\n",
-               white_x, white_y, red_x, red_y);
-            fprintf(stderr, "gx=%f, gy=%f, bx=%f, by=%f\n",
-               green_x, green_y, blue_x, blue_y);
-#else
-            fprintf(stderr, "wx=%ld, wy=%ld, rx=%ld, ry=%ld\n",
-               int_x_white, int_y_white, int_x_red, int_y_red);
-            fprintf(stderr, "gx=%ld, gy=%ld, bx=%ld, by=%ld\n",
-               int_x_green, int_y_green, int_x_blue, int_y_blue);
-#endif
+         fprintf(stderr, "wx=%d, wy=%d, rx=%d, ry=%d\n",
+             x_white, y_white, x_red, y_red);
+
+         fprintf(stderr, "gx=%d, gy=%d, bx=%d, by=%d\n",
+             x_green, y_green, x_blue, y_blue);
 #endif /* PNG_CONSOLE_IO_SUPPORTED */
-         }
-         return;
       }
+      return;
+   }
 #endif /* PNG_READ_sRGB_SUPPORTED */
 
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   png_set_cHRM(png_ptr, info_ptr,
-      white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y);
-#endif
-#ifdef PNG_FIXED_POINT_SUPPORTED
-   png_set_cHRM_fixed(png_ptr, info_ptr,
-      int_x_white, int_y_white, int_x_red, int_y_red, int_x_green,
-      int_y_green, int_x_blue, int_y_blue);
-#endif
+   png_set_cHRM_fixed(png_ptr, info_ptr, x_white, y_white, x_red, y_red,
+      x_green, y_green, x_blue, y_blue);
 }
 #endif
 
@@ -961,12 +1051,14 @@ png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before sRGB");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid sRGB after IDAT");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (png_ptr->mode & PNG_HAVE_PLTE)
       /* Should be an error, but we can cope with it */
       png_warning(png_ptr, "Out of place sRGB chunk");
@@ -986,10 +1078,12 @@ png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    png_crc_read(png_ptr, buf, 1);
+
    if (png_crc_finish(png_ptr, 0))
       return;
 
    intent = buf[0];
+
    /* Check for bad intent */
    if (intent >= PNG_sRGB_INTENT_LAST)
    {
@@ -1000,48 +1094,31 @@ png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #if defined(PNG_READ_gAMA_SUPPORTED) && defined(PNG_READ_GAMMA_SUPPORTED)
    if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA))
    {
-   png_fixed_point igamma;
-#ifdef PNG_FIXED_POINT_SUPPORTED
-      igamma=info_ptr->int_gamma;
-#else
-#  ifdef PNG_FLOATING_POINT_SUPPORTED
-      igamma=(png_fixed_point)(info_ptr->gamma * 100000.);
-#  endif
-#endif
-      if (PNG_OUT_OF_RANGE(igamma, 45500L, 500))
+      if (PNG_OUT_OF_RANGE(info_ptr->gamma, 45500L, 500))
       {
          png_warning(png_ptr,
-           "Ignoring incorrect gAMA value when sRGB is also present");
+             "Ignoring incorrect gAMA value when sRGB is also present");
 #ifdef PNG_CONSOLE_IO_SUPPORTED
-#  ifdef PNG_FIXED_POINT_SUPPORTED
-         fprintf(stderr, "incorrect gamma=(%d/100000)\n",
-            (int)png_ptr->int_gamma);
-#  else
-#    ifdef PNG_FLOATING_POINT_SUPPORTED
-         fprintf(stderr, "incorrect gamma=%f\n", png_ptr->gamma);
-#    endif
-#  endif
+         fprintf(stderr, "incorrect gamma=(%d/100000)\n", info_ptr->gamma);
 #endif
       }
    }
 #endif /* PNG_READ_gAMA_SUPPORTED */
 
 #ifdef PNG_READ_cHRM_SUPPORTED
-#ifdef PNG_FIXED_POINT_SUPPORTED
    if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM))
-      if (PNG_OUT_OF_RANGE(info_ptr->int_x_white, 31270,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->int_y_white, 32900,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->int_x_red,   64000L, 1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->int_y_red,   33000,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->int_x_green, 30000,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->int_y_green, 60000L, 1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->int_x_blue,  15000,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->int_y_blue,   6000,  1000))
-         {
-            png_warning(png_ptr,
-              "Ignoring incorrect cHRM value when sRGB is also present");
-         }
-#endif /* PNG_FIXED_POINT_SUPPORTED */
+      if (PNG_OUT_OF_RANGE(info_ptr->x_white, 31270,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->y_white, 32900,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->x_red,   64000L, 1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->y_red,   33000,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->x_green, 30000,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->y_green, 60000L, 1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->x_blue,  15000,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->y_blue,   6000,  1000))
+      {
+         png_warning(png_ptr,
+             "Ignoring incorrect cHRM value when sRGB is also present");
+      }
 #endif /* PNG_READ_cHRM_SUPPORTED */
 
    png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr, intent);
@@ -1057,19 +1134,22 @@ png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_bytep pC;
    png_charp profile;
    png_uint_32 skip = 0;
-   png_uint_32 profile_size, profile_length;
+   png_uint_32 profile_size;
+   png_alloc_size_t profile_length;
    png_size_t slength, prefix_length, data_length;
 
    png_debug(1, "in png_handle_iCCP");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before iCCP");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid iCCP after IDAT");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (png_ptr->mode & PNG_HAVE_PLTE)
       /* Should be an error, but we can cope with it */
       png_warning(png_ptr, "Out of place iCCP chunk");
@@ -1112,7 +1192,7 @@ png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    /* There should be at least one zero (the compression type byte)
     * following the separator, and we should be on it
     */
-   if ( profile >= png_ptr->chunkdata + slength - 1)
+   if (profile >= png_ptr->chunkdata + slength - 1)
    {
       png_free(png_ptr, png_ptr->chunkdata);
       png_ptr->chunkdata = NULL;
@@ -1122,6 +1202,7 @@ png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    /* Compression_type should always be zero */
    compression_type = *profile++;
+
    if (compression_type)
    {
       png_warning(png_ptr, "Ignoring nonzero compression type in iCCP chunk");
@@ -1131,11 +1212,11 @@ png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    prefix_length = profile - png_ptr->chunkdata;
    png_decompress_chunk(png_ptr, compression_type,
-     slength, prefix_length, &data_length);
+       slength, prefix_length, &data_length);
 
    profile_length = data_length - prefix_length;
 
-   if ( prefix_length > data_length || profile_length < 4)
+   if (prefix_length > data_length || profile_length < 4)
    {
       png_free(png_ptr, png_ptr->chunkdata);
       png_ptr->chunkdata = NULL;
@@ -1145,24 +1226,43 @@ png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    /* Check the profile_size recorded in the first 32 bits of the ICC profile */
    pC = (png_bytep)(png_ptr->chunkdata + prefix_length);
-   profile_size = ((*(pC    ))<<24) |
-                  ((*(pC + 1))<<16) |
-                  ((*(pC + 2))<< 8) |
-                  ((*(pC + 3))    );
+   profile_size = ((*(pC    )) << 24) |
+                  ((*(pC + 1)) << 16) |
+                  ((*(pC + 2)) <<  8) |
+                  ((*(pC + 3))      );
 
+   /* NOTE: the following guarantees that 'profile_length' fits into 32 bits,
+    * because profile_size is a 32 bit value.
+    */
    if (profile_size < profile_length)
       profile_length = profile_size;
 
+   /* And the following guarantees that profile_size == profile_length. */
    if (profile_size > profile_length)
    {
       png_free(png_ptr, png_ptr->chunkdata);
       png_ptr->chunkdata = NULL;
-      png_warning(png_ptr, "Ignoring truncated iCCP profile");
+#ifdef PNG_STDIO_SUPPORTED
+      {
+         char umsg[80];
+
+         png_snprintf2(umsg, 80,
+             "Ignoring iCCP chunk with declared size = %u "
+              "and actual length = %u",
+              (unsigned int) profile_size,
+              (unsigned int) profile_length);
+         png_warning(png_ptr, umsg);
+      }
+#else
+      png_warning(png_ptr,
+         "Ignoring iCCP chunk with uncompressed size mismatch");
+#endif
       return;
    }
 
    png_set_iCCP(png_ptr, info_ptr, png_ptr->chunkdata,
-     compression_type, png_ptr->chunkdata + prefix_length, profile_length);
+       compression_type, (png_bytep)png_ptr->chunkdata + prefix_length,
+       profile_size);
    png_free(png_ptr, png_ptr->chunkdata);
    png_ptr->chunkdata = NULL;
 }
@@ -1178,9 +1278,12 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #ifdef PNG_POINTER_INDEXING_SUPPORTED
    png_sPLT_entryp pp;
 #endif
-   int data_length, entry_size, i;
+   png_uint_32 data_length;
+   int entry_size, i;
    png_uint_32 skip = 0;
    png_size_t slength;
+   png_uint_32 dl;
+   png_size_t max_dl;
 
    png_debug(1, "in png_handle_sPLT");
 
@@ -1193,6 +1296,7 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
          png_crc_finish(png_ptr, length);
          return;
       }
+
       if (--png_ptr->user_chunk_cache_max == 1)
       {
          png_warning(png_ptr, "No space in chunk cache for sPLT");
@@ -1204,6 +1308,7 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before sPLT");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid sPLT after IDAT");
@@ -1222,6 +1327,11 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    png_free(png_ptr, png_ptr->chunkdata);
    png_ptr->chunkdata = (png_charp)png_malloc(png_ptr, length + 1);
+
+   /* WARNING: this may break if size_t is less than 32 bits; it is assumed
+    * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
+    * potential breakage point if the types in pngconf.h aren't exactly right.
+    */
    slength = (png_size_t)length;
    png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
@@ -1237,6 +1347,7 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    for (entry_start = (png_bytep)png_ptr->chunkdata; *entry_start;
        entry_start++)
       /* Empty loop to find end of name */ ;
+
    ++entry_start;
 
    /* A sample depth should follow the separator, and we should be on it  */
@@ -1250,7 +1361,12 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    new_palette.depth = *entry_start++;
    entry_size = (new_palette.depth == 8 ? 6 : 10);
-   data_length = (slength - (entry_start - (png_bytep)png_ptr->chunkdata));
+   /* This must fit in a png_uint_32 because it is derived from the original
+    * chunk data length (and use 'length', not 'slength' here for clarity -
+    * they are guaranteed to be the same, see the tests above.)
+    */
+   data_length = length - (png_uint_32)(entry_start -
+      (png_bytep)png_ptr->chunkdata);
 
    /* Integrity-check the data length */
    if (data_length % entry_size)
@@ -1261,15 +1377,20 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
 
-   new_palette.nentries = (png_int_32) ( data_length / entry_size);
-   if ((png_uint_32) new_palette.nentries >
-       (png_uint_32) (PNG_SIZE_MAX / png_sizeof(png_sPLT_entry)))
+   dl = (png_int_32)(data_length / entry_size);
+   max_dl = PNG_SIZE_MAX / png_sizeof(png_sPLT_entry);
+
+   if (dl > max_dl)
    {
        png_warning(png_ptr, "sPLT chunk too long");
        return;
    }
+
+   new_palette.nentries = (png_int_32)(data_length / entry_size);
+
    new_palette.entries = (png_sPLT_entryp)png_malloc_warn(
        png_ptr, new_palette.nentries * png_sizeof(png_sPLT_entry));
+
    if (new_palette.entries == NULL)
    {
        png_warning(png_ptr, "sPLT chunk requires too much memory");
@@ -1283,39 +1404,44 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
       if (new_palette.depth == 8)
       {
-          pp->red = *entry_start++;
-          pp->green = *entry_start++;
-          pp->blue = *entry_start++;
-          pp->alpha = *entry_start++;
+         pp->red = *entry_start++;
+         pp->green = *entry_start++;
+         pp->blue = *entry_start++;
+         pp->alpha = *entry_start++;
       }
+
       else
       {
-          pp->red   = png_get_uint_16(entry_start); entry_start += 2;
-          pp->green = png_get_uint_16(entry_start); entry_start += 2;
-          pp->blue  = png_get_uint_16(entry_start); entry_start += 2;
-          pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
+         pp->red   = png_get_uint_16(entry_start); entry_start += 2;
+         pp->green = png_get_uint_16(entry_start); entry_start += 2;
+         pp->blue  = png_get_uint_16(entry_start); entry_start += 2;
+         pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
       }
+
       pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
    }
 #else
    pp = new_palette.entries;
+
    for (i = 0; i < new_palette.nentries; i++)
    {
 
       if (new_palette.depth == 8)
       {
-          pp[i].red   = *entry_start++;
-          pp[i].green = *entry_start++;
-          pp[i].blue  = *entry_start++;
-          pp[i].alpha = *entry_start++;
+         pp[i].red   = *entry_start++;
+         pp[i].green = *entry_start++;
+         pp[i].blue  = *entry_start++;
+         pp[i].alpha = *entry_start++;
       }
+
       else
       {
-          pp[i].red   = png_get_uint_16(entry_start); entry_start += 2;
-          pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
-          pp[i].blue  = png_get_uint_16(entry_start); entry_start += 2;
-          pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
+         pp[i].red   = png_get_uint_16(entry_start); entry_start += 2;
+         pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
+         pp[i].blue  = png_get_uint_16(entry_start); entry_start += 2;
+         pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
       }
+
       pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
    }
 #endif
@@ -1341,12 +1467,14 @@ png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before tRNS");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid tRNS after IDAT");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
    {
       png_warning(png_ptr, "Duplicate tRNS chunk");
@@ -1369,6 +1497,7 @@ png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       png_ptr->num_trans = 1;
       png_ptr->trans_color.gray = png_get_uint_16(buf);
    }
+
    else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
    {
       png_byte buf[6];
@@ -1379,12 +1508,14 @@ png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
          png_crc_finish(png_ptr, length);
          return;
       }
+
       png_crc_read(png_ptr, buf, (png_size_t)length);
       png_ptr->num_trans = 1;
       png_ptr->trans_color.red = png_get_uint_16(buf);
       png_ptr->trans_color.green = png_get_uint_16(buf + 2);
       png_ptr->trans_color.blue = png_get_uint_16(buf + 4);
    }
+
    else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
    {
       if (!(png_ptr->mode & PNG_HAVE_PLTE))
@@ -1392,6 +1523,7 @@ png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
          /* Should be an error, but we can cope with it. */
          png_warning(png_ptr, "Missing PLTE before tRNS");
       }
+
       if (length > (png_uint_32)png_ptr->num_palette ||
           length > PNG_MAX_PALETTE_LENGTH)
       {
@@ -1399,15 +1531,18 @@ png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
          png_crc_finish(png_ptr, length);
          return;
       }
+
       if (length == 0)
       {
          png_warning(png_ptr, "Zero length tRNS chunk");
          png_crc_finish(png_ptr, length);
          return;
       }
+
       png_crc_read(png_ptr, readbuf, (png_size_t)length);
       png_ptr->num_trans = (png_uint_16)length;
    }
+
    else
    {
       png_warning(png_ptr, "tRNS chunk not allowed with alpha channel");
@@ -1422,7 +1557,7 @@ png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
-      &(png_ptr->trans_color));
+       &(png_ptr->trans_color));
 }
 #endif
 
@@ -1437,19 +1572,22 @@ png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before bKGD");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid bKGD after IDAT");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
-            !(png_ptr->mode & PNG_HAVE_PLTE))
+       !(png_ptr->mode & PNG_HAVE_PLTE))
    {
       png_warning(png_ptr, "Missing PLTE before bKGD");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD))
    {
       png_warning(png_ptr, "Duplicate bKGD chunk");
@@ -1459,8 +1597,10 @@ png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       truelen = 1;
+
    else if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
       truelen = 6;
+
    else
       truelen = 2;
 
@@ -1472,31 +1612,38 @@ png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    png_crc_read(png_ptr, buf, truelen);
+
    if (png_crc_finish(png_ptr, 0))
       return;
 
    /* We convert the index value into RGB components so that we can allow
     * arbitrary RGB values for background when we have transparency, and
     * so it is easy to determine the RGB values of the background color
-    * from the info_ptr struct. */
+    * from the info_ptr struct.
+    */
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
    {
       png_ptr->background.index = buf[0];
+
       if (info_ptr && info_ptr->num_palette)
       {
-          if (buf[0] >= info_ptr->num_palette)
-          {
-             png_warning(png_ptr, "Incorrect bKGD chunk index value");
-             return;
-          }
-          png_ptr->background.red =
+         if (buf[0] >= info_ptr->num_palette)
+         {
+            png_warning(png_ptr, "Incorrect bKGD chunk index value");
+            return;
+         }
+
+         png_ptr->background.red =
              (png_uint_16)png_ptr->palette[buf[0]].red;
-          png_ptr->background.green =
+
+         png_ptr->background.green =
              (png_uint_16)png_ptr->palette[buf[0]].green;
-          png_ptr->background.blue =
+
+         png_ptr->background.blue =
              (png_uint_16)png_ptr->palette[buf[0]].blue;
       }
    }
+
    else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */
    {
       png_ptr->background.red =
@@ -1504,6 +1651,7 @@ png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       png_ptr->background.blue =
       png_ptr->background.gray = png_get_uint_16(buf);
    }
+
    else
    {
       png_ptr->background.red = png_get_uint_16(buf);
@@ -1526,18 +1674,21 @@ png_handle_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before hIST");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid hIST after IDAT");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (!(png_ptr->mode & PNG_HAVE_PLTE))
    {
       png_warning(png_ptr, "Missing PLTE before hIST");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST))
    {
       png_warning(png_ptr, "Duplicate hIST chunk");
@@ -1546,8 +1697,9 @@ png_handle_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    num = length / 2 ;
-   if (num != (unsigned int) png_ptr->num_palette || num >
-      (unsigned int) PNG_MAX_PALETTE_LENGTH)
+
+   if (num != (unsigned int)png_ptr->num_palette || num >
+       (unsigned int)PNG_MAX_PALETTE_LENGTH)
    {
       png_warning(png_ptr, "Incorrect hIST chunk length");
       png_crc_finish(png_ptr, length);
@@ -1581,12 +1733,14 @@ png_handle_pHYs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before pHYs");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid pHYs after IDAT");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
    {
       png_warning(png_ptr, "Duplicate pHYs chunk");
@@ -1602,6 +1756,7 @@ png_handle_pHYs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    png_crc_read(png_ptr, buf, 9);
+
    if (png_crc_finish(png_ptr, 0))
       return;
 
@@ -1624,12 +1779,14 @@ png_handle_oFFs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before oFFs");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid oFFs after IDAT");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
    {
       png_warning(png_ptr, "Duplicate oFFs chunk");
@@ -1645,6 +1802,7 @@ png_handle_oFFs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    png_crc_read(png_ptr, buf, 9);
+
    if (png_crc_finish(png_ptr, 0))
       return;
 
@@ -1671,12 +1829,14 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before pCAL");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid pCAL after IDAT");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL))
    {
       png_warning(png_ptr, "Duplicate pCAL chunk");
@@ -1684,15 +1844,17 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
 
-   png_debug1(2, "Allocating and reading pCAL chunk data (%lu bytes)",
-      length + 1);
+   png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
+       length + 1);
    png_free(png_ptr, png_ptr->chunkdata);
    png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+
    if (png_ptr->chunkdata == NULL)
-     {
-       png_warning(png_ptr, "No memory for pCAL purpose");
-       return;
-     }
+   {
+      png_warning(png_ptr, "No memory for pCAL purpose");
+      return;
+   }
+
    slength = (png_size_t)length;
    png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
@@ -1712,7 +1874,8 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    endptr = png_ptr->chunkdata + slength;
 
    /* We need to have at least 12 bytes after the purpose string
-      in order to get the parameter information. */
+    * in order to get the parameter information.
+    */
    if (endptr <= buf + 12)
    {
       png_warning(png_ptr, "Invalid pCAL data");
@@ -1730,7 +1893,8 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    png_debug(3, "Checking pCAL equation type and number of parameters");
    /* Check that we have the right number of parameters for known
-      equation types. */
+    * equation types.
+    */
    if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
        (type == PNG_EQUATION_BASE_E && nparams != 3) ||
        (type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
@@ -1741,6 +1905,7 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       png_ptr->chunkdata = NULL;
       return;
    }
+
    else if (type >= PNG_EQUATION_LAST)
    {
       png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
@@ -1750,15 +1915,17 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       /* Empty loop to move past the units string. */ ;
 
    png_debug(3, "Allocating pCAL parameters array");
+
    params = (png_charpp)png_malloc_warn(png_ptr,
-      (png_size_t)(nparams * png_sizeof(png_charp)));
+       (png_size_t)(nparams * png_sizeof(png_charp)));
+
    if (params == NULL)
-     {
-       png_free(png_ptr, png_ptr->chunkdata);
-       png_ptr->chunkdata = NULL;
-       png_warning(png_ptr, "No memory for pCAL params");
-       return;
-     }
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      png_warning(png_ptr, "No memory for pCAL params");
+      return;
+   }
 
    /* Get pointers to the start of each parameter string. */
    for (i = 0; i < (int)nparams; i++)
@@ -1766,6 +1933,7 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       buf++; /* Skip the null string terminator from previous parameter. */
 
       png_debug1(3, "Reading pCAL parameter %d", i);
+
       for (params[i] = buf; buf <= endptr && *buf != 0x00; buf++)
          /* Empty loop to move past each parameter string */ ;
 
@@ -1794,27 +1962,21 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 void /* PRIVATE */
 png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
-   png_charp ep;
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   double width, height;
-   png_charp vp;
-#else
-#ifdef PNG_FIXED_POINT_SUPPORTED
-   png_charp swidth, sheight;
-#endif
-#endif
-   png_size_t slength;
+   png_size_t slength, index;
+   int state;
 
    png_debug(1, "in png_handle_sCAL");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before sCAL");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid sCAL after IDAT");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL))
    {
       png_warning(png_ptr, "Duplicate sCAL chunk");
@@ -1822,16 +1984,21 @@ png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
 
-   png_debug1(2, "Allocating and reading sCAL chunk data (%lu bytes)",
+   png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
       length + 1);
+
    png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+
    if (png_ptr->chunkdata == NULL)
    {
       png_warning(png_ptr, "Out of memory while processing sCAL chunk");
+      png_crc_finish(png_ptr, length);
       return;
    }
+
    slength = (png_size_t)length;
    png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
 
    if (png_crc_finish(png_ptr, 0))
    {
@@ -1840,95 +2007,44 @@ png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
 
-   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
-
-   ep = png_ptr->chunkdata + 1;        /* Skip unit byte */
-
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   width = png_strtod(png_ptr, ep, &vp);
-   if (*vp)
+   /* Validate the unit. */
+   if (png_ptr->chunkdata[0] != 1 && png_ptr->chunkdata[0] != 2)
    {
-      png_warning(png_ptr, "malformed width string in sCAL chunk");
-      return;
-   }
-#else
-#ifdef PNG_FIXED_POINT_SUPPORTED
-   swidth = (png_charp)png_malloc_warn(png_ptr, png_strlen(ep) + 1);
-   if (swidth == NULL)
-   {
-      png_warning(png_ptr, "Out of memory while processing sCAL chunk width");
-      return;
-   }
-   png_memcpy(swidth, ep, png_strlen(ep));
-#endif
-#endif
-
-   for (ep = png_ptr->chunkdata; *ep; ep++)
-      /* Empty loop */ ;
-   ep++;
-
-   if (png_ptr->chunkdata + slength < ep)
-   {
-      png_warning(png_ptr, "Truncated sCAL chunk");
-#if defined(PNG_FIXED_POINT_SUPPORTED) && \
-    !defined(PNG_FLOATING_POINT_SUPPORTED)
-      png_free(png_ptr, swidth);
-#endif
+      png_warning(png_ptr, "Invalid sCAL ignored: invalid unit");
       png_free(png_ptr, png_ptr->chunkdata);
       png_ptr->chunkdata = NULL;
       return;
    }
 
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   height = png_strtod(png_ptr, ep, &vp);
-   if (*vp)
-   {
-      png_warning(png_ptr, "malformed height string in sCAL chunk");
-      return;
-   }
-#else
-#ifdef PNG_FIXED_POINT_SUPPORTED
-   sheight = (png_charp)png_malloc_warn(png_ptr, png_strlen(ep) + 1);
-   if (sheight == NULL)
-   {
-      png_warning(png_ptr, "Out of memory while processing sCAL chunk height");
-      return;
-   }
-   png_memcpy(sheight, ep, png_strlen(ep));
-#endif
-#endif
+   /* Validate the ASCII numbers, need two ASCII numbers separated by
+    * a '\0' and they need to fit exactly in the chunk data.
+    */
+   index = 0;
+   state = 0;
 
-   if (png_ptr->chunkdata + slength < ep
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-      || width <= 0. || height <= 0.
-#endif
-      )
+   if (png_ptr->chunkdata[1] == 45 /* negative width */ ||
+       !png_check_fp_number(png_ptr->chunkdata, slength, &state, &index) ||
+       index >= slength || png_ptr->chunkdata[index++] != 0)
+      png_warning(png_ptr, "Invalid sCAL chunk ignored: bad width format");
+
+   else
    {
-      png_warning(png_ptr, "Invalid sCAL data");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-#if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
-      png_free(png_ptr, swidth);
-      png_free(png_ptr, sheight);
-#endif
-      return;
+      png_size_t heighti = index;
+
+      if (png_ptr->chunkdata[index] == 45 /* negative height */ ||
+          !png_check_fp_number(png_ptr->chunkdata, slength, &state, &index) ||
+          index != slength)
+         png_warning(png_ptr, "Invalid sCAL chunk ignored: bad height format");
+
+      else
+         /* This is the (only) success case. */
+         png_set_sCAL_s(png_ptr, info_ptr, png_ptr->chunkdata[0],
+            png_ptr->chunkdata+1, png_ptr->chunkdata+heighti);
    }
 
-
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   png_set_sCAL(png_ptr, info_ptr, png_ptr->chunkdata[0], width, height);
-#else
-#ifdef PNG_FIXED_POINT_SUPPORTED
-   png_set_sCAL_s(png_ptr, info_ptr, png_ptr->chunkdata[0], swidth, sheight);
-#endif
-#endif
-
+   /* Clean up - just free the temporarily allocated buffer. */
    png_free(png_ptr, png_ptr->chunkdata);
    png_ptr->chunkdata = NULL;
-#if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
-   png_free(png_ptr, swidth);
-   png_free(png_ptr, sheight);
-#endif
 }
 #endif
 
@@ -1943,6 +2059,7 @@ png_handle_tIME(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Out of place tIME chunk");
+
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME))
    {
       png_warning(png_ptr, "Duplicate tIME chunk");
@@ -1961,6 +2078,7 @@ png_handle_tIME(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    png_crc_read(png_ptr, buf, 7);
+
    if (png_crc_finish(png_ptr, 0))
       return;
 
@@ -1997,6 +2115,7 @@ png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
          png_crc_finish(png_ptr, length);
          return;
       }
+
       if (--png_ptr->user_chunk_cache_max == 1)
       {
          png_warning(png_ptr, "No space in chunk cache for tEXt");
@@ -2024,11 +2143,13 @@ png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_free(png_ptr, png_ptr->chunkdata);
 
    png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+
    if (png_ptr->chunkdata == NULL)
    {
      png_warning(png_ptr, "No memory to process text chunk");
      return;
    }
+
    slength = (png_size_t)length;
    png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
@@ -2050,21 +2171,21 @@ png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       text++;
 
    text_ptr = (png_textp)png_malloc_warn(png_ptr,
-      png_sizeof(png_text));
+       png_sizeof(png_text));
+
    if (text_ptr == NULL)
    {
-     png_warning(png_ptr, "Not enough memory to process text chunk");
-     png_free(png_ptr, png_ptr->chunkdata);
-     png_ptr->chunkdata = NULL;
-     return;
+      png_warning(png_ptr, "Not enough memory to process text chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
    }
+
    text_ptr->compression = PNG_TEXT_COMPRESSION_NONE;
    text_ptr->key = key;
-#ifdef PNG_iTXt_SUPPORTED
    text_ptr->lang = NULL;
    text_ptr->lang_key = NULL;
    text_ptr->itxt_length = 0;
-#endif
    text_ptr->text = text;
    text_ptr->text_length = png_strlen(text);
 
@@ -2073,8 +2194,9 @@ png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_free(png_ptr, png_ptr->chunkdata);
    png_ptr->chunkdata = NULL;
    png_free(png_ptr, text_ptr);
+
    if (ret)
-     png_warning(png_ptr, "Insufficient memory to process text chunk");
+      png_warning(png_ptr, "Insufficient memory to process text chunk");
 }
 #endif
 
@@ -2099,6 +2221,7 @@ png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
          png_crc_finish(png_ptr, length);
          return;
       }
+
       if (--png_ptr->user_chunk_cache_max == 1)
       {
          png_warning(png_ptr, "No space in chunk cache for zTXt");
@@ -2116,24 +2239,28 @@ png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
 #ifdef PNG_MAX_MALLOC_64K
    /* We will no doubt have problems with chunks even half this size, but
-      there is no hard and fast rule to tell us where to stop. */
+    * there is no hard and fast rule to tell us where to stop.
+    */
    if (length > (png_uint_32)65535L)
    {
-     png_warning(png_ptr, "zTXt chunk too large to fit in memory");
-     png_crc_finish(png_ptr, length);
-     return;
+      png_warning(png_ptr, "zTXt chunk too large to fit in memory");
+      png_crc_finish(png_ptr, length);
+      return;
    }
 #endif
 
    png_free(png_ptr, png_ptr->chunkdata);
    png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+
    if (png_ptr->chunkdata == NULL)
    {
-     png_warning(png_ptr, "Out of memory processing zTXt chunk");
-     return;
+      png_warning(png_ptr, "Out of memory processing zTXt chunk");
+      return;
    }
+
    slength = (png_size_t)length;
    png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+
    if (png_crc_finish(png_ptr, 0))
    {
       png_free(png_ptr, png_ptr->chunkdata);
@@ -2154,37 +2281,41 @@ png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       png_ptr->chunkdata = NULL;
       return;
    }
+
    else
    {
        comp_type = *(++text);
+
        if (comp_type != PNG_TEXT_COMPRESSION_zTXt)
        {
           png_warning(png_ptr, "Unknown compression type in zTXt chunk");
           comp_type = PNG_TEXT_COMPRESSION_zTXt;
        }
+
        text++;        /* Skip the compression_method byte */
    }
+
    prefix_len = text - png_ptr->chunkdata;
 
    png_decompress_chunk(png_ptr, comp_type,
-     (png_size_t)length, prefix_len, &data_len);
+       (png_size_t)length, prefix_len, &data_len);
 
    text_ptr = (png_textp)png_malloc_warn(png_ptr,
-      png_sizeof(png_text));
+       png_sizeof(png_text));
+
    if (text_ptr == NULL)
    {
-     png_warning(png_ptr, "Not enough memory to process zTXt chunk");
-     png_free(png_ptr, png_ptr->chunkdata);
-     png_ptr->chunkdata = NULL;
-     return;
+      png_warning(png_ptr, "Not enough memory to process zTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
    }
+
    text_ptr->compression = comp_type;
    text_ptr->key = png_ptr->chunkdata;
-#ifdef PNG_iTXt_SUPPORTED
    text_ptr->lang = NULL;
    text_ptr->lang_key = NULL;
    text_ptr->itxt_length = 0;
-#endif
    text_ptr->text = png_ptr->chunkdata + prefix_len;
    text_ptr->text_length = data_len;
 
@@ -2193,8 +2324,9 @@ png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_free(png_ptr, text_ptr);
    png_free(png_ptr, png_ptr->chunkdata);
    png_ptr->chunkdata = NULL;
+
    if (ret)
-     png_error(png_ptr, "Insufficient memory to store zTXt chunk");
+      png_error(png_ptr, "Insufficient memory to store zTXt chunk");
 }
 #endif
 
@@ -2220,6 +2352,7 @@ png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
          png_crc_finish(png_ptr, length);
          return;
       }
+
       if (--png_ptr->user_chunk_cache_max == 1)
       {
          png_warning(png_ptr, "No space in chunk cache for iTXt");
@@ -2237,24 +2370,28 @@ png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
 #ifdef PNG_MAX_MALLOC_64K
    /* We will no doubt have problems with chunks even half this size, but
-      there is no hard and fast rule to tell us where to stop. */
+    * there is no hard and fast rule to tell us where to stop.
+    */
    if (length > (png_uint_32)65535L)
    {
-     png_warning(png_ptr, "iTXt chunk too large to fit in memory");
-     png_crc_finish(png_ptr, length);
-     return;
+      png_warning(png_ptr, "iTXt chunk too large to fit in memory");
+      png_crc_finish(png_ptr, length);
+      return;
    }
 #endif
 
    png_free(png_ptr, png_ptr->chunkdata);
    png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+
    if (png_ptr->chunkdata == NULL)
    {
-     png_warning(png_ptr, "No memory to process iTXt chunk");
-     return;
+      png_warning(png_ptr, "No memory to process iTXt chunk");
+      return;
    }
+
    slength = (png_size_t)length;
    png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+
    if (png_crc_finish(png_ptr, 0))
    {
       png_free(png_ptr, png_ptr->chunkdata);
@@ -2266,6 +2403,7 @@ png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    for (lang = png_ptr->chunkdata; *lang; lang++)
       /* Empty loop */ ;
+
    lang++;        /* Skip NUL separator */
 
    /* iTXt must have a language tag (possibly empty), two compression bytes,
@@ -2280,14 +2418,16 @@ png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       png_ptr->chunkdata = NULL;
       return;
    }
+
    else
    {
-       comp_flag = *lang++;
-       comp_type = *lang++;
+      comp_flag = *lang++;
+      comp_type = *lang++;
    }
 
    for (lang_key = lang; *lang_key; lang_key++)
       /* Empty loop */ ;
+
    lang_key++;        /* Skip NUL separator */
 
    if (lang_key >= png_ptr->chunkdata + slength)
@@ -2300,7 +2440,9 @@ png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    for (text = lang_key; *text; text++)
       /* Empty loop */ ;
+
    text++;        /* Skip NUL separator */
+
    if (text >= png_ptr->chunkdata + slength)
    {
       png_warning(png_ptr, "Malformed iTXt chunk");
@@ -2312,20 +2454,25 @@ png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    prefix_len = text - png_ptr->chunkdata;
 
    key=png_ptr->chunkdata;
+
    if (comp_flag)
-       png_decompress_chunk(png_ptr, comp_type,
-         (size_t)length, prefix_len, &data_len);
+      png_decompress_chunk(png_ptr, comp_type,
+          (size_t)length, prefix_len, &data_len);
+
    else
-       data_len = png_strlen(png_ptr->chunkdata + prefix_len);
+      data_len = png_strlen(png_ptr->chunkdata + prefix_len);
+
    text_ptr = (png_textp)png_malloc_warn(png_ptr,
-      png_sizeof(png_text));
+       png_sizeof(png_text));
+
    if (text_ptr == NULL)
    {
-     png_warning(png_ptr, "Not enough memory to process iTXt chunk");
-     png_free(png_ptr, png_ptr->chunkdata);
-     png_ptr->chunkdata = NULL;
-     return;
+      png_warning(png_ptr, "Not enough memory to process iTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
    }
+
    text_ptr->compression = (int)comp_flag + 1;
    text_ptr->lang_key = png_ptr->chunkdata + (lang_key - key);
    text_ptr->lang = png_ptr->chunkdata + (lang - key);
@@ -2339,16 +2486,18 @@ png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_free(png_ptr, text_ptr);
    png_free(png_ptr, png_ptr->chunkdata);
    png_ptr->chunkdata = NULL;
+
    if (ret)
-     png_error(png_ptr, "Insufficient memory to store iTXt chunk");
+      png_error(png_ptr, "Insufficient memory to store iTXt chunk");
 }
 #endif
 
 /* This function is called when we haven't found a handler for a
-   chunk.  If there isn't a problem with the chunk itself (ie bad
-   chunk name, CRC, or a critical chunk), the chunk is silently ignored
-   -- unless the PNG_FLAG_UNKNOWN_CHUNKS_SUPPORTED flag is on in which
-   case it will be saved away to be written out later. */
+ * chunk.  If there isn't a problem with the chunk itself (ie bad
+ * chunk name, CRC, or a critical chunk), the chunk is silently ignored
+ * -- unless the PNG_FLAG_UNKNOWN_CHUNKS_SUPPORTED flag is on in which
+ * case it will be saved away to be written out later.
+ */
 void /* PRIVATE */
 png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
@@ -2364,6 +2513,7 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
          png_crc_finish(png_ptr, length);
          return;
       }
+
       if (--png_ptr->user_chunk_cache_max == 1)
       {
          png_warning(png_ptr, "No space in chunk cache for unknown chunk");
@@ -2376,6 +2526,7 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       PNG_IDAT;
+
       if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))  /* Not an IDAT */
          png_ptr->mode |= PNG_AFTER_IDAT;
    }
@@ -2384,13 +2535,13 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    {
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
       if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
-           PNG_HANDLE_CHUNK_ALWAYS
+          PNG_HANDLE_CHUNK_ALWAYS
 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
-           && png_ptr->read_user_chunk_fn == NULL
+          && png_ptr->read_user_chunk_fn == NULL
 #endif
-        )
+          )
 #endif
-          png_chunk_error(png_ptr, "unknown critical chunk");
+         png_chunk_error(png_ptr, "unknown critical chunk");
    }
 
 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
@@ -2398,56 +2549,71 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
        || (png_ptr->read_user_chunk_fn != NULL)
 #endif
-        )
+       )
    {
 #ifdef PNG_MAX_MALLOC_64K
-       if (length > (png_uint_32)65535L)
-       {
-           png_warning(png_ptr, "unknown chunk too large to fit in memory");
-           skip = length - (png_uint_32)65535L;
-           length = (png_uint_32)65535L;
-       }
+      if (length > (png_uint_32)65535L)
+      {
+         png_warning(png_ptr, "unknown chunk too large to fit in memory");
+         skip = length - (png_uint_32)65535L;
+         length = (png_uint_32)65535L;
+      }
 #endif
-       png_memcpy((png_charp)png_ptr->unknown_chunk.name,
-                  (png_charp)png_ptr->chunk_name,
-                  png_sizeof(png_ptr->unknown_chunk.name));
-       png_ptr->unknown_chunk.name[png_sizeof(png_ptr->unknown_chunk.name)-1]
-           = '\0';
-       png_ptr->unknown_chunk.size = (png_size_t)length;
-       if (length == 0)
+
+      png_memcpy((png_charp)png_ptr->unknown_chunk.name,
+          (png_charp)png_ptr->chunk_name,
+          png_sizeof(png_ptr->unknown_chunk.name));
+
+      png_ptr->unknown_chunk.name[png_sizeof(png_ptr->unknown_chunk.name)-1]
+          = '\0';
+
+      png_ptr->unknown_chunk.size = (png_size_t)length;
+
+      if (length == 0)
          png_ptr->unknown_chunk.data = NULL;
-       else
-       {
+
+      else
+      {
          png_ptr->unknown_chunk.data = (png_bytep)png_malloc(png_ptr, length);
          png_crc_read(png_ptr, (png_bytep)png_ptr->unknown_chunk.data, length);
-       }
+      }
+
 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
-       if (png_ptr->read_user_chunk_fn != NULL)
-       {
-          /* Callback to user unknown chunk handler */
-          int ret;
-          ret = (*(png_ptr->read_user_chunk_fn))
-            (png_ptr, &png_ptr->unknown_chunk);
-          if (ret < 0)
-             png_chunk_error(png_ptr, "error in user chunk");
-          if (ret == 0)
-          {
-             if (!(png_ptr->chunk_name[0] & 0x20))
+      if (png_ptr->read_user_chunk_fn != NULL)
+      {
+         /* Callback to user unknown chunk handler */
+         int ret;
+
+         ret = (*(png_ptr->read_user_chunk_fn))
+             (png_ptr, &png_ptr->unknown_chunk);
+
+         if (ret < 0)
+            png_chunk_error(png_ptr, "error in user chunk");
+
+         if (ret == 0)
+         {
+            if (!(png_ptr->chunk_name[0] & 0x20))
+            {
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-                if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
-                     PNG_HANDLE_CHUNK_ALWAYS)
+               if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
+                   PNG_HANDLE_CHUNK_ALWAYS)
 #endif
-                   png_chunk_error(png_ptr, "unknown critical chunk");
-             png_set_unknown_chunks(png_ptr, info_ptr,
-               &png_ptr->unknown_chunk, 1);
-          }
-       }
-       else
+                  png_chunk_error(png_ptr, "unknown critical chunk");
+            }
+
+            png_set_unknown_chunks(png_ptr, info_ptr,
+                &png_ptr->unknown_chunk, 1);
+         }
+      }
+
+      else
 #endif
-       png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1);
-       png_free(png_ptr, png_ptr->unknown_chunk.data);
-       png_ptr->unknown_chunk.data = NULL;
+         png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1);
+
+      png_free(png_ptr, png_ptr->unknown_chunk.data);
+      png_ptr->unknown_chunk.data = NULL;
    }
+
    else
 #endif
       skip = length;
@@ -2455,20 +2621,21 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_crc_finish(png_ptr, skip);
 
 #ifndef PNG_READ_USER_CHUNKS_SUPPORTED
-   info_ptr = info_ptr; /* Quiet compiler warnings about unused info_ptr */
+   PNG_UNUSED(info_ptr) /* Quiet compiler warnings about unused info_ptr */
 #endif
 }
 
 /* This function is called to verify that a chunk name is valid.
-   This function can't have the "critical chunk check" incorporated
-   into it, since in the future we will need to be able to call user
-   functions to handle unknown critical chunks after we check that
-   the chunk name itself is valid. */
+ * This function can't have the "critical chunk check" incorporated
+ * into it, since in the future we will need to be able to call user
+ * functions to handle unknown critical chunks after we check that
+ * the chunk name itself is valid.
+ */
 
 #define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
 
 void /* PRIVATE */
-png_check_chunk_name(png_structp png_ptr, png_bytep chunk_name)
+png_check_chunk_name(png_structp png_ptr, png_const_bytep chunk_name)
 {
    png_debug(1, "in png_check_chunk_name");
    if (isnonalpha(chunk_name[0]) || isnonalpha(chunk_name[1]) ||
@@ -2479,25 +2646,28 @@ png_check_chunk_name(png_structp png_ptr, png_bytep chunk_name)
 }
 
 /* Combines the row recently read in with the existing pixels in the
-   row.  This routine takes care of alpha and transparency if requested.
-   This routine also handles the two methods of progressive display
-   of interlaced images, depending on the mask value.
-   The mask value describes which pixels are to be combined with
-   the row.  The pattern always repeats every 8 pixels, so just 8
-   bits are needed.  A one indicates the pixel is to be combined,
-   a zero indicates the pixel is to be skipped.  This is in addition
-   to any alpha or transparency value associated with the pixel.  If
-   you want all pixels to be combined, pass 0xff (255) in mask.  */
+ * row.  This routine takes care of alpha and transparency if requested.
+ * This routine also handles the two methods of progressive display
+ * of interlaced images, depending on the mask value.
+ * The mask value describes which pixels are to be combined with
+ * the row.  The pattern always repeats every 8 pixels, so just 8
+ * bits are needed.  A one indicates the pixel is to be combined,
+ * a zero indicates the pixel is to be skipped.  This is in addition
+ * to any alpha or transparency value associated with the pixel.  If
+ * you want all pixels to be combined, pass 0xff (255) in mask.
+ */
 
 void /* PRIVATE */
 png_combine_row(png_structp png_ptr, png_bytep row, int mask)
 {
    png_debug(1, "in png_combine_row");
+
    if (mask == 0xff)
    {
       png_memcpy(row, png_ptr->row_buf + 1,
-         PNG_ROWBYTES(png_ptr->row_info.pixel_depth, png_ptr->width));
+          PNG_ROWBYTES(png_ptr->row_info.pixel_depth, png_ptr->width));
    }
+
    else
    {
       switch (png_ptr->row_info.pixel_depth)
@@ -2519,6 +2689,7 @@ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
                 s_end = 7;
                 s_inc = 1;
             }
+
             else
 #endif
             {
@@ -2546,16 +2717,19 @@ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
                   sp++;
                   dp++;
                }
+
                else
                   shift += s_inc;
 
                if (m == 1)
                   m = 0x80;
+
                else
                   m >>= 1;
             }
             break;
          }
+
          case 2:
          {
             png_bytep sp = png_ptr->row_buf + 1;
@@ -2574,6 +2748,7 @@ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
                s_end = 6;
                s_inc = 2;
             }
+
             else
 #endif
             {
@@ -2599,15 +2774,19 @@ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
                   sp++;
                   dp++;
                }
+
                else
                   shift += s_inc;
+
                if (m == 1)
                   m = 0x80;
+
                else
                   m >>= 1;
             }
             break;
          }
+
          case 4:
          {
             png_bytep sp = png_ptr->row_buf + 1;
@@ -2626,6 +2805,7 @@ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
                s_end = 4;
                s_inc = 4;
             }
+
             else
 #endif
             {
@@ -2650,15 +2830,19 @@ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
                   sp++;
                   dp++;
                }
+
                else
                   shift += s_inc;
+
                if (m == 1)
                   m = 0x80;
+
                else
                   m >>= 1;
             }
             break;
          }
+
          default:
          {
             png_bytep sp = png_ptr->row_buf + 1;
@@ -2668,7 +2852,6 @@ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
             png_uint_32 row_width = png_ptr->width;
             png_byte m = 0x80;
 
-
             for (i = 0; i < row_width; i++)
             {
                if (m & mask)
@@ -2681,6 +2864,7 @@ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
 
                if (m == 1)
                   m = 0x80;
+
                else
                   m >>= 1;
             }
@@ -2691,10 +2875,6 @@ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
 }
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
-/* OLD pre-1.0.9 interface:
-void png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
-   png_uint_32 transformations)
- */
 void /* PRIVATE */
 png_do_read_interlace(png_structp png_ptr)
 {
@@ -2735,6 +2915,7 @@ png_do_read_interlace(png_structp png_ptr)
                 s_end = 0;
                 s_inc = -1;
             }
+
             else
 #endif
             {
@@ -2752,24 +2933,29 @@ png_do_read_interlace(png_structp png_ptr)
                {
                   *dp &= (png_byte)((0x7f7f >> (7 - dshift)) & 0xff);
                   *dp |= (png_byte)(v << dshift);
+
                   if (dshift == s_end)
                   {
                      dshift = s_start;
                      dp--;
                   }
+
                   else
                      dshift += s_inc;
                }
+
                if (sshift == s_end)
                {
                   sshift = s_start;
                   sp--;
                }
+
                else
                   sshift += s_inc;
             }
             break;
          }
+
          case 2:
          {
             png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
@@ -2788,6 +2974,7 @@ png_do_read_interlace(png_structp png_ptr)
                s_end = 0;
                s_inc = -2;
             }
+
             else
 #endif
             {
@@ -2808,24 +2995,29 @@ png_do_read_interlace(png_structp png_ptr)
                {
                   *dp &= (png_byte)((0x3f3f >> (6 - dshift)) & 0xff);
                   *dp |= (png_byte)(v << dshift);
+
                   if (dshift == s_end)
                   {
                      dshift = s_start;
                      dp--;
                   }
+
                   else
                      dshift += s_inc;
                }
+
                if (sshift == s_end)
                {
                   sshift = s_start;
                   sp--;
                }
+
                else
                   sshift += s_inc;
             }
             break;
          }
+
          case 4:
          {
             png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 1);
@@ -2844,6 +3036,7 @@ png_do_read_interlace(png_structp png_ptr)
                s_end = 0;
                s_inc = -4;
             }
+
             else
 #endif
             {
@@ -2863,19 +3056,23 @@ png_do_read_interlace(png_structp png_ptr)
                {
                   *dp &= (png_byte)((0xf0f >> (4 - dshift)) & 0xff);
                   *dp |= (png_byte)(v << dshift);
+
                   if (dshift == s_end)
                   {
                      dshift = s_start;
                      dp--;
                   }
+
                   else
                      dshift += s_inc;
                }
+
                if (sshift == s_end)
                {
                   sshift = s_start;
                   sp--;
                }
+
                else
                   sshift += s_inc;
             }
@@ -2884,8 +3081,10 @@ png_do_read_interlace(png_structp png_ptr)
          default:
          {
             png_size_t pixel_bytes = (row_info->pixel_depth >> 3);
+
             png_bytep sp = row + (png_size_t)(row_info->width - 1)
                 * pixel_bytes;
+
             png_bytep dp = row + (png_size_t)(final_width - 1) * pixel_bytes;
 
             int jstop = png_pass_inc[pass];
@@ -2897,11 +3096,13 @@ png_do_read_interlace(png_structp png_ptr)
                int j;
 
                png_memcpy(v, sp, pixel_bytes);
+
                for (j = 0; j < jstop; j++)
                {
                   png_memcpy(dp, v, pixel_bytes);
                   dp -= pixel_bytes;
                }
+
                sp -= pixel_bytes;
             }
             break;
@@ -2911,26 +3112,27 @@ png_do_read_interlace(png_structp png_ptr)
       row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
    }
 #ifndef PNG_READ_PACKSWAP_SUPPORTED
-   transformations = transformations; /* Silence compiler warning */
+   PNG_UNUSED(transformations)  /* Silence compiler warning */
 #endif
 }
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
 
 void /* PRIVATE */
 png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
-   png_bytep prev_row, int filter)
+    png_const_bytep prev_row, int filter)
 {
    png_debug(1, "in png_read_filter_row");
-   png_debug2(2, "row = %lu, filter = %d", png_ptr->row_number, filter);
+   png_debug2(2, "row = %u, filter = %d", png_ptr->row_number, filter);
    switch (filter)
    {
       case PNG_FILTER_VALUE_NONE:
          break;
+
       case PNG_FILTER_VALUE_SUB:
       {
-         png_uint_32 i;
-         png_uint_32 istop = row_info->rowbytes;
-         png_uint_32 bpp = (row_info->pixel_depth + 7) >> 3;
+         png_size_t i;
+         png_size_t istop = row_info->rowbytes;
+         unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
          png_bytep rp = row + bpp;
          png_bytep lp = row;
 
@@ -2943,10 +3145,10 @@ png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
       }
       case PNG_FILTER_VALUE_UP:
       {
-         png_uint_32 i;
-         png_uint_32 istop = row_info->rowbytes;
+         png_size_t i;
+         png_size_t istop = row_info->rowbytes;
          png_bytep rp = row;
-         png_bytep pp = prev_row;
+         png_const_bytep pp = prev_row;
 
          for (i = 0; i < istop; i++)
          {
@@ -2957,37 +3159,39 @@ png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
       }
       case PNG_FILTER_VALUE_AVG:
       {
-         png_uint_32 i;
+         png_size_t i;
          png_bytep rp = row;
-         png_bytep pp = prev_row;
+         png_const_bytep pp = prev_row;
          png_bytep lp = row;
-         png_uint_32 bpp = (row_info->pixel_depth + 7) >> 3;
-         png_uint_32 istop = row_info->rowbytes - bpp;
+         unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
+         png_size_t istop = row_info->rowbytes - bpp;
 
          for (i = 0; i < bpp; i++)
          {
             *rp = (png_byte)(((int)(*rp) +
-               ((int)(*pp++) / 2 )) & 0xff);
+                ((int)(*pp++) / 2 )) & 0xff);
+
             rp++;
          }
 
          for (i = 0; i < istop; i++)
          {
             *rp = (png_byte)(((int)(*rp) +
-               (int)(*pp++ + *lp++) / 2 ) & 0xff);
+                (int)(*pp++ + *lp++) / 2 ) & 0xff);
+
             rp++;
          }
          break;
       }
       case PNG_FILTER_VALUE_PAETH:
       {
-         png_uint_32 i;
+         png_size_t i;
          png_bytep rp = row;
-         png_bytep pp = prev_row;
+         png_const_bytep pp = prev_row;
          png_bytep lp = row;
-         png_bytep cp = prev_row;
-         png_uint_32 bpp = (row_info->pixel_depth + 7) >> 3;
-         png_uint_32 istop=row_info->rowbytes - bpp;
+         png_const_bytep cp = prev_row;
+         unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
+         png_size_t istop=row_info->rowbytes - bpp;
 
          for (i = 0; i < bpp; i++)
          {
@@ -3019,8 +3223,10 @@ png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
             /*
                if (pa <= pb && pa <= pc)
                   p = a;
+
                else if (pb <= pc)
                   p = b;
+
                else
                   p = c;
              */
@@ -3033,8 +3239,8 @@ png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
          break;
       }
       default:
-         png_warning(png_ptr, "Ignoring bad adaptive filter type");
-         *row = 0;
+         png_error(png_ptr, "Ignoring bad adaptive filter type");
+         /*NOT REACHED */
          break;
    }
 }
@@ -3068,13 +3274,16 @@ png_read_finish_row(png_structp png_ptr)
    if (png_ptr->interlaced)
    {
       png_ptr->row_number = 0;
-      png_memset(png_ptr->prev_row, 0,
-         png_ptr->rowbytes + 1);
+
+      png_memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
+
       do
       {
          png_ptr->pass++;
+
          if (png_ptr->pass >= 7)
             break;
+
          png_ptr->iwidth = (png_ptr->width +
             png_pass_inc[png_ptr->pass] - 1 -
             png_pass_start[png_ptr->pass]) /
@@ -3083,15 +3292,15 @@ png_read_finish_row(png_structp png_ptr)
          if (!(png_ptr->transformations & PNG_INTERLACE))
          {
             png_ptr->num_rows = (png_ptr->height +
-               png_pass_yinc[png_ptr->pass] - 1 -
-               png_pass_ystart[png_ptr->pass]) /
-               png_pass_yinc[png_ptr->pass];
-            if (!(png_ptr->num_rows))
-               continue;
+                png_pass_yinc[png_ptr->pass] - 1 -
+                png_pass_ystart[png_ptr->pass]) /
+                png_pass_yinc[png_ptr->pass];
          }
+
          else  /* if (png_ptr->transformations & PNG_INTERLACE) */
-            break;
-      } while (png_ptr->iwidth == 0);
+            break; /* libpng deinterlacing sees every row */
+
+      } while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0);
 
       if (png_ptr->pass < 7)
          return;
@@ -3106,44 +3315,45 @@ png_read_finish_row(png_structp png_ptr)
 
       png_ptr->zstream.next_out = (Byte *)&extra;
       png_ptr->zstream.avail_out = (uInt)1;
+
       for (;;)
       {
          if (!(png_ptr->zstream.avail_in))
          {
             while (!png_ptr->idat_size)
             {
-               png_byte chunk_length[4];
-
                png_crc_finish(png_ptr, 0);
-
-               png_read_data(png_ptr, chunk_length, 4);
-               png_ptr->idat_size = png_get_uint_31(png_ptr, chunk_length);
-               png_reset_crc(png_ptr);
-               png_crc_read(png_ptr, png_ptr->chunk_name, 4);
+               png_ptr->idat_size = png_read_chunk_header(png_ptr);
                if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
                   png_error(png_ptr, "Not enough image data");
-
             }
+
             png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
             png_ptr->zstream.next_in = png_ptr->zbuf;
+
             if (png_ptr->zbuf_size > png_ptr->idat_size)
                png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size;
+
             png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zstream.avail_in);
             png_ptr->idat_size -= png_ptr->zstream.avail_in;
          }
+
          ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
+
          if (ret == Z_STREAM_END)
          {
             if (!(png_ptr->zstream.avail_out) || png_ptr->zstream.avail_in ||
-               png_ptr->idat_size)
+                png_ptr->idat_size)
                png_warning(png_ptr, "Extra compressed data");
+
             png_ptr->mode |= PNG_AFTER_IDAT;
             png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
             break;
          }
+
          if (ret != Z_OK)
             png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
-                      "Decompression Error");
+                "Decompression Error");
 
          if (!(png_ptr->zstream.avail_out))
          {
@@ -3196,21 +3406,24 @@ png_read_start_row(png_structp png_ptr)
    {
       if (!(png_ptr->transformations & PNG_INTERLACE))
          png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
-            png_pass_ystart[0]) / png_pass_yinc[0];
+             png_pass_ystart[0]) / png_pass_yinc[0];
+
       else
          png_ptr->num_rows = png_ptr->height;
 
       png_ptr->iwidth = (png_ptr->width +
-         png_pass_inc[png_ptr->pass] - 1 -
-         png_pass_start[png_ptr->pass]) /
-         png_pass_inc[png_ptr->pass];
+          png_pass_inc[png_ptr->pass] - 1 -
+          png_pass_start[png_ptr->pass]) /
+          png_pass_inc[png_ptr->pass];
    }
+
    else
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
    {
       png_ptr->num_rows = png_ptr->height;
       png_ptr->iwidth = png_ptr->width;
    }
+
    max_pixel_depth = png_ptr->pixel_depth;
 
 #ifdef PNG_READ_PACK_SUPPORTED
@@ -3225,16 +3438,20 @@ png_read_start_row(png_structp png_ptr)
       {
          if (png_ptr->num_trans)
             max_pixel_depth = 32;
+
          else
             max_pixel_depth = 24;
       }
+
       else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
       {
          if (max_pixel_depth < 8)
             max_pixel_depth = 8;
+
          if (png_ptr->num_trans)
             max_pixel_depth *= 2;
       }
+
       else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
       {
          if (png_ptr->num_trans)
@@ -3251,17 +3468,21 @@ png_read_start_row(png_structp png_ptr)
    {
       if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
          max_pixel_depth = 32;
+
       else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
       {
          if (max_pixel_depth <= 8)
             max_pixel_depth = 16;
+
          else
             max_pixel_depth = 32;
       }
+
       else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
       {
          if (max_pixel_depth <= 32)
             max_pixel_depth = 32;
+
          else
             max_pixel_depth = 64;
       }
@@ -3273,29 +3494,34 @@ png_read_start_row(png_structp png_ptr)
    {
       if (
 #ifdef PNG_READ_EXPAND_SUPPORTED
-        (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) ||
+          (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) ||
 #endif
 #ifdef PNG_READ_FILLER_SUPPORTED
-        (png_ptr->transformations & (PNG_FILLER)) ||
+          (png_ptr->transformations & (PNG_FILLER)) ||
 #endif
-        png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+          png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
       {
          if (max_pixel_depth <= 16)
             max_pixel_depth = 32;
+
          else
             max_pixel_depth = 64;
       }
+
       else
       {
          if (max_pixel_depth <= 8)
-           {
-             if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+         {
+            if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
                max_pixel_depth = 32;
-             else
+
+            else
                max_pixel_depth = 24;
-           }
+         }
+
          else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
             max_pixel_depth = 64;
+
          else
             max_pixel_depth = 48;
       }
@@ -3305,12 +3531,13 @@ png_read_start_row(png_structp png_ptr)
 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    if (png_ptr->transformations & PNG_USER_TRANSFORM)
-     {
-       int user_pixel_depth = png_ptr->user_transform_depth*
+   {
+      int user_pixel_depth = png_ptr->user_transform_depth*
          png_ptr->user_transform_channels;
-       if (user_pixel_depth > max_pixel_depth)
+
+      if (user_pixel_depth > max_pixel_depth)
          max_pixel_depth=user_pixel_depth;
-     }
+   }
 #endif
 
    /* Align the width on the next larger 8 pixels.  Mainly used
@@ -3321,7 +3548,8 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
     * for safety's sake
     */
    row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
-      1 + ((max_pixel_depth + 7) >> 3);
+       1 + ((max_pixel_depth + 7) >> 3);
+
 #ifdef PNG_MAX_MALLOC_64K
    if (row_bytes > (png_uint_32)65536L)
       png_error(png_ptr, "This image requires a row greater than 64KB");
@@ -3330,20 +3558,24 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
    {
      png_free(png_ptr, png_ptr->big_row_buf);
+
      if (png_ptr->interlaced)
         png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
             row_bytes + 48);
+
      else
         png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr,
             row_bytes + 48);
+
      png_ptr->old_big_row_buf_size = row_bytes + 48;
 
 #ifdef PNG_ALIGNED_MEMORY_SUPPORTED
      /* Use 16-byte aligned memory for row_buf with at least 16 bytes
       * of padding before and after row_buf.
       */
-     png_ptr->row_buf = png_ptr->big_row_buf + 32
-         - (((png_alloc_size_t)&(png_ptr->big_row_buf[0]) + 15) % 16);
+     png_ptr->row_buf = png_ptr->big_row_buf + 32 -
+         (((png_alloc_size_t)png_ptr->big_row_buf + 15) & 0x0F);
+
      png_ptr->old_big_row_buf_size = row_bytes + 48;
 #else
      /* Use 32 bytes of padding before and 16 bytes after row_buf. */
@@ -3353,28 +3585,30 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    }
 
 #ifdef PNG_MAX_MALLOC_64K
-   if ((png_uint_32)png_ptr->rowbytes + 1 > (png_uint_32)65536L)
+   if (png_ptr->rowbytes > 65535)
       png_error(png_ptr, "This image requires a row greater than 64KB");
+
 #endif
-   if ((png_uint_32)png_ptr->rowbytes > (png_uint_32)(PNG_SIZE_MAX - 1))
+   if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
       png_error(png_ptr, "Row has too many bytes to allocate in memory");
 
    if (png_ptr->rowbytes + 1 > png_ptr->old_prev_row_size)
    {
       png_free(png_ptr, png_ptr->prev_row);
-      png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, (png_uint_32)(
-        png_ptr->rowbytes + 1));
+
+      png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, png_ptr->rowbytes + 1);
+
       png_ptr->old_prev_row_size = png_ptr->rowbytes + 1;
    }
 
    png_memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
 
-   png_debug1(3, "width = %lu,", png_ptr->width);
-   png_debug1(3, "height = %lu,", png_ptr->height);
-   png_debug1(3, "iwidth = %lu,", png_ptr->iwidth);
-   png_debug1(3, "num_rows = %lu,", png_ptr->num_rows);
-   png_debug1(3, "rowbytes = %lu,", png_ptr->rowbytes);
-   png_debug1(3, "irowbytes = %lu",
+   png_debug1(3, "width = %u,", png_ptr->width);
+   png_debug1(3, "height = %u,", png_ptr->height);
+   png_debug1(3, "iwidth = %u,", png_ptr->iwidth);
+   png_debug1(3, "num_rows = %u,", png_ptr->num_rows);
+   png_debug1(3, "rowbytes = %u,", png_ptr->rowbytes);
+   png_debug1(3, "irowbytes = %u",
        PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
 
    png_ptr->flags |= PNG_FLAG_ROW_INIT;