backup.c - external_rsync - Gitiles

 /*
  * Backup handling code.
  *
  * Copyright (C) 1999 Andrew Tridgell
  * Copyright (C) 2003-2020 Wayne Davison
  *
  * 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 3 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, visit the http://fsf.org website.
  */

 #include "rsync.h"
 #include "ifuncs.h"

 extern int am_root;
 extern int preserve_acls;
 extern int preserve_xattrs;
 extern int preserve_devices;
 extern int preserve_specials;
 extern int preserve_links;
 extern int safe_symlinks;
 extern int backup_dir_len;
 extern unsigned int backup_dir_remainder;
 extern char backup_dir_buf[MAXPATHLEN];
 extern char *backup_suffix;
 extern char *backup_dir;

 /* Returns -1 on error, 0 on missing dir, and 1 on present dir. */
 static int validate_backup_dir(void)
 {
 	STRUCT_STAT st;

 	if (do_lstat(backup_dir_buf, &st) < 0) {
 		if (errno == ENOENT)
 			return 0;
 		rsyserr(FERROR, errno, "backup lstat %s failed", backup_dir_buf);
 		return -1;
 	}
 	if (!S_ISDIR(st.st_mode)) {
 		int flags = get_del_for_flag(st.st_mode) | DEL_FOR_BACKUP | DEL_RECURSE;
 		if (delete_item(backup_dir_buf, st.st_mode, flags) == 0)
 			return 0;
 		return -1;
 	}
 	return 1;
 }

 /* Create a backup path from the given fname, putting the result into
  * backup_dir_buf.  Any new directories (compared to the prior backup
  * path) are ensured to exist as directories, replacing anything else
  * that may be in the way (e.g. a symlink). */
 static BOOL copy_valid_path(const char *fname)
 {
 	const char *f;
 	int val;
 	BOOL ret = True;
 	stat_x sx;
 	char *b, *rel = backup_dir_buf + backup_dir_len, *name = rel;

 	for (f = fname, b = rel; *f && *f == *b; f++, b++) {
 		if (*b == '/')
 			name = b + 1;
 	}

 	if (stringjoin(rel, backup_dir_remainder, fname, backup_suffix, NULL) >= backup_dir_remainder) {
 		rprintf(FERROR, "backup filename too long\n");
 		*name = '\0';
 		return False;
 	}

 	for ( ; ; name = b + 1) {
 		if ((b = strchr(name, '/')) == NULL)
 			return True;
 		*b = '\0';

 		val = validate_backup_dir();
 		if (val == 0)
 			break;
 		if (val < 0) {
 			*name = '\0';
 			return False;
 		}

 		*b = '/';
 	}

 	init_stat_x(&sx);

 	for ( ; b; name = b + 1, b = strchr(name, '/')) {
 		*b = '\0';

 		while (do_mkdir(backup_dir_buf, ACCESSPERMS) < 0) {
 			if (errno == EEXIST) {
 				val = validate_backup_dir();
 				if (val > 0)
 					break;
 				if (val == 0)
 					continue;
 			} else
 				rsyserr(FERROR, errno, "backup mkdir %s failed", backup_dir_buf);
 			*name = '\0';
 			ret = False;
 			goto cleanup;
 		}

 		/* Try to transfer the directory settings of the actual dir
 		 * that the files are coming from. */
 		if (x_stat(rel, &sx.st, NULL) < 0)
 			rsyserr(FERROR, errno, "backup stat %s failed", full_fname(rel));
 		else {
 			struct file_struct *file;
 			if (!(file = make_file(rel, NULL, NULL, 0, NO_FILTERS)))
 				continue;
 #ifdef SUPPORT_ACLS
 			if (preserve_acls && !S_ISLNK(file->mode)) {
 				get_acl(rel, &sx);
 				cache_tmp_acl(file, &sx);
 				free_acl(&sx);
 			}
 #endif
 #ifdef SUPPORT_XATTRS
 			if (preserve_xattrs) {
 				get_xattr(rel, &sx);
 				cache_tmp_xattr(file, &sx);
 				free_xattr(&sx);
 			}
 #endif
 			set_file_attrs(backup_dir_buf, file, NULL, NULL, 0);
 			unmake_file(file);
 		}

 		*b = '/';
 	}

   cleanup:

 #ifdef SUPPORT_ACLS
 	uncache_tmp_acls();
 #endif
 #ifdef SUPPORT_XATTRS
 	uncache_tmp_xattrs();
 #endif

 	return ret;
 }

 /* Make a complete pathname for backup file and verify any new path elements. */
 char *get_backup_name(const char *fname)
 {
 	if (backup_dir) {
 		static int initialized = 0;
 		if (!initialized) {
 			int ret;
 			if (backup_dir_len > 1)
 				backup_dir_buf[backup_dir_len-1] = '\0';
 			ret = make_path(backup_dir_buf, 0);
 			if (backup_dir_len > 1)
 				backup_dir_buf[backup_dir_len-1] = '/';
 			if (ret < 0)
 				return NULL;
 			initialized = 1;
 		}
 		/* copy fname into backup_dir_buf while validating the dirs. */
 		if (copy_valid_path(fname))
 			return backup_dir_buf;
 		/* copy_valid_path() has printed an error message. */
 		return NULL;
 	}

 	if (stringjoin(backup_dir_buf, MAXPATHLEN, fname, backup_suffix, NULL) < MAXPATHLEN)
 		return backup_dir_buf;

 	rprintf(FERROR, "backup filename too long\n");
 	return NULL;
 }

 /* Has same return codes as make_backup(). */
 static inline int link_or_rename(const char *from, const char *to,
 				 BOOL prefer_rename, STRUCT_STAT *stp)
 {
 #ifdef SUPPORT_HARD_LINKS
 	if (!prefer_rename) {
 #ifndef CAN_HARDLINK_SYMLINK
 		if (S_ISLNK(stp->st_mode))
 			return 0; /* Use copy code. */
 #endif
 #ifndef CAN_HARDLINK_SPECIAL
 		if (IS_SPECIAL(stp->st_mode) || IS_DEVICE(stp->st_mode))
 			return 0; /* Use copy code. */
 #endif
 		if (do_link(from, to) == 0) {
 			if (DEBUG_GTE(BACKUP, 1))
 				rprintf(FINFO, "make_backup: HLINK %s successful.\n", from);
 			return 2;
 		}
 		/* We prefer to rename a regular file rather than copy it. */
 		if (!S_ISREG(stp->st_mode) || errno == EEXIST || errno == EISDIR)
 			return 0;
 	}
 #endif
 	if (do_rename(from, to) == 0) {
 		if (stp->st_nlink > 1 && !S_ISDIR(stp->st_mode)) {
 			/* If someone has hard-linked the file into the backup
 			 * dir, rename() might return success but do nothing! */
 			robust_unlink(from); /* Just in case... */
 		}
 		if (DEBUG_GTE(BACKUP, 1))
 			rprintf(FINFO, "make_backup: RENAME %s successful.\n", from);
 		return 1;
 	}
 	return 0;
 }

 /* Hard-link, rename, or copy an item to the backup name.  Returns 0 for
  * failure, 1 if item was moved, 2 if item was duplicated or hard linked
  * into backup area, or 3 if item doesn't exist or isn't a regular file. */
 int make_backup(const char *fname, BOOL prefer_rename)
 {
 	stat_x sx;
 	struct file_struct *file;
 	int save_preserve_xattrs;
 	char *buf;
 	int ret = 0;

 	init_stat_x(&sx);
 	/* Return success if no file to keep. */
 	if (x_lstat(fname, &sx.st, NULL) < 0)
 		return 3;

 	if (!(buf = get_backup_name(fname)))
 		return 0;

 	/* Try a hard-link or a rename first.  Using rename is not atomic, but
 	 * is more efficient than forcing a copy for larger files when no hard-
 	 * linking is possible. */
 	if ((ret = link_or_rename(fname, buf, prefer_rename, &sx.st)) != 0)
 		goto success;
 	if (errno == EEXIST || errno == EISDIR) {
 		STRUCT_STAT bakst;
 		if (do_lstat(buf, &bakst) == 0) {
 			int flags = get_del_for_flag(bakst.st_mode) | DEL_FOR_BACKUP | DEL_RECURSE;
 			if (delete_item(buf, bakst.st_mode, flags) != 0)
 				return 0;
 		}
 		if ((ret = link_or_rename(fname, buf, prefer_rename, &sx.st)) != 0)
 			goto success;
 	}

 	/* Fall back to making a copy. */
 	if (!(file = make_file(fname, NULL, &sx.st, 0, NO_FILTERS)))
 		return 3; /* the file could have disappeared */

 #ifdef SUPPORT_ACLS
 	if (preserve_acls && !S_ISLNK(file->mode)) {
 		get_acl(fname, &sx);
 		cache_tmp_acl(file, &sx);
 		free_acl(&sx);
 	}
 #endif
 #ifdef SUPPORT_XATTRS
 	if (preserve_xattrs) {
 		get_xattr(fname, &sx);
 		cache_tmp_xattr(file, &sx);
 		free_xattr(&sx);
 	}
 #endif

 	/* Check to see if this is a device file, or link */
 	if ((am_root && preserve_devices && IS_DEVICE(file->mode))
 	 || (preserve_specials && IS_SPECIAL(file->mode))) {
 		if (do_mknod(buf, file->mode, sx.st.st_rdev) < 0)
 			rsyserr(FERROR, errno, "mknod %s failed", full_fname(buf));
 		else if (DEBUG_GTE(BACKUP, 1))
 			rprintf(FINFO, "make_backup: DEVICE %s successful.\n", fname);
 		ret = 2;
 	}

 #ifdef SUPPORT_LINKS
 	if (!ret && preserve_links && S_ISLNK(file->mode)) {
 		const char *sl = F_SYMLINK(file);
 		if (safe_symlinks && unsafe_symlink(sl, fname)) {
 			if (INFO_GTE(SYMSAFE, 1)) {
 				rprintf(FINFO, "not backing up unsafe symlink \"%s\" -> \"%s\"\n",
 					fname, sl);
 			}
 			ret = 2;
 		} else {
 			if (do_symlink(sl, buf) < 0)
 				rsyserr(FERROR, errno, "link %s -> \"%s\"", full_fname(buf), sl);
 			else if (DEBUG_GTE(BACKUP, 1))
 				rprintf(FINFO, "make_backup: SYMLINK %s successful.\n", fname);
 			ret = 2;
 		}
 	}
 #endif

 	if (!ret && !S_ISREG(file->mode)) {
 		rprintf(FINFO, "make_bak: skipping non-regular file %s\n", fname);
 		unmake_file(file);
 #ifdef SUPPORT_ACLS
 		uncache_tmp_acls();
 #endif
 #ifdef SUPPORT_XATTRS
 		uncache_tmp_xattrs();
 #endif
 		return 3;
 	}

 	/* Copy to backup tree if a file. */
 	if (!ret) {
 		if (copy_file(fname, buf, -1, file->mode) < 0) {
 			rsyserr(FERROR, errno, "keep_backup failed: %s -> \"%s\"",
 				full_fname(fname), buf);
 			unmake_file(file);
 #ifdef SUPPORT_ACLS
 			uncache_tmp_acls();
 #endif
 #ifdef SUPPORT_XATTRS
 			uncache_tmp_xattrs();
 #endif
 			return 0;
 		}
 		if (DEBUG_GTE(BACKUP, 1))
 			rprintf(FINFO, "make_backup: COPY %s successful.\n", fname);
 		ret = 2;
 	}

 	save_preserve_xattrs = preserve_xattrs;
 	preserve_xattrs = 0;
 	set_file_attrs(buf, file, NULL, fname, ATTRS_ACCURATE_TIME);
 	preserve_xattrs = save_preserve_xattrs;

 	unmake_file(file);
 #ifdef SUPPORT_ACLS
 	uncache_tmp_acls();
 #endif
 #ifdef SUPPORT_XATTRS
 	uncache_tmp_xattrs();
 #endif

   success:
 	if (INFO_GTE(BACKUP, 1))
 		rprintf(FINFO, "backed up %s to %s\n", fname, buf);
 	return ret;
 }
	/*
	* Backup handling code.
	*
	* Copyright (C) 1999 Andrew Tridgell
	* Copyright (C) 2003-2020 Wayne Davison
	*
	* 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 3 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, visit the http://fsf.org website.
	*/

	#include "rsync.h"
	#include "ifuncs.h"

	extern int am_root;
	extern int preserve_acls;
	extern int preserve_xattrs;
	extern int preserve_devices;
	extern int preserve_specials;
	extern int preserve_links;
	extern int safe_symlinks;
	extern int backup_dir_len;
	extern unsigned int backup_dir_remainder;
	extern char backup_dir_buf[MAXPATHLEN];
	extern char *backup_suffix;
	extern char *backup_dir;

	/* Returns -1 on error, 0 on missing dir, and 1 on present dir. */
	static int validate_backup_dir(void)
	{
	STRUCT_STAT st;

	if (do_lstat(backup_dir_buf, &st) < 0) {
	if (errno == ENOENT)
	return 0;
	rsyserr(FERROR, errno, "backup lstat %s failed", backup_dir_buf);
	return -1;
	}
	if (!S_ISDIR(st.st_mode)) {
	int flags = get_del_for_flag(st.st_mode) \| DEL_FOR_BACKUP \| DEL_RECURSE;
	if (delete_item(backup_dir_buf, st.st_mode, flags) == 0)
	return 0;
	return -1;
	}
	return 1;
	}

	/* Create a backup path from the given fname, putting the result into
	* backup_dir_buf. Any new directories (compared to the prior backup
	* path) are ensured to exist as directories, replacing anything else
	* that may be in the way (e.g. a symlink). */
	static BOOL copy_valid_path(const char *fname)
	{
	const char *f;
	int val;
	BOOL ret = True;
	stat_x sx;
	char b, rel = backup_dir_buf + backup_dir_len, *name = rel;

	for (f = fname, b = rel; f && f == *b; f++, b++) {
	if (*b == '/')
	name = b + 1;
	}

	if (stringjoin(rel, backup_dir_remainder, fname, backup_suffix, NULL) >= backup_dir_remainder) {
	rprintf(FERROR, "backup filename too long\n");
	*name = '\0';
	return False;
	}

	for ( ; ; name = b + 1) {
	if ((b = strchr(name, '/')) == NULL)
	return True;
	*b = '\0';

	val = validate_backup_dir();
	if (val == 0)
	break;
	if (val < 0) {
	*name = '\0';
	return False;
	}

	*b = '/';
	}

	init_stat_x(&sx);

	for ( ; b; name = b + 1, b = strchr(name, '/')) {
	*b = '\0';

	while (do_mkdir(backup_dir_buf, ACCESSPERMS) < 0) {
	if (errno == EEXIST) {
	val = validate_backup_dir();
	if (val > 0)
	break;
	if (val == 0)
	continue;
	} else
	rsyserr(FERROR, errno, "backup mkdir %s failed", backup_dir_buf);
	*name = '\0';
	ret = False;
	goto cleanup;
	}

	/* Try to transfer the directory settings of the actual dir
	* that the files are coming from. */
	if (x_stat(rel, &sx.st, NULL) < 0)
	rsyserr(FERROR, errno, "backup stat %s failed", full_fname(rel));
	else {
	struct file_struct *file;
	if (!(file = make_file(rel, NULL, NULL, 0, NO_FILTERS)))
	continue;
	#ifdef SUPPORT_ACLS
	if (preserve_acls && !S_ISLNK(file->mode)) {
	get_acl(rel, &sx);
	cache_tmp_acl(file, &sx);
	free_acl(&sx);
	}
	#endif
	#ifdef SUPPORT_XATTRS
	if (preserve_xattrs) {
	get_xattr(rel, &sx);
	cache_tmp_xattr(file, &sx);
	free_xattr(&sx);
	}
	#endif
	set_file_attrs(backup_dir_buf, file, NULL, NULL, 0);
	unmake_file(file);
	}

	*b = '/';
	}

	cleanup:

	#ifdef SUPPORT_ACLS
	uncache_tmp_acls();
	#endif
	#ifdef SUPPORT_XATTRS
	uncache_tmp_xattrs();
	#endif

	return ret;
	}

	/* Make a complete pathname for backup file and verify any new path elements. */
	char get_backup_name(const char fname)
	{
	if (backup_dir) {
	static int initialized = 0;
	if (!initialized) {
	int ret;
	if (backup_dir_len > 1)
	backup_dir_buf[backup_dir_len-1] = '\0';
	ret = make_path(backup_dir_buf, 0);
	if (backup_dir_len > 1)
	backup_dir_buf[backup_dir_len-1] = '/';
	if (ret < 0)
	return NULL;
	initialized = 1;
	}
	/* copy fname into backup_dir_buf while validating the dirs. */
	if (copy_valid_path(fname))
	return backup_dir_buf;
	/* copy_valid_path() has printed an error message. */
	return NULL;
	}

	if (stringjoin(backup_dir_buf, MAXPATHLEN, fname, backup_suffix, NULL) < MAXPATHLEN)
	return backup_dir_buf;

	rprintf(FERROR, "backup filename too long\n");
	return NULL;
	}

	/* Has same return codes as make_backup(). */
	static inline int link_or_rename(const char from, const char to,
	BOOL prefer_rename, STRUCT_STAT *stp)
	{
	#ifdef SUPPORT_HARD_LINKS
	if (!prefer_rename) {
	#ifndef CAN_HARDLINK_SYMLINK
	if (S_ISLNK(stp->st_mode))
	return 0; /* Use copy code. */
	#endif
	#ifndef CAN_HARDLINK_SPECIAL
	if (IS_SPECIAL(stp->st_mode) \|\| IS_DEVICE(stp->st_mode))
	return 0; /* Use copy code. */
	#endif
	if (do_link(from, to) == 0) {
	if (DEBUG_GTE(BACKUP, 1))
	rprintf(FINFO, "make_backup: HLINK %s successful.\n", from);
	return 2;
	}
	/* We prefer to rename a regular file rather than copy it. */
	if (!S_ISREG(stp->st_mode) \|\| errno == EEXIST \|\| errno == EISDIR)
	return 0;
	}
	#endif
	if (do_rename(from, to) == 0) {
	if (stp->st_nlink > 1 && !S_ISDIR(stp->st_mode)) {
	/* If someone has hard-linked the file into the backup
	* dir, rename() might return success but do nothing! */
	robust_unlink(from); /* Just in case... */
	}
	if (DEBUG_GTE(BACKUP, 1))
	rprintf(FINFO, "make_backup: RENAME %s successful.\n", from);
	return 1;
	}
	return 0;
	}

	/* Hard-link, rename, or copy an item to the backup name. Returns 0 for
	* failure, 1 if item was moved, 2 if item was duplicated or hard linked
	* into backup area, or 3 if item doesn't exist or isn't a regular file. */
	int make_backup(const char *fname, BOOL prefer_rename)
	{
	stat_x sx;
	struct file_struct *file;
	int save_preserve_xattrs;
	char *buf;
	int ret = 0;

	init_stat_x(&sx);
	/* Return success if no file to keep. */
	if (x_lstat(fname, &sx.st, NULL) < 0)
	return 3;

	if (!(buf = get_backup_name(fname)))
	return 0;

	/* Try a hard-link or a rename first. Using rename is not atomic, but
	* is more efficient than forcing a copy for larger files when no hard-
	* linking is possible. */
	if ((ret = link_or_rename(fname, buf, prefer_rename, &sx.st)) != 0)
	goto success;
	if (errno == EEXIST \|\| errno == EISDIR) {
	STRUCT_STAT bakst;
	if (do_lstat(buf, &bakst) == 0) {
	int flags = get_del_for_flag(bakst.st_mode) \| DEL_FOR_BACKUP \| DEL_RECURSE;
	if (delete_item(buf, bakst.st_mode, flags) != 0)
	return 0;
	}
	if ((ret = link_or_rename(fname, buf, prefer_rename, &sx.st)) != 0)
	goto success;
	}

	/* Fall back to making a copy. */
	if (!(file = make_file(fname, NULL, &sx.st, 0, NO_FILTERS)))
	return 3; /* the file could have disappeared */

	#ifdef SUPPORT_ACLS
	if (preserve_acls && !S_ISLNK(file->mode)) {
	get_acl(fname, &sx);
	cache_tmp_acl(file, &sx);
	free_acl(&sx);
	}
	#endif
	#ifdef SUPPORT_XATTRS
	if (preserve_xattrs) {
	get_xattr(fname, &sx);
	cache_tmp_xattr(file, &sx);
	free_xattr(&sx);
	}
	#endif

	/* Check to see if this is a device file, or link */
	if ((am_root && preserve_devices && IS_DEVICE(file->mode))
	\|\| (preserve_specials && IS_SPECIAL(file->mode))) {
	if (do_mknod(buf, file->mode, sx.st.st_rdev) < 0)
	rsyserr(FERROR, errno, "mknod %s failed", full_fname(buf));
	else if (DEBUG_GTE(BACKUP, 1))
	rprintf(FINFO, "make_backup: DEVICE %s successful.\n", fname);
	ret = 2;
	}

	#ifdef SUPPORT_LINKS
	if (!ret && preserve_links && S_ISLNK(file->mode)) {
	const char *sl = F_SYMLINK(file);
	if (safe_symlinks && unsafe_symlink(sl, fname)) {
	if (INFO_GTE(SYMSAFE, 1)) {
	rprintf(FINFO, "not backing up unsafe symlink \"%s\" -> \"%s\"\n",
	fname, sl);
	}
	ret = 2;
	} else {
	if (do_symlink(sl, buf) < 0)
	rsyserr(FERROR, errno, "link %s -> \"%s\"", full_fname(buf), sl);
	else if (DEBUG_GTE(BACKUP, 1))
	rprintf(FINFO, "make_backup: SYMLINK %s successful.\n", fname);
	ret = 2;
	}
	}
	#endif

	if (!ret && !S_ISREG(file->mode)) {
	rprintf(FINFO, "make_bak: skipping non-regular file %s\n", fname);
	unmake_file(file);
	#ifdef SUPPORT_ACLS
	uncache_tmp_acls();
	#endif
	#ifdef SUPPORT_XATTRS
	uncache_tmp_xattrs();
	#endif
	return 3;
	}

	/* Copy to backup tree if a file. */
	if (!ret) {
	if (copy_file(fname, buf, -1, file->mode) < 0) {
	rsyserr(FERROR, errno, "keep_backup failed: %s -> \"%s\"",
	full_fname(fname), buf);
	unmake_file(file);
	#ifdef SUPPORT_ACLS
	uncache_tmp_acls();
	#endif
	#ifdef SUPPORT_XATTRS
	uncache_tmp_xattrs();
	#endif
	return 0;
	}
	if (DEBUG_GTE(BACKUP, 1))
	rprintf(FINFO, "make_backup: COPY %s successful.\n", fname);
	ret = 2;
	}

	save_preserve_xattrs = preserve_xattrs;
	preserve_xattrs = 0;
	set_file_attrs(buf, file, NULL, fname, ATTRS_ACCURATE_TIME);
	preserve_xattrs = save_preserve_xattrs;

	unmake_file(file);
	#ifdef SUPPORT_ACLS
	uncache_tmp_acls();
	#endif
	#ifdef SUPPORT_XATTRS
	uncache_tmp_xattrs();
	#endif

	success:
	if (INFO_GTE(BACKUP, 1))
	rprintf(FINFO, "backed up %s to %s\n", fname, buf);
	return ret;
	}