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file: more sanity checking for tga image detection to avoid false positives

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This commit is contained in:
cinap_lenrek 2013-01-21 12:01:05 +01:00
parent e18b9f6fd2
commit c4d7f17916
1 changed files with 19 additions and 6 deletions
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25
sys/src/cmd/file.c
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@ -1205,15 +1205,28 @@ istga(void)
uchar *p;
p = buf;
if(nbuf < 14)
if(nbuf < 18)
return 0;
if((p[12] | p[13]<<8) == 0) /* width */
return 0;
if((p[14] | p[15]<<8) == 0) /* height */
return 0;
if(p[16] != 8 && p[16] != 16 && p[16] != 24 && p[16] != 32) /* bpp */
return 0;
if(((p[2]|(1<<3)) & (~3)) != (1<<3)) /* rle flag */
return 0;
if(p[1] == 0 && ((p[2]&3) != 2 && (p[2]&3) != 3)) /* non color-mapped */
return 0;
if(p[1] == 1 && ((p[2]&3) != 1 || p[7] == 0)) /* color-mapped */
return 0;
if(p[16] != 8 && p[16] != 16 && p[16] != 24 && p[16] != 32) /* bpp */
if(p[1] == 0){ /* non color-mapped */
if((p[2]&3) != 2 && (p[2]&3) != 3)
return 0;
if((p[5] | p[6]<<8) != 0) /* palette length */
return 0;
} else
if(p[1] == 1){ /* color-mapped */
if((p[2]&3) != 1 || p[7] == 0)
return 0;
if((p[5] | p[6]<<8) == 0) /* palette length */
return 0;
} else
return 0;
print("%s\n", mime ? "image/tga" : "targa image");
return 1;