128 lines
3.5 KiB
C
128 lines
3.5 KiB
C
/*
|
|
* 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 1.7 1997/03/18 19:37:17 mpp 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;
|
|
char *s;
|
|
char nbuf[HOWMANY+1]; /* one extra for terminating '\0' */
|
|
char *token;
|
|
register 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 - 1; i++) {
|
|
if (!isascii(buf[i]) ||
|
|
(iscntrl(buf[i]) && !isspace(buf[i]) &&
|
|
buf[i] != '\b' && buf[i] != '\032' && buf[i] != '\033'
|
|
)
|
|
)
|
|
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 = strcpy(nbuf, buf);
|
|
has_escapes = (strchr(s, '\033') != NULL);
|
|
while ((token = strtok(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;
|
|
}
|
|
|
|
|