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rcsid[] and sccsid[] and copyright[] are essentially unmaintained (and
unmaintainable).  these days, people use source.  these id's do not provide
any benefit, and do hurt the small install media
(the 33,000 line diff is essentially mechanical)
ok with the idea millert, ok dms

/* $OpenBSD: magic.c,v 1.8 2009/10/27 23:59:37 deraadt Exp $ */
/*
 * 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 <sys/types.h>
#include <sys/param.h>	/* for MAXPATHLEN */
#include <sys/stat.h>

#include "file.h"
#include "magic.h"

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.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 PIPE_BUF 
/* Get the PIPE_BUF from pathconf */
#ifdef _PC_PIPE_BUF
#define PIPE_BUF pathconf(".", _PC_PIPE_BUF)
#else
#define PIPE_BUF 512
#endif
#endif

#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 COMPILE_ONLY
private const char *file_or_fd(struct magic_set *, const char *, int);
#endif

#ifndef	STDIN_FILENO
#define	STDIN_FILENO	0
#endif

public struct magic_set *
magic_open(int flags)
{
	struct magic_set *ms;

	if ((ms = calloc((size_t)1, sizeof(struct magic_set))) == NULL)
		return NULL;

	if (magic_setflags(ms, flags) == -1) {
		errno = EINVAL;
		goto free;
	}

	ms->o.buf = ms->o.pbuf = NULL;

	ms->c.li = malloc((ms->c.len = 10) * sizeof(*ms->c.li));
	if (ms->c.li == NULL)
		goto free;
	
	ms->haderr = 0;
	ms->error = -1;
	ms->mlist = NULL;
	ms->file = "unknown";
	ms->line = 0;
	return ms;
free:
	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.li);
	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];
		(void)memset(utsbuf, 0, sizeof(utsbuf));
		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;

		(void)memset(utbuf, 0, sizeof(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 descriptor
 */
public const char *
magic_descriptor(struct magic_set *ms, int fd)
{
	return file_or_fd(ms, NULL, fd);
}

/*
 * find type of named file
 */
public const char *
magic_file(struct magic_set *ms, const char *inname)
{
	return file_or_fd(ms, inname, STDIN_FILENO);
}

private const char *
file_or_fd(struct magic_set *ms, const char *inname, int fd)
{
	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) {
		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__
			/* FIXME: Do this with EXEEXT from autotools */
			char *tmp = alloca(strlen(inname) + 5);
			(void)strcat(strcpy(tmp, inname), ".exe");
			if ((fd = open(tmp, flags)) < 0) {
#endif
				fprintf(stderr, "couldn't open file\n");
				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), 1)) > 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;
		}
	}

	(void)memset(buf + nbytes, 0, SLOP); /* NUL terminate */
	if (file_buffer(ms, fd, inname, buf, (size_t)nbytes) == -1)
		goto done;
	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, NULL, 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;
}