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Fix compiler warning and potential error in PNG error handling.

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Compilation with gcc -Wall -Wextra displayed the following warning:

Fl_PNG_Image.cxx: In member function ‘void Fl_PNG_Image::load_png_(const char*, const unsigned char*, int)’:
Fl_PNG_Image.cxx:118:9: warning: variable ‘fp’ might be clobbered by ‘longjmp’ or ‘vfork’ [-Wclobbered]

Making the variable static and initializing it properly avoids this
potential error in the PNG lib's error handling.


git-svn-id: file:///fltk/svn/fltk/branches/branch-1.4@12439 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
This commit is contained in:
Albrecht Schlosser 2017-09-10 11:38:23 +00:00
parent 4a8e829f09
commit b0a2223642
2 changed files with 22 additions and 14 deletions
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2
CHANGES
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@ -92,6 +92,8 @@ Changes in FLTK 1.4.0 Released: ??? ?? 2017
Bug Fixes
- (add new items here)
- Fix Fl_PNG_Image error handling. An error was potentially caused
by error handling of the image library with setjmp/longjmp.
- Fix Fl_Browser background and text color parsing (STR #3376).
- Fix Windows CreateDC/DeleteDC mismatch (STR #3373).
- Fix Fl_Tabs label drawing for Fl_Window children (STR #3075).

34
src/Fl_PNG_Image.cxx
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@ -6,6 +6,8 @@
// Copyright 1997-2012 by Easy Software Products.
// Image support by Matthias Melcher, Copyright 2000-2009.
//
// Copyright 2013-2017 by Bill Spitzak and others.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file. If this
// file is missing or damaged, see the license at:
@ -31,9 +33,10 @@
#include <FL/Fl_System_Driver.H>
#include <FL/Fl_PNG_Image.H>
#include <FL/Fl_Shared_Image.H>
#include <FL/fl_utf8.h>
#include <stdio.h>
#include <stdlib.h>
#include <FL/fl_utf8.h>
#if defined(HAVE_LIBPNG) && defined(HAVE_LIBZ)
extern "C"
@ -90,14 +93,14 @@ Fl_PNG_Image::Fl_PNG_Image (const char *filename): Fl_RGB_Image(0,0,0)
}
/**
/**
\brief Constructor that reads a PNG image from memory.
Construct an image from a block of memory inside the application. Fluid offers
"binary Data" chunks as a great way to add image data into the C++ source code.
name_png can be NULL. If a name is given, the image is added to the list of
name_png can be NULL. If a name is given, the image is added to the list of
shared images (see: Fl_Shared_Image) and will be available by that name.
\param name_png A name given to this image or NULL
\param buffer Pointer to the start of the PNG image in memory
\param maxsize Size in bytes of the memory buffer containing the PNG image
@ -112,15 +115,19 @@ Fl_PNG_Image::Fl_PNG_Image (
void Fl_PNG_Image::load_png_(const char *name_png, const unsigned char *buffer_png, int maxsize)
{
#if defined(HAVE_LIBPNG) && defined(HAVE_LIBZ)
int i; // Looping var
FILE *fp = NULL; // File pointer
int channels; // Number of color channels
png_structp pp; // PNG read pointer
png_infop info = 0; // PNG info pointers
png_bytep *rows;// PNG row pointers
int i; // Looping var
int channels; // Number of color channels
png_structp pp; // PNG read pointer
png_infop info = 0; // PNG info pointers
png_bytep *rows; // PNG row pointers
fl_png_memory png_mem_data;
int from_memory = (buffer_png != NULL); // true if reading image from memory
// Note: The file pointer fp must not be an automatic (stack) variable
// to avoid potential clobbering by setjmp/longjmp (gcc: [-Wclobbered]).
static FILE *fp; // intentionally initialized separately below
fp = NULL; // always initialize file pointer
if (!from_memory) {
if ((fp = fl_fopen(name_png, "rb")) == NULL) {
ld(ERR_FILE_ACCESS);
@ -139,9 +146,8 @@ void Fl_PNG_Image::load_png_(const char *name_png, const unsigned char *buffer_p
w(0); h(0); d(0); ld(ERR_FORMAT);
return;
}
if (setjmp(png_jmpbuf(pp)))
{
if (setjmp(png_jmpbuf(pp))) {
png_destroy_read_struct(&pp, &info, NULL);
if (!from_memory) fclose(fp);
Fl::warning("PNG file or data \"%s\" is too large or contains errors!\n", display_name);
@ -157,7 +163,7 @@ void Fl_PNG_Image::load_png_(const char *name_png, const unsigned char *buffer_p
png_set_read_fn (pp, (png_voidp) &png_mem_data, png_read_data_from_mem);
} else {
png_init_io(pp, fp); // Initialize the PNG file read "engine"...
}
}
// Get the image dimensions and convert to grayscale or RGB...
png_read_info(pp, info);