[master] Pass "" instead of '\0' to png_default_error() in png_err().

This mistake was introduced in libpng-1.2.20beta01.

3 files changed, 14 insertions, 5 deletions

diff --git a/ANNOUNCE b/ANNOUNCE
index eaab5cbb7..3e8d9f3c1 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,5 +1,5 @@
 
-Libpng 1.4.8beta01 - May 2, 2011
+Libpng 1.4.8beta01 - June 4, 2011
 
 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.
@@ -26,10 +26,12 @@ Other information:
 
 Changes since the last public release (1.4.7):
 
-version 1.4.8beta01 [May 2, 2011]
+version 1.4.8beta01 [June 4, 2011]
   Undef "_ALL_SOURCE" for AIX, to prevent "jmpbuf" from being redefined.
   Copied png_debug macros from pngpriv.h into pngtest.c and removed
     "#include pngpriv.h" from pngtest.c, to avoid setting a bad example.
+  Pass "" instead of '\0' to png_default_error() in png_err().  This mistake
+    was introduced in libpng-1.2.20beta01.
 
 Send comments/corrections/commendations to glennrp at users.sourceforge.net
 or to png-mng-implement at lists.sf.net (subscription required; visit
diff --git a/CHANGES b/CHANGES
index 4311a6d5c..ef70ac382 100644
--- a/CHANGES
+++ b/CHANGES
@@ -2794,10 +2794,12 @@ version 1.4.7rc01 [April 9, 2011]
 version 1.4.7 [April 9, 2011]
   Disabled PNG_PEDANTIC_WARNINGS for all MSC versions as in libpng-1.4.5.
 
-version 1.4.8beta01 [May 2, 2011]
+version 1.4.8beta01 [June 4, 2011]
   Undef "_ALL_SOURCE" for AIX, to prevent "jmpbuf" from being redefined.
   Copied png_debug macros from pngpriv.h into pngtest.c and removed
     "#include pngpriv.h" from pngtest.c, to avoid setting a bad example.
+  Pass "" instead of '\0' to png_default_error() in png_err().  This mistake
+    was introduced in libpng-1.2.20beta01.
 
 Send comments/corrections/commendations to glennrp at users.sourceforge.net
 or to png-mng-implement at lists.sf.net (subscription required; visit
diff --git a/pngerror.c b/pngerror.c
index c196b11ce..9798fb712 100644
--- a/pngerror.c
+++ b/pngerror.c
@@ -87,12 +87,17 @@ png_error(png_structp png_ptr, png_const_charp error_message)
 void PNGAPI
 png_err(png_structp png_ptr)
 {
+   /* Prior to 1.4.8 the error_fn received a NULL pointer, expressed
+    * erroneously as '\0', instead of the empty string "".  This was
+    * apparently an error, introduced in libpng-1.2.20, and png_default_error
+    * will crash in this case.
+    */
    if (png_ptr != NULL && png_ptr->error_fn != NULL)
-      (*(png_ptr->error_fn))(png_ptr, '\0');
+      (*(png_ptr->error_fn))(png_ptr, "");
 
    /* If the custom handler doesn't exist, or if it returns,
       use the default handler, which will not return. */
-   png_default_error(png_ptr, '\0');
+   png_default_error(png_ptr, "");
 }
 #endif /* PNG_ERROR_TEXT_SUPPORTED */