HardenedBSD/contrib/file/magic.c
2007-05-24 16:12:23 +00:00

410 lines
9.1 KiB
C

/*
* Copyright (c) Christos Zoulas 2003.
* All Rights Reserved.
*
* 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.
*
* 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 "file.h"
#include "magic.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/param.h> /* for MAXPATHLEN */
#include <sys/stat.h>
#ifdef QUICK
#include <sys/mman.h>
#endif
#include <limits.h> /* for PIPE_BUF */
#if defined(HAVE_UTIMES)
# include <sys/time.h>
#elif defined(HAVE_UTIME)
# if defined(HAVE_SYS_UTIME_H)
# include <sys/utime.h>
# elif defined(HAVE_UTIME_H)
# include <utime.h>
# endif
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h> /* for read() */
#endif
#ifdef HAVE_LOCALE_H
#include <locale.h>
#endif
#include <netinet/in.h> /* for byte swapping */
#include "patchlevel.h"
#ifndef lint
FILE_RCSID("@(#)$Id: magic.c,v 1.35 2006/10/31 19:37:17 christos Exp $")
#endif /* lint */
#ifdef __EMX__
private char *apptypeName = NULL;
protected int file_os2_apptype(struct magic_set *ms, const char *fn,
const void *buf, size_t nb);
#endif /* __EMX__ */
private void free_mlist(struct mlist *);
private void close_and_restore(const struct magic_set *, const char *, int,
const struct stat *);
private int info_from_stat(struct magic_set *, mode_t);
#ifndef STDIN_FILENO
#define STDIN_FILENO 0
#endif
public struct magic_set *
magic_open(int flags)
{
struct magic_set *ms;
if ((ms = malloc(sizeof(struct magic_set))) == NULL)
return NULL;
if (magic_setflags(ms, flags) == -1) {
errno = EINVAL;
goto free1;
}
ms->o.ptr = ms->o.buf = malloc(ms->o.size = 1024);
if (ms->o.buf == NULL)
goto free1;
ms->o.pbuf = malloc(ms->o.psize = 1024);
if (ms->o.pbuf == NULL)
goto free2;
ms->c.off = malloc((ms->c.len = 10) * sizeof(*ms->c.off));
if (ms->c.off == NULL)
goto free3;
ms->o.len = 0;
ms->haderr = 0;
ms->error = -1;
ms->mlist = NULL;
return ms;
free3:
free(ms->o.pbuf);
free2:
free(ms->o.buf);
free1:
free(ms);
return NULL;
}
private void
free_mlist(struct mlist *mlist)
{
struct mlist *ml;
if (mlist == NULL)
return;
for (ml = mlist->next; ml != mlist;) {
struct mlist *next = ml->next;
struct magic *mg = ml->magic;
file_delmagic(mg, ml->mapped, ml->nmagic);
free(ml);
ml = next;
}
free(ml);
}
private int
info_from_stat(struct magic_set *ms, mode_t md)
{
/* We cannot open it, but we were able to stat it. */
if (md & 0222)
if (file_printf(ms, "writable, ") == -1)
return -1;
if (md & 0111)
if (file_printf(ms, "executable, ") == -1)
return -1;
if (S_ISREG(md))
if (file_printf(ms, "regular file, ") == -1)
return -1;
if (file_printf(ms, "no read permission") == -1)
return -1;
return 0;
}
public void
magic_close(struct magic_set *ms)
{
free_mlist(ms->mlist);
free(ms->o.pbuf);
free(ms->o.buf);
free(ms->c.off);
free(ms);
}
/*
* load a magic file
*/
public int
magic_load(struct magic_set *ms, const char *magicfile)
{
struct mlist *ml = file_apprentice(ms, magicfile, FILE_LOAD);
if (ml) {
free_mlist(ms->mlist);
ms->mlist = ml;
return 0;
}
return -1;
}
public int
magic_compile(struct magic_set *ms, const char *magicfile)
{
struct mlist *ml = file_apprentice(ms, magicfile, FILE_COMPILE);
free_mlist(ml);
return ml ? 0 : -1;
}
public int
magic_check(struct magic_set *ms, const char *magicfile)
{
struct mlist *ml = file_apprentice(ms, magicfile, FILE_CHECK);
free_mlist(ml);
return ml ? 0 : -1;
}
private void
close_and_restore(const struct magic_set *ms, const char *name, int fd,
const struct stat *sb)
{
if (fd == STDIN_FILENO)
return;
(void) close(fd);
if ((ms->flags & MAGIC_PRESERVE_ATIME) != 0) {
/*
* Try to restore access, modification times if read it.
* This is really *bad* because it will modify the status
* time of the file... And of course this will affect
* backup programs
*/
#ifdef HAVE_UTIMES
struct timeval utsbuf[2];
utsbuf[0].tv_sec = sb->st_atime;
utsbuf[1].tv_sec = sb->st_mtime;
(void) utimes(name, utsbuf); /* don't care if loses */
#elif defined(HAVE_UTIME_H) || defined(HAVE_SYS_UTIME_H)
struct utimbuf utbuf;
utbuf.actime = sb->st_atime;
utbuf.modtime = sb->st_mtime;
(void) utime(name, &utbuf); /* don't care if loses */
#endif
}
}
#ifndef COMPILE_ONLY
/*
* find type of named file
*/
public const char *
magic_file(struct magic_set *ms, const char *inname)
{
int fd = 0;
int rv = -1;
unsigned char *buf;
struct stat sb;
ssize_t nbytes = 0; /* number of bytes read from a datafile */
int ispipe = 0;
/*
* one extra for terminating '\0', and
* some overlapping space for matches near EOF
*/
#define SLOP (1 + sizeof(union VALUETYPE))
if ((buf = malloc(HOWMANY + SLOP)) == NULL)
return NULL;
if (file_reset(ms) == -1)
goto done;
switch (file_fsmagic(ms, inname, &sb)) {
case -1: /* error */
goto done;
case 0: /* nothing found */
break;
default: /* matched it and printed type */
rv = 0;
goto done;
}
if (inname == NULL) {
fd = STDIN_FILENO;
if (fstat(fd, &sb) == 0 && S_ISFIFO(sb.st_mode))
ispipe = 1;
} else {
int flags = O_RDONLY|O_BINARY;
if (stat(inname, &sb) == 0 && S_ISFIFO(sb.st_mode)) {
flags |= O_NONBLOCK;
ispipe = 1;
}
errno = 0;
if ((fd = open(inname, flags)) < 0) {
#ifdef __CYGWIN__
char *tmp = alloca(strlen(inname) + 5);
(void)strcat(strcpy(tmp, inname), ".exe");
if ((fd = open(tmp, flags)) < 0) {
#endif
if (info_from_stat(ms, sb.st_mode) == -1)
goto done;
rv = 0;
goto done;
#ifdef __CYGWIN__
}
#endif
}
#ifdef O_NONBLOCK
if ((flags = fcntl(fd, F_GETFL)) != -1) {
flags &= ~O_NONBLOCK;
(void)fcntl(fd, F_SETFL, flags);
}
#endif
}
/*
* try looking at the first HOWMANY bytes
*/
if (ispipe) {
ssize_t r = 0;
while ((r = sread(fd, (void *)&buf[nbytes],
(size_t)(HOWMANY - nbytes))) > 0) {
nbytes += r;
if (r < PIPE_BUF) break;
}
if (nbytes == 0) {
/* We can not read it, but we were able to stat it. */
if (info_from_stat(ms, sb.st_mode) == -1)
goto done;
rv = 0;
goto done;
}
} else {
if ((nbytes = read(fd, (char *)buf, HOWMANY)) == -1) {
file_error(ms, errno, "cannot read `%s'", inname);
goto done;
}
}
if (nbytes == 0) {
if (file_printf(ms, (ms->flags & MAGIC_MIME) ?
"application/x-empty" : "empty") == -1)
goto done;
} else if (nbytes == 1) {
if (file_printf(ms, "very short file (no magic)") == -1)
goto done;
} else {
(void)memset(buf + nbytes, 0, SLOP); /* NUL terminate */
#ifdef __EMX__
switch (file_os2_apptype(ms, inname, buf, nbytes)) {
case -1:
goto done;
case 0:
break;
default:
rv = 0;
goto done;
}
#endif
if (file_buffer(ms, fd, buf, (size_t)nbytes) == -1)
goto done;
#ifdef BUILTIN_ELF
if (nbytes > 5) {
/*
* We matched something in the file, so this *might*
* be an ELF file, and the file is at least 5 bytes
* long, so if it's an ELF file it has at least one
* byte past the ELF magic number - try extracting
* information from the ELF headers that cannot easily
* be extracted with rules in the magic file.
*/
file_tryelf(ms, fd, buf, (size_t)nbytes);
}
#endif
}
rv = 0;
done:
free(buf);
close_and_restore(ms, inname, fd, &sb);
return rv == 0 ? file_getbuffer(ms) : NULL;
}
public const char *
magic_buffer(struct magic_set *ms, const void *buf, size_t nb)
{
if (file_reset(ms) == -1)
return NULL;
/*
* The main work is done here!
* We have the file name and/or the data buffer to be identified.
*/
if (file_buffer(ms, -1, buf, nb) == -1) {
return NULL;
}
return file_getbuffer(ms);
}
#endif
public const char *
magic_error(struct magic_set *ms)
{
return ms->haderr ? ms->o.buf : NULL;
}
public int
magic_errno(struct magic_set *ms)
{
return ms->haderr ? ms->error : 0;
}
public int
magic_setflags(struct magic_set *ms, int flags)
{
#if !defined(HAVE_UTIME) && !defined(HAVE_UTIMES)
if (flags & MAGIC_PRESERVE_ATIME)
return -1;
#endif
ms->flags = flags;
return 0;
}