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/* (C) Copyright 1993,1994 by Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify, distribute, and sell this software
* and its documentation for any purpose is hereby granted without
* fee, provided that the above copyright notice appear in all copies
* and that both that copyright notice and this permission notice
* appear in supporting documentation, and that the name of Carnegie
* Mellon University not be used in advertising or publicity
* pertaining to distribution of the software without specific,
* written prior permission. Carnegie Mellon University makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied
* warranty.
*
* CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
* FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
* SOFTWARE.
*/
#include <stdio.h>
/* Description of the various file formats and their magic numbers */
struct magic {
char *name; /* Name of the file format */
char *num; /* The magic number */
int len; /* Length of same (0 means strlen(magicnum)) */
};
/* The magic numbers of the file formats we know about */
static struct magic magic[] = {
{ "image/gif", "GIF", 0 },
{ "image/jpeg", "\377\330\377", 0 },
{ "video/mpeg", "\0\0\001\263", 4 },
{ "application/postscript", "%!", 0 },
};
static int num_magic = (sizeof(magic)/sizeof(magic[0]));
static char *default_type = "application/octet-stream";
/* The longest magic number */
static int max_magiclen = 0;
/*
* Determins the format of the file "inputf". The name
* of the file format (or NULL on error) is returned.
*/
char *magic_look(infile)
FILE *infile;
{
int i, j;
char buf[80];
int numread = 0;
if (max_magiclen == 0) {
for (i=0; i<num_magic; i++) {
if (magic[i].len == 0) magic[i].len = strlen(magic[i].num);
if (magic[i].len > max_magiclen) max_magiclen = magic[i].len;
}
}
numread = fread(buf, 1, max_magiclen, infile);
rewind(infile);
for (i=0; i<num_magic; i++) {
if (numread >= magic[i].len) {
for (j=0; j<magic[i].len; j++) {
if (buf[j] != magic[i].num[j]) break;
}
if (j == magic[i].len) return magic[i].name;
}
}
return default_type;
}
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