check_if_png: clarify comments.

Before this patch check_if_png() comment was kind of misleading because
it talked about the behaviour of png_sig_cmp() which isn't the same as
check_if_png().
This commit is contained in:
Alexandre Perrin 2016-07-14 16:04:26 +02:00
parent e8005d43c6
commit 09cc95b989
2 changed files with 11 additions and 4 deletions

View file

@ -146,8 +146,8 @@ fail:
/* hacked from https://dev.w3.org/Amaya/libpng/example.c /* hacked from https://dev.w3.org/Amaya/libpng/example.c
* *
* Check to see if a file is a PNG file using png_sig_cmp(). png_sig_cmp() * Check if a file is a PNG image using png_sig_cmp(). Returns 1 if the given
* returns zero if the image is a PNG and nonzero if it isn't a PNG. * file is a PNG and 0 otherwise.
*/ */
#define PNG_BYTES_TO_CHECK 4 #define PNG_BYTES_TO_CHECK 4
int check_if_png(const char *filename) int check_if_png(const char *filename)
@ -164,7 +164,11 @@ int check_if_png(const char *filename)
if (fread(buf, 1, PNG_BYTES_TO_CHECK, infile) != PNG_BYTES_TO_CHECK) if (fread(buf, 1, PNG_BYTES_TO_CHECK, infile) != PNG_BYTES_TO_CHECK)
goto out; goto out;
/* Compare the first PNG_BYTES_TO_CHECK bytes of the signature. */ /*
* Compare the first PNG_BYTES_TO_CHECK bytes of the signature.
* png_sig_cmp() returns zero if the image is a PNG and nonzero if it
* isn't a PNG.
*/
if (png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK) == 0) if (png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK) == 0)
ret = 1; ret = 1;

View file

@ -32,7 +32,10 @@ void dump_cells(const struct quirc_code *code);
*/ */
int load_jpeg(struct quirc *q, const char *filename); int load_jpeg(struct quirc *q, const char *filename);
/* check if a file is a PNG image. */ /* Check if a file is a PNG image.
*
* returns 1 if the given file is a PNG and 0 otherwise.
*/
int check_if_png(const char *filename); int check_if_png(const char *filename);
/* Read a PNG image into the decoder. /* Read a PNG image into the decoder.