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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: fsmagic.c,v 1.14 2009/10/27 23:59:37 deraadt Exp $ */
/*
 * 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.
 *  
 * 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.
 */
/*
 * fsmagic - magic based on filesystem info - directory, special files, etc.
 */

#include "file.h"
#include "magic.h"
#include <string.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <stdlib.h>
#include <sys/stat.h>
/* Since major is a function on SVR4, we cannot use `ifndef major'.  */
#ifdef MAJOR_IN_MKDEV
# include <sys/mkdev.h>
# define HAVE_MAJOR
#endif
#ifdef MAJOR_IN_SYSMACROS
# include <sys/sysmacros.h>
# define HAVE_MAJOR
#endif
#ifdef major			/* Might be defined in sys/types.h.  */
# define HAVE_MAJOR
#endif
  
#ifndef HAVE_MAJOR
# define major(dev)  (((dev) >> 8) & 0xff)
# define minor(dev)  ((dev) & 0xff)
#endif
#undef HAVE_MAJOR

private int
bad_link(struct magic_set *ms, int err, char *buf)
{
	char *errfmt;
	if (err == ELOOP)
		errfmt = "symbolic link in a loop";
	else
		errfmt = "broken symbolic link to `%s'";
	if (ms->flags & MAGIC_ERROR) {
		file_error(ms, err, errfmt, buf);
		return -1;
	} 
	if (file_printf(ms, errfmt, buf) == -1)
		return -1;
	return 1;
}

protected int
file_fsmagic(struct magic_set *ms, const char *fn, struct stat *sb)
{
	int ret = 0;
	int mime = ms->flags & MAGIC_MIME;
#ifdef	S_IFLNK
	char buf[BUFSIZ+4];
	int nch;
	struct stat tstatbuf;
#endif

	if (fn == NULL)
		return 0;

	/*
	 * Fstat is cheaper but fails for files you don't have read perms on.
	 * On 4.2BSD and similar systems, use lstat() to identify symlinks.
	 */
#ifdef	S_IFLNK
	if ((ms->flags & MAGIC_SYMLINK) == 0)
		ret = lstat(fn, sb);
	else
#endif
	ret = stat(fn, sb);	/* don't merge into if; see "ret =" above */

	if (ret) {
		if (ms->flags & MAGIC_ERROR) {
			file_error(ms, errno, "cannot stat `%s'", fn);
			return -1;
		}
		if (file_printf(ms, "cannot open `%s' (%s)",
		    fn, strerror(errno)) == -1)
			return -1;
		return 1;
	}

	if (mime) {
		if ((sb->st_mode & S_IFMT) != S_IFREG) {
			if ((mime & MAGIC_MIME_TYPE) &&
			    file_printf(ms, "application/x-not-regular-file")
			    == -1)
				    return -1;
			return 1;
		}
	}
	else {
#ifdef S_ISUID
		if (sb->st_mode & S_ISUID) 
			if (file_printf(ms, "setuid ") == -1)
				return -1;
#endif
#ifdef S_ISGID
		if (sb->st_mode & S_ISGID) 
			if (file_printf(ms, "setgid ") == -1)
				return -1;
#endif
#ifdef S_ISVTX
		if (sb->st_mode & S_ISVTX) 
			if (file_printf(ms, "sticky ") == -1)
				return -1;
#endif
	}
	
	switch (sb->st_mode & S_IFMT) {
	case S_IFDIR:
		if (file_printf(ms, "directory") == -1)
			return -1;
		return 1;
#ifdef S_IFCHR
	case S_IFCHR:
		/* 
		 * If -s has been specified, treat character special files
		 * like ordinary files.  Otherwise, just report that they
		 * are block special files and go on to the next file.
		 */
		if ((ms->flags & MAGIC_DEVICES) != 0)
			break;
#ifdef HAVE_STAT_ST_RDEV
# ifdef dv_unit
		if (file_printf(ms, "character special (%d/%d/%d)",
		    major(sb->st_rdev), dv_unit(sb->st_rdev),
		    dv_subunit(sb->st_rdev)) == -1)
			return -1;
# else
		if (file_printf(ms, "character special (%ld/%ld)",
		    (long) major(sb->st_rdev), (long) minor(sb->st_rdev)) == -1)
			return -1;
# endif
#else
		if (file_printf(ms, "character special") == -1)
			return -1;
#endif
		return 1;
#endif
#ifdef S_IFBLK
	case S_IFBLK:
		/* 
		 * If -s has been specified, treat block special files
		 * like ordinary files.  Otherwise, just report that they
		 * are block special files and go on to the next file.
		 */
		if ((ms->flags & MAGIC_DEVICES) != 0)
			break;
#ifdef HAVE_STAT_ST_RDEV
# ifdef dv_unit
		if (file_printf(ms, "block special (%d/%d/%d)",
		    major(sb->st_rdev), dv_unit(sb->st_rdev),
		    dv_subunit(sb->st_rdev)) == -1)
			return -1;
# else
		if (file_printf(ms, "block special (%ld/%ld)",
		    (long)major(sb->st_rdev), (long)minor(sb->st_rdev)) == -1)
			return -1;
# endif
#else
		if (file_printf(ms, "block special") == -1)
			return -1;
#endif
		return 1;
#endif
	/* TODO add code to handle V7 MUX and Blit MUX files */
#ifdef	S_IFIFO
	case S_IFIFO:
		if((ms->flags & MAGIC_DEVICES) != 0)
			break;
		if (file_printf(ms, "fifo (named pipe)") == -1)
			return -1;
		return 1;
#endif
#ifdef	S_IFDOOR
	case S_IFDOOR:
		if (file_printf(ms, "door") == -1)
			return -1;
		return 1;
#endif
#ifdef	S_IFLNK
	case S_IFLNK:
		if ((nch = readlink(fn, buf, BUFSIZ-1)) <= 0) {
			if (ms->flags & MAGIC_ERROR) {
			    file_error(ms, errno, "unreadable symlink `%s'",
				fn);
			    return -1;
			}
			if (file_printf(ms,
			    "unreadable symlink `%s' (%s)", fn,
			    strerror(errno)) == -1)
				return -1;
			return 1;
		}
		buf[nch] = '\0';	/* readlink(2) does not do this */

		/* If broken symlink, say so and quit early. */
		if (*buf == '/') {
			if (stat(buf, &tstatbuf) < 0)
				return bad_link(ms, errno, buf);
		} else {
			char *tmp;
			char buf2[BUFSIZ+BUFSIZ+4];

			if ((tmp = strrchr(fn,  '/')) == NULL) {
				tmp = buf; /* in current directory anyway */
			} else {
				if (tmp - fn + 1 > BUFSIZ) {
					if (ms->flags & MAGIC_ERROR) {
						file_error(ms, 0, 
						    "path too long: `%s'", buf);
						return -1;
					}
					if (file_printf(ms,
					    "path too long: `%s'", fn) == -1)
						return -1;
					return 1;
				}
				(void)strlcpy(buf2, fn, sizeof buf2);  /* take dir part */
				buf2[tmp - fn + 1] = '\0';
				(void)strlcat(buf2, buf, sizeof buf2); /* plus (rel) link */
				tmp = buf2;
			}
			if (stat(tmp, &tstatbuf) < 0)
				return bad_link(ms, errno, buf);
		}

		/* Otherwise, handle it. */
		if ((ms->flags & MAGIC_SYMLINK) != 0) {
			const char *p;
			ms->flags &= MAGIC_SYMLINK;
			p = magic_file(ms, buf);
			ms->flags |= MAGIC_SYMLINK;
			return p != NULL ? 1 : -1;
		} else { /* just print what it points to */
			if (file_printf(ms, "symbolic link to `%s'",
			    buf) == -1)
				return -1;
		}
	return 1;
#endif
#ifdef	S_IFSOCK
#ifndef __COHERENT__
	case S_IFSOCK:
		if (file_printf(ms, "socket") == -1)
			return -1;
		return 1;
#endif
#endif
	case S_IFREG:
		break;
	default:
		file_error(ms, 0, "invalid mode 0%o", sb->st_mode);
		return -1;
		/*NOTREACHED*/
	}

	/*
	 * regular file, check next possibility
	 *
	 * If stat() tells us the file has zero length, report here that
	 * the file is empty, so we can skip all the work of opening and 
	 * reading the file.
	 * But if the -s option has been given, we skip this optimization,
	 * since on some systems, stat() reports zero size for raw disk
	 * partitions.  (If the block special device really has zero length,
	 * the fact that it is empty will be detected and reported correctly
	 * when we read the file.)
	 */
	if ((ms->flags & MAGIC_DEVICES) == 0 && sb->st_size == 0) {
		if ((!mime || (mime & MAGIC_MIME_TYPE)) &&
		    file_printf(ms, mime ? "application/x-empty" :
		    "empty") == -1)
			return -1;
		return 1;
	}
	return 0;
}