[devel] Reverted changes to call png_longjmp in contrib/gregbook
where it is not appropriate. If mainprog->jmpbuf is used by setjmp,
then png_longjmp cannot be used.
Reversed patch to remove error handler when the jmp_buf is stored in the
main program structure, not the png_struct.
The error handler is needed because the default handler in libpng will
always use the jmp_buf in the library control structure; this is never
set. The gregbook code is a useful example because, even though it
uses setjmp/longjmp, it shows how error handling can be implemented
using control mechanisms not directly supported by libpng. The
technique will work correctly with mechanisms such as Microsoft
Structure Exceptions or C++ exceptions (compiler willing - note that gcc
does not by default support interworking of C and C++ error handling.)
diff --git a/ANNOUNCE b/ANNOUNCE
index 855b8c7..c47edd4 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,5 +1,5 @@
-Libpng 1.5.0beta33 - June 26, 2010
+Libpng 1.5.0beta33 - June 29, 2010
This is not intended to be a public release. It will be replaced
within a few weeks by a public version or by another test version.
@@ -77,6 +77,7 @@
version 1.5.0beta11 [March 6, 2010]
Removed checking for already-included setjmp.h from pngconf.h
Fixed inconsistent indentations and made numerous cosmetic changes.
+ Revised the "SEE ALSO" style of libpng.3, libpngpf.3, and png.5
version 1.5.0beta12 [March 9, 2010]
Moved "#include png.h" inside pngpriv.h and removed "#include png.h" from
@@ -225,7 +226,7 @@
offset of the png_ptr->rowbuf pointer into png_ptr->big_row_buf.
Added more blank lines for readability.
-version 1.5.0beta25 [June 26, 2010]
+version 1.5.0beta25 [June 29, 2010]
In pngpread.c: png_push_have_row() add check for new_row > height
Removed the now-redundant check for out-of-bounds new_row from example.c
@@ -251,16 +252,29 @@
Revised pngpread.c patch of beta28 to avoid an endless loop.
Removed some trailing blanks.
-version 1.5.0beta32 [June 26, 2010]
+version 1.5.0beta32 [June 29, 2010]
Removed leftover scripts/options.patch and scripts/options.rej
-version 1.5.0beta32 [June 26, 2010]
+version 1.5.0beta32 [June 29, 2010]
Made FIXED and FLOATING options consistent in the APIs they enable and
disable. Corrected scripts/options.awk to handle both command line
options and options specified in the .dfa files.
Changed char *msg to PNG_CONST char *msg in pngrutil.c
Make png_set_sRGB_gAMA_and_cHRM set values using either the fixed or
floating point APIs, but not both.
+ Reversed patch to remove error handler when the jmp_buf is stored in the
+ main program structure, not the png_struct.
+ The error handler is needed because the default handler in libpng will
+ always use the jmp_buf in the library control structure; this is never
+ set. The gregbook code is a useful example because, even though it
+ uses setjmp/longjmp, it shows how error handling can be implemented
+ using control mechanisms not directly supported by libpng. The
+ technique will work correctly with mechanisms such as Microsoft
+ Structure Exceptions or C++ exceptions (compiler willing - note that gcc
+ does not by default support interworking of C and C++ error handling.)
+ Reverted changes to call png_longjmp in contrib/gregbook where it is not
+ appropriate. If mainprog->jmpbuf is used by setjmp, then png_longjmp
+ cannot be used.
Send comments/corrections/commendations to png-mng-implement at lists.sf.net:
(subscription required; visit
diff --git a/CHANGES b/CHANGES
index f6b6731..e9cb0f4 100644
--- a/CHANGES
+++ b/CHANGES
@@ -2557,6 +2557,7 @@
version 1.5.0beta11 [March 6, 2010]
Removed checking for already-included setjmp.h from pngconf.h
Fixed inconsistent indentations and made numerous cosmetic changes.
+ Revised the "SEE ALSO" style of libpng.3, libpngpf.3, and png.5
version 1.5.0beta12 [March 9, 2010]
Moved "#include png.h" inside pngpriv.h and removed "#include png.h" from
@@ -2736,13 +2737,26 @@
version 1.5.0beta32 [June 26, 2010]
Removed leftover scripts/options.patch and scripts/options.rej
-version 1.5.0beta33 [June 26, 2010]
+version 1.5.0beta33 [June 29, 2010]
Made FIXED and FLOATING options consistent in the APIs they enable and
disable. Corrected scripts/options.awk to handle both command line
options and options specified in the .dfa files.
Changed char *msg to PNG_CONST char *msg in pngrutil.c
Make png_set_sRGB_gAMA_and_cHRM set values using either the fixed or
floating point APIs, but not both.
+ Reversed patch to remove error handler when the jmp_buf is stored in the
+ main program structure, not the png_struct.
+ The error handler is needed because the default handler in libpng will
+ always use the jmp_buf in the library control structure; this is never
+ set. The gregbook code is a useful example because, even though it
+ uses setjmp/longjmp, it shows how error handling can be implemented
+ using control mechanisms not directly supported by libpng. The
+ technique will work correctly with mechanisms such as Microsoft
+ Structure Exceptions or C++ exceptions (compiler willing - note that gcc
+ does not by default support interworking of C and C++ error handling.)
+ Reverted changes to call png_longjmp in contrib/gregbook where it is not
+ appropriate. If mainprog->jmpbuf is used by setjmp, then png_longjmp
+ cannot be used.
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit
diff --git a/contrib/gregbook/readpng2.c b/contrib/gregbook/readpng2.c
index 42addbf..4644b09 100644
--- a/contrib/gregbook/readpng2.c
+++ b/contrib/gregbook/readpng2.c
@@ -66,6 +66,7 @@
static void readpng2_row_callback(png_structp png_ptr, png_bytep new_row,
png_uint_32 row_num, int pass);
static void readpng2_end_callback(png_structp png_ptr, png_infop info_ptr);
+static void readpng2_error_handler(png_structp png_ptr, png_const_charp msg);
@@ -101,7 +102,7 @@
/* could also replace libpng warning-handler (final NULL), but no need: */
png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, mainprog_ptr,
- NULL, NULL);
+ readpng2_error_handler, NULL);
if (!png_ptr)
return 4; /* out of memory */
@@ -450,3 +451,41 @@
mainprog_ptr->png_ptr = NULL;
mainprog_ptr->info_ptr = NULL;
}
+
+
+
+
+
+static void readpng2_error_handler(png_structp png_ptr, png_const_charp msg)
+{
+ mainprog_info *mainprog_ptr;
+
+ /* This function, aside from the extra step of retrieving the "error
+ * pointer" (below) and the fact that it exists within the application
+ * rather than within libpng, is essentially identical to libpng's
+ * default error handler. The second point is critical: since both
+ * setjmp() and longjmp() are called from the same code, they are
+ * guaranteed to have compatible notions of how big a jmp_buf is,
+ * regardless of whether _BSD_SOURCE or anything else has (or has not)
+ * been defined. */
+
+ fprintf(stderr, "readpng2 libpng error: %s\n", msg);
+ fflush(stderr);
+
+ mainprog_ptr = png_get_error_ptr(png_ptr);
+ if (mainprog_ptr == NULL) { /* we are completely hosed now */
+ fprintf(stderr,
+ "readpng2 severe error: jmpbuf not recoverable; terminating.\n");
+ fflush(stderr);
+ exit(99);
+ }
+
+ /* Now we have our data structure we can use the information in it
+ * to return control to our own higher level code (all the points
+ * where 'setjmp' is called in this file.) This will work with other
+ * error handling mechanisms as well - libpng always calls png_error
+ * when it can proceed no further, thus, so long as the error handler
+ * is intercepted, application code can do its own error recovery.
+ */
+ longjmp(mainprog_ptr->jmpbuf, 1);
+}
diff --git a/contrib/gregbook/rpng-win.c b/contrib/gregbook/rpng-win.c
index 543a0bb..2020961 100644
--- a/contrib/gregbook/rpng-win.c
+++ b/contrib/gregbook/rpng-win.c
@@ -24,8 +24,6 @@
- 1.10: enabled "message window"/console (thanks to David Geldreich)
- 2.00: dual-licensed (added GNU GPL)
- 2.01: fixed improper display of usage screen on PNG error(s)
- - 2.02: removed special error-handling which is no longer needed
- because of the new libpng png_longjmp() feature in libpng-1.5.0.
---------------------------------------------------------------------------
diff --git a/contrib/gregbook/rpng-x.c b/contrib/gregbook/rpng-x.c
index e2dd19b..e821cfb 100644
--- a/contrib/gregbook/rpng-x.c
+++ b/contrib/gregbook/rpng-x.c
@@ -26,8 +26,6 @@
- 1.14: added support for X resources (thanks to Gerhard Niklasch)
- 2.00: dual-licensed (added GNU GPL)
- 2.01: fixed improper display of usage screen on PNG error(s)
- - 2.02: removed special error-handling which is no longer needed
- because of the new libpng png_longjmp() feature in libpng-1.5.0.
---------------------------------------------------------------------------
diff --git a/contrib/gregbook/rpng2-win.c b/contrib/gregbook/rpng2-win.c
index 638024b..8c831db 100644
--- a/contrib/gregbook/rpng2-win.c
+++ b/contrib/gregbook/rpng2-win.c
@@ -32,9 +32,7 @@
- 2.01: fixed 64-bit typo in readpng2.c
- 2.02: fixed improper display of usage screen on PNG error(s); fixed
unexpected-EOF and file-read-error cases
- - 2.03: removed runtime MMX-enabling/disabling and obsolete -mmx* options;
- removed special error-handling which is no longer needed
- because of the new libpng png_longjmp() feature in libpng-1.5.0.
+ - 2.03: removed runtime MMX-enabling/disabling and obsolete -mmx* options
---------------------------------------------------------------------------
diff --git a/contrib/gregbook/rpng2-x.c b/contrib/gregbook/rpng2-x.c
index 206b00a..2c24734 100644
--- a/contrib/gregbook/rpng2-x.c
+++ b/contrib/gregbook/rpng2-x.c
@@ -41,8 +41,6 @@
unexpected-EOF and file-read-error cases; fixed Trace() cut-and-
paste bugs
- 2.03: deleted runtime MMX-enabling/disabling and obsolete -mmx* options
- removed special error-handling which is no longer needed
- because of the new libpng png_longjmp() feature in libpng-1.5.0.
---------------------------------------------------------------------------
@@ -786,8 +784,9 @@
if (rpng2_x_create_window()) {
/* GRR TEMPORARY HACK: this is fundamentally no different from cases
- * above; libpng should longjmp() back to us when png_ptr goes away.
- * If we/it segfault instead, seems like a libpng bug... */
+ * above; libpng should call our error handler to longjmp() back to us
+ * when png_ptr goes away. If we/it segfault instead, seems like a
+ * libpng bug... */
/* we're here via libpng callback, so if window fails, clean and bail */
readpng2_cleanup(&rpng2_info);
diff --git a/contrib/gregbook/wpng.c b/contrib/gregbook/wpng.c
index 753fef3..a06e352 100644
--- a/contrib/gregbook/wpng.c
+++ b/contrib/gregbook/wpng.c
@@ -29,8 +29,6 @@
- 1.04: fixed DOS/OS2/Win32 detection, including partial Cygwin fix
(see http://home.att.net/~perlspinr/diffs/GregBook_cygwin.diff)
- 2.00: dual-licensed (added GNU GPL)
- - 2.01: removed special error-handling which is no longer needed
- because of the new libpng png_longjmp() feature in libpng-1.5.0.
[REPORTED BUG (win32 only): "contrib/gregbook/wpng.c - cmd line
dose not work! In order to do something useful I needed to redirect
diff --git a/contrib/gregbook/writepng.c b/contrib/gregbook/writepng.c
index 1d67f89..f07f4a8 100644
--- a/contrib/gregbook/writepng.c
+++ b/contrib/gregbook/writepng.c
@@ -60,6 +60,10 @@
#include "writepng.h" /* typedefs, common macros, public prototypes */
+/* local prototype */
+
+static void writepng_error_handler(png_structp png_ptr, png_const_charp msg);
+
void writepng_version_info(void)
@@ -86,7 +90,7 @@
/* could also replace libpng warning-handler (final NULL), but no need: */
png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, mainprog_ptr,
- NULL, NULL);
+ writepng_error_handler, NULL);
if (!png_ptr)
return 4; /* out of memory */
@@ -100,7 +104,8 @@
/* setjmp() must be called in every function that calls a PNG-writing
* libpng function, unless an alternate error handler was installed--
* but compatible error handlers must either use longjmp() themselves
- * (as in this program) or exit immediately, so here we go: */
+ * (as in this program) or some other method to return control to
+ * application code, so here we go: */
if (setjmp(mainprog_ptr->jmpbuf)) {
png_destroy_write_struct(&png_ptr, &info_ptr);
@@ -355,3 +360,41 @@
if (png_ptr && info_ptr)
png_destroy_write_struct(&png_ptr, &info_ptr);
}
+
+
+
+
+
+static void writepng_error_handler(png_structp png_ptr, png_const_charp msg)
+{
+ mainprog_info *mainprog_ptr;
+
+ /* This function, aside from the extra step of retrieving the "error
+ * pointer" (below) and the fact that it exists within the application
+ * rather than within libpng, is essentially identical to libpng's
+ * default error handler. The second point is critical: since both
+ * setjmp() and longjmp() are called from the same code, they are
+ * guaranteed to have compatible notions of how big a jmp_buf is,
+ * regardless of whether _BSD_SOURCE or anything else has (or has not)
+ * been defined. */
+
+ fprintf(stderr, "writepng libpng error: %s\n", msg);
+ fflush(stderr);
+
+ mainprog_ptr = png_get_error_ptr(png_ptr);
+ if (mainprog_ptr == NULL) { /* we are completely hosed now */
+ fprintf(stderr,
+ "writepng severe error: jmpbuf not recoverable; terminating.\n");
+ fflush(stderr);
+ exit(99);
+ }
+
+ /* Now we have our data structure we can use the information in it
+ * to return control to our own higher level code (all the points
+ * where 'setjmp' is called in this file.) This will work with other
+ * error handling mechanisms as well - libpng always calls png_error
+ * when it can proceed no further, thus, so long as the error handler
+ * is intercepted, application code can do its own error recovery.
+ */
+ longjmp(mainprog_ptr->jmpbuf, 1);
+}
