diffarch.c

unix 下tar 执行程序的源代码

/* Diff files from a tar archive.
   Copyright (C) 1988 Free Software Foundation

This file is part of GNU Tar.

GNU Tar is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 1, or (at your option)
any later version.

GNU Tar is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Tar; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

/*
 * Diff files from a tar archive.
 *
 * Written 30 April 1987 by John Gilmore, ihnp4!hoptoad!gnu.
 *
 * @(#) diffarch.c 1.10 87/11/11 - gnu
 */

#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>

#ifdef BSD42
#include <sys/file.h>
#endif

#ifndef MSDOS
#include <sys/ioctl.h>
#if !defined(USG) || defined(HAVE_MTIO)
#include <sys/mtio.h>
#endif
#else
#include <fcntl.h>
#endif

#ifdef USG
#include <fcntl.h>
#endif

/* Some systems don't have these #define's -- we fake it here. */
#ifndef O_RDONLY
#define	O_RDONLY	0
#endif
#ifndef	O_NDELAY
#define	O_NDELAY	0
#endif

#ifndef S_IFLNK
#define lstat stat
#endif

extern int errno;			/* From libc.a */
extern char *valloc();			/* From libc.a */

#include "tar.h"
#include "port.h"
#include "rmt.h"

extern union record *head;		/* Points to current tape header */
extern struct stat hstat;		/* Stat struct corresponding */
extern int head_standard;		/* Tape header is in ANSI format */

extern void print_header();
extern void skip_file();
extern void skip_extended_headers();

extern FILE *msg_file;

int now_verifying = 0;		/* Are we verifying at the moment? */

int	diff_fd;		/* Descriptor of file we're diffing */

char	*diff_buf = 0;		/* Pointer to area for reading
					   file contents into */

char	*diff_dir;		/* Directory contents for LF_DUMPDIR */

int different = 0;

/*struct sp_array *sparsearray;
int 		sp_ar_size = 10;*/
/*
 * Initialize for a diff operation
 */
diff_init()
{

	/*NOSTRICT*/
	diff_buf = (char *) valloc((unsigned)blocksize);
	if (!diff_buf) {
		msg("could not allocate memory for diff buffer of %d bytes",
			blocksize);
		exit(EX_ARGSBAD);
	}
}

/*
 * Diff a file against the archive.
 */
void
diff_archive()
{
	register char *data;
	int check, namelen;
	int err;
	long offset;
	struct stat filestat;
	int compare_chunk();
	int compare_dir();
#ifndef __MSDOS__
	dev_t	dev;
	ino_t	ino;
#endif
	char *get_dir_contents();
	long from_oct();
	long lseek();

	errno = EPIPE;			/* FIXME, remove perrors */

	saverec(&head);			/* Make sure it sticks around */
	userec(head);			/* And go past it in the archive */
	decode_header(head, &hstat, &head_standard, 1);	/* Snarf fields */

	/* Print the record from 'head' and 'hstat' */
	if (f_verbose) {
		if(now_verifying)
			fprintf(msg_file,"Verify ");
		print_header();
	}

	switch (head->header.linkflag) {

	default:
		msg("Unknown file type '%c' for %s, diffed as normal file",
			head->header.linkflag, head->header.name);
		/* FALL THRU */

	case LF_OLDNORMAL:
	case LF_NORMAL:
	case LF_SPARSE:
	case LF_CONTIG:
		/*
		 * Appears to be a file.
		 * See if it's really a directory.
		 */
		namelen = strlen(head->header.name)-1;
		if (head->header.name[namelen] == '/')
			goto really_dir;

		
		if(do_stat(&filestat)) {
			if (head->header.isextended)
				skip_extended_headers();
			skip_file((long)hstat.st_size);
			different++;
			goto quit;
		}

		if ((filestat.st_mode & S_IFMT) != S_IFREG) {
			fprintf(msg_file, "%s: not a regular file\n",
				head->header.name);
			skip_file((long)hstat.st_size);
			different++;
			goto quit;
		}

		filestat.st_mode &= ~S_IFMT;
		if (filestat.st_mode != hstat.st_mode)
			sigh("mode");
		if (filestat.st_uid  != hstat.st_uid)
			sigh("uid");
		if (filestat.st_gid  != hstat.st_gid)
			sigh("gid");
		if (filestat.st_mtime != hstat.st_mtime)
			sigh("mod time");
		if (head->header.linkflag != LF_SPARSE &&
				filestat.st_size != hstat.st_size) {
			sigh("size");
			skip_file((long)hstat.st_size);
			goto quit;
		}

		diff_fd = open(head->header.name, O_NDELAY|O_RDONLY);
#ifdef __MSDOS__
                setmode(diff_fd, O_BINARY);
#endif
		if (diff_fd < 0 && !f_absolute_paths) {
			char tmpbuf[NAMSIZ+2];

			tmpbuf[0]='/';
			strcpy(&tmpbuf[1],head->header.name);
			diff_fd=open(tmpbuf, O_NDELAY|O_RDONLY);
		}
		if (diff_fd < 0) {
			msg_perror("cannot open %s",head->header.name);
			if (head->header.isextended)
				skip_extended_headers();
			skip_file((long)hstat.st_size);
			different++;
			goto quit;
		}
		/*
		 * Need to treat sparse files completely differently here.
		 */
		if (head->header.linkflag == LF_SPARSE)
			diff_sparse_files(hstat.st_size);
		else 
			wantbytes((long)(hstat.st_size),compare_chunk);

		check = close(diff_fd);
		if (check < 0)
			msg_perror("Error while closing %s",head->header.name);

	quit:
		break;

#ifndef __MSDOS__
	case LF_LINK:
		if(do_stat(&filestat))
			break;
		dev = filestat.st_dev;
		ino = filestat.st_ino;
		err = stat(head->header.linkname, &filestat);
		if (err < 0) {
			if (errno==ENOENT) {
				fprintf(msg_file, "%s: does not exist\n",head->header.name);
			} else {
				msg_perror("cannot stat file %s",head->header.name);
			}
			different++;
			break;
		}
		if(filestat.st_dev!=dev || filestat.st_ino!=ino) {
			fprintf(msg_file, "%s not linked to %s\n",head->header.name,head->header.linkname);
			break;
		}
		break;
#endif

#ifdef S_IFLNK
	case LF_SYMLINK:
	{
		char linkbuf[NAMSIZ+3];
		check = readlink(head->header.name, linkbuf,
				 (sizeof linkbuf)-1);
		
		if (check < 0) {
			if (errno == ENOENT) {
				fprintf(msg_file,
					"%s: no such file or directory\n",
					head->header.name);
			} else {
				msg_perror("cannot read link %s",head->header.name);
			}
			different++;
			break;
		}

		linkbuf[check] = '\0';	/* Null-terminate it */
		if (strncmp(head->header.linkname, linkbuf, check) != 0) {
			fprintf(msg_file, "%s: symlink differs\n",
				head->header.linkname);
			different++;
		}
	}
		break;
#endif

	case LF_CHR:
		hstat.st_mode |= S_IFCHR;
		goto check_node;

#ifdef S_IFBLK
	/* If local system doesn't support block devices, use default case */
	case LF_BLK:
		hstat.st_mode |= S_IFBLK;
		goto check_node;
#endif

#ifdef S_IFIFO
	/* If local system doesn't support FIFOs, use default case */
	case LF_FIFO:
		hstat.st_mode |= S_IFIFO;
		hstat.st_rdev = 0;		/* FIXME, do we need this? */
		goto check_node;
#endif

	check_node:
		/* FIXME, deal with umask */
		if(do_stat(&filestat))
			break;
		if(hstat.st_rdev != filestat.st_rdev) {
			fprintf(msg_file, "%s: device numbers changed\n", head->header.name);
			different++;
			break;
		}
		if(hstat.st_mode != filestat.st_mode) {
			fprintf(msg_file, "%s: mode or device-type changed\n", head->header.name);
			different++;
			break;
		}
		break;

	case LF_DUMPDIR:
		data=diff_dir=get_dir_contents(head->header.name,0);
		wantbytes((long)(hstat.st_size),compare_dir);
		free(data);
		/* FALL THROUGH */

	case LF_DIR:
		/* Check for trailing / */
		namelen = strlen(head->header.name)-1;
	really_dir:
		while (namelen && head->header.name[namelen] == '/')
			head->header.name[namelen--] = '\0';	/* Zap / */

		if(do_stat(&filestat))
			break;
		if((filestat.st_mode&S_IFMT)!=S_IFDIR) {
			fprintf(msg_file, "%s is no longer a directory\n",head->header.name);
			different++;
			break;
		}
		if((filestat.st_mode&~S_IFMT) != hstat.st_mode)
			sigh("mode");
		break;

	case LF_VOLHDR:
		break;

	case LF_MULTIVOL:
		namelen = strlen(head->header.name)-1;
		if (head->header.name[namelen] == '/')
			goto really_dir;

		if(do_stat(&filestat))
			break;