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Improved the backup code:
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- Backups do not interfere with an atomic update (when possible).
- Backing up a file will remove a directory that is in the way
  and visa versa.
- Unify the backup-dir and non-backup-dir code in backup.c.
- Improved the backup tests a little bit.
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Wayne Davison committed Jan 3, 2009
1 parent b3bf9b9 commit 21cddef
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Showing 7 changed files with 129 additions and 114 deletions.
177 changes: 84 additions & 93 deletions backup.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -51,43 +51,6 @@ char *get_backup_name(const char *fname)
return NULL;
}

/* simple backup creates a backup with a suffix in the same directory */
static int make_simple_backup(const char *fname)
{
int rename_errno;
const char *fnamebak = get_backup_name(fname);

if (!fnamebak)
return 0;

while (1) {
if (do_rename(fname, fnamebak) == 0) {
if (INFO_GTE(BACKUP, 1)) {
rprintf(FINFO, "backed up %s to %s\n",
fname, fnamebak);
}
break;
}
/* cygwin (at least version b19) reports EINVAL */
if (errno == ENOENT || errno == EINVAL)
break;

rename_errno = errno;
if (errno == EISDIR && do_rmdir(fnamebak) == 0)
continue;
if (errno == ENOTDIR && do_unlink(fnamebak) == 0)
continue;

rsyserr(FERROR, rename_errno, "rename %s to backup %s",
fname, fnamebak);
errno = rename_errno;
return 0;
}

return 1;
}


/****************************************************************************
Create a directory given an absolute path, perms based upon another directory
path
Expand Down Expand Up @@ -172,50 +135,87 @@ int make_bak_dir(const char *fullpath)
return 0;
}

/* robustly move a file, creating new directory structures if necessary */
static int robust_move(const char *src, char *dst)
/* 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)
{
if (robust_rename(src, dst, NULL, 0755) < 0) {
int save_errno = errno ? errno : EINVAL; /* 0 paranoia */
if (errno == ENOENT && make_bak_dir(dst) == 0) {
if (robust_rename(src, dst, NULL, 0755) < 0)
save_errno = errno ? errno : save_errno;
else
save_errno = 0;
}
if (save_errno) {
errno = save_errno;
return -1;
if (S_ISLNK(stp->st_mode)) {
if (prefer_rename)
goto do_rename;
#ifndef CAN_HARDLINK_SYMLINK
return 0; /* Use copy code. */
#endif
}
if (IS_SPECIAL(stp->st_mode) || IS_DEVICE(stp->st_mode)) {
if (prefer_rename)
goto do_rename;
#ifndef CAN_HARDLINK_SPECIAL
return 0; /* Use copy code. */
#endif
}
#ifdef SUPPORT_HARD_LINKS
if (!S_ISDIR(stp->st_mode)) {
if (do_link(from, to) == 0)
return 2;
return 0;
}
#endif
do_rename:
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(to); /* Just in case... */
}
return 1;
}
return 0;
}


/* 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(const char *fname)
/* Hard-link, rename, or copy an item to the backup name. Returns 2 if item
* was duplicated into backup area, 1 if item was moved, or 0 for failure.*/
int make_backup(const char *fname, BOOL prefer_rename)
{
stat_x sx;
struct file_struct *file;
char *buf;
int save_preserve_xattrs = preserve_xattrs;
int kept = 0;
int ret_code;
int save_preserve_xattrs;
char *buf = get_backup_name(fname);
int ret = 0;

if (!buf)
return 0;

init_stat_x(&sx);
/* Return success if no file to keep. */
if (x_lstat(fname, &sx.st, NULL) < 0)
return 1;

if (!(file = make_file(fname, NULL, NULL, 0, NO_FILTERS)))
return 1; /* the file could have disappeared */

if (!(buf = get_backup_name(fname))) {
unmake_file(file);
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) {
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;
} else if (backup_dir && errno == ENOENT) {
/* If the backup dir is missing, try again after making it. */
if (make_bak_dir(buf) != 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 1; /* the file could have disappeared */

#ifdef SUPPORT_ACLS
if (preserve_acls && !S_ISLNK(file->mode)) {
get_acl(fname, &sx);
Expand All @@ -235,7 +235,6 @@ static int keep_backup(const char *fname)
if ((am_root && preserve_devices && IS_DEVICE(file->mode))
|| (preserve_specials && IS_SPECIAL(file->mode))) {
int save_errno;
do_unlink(buf);
if (do_mknod(buf, file->mode, sx.st.st_rdev) < 0) {
save_errno = errno ? errno : EINVAL; /* 0 paranoia */
if (errno == ENOENT && make_bak_dir(buf) == 0) {
Expand All @@ -254,11 +253,11 @@ static int keep_backup(const char *fname)
rprintf(FINFO, "make_backup: DEVICE %s successful.\n",
fname);
}
kept = 1;
do_unlink(fname);
ret = 2;
}

if (!kept && S_ISDIR(file->mode)) {
if (!ret && S_ISDIR(file->mode)) {
int ret_code;
/* make an empty directory */
if (do_mkdir(buf, file->mode) < 0) {
int save_errno = errno ? errno : EINVAL; /* 0 paranoia */
Expand All @@ -279,20 +278,19 @@ static int keep_backup(const char *fname)
rprintf(FINFO, "make_backup: RMDIR %s returns %i\n",
full_fname(fname), ret_code);
}
kept = 1;
ret = 2;
}

#ifdef SUPPORT_LINKS
if (!kept && preserve_links && S_ISLNK(file->mode)) {
if (!ret && preserve_links && S_ISLNK(file->mode)) {
const char *sl = F_SYMLINK(file);
if (safe_symlinks && unsafe_symlink(sl, buf)) {
if (INFO_GTE(SYMSAFE, 1)) {
rprintf(FINFO, "ignoring unsafe symlink %s -> %s\n",
full_fname(buf), sl);
}
kept = 1;
ret = 2;
} else {
do_unlink(buf);
if (do_symlink(sl, buf) < 0) {
int save_errno = errno ? errno : EINVAL; /* 0 paranoia */
if (errno == ENOENT && make_bak_dir(buf) == 0) {
Expand All @@ -306,47 +304,40 @@ static int keep_backup(const char *fname)
full_fname(buf), sl);
}
}
do_unlink(fname);
kept = 1;
ret = 2;
}
}
#endif

if (!kept && !S_ISREG(file->mode)) {
if (!ret && !S_ISREG(file->mode)) {
rprintf(FINFO, "make_bak: skipping non-regular file %s\n",
fname);
unmake_file(file);
return 1;
return 2;
}

/* move to keep tree if a file */
if (!kept) {
if (robust_move(fname, buf) != 0) {
/* Copy to backup tree if a file. */
if (!ret) {
if (copy_file(fname, buf, -1, file->mode, 1) < 0) {
rsyserr(FERROR, errno, "keep_backup failed: %s -> \"%s\"",
full_fname(fname), buf);
} else if (sx.st.st_nlink > 1) {
/* If someone has hard-linked the file into the backup
* dir, rename() might return success but do nothing! */
robust_unlink(fname); /* Just in case... */
unmake_file(file);
return 0;
}
ret = 2;
}

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

unmake_file(file);

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


/* main backup switch routine */
int make_backup(const char *fname)
{
if (backup_dir)
return keep_backup(fname);
return make_simple_backup(fname);
return ret;
}
34 changes: 28 additions & 6 deletions delete.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -169,12 +169,18 @@ enum delret delete_item(char *fbuf, uint16 mode, uint16 flags)
if (S_ISDIR(mode)) {
what = "rmdir";
ok = do_rmdir(fbuf) == 0;
} else if (make_backups > 0 && (backup_dir || !is_backup_file(fbuf))) {
what = "make_backup";
ok = make_backup(fbuf);
} else {
what = "unlink";
ok = robust_unlink(fbuf) == 0;
if (make_backups > 0 && (backup_dir || !is_backup_file(fbuf))) {
what = "make_backup";
ok = make_backup(fbuf, True);
if (ok == 2) {
what = "unlink";
ok = robust_unlink(fbuf) == 0;
}
} else {
what = "unlink";
ok = robust_unlink(fbuf) == 0;
}
}

if (ok) {
Expand Down Expand Up @@ -219,8 +225,24 @@ enum delret delete_item(char *fbuf, uint16 mode, uint16 flags)
case DEL_FOR_SPECIAL: desc = "special file"; break;
default: exit_cleanup(RERR_UNSUPPORTED); /* IMPOSSIBLE */
}
rprintf(FERROR_XFER, "could not make way for new %s: %s\n",
rprintf(FERROR_XFER, "could not make way for %s %s: %s\n",
flags & DEL_FOR_BACKUP ? "backup" : "new",
desc, fbuf);
}
return ret;
}

uint16 get_del_for_flag(uint16 mode)
{
if (S_ISREG(mode))
return DEL_FOR_FILE;
if (S_ISDIR(mode))
return DEL_FOR_DIR;
if (S_ISLNK(mode))
return DEL_FOR_SYMLINK;
if (IS_DEVICE(mode))
return DEL_FOR_DEVICE;
if (IS_SPECIAL(mode))
return DEL_FOR_SPECIAL;
exit_cleanup(RERR_UNSUPPORTED); /* IMPOSSIBLE */
}
8 changes: 4 additions & 4 deletions hlink.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -217,6 +217,7 @@ static int maybe_hard_link(struct file_struct *file, int ndx,
const char *realname, int itemizing, enum logcode code)
{
if (statret == 0) {
int ok = 0;
if (sxp->st.st_dev == old_stp->st_dev
&& sxp->st.st_ino == old_stp->st_ino) {
if (itemizing) {
Expand All @@ -229,10 +230,9 @@ static int maybe_hard_link(struct file_struct *file, int ndx,
file->flags |= FLAG_HLINK_DONE;
return 0;
}
if (make_backups > 0) {
if (!make_backup(fname))
return -1;
} else if (robust_unlink(fname)) {
if (make_backups > 0 && (ok = make_backup(fname, True)) == 0)
return -1;
if (ok != 1 && robust_unlink(fname) && errno != ENOENT) {
rsyserr(FERROR_XFER, errno, "unlink %s failed",
full_fname(fname));
return -1;
Expand Down
2 changes: 1 addition & 1 deletion receiver.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -331,7 +331,7 @@ static void handle_delayed_updates(char *local_name)
struct file_struct *file = cur_flist->files[ndx];
fname = local_name ? local_name : f_name(file, NULL);
if ((partialptr = partial_dir_fname(fname)) != NULL) {
if (make_backups > 0 && !make_backup(fname))
if (make_backups > 0 && !make_backup(fname, False))
continue;
if (DEBUG_GTE(RECV, 1)) {
rprintf(FINFO, "renaming %s to %s\n",
Expand Down
5 changes: 3 additions & 2 deletions rsync.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -561,9 +561,10 @@ int finish_transfer(const char *fname, const char *fnametmp,
}

if (make_backups > 0 && overwriting_basis) {
if (!make_backup(fname))
int ok = make_backup(fname, False);
if (!ok)
return 1;
if (fnamecmp == fname)
if (ok == 1 && fnamecmp == fname)
fnamecmp = get_backup_name(fname);
}

Expand Down
1 change: 1 addition & 0 deletions rsync.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -249,6 +249,7 @@ enum msgcode {
#define DEL_FOR_SYMLINK (1<<5) /* making room for a replacement symlink */
#define DEL_FOR_DEVICE (1<<6) /* making room for a replacement device */
#define DEL_FOR_SPECIAL (1<<7) /* making room for a replacement special */
#define DEL_FOR_BACKUP (1<<8) /* the delete is for a backup operation */

#define DEL_MAKE_ROOM (DEL_FOR_FILE|DEL_FOR_DIR|DEL_FOR_SYMLINK|DEL_FOR_DEVICE|DEL_FOR_SPECIAL)

Expand Down
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