[libpng16] Attempt to detect configuration issues with pngdeflate,

which requires both the correct libpng and the correct zlib to function
correctly.

ANNOUNCE

@@ -69,6 +69,8 @@ Version 1.6.3beta05 [May 8, 2013]
     Added a call to png_set_packing()
     Initialize dimension values so if sscanf fails at least we have known
       invalid values.
+  Attempt to detect configuration issues with pngdeflate, which requires
+    both the correct libpng and the correct zlib to function correctly.
 
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CHANGES

@@ -4552,6 +4552,8 @@ Version 1.6.3beta05 [May 8, 2013]
     Added a call to png_set_packing()
     Initialize dimension values so if sscanf fails at least we have known
       invalid values.
+  Attempt to detect configuration issues with pngdeflate, which requires
+    both the correct libpng and the correct zlib to function correctly.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

Makefile.am

@@ -188,7 +188,8 @@ endif
 $(srcdir)/scripts/pnglibconf.h.prebuilt:
 	@echo "Attempting to build $@" >&2
 	@echo "This is a machine generated file, but if you want to make" >&2
-	@echo "a new one simply make 'scripts/pnglibconf.out' and copy that" >&2
+	@echo "a new one simply make 'scripts/pnglibconf.out', copy that" >&2
+	@echo "AND set PNG_ZLIB_VERNUM to 0 (you MUST do this)" >&2
 	@exit 1
 
 # The following is necessary to ensure that the local pnglibconf.h is used, not

contrib/tools/pngdeflate.c

@@ -25,20 +25,19 @@
 #  include "../../png.h"
 #endif
 
-#if PNG_LIBPNG_VER < 10600 /* 1.6.0 */
-#  error pngdeflate will not work with libpng versions prior to 1.6
+#if PNG_LIBPNG_VER < 10603 /* 1.6.3 */
+#  error pngdeflate will not work with libpng versions prior to 1.6.3
 #endif
 
 #ifdef PNG_READ_SUPPORTED
 #include <zlib.h>
 
 #ifndef PNG_MAXIMUM_INFLATE_WINDOW
-#  if PNG_LIBPNG_VER != 10600 && PNG_LIBPNG_VER != 10601 && \
-      PNG_LIBPNG_VER != 10602
-#     error pngdeflate not supported in this libpng version
-#  endif
+#  error pngdeflate not supported in this libpng version
 #endif
 
+#if PNG_ZLIB_VERNUM >= 0x1240
+
 /* Copied from pngpriv.h */
 #ifdef __cplusplus
 #  define png_voidcast(type, value) static_cast<type>(value)
@@ -726,8 +725,8 @@ fix_one(FILE *fp, FILE *fpIn, IDAT_info *info, png_uint_32 max_IDAT, int strip)
                      break;
                   /* Fall trhough */
 
-               default: /* Keep only IHDR, PLTE */
-                  if (tag == png_IHDR || tag == png_PLTE)
+               default: /* Keep only IHDR, PLTE, tRNS */
+                  if (tag == png_IHDR || tag == png_PLTE || tag == png_tRNS)
                      break;
 
                   skip = 1;
@@ -994,8 +993,8 @@ usage(const char *prog, int rc)
 #  endif
       "  --optimize (-o): Find the smallest deflate window size for the file.\n"
       "                   Also outputs a summary for each file.\n"
-      "  --strip (-s): Remove chunks except for IHDR, PLTE, IEND, gAMA, sRGB.\n"
-      "                If given twice remove gAMA and sRGB as well.\n"
+      "  --strip (-s): Remove chunks except for IHDR, PLTE, IEND, tRNS, gAMA,\n"
+      "                sRGB.  If given twice remove gAMA and sRGB as well.\n"
       "  --errors (-e): Output errors from libpng (except too-far-back).\n");
    fprintf(stderr,
       "  --warnings (-w): Output warnings from libpng.\n"
@@ -1169,6 +1168,16 @@ main(int argc, const char **argv)
    return err != 0;
 }
 
+#else /* PNG_ZLIB_VERNUM < 0x1240 */
+int
+main(void)
+{
+   fprintf(stderr, "pngdeflate needs libpng with a zlib >=1.2.4 (not 0x%x)\n",
+      PNG_ZLIB_VERNUM);
+   return 77;
+}
+#endif /* PNG_ZLIB_VERNUM */
+
 #else /* No read support */
 
 int

pngrutil.c

@@ -367,7 +367,7 @@ png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
     */
    {
       int ret; /* zlib return code */
-#     if ZLIB_VERNUM >= 0x1240
+#     if PNG_ZLIB_VERNUM >= 0x1240
 
 #        if defined(PNG_SET_OPTION_SUPPORTED) && \
             defined(PNG_MAXIMUM_INFLATE_WINDOW)
@@ -394,7 +394,7 @@ png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
 
       if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED)
       {
-#        if ZLIB_VERNUM < 0x1240
+#        if PNG_ZLIB_VERNUM < 0x1240
             ret = inflateReset(&png_ptr->zstream);
 #        else
             ret = inflateReset2(&png_ptr->zstream, window_bits);
@@ -403,7 +403,7 @@ png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
 
       else
       {
-#        if ZLIB_VERNUM < 0x1240
+#        if PNG_ZLIB_VERNUM < 0x1240
             ret = inflateInit(&png_ptr->zstream);
 #        else
             ret = inflateInit2(&png_ptr->zstream, window_bits);

scripts/pnglibconf.dfa

@@ -238,6 +238,7 @@ option ARM_NEON_CHECK disabled enables ARM_NEON
 setting Z_DEFAULT_COMPRESSION default @Z_DEFAULT_COMPRESSION
 setting Z_DEFAULT_STRATEGY default @Z_FILTERED
 setting Z_DEFAULT_NOFILTER_STRATEGY default @Z_DEFAULT_STRATEGY
+setting ZLIB_VERNUM default @ZLIB_VERNUM
 
 setting TEXT_Z_DEFAULT_COMPRESSION default @Z_DEFAULT_COMPRESSION
 setting TEXT_Z_DEFAULT_STRATEGY default @Z_DEFAULT_STRATEGY

scripts/pnglibconf.h.prebuilt

@@ -202,6 +202,7 @@
 #define PNG_TEXT_Z_DEFAULT_STRATEGY 0
 #define PNG_WEIGHT_SHIFT 8
 #define PNG_ZBUF_SIZE 8192
+#define PNG_ZLIB_VERNUM 0 /* unknown */
 #define PNG_Z_DEFAULT_COMPRESSION (-1)
 #define PNG_Z_DEFAULT_NOFILTER_STRATEGY 0
 #define PNG_Z_DEFAULT_STRATEGY 1