backup.c

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/*
   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_dir_len;
extern unsigned int backup_dir_remainder;
extern char backup_dir_buf[MAXPATHLEN];
extern char *backup_suffix;
extern char *backup_dir;

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;

/* make a complete pathname for backup file */
char *get_backup_name(char *fname)
{
        if (backup_dir) {
                if (stringjoin(backup_dir_buf + backup_dir_len, backup_dir_remainder,
                               fname, backup_suffix, NULL) < backup_dir_remainder)
                        return backup_dir_buf;
        } else {
                if (stringjoin(backup_dir_buf, MAXPATHLEN,
                               fname, backup_suffix, NULL) < MAXPATHLEN)
                        return backup_dir_buf;
        }

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

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

        if (!fnamebak)
                return 0;

        while (1) {
                if (do_rename(fname, fnamebak) == 0) {
                        if (verbose > 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
****************************************************************************/
static int make_bak_dir(char *fullpath)
{
        STRUCT_STAT st;
        char *rel = fullpath + backup_dir_len;
        char *end = rel + strlen(rel);
        char *p = end;

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

        /* Try to find an existing dir, starting from the deepest dir. */
        while (1) {
                if (--p == fullpath) {
                        p += strlen(p);
                        goto failure;
                }
                if (*p == '/') {
                        *p = '\0';
                        if (mkdir_defmode(fullpath) == 0)
                                break;
                        if (errno != ENOENT) {
                                rsyserr(FERROR, errno,
                                        "make_bak_dir mkdir %s failed",
                                        full_fname(fullpath));
                                goto failure;
                        }
                }
        }

        /* Make all the dirs that we didn't find on the way here. */
        while (1) {
                if (p >= rel) {
                        /* Try to transfer the directory settings of the
                         * actual dir that the files are coming from. */
                        if (do_stat(rel, &st) < 0) {
                                rsyserr(FERROR, errno,
                                        "make_bak_dir stat %s failed",
                                        full_fname(rel));
                        } else {
                                do_lchown(fullpath, st.st_uid, st.st_gid);
                                do_chmod(fullpath, st.st_mode);
#ifdef SUPPORT_ACLS
                                if (preserve_acls)
                                        dup_acl(end, fullpath, st.st_mode);
#endif
#ifdef SUPPORT_XATTRS
                                if (preserve_xattrs)
                                        dup_xattr(end, fullpath );
#endif
                        }
                }
                *p = '/';
                p += strlen(p);
                if (p == end)
                        break;
                if (mkdir_defmode(fullpath) < 0) {
                        rsyserr(FERROR, errno, "make_bak_dir mkdir %s failed",
                                full_fname(fullpath));
                        goto failure;
                }
        }
        return 0;

  failure:
        while (p != end) {
                *p = '/';
                p += strlen(p);
        }
        return -1;
}

/* robustly move a file, creating new directory structures if necessary */
static int robust_move(char *src, char *dst)
{
        if (robust_rename(src, dst, NULL, 0755) < 0
         && (errno != ENOENT || make_bak_dir(dst) < 0
          || robust_rename(src, dst, NULL, 0755) < 0))
                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(char *fname)
{
        STRUCT_STAT st;
        struct file_struct *file;
        char *buf;
        int kept = 0;
        int ret_code;

        /* return if no file to keep */
        if (do_lstat(fname, &st) < 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)))
                return 0;

#ifdef SUPPORT_ACLS
        if (preserve_acls)
                push_keep_backup_acl(file, fname, buf);
#endif
#ifdef SUPPORT_XATTRS
        if (preserve_xattrs)
                push_keep_backup_xattr(file, fname, buf);
#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))) {
                do_unlink(buf);
                if (do_mknod(buf, file->mode, file->u.rdev) < 0
                    && (errno != ENOENT || make_bak_dir(buf) < 0
                     || do_mknod(buf, file->mode, file->u.rdev) < 0)) {
                        rsyserr(FERROR, errno, "mknod %s failed",
                                full_fname(buf));
                } else if (verbose > 2) {
                        rprintf(FINFO, "make_backup: DEVICE %s successful.\n",
                                fname);
                }
                kept = 1;
                do_unlink(fname);
        }

        if (!kept && S_ISDIR(file->mode)) {
                /* make an empty directory */
                if (do_mkdir(buf, file->mode) < 0
                    && (errno != ENOENT || make_bak_dir(buf) < 0
                     || do_mkdir(buf, file->mode) < 0)) {
                        rsyserr(FINFO, errno, "mkdir %s failed",
                                full_fname(buf));
                }

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

#ifdef SUPPORT_LINKS
        if (!kept && preserve_links && S_ISLNK(file->mode)) {
                if (safe_symlinks && unsafe_symlink(file->u.link, buf)) {
                        if (verbose) {
                                rprintf(FINFO, "ignoring unsafe symlink %s -> %s\n",
                                        full_fname(buf), file->u.link);
                        }
                        kept = 1;
                } else {
                        do_unlink(buf);
                        if (do_symlink(file->u.link, buf) < 0
                            && (errno != ENOENT || make_bak_dir(buf) < 0
                             || do_symlink(file->u.link, buf) < 0)) {
                                rsyserr(FERROR, errno, "link %s -> \"%s\"",
                                        full_fname(buf),
                                        file->u.link);
                        }
                        do_unlink(fname);
                        kept = 1;
                }
        }
#endif

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

        /* move to keep tree if a file */
        if (!kept) {
                if (robust_move(fname, buf) != 0) {
                        rsyserr(FERROR, errno, "keep_backup failed: %s -> \"%s\"",
                                full_fname(fname), buf);
                } else if (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... */
                }
        }
        set_file_attrs(buf, file, NULL, 0);
#ifdef SUPPORT_ACLS
        if (preserve_acls)
                cleanup_keep_backup_acl();
#endif
#ifdef SUPPORT_XATTRS
        if (preserve_xattrs)
                cleanup_keep_backup_xattr();
#endif
        free(file);

        if (verbose > 1) {
                rprintf(FINFO, "backed up %s to %s\n",
                        fname, buf);
        }
        return 1;
}


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

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