Fix #492: Potential double-free in gdImage*Ptr()
Whenever `gdImage*Ptr()` calls `gdImage*Ctx()` and the latter fails, we must not call `gdDPExtractData()`; otherwise a double-free would happen. Since `gdImage*Ctx()` are void functions, and we can't change that for BC reasons, we're introducing static helpers which are used internally. We're adding a regression test for `gdImageJpegPtr()`, but not for `gdImageGifPtr()` and `gdImageWbmpPtr()` since we don't know how to trigger failure of the respective `gdImage*Ctx()` calls. This potential security issue has been reported by Solmaz Salimi (aka. Rooney).master
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a414b9ba3e
commit
553702980a
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@ -99,6 +99,7 @@ static void char_init(GifCtx *ctx);
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static void char_out(int c, GifCtx *ctx);
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static void flush_char(GifCtx *ctx);
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static int _gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out);
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@ -131,8 +132,11 @@ BGD_DECLARE(void *) gdImageGifPtr(gdImagePtr im, int *size)
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void *rv;
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gdIOCtx *out = gdNewDynamicCtx(2048, NULL);
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if (out == NULL) return NULL;
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gdImageGifCtx(im, out);
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rv = gdDPExtractData(out, size);
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if (!_gdImageGifCtx(im, out)) {
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rv = gdDPExtractData(out, size);
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} else {
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rv = NULL;
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}
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out->gd_free(out);
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return rv;
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}
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@ -220,6 +224,12 @@ BGD_DECLARE(void) gdImageGif(gdImagePtr im, FILE *outFile)
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*/
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BGD_DECLARE(void) gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out)
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{
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_gdImageGifCtx(im, out);
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}
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/* returns 0 on success, 1 on failure */
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static int _gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out)
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{
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gdImagePtr pim = 0, tim = im;
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int interlace, BitsPerPixel;
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@ -231,7 +241,7 @@ BGD_DECLARE(void) gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out)
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based temporary image. */
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pim = gdImageCreatePaletteFromTrueColor(im, 1, 256);
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if(!pim) {
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return;
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return 1;
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}
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tim = pim;
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}
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@ -247,6 +257,8 @@ BGD_DECLARE(void) gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out)
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/* Destroy palette based temporary image. */
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gdImageDestroy( pim);
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}
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return 0;
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}
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@ -117,6 +117,8 @@ static void fatal_jpeg_error(j_common_ptr cinfo)
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exit(99);
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}
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static int _gdImageJpegCtx(gdImagePtr im, gdIOCtx *outfile, int quality);
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/*
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* Write IM to OUTFILE as a JFIF-formatted JPEG image, using quality
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* QUALITY. If QUALITY is in the range 0-100, increasing values
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@ -231,8 +233,11 @@ BGD_DECLARE(void *) gdImageJpegPtr(gdImagePtr im, int *size, int quality)
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void *rv;
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gdIOCtx *out = gdNewDynamicCtx(2048, NULL);
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if (out == NULL) return NULL;
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gdImageJpegCtx(im, out, quality);
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rv = gdDPExtractData(out, size);
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if (!_gdImageJpegCtx(im, out, quality)) {
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rv = gdDPExtractData(out, size);
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} else {
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rv = NULL;
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}
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out->gd_free(out);
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return rv;
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}
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@ -253,6 +258,12 @@ void jpeg_gdIOCtx_dest(j_compress_ptr cinfo, gdIOCtx *outfile);
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*/
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BGD_DECLARE(void) gdImageJpegCtx(gdImagePtr im, gdIOCtx *outfile, int quality)
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{
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_gdImageJpegCtx(im, outfile, quality);
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}
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/* returns 0 on success, 1 on failure */
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static int _gdImageJpegCtx(gdImagePtr im, gdIOCtx *outfile, int quality)
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{
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struct jpeg_compress_struct cinfo;
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struct jpeg_error_mgr jerr;
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@ -287,7 +298,7 @@ BGD_DECLARE(void) gdImageJpegCtx(gdImagePtr im, gdIOCtx *outfile, int quality)
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if(row) {
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gdFree(row);
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}
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return;
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return 1;
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}
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cinfo.err->emit_message = jpeg_emit_message;
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@ -328,7 +339,7 @@ BGD_DECLARE(void) gdImageJpegCtx(gdImagePtr im, gdIOCtx *outfile, int quality)
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if(row == 0) {
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gd_error("gd-jpeg: error: unable to allocate JPEG row structure: gdCalloc returns NULL\n");
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jpeg_destroy_compress(&cinfo);
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return;
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return 1;
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}
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rowptr[0] = row;
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@ -405,6 +416,7 @@ BGD_DECLARE(void) gdImageJpegCtx(gdImagePtr im, gdIOCtx *outfile, int quality)
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jpeg_finish_compress(&cinfo);
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jpeg_destroy_compress(&cinfo);
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gdFree(row);
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return 0;
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}
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@ -88,6 +88,8 @@ int gd_getin(void *in)
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return (gdGetC((gdIOCtx *)in));
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}
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static int _gdImageWBMPCtx(gdImagePtr image, int fg, gdIOCtx *out);
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/*
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Function: gdImageWBMPCtx
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@ -100,6 +102,12 @@ int gd_getin(void *in)
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out - the stream where to write
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*/
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BGD_DECLARE(void) gdImageWBMPCtx(gdImagePtr image, int fg, gdIOCtx *out)
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{
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_gdImageWBMPCtx(image, fg, out);
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}
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/* returns 0 on success, 1 on failure */
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static int _gdImageWBMPCtx(gdImagePtr image, int fg, gdIOCtx *out)
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{
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int x, y, pos;
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Wbmp *wbmp;
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@ -107,7 +115,7 @@ BGD_DECLARE(void) gdImageWBMPCtx(gdImagePtr image, int fg, gdIOCtx *out)
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/* create the WBMP */
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if((wbmp = createwbmp(gdImageSX(image), gdImageSY(image), WBMP_WHITE)) == NULL) {
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gd_error("Could not create WBMP\n");
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return;
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return 1;
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}
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/* fill up the WBMP structure */
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@ -123,11 +131,15 @@ BGD_DECLARE(void) gdImageWBMPCtx(gdImagePtr image, int fg, gdIOCtx *out)
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/* write the WBMP to a gd file descriptor */
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if(writewbmp(wbmp, &gd_putout, out)) {
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freewbmp(wbmp);
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gd_error("Could not save WBMP\n");
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return 1;
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}
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/* des submitted this bugfix: gdFree the memory. */
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freewbmp(wbmp);
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return 0;
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}
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/*
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@ -271,8 +283,11 @@ BGD_DECLARE(void *) gdImageWBMPPtr(gdImagePtr im, int *size, int fg)
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void *rv;
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gdIOCtx *out = gdNewDynamicCtx(2048, NULL);
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if (out == NULL) return NULL;
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gdImageWBMPCtx(im, fg, out);
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rv = gdDPExtractData(out, size);
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if (!_gdImageWBMPCtx(im, fg, out)) {
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rv = gdDPExtractData(out, size);
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} else {
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rv = NULL;
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}
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out->gd_free(out);
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return rv;
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}
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@ -3,5 +3,6 @@
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/jpeg_empty_file
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/jpeg_im2im
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/jpeg_null
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/jpeg_ptr_double_free
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/jpeg_read
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/jpeg_resolution
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@ -2,6 +2,7 @@ IF(JPEG_FOUND)
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LIST(APPEND TESTS_FILES
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jpeg_empty_file
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jpeg_im2im
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jpeg_ptr_double_free
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jpeg_null
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)
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@ -2,7 +2,8 @@ if HAVE_LIBJPEG
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libgd_test_programs += \
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jpeg/jpeg_empty_file \
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jpeg/jpeg_im2im \
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jpeg/jpeg_null
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jpeg/jpeg_null \
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jpeg/jpeg_ptr_double_free
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if HAVE_LIBPNG
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libgd_test_programs += \
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@ -0,0 +1,31 @@
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/**
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* Test that failure to convert to JPEG returns NULL
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*
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* We are creating an image, set its width to zero, and pass this image to
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* `gdImageJpegPtr()` which is supposed to fail, and as such should return NULL.
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*
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* See also <https://github.com/libgd/libgd/issues/381>
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*/
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#include "gd.h"
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#include "gdtest.h"
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int main()
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{
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gdImagePtr src, dst;
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int size;
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src = gdImageCreateTrueColor(1, 10);
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gdTestAssert(src != NULL);
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src->sx = 0; /* this hack forces gdImageJpegPtr() to fail */
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dst = gdImageJpegPtr(src, &size, 0);
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gdTestAssert(dst == NULL);
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gdImageDestroy(src);
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return gdNumFailures();
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}
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