/* pngvalid.c - validate libpng by constructing then reading png files. * * Last changed in libpng 1.5.0 [August 26, 2010] * Copyright (c) 2010 Glenn Randers-Pehrson * Written by John C. Bowler * * This code is released under the libpng license. * For conditions of distribution and use, see the disclaimer * and license in png.h * * NOTES: * This is a C program that is intended to be linked against libpng. It * generates bitmaps internally, stores them as PNG files (using the * sequential write code) then reads them back (using the sequential * read code) and validates that the result has the correct data. * * The program can be modified and extended to test the correctness of * transformations performed by libpng. */ #include "png.h" #include "zlib.h" /* For crc32 */ #include /* For malloc */ #include /* For memcpy, memset */ #include /* For floor */ /* Unused formal parameter errors are removed using the following macro which is * expected to have no bad effects on performance. */ #ifndef UNUSED # define UNUSED(param) param = param; #endif /***************************** EXCEPTION HANDLING *****************************/ #include "contrib/visupng/cexcept.h" struct png_store; define_exception_type(struct png_store*); /* The following are macros to reduce typing everywhere where the well known * name 'the_exception_context' must be defined. */ #define anon_context(ps) struct exception_context *the_exception_context = \ &(ps)->exception_context #define context(ps,fault) anon_context(ps); png_store *fault /******************************* ERROR UTILITIES ******************************/ static size_t safecat(char *buffer, size_t bufsize, size_t pos, PNG_CONST char *cat) { while (pos < bufsize && cat != NULL && *cat != 0) buffer[pos++] = *cat++; if (pos >= bufsize) pos = bufsize-1; buffer[pos] = 0; return pos; } static size_t safecatn(char *buffer, size_t bufsize, size_t pos, int n) { char number[64]; sprintf(number, "%d", n); return safecat(buffer, bufsize, pos, number); } static size_t safecatd(char *buffer, size_t bufsize, size_t pos, double d, int precision) { char number[64]; sprintf(number, "%.*f", precision, d); return safecat(buffer, bufsize, pos, number); } static PNG_CONST char invalid[] = "invalid"; static PNG_CONST char sep[] = ": "; /* NOTE: this is indexed by ln2(bit_depth)! */ static PNG_CONST char *bit_depths[8] = { "1", "2", "4", "8", "16", invalid, invalid, invalid }; static PNG_CONST char *colour_types[8] = { "greyscale", invalid, "truecolour", "indexed-colour", "greyscale with alpha", invalid, "truecolour with alpha", invalid }; /* To get log-bit-depth from bit depth, returns 0 to 7 (7 on error). */ static unsigned int log2depth(png_byte bit_depth) { switch (bit_depth) { case 1: return 0; case 2: return 1; case 4: return 2; case 8: return 3; case 16: return 4; default: return 7; } } /* A numeric ID based on PNG file characteristics: */ #define FILEID(col, depth, interlace) \ ((png_uint_32)((col) + ((depth)<<3)) + ((interlace)<<8)) #define COL_FROM_ID(id) ((png_byte)((id)& 0x7U)) #define DEPTH_FROM_ID(id) ((png_byte)(((id) >> 3) & 0x1fU)) #define INTERLACE_FROM_ID(id) ((int)(((id) >> 8) & 0xff)) /* Utility to construct a standard name for a standard image. */ static size_t standard_name(char *buffer, size_t bufsize, size_t pos, png_byte colour_type, int log_bit_depth, int interlace_type) { pos = safecat(buffer, bufsize, pos, colour_types[colour_type]); pos = safecat(buffer, bufsize, pos, " "); pos = safecat(buffer, bufsize, pos, bit_depths[log_bit_depth]); pos = safecat(buffer, bufsize, pos, " bit"); if (interlace_type != PNG_INTERLACE_NONE) pos = safecat(buffer, bufsize, pos, " interlaced"); return pos; } static size_t standard_name_from_id(char *buffer, size_t bufsize, size_t pos, png_uint_32 id) { return standard_name(buffer, bufsize, pos, COL_FROM_ID(id), log2depth(DEPTH_FROM_ID(id)), INTERLACE_FROM_ID(id)); } /* Convenience API and defines to list valid formats. Note that 16 bit read and * write support is required to do 16 bit read tests (we must be able to make a * 16 bit image to test!) */ #ifdef PNG_WRITE_16BIT_SUPPORTED # define WRITE_BDHI 4 # ifdef PNG_READ_16BIT_SUPPORTED # define READ_BDHI 4 # define DO_16BIT # endif #else # define WRITE_BDHI 3 #endif #ifndef DO_16BIT # define READ_BDHI 3 #endif static int next_format(png_bytep colour_type, png_bytep bit_depth) { if (*bit_depth == 0) { *colour_type = 0, *bit_depth = 1; return 1; } *bit_depth = (png_byte)(*bit_depth << 1); /* Palette images are restricted to 8 bit depth */ if (*bit_depth <= 8 # ifdef DO_16BIT || (*colour_type != 3 && *bit_depth <= 16) # endif ) return 1; /* Move to the next color type, or return 0 at the end. */ switch (*colour_type) { case 0: *colour_type = 2; *bit_depth = 8; return 1; case 2: *colour_type = 3; *bit_depth = 1; return 1; case 3: *colour_type = 4; *bit_depth = 8; return 1; case 4: *colour_type = 6; *bit_depth = 8; return 1; default: return 0; } } static unsigned int sample(png_const_bytep row, png_byte colour_type, png_byte bit_depth, png_uint_32 x, unsigned int sample) { png_uint_32 index, result; /* Find a sample index for the desired sample: */ x *= bit_depth; index = x; if ((colour_type & 1) == 0) /* !palette */ { if (colour_type & 2) index *= 3, index += sample; /* Colour channels; select one */ if (colour_type & 4) index += x; /* Alpha channel */ } /* Return the sample from the row as an integer. */ row += index >> 3; result = *row; if (bit_depth == 8) return result; else if (bit_depth > 8) return (result << 8) + *++row; /* Less than 8 bits per sample. */ index &= 7; return (result >> (8-index-bit_depth)) & ((1U<> (20-8)) ^ ((u1 << 7) | (u0 >> (32-7)))) & 0xff; u1 <<= 8; u1 |= u0 >> 24; u0 <<= 8; u0 |= u; *mark++ = (png_byte)u; } } static void store_pool_init(png_store *ps, store_pool *pool) { memset(pool, 0, sizeof *pool); pool->store = ps; pool->list = NULL; pool->max = pool->current = pool->limit = pool->total = 0; pool->max_max = pool->max_limit = pool->max_total = 0; store_pool_mark(pool->mark); } static void store_init(png_store* ps) { memset(ps, 0, sizeof *ps); init_exception_context(&ps->exception_context); store_pool_init(ps, &ps->read_memory_pool); store_pool_init(ps, &ps->write_memory_pool); ps->verbose = 0; ps->treat_warnings_as_errors = 0; ps->expect_error = 0; ps->expect_warning = 0; ps->saw_warning = 0; ps->speed = 0; ps->progressive = 0; ps->validated = 0; ps->nerrors = ps->nwarnings = 0; ps->pread = NULL; ps->piread = NULL; ps->saved = ps->current = NULL; ps->next = NULL; ps->readpos = 0; ps->image = NULL; ps->cb_image = 0; ps->pwrite = NULL; ps->piwrite = NULL; ps->writepos = 0; ps->new.prev = NULL; } /* This somewhat odd function is used when reading an image to ensure that the * buffer is big enough - this is why a png_structp is available. */ static void store_ensure_image(png_store *ps, png_structp pp, size_t cb) { if (ps->cb_image < cb) { if (ps->image != NULL) { free(ps->image-1); ps->cb_image = 0; } /* The buffer is deliberately mis-aligned. */ ps->image = malloc(cb+1); if (ps->image == NULL) png_error(pp, "OOM allocating image buffer"); ++(ps->image); ps->cb_image = cb; } } static void store_freebuffer(png_store_buffer* psb) { if (psb->prev) { store_freebuffer(psb->prev); free(psb->prev); psb->prev = NULL; } } static void store_freenew(png_store *ps) { store_freebuffer(&ps->new); ps->writepos = 0; } static void store_storenew(png_store *ps) { png_store_buffer *pb; if (ps->writepos != STORE_BUFFER_SIZE) png_error(ps->pwrite, "invalid store call"); pb = malloc(sizeof *pb); if (pb == NULL) png_error(ps->pwrite, "store new: OOM"); *pb = ps->new; ps->new.prev = pb; ps->writepos = 0; } static void store_freefile(png_store_file **ppf) { if (*ppf != NULL) { store_freefile(&(*ppf)->next); store_freebuffer(&(*ppf)->data); (*ppf)->datacount = 0; free(*ppf); *ppf = NULL; } } /* Main interface to file storeage, after writing a new PNG file (see the API * below) call store_storefile to store the result with the given name and id. */ static void store_storefile(png_store *ps, png_uint_32 id) { png_store_file *pf = malloc(sizeof *pf); if (pf == NULL) png_error(ps->pwrite, "storefile: OOM"); safecat(pf->name, sizeof pf->name, 0, ps->wname); pf->id = id; pf->data = ps->new; pf->datacount = ps->writepos; ps->new.prev = NULL; ps->writepos = 0; /* And save it. */ pf->next = ps->saved; ps->saved = pf; } /* Generate an error message (in the given buffer) */ static size_t store_message(png_store *ps, png_structp pp, char *buffer, size_t bufsize, size_t pos, PNG_CONST char *msg) { if (pp != NULL && pp == ps->pread) { /* Reading a file */ pos = safecat(buffer, bufsize, pos, "read: "); if (ps->current != NULL) { pos = safecat(buffer, bufsize, pos, ps->current->name); pos = safecat(buffer, bufsize, pos, sep); } } else if (pp != NULL && pp == ps->pwrite) { /* Writing a file */ pos = safecat(buffer, bufsize, pos, "write: "); pos = safecat(buffer, bufsize, pos, ps->wname); pos = safecat(buffer, bufsize, pos, sep); } else { /* Neither reading nor writing (or a memory error in struct delete) */ pos = safecat(buffer, bufsize, pos, "pngvalid: "); } if (ps->test[0] != 0) { pos = safecat(buffer, bufsize, pos, ps->test); pos = safecat(buffer, bufsize, pos, sep); } pos = safecat(buffer, bufsize, pos, msg); return pos; } /* Log an error or warning - the relevant count is always incremented. */ static void store_log(png_store* ps, png_structp pp, png_const_charp message, int is_error) { /* The warning is copied to the error buffer if there are no errors and it is * the first warning. The error is copied to the error buffer if it is the * first error (overwriting any prior warnings). */ if (is_error ? (ps->nerrors)++ == 0 : (ps->nwarnings)++ == 0 && ps->nerrors == 0) store_message(ps, pp, ps->error, sizeof ps->error, 0, message); if (ps->verbose) { char buffer[256]; size_t pos; if (is_error) pos = safecat(buffer, sizeof buffer, 0, "error: "); else pos = safecat(buffer, sizeof buffer, 0, "warning: "); store_message(ps, pp, buffer, sizeof buffer, pos, message); fputs(buffer, stderr); fputc('\n', stderr); } } /* Functions to use as PNG callbacks. */ static void store_error(png_structp pp, png_const_charp message) /* PNG_NORETURN */ { png_store *ps = png_get_error_ptr(pp); if (!ps->expect_error) store_log(ps, pp, message, 1/*error*/); /* And finally throw an exception. */ { struct exception_context *the_exception_context = &ps->exception_context; Throw ps; } } static void store_warning(png_structp pp, png_const_charp message) { png_store *ps = png_get_error_ptr(pp); if (!ps->expect_warning) store_log(ps, pp, message, 0/*warning*/); else ps->saw_warning = 1; } static void store_write(png_structp pp, png_bytep pb, png_size_t st) { png_store *ps = png_get_io_ptr(pp); if (ps->pwrite != pp) png_error(pp, "store state damaged"); while (st > 0) { size_t cb; if (ps->writepos >= STORE_BUFFER_SIZE) store_storenew(ps); cb = st; if (cb > STORE_BUFFER_SIZE - ps->writepos) cb = STORE_BUFFER_SIZE - ps->writepos; memcpy(ps->new.buffer + ps->writepos, pb, cb); pb += cb; st -= cb; ps->writepos += cb; } } static void store_flush(png_structp pp) { pp = pp; /*DOES NOTHING*/ } static size_t store_read_buffer_size(png_store *ps) { /* Return the bytes available for read in the current buffer. */ if (ps->next != &ps->current->data) return STORE_BUFFER_SIZE; return ps->current->datacount; } /* Return total bytes available for read. */ static size_t store_read_buffer_avail(png_store *ps) { if (ps->current != NULL && ps->next != NULL) { png_store_buffer *next = &ps->current->data; size_t cbAvail = ps->current->datacount; while (next != ps->next && next != NULL) { next = next->prev; cbAvail += STORE_BUFFER_SIZE; } if (next != ps->next) png_error(ps->pread, "buffer read error"); if (cbAvail > ps->readpos) return cbAvail - ps->readpos; } return 0; } static int store_read_buffer_next(png_store *ps) { png_store_buffer *pbOld = ps->next; png_store_buffer *pbNew = &ps->current->data; if (pbOld != pbNew) { while (pbNew != NULL && pbNew->prev != pbOld) pbNew = pbNew->prev; if (pbNew != NULL) { ps->next = pbNew; ps->readpos = 0; return 1; } png_error(ps->pread, "buffer lost"); } return 0; /* EOF or error */ } /* Need separate implementation and callback to allow use of the same code * during progressive read, where the io_ptr is set internally by libpng. */ static void store_read_imp(png_store *ps, png_bytep pb, png_size_t st) { if (ps->current == NULL || ps->next == NULL) png_error(ps->pread, "store state damaged"); while (st > 0) { size_t cbAvail = store_read_buffer_size(ps) - ps->readpos; if (cbAvail > 0) { if (cbAvail > st) cbAvail = st; memcpy(pb, ps->next->buffer + ps->readpos, cbAvail); st -= cbAvail; pb += cbAvail; ps->readpos += cbAvail; } else if (!store_read_buffer_next(ps)) png_error(ps->pread, "read beyond end of file"); } } static void store_read(png_structp pp, png_bytep pb, png_size_t st) { png_store *ps = png_get_io_ptr(pp); if (ps == NULL || ps->pread != pp) png_error(pp, "bad store read call"); store_read_imp(ps, pb, st); } static void store_progressive_read(png_store *ps, png_structp pp, png_infop pi) { /* Notice that a call to store_read will cause this function to fail because * readpos will be set. */ if (ps->pread != pp || ps->current == NULL || ps->next == NULL) png_error(pp, "store state damaged (progressive)"); do { if (ps->readpos != 0) png_error(pp, "store_read called during progressive read"); png_process_data(pp, pi, ps->next->buffer, store_read_buffer_size(ps)); } while (store_read_buffer_next(ps)); } /***************************** MEMORY MANAGEMENT*** ***************************/ /* A store_memory is simply the header for an allocated block of memory. The * pointer returned to libpng is just after the end of the header block, the * allocated memory is followed by a second copy of the 'mark'. */ typedef struct store_memory { store_pool *pool; /* Originating pool */ struct store_memory *next; /* Singly linked list */ png_alloc_size_t size; /* Size of memory allocated */ png_byte mark[4]; /* ID marker */ } store_memory; /* Handle a fatal error in memory allocation. This calls png_error if the * libpng struct is non-NULL, else it outputs a message and returns. This means * that a memory problem while libpng is running will abort (png_error) the * handling of particular file while one in cleanup (after the destroy of the * struct has returned) will simply keep going and free (or attempt to free) * all the memory. */ static void store_pool_error(png_store *ps, png_structp pp, PNG_CONST char *msg) { if (pp != NULL) png_error(pp, msg); /* Else we have to do it ourselves. png_error eventually calls store_log, * above. store_log accepts a NULL png_structp - it just changes what gets * output by store_message. */ store_log(ps, pp, msg, 1/*error*/); } static void store_memory_free(png_structp pp, store_pool *pool, store_memory *memory) { /* Note that pp may be NULL (see store_pool_delete below), the caller has * found 'memory' in pool->list *and* unlinked this entry, so this is a valid * pointer (for sure), but the contents may have been trashed. */ if (memory->pool != pool) store_pool_error(pool->store, pp, "memory corrupted (pool)"); else if (memcmp(memory->mark, pool->mark, sizeof memory->mark) != 0) store_pool_error(pool->store, pp, "memory corrupted (start)"); /* It should be safe to read the size field now. */ else { png_alloc_size_t cb = memory->size; if (cb > pool->max) store_pool_error(pool->store, pp, "memory corrupted (size)"); else if (memcmp((png_bytep)(memory+1)+cb, pool->mark, sizeof pool->mark) != 0) store_pool_error(pool->store, pp, "memory corrupted (end)"); /* Finally give the library a chance to find problems too: */ else { pool->current -= cb; free(memory); } } } static void store_pool_delete(png_store *ps, store_pool *pool) { if (pool->list != NULL) { fprintf(stderr, "%s: %s %s: memory lost (list follows):\n", ps->test, pool == &ps->read_memory_pool ? "read" : "write", pool == &ps->read_memory_pool ? (ps->current != NULL ? ps->current->name : "unknown file") : ps->wname); ++ps->nerrors; do { store_memory *next = pool->list; pool->list = next->next; next->next = NULL; fprintf(stderr, "\t%ud bytes @ %p\n", next->size, next+1); /* The NULL means this will always return, even if the memory is * corrupted. */ store_memory_free(NULL, pool, next); } while (pool->list != NULL); } /* And reset the other fields too for the next time. */ if (pool->max > pool->max_max) pool->max_max = pool->max; pool->max = 0; if (pool->current != 0) /* unexpected internal error */ fprintf(stderr, "%s: %s %s: memory counter mismatch (internal error)\n", ps->test, pool == &ps->read_memory_pool ? "read" : "write", pool == &ps->read_memory_pool ? (ps->current != NULL ? ps->current->name : "unknown file") : ps->wname); pool->current = 0; if (pool->limit > pool->max_limit) pool->max_limit = pool->limit; pool->limit = 0; if (pool->total > pool->max_total) pool->max_total = pool->total; pool->total = 0; /* Get a new mark too. */ store_pool_mark(pool->mark); } /* The memory callbacks: */ static png_voidp store_malloc(png_structp pp, png_alloc_size_t cb) { store_pool *pool = png_get_mem_ptr(pp); store_memory *new = malloc(cb + (sizeof *new) + (sizeof pool->mark)); if (new != NULL) { if (cb > pool->max) pool->max = cb; pool->current += cb; if (pool->current > pool->limit) pool->limit = pool->current; pool->total += cb; new->size = cb; memcpy(new->mark, pool->mark, sizeof new->mark); memcpy((png_byte*)(new+1) + cb, pool->mark, sizeof pool->mark); new->pool = pool; new->next = pool->list; pool->list = new; ++new; } else store_pool_error(pool->store, pp, "out of memory"); return new; } static void store_free(png_structp pp, png_voidp memory) { store_pool *pool = png_get_mem_ptr(pp); store_memory *this = memory, **test; /* First check that this 'memory' really is valid memory - it must be in the * pool list. If it is use the shared memory_free function to free it. */ --this; for (test = &pool->list; *test != this; test = &(*test)->next) { if (*test == NULL) { store_pool_error(pool->store, pp, "bad pointer to free"); return; } } /* Unlink this entry, *test == this. */ *test = this->next; this->next = NULL; store_memory_free(pp, pool, this); } /* Setup functions. */ /* Cleanup when aborting a write or after storing the new file. */ static void store_write_reset(png_store *ps) { if (ps->pwrite != NULL) { anon_context(ps); Try png_destroy_write_struct(&ps->pwrite, &ps->piwrite); Catch_anonymous { /* memory corruption: continue. */ } ps->pwrite = NULL; ps->piwrite = NULL; } /* And make sure that all the memory has been freed - this will output * spurious errors in the case of memory corruption above, but this is safe. */ store_pool_delete(ps, &ps->write_memory_pool); store_freenew(ps); } /* The following is the main write function, it returns a png_struct and, * optionally, a png)info suitable for writiing a new PNG file. Use * store_storefile above to record this file after it has been written. The * returned libpng structures as destroyed by store_write_reset above. */ static png_structp set_store_for_write(png_store *ps, png_infopp ppi, PNG_CONST char * volatile name) { anon_context(ps); Try { if (ps->pwrite != NULL) png_error(ps->pwrite, "write store already in use"); store_write_reset(ps); safecat(ps->wname, sizeof ps->wname, 0, name); /* Don't do the slow memory checks if doing a speed test. */ if (ps->speed) ps->pwrite = png_create_write_struct(PNG_LIBPNG_VER_STRING, ps, store_error, store_warning); else ps->pwrite = png_create_write_struct_2(PNG_LIBPNG_VER_STRING, ps, store_error, store_warning, &ps->write_memory_pool, store_malloc, store_free); png_set_write_fn(ps->pwrite, ps, store_write, store_flush); if (ppi != NULL) *ppi = ps->piwrite = png_create_info_struct(ps->pwrite); } Catch_anonymous return NULL; return ps->pwrite; } /* Cleanup when finished reading (either due to error or in the success case. ) */ static void store_read_reset(png_store *ps) { if (ps->pread != NULL) { anon_context(ps); Try png_destroy_read_struct(&ps->pread, &ps->piread, NULL); Catch_anonymous { /*error already output: continue*/ } ps->pread = NULL; ps->piread = NULL; } /* Always do this to be safe. */ store_pool_delete(ps, &ps->read_memory_pool); ps->current = NULL; ps->next = NULL; ps->readpos = 0; ps->validated = 0; } static void store_read_set(png_store *ps, png_uint_32 id) { png_store_file *pf = ps->saved; while (pf != NULL) { if (pf->id == id) { ps->current = pf; ps->next = NULL; store_read_buffer_next(ps); return; } pf = pf->next; } { size_t pos; char msg[FILE_NAME_SIZE+64]; pos = standard_name_from_id(msg, sizeof msg, 0, id); pos = safecat(msg, sizeof msg, pos, ": file not found"); png_error(ps->pread, msg); } } /* The main interface for reading a saved file - pass the id number of the file * to retrieve. Ids must be unique or the earlier file will be hidden. The API * returns a png_struct and, optionally, a png_info. Both of these will be * destroyed by store_read_reset above. */ static png_structp set_store_for_read(png_store *ps, png_infopp ppi, png_uint_32 id, PNG_CONST char *name) { /* Set the name for png_error */ safecat(ps->test, sizeof ps->test, 0, name); if (ps->pread != NULL) png_error(ps->pread, "read store already in use"); store_read_reset(ps); /* Both the create APIs can return NULL if used in their default mode * (because there is no other way of handling an error because the jmp_buf by * default is stored in png_struct and that has not been allocated!) * However, given that store_error works correctly in these circumstances we * don't ever expect NULL in this program. */ if (ps->speed) ps->pread = png_create_read_struct(PNG_LIBPNG_VER_STRING, ps, store_error, store_warning); else ps->pread = png_create_read_struct_2(PNG_LIBPNG_VER_STRING, ps, store_error, store_warning, &ps->read_memory_pool, store_malloc, store_free); if (ps->pread == NULL) { struct exception_context *the_exception_context = &ps->exception_context; store_log(ps, NULL, "png_create_read_struct returned NULL (unexpected)", 1/*error*/); Throw ps; } store_read_set(ps, id); if (ppi != NULL) *ppi = ps->piread = png_create_info_struct(ps->pread); return ps->pread; } /* The overall cleanup of a store simply calls the above then removes all the * saved files. This does not delete the store itself. */ static void store_delete(png_store *ps) { store_write_reset(ps); store_read_reset(ps); store_freefile(&ps->saved); if (ps->image != NULL) { free(ps->image-1); ps->image = NULL; ps->cb_image = 0; } } /*********************** PNG FILE MODIFICATION ON READ ************************/ /* Files may be modified on read. The following structure contains a complete * png_store together with extra members to handle modification and a special * read callback for libpng. To use this the 'modifications' field must be set * to a list of png_modification structures that actually perform the * modification, otherwise a png_modifier is functionally equivalent to a * png_store. There is a special read function, set_modifier_for_read, which * replaces set_store_for_read. */ typedef struct png_modifier { png_store this; /* I am a png_store */ struct png_modification *modifications; /* Changes to make */ enum modifier_state { modifier_start, /* Initial value */ modifier_signature, /* Have a signature */ modifier_IHDR /* Have an IHDR */ } state; /* My state */ /* Information from IHDR: */ png_byte bit_depth; /* From IHDR */ png_byte colour_type; /* From IHDR */ /* While handling PLTE, IDAT and IEND these chunks may be pended to allow * other chunks to be inserted. */ png_uint_32 pending_len; png_uint_32 pending_chunk; /* Test values */ double *gammas; unsigned int ngammas; /* Lowest sbit to test (libpng fails for sbit < 8) */ png_byte sbitlow; /* Error control - these are the limits on errors accepted by the gamma tests * below. */ double maxout8; /* Maximum output value error */ double maxabs8; /* Absolute sample error 0..1 */ double maxpc8; /* Percentage sample error 0..100% */ double maxout16; /* Maximum output value error */ double maxabs16; /* Absolute sample error 0..1 */ double maxpc16; /* Percentage sample error 0..100% */ /* Logged 8 and 16 bit errors ('output' values): */ double error_gray_2; double error_gray_4; double error_gray_8; double error_gray_16; double error_color_8; double error_color_16; /* Flags: */ /* Whether or not to interlace. */ int interlace_type :9; /* int, but must store '1' */ /* When to use the use_input_precision option: */ unsigned int use_input_precision :1; unsigned int use_input_precision_sbit :1; unsigned int use_input_precision_16to8 :1; unsigned int log :1; /* Log max error */ /* Buffer information, the buffer size limits the size of the chunks that can * be modified - they must fit (including header and CRC) into the buffer! */ size_t flush; /* Count of bytes to flush */ size_t buffer_count; /* Bytes in buffer */ size_t buffer_position; /* Position in buffer */ png_byte buffer[1024]; } png_modifier; static double abserr(png_modifier *pm, png_byte bit_depth) { return bit_depth == 16 ? pm->maxabs16 : pm->maxabs8; } static double pcerr(png_modifier *pm, png_byte bit_depth) { return (bit_depth == 16 ? pm->maxpc16 : pm->maxpc8) * .01; } static double outerr(png_modifier *pm, png_byte bit_depth) { /* There is a serious error in the 2 and 4 bit grayscale transform because * the gamma table value (8 bits) is simply shifted, not rouned, so the * error in 4 bit greyscale gamma is up to the value below. This is a hack * to allow pngvalid to succeed: */ if (bit_depth == 2) return .73182-.5; if (bit_depth == 4) return .90644-.5; if (bit_depth == 16) return pm->maxout16; return pm->maxout8; } /* This returns true if the test should be stopped now because it has already * failed and it is running silently. */ static int fail(png_modifier *pm) { return !pm->log && !pm->this.verbose && (pm->this.nerrors > 0 || (pm->this.treat_warnings_as_errors && pm->this.nwarnings > 0)); } static void modifier_init(png_modifier *pm) { memset(pm, 0, sizeof *pm); store_init(&pm->this); pm->modifications = NULL; pm->state = modifier_start; pm->sbitlow = 1U; pm->maxout8 = pm->maxpc8 = pm->maxabs8 = 0; pm->maxout16 = pm->maxpc16 = pm->maxabs16 = 0; pm->error_gray_2 = pm->error_gray_4 = pm->error_gray_8 = 0; pm->error_gray_16 = pm->error_color_8 = pm->error_color_16 = 0; pm->interlace_type = PNG_INTERLACE_NONE; pm->use_input_precision = 0; pm->use_input_precision_sbit = 0; pm->use_input_precision_16to8 = 0; pm->log = 0; /* Rely on the memset for all the other fields - there are no pointers */ } /* One modification structure must be provided for each chunk to be modified (in * fact more than one can be provided if multiple separate changes are desired * for a single chunk.) Modifications include adding a new chunk when a * suitable chunk does not exist. * * The caller of modify_fn will reset the CRC of the chunk and record 'modified' * or 'added' as appropriate if the modify_fn returns 1 (true). If the * modify_fn is NULL the chunk is simply removed. */ typedef struct png_modification { struct png_modification *next; png_uint_32 chunk; /* If the following is NULL all matching chunks will be removed: */ int (*modify_fn)(struct png_modifier *pm, struct png_modification *me, int add); /* If the following is set to PLTE, IDAT or IEND and the chunk has not been * found and modified (and there is a modify_fn) the modify_fn will be called * to add the chunk before the relevant chunk. */ png_uint_32 add; unsigned int modified :1; /* Chunk was modified */ unsigned int added :1; /* Chunk was added */ unsigned int removed :1; /* Chunk was removed */ } png_modification; static void modification_reset(png_modification *pmm) { if (pmm != NULL) { pmm->modified = 0; pmm->added = 0; pmm->removed = 0; modification_reset(pmm->next); } } static void modification_init(png_modification *pmm) { memset(pmm, 0, sizeof *pmm); pmm->next = NULL; pmm->chunk = 0; pmm->modify_fn = NULL; pmm->add = 0; modification_reset(pmm); } static void modifier_reset(png_modifier *pm) { store_read_reset(&pm->this); pm->modifications = NULL; pm->state = modifier_start; pm->bit_depth = pm->colour_type = 0; pm->pending_len = pm->pending_chunk = 0; pm->flush = pm->buffer_count = pm->buffer_position = 0; } /* Convenience macros. */ #define CHUNK(a,b,c,d) (((a)<<24)+((b)<<16)+((c)<<8)+(d)) #define CHUNK_IHDR CHUNK(73,72,68,82) #define CHUNK_PLTE CHUNK(80,76,84,69) #define CHUNK_IDAT CHUNK(73,68,65,84) #define CHUNK_IEND CHUNK(73,69,78,68) #define CHUNK_cHRM CHUNK(99,72,82,77) #define CHUNK_gAMA CHUNK(103,65,77,65) #define CHUNK_sBIT CHUNK(115,66,73,84) #define CHUNK_sRGB CHUNK(115,82,71,66) /* The guts of modification are performed during a read. */ static void modifier_crc(png_bytep buffer) { /* Recalculate the chunk CRC - a complete chunk must be in * the buffer, at the start. */ uInt datalen = png_get_uint_32(buffer); png_save_uint_32(buffer+datalen+8, crc32(0L, buffer+4, datalen+4)); } static void modifier_setbuffer(png_modifier *pm) { modifier_crc(pm->buffer); pm->buffer_count = png_get_uint_32(pm->buffer)+12; pm->buffer_position = 0; } /* Separate the callback into the actual implementation (which is passed the * png_modifier explicitly) and the callback, which gets the modifier from the * png_struct. */ static void modifier_read_imp(png_modifier *pm, png_bytep pb, png_size_t st) { while (st > 0) { size_t cb; png_uint_32 len, chunk; png_modification *mod; if (pm->buffer_position >= pm->buffer_count) switch (pm->state) { static png_byte sign[8] = { 137, 80, 78, 71, 13, 10, 26, 10 }; case modifier_start: store_read_imp(&pm->this, pm->buffer, 8); /* size of signature. */ pm->buffer_count = 8; pm->buffer_position = 0; if (memcmp(pm->buffer, sign, 8) != 0) png_error(pm->this.pread, "invalid PNG file signature"); pm->state = modifier_signature; break; case modifier_signature: store_read_imp(&pm->this, pm->buffer, 13+12); /* size of IHDR */ pm->buffer_count = 13+12; pm->buffer_position = 0; if (png_get_uint_32(pm->buffer) != 13 || png_get_uint_32(pm->buffer+4) != CHUNK_IHDR) png_error(pm->this.pread, "invalid IHDR"); /* Check the list of modifiers for modifications to the IHDR. */ mod = pm->modifications; while (mod != NULL) { if (mod->chunk == CHUNK_IHDR && mod->modify_fn && (*mod->modify_fn)(pm, mod, 0)) { mod->modified = 1; modifier_setbuffer(pm); } /* Ignore removal or add if IHDR! */ mod = mod->next; } /* Cache information from the IHDR (the modified one.) */ pm->bit_depth = pm->buffer[8+8]; pm->colour_type = pm->buffer[8+8+1]; pm->state = modifier_IHDR; pm->flush = 0; break; case modifier_IHDR: default: /* Read a new chunk and process it until we see PLTE, IDAT or * IEND. 'flush' indicates that there is still some data to * output from the preceding chunk. */ if ((cb = pm->flush) > 0) { if (cb > st) cb = st; pm->flush -= cb; store_read_imp(&pm->this, pb, cb); pb += cb; st -= cb; if (st <= 0) return; } /* No more bytes to flush, read a header, or handle a pending * chunk. */ if (pm->pending_chunk != 0) { png_save_uint_32(pm->buffer, pm->pending_len); png_save_uint_32(pm->buffer+4, pm->pending_chunk); pm->pending_len = 0; pm->pending_chunk = 0; } else store_read_imp(&pm->this, pm->buffer, 8); pm->buffer_count = 8; pm->buffer_position = 0; /* Check for something to modify or a terminator chunk. */ len = png_get_uint_32(pm->buffer); chunk = png_get_uint_32(pm->buffer+4); /* Terminators first, they may have to be delayed for added * chunks */ if (chunk == CHUNK_PLTE || chunk == CHUNK_IDAT || chunk == CHUNK_IEND) { mod = pm->modifications; while (mod != NULL) { if ((mod->add == chunk || (mod->add == CHUNK_PLTE && chunk == CHUNK_IDAT)) && mod->modify_fn != NULL && !mod->modified && !mod->added) { /* Regardless of what the modify function does do not run * this again. */ mod->added = 1; if ((*mod->modify_fn)(pm, mod, 1/*add*/)) { /* Reset the CRC on a new chunk */ if (pm->buffer_count > 0) modifier_setbuffer(pm); else { pm->buffer_position = 0; mod->removed = 1; } /* The buffer has been filled with something (we assume) * so output this. Pend the current chunk. */ pm->pending_len = len; pm->pending_chunk = chunk; break; /* out of while */ } } mod = mod->next; } /* Don't do any further processing if the buffer was modified - * otherwise the code will end up modifying a chunk that was just * added. */ if (mod != NULL) break; /* out of switch */ } /* If we get to here then this chunk may need to be modified. To do * this is must be less than 1024 bytes in total size, otherwise * it just gets flushed. */ if (len+12 <= sizeof pm->buffer) { store_read_imp(&pm->this, pm->buffer+pm->buffer_count, len+12-pm->buffer_count); pm->buffer_count = len+12; /* Check for a modification, else leave it be. */ mod = pm->modifications; while (mod != NULL) { if (mod->chunk == chunk) { if (mod->modify_fn == NULL) { /* Remove this chunk */ pm->buffer_count = pm->buffer_position = 0; mod->removed = 1; break; /* Terminate the while loop */ } else if ((*mod->modify_fn)(pm, mod, 0)) { mod->modified = 1; /* The chunk may have been removed: */ if (pm->buffer_count == 0) { pm->buffer_position = 0; break; } modifier_setbuffer(pm); } } mod = mod->next; } } else pm->flush = len+12 - pm->buffer_count; /* data + crc */ /* Take the data from the buffer (if there is any). */ break; } /* Here to read from the modifier buffer (not directly from * the store, as in the flush case above.) */ cb = pm->buffer_count - pm->buffer_position; if (cb > st) cb = st; memcpy(pb, pm->buffer + pm->buffer_position, cb); st -= cb; pb += cb; pm->buffer_position += cb; } } /* The callback: */ static void modifier_read(png_structp pp, png_bytep pb, png_size_t st) { png_modifier *pm = png_get_io_ptr(pp); if (pm == NULL || pm->this.pread != pp) png_error(pp, "bad modifier_read call"); modifier_read_imp(pm, pb, st); } /* Like store_progressive_read but the data is getting changed as we go so we * need a local buffer. */ static void modifier_progressive_read(png_modifier *pm, png_structp pp, png_infop pi) { if (pm->this.pread != pp || pm->this.current == NULL || pm->this.next == NULL) png_error(pp, "store state damaged (progressive)"); /* This is another Horowitz and Hill random noise generator. In this case * the aim is to stress the progressive reader with truely horrible variable * buffer sizes in the range 1..500, so a sequence of 9 bit random numbers is * generated. We could probably just count from 1 to 32767 and get as good * a result. */ for (;;) { static png_uint_32 noise = 1; png_size_t cb, cbAvail; png_byte buffer[512]; /* Generate 15 more bits of stuff: */ noise = (noise << 9) | ((noise ^ (noise >> (9-5))) & 0x1ff); cb = noise & 0x1ff; /* Check that this number of bytes are available (in the current buffer.) * (This doesn't quite work - the modifier might delete a chunk; unlikely * but possible, it doesn't happen at present because the modifier only * adds chunks to standard images.) */ cbAvail = store_read_buffer_avail(&pm->this); if (pm->buffer_count > pm->buffer_position) cbAvail += pm->buffer_count - pm->buffer_position; if (cb > cbAvail) { /* Check for EOF: */ if (cbAvail == 0) break; cb = cbAvail; } modifier_read_imp(pm, buffer, cb); png_process_data(pp, pi, buffer, cb); } /* Check the invariants at the end (if this fails it's a problem in this * file!) */ if (pm->buffer_count > pm->buffer_position || pm->this.next != &pm->this.current->data || pm->this.readpos < pm->this.current->datacount) png_error(pp, "progressive read implementation error"); } /* Set up a modifier. */ static png_structp set_modifier_for_read(png_modifier *pm, png_infopp ppi, png_uint_32 id, PNG_CONST char *name) { /* Do this first so that the modifier fields are cleared even if an error * happens allocating the png_struct. No allocation is done here so no * cleanup is required. */ pm->state = modifier_start; pm->bit_depth = 0; pm->colour_type = 255; pm->pending_len = 0; pm->pending_chunk = 0; pm->flush = 0; pm->buffer_count = 0; pm->buffer_position = 0; return set_store_for_read(&pm->this, ppi, id, name); } /***************************** STANDARD PNG FILES *****************************/ /* Standard files - write and save standard files. */ /* The standard files are constructed with rows which fit into a 1024 byte row * buffer. This makes allocation easier below. Further regardless of the file * format every file has 128 pixels (giving 1024 bytes for 64bpp formats). * * Files are stored with no gAMA or sBIT chunks, with a PLTE only when needed * and with an ID derived from the colour type, bit depth and interlace type * as above (FILEID). */ /* The number of passes is related to the interlace type, there's no libpng API * to determine this so we need an inquiry function: */ static int npasses_from_interlace_type(png_structp pp, int interlace_type) { switch (interlace_type) { default: png_error(pp, "invalid interlace type"); case PNG_INTERLACE_NONE: return 1; case PNG_INTERLACE_ADAM7: return 7; } } #define STD_WIDTH 128U #define STD_ROWMAX (STD_WIDTH*8U) static unsigned int bit_size(png_structp pp, png_byte colour_type, png_byte bit_depth) { switch (colour_type) { case 0: return bit_depth; case 2: return 3*bit_depth; case 3: return bit_depth; case 4: return 2*bit_depth; case 6: return 4*bit_depth; default: png_error(pp, "invalid color type"); } } static size_t standard_rowsize(png_structp pp, png_byte colour_type, png_byte bit_depth) { return (STD_WIDTH * bit_size(pp, colour_type, bit_depth)) / 8; } /* standard_wdith(pp, colour_type, bit_depth) current returns the same number * every time, so just use a macro: */ #define standard_width(pp, colour_type, bit_depth) STD_WIDTH static png_uint_32 standard_height(png_structp pp, png_byte colour_type, png_byte bit_depth) { switch (bit_size(pp, colour_type, bit_depth)) { case 1: case 2: case 4: return 1; /* Total of 128 pixels */ case 8: return 2; /* Total of 256 pixels/bytes */ case 16: return 512; /* Total of 65536 pixels */ case 24: case 32: return 512; /* 65536 pixels */ case 48: case 64: return 2048;/* 4 x 65536 pixels. */ default: return 0; /* Error, will be caught later */ } } /* So the maximum standard image size is: */ #define STD_IMAGEMAX (STD_ROWMAX * 2048) static void standard_row(png_structp pp, png_byte buffer[STD_ROWMAX], png_byte colour_type, png_byte bit_depth, png_uint_32 y) { png_uint_32 v = y << 7; png_uint_32 i = 0; switch (bit_size(pp, colour_type, bit_depth)) { case 1: while (i<128/8) buffer[i] = v & 0xff, v += 17, ++i; return; case 2: while (i<128/4) buffer[i] = v & 0xff, v += 33, ++i; return; case 4: while (i<128/2) buffer[i] = v & 0xff, v += 65, ++i; return; case 8: /* 256 bytes total, 128 bytes in each row set as follows: */ while (i<128) buffer[i] = v & 0xff, ++v, ++i; return; case 16: /* Generate all 65536 pixel values in order, this includes the 8 bit GA * case as we as the 16 bit G case. */ while (i<128) buffer[2*i] = (v>>8) & 0xff, buffer[2*i+1] = v & 0xff, ++v, ++i; return; case 24: /* 65535 pixels, but rotate the values. */ while (i<128) { /* Three bytes per pixel, r, g, b, make b by r^g */ buffer[3*i+0] = (v >> 8) & 0xff; buffer[3*i+1] = v & 0xff; buffer[3*i+2] = ((v >> 8) ^ v) & 0xff; ++v; ++i; } return; case 32: /* 65535 pixels, r, g, b, a; just replicate */ while (i<128) { buffer[4*i+0] = (v >> 8) & 0xff; buffer[4*i+1] = v & 0xff; buffer[4*i+2] = (v >> 8) & 0xff; buffer[4*i+3] = v & 0xff; ++v; ++i; } return; case 48: /* y is maximum 2047, giving 4x65536 pixels, make 'r' increase by 1 at * each pixel, g increase by 257 (0x101) and 'b' by 0x1111: */ while (i<128) { png_uint_32 t = v++; buffer[6*i+0] = (t >> 8) & 0xff; buffer[6*i+1] = t & 0xff; t *= 257; buffer[6*i+2] = (t >> 8) & 0xff; buffer[6*i+3] = t & 0xff; t *= 17; buffer[6*i+4] = (t >> 8) & 0xff; buffer[6*i+5] = t & 0xff; ++i; } return; case 64: /* As above in the 32 bit case. */ while (i<128) { png_uint_32 t = v++; buffer[8*i+0] = (t >> 8) & 0xff; buffer[8*i+1] = t & 0xff; buffer[8*i+4] = (t >> 8) & 0xff; buffer[8*i+5] = t & 0xff; t *= 257; buffer[8*i+2] = (t >> 8) & 0xff; buffer[8*i+3] = t & 0xff; buffer[8*i+6] = (t >> 8) & 0xff; buffer[8*i+7] = t & 0xff; ++i; } return; default: break; } png_error(pp, "internal error"); } /* This is just to do the right cast - could be changed to a function to check * 'bd' but there isn't much point. */ #define DEPTH(bd) ((png_byte)(1U << (bd))) static void make_standard_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type, png_byte PNG_CONST bit_depth, int interlace_type, png_const_charp name) { context(ps, fault); Try { png_infop pi; png_structp pp = set_store_for_write(ps, &pi, name); png_uint_32 h; /* In the event of a problem return control to the Catch statement below * to do the clean up - it is not possible to 'return' directly from a Try * block. */ if (pp == NULL) Throw ps; h = standard_height(pp, colour_type, bit_depth); png_set_IHDR(pp, pi, standard_width(pp, colour_type, bit_depth), h, bit_depth, colour_type, interlace_type, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE); if (colour_type == 3) /* palette */ { unsigned int i = 0; png_color pal[256]; do pal[i].red = pal[i].green = pal[i].blue = (png_byte)i; while(++i < 256U); png_set_PLTE(pp, pi, pal, 256); } png_write_info(pp, pi); if (png_get_rowbytes(pp, pi) != standard_rowsize(pp, colour_type, bit_depth)) png_error(pp, "row size incorrect"); else { /* Somewhat confusingly this must be called *after* png_write_info * because, if it is called before, the information in *pp has not been * updated to reflect the interlaced image. */ int npasses = png_set_interlace_handling(pp); int pass; if (npasses != npasses_from_interlace_type(pp, interlace_type)) png_error(pp, "write: png_set_interlace_handling failed"); for (pass=1; pass<=npasses; ++pass) { png_uint_32 y; for (y=0; ytest, sizeof ps->test, 0, "make standard images"); /* Arguments are colour_type, low bit depth, high bit depth */ make_standard(ps, 0, 0, WRITE_BDHI); make_standard(ps, 2, 3, WRITE_BDHI); make_standard(ps, 3, 0, 3/*palette: max 8 bits*/); make_standard(ps, 4, 3, WRITE_BDHI); make_standard(ps, 6, 3, WRITE_BDHI); } /* Tests - individual test cases */ /* Like 'make_standard' but errors are deliberately introduced into the calls * to ensure that they get detected - it should not be possible to write an * invalid image with libpng! */ static void sBIT0_error_fn(png_structp pp, png_infop pi) { /* 0 is invalid... */ png_color_8 bad; bad.red = bad.green = bad.blue = bad.gray = bad.alpha = 0; png_set_sBIT(pp, pi, &bad); } static void sBIT_error_fn(png_structp pp, png_infop pi) { png_byte bit_depth; png_color_8 bad; if (png_get_color_type(pp, pi) == PNG_COLOR_TYPE_PALETTE) bit_depth = 8; else bit_depth = png_get_bit_depth(pp, pi); /* Now we know the bit depth we can easily generate an invalid sBIT entry */ bad.red = bad.green = bad.blue = bad.gray = bad.alpha = (png_byte)(bit_depth+1); png_set_sBIT(pp, pi, &bad); } static PNG_CONST struct { void (*fn)(png_structp, png_infop); PNG_CONST char *msg; unsigned int warning :1; /* the error is a warning... */ } error_test[] = { { sBIT0_error_fn, "sBIT(0): failed to detect error", 1 }, { sBIT_error_fn, "sBIT(too big): failed to detect error", 1 }, }; static void make_error(png_store* ps, png_byte PNG_CONST colour_type, png_byte bit_depth, int interlace_type, int test, png_const_charp name) { context(ps, fault); Try { png_structp pp; png_infop pi; pp = set_store_for_write(ps, &pi, name); if (pp == NULL) Throw ps; png_set_IHDR(pp, pi, standard_width(pp, colour_type, bit_depth), standard_height(pp, colour_type, bit_depth), bit_depth, colour_type, interlace_type, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE); if (colour_type == 3) /* palette */ { unsigned int i = 0; png_color pal[256]; do pal[i].red = pal[i].green = pal[i].blue = (png_byte)i; while(++i < 256U); png_set_PLTE(pp, pi, pal, 256); } /* Time for a few errors, these are in various optional chunks, the * standard tests test the standard chunks pretty well. */ Try { /* Expect this to throw: */ ps->expect_error = !error_test[test].warning; ps->expect_warning = error_test[test].warning; ps->saw_warning = 0; error_test[test].fn(pp, pi); /* Normally the error is only detected here: */ png_write_info(pp, pi); /* And handle the case where it was only a warning: */ if (ps->expect_warning && ps->saw_warning) Throw ps; /* If we get here there is a problem, we have success - no error or * no warning - when we shouldn't have success. Log an error. */ store_log(ps, pp, error_test[test].msg, 1/*error*/); } Catch (fault) ps = fault; /* expected exit, make sure ps is not clobbered */ /* And clear these flags */ ps->expect_error = 0; ps->expect_warning = 0; /* Now write the whole image, just to make sure that the detected, or * undetected, errro has not created problems inside libpng. */ if (png_get_rowbytes(pp, pi) != standard_rowsize(pp, colour_type, bit_depth)) png_error(pp, "row size incorrect"); else { png_uint_32 h = standard_height(pp, colour_type, bit_depth); int npasses = png_set_interlace_handling(pp); int pass; if (npasses != npasses_from_interlace_type(pp, interlace_type)) png_error(pp, "write: png_set_interlace_handling failed"); for (pass=1; pass<=npasses; ++pass) { png_uint_32 y; for (y=0; ythis, colour_type, DEPTH(bdlo), interlace_type, test, name); if (fail(pm)) return 0; } } } return 1; /* keep going */ } static void perform_error_test(png_modifier *pm) { /* Need to do this here because we just write in this test. */ safecat(pm->this.test, sizeof pm->this.test, 0, "error test"); if (!make_errors(pm, 0, 0, WRITE_BDHI)) return; if (!make_errors(pm, 2, 3, WRITE_BDHI)) return; if (!make_errors(pm, 3, 0, 3)) return; if (!make_errors(pm, 4, 3, WRITE_BDHI)) return; if (!make_errors(pm, 6, 3, WRITE_BDHI)) return; } /* Because we want to use the same code in both the progressive reader and the * sequential reader it is necessary to deal with the fact that the progressive * reader callbacks only have one parameter (png_get_progressive_ptr()), so this * must contain all the test parameters and all the local variables directly * accessible to the sequential reader implementation. * * The techinque adopted is to reinvent part of what Dijkstra termed a * 'display'; an array of pointers to the stack frames of enclosing functions so * that a nested function definition can access the local (C auto) variables of * the functions that contain its definition. In fact C provides the first * pointer (the local variables - the stack frame pointer) and the last (the * global variables - the BCPL global vector typically implemented as global * addresses), this code requires one more pointer to make the display - the * local variables (and function call parameters) of the function that actually * invokes either the progressive or sequential reader. * * Perhaps confusingly this technique is confounded with classes - the * 'standard_display' defined here is sub-classed as the 'gamma_display' below. * A gamma_display is a standard_display, taking advantage of the ANSI-C * requirement that the pointer to the first member of a structure must be the * same as the pointer to the structure. This allows us to reuse standard_ * functions in the gamma test code; something that could not be done with * nested funtions! */ typedef struct standard_display { png_store* ps; /* Test parameters (passed to the function) */ png_byte colour_type; png_byte bit_depth; int interlace_type; png_uint_32 id; /* Calculated file ID */ png_uint_32 w; /* Width of image */ png_uint_32 h; /* Height of image */ int npasses; /* Number of interlaced passes */ size_t cbRow; /* Bytes in a row of the output image. */ } standard_display; static void standard_display_init(standard_display *dp, png_store* ps, png_byte colour_type, png_byte bit_depth, int interlace_type) { dp->ps = ps; dp->colour_type = colour_type; dp->bit_depth = bit_depth; dp->interlace_type = interlace_type; dp->id = FILEID(colour_type, bit_depth, interlace_type); dp->w = 0; dp->h = 0; dp->npasses = 0; dp->cbRow = 0; } /* By passing a 'standard_display' the progressive callbacks can be used * directly by the sequential code, the functions suffixed _imp are the * implementations, the functions without the suffix are the callbacks. * * The code for the info callback is split into two because this callback calls * png_read_update_info or png_start_read_image and what gets called depends on * whether the info needs updating (we want to test both calls in pngvalid.) */ static void standard_info_part1(standard_display *dp, png_structp pp, png_infop pi) { if (png_get_bit_depth(pp, pi) != dp->bit_depth) png_error(pp, "validate: bit depth changed"); if (png_get_color_type(pp, pi) != dp->colour_type) png_error(pp, "validate: color type changed"); if (png_get_filter_type(pp, pi) != PNG_FILTER_TYPE_BASE) png_error(pp, "validate: filter type changed"); if (png_get_interlace_type(pp, pi) != dp->interlace_type) png_error(pp, "validate: interlacing changed"); if (png_get_compression_type(pp, pi) != PNG_COMPRESSION_TYPE_BASE) png_error(pp, "validate: compression type changed"); dp->w = png_get_image_width(pp, pi); if (dp->w != standard_width(pp, dp->colour_type, dp->bit_depth)) png_error(pp, "validate: image width changed"); dp->h = png_get_image_height(pp, pi); if (dp->h != standard_height(pp, dp->colour_type, dp->bit_depth)) png_error(pp, "validate: image height changed"); /* Important: this is validating the value *before* any transforms have been * put in place. It doesn't matter for the standard tests, where there are * no transforms, it does for other tests where rowbytes may change after * png_read_update_info. */ if (png_get_rowbytes(pp, pi) != standard_rowsize(pp, dp->colour_type, dp->bit_depth)) png_error(pp, "validate: row size changed"); if (dp->colour_type == 3) /* palette */ { png_colorp pal; int num; /* This could be passed in but isn't - the values set above when the * standard images were made are just repeated here. */ if (png_get_PLTE(pp, pi, &pal, &num) & PNG_INFO_PLTE) { int i; if (num != 256) png_error(pp, "validate: color type 3 PLTE chunk size changed"); for (i=0; inpasses = png_set_interlace_handling(pp); if (dp->npasses != npasses_from_interlace_type(pp, dp->interlace_type)) png_error(pp, "validate: file changed interlace type"); /* Caller calls png_read_update_info or png_start_read_image now, then calls * part2. */ } /* This must be called *after* the png_read_update_info call to get the correct * 'rowbytes' value, otherwise png_get_rowbytes will refer to the untransformed * image. */ static void standard_info_part2(standard_display *dp, png_structp pp, png_infop pi, int nImages) { /* Record cbRow now that it can be found. */ dp->cbRow = png_get_rowbytes(pp, pi); /* Then ensure there is enough space for the output image(s). */ store_ensure_image(dp->ps, pp, nImages * dp->cbRow * dp->h); } static void standard_info_imp(standard_display *dp, png_structp pp, png_infop pi, int nImages) { /* Note that the validation routine has the side effect of turning on * interlace handling in the subsequent code. */ standard_info_part1(dp, pp, pi); /* And the info callback has to call this (or png_read_update_info - see * below in the png_modifier code for that variant. */ png_start_read_image(pp); /* Validate the height, width and rowbytes plus ensure that sufficient buffer * exists for decoding the image. */ standard_info_part2(dp, pp, pi, nImages); } static void standard_info(png_structp pp, png_infop pi) { standard_display *dp = png_get_progressive_ptr(pp); /* Call with nImages==1 because the progressive reader can only produce one * image. */ standard_info_imp(dp, pp, pi, 1/*only one image*/); } static void progressive_row(png_structp pp, png_bytep new_row, png_uint_32 y, int pass) { UNUSED(pass); /* When handling interlacing some rows will be absent in each pass, the * callback still gets called, but with a NULL pointer. We need our own * 'cbRow', but we can't call png_get_rowbytes because we got no info * structure. */ if (new_row != NULL) { PNG_CONST standard_display *dp = png_get_progressive_ptr(pp); /* Combine the new row into the old: */ png_progressive_combine_row(pp, dp->ps->image + y * dp->cbRow, new_row); } } static void sequential_row(standard_display *dp, png_structp pp, png_infop pi, PNG_CONST png_bytep pImage, PNG_CONST png_bytep pDisplay) { PNG_CONST int npasses = dp->npasses; PNG_CONST png_uint_32 h = dp->h; PNG_CONST size_t cbRow = dp->cbRow; int pass; for (pass=1; pass <= npasses; ++pass) { png_uint_32 y; png_bytep pRow1 = pImage; png_bytep pRow2 = pDisplay; for (y=0; ycolour_type, dp->bit_depth, y); /* At the end both the 'read' and 'display' arrays should end up identical. * In earlier passes 'read' will be narrow, containing only the columns that * were read, and display will be full width but populated with garbage where * pixels have not been filled in. */ if (row != NULL && memcmp(std, row, dp->cbRow) != 0) { char msg[64]; sprintf(msg, "PNG image row %d changed", y); png_error(pp, msg); } if (display != NULL && memcmp(std, display, dp->cbRow) != 0) { char msg[64]; sprintf(msg, "display row %d changed", y); png_error(pp, msg); } } static void standard_image_validate(standard_display *dp, png_structp pp, png_const_bytep pImage, png_const_bytep pDisplay) { png_uint_32 y; for (y=0; yh; ++y) { standard_row_validate(dp, pp, pImage, pDisplay, y); if (pImage != NULL) pImage += dp->cbRow; if (pDisplay != NULL) pDisplay += dp->cbRow; } /* This avoids false positives if the validation code is never called! */ dp->ps->validated = 1; } static void standard_end(png_structp pp, png_infop pi) { standard_display *dp = png_get_progressive_ptr(pp); UNUSED(pi); /* Validate the image - progressive reading only produces one variant for * interlaced images. */ standard_image_validate(dp, pp, dp->ps->image, NULL); } /* A single test run checking the standard image to ensure it is not damaged. */ static void standard_test(png_store* PNG_CONST psIn, png_byte PNG_CONST colour_typeIn, png_byte PNG_CONST bit_depthIn, int interlace_typeIn) { standard_display d; context(psIn, fault); /* Set up the display (stack frame) variables from the arguments to the * function and initialize the locals that are filled in later. */ standard_display_init(&d, psIn, colour_typeIn, bit_depthIn, interlace_typeIn); /* Everything is protected by a Try/Catch. The functions called also * typically have local Try/Catch blocks. */ Try { png_structp pp; png_infop pi; /* Get a png_struct for writing the image, this will throw an error if it * fails, so we don't need to check the result. */ pp = set_store_for_read(d.ps, &pi, d.id, d.ps->progressive ? "progressive reader" : "sequential reader"); /* Introduce the correct read function. */ if (d.ps->progressive) { png_set_progressive_read_fn(pp, &d, standard_info, progressive_row, standard_end); /* Now feed data into the reader until we reach the end: */ store_progressive_read(d.ps, pp, pi); } else { /* Note that this takes the store, not the display. */ png_set_read_fn(pp, d.ps, store_read); /* Check the header values: */ png_read_info(pp, pi); /* The code tests both versions of the images that the sequential * reader can produce. */ standard_info_imp(&d, pp, pi, 2/*images*/); /* Need the total bytes in the image below; we can't get to this point * unless the PNG file values have been checked against the expected * values. */ { PNG_CONST png_bytep pImage = d.ps->image; PNG_CONST png_bytep pDisplay = pImage + d.cbRow * d.h; sequential_row(&d, pp, pi, pImage, pDisplay); /* After the last pass loop over the rows again to check that the * image is correct. */ standard_image_validate(&d, pp, pImage, pDisplay); } } /* Check for validation. */ if (!d.ps->validated) png_error(pp, "image read failed silently"); /* Successful completion. */ } Catch(fault) d.ps = fault; /* make sure this hasn't been clobbered. */ /* In either case clean up the store. */ store_read_reset(d.ps); } static int test_standard(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type, int bdlo, int PNG_CONST bdhi) { for (; bdlo <= bdhi; ++bdlo) { int interlace_type; for (interlace_type = PNG_INTERLACE_NONE; interlace_type < PNG_INTERLACE_LAST; ++interlace_type) { /* Test both sequential and standard readers here. */ pm->this.progressive = !pm->this.progressive; standard_test(&pm->this, colour_type, DEPTH(bdlo), interlace_type); if (fail(pm)) return 0; pm->this.progressive = !pm->this.progressive; standard_test(&pm->this, colour_type, DEPTH(bdlo), interlace_type); if (fail(pm)) return 0; } } return 1; /*keep going*/ } static void perform_standard_test(png_modifier *pm) { /* Test each colour type over the valid range of bit depths (expressed as * log2(bit_depth) in turn, stop as soon as any error is detected. */ if (!test_standard(pm, 0, 0, READ_BDHI)) return; if (!test_standard(pm, 2, 3, READ_BDHI)) return; if (!test_standard(pm, 3, 0, 3)) return; if (!test_standard(pm, 4, 3, READ_BDHI)) return; if (!test_standard(pm, 6, 3, READ_BDHI)) return; } /********************************* GAMMA TESTS ********************************/ /* Gamma test images. */ typedef struct gamma_modification { png_modification this; png_fixed_point gamma; } gamma_modification; static int gamma_modify(png_modifier *pm, png_modification *me, int add) { UNUSED(add); /* This simply dumps the given gamma value into the buffer. */ png_save_uint_32(pm->buffer, 4); png_save_uint_32(pm->buffer+4, CHUNK_gAMA); png_save_uint_32(pm->buffer+8, ((gamma_modification*)me)->gamma); return 1; } static void gamma_modification_init(gamma_modification *me, png_modifier *pm, double gamma) { double g; modification_init(&me->this); me->this.chunk = CHUNK_gAMA; me->this.modify_fn = gamma_modify; me->this.add = CHUNK_PLTE; g = floor(gamma * 100000 + .5); me->gamma = (png_fixed_point)g; me->this.next = pm->modifications; pm->modifications = &me->this; } typedef struct srgb_modification { png_modification this; png_byte intent; } srgb_modification; static int srgb_modify(png_modifier *pm, png_modification *me, int add) { UNUSED(add); /* As above, ignore add and just make a new chunk */ png_save_uint_32(pm->buffer, 1); png_save_uint_32(pm->buffer+4, CHUNK_sRGB); pm->buffer[8] = ((srgb_modification*)me)->intent; return 1; } static void srgb_modification_init(srgb_modification *me, png_modifier *pm, png_byte intent) { modification_init(&me->this); me->this.chunk = CHUNK_sBIT; if (intent <= 3) /* if valid, else *delete* sRGB chunks */ { me->this.modify_fn = srgb_modify; me->this.add = CHUNK_PLTE; me->intent = intent; } else { me->this.modify_fn = 0; me->this.add = 0; me->intent = 0; } me->this.next = pm->modifications; pm->modifications = &me->this; } typedef struct sbit_modification { png_modification this; png_byte sbit; } sbit_modification; static int sbit_modify(png_modifier *pm, png_modification *me, int add) { png_byte sbit = ((sbit_modification*)me)->sbit; if (pm->bit_depth > sbit) { int cb = 0; switch (pm->colour_type) { case 0: cb = 1; break; case 2: case 3: cb = 3; break; case 4: cb = 2; break; case 6: cb = 4; break; default: png_error(pm->this.pread, "unexpected colour type in sBIT modification"); } png_save_uint_32(pm->buffer, cb); png_save_uint_32(pm->buffer+4, CHUNK_sBIT); while (cb > 0) (pm->buffer+8)[--cb] = sbit; return 1; } else if (!add) { /* Remove the sBIT chunk */ pm->buffer_count = pm->buffer_position = 0; return 1; } else return 0; /* do nothing */ } static void sbit_modification_init(sbit_modification *me, png_modifier *pm, png_byte sbit) { modification_init(&me->this); me->this.chunk = CHUNK_sBIT; me->this.modify_fn = sbit_modify; me->this.add = CHUNK_PLTE; me->sbit = sbit; me->this.next = pm->modifications; pm->modifications = &me->this; } /* Reader callbacks and implementations, where they differ from the standard * ones. */ typedef struct gamma_display { standard_display this; /* Parameters */ png_modifier* pm; double file_gamma; double screen_gamma; png_byte sbit; int threshold_test; PNG_CONST char* name; int speed; int use_input_precision; int strip16; /* Local variables */ double maxerrout; double maxerrpc; double maxerrabs; } gamma_display; static void gamma_display_init(gamma_display *dp, png_modifier *pm, png_byte colour_type, png_byte bit_depth, int interlace_type, double file_gamma, double screen_gamma, png_byte sbit, int threshold_test, int speed, int use_input_precision, int strip16) { /* Standard fields */ standard_display_init(&dp->this, &pm->this, colour_type, bit_depth, interlace_type); /* Parameter fields */ dp->pm = pm; dp->file_gamma = file_gamma; dp->screen_gamma = screen_gamma; dp->sbit = sbit; dp->threshold_test = threshold_test; dp->speed = speed; dp->use_input_precision = use_input_precision; dp->strip16 = strip16; /* Local variable fields */ dp->maxerrout = dp->maxerrpc = dp->maxerrabs = 0; } static void gamma_info_imp(gamma_display *dp, png_structp pp, png_infop pi) { /* Reuse the standard stuff as appropriate. */ standard_info_part1(&dp->this, pp, pi); /* If requested strip 16 to 8 bits - this is handled automagically below * because the output bit depth is read from the library. Note that there * are interactions with sBIT but, internally, libpng makes sbit at most * PNG_MAX_GAMMA_8 when doing the following. */ if (dp->strip16) png_set_strip_16(pp); png_read_update_info(pp, pi); /* Now we may get a different cbRow: */ standard_info_part2(&dp->this, pp, pi, 1/*images*/); } static void gamma_info(png_structp pp, png_infop pi) { gamma_info_imp(png_get_progressive_ptr(pp), pp, pi); } static void gamma_image_validate(gamma_display *dp, png_structp pp, png_infop pi, png_const_bytep pRow) { /* Get some constants derived from the input and output file formats: */ PNG_CONST png_byte sbit = dp->sbit; PNG_CONST double file_gamma = dp->file_gamma; PNG_CONST double screen_gamma = dp->screen_gamma; PNG_CONST int use_input_precision = dp->use_input_precision; PNG_CONST int speed = dp->speed; PNG_CONST png_byte in_ct = dp->this.colour_type; PNG_CONST png_byte in_bd = dp->this.bit_depth; PNG_CONST png_uint_32 w = dp->this.w; PNG_CONST png_uint_32 h = dp->this.h; PNG_CONST size_t cbRow = dp->this.cbRow; PNG_CONST png_byte out_ct = png_get_color_type(pp, pi); PNG_CONST png_byte out_bd = png_get_bit_depth(pp, pi); PNG_CONST unsigned int outmax = (1U<pm, out_bd); PNG_CONST double maxout = outerr(dp->pm, out_bd); PNG_CONST double maxpc = pcerr(dp->pm, out_bd); /* There are three sources of error, firstly the quantization in the * file encoding, determined by sbit and/or the file depth, secondly * the output (screen) gamma and thirdly the output file encoding. * Since this API receives the screen and file gamma in double * precision it is possible to calculate an exact answer given an input * pixel value. Therefore we assume that the *input* value is exact - * sample/maxsample - calculate the corresponding gamma corrected * output to the limits of double precision arithmetic and compare with * what libpng returns. * * Since the library must quantise the output to 8 or 16 bits there is * a fundamental limit on the accuracy of the output of +/-.5 - this * quantisation limit is included in addition to the other limits * specified by the paramaters to the API. (Effectively, add .5 * everywhere.) * * The behavior of the 'sbit' paramter is defined by section 12.5 * (sample depth scaling) of the PNG spec. That section forces the * decoder to assume that the PNG values have been scaled if sBIT is * presence: * * png-sample = floor( input-sample * (max-out/max-in) + .5 ); * * This means that only a subset of the possible PNG values should * appear in the input, however the spec allows the encoder to use a * variety of approximations to the above and doesn't require any * restriction of the values produced. * * Nevertheless the spec requires that the upper 'sBIT' bits of the * value stored in a PNG file be the original sample bits. * Consequently the code below simply scales the top sbit bits by * (1<= PNG_GAMMA_THRESHOLD && !dp->threshold_test && !speed && in_ct != 3) || in_bd != out_bd; PNG_CONST unsigned int samples_per_pixel = (out_ct & 2U) ? 3U : 1U; PNG_CONST double gamma = 1/(file_gamma*screen_gamma); /* Overall */ double maxerrout = 0, maxerrabs = 0, maxerrpc = 0; png_uint_32 y; for (y=0; y> (in_bd-sbit); double i, sample, encoded_sample, output, encoded_error, error; double es_lo, es_hi; /* First check on the 'perfect' result obtained from the * digitized input value, id, and compare this against the * actual digitized result, 'od'. 'i' is the input result * in the range 0..1: * * NOTE: sBIT should be taken into account here but isn't, * as described above. */ i = isbit; i /= (1U< maxerrout) maxerrout = encoded_error; if (encoded_error < .5+maxout) continue; /* There may be an error, calculate the actual sample * values - unencoded light intensity values. Note that * in practice these are not unencoded because they * include a 'viewing correction' to decrease or * (normally) increase the perceptual contrast of the * image. There's nothing we can do about this - we don't * know what it is - so assume the unencoded value is * perceptually linear. */ sample = pow(i, 1/file_gamma); /* In range 0..1 */ output = od; output /= outmax; output = pow(output, screen_gamma); /* Now we have the numbers for real errors, both absolute * values as as a percentage of the correct value (output): */ error = fabs(sample-output); if (error > maxerrabs) maxerrabs = error; /* The following is an attempt to ignore the tendency of * quantization to dominate the percentage errors for low * output sample values: */ if (sample*maxpc > .5+maxabs) { double pcerr = error/sample; if (pcerr > maxerrpc) maxerrpc = pcerr; } /* Now calculate the digitization limits for * 'encoded_sample' using the 'max' values. Note that * maxout is in the encoded space but maxpc and maxabs are * in linear light space. * * First find the maximum error in linear light space, * range 0..1: */ { double tmp = sample * maxpc; if (tmp < maxabs) tmp = maxabs; /* Low bound - the minimum of the three: */ es_lo = encoded_sample - maxout; if (es_lo > 0 && sample-tmp > 0) { double l = outmax * pow(sample-tmp, 1/screen_gamma); if (l < es_lo) es_lo = l; } else es_lo = 0; es_hi = encoded_sample + maxout; if (es_hi < outmax && sample+tmp < 1) { double h = outmax * pow(sample+tmp, 1/screen_gamma); if (h > es_hi) es_hi = h; } else es_hi = outmax; } /* The primary test is that the final encoded value * returned by the library should be between the two limits * (inclusive) that were calculated above. At this point * quantization of the output must be taken into account. */ if (od+.5 < es_lo || od-.5 > es_hi) { /* There has been an error in processing. */ double is_lo, is_hi; if (use_input_precision) { /* Ok, something is wrong - this actually happens in * current libpng sbit processing. Assume that the * input value (id, adjusted for sbit) can be * anywhere between value-.5 and value+.5 - quite a * large range if sbit is low. */ double tmp = (isbit - .5)/((1U< 0) { is_lo = outmax * pow(tmp, gamma) - maxout; if (is_lo < 0) is_lo = 0; } else is_lo = 0; tmp = (isbit + .5)/((1U< outmax) is_hi = outmax; } else is_hi = outmax; if (!(od+.5 < is_lo || od-.5 > is_hi)) continue; } else is_lo = es_lo, is_hi = es_hi; { char msg[256]; sprintf(msg, "error: %.3f; %u{%u;%u} -> %u not %.2f (%.1f-%.1f)", od-encoded_sample, id, sbit, isbit, od, encoded_sample, is_lo, is_hi); png_warning(pp, msg); } } } } else if (!speed && memcmp(std, pRow, cbRow) != 0) { char msg[64]; /* No transform is expected on the threshold tests. */ sprintf(msg, "gamma: below threshold row %d changed", y); png_error(pp, msg); } } /* row (y) loop */ dp->maxerrout = maxerrout; dp->maxerrabs = maxerrabs; dp->maxerrpc = maxerrpc; dp->this.ps->validated = 1; } static void gamma_end(png_structp pp, png_infop pi) { gamma_display *dp = png_get_progressive_ptr(pp); gamma_image_validate(dp, pp, pi, dp->this.ps->image); } /* A single test run checking a gamma transformation. * * maxabs: maximum absolute error as a fraction * maxout: maximum output error in the output units * maxpc: maximum percentage error (as a percentage) */ static void gamma_test(png_modifier *pmIn, PNG_CONST png_byte colour_typeIn, PNG_CONST png_byte bit_depthIn, PNG_CONST int interlace_typeIn, PNG_CONST double file_gammaIn, PNG_CONST double screen_gammaIn, PNG_CONST png_byte sbitIn, PNG_CONST int threshold_testIn, PNG_CONST char *name, PNG_CONST int speedIn, PNG_CONST int use_input_precisionIn, PNG_CONST int strip16In) { gamma_display d; context(&pmIn->this, fault); gamma_display_init(&d, pmIn, colour_typeIn, bit_depthIn, interlace_typeIn, file_gammaIn, screen_gammaIn, sbitIn, threshold_testIn, speedIn, use_input_precisionIn, strip16In); Try { png_structp pp; png_infop pi; gamma_modification gamma_mod; srgb_modification srgb_mod; sbit_modification sbit_mod; /* Make an appropriate modifier to set the PNG file gamma to the * given gamma value and the sBIT chunk to the given precision. */ d.pm->modifications = NULL; gamma_modification_init(&gamma_mod, d.pm, d.file_gamma); srgb_modification_init(&srgb_mod, d.pm, 127/*delete*/); sbit_modification_init(&sbit_mod, d.pm, d.sbit); modification_reset(d.pm->modifications); /* Get a png_struct for writing the image. */ pp = set_modifier_for_read(d.pm, &pi, d.this.id, name); /* Set up gamma processing. */ #ifdef PNG_FLOATING_POINT_SUPPORTED png_set_gamma(pp, d.screen_gamma, d.file_gamma); #else { png_fixed_point s = floor(d.screen_gamma*100000+.5); png_fixed_point f = floor(d.file_gamma*100000+.5); png_set_gamma_fixed(pp, s, f); } #endif /* Introduce the correct read function. */ if (d.pm->this.progressive) { /* Share the row function with the standard implementation. */ png_set_progressive_read_fn(pp, &d, gamma_info, progressive_row, gamma_end); /* Now feed data into the reader until we reach the end: */ modifier_progressive_read(d.pm, pp, pi); } else { /* modifier_read expects a png_modifier* */ png_set_read_fn(pp, d.pm, modifier_read); /* Check the header values: */ png_read_info(pp, pi); /* Process the 'info' requirements. only one image is generated */ gamma_info_imp(&d, pp, pi); sequential_row(&d.this, pp, pi, NULL, d.this.ps->image); gamma_image_validate(&d, pp, pi, d.this.ps->image); } modifier_reset(d.pm); if (d.pm->log && !d.threshold_test && !d.speed) fprintf(stderr, "%d bit %s %s: max error %f (%.2g, %2g%%)\n", d.this.bit_depth, colour_types[d.this.colour_type], d.name, d.maxerrout, d.maxerrabs, 100*d.maxerrpc); /* Log the summary values too. */ if (d.this.colour_type == 0 || d.this.colour_type == 4) { switch (d.this.bit_depth) { case 1: break; case 2: if (d.maxerrout > d.pm->error_gray_2) d.pm->error_gray_2 = d.maxerrout; break; case 4: if (d.maxerrout > d.pm->error_gray_4) d.pm->error_gray_4 = d.maxerrout; break; case 8: if (d.maxerrout > d.pm->error_gray_8) d.pm->error_gray_8 = d.maxerrout; break; case 16: if (d.maxerrout > d.pm->error_gray_16) d.pm->error_gray_16 = d.maxerrout; break; default: png_error(pp, "bad bit depth (internal: 1)"); } } else if (d.this.colour_type == 2 || d.this.colour_type == 6) { switch (d.this.bit_depth) { case 8: if (d.maxerrout > d.pm->error_color_8) d.pm->error_color_8 = d.maxerrout; break; case 16: if (d.maxerrout > d.pm->error_color_16) d.pm->error_color_16 = d.maxerrout; break; default: png_error(pp, "bad bit depth (internal: 2)"); } } } Catch(fault) modifier_reset((png_modifier*)fault); } static void gamma_threshold_test(png_modifier *pm, png_byte colour_type, png_byte bit_depth, int interlace_type, double file_gamma, double screen_gamma) { size_t pos = 0; char name[64]; pos = safecat(name, sizeof name, pos, "threshold "); pos = safecatd(name, sizeof name, pos, file_gamma, 3); pos = safecat(name, sizeof name, pos, "/"); pos = safecatd(name, sizeof name, pos, screen_gamma, 3); (void)gamma_test(pm, colour_type, bit_depth, interlace_type, file_gamma, screen_gamma, bit_depth, 1, name, 0/*speed*/, 0/*no input precision*/, 0/*no strip16*/); } static void perform_gamma_threshold_tests(png_modifier *pm) { png_byte colour_type = 0; png_byte bit_depth = 0; while (next_format(&colour_type, &bit_depth)) { double gamma = 1.0; while (gamma >= .4) { /* There's little point testing the interlacing vs non-interlacing, * but this can be set from the command line. */ gamma_threshold_test(pm, colour_type, bit_depth, pm->interlace_type, gamma, 1/gamma); gamma *= .95; } /* And a special test for sRGB */ gamma_threshold_test(pm, colour_type, bit_depth, pm->interlace_type, .45455, 2.2); if (fail(pm)) return; } } static void gamma_transform_test(png_modifier *pm, PNG_CONST png_byte colour_type, PNG_CONST png_byte bit_depth, PNG_CONST int interlace_type, PNG_CONST double file_gamma, PNG_CONST double screen_gamma, PNG_CONST png_byte sbit, PNG_CONST int speed, PNG_CONST int use_input_precision, PNG_CONST int strip16) { size_t pos = 0; char name[64]; if (sbit != bit_depth) { pos = safecat(name, sizeof name, pos, "sbit("); pos = safecatn(name, sizeof name, pos, sbit); pos = safecat(name, sizeof name, pos, ") "); } else pos = safecat(name, sizeof name, pos, "gamma "); if (strip16) pos = safecat(name, sizeof name, pos, "16to8 "); pos = safecatd(name, sizeof name, pos, file_gamma, 3); pos = safecat(name, sizeof name, pos, "->"); pos = safecatd(name, sizeof name, pos, screen_gamma, 3); gamma_test(pm, colour_type, bit_depth, interlace_type, file_gamma, screen_gamma, sbit, 0, name, speed, use_input_precision, strip16); } static void perform_gamma_transform_tests(png_modifier *pm, int speed) { png_byte colour_type = 0; png_byte bit_depth = 0; /* Ignore palette images - the gamma correction happens on the palette entry, * haven't got the tests for this yet. */ while (next_format(&colour_type, &bit_depth)) if (colour_type != 3) { unsigned int i, j; for (i=0; ingammas; ++i) for (j=0; jngammas; ++j) if (i != j) { gamma_transform_test(pm, colour_type, bit_depth, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], bit_depth, speed, pm->use_input_precision, 0/*do not strip16*/); if (fail(pm)) return; } } } static void perform_gamma_sbit_tests(png_modifier *pm, int speed) { png_byte sbit; /* The only interesting cases are colour and grayscale, alpha is ignored here * for overall speed. Only bit depths 8 and 16 are tested. */ for (sbit=pm->sbitlow; sbit<(1<ngammas; ++i) { for (j=0; jngammas; ++j) { if (i != j) { if (sbit < 8) { gamma_transform_test(pm, 0, 8, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], sbit, speed, pm->use_input_precision_sbit, 0/*strip16*/); if (fail(pm)) return; gamma_transform_test(pm, 2, 8, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], sbit, speed, pm->use_input_precision_sbit, 0/*strip16*/); if (fail(pm)) return; } #ifdef DO_16BIT gamma_transform_test(pm, 0, 16, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], sbit, speed, pm->use_input_precision_sbit, 0/*strip16*/); if (fail(pm)) return; gamma_transform_test(pm, 2, 16, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], sbit, speed, pm->use_input_precision_sbit, 0/*strip16*/); if (fail(pm)) return; #endif } } } } } /* Note that this requires a 16 bit source image but produces 8 bit output, so * we only need the 16bit write support. */ #ifdef PNG_WRITE_16BIT_SUPPORTED static void perform_gamma_strip16_tests(png_modifier *pm, int speed) { # ifndef PNG_MAX_GAMMA_8 # define PNG_MAX_GAMMA_8 11 # endif /* Include the alpha cases here, not that sbit matches the internal value * used by the library - otherwise we will get spurious errors from the * internal sbit style approximation. * * The threshold test is here because otherwise the 16 to 8 conversion will * proceed *without* gamma correction, and the tests above will fail (but not * by much) - this could be fixed, it only appears with the -g option. */ unsigned int i, j; for (i=0; ingammas; ++i) { for (j=0; jngammas; ++j) { if (i != j && fabs(pm->gammas[j]/pm->gammas[i]-1) >= PNG_GAMMA_THRESHOLD) { gamma_transform_test(pm, 0, 16, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], PNG_MAX_GAMMA_8, speed, pm->use_input_precision_16to8, 1/*strip16*/); if (fail(pm)) return; gamma_transform_test(pm, 2, 16, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], PNG_MAX_GAMMA_8, speed, pm->use_input_precision_16to8, 1/*strip16*/); if (fail(pm)) return; gamma_transform_test(pm, 4, 16, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], PNG_MAX_GAMMA_8, speed, pm->use_input_precision_16to8, 1/*strip16*/); if (fail(pm)) return; gamma_transform_test(pm, 6, 16, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], PNG_MAX_GAMMA_8, speed, pm->use_input_precision_16to8, 1/*strip16*/); if (fail(pm)) return; } } } } #endif static void perform_gamma_test(png_modifier *pm, int speed, int summary) { /* First some arbitrary no-transform tests: */ if (!speed) { perform_gamma_threshold_tests(pm); if (fail(pm)) return; } /* Now some real transforms. */ perform_gamma_transform_tests(pm, speed); if (summary) { printf("Gamma correction error summary (output value error):\n"); printf(" 2 bit gray: %.5f\n", pm->error_gray_2); printf(" 4 bit gray: %.5f\n", pm->error_gray_4); printf(" 8 bit gray: %.5f\n", pm->error_gray_8); printf(" 8 bit color: %.5f\n", pm->error_color_8); #ifdef DO_16BIT printf(" 16 bit gray: %.5f\n", pm->error_gray_16); printf(" 16 bit color: %.5f\n", pm->error_color_16); #endif } /* The sbit tests produce much larger errors: */ pm->error_gray_2 = pm->error_gray_4 = pm->error_gray_8 = pm->error_gray_16 = pm->error_color_8 = pm->error_color_16 = 0; perform_gamma_sbit_tests(pm, speed); if (summary) { printf("Gamma correction with sBIT:\n"); if (pm->sbitlow < 8U) { printf(" 2 bit gray: %.5f\n", pm->error_gray_2); printf(" 4 bit gray: %.5f\n", pm->error_gray_4); printf(" 8 bit gray: %.5f\n", pm->error_gray_8); printf(" 8 bit color: %.5f\n", pm->error_color_8); } #ifdef DO_16BIT printf(" 16 bit gray: %.5f\n", pm->error_gray_16); printf(" 16 bit color: %.5f\n", pm->error_color_16); #endif } #ifdef PNG_WRITE_16BIT_SUPPORTED /* The 16 to 8 bit strip operations: */ pm->error_gray_2 = pm->error_gray_4 = pm->error_gray_8 = pm->error_gray_16 = pm->error_color_8 = pm->error_color_16 = 0; perform_gamma_strip16_tests(pm, speed); if (summary) { printf("Gamma correction with 16 to 8 bit reduction:\n"); printf(" 16 bit gray: %.5f\n", pm->error_gray_16); printf(" 16 bit color: %.5f\n", pm->error_color_16); } #endif } /* main program */ int main(int argc, PNG_CONST char **argv) { volatile int summary = 1; /* Print the error sumamry at the end */ /* Create the given output file on success: */ PNG_CONST char *volatile touch = NULL; /* This is an array of standard gamma values (believe it or not I've seen * every one of these mentioned somewhere.) * * In the following list the most useful values are first! */ static double gammas[]={2.2, 1.0, 2.2/1.45, 1.8, 1.5, 2.4, 2.5, 2.62, 2.9}; png_modifier pm; context(&pm.this, fault); modifier_init(&pm); /* Preallocate the image buffer, because we know how big it needs to be, * note that, for testing purposes, it is deliberately mis-aligned. */ pm.this.image = malloc(2*STD_IMAGEMAX+1); if (pm.this.image != NULL) { /* Ignore OOM at this point - the 'ensure' routine above will allocate the * array appropriately. */ ++(pm.this.image); pm.this.cb_image = 2*STD_IMAGEMAX; } /* Default to error on warning: */ pm.this.treat_warnings_as_errors = 1; /* Store the test gammas */ pm.gammas = gammas; pm.ngammas = 3U; /* for speed */ pm.sbitlow = 8U; /* because libpng doesn't do sBIT below 8! */ pm.use_input_precision_16to8 = 1U; /* Because of the way libpng does it */ /* Some default values (set the behavior for 'make check' here) */ pm.maxout8 = .1; /* Arithmetic error in *encoded* value */ pm.maxabs8 = .00005; /* 1/20000 */ pm.maxpc8 = .499; /* I.e. .499% fractional error */ pm.maxout16 = .499; /* Error in *encoded* value */ pm.maxabs16 = .00005;/* 1/20000 */ /* NOTE: this is a reasonable perceptual limit, we assume that humans can * perceive light level differences of 1% over a 100:1 range, so we need to * maintain 1 in 10000 accuracy (in linear light space), this is what the * following guarantees. It also allows significantly higher errors at * higher 16 bit values, which is important for performance. The actual * maximum 16 bit error is about +/-1.9 in the fixed point implementation but * this is only allowed for values >38149 by the following: */ pm.maxpc16 = .005; /* I.e. 1/200% - 1/20000 */ /* Now parse the command line options. */ while (--argc >= 1) { if (strcmp(*++argv, "-v") == 0) pm.this.verbose = 1; else if (strcmp(*argv, "-l") == 0) pm.log = 1; else if (strcmp(*argv, "-q") == 0) summary = pm.this.verbose = pm.log = 0; else if (strcmp(*argv, "-g") == 0) pm.ngammas = (sizeof gammas)/(sizeof gammas[0]); else if (strcmp(*argv, "-w") == 0) pm.this.treat_warnings_as_errors = 0; else if (strcmp(*argv, "--speed") == 0) pm.this.speed = 1, pm.ngammas = (sizeof gammas)/(sizeof gammas[0]); else if (strcmp(*argv, "--progressive-read") == 0) pm.this.progressive = 1; else if (strcmp(*argv, "--interlace") == 0) pm.interlace_type = PNG_INTERLACE_ADAM7; else if (argc >= 1 && strcmp(*argv, "--sbitlow") == 0) --argc, pm.sbitlow = (png_byte)atoi(*++argv); else if (argc >= 1 && strcmp(*argv, "--touch") == 0) --argc, touch = *++argv; else if (argc >= 1 && strncmp(*argv, "--max", 4) == 0) { --argc; if (strcmp(4+*argv, "abs8") == 0) pm.maxabs8 = atof(*++argv); else if (strcmp(4+*argv, "abs16") == 0) pm.maxabs16 = atof(*++argv); else if (strcmp(4+*argv, "out8") == 0) pm.maxout8 = atof(*++argv); else if (strcmp(4+*argv, "out16") == 0) pm.maxout16 = atof(*++argv); else if (strcmp(4+*argv, "pc8") == 0) pm.maxpc8 = atof(*++argv); else if (strcmp(4+*argv, "pc16") == 0) pm.maxpc16 = atof(*++argv); else { fprintf(stderr, "pngvalid: %s: unknown 'max' option\n", *argv); exit(1); } } else { fprintf(stderr, "pngvalid: %s: unknown argument\n", *argv); exit(1); } } Try { /* Make useful base images */ make_standard_images(&pm.this); /* Perform the standard and gamma tests. */ if (!pm.this.speed) { perform_standard_test(&pm); perform_error_test(&pm); } perform_gamma_test(&pm, pm.this.speed != 0, summary && !pm.this.speed); } Catch(fault) { fprintf(stderr, "pngvalid: test aborted (probably failed in cleanup)\n"); if (!pm.this.verbose) { if (pm.this.error[0] != 0) fprintf(stderr, "pngvalid: first error: %s\n", pm.this.error); fprintf(stderr, "pngvalid: run with -v to see what happened\n"); } exit(1); } if (summary && !pm.this.speed) { printf("Results using %s point arithmetic %s\n", #if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || PNG_LIBPNG_VER < 10500 "floating", #else "fixed", #endif (pm.this.nerrors || (pm.this.treat_warnings_as_errors && pm.this.nwarnings)) ? "(errors)" : (pm.this.nwarnings ? "(warnings)" : "(no errors or warnings)") ); printf("Allocated memory statistics (in bytes):\n" "\tread %u maximum single, %u peak, %u total\n" "\twrite %u maximum single, %u peak, %u total\n", pm.this.read_memory_pool.max_max, pm.this.read_memory_pool.max_limit, pm.this.read_memory_pool.max_total, pm.this.write_memory_pool.max_max, pm.this.write_memory_pool.max_limit, pm.this.write_memory_pool.max_total); } /* Do this here to provoke memory corruption errors in memory not directly * allocated by libpng - not a complete test, but better than nothing. */ store_delete(&pm.this); /* Error exit if there are any errors, and maybe if there are any * warnings. */ if (pm.this.nerrors || (pm.this.treat_warnings_as_errors && pm.this.nwarnings)) { if (!pm.this.verbose) fprintf(stderr, "pngvalid: %s\n", pm.this.error); fprintf(stderr, "pngvalid: %d errors, %d warnings\n", pm.this.nerrors, pm.this.nwarnings); exit(1); } /* Success case. */ if (touch != NULL) { FILE *fsuccess = fopen(touch, "wt"); if (fsuccess != NULL) { int error = 0; fprintf(fsuccess, "PNG validation succeeded\n"); fflush(fsuccess); error = ferror(fsuccess); if (fclose(fsuccess) || error) { fprintf(stderr, "%s: write failed\n", touch); exit(1); } } } return 0; }