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/* $OpenBSD: ascmagic.c,v 1.6 2003/03/11 21:26:26 ian Exp $ */
/*
* ASCII magic -- file types that we know based on keywords
* that can appear anywhere in the file.
*
* Copyright (c) Ian F. Darwin 1986-1995.
* Software written by Ian F. Darwin and others;
* maintained 1995-present by Christos Zoulas and others.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice immediately at the beginning of the file, without modification,
* this list of conditions, and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Ian F. Darwin and others.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#include <unistd.h>
#include <err.h>
#include "file.h"
#include "names.h"
#ifndef lint
static char *moduleid = "$OpenBSD: ascmagic.c,v 1.6 2003/03/11 21:26:26 ian 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, has_escapes = 0;
unsigned char *s;
char nbuf[HOWMANY+1]; /* one extra for terminating '\0' */
char *token;
struct names *p;
/*
* Do the tar test first, because if the first file in the tar
* archive starts with a dot, we can confuse it with an nroff file.
*/
switch (is_tar(buf, nbytes)) {
case 1:
ckfputs("tar archive", stdout);
return 1;
case 2:
ckfputs("POSIX tar archive", stdout);
return 1;
}
/*
* 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[1] == '"'))) {
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;
}
/* Make sure we are dealing with ascii text before looking for tokens */
for (i = 0; i < nbytes; i++) {
if (!isascii(buf[i]))
return 0; /* not all ASCII */
}
/* 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;
}
}
}
/* 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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