[PATCH 5/7] wrlib: Improved file format detection

[Christophe]

From: Christophe CURIS <christophe.cu...@free.fr>

- remove header not needed anymore
- revert change for XPM to stay in line with the standard
- changed PNG to stuck to the standard
- increased GIF to the complete signature

Signed-off-by: Christophe CURIS <christophe.cu...@free.fr>
---
 wrlib/load.c | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/wrlib/load.c b/wrlib/load.c
index fe5cc1e..73b2d95 100644
--- a/wrlib/load.c
+++ b/wrlib/load.c
@@ -33,10 +33,6 @@
 #include <time.h>
 #include <assert.h>
 
-#ifdef USE_PNG
-#include <png.h>
-#endif
-
 #include "wraster.h"
 #include "imgformat.h"
 
@@ -281,7 +277,7 @@ char *RGetImageFileFormat(const char *file)
 static WRImgFormat identFile(const char *path)
 {
        FILE *file;
-       unsigned char buffer[7];
+       unsigned char buffer[32];
        size_t nread;
 
        assert(path != NULL);
@@ -301,7 +297,7 @@ static WRImgFormat identFile(const char *path)
        RETRY( fclose(file) )
 
        /* check for XPM */
-       if (strncmp((char *)buffer, "/* XPM", 6) == 0)
+       if (strncmp((char *)buffer, "/* XPM */", 9) == 0)
                return IM_XPM;
 
        /* check for TIFF */
@@ -309,8 +305,15 @@ static WRImgFormat identFile(const char *path)
            || (buffer[0] == 'M' && buffer[1] == 'M' && buffer[2] == 0 && 
buffer[3] == '*'))
                return IM_TIFF;
 
-       /* check for PNG */
-       if (buffer[0] == 0x89 && buffer[1] == 'P' && buffer[2] == 'N' && 
buffer[3] == 'G')
+       /*
+        * check for PNG
+        *
+        * The signature is defined in the PNG specifiation:
+        * http://www.libpng.org/pub/png/spec/1.2/PNG-Structure.html
+        * it is valid for v1.0, v1.1, v1.2 and ISO version
+        */
+       if (buffer[0] == 137 && buffer[1] == 80 && buffer[2] == 78 && buffer[3] 
== 71 &&
+           buffer[4] ==  13 && buffer[5] == 10 && buffer[6] == 26 && buffer[7] 
== 10)
                return IM_PNG;
 
        /* check for PBM or PGM or PPM */
@@ -322,7 +325,8 @@ static WRImgFormat identFile(const char *path)
                return IM_JPEG;
 
        /* check for GIF */
-       if (buffer[0] == 'G' && buffer[1] == 'I' && buffer[2] == 'F' && 
buffer[3] == '8')
+       if (buffer[0] == 'G' && buffer[1] == 'I' && buffer[2] == 'F' && 
buffer[3] == '8' &&
+           (buffer[4] == '7' ||  buffer[4] == '9') && buffer[5] == 'a')
                return IM_GIF;
 
        return IM_UNKNOWN;
-- 
1.9.1


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