file.c

创建一个符合iso-9660标准的iso文件系统

/*
**	find file types by using a modified "magic" file
**
**	based on file v3.22 by Ian F. Darwin (see below)
**
**	For each entry in the magic file, the message MUST start with
**	two 4 character strings which are the CREATOR and TYPE for the
**	Mac file. Any continuation lines are ignored. e.g magic entry
**	for a GIF file:
**	
**	0       string          GIF8            8BIM GIFf
**	>4      string          7a              \b, version 8%s,
**	>4      string          9a              \b, version 8%s,
**	>6      leshort         >0              %hd x
**	>8      leshort         >0              %hd,
**	#>10    byte            &0x80           color mapped,
**	#>10    byte&0x07       =0x00           2 colors
**	#>10    byte&0x07       =0x01           4 colors
**	#>10    byte&0x07       =0x02           8 colors
**	#>10    byte&0x07       =0x03           16 colors
**	#>10    byte&0x07       =0x04           32 colors
**	#>10    byte&0x07       =0x05           64 colors
**	#>10    byte&0x07       =0x06           128 colors
**	#>10    byte&0x07       =0x07           256 colors
**
**	Just the "8BIM" "GIFf" will be used whatever the type GIF file
**	it is.
**
**	Modified for mkhybrid James Pearson 19/5/98
*/

/*
 * file - find type of a file or files - main program.
 *
 * 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.
 */
#ifndef	lint
static char *moduleid = 
	"@(#)$Id: file.c,v 1.38 1997/01/15 19:28:35 christos Exp $";
#endif	/* lint */

#include <mconfig.h>
#include <stdio.h>
#include <stdxlib.h>
#include <strdefs.h>
#include <sys/types.h>
#include <sys/param.h>	/* for MAXPATHLEN */
#include <sys/stat.h>
#include <fcntl.h>	/* for open() */
#if (__COHERENT__ >= 0x420)
# include <sys/utime.h>
#else
# ifdef USE_UTIMES
#  include <sys/time.h>
# else
#  include <utime.h>
# endif
#endif
#include <unistd.h>	/* for read() */

#include <netinet/in.h>		/* for byte swapping */

#include "patchlevel.h"
#include "file.h"

int 			/* Global command-line options 		*/
#ifdef DEBUG
	debug = 1, 	/* debugging 				*/
#else
	debug = 0, 	/* debugging 				*/
#endif /* DEBUG */
	lflag = 0,	/* follow Symlinks (BSD only) 		*/
	zflag = 0;	/* follow (uncompress) compressed files */

int			/* Misc globals				*/
	nmagic = 0;	/* number of valid magic[]s 		*/

struct  magic *magic;	/* array of magic entries		*/

char *magicfile;	/* where magic be found 		*/

char *progname;		/* used throughout 			*/
int lineno;		/* line number in the magic file	*/

char *	get_magic_match	__PR((const char *inname));
void	clean_magic	__PR((void));

#if 0
static int	byteconv4	__P((int, int, int));
static short	byteconv2	__P((int, int, int));
#endif

#if 0
/*
 * byteconv4
 * Input:
 *	from		4 byte quantity to convert
 *	same		whether to perform byte swapping
 *	big_endian	whether we are a big endian host
 */
static int
byteconv4(from, same, big_endian)
    int from;
    int same;
    int big_endian;
{
  if (same)
    return from;
  else if (big_endian)		/* lsb -> msb conversion on msb */
  {
    union {
      int i;
      char c[4];
    } retval, tmpval;

    tmpval.i = from;
    retval.c[0] = tmpval.c[3];
    retval.c[1] = tmpval.c[2];
    retval.c[2] = tmpval.c[1];
    retval.c[3] = tmpval.c[0];

    return retval.i;
  }
  else
    return ntohl(from);		/* msb -> lsb conversion on lsb */
}

/*
 * byteconv2
 * Same as byteconv4, but for shorts
 */
static short
byteconv2(from, same, big_endian)
	int from;
	int same;
	int big_endian;
{
  if (same)
    return from;
  else if (big_endian)		/* lsb -> msb conversion on msb */
  {
    union {
      short s;
      char c[2];
    } retval, tmpval;

    tmpval.s = (short) from;
    retval.c[0] = tmpval.c[1];
    retval.c[1] = tmpval.c[0];

    return retval.s;
  }
  else
    return ntohs(from);		/* msb -> lsb conversion on lsb */
}
#endif

/*
 * get_magic_match - get the CREATOR/TYPE string
 * based on the original process()
 */
char *
get_magic_match(inname)
const char	*inname;
{
	int	fd = 0;
	unsigned char	buf[HOWMANY+1];	/* one extra for terminating '\0' */
	struct stat	sb;
	int nbytes = 0;	/* number of bytes read from a datafile */
	char *match;

	/* check the file is regular and non-zero length */
	if (stat(inname, &sb) != 0)
		return 0;

	if (sb.st_size == 0 || ! S_ISREG(sb.st_mode))
		return 0;

	if ((fd = open(inname, O_RDONLY)) < 0)
		    return 0;

	/*
	 * try looking at the first HOWMANY bytes
	 */
	if ((nbytes = read(fd, (char *)buf, HOWMANY)) == -1)
		return 0;

	if (nbytes == 0)
		return 0;
	else {
		buf[nbytes++] = '\0';	/* null-terminate it */
		match = softmagic(buf, nbytes);
	}

#ifdef RESTORE_TIME
	/* really no point as we going to access the file later anyway */
	{
		/*
		 * Try to restore access, modification times if read it.
		 */
# ifdef USE_UTIMES
		struct timeval  utsbuf[2];
		utsbuf[0].tv_sec = sb.st_atime;
		utsbuf[1].tv_sec = sb.st_mtime;

		(void) utimes(inname, utsbuf); /* don't care if loses */
# else
		struct utimbuf  utbuf;

		utbuf.actime = sb.st_atime;
		utbuf.modtime = sb.st_mtime;
		(void) utime(inname, &utbuf); /* don't care if loses */
# endif
#endif
	(void) close(fd);

	return(match);
}

/*
 * clean_magic - deallocate memory used
 */
void
clean_magic()
{
	if (magic)
		free(magic);
}
	

#ifdef MAIN
main(argc, argv)
int	argc;
char	**argv;
{
	char	*ret;
	char	creator[5];
	char	type[5];

	if (argc < 3)
		exit(1);

	init_magic(argv[1]);

	ret = get_magic_match(argv[2]);

	if (!ret)
		ret = "unixTEXT";

	sscanf(ret, "%4s%4s", creator, type);

	creator[4] = type[4] = '\0';

	printf("%s %s\n", creator, type);


	exit(0);
}
#endif /* MAIN */