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/*
* Ascii magic -- file types that we know based on keywords
* that can appear anywhere in the file.
*
* Copyright (c) Ian F. Darwin, 1987.
* Written by Ian F. Darwin.
*
* This software is not subject to any license of the American Telephone
* and Telegraph Company or of the Regents of the University of California.
*
* Permission is granted to anyone to use this software for any purpose on
* any computer system, and to alter it and redistribute it freely, subject
* to the following restrictions:
*
* 1. The author is not responsible for the consequences of use of this
* software, no matter how awful, even if they arise from flaws in it.
*
* 2. The origin of this software must not be misrepresented, either by
* explicit claim or by omission. Since few users ever read sources,
* credits must appear in the documentation.
*
* 3. Altered versions must be plainly marked as such, and must not be
* misrepresented as being the original software. Since few users
* ever read sources, credits must appear in the documentation.
*
* 4. This notice may not be removed or altered.
*/
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#include <unistd.h>
#include "file.h"
#include "names.h"
#ifndef lint
static char *moduleid =
"@(#)$Id: ascmagic.c,v 1.17 1994/01/21 01:25:30 christos Exp $";
#endif /* lint */
/* an optimisation over plain strcmp() */
#define STREQ(a, b) (*(a) == *(b) && strcmp((a), (b)) == 0)
int
ascmagic(buf, nbytes)
unsigned char *buf;
int nbytes; /* size actually read */
{
int i, isblock, has_escapes = 0;
unsigned char *s;
char nbuf[HOWMANY+1]; /* one extra for terminating '\0' */
char *token;
register struct names *p;
/* these are easy, do them first */
/*
* for troff, look for . + letter + letter or .\";
* this must be done to disambiguate tar archives' ./file
* and other trash from real troff input.
*/
if (*buf == '.') {
unsigned char *tp = buf + 1;
while (isascii(*tp) && isspace(*tp))
++tp; /* skip leading whitespace */
if ((isascii(*tp) && (isalnum(*tp) || *tp=='\\') &&
isascii(*(tp+1)) && (isalnum(*(tp+1)) || *tp=='"'))) {
ckfputs("troff or preprocessor input text", stdout);
return 1;
}
}
if ((*buf == 'c' || *buf == 'C') &&
isascii(*(buf + 1)) && isspace(*(buf + 1))) {
ckfputs("fortran program text", stdout);
return 1;
}
/* look for tokens from names.h - this is expensive! */
/* make a copy of the buffer here because strtok() will destroy it */
s = (unsigned char*) memcpy(nbuf, buf, nbytes);
s[nbytes] = '\0';
has_escapes = (memchr(s, '\033', nbytes) != NULL);
while ((token = strtok((char*)s, " \t\n\r\f")) != NULL) {
s = NULL; /* make strtok() keep on tokin' */
for (p = names; p < names + NNAMES; p++) {
if (STREQ(p->name, token)) {
ckfputs(types[p->type], stdout);
if (has_escapes)
ckfputs(" (with escape sequences)",
stdout);
return 1;
}
}
}
switch (is_tar(buf, nbytes)) {
case 1:
ckfputs("tar archive", stdout);
return 1;
case 2:
ckfputs("POSIX tar archive", stdout);
return 1;
}
for (i = 0; i < nbytes; i++) {
if (!isascii(*(buf+i)))
return 0; /* not all ascii */
}
/* all else fails, but it is ascii... */
ckfputs("ascii text", stdout);
if (has_escapes) {
ckfputs(" (with escape sequences)", stdout);
}
return 1;
}
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