rsync/backup.c

/*
   Copyright (C) Andrew Tridgell 1999

   This program 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 2 of the License, or
   (at your option) any later version.

   This program 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 this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/* backup handling code */

#include "rsync.h"

extern int verbose;
extern int backup_suffix_len;
extern int backup_dir_len;
extern char *backup_suffix;
extern char *backup_dir;
extern struct file_struct **hlink_list;

extern int am_root;
extern int preserve_devices;
extern int preserve_links;
extern int preserve_hard_links;
extern int orig_umask;

/* simple backup creates a backup with a suffix in the same directory */
static int make_simple_backup(char *fname)
{
	char fnamebak[MAXPATHLEN];

	if (stringjoin(fnamebak, sizeof fnamebak, fname, backup_suffix, NULL)
	    >= sizeof fnamebak) {
		rprintf(FERROR, "backup filename too long\n");
		return 0;
	}

	if (do_rename(fname, fnamebak) != 0) {
		/* cygwin (at least version b19) reports EINVAL */
		if (errno != ENOENT && errno != EINVAL) {
			rsyserr(FERROR, errno, "rename %s to backup %s", fname, fnamebak);
			return 0;
		}
	} else if (verbose > 1) {
		rprintf(FINFO, "backed up %s to %s\n", fname, fnamebak);
	}
	return 1;
}


/* recursively make a directory path */
static int make_dir(char *name, int mask)
{
	char newdir [MAXPATHLEN];
	char *p, *d;

	/* copy pathname over, look for last '/' */
	for (p = d = newdir; *name; *d++ = *name++)
		if (*name == '/')
			p = d;
	if (p == newdir)
		return 0;
	*p = 0;

	/* make the new directory, if that fails then make its parent */
	while (do_mkdir(newdir, mask) != 0) {
		if (errno != ENOENT || !make_dir(newdir, mask))
			return 0;
	}

	return 1;
} /* make_dir */


/****************************************************************************
Create a directory given an absolute path, perms based upon another directory
path
****************************************************************************/
static int make_bak_dir(char *fname, char *bak_path)
{
	STRUCT_STAT st;
	STRUCT_STAT *st2;
	char fullpath[MAXPATHLEN];
	char *p;
	char *q;

	while(strncmp(bak_path, "./", 2) == 0) bak_path += 2;

	if (pathjoin(fullpath, sizeof fullpath, bak_path, fname)
	    >= sizeof fullpath) {
		rprintf(FERROR, "backup dirname too long\n");
		return 0;
	}
	p = fullpath;
	q = fullpath + strlen(bak_path);
	if (*q == '/')
		q++; /* Point past the middle '/' added by pathjoin(). */

	/* Make the directories */
	while ((p = strchr(p, '/')) != NULL) {
		*p = 0;
		if (do_lstat(fullpath, &st) != 0) {
			do_mkdir(fullpath, 0777 & ~orig_umask);
			if (p > q) {
				if (do_lstat(q, &st) != 0) {
					rprintf(FERROR, "make_bak_dir stat %s failed: %s\n",
						full_fname(fullpath), strerror(errno));
				} else {
					st2 = &st;
					set_modtime(fullpath, st2->st_mtime);
					if (do_lchown(fullpath, st2->st_uid, st2->st_gid) != 0) {
						rprintf(FERROR, "make_bak_dir chown %s failed: %s\n",
							full_fname(fullpath), strerror(errno));
					}
					if (do_chmod(fullpath, st2->st_mode) != 0) {
						rprintf(FERROR, "make_bak_dir failed to set permissions on %s: %s\n",
							full_fname(fullpath), strerror(errno));
					}
				}
			}
		}
		*p++ = '/';
	}
	return 0;
}

/* robustly move a file, creating new directory structures if necessary */
static int robust_move(char *src, char *dst)
{
	int keep_trying = 4;
	int keep_path_extfs = 0;
	int failed;

	while (keep_trying) {
		if (keep_path_extfs) {
			failed = copy_file(src, dst, 0755);
			if (!failed)
				do_unlink(src);
		} else
			failed = robust_rename(src, dst);

		if (failed) {
			if (verbose > 2) {
				rprintf(FERROR, "robust_move failed: %s(%d)\n",
					strerror(errno), errno);
			}
			switch (errno) {
			case EXDEV:	/* external filesystem */
				keep_path_extfs = 1;
				keep_trying--;
				break;
			case ENOENT:	/* no directory to write to */
				make_dir(dst, 0700);
				keep_trying--;
				break;
			default:
				keep_trying = 0;
				break;
			}
		} else
			keep_trying = 0;
	} /* while */
	return !failed;
} /* robust_move */


/* if we have a backup_dir, then we get here from make_backup().
   We will move the file to be deleted into a parallel directory tree */
static int keep_backup(char *fname)
{
	static int initialised;
	char keep_name[MAXPATHLEN];
	STRUCT_STAT st;
	struct file_struct *file;
	int kept = 0;
	int ret_code;

	if (!initialised) {
		if (backup_dir_len && backup_dir[backup_dir_len - 1] == '/')
			backup_dir[--backup_dir_len] = '\0';
		if (verbose > 0)
			rprintf(FINFO, "backup_dir is %s\n", backup_dir);
		initialised = 1;
	}

	/* return if no file to keep */
#if SUPPORT_LINKS
	if (do_lstat(fname, &st)) return 1;
#else
	if (do_stat(fname, &st)) return 1;
#endif

	file = make_file(fname, NO_EXCLUDES);

	/* the file could have disappeared */
	if (!file) return 1;

	/* make a complete pathname for backup file */
	if (stringjoin(keep_name, sizeof keep_name,
		       backup_dir, "/", fname, backup_suffix, NULL)
	    >= sizeof keep_name) {
		rprintf(FERROR, "keep_backup filename too long\n");
		return 0;
	}

#ifdef HAVE_MKNOD
	/* Check to see if this is a device file, or link */
	if (IS_DEVICE(file->mode)) {
		if (am_root && preserve_devices) {
			make_bak_dir(fname, backup_dir);
			if (do_mknod(keep_name, file->mode, file->u.rdev) != 0) {
				rprintf(FERROR, "mknod %s failed: %s\n",
					full_fname(keep_name), strerror(errno));
			} else if (verbose > 2) {
				rprintf(FINFO,
					"make_backup: DEVICE %s successful.\n",
					fname);
			}
		}
		kept = 1;
		do_unlink(fname);
	}
#endif

	if (!kept && S_ISDIR(file->mode)) {
		/* make an empty directory */
		make_bak_dir(fname, backup_dir);
		do_mkdir(keep_name, file->mode);
		ret_code = do_rmdir(fname);

		if (verbose > 2) {
			rprintf(FINFO, "make_backup: RMDIR %s returns %i\n",
				full_fname(fname), ret_code);
		}
		kept = 1;
	}

#if SUPPORT_LINKS
	if (!kept && preserve_links && S_ISLNK(file->mode)) {
		extern int safe_symlinks;
		if (safe_symlinks && unsafe_symlink(file->u.link, keep_name)) {
			if (verbose) {
				rprintf(FINFO, "ignoring unsafe symlink %s -> %s\n",
					full_fname(keep_name), file->u.link);
			}
			kept = 1;
		}
		make_bak_dir(fname, backup_dir);
		if (do_symlink(file->u.link, keep_name) != 0) {
			rprintf(FERROR, "link %s -> %s : %s\n",
				full_fname(keep_name), file->u.link, strerror(errno));
		}
		do_unlink(fname);
		kept = 1;
	}
#endif
	if (!kept && preserve_hard_links && file->link_u.links
	    && hlink_list[file->F_HLINDEX] != file) {
		if (verbose > 1)
			rprintf(FINFO, "%s is a hard link\n", f_name(file));
	}

	if (!kept && !S_ISREG(file->mode)) {
		rprintf(FINFO, "make_bak: skipping non-regular file %s\n",
			fname);
	}

	/* move to keep tree if a file */
	if (!kept) {
		if (!robust_move(fname, keep_name)) {
			rprintf(FERROR, "keep_backup failed: %s -> \"%s\": %s\n",
				full_fname(fname), keep_name, strerror(errno));
		}
	}
	set_perms(keep_name, file, NULL, 0);
	free_file(file, FREE_STRUCT);

	if (verbose > 1)
		rprintf(FINFO, "keep_backup %s -> %s\n", fname, keep_name);
	return 1;
} /* keep_backup */


/* main backup switch routine */
int make_backup(char *fname)
{
	if (backup_dir)
		return keep_backup(fname);
	return make_simple_backup(fname);
}