1 |
edhill |
1.1 |
/* (C) Copyright 1993,1994 by Carnegie Mellon University |
2 |
|
|
* All Rights Reserved. |
3 |
|
|
* |
4 |
|
|
* Permission to use, copy, modify, distribute, and sell this software |
5 |
|
|
* and its documentation for any purpose is hereby granted without |
6 |
|
|
* fee, provided that the above copyright notice appear in all copies |
7 |
|
|
* and that both that copyright notice and this permission notice |
8 |
|
|
* appear in supporting documentation, and that the name of Carnegie |
9 |
|
|
* Mellon University not be used in advertising or publicity |
10 |
|
|
* pertaining to distribution of the software without specific, |
11 |
|
|
* written prior permission. Carnegie Mellon University makes no |
12 |
|
|
* representations about the suitability of this software for any |
13 |
|
|
* purpose. It is provided "as is" without express or implied |
14 |
|
|
* warranty. |
15 |
|
|
* |
16 |
|
|
* CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO |
17 |
|
|
* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY |
18 |
|
|
* AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE |
19 |
|
|
* FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
20 |
|
|
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN |
21 |
|
|
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING |
22 |
|
|
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS |
23 |
|
|
* SOFTWARE. |
24 |
|
|
*/ |
25 |
|
|
#include <stdio.h> |
26 |
jmc |
1.4 |
#include <string.h> |
27 |
edhill |
1.1 |
|
28 |
|
|
/* Description of the various file formats and their magic numbers */ |
29 |
|
|
struct magic { |
30 |
|
|
char *name; /* Name of the file format */ |
31 |
|
|
char *num; /* The magic number */ |
32 |
|
|
int len; /* Length of same (0 means strlen(magicnum)) */ |
33 |
|
|
}; |
34 |
|
|
|
35 |
|
|
/* The magic numbers of the file formats we know about */ |
36 |
|
|
static struct magic magic[] = { |
37 |
|
|
{ "image/gif", "GIF", 0 }, |
38 |
|
|
{ "image/jpeg", "\377\330\377", 0 }, |
39 |
|
|
{ "video/mpeg", "\0\0\001\263", 4 }, |
40 |
|
|
{ "application/postscript", "%!", 0 }, |
41 |
|
|
}; |
42 |
|
|
static int num_magic = (sizeof(magic)/sizeof(magic[0])); |
43 |
|
|
static char *default_type = "application/octet-stream"; |
44 |
|
|
|
45 |
|
|
/* The longest magic number */ |
46 |
|
|
static int max_magiclen = 0; |
47 |
|
|
|
48 |
|
|
/* |
49 |
|
|
* Determins the format of the file "inputf". The name |
50 |
|
|
* of the file format (or NULL on error) is returned. |
51 |
|
|
*/ |
52 |
|
|
char *magic_look(FILE *infile) |
53 |
|
|
{ |
54 |
|
|
int i, j; |
55 |
|
|
char buf[80]; |
56 |
|
|
int numread = 0; |
57 |
|
|
|
58 |
|
|
if (max_magiclen == 0) { |
59 |
|
|
for (i=0; i<num_magic; i++) { |
60 |
|
|
if (magic[i].len == 0) magic[i].len = strlen(magic[i].num); |
61 |
|
|
if (magic[i].len > max_magiclen) max_magiclen = magic[i].len; |
62 |
|
|
} |
63 |
|
|
} |
64 |
|
|
|
65 |
|
|
numread = fread(buf, 1, max_magiclen, infile); |
66 |
|
|
rewind(infile); |
67 |
|
|
|
68 |
|
|
for (i=0; i<num_magic; i++) { |
69 |
|
|
if (numread >= magic[i].len) { |
70 |
|
|
for (j=0; j<magic[i].len; j++) { |
71 |
|
|
if (buf[j] != magic[i].num[j]) break; |
72 |
|
|
} |
73 |
|
|
if (j == magic[i].len) return magic[i].name; |
74 |
|
|
} |
75 |
|
|
} |
76 |
|
|
|
77 |
|
|
return default_type; |
78 |
|
|
} |