Deimplementing complications in libpng18

Makefile.am

@@ -284,7 +284,7 @@ pnglibconf.c: scripts/pnglibconf/pnglibconf.dfa scripts/pnglibconf/options.awk p
 	mv $*.tf5 $@
 
 # Symbol checks (.def and .out files should match)
-scripts/pnglibconf/symbols.chk: scripts/pnglibconf/checksym.awk scripts/pnglibconf/symbols.def \
+scripts/pnglibconf/symbols.chk: scripts/pnglibconf/checksym.awk scripts/symbols.def \
                                 scripts/pnglibconf/symbols.out
 
 .out.chk:

contrib/examples/pngpixel.c

@@ -184,11 +184,11 @@ int main(int argc, const char **argv)
                      compression_method, filter_method;
                   png_bytep row_tmp;
 
-                  /* Now associate the recently opened (FILE*) with the default
-                   * libpng initialization functions.  Sometimes libpng is
-                   * compiled without stdio support (it can be difficult to do
-                   * in some environments); in that case you will have to write
-                   * your own read callback to read data from the (FILE*).
+                  /* Now associate the recently opened FILE object with the
+                   * default libpng initialization functions.  Sometimes libpng
+                   * is compiled without stdio support (it can be difficult to
+                   * do in some environments); in that case you will have to
+                   * write your own read callback to read data from the stream.
                    */
                   png_init_io(png_ptr, f);
 

contrib/libtests/makepng.c

@@ -745,7 +745,7 @@ generate_row(png_bytep row, size_t rowbytes, unsigned int y, int color_type,
 }
 
 
-static void PNGCBAPI
+static void
 makepng_warning(png_structp png_ptr, png_const_charp message)
 {
    const char **ep = png_get_error_ptr(png_ptr);
@@ -760,7 +760,7 @@ makepng_warning(png_structp png_ptr, png_const_charp message)
   fprintf(stderr, "%s: warning: %s\n", name, message);
 }
 
-static void PNGCBAPI
+static void
 makepng_error(png_structp png_ptr, png_const_charp message)
 {
    makepng_warning(png_ptr, message);

contrib/libtests/pngimage.c

@@ -768,13 +768,13 @@ display_log(struct display *dp, error_level level, const char *fmt, ...)
 }
 
 /* error handler callbacks for libpng */
-static void PNGCBAPI
+static void
 display_warning(png_structp pp, png_const_charp warning)
 {
    display_log(get_dp(pp), LIBPNG_WARNING, "%s", warning);
 }
 
-static void PNGCBAPI
+static void
 display_error(png_structp pp, png_const_charp error)
 {
    struct display *dp = get_dp(pp);
@@ -858,7 +858,7 @@ buffer_read(struct display *dp, struct buffer *bp, png_bytep data,
    bp->read_count = read_count;
 }
 
-static void PNGCBAPI
+static void
 read_function(png_structp pp, png_bytep data, size_t size)
 {
    buffer_read(get_dp(pp), get_buffer(pp), data, size);
@@ -1325,7 +1325,7 @@ buffer_write(struct display *dp, struct buffer *buffer, png_bytep data,
    buffer->end_count = end_count;
 }
 
-static void PNGCBAPI
+static void
 write_function(png_structp pp, png_bytep data, size_t size)
 {
    buffer_write(get_dp(pp), get_buffer(pp), data, size);

contrib/libtests/pngstest.c

@@ -593,7 +593,8 @@ newimage(Image *image)
    memset(image, 0, sizeof *image);
 }
 
-/* Reset the image to be read again - only needs to rewind the FILE* at present.
+/* Reset the image to be read again - only needs to rewind the FILE object at
+ * present.
  */
 static void
 resetimage(Image *image)

contrib/libtests/pngunknown.c

@@ -457,7 +457,8 @@ clean_display(display *d)
    }
 }
 
-PNG_FUNCTION(void, display_exit, (display *d), static PNG_NORETURN)
+static PNG_NORETURN void
+display_exit(display *d)
 {
    ++(d->error_count);
 
@@ -480,16 +481,16 @@ display_rc(const display *d, int strict)
 }
 
 /* libpng error and warning callbacks */
-PNG_FUNCTION(void, (PNGCBAPI error), (png_structp png_ptr, const char *message),
-   static PNG_NORETURN)
+static PNG_NORETURN void
+error(png_structp png_ptr, const char *message)
 {
    display *d = (display*)png_get_error_ptr(png_ptr);
 
    fprintf(stderr, "%s(%s): libpng error: %s\n", d->file, d->test, message);
    display_exit(d);
 }
 
-static void PNGCBAPI
+static void
 warning(png_structp png_ptr, const char *message)
 {
    display *d = (display*)png_get_error_ptr(png_ptr);
@@ -531,7 +532,7 @@ get_valid(display *d, png_infop info_ptr)
 }
 
 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
-static int PNGCBAPI
+static int
 read_callback(png_structp pp, png_unknown_chunkp pc)
 {
    /* This function mimics the behavior of png_set_keep_unknown_chunks by

contrib/libtests/pngvalid.c

@@ -1093,7 +1093,7 @@ internal_error(png_store *ps, png_const_charp message)
 #endif /* PNG_READ_SUPPORTED */
 
 /* Functions to use as PNG callbacks. */
-static void PNGCBAPI
+static void
 store_error(png_structp ppIn, png_const_charp message) /* PNG_NORETURN */
 {
    png_const_structp pp = ppIn;
@@ -1109,7 +1109,7 @@ store_error(png_structp ppIn, png_const_charp message) /* PNG_NORETURN */
    }
 }
 
-static void PNGCBAPI
+static void
 store_warning(png_structp ppIn, png_const_charp message)
 {
    png_const_structp pp = ppIn;
@@ -1281,7 +1281,7 @@ valid_chunktype(png_uint_32 chunktype)
    return 1; /* It's valid */
 }
 
-static void PNGCBAPI
+static void
 store_write(png_structp ppIn, png_bytep pb, size_t st)
 {
    png_const_structp pp = ppIn;
@@ -1375,7 +1375,7 @@ store_write(png_structp ppIn, png_bytep pb, size_t st)
    ps->chunklen = chunklen;
 }
 
-static void PNGCBAPI
+static void
 store_flush(png_structp ppIn)
 {
    UNUSED(ppIn) /*DOES NOTHING*/
@@ -1700,7 +1700,7 @@ store_read_chunk(png_store *ps, png_bytep pb, size_t max, size_t min)
    return st; /* space left */
 }
 
-static void PNGCBAPI
+static void
 store_read(png_structp ppIn, png_bytep pb, size_t st)
 {
    png_const_structp pp = ppIn;
@@ -1903,7 +1903,7 @@ store_pool_delete(png_store *ps, store_pool *pool)
 }
 
 /* The memory callbacks: */
-static png_voidp PNGCBAPI
+static png_voidp
 store_malloc(png_structp ppIn, png_alloc_size_t cb)
 {
    png_const_structp pp = ppIn;
@@ -1952,7 +1952,7 @@ store_malloc(png_structp ppIn, png_alloc_size_t cb)
    return new;
 }
 
-static void PNGCBAPI
+static void
 store_free(png_structp ppIn, png_voidp memory)
 {
    png_const_structp pp = ppIn;
@@ -3198,7 +3198,7 @@ modifier_read_imp(png_modifier *pm, png_bytep pb, size_t st)
 }
 
 /* The callback: */
-static void PNGCBAPI
+static void
 modifier_read(png_structp ppIn, png_bytep pb, size_t st)
 {
    png_const_structp pp = ppIn;
@@ -5391,7 +5391,7 @@ standard_info_imp(standard_display *dp, png_structp pp, png_infop pi,
    standard_info_part2(dp, pp, pi, nImages);
 }
 
-static void PNGCBAPI
+static void
 standard_info(png_structp pp, png_infop pi)
 {
    standard_display *dp = voidcast(standard_display*,
@@ -5403,7 +5403,7 @@ standard_info(png_structp pp, png_infop pi)
    standard_info_imp(dp, pp, pi, 1 /*only one image*/);
 }
 
-static void PNGCBAPI
+static void
 progressive_row(png_structp ppIn, png_bytep new_row, png_uint_32 y, int pass)
 {
    png_const_structp pp = ppIn;
@@ -5703,7 +5703,7 @@ standard_image_validate(standard_display *dp, png_const_structp pp, int iImage,
    dp->ps->validated = 1;
 }
 
-static void PNGCBAPI
+static void
 standard_end(png_structp ppIn, png_infop pi)
 {
    png_const_structp pp = ppIn;
@@ -6703,7 +6703,7 @@ transform_info_imp(transform_display *dp, png_structp pp, png_infop pi)
    }
 }
 
-static void PNGCBAPI
+static void
 transform_info(png_structp pp, png_infop pi)
 {
    transform_info_imp(voidcast(transform_display*, png_get_progressive_ptr(pp)),
@@ -6919,7 +6919,7 @@ transform_image_validate(transform_display *dp, png_const_structp pp,
    dp->this.ps->validated = 1;
 }
 
-static void PNGCBAPI
+static void
 transform_end(png_structp ppIn, png_infop pi)
 {
    png_const_structp pp = ppIn;
@@ -9385,7 +9385,7 @@ gamma_info_imp(gamma_display *dp, png_structp pp, png_infop pi)
    standard_info_part2(&dp->this, pp, pi, 1 /*images*/);
 }
 
-static void PNGCBAPI
+static void
 gamma_info(png_structp pp, png_infop pi)
 {
    gamma_info_imp(voidcast(gamma_display*, png_get_progressive_ptr(pp)), pp,
@@ -10385,7 +10385,7 @@ gamma_image_validate(gamma_display *dp, png_const_structp pp,
    dp->this.ps->validated = 1;
 }
 
-static void PNGCBAPI
+static void
 gamma_end(png_structp ppIn, png_infop pi)
 {
    png_const_structp pp = ppIn;

contrib/tools/pngcp.c

@@ -1674,7 +1674,7 @@ makename(struct display *dp, const char *dir, const char *infile)
 }
 
 /* error handler callbacks for libpng */
-static void PNGCBAPI
+static void
 display_warning(png_structp pp, png_const_charp warning)
 {
    struct display *dp = get_dp(pp);
@@ -1684,7 +1684,7 @@ display_warning(png_structp pp, png_const_charp warning)
       display_log(get_dp(pp), LIBPNG_WARNING, "%s", warning);
 }
 
-static void PNGCBAPI
+static void
 display_error(png_structp pp, png_const_charp error)
 {
    struct display *dp = get_dp(pp);
@@ -1716,7 +1716,7 @@ display_start_read(struct display *dp, const char *filename)
       display_log(dp, USER_ERROR, "file open failed (%s)", strerror(errno));
 }
 
-static void PNGCBAPI
+static void
 read_function(png_structp pp, png_bytep data, size_t size)
 {
    struct display *dp = get_dp(pp);
@@ -1896,7 +1896,7 @@ display_start_write(struct display *dp, const char *filename)
    }
 }
 
-static void PNGCBAPI
+static void
 write_function(png_structp pp, png_bytep data, size_t size)
 {
    struct display *dp = get_dp(pp);

contrib/tools/pngfix.c

@@ -3149,13 +3149,13 @@ read_chunk(struct file *file)
 /* This returns a file* from a png_struct in an implementation specific way. */
 static struct file *get_control(png_const_structrp png_ptr);
 
-static void PNGCBAPI
+static void
 error_handler(png_structp png_ptr, png_const_charp message)
 {
    stop(get_control(png_ptr),  LIBPNG_ERROR_CODE, message);
 }
 
-static void PNGCBAPI
+static void
 warning_handler(png_structp png_ptr, png_const_charp message)
 {
    struct file *file = get_control(png_ptr);
@@ -3167,7 +3167,7 @@ warning_handler(png_structp png_ptr, png_const_charp message)
 /* Read callback - this is where the work gets done to check the stream before
  * passing it to libpng
  */
-static void PNGCBAPI
+static void
 read_callback(png_structp png_ptr, png_bytep buffer, size_t count)
    /* Return 'count' bytes to libpng in 'buffer' */
 {

example.c

@@ -2,7 +2,7 @@
 
 /* example.c - an example of using libpng
  *
- * Maintained 2018-2024 Cosmin Truta
+ * Maintained 2018-2025 Cosmin Truta
  * Maintained 1998-2016 Glenn Randers-Pehrson
  * Maintained 1996-1997 Andreas Dilger
  * Written 1995-1996 Guy Eric Schalnat, Group 42, Inc.
@@ -179,11 +179,11 @@ int main(int argc, const char **argv)
  *    components.
  *
  * You do not have to read directly from a file.  You can read from memory or,
- * on systems that support it, from a <stdio.h> FILE*.  This is controlled by
- * the particular png_image_read_from_ function you call at the start.
- * Likewise, on write, you can write to a FILE* if your system supports it.
- * Check the macro PNG_STDIO_SUPPORTED to see if stdio support has been
- * included in your libpng build.
+ * on systems that support <stdio.h>, from a FILE object.  This is controlled
+ * by the particular png_image_read_from_ function you call at the start.
+ * Likewise, on write, you can write to a FILE object if your system supports
+ * <stdio.h>.  The macro PNG_STDIO_SUPPORTED indicates if stdio is available
+ * and accessible from your libpng build.
  *
  * If you read 16-bit (PNG_FORMAT_FLAG_LINEAR) data, you may need to write it
  * in the 8-bit format for display.  You do this by setting the convert_to_8bit

manuals/libpng-install.txt

@@ -345,30 +345,11 @@ way pngusr.h is used in the build has been changed; however, library
 builders will probably want to examine the changes to take advantage of
 new capabilities and to simplify their build system.
 
-A. Specific changes to library configuration capabilities
-
-The exact mechanism used to control attributes of API functions has
-changed.  A single set of operating system independent macro definitions
-is used and operating system specific directives are defined in
-pnglibconf.h
-
-As part of this the mechanism used to choose procedure call standards on
-those systems that allow a choice has been changed.  At present this only
-affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems
-running on Intel processors.  As before, PNGAPI is defined where required
-to control the exported API functions; however, two new macros, PNGCBAPI
-and PNGCAPI, are used instead for callback functions (PNGCBAPI) and
-(PNGCAPI) for functions that must match a C library prototype (currently
-only png_longjmp_ptr, which must match the C longjmp function.)  The new
-approach is documented in pngconf.h
-
-Despite these changes, libpng 1.5.0 only supports the native C function
-calling standard on those platforms tested so far ("__cdecl" on Microsoft
-Windows).  This is because the support requirements for alternative
-calling conventions seem to no longer exist.  Developers who find it
-necessary to set PNG_API_RULE to 1 should advise the mailing list
-(png-mng-implement) of this and library builders who use Openwatcom and
-therefore set PNG_API_RULE to 2 should also contact the mailing list.
+A. Changes to the library configuration capabilities
+
+A new mechanism to control attributes of API functions was introduced in
+libpng-1.5.0.  A single set of system-independent macro definitions and
+directives is defined in pnglibconf.h
 
 B. Changes to the configuration mechanism