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PNG loader: Use mmap() during signature check

This commit is contained in:
Kim Woelders 2021-09-30 13:12:37 +02:00
parent df050d2dbc
commit 07deb8c893
1 changed files with 16 additions and 7 deletions
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23
src/modules/loaders/loader_png.c
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@ -1,5 +1,7 @@
#include "loader_common.h"
#include <png.h>
#include <sys/mman.h>
/* this is a quick sample png loader module... nice and small isn't it? */
@ -7,7 +9,6 @@
#define PNG_BYTES_TO_CHECK 4
typedef struct {
unsigned char buf[PNG_BYTES_TO_CHECK];
unsigned char **lines;
} ImLib_PNG_data;
@ -20,7 +21,8 @@ comment_free(ImlibImage * im, void *data)
int
load2(ImlibImage * im, int load_data)
{
int rc;
int rc, ok;
void *fdata;
png_uint_32 w32, h32;
char hasa;
png_structp png_ptr = NULL;
@ -33,13 +35,20 @@ load2(ImlibImage * im, int load_data)
rc = LOAD_FAIL;
pdata.lines = NULL;
if (fread(pdata.buf, 1, PNG_BYTES_TO_CHECK, im->fp) != PNG_BYTES_TO_CHECK)
goto quit;
if (im->fsize < PNG_BYTES_TO_CHECK)
return rc;
if (png_sig_cmp(pdata.buf, 0, PNG_BYTES_TO_CHECK))
goto quit;
fdata =
mmap(NULL, PNG_BYTES_TO_CHECK, PROT_READ, MAP_SHARED, fileno(im->fp), 0);
if (fdata == MAP_FAILED)
return rc;
rewind(im->fp);
ok = png_sig_cmp(fdata, 0, PNG_BYTES_TO_CHECK) == 0;
munmap(fdata, PNG_BYTES_TO_CHECK);
if (!ok)
return rc;
png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png_ptr)