LXR busybox/libbb/copy

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * Mini copy_file implementation for busybox
   4 *
   5 * Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
   6 * SELinux support by Yuichi Nakamura <ynakam@hitachisoft.jp>
   7 *
   8 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   9 */
  10#include "libbb.h"
  11
  12// FEATURE_NON_POSIX_CP:
  13//
  14// POSIX: if exists and -i, ask (w/o -i assume yes).
  15// Then open w/o EXCL (yes, not unlink!).
  16// If open still fails and -f, try unlink, then try open again.
  17// Result: a mess:
  18// If dest is a (sym)link, we overwrite link destination!
  19// (or fail, if it points to dir/nonexistent location/etc).
  20// This is strange, but POSIX-correct.
  21// coreutils cp has --remove-destination to override this...
  22
  23/* Called if open of destination, link creation etc fails.
  24 * errno must be set to relevant value ("why we cannot create dest?")
  25 * to give reasonable error message */
  26static int ask_and_unlink(const char *dest, int flags)
  27{
  28        int e = errno;
  29
  30#if !ENABLE_FEATURE_NON_POSIX_CP
  31        if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) {
  32                /* Either it exists, or the *path* doesnt exist */
  33                bb_perror_msg("can't create '%s'", dest);
  34                return -1;
  35        }
  36#endif
  37        // else: act as if -f is always in effect.
  38        // We don't want "can't create" msg, we want unlink to be done
  39        // (silently unless -i). Why? POSIX cp usually succeeds with
  40        // O_TRUNC open of existing file, and user is left ignorantly happy.
  41        // With above block unconditionally enabled, non-POSIX cp
  42        // will complain a lot more than POSIX one.
  43
  44        /* TODO: maybe we should do it only if ctty is present? */
  45        if (flags & FILEUTILS_INTERACTIVE) {
  46                // We would not do POSIX insanity. -i asks,
  47                // then _unlinks_ the offender. Presto.
  48                // (No "opening without O_EXCL", no "unlink only if -f")
  49                // Or else we will end up having 3 open()s!
  50                fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest);
  51                if (!bb_ask_y_confirmation())
  52                        return 0; /* not allowed to overwrite */
  53        }
  54        if (unlink(dest) < 0) {
  55#if ENABLE_FEATURE_VERBOSE_CP_MESSAGE
  56                if (e == errno && e == ENOENT) {
  57                        /* e == ENOTDIR is similar: path has non-dir component,
  58                         * but in this case we don't even reach copy_file() */
  59                        bb_error_msg("can't create '%s': Path does not exist", dest);
  60                        return -1; /* error */
  61                }
  62#endif
  63                errno = e; /* do not use errno from unlink */
  64                bb_perror_msg("can't create '%s'", dest);
  65                return -1; /* error */
  66        }
  67#if ENABLE_FEATURE_CP_LONG_OPTIONS
  68        if (flags & FILEUTILS_RMDEST)
  69                if (flags & FILEUTILS_VERBOSE)
  70                        printf("removed '%s'\n", dest);
  71#endif
  72        return 1; /* ok (to try again) */
  73}
  74
  75/* Return:
  76 * -1 error, copy not made
  77 *  0 copy is made or user answered "no" in interactive mode
  78 *    (failures to preserve mode/owner/times are not reported in exit code)
  79 */
  80int FAST_FUNC copy_file(const char *source, const char *dest, int flags)
  81{
  82        /* This is a recursive function, try to minimize stack usage */
  83        /* NB: each struct stat is ~100 bytes */
  84        struct stat source_stat;
  85        struct stat dest_stat;
  86        smallint retval = 0;
  87        smallint dest_exists = 0;
  88        smallint ovr;
  89
  90/* Inverse of cp -d ("cp without -d") */
  91#define FLAGS_DEREF (flags & (FILEUTILS_DEREFERENCE + FILEUTILS_DEREFERENCE_L0))
  92
  93        if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) {
  94                /* This may be a dangling symlink.
  95                 * Making [sym]links to dangling symlinks works, so... */
  96                if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK))
  97                        goto make_links;
  98                bb_perror_msg("can't stat '%s'", source);
  99                return -1;
 100        }
 101
 102        if (lstat(dest, &dest_stat) < 0) {
 103                if (errno != ENOENT) {
 104                        bb_perror_msg("can't stat '%s'", dest);
 105                        return -1;
 106                }
 107        } else {
 108                if (source_stat.st_dev == dest_stat.st_dev
 109                 && source_stat.st_ino == dest_stat.st_ino
 110                ) {
 111                        bb_error_msg("'%s' and '%s' are the same file", source, dest);
 112                        return -1;
 113                }
 114                if (flags & FILEUTILS_NO_OVERWRITE) /* cp -n */
 115                        return 0;
 116                dest_exists = 1;
 117        }
 118
 119#if ENABLE_SELINUX
 120        if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) {
 121                security_context_t con;
 122                if (lgetfilecon(source, &con) >= 0) {
 123                        if (setfscreatecon(con) < 0) {
 124                                bb_perror_msg("can't set setfscreatecon %s", con);
 125                                freecon(con);
 126                                return -1;
 127                        }
 128                } else if (errno == ENOTSUP || errno == ENODATA) {
 129                        setfscreatecon_or_die(NULL);
 130                } else {
 131                        bb_perror_msg("can't lgetfilecon %s", source);
 132                        return -1;
 133                }
 134        }
 135#endif
 136
 137        if (S_ISDIR(source_stat.st_mode)) {
 138                DIR *dp;
 139                const char *tp;
 140                struct dirent *d;
 141                mode_t saved_umask = 0;
 142
 143                if (!(flags & FILEUTILS_RECUR)) {
 144                        bb_error_msg("omitting directory '%s'", source);
 145                        return -1;
 146                }
 147
 148                /* Did we ever create source ourself before? */
 149                tp = is_in_ino_dev_hashtable(&source_stat);
 150                if (tp) {
 151                        /* We did! it's a recursion! man the lifeboats... */
 152                        bb_error_msg("recursion detected, omitting directory '%s'",
 153                                        source);
 154                        return -1;
 155                }
 156
 157                if (dest_exists) {
 158                        if (!S_ISDIR(dest_stat.st_mode)) {
 159                                bb_error_msg("target '%s' is not a directory", dest);
 160                                return -1;
 161                        }
 162                        /* race here: user can substitute a symlink between
 163                         * this check and actual creation of files inside dest */
 164                } else {
 165                        /* Create DEST */
 166                        mode_t mode;
 167                        saved_umask = umask(0);
 168
 169                        mode = source_stat.st_mode;
 170                        if (!(flags & FILEUTILS_PRESERVE_STATUS))
 171                                mode = source_stat.st_mode & ~saved_umask;
 172                        /* Allow owner to access new dir (at least for now) */
 173                        mode |= S_IRWXU;
 174                        if (mkdir(dest, mode) < 0) {
 175                                umask(saved_umask);
 176                                bb_perror_msg("can't create directory '%s'", dest);
 177                                return -1;
 178                        }
 179                        umask(saved_umask);
 180                        /* need stat info for add_to_ino_dev_hashtable */
 181                        if (lstat(dest, &dest_stat) < 0) {
 182                                bb_perror_msg("can't stat '%s'", dest);
 183                                return -1;
 184                        }
 185                }
 186                /* remember (dev,inode) of each created dir.
 187                 * NULL: name is not remembered */
 188                add_to_ino_dev_hashtable(&dest_stat, NULL);
 189
 190                /* Recursively copy files in SOURCE */
 191                dp = opendir(source);
 192                if (dp == NULL) {
 193                        retval = -1;
 194                        goto preserve_mode_ugid_time;
 195                }
 196
 197                while ((d = readdir(dp)) != NULL) {
 198                        char *new_source, *new_dest;
 199
 200                        new_source = concat_subpath_file(source, d->d_name);
 201                        if (new_source == NULL)
 202                                continue;
 203                        new_dest = concat_path_file(dest, d->d_name);
 204                        if (copy_file(new_source, new_dest, flags & ~FILEUTILS_DEREFERENCE_L0) < 0)
 205                                retval = -1;
 206                        free(new_source);
 207                        free(new_dest);
 208                }
 209                closedir(dp);
 210
 211                if (!dest_exists
 212                 && chmod(dest, source_stat.st_mode & ~saved_umask) < 0
 213                ) {
 214                        bb_perror_msg("can't preserve %s of '%s'", "permissions", dest);
 215                        /* retval = -1; - WRONG! copy *WAS* made */
 216                }
 217                goto preserve_mode_ugid_time;
 218        }
 219
 220        if (dest_exists) {
 221                if (flags & FILEUTILS_UPDATE) {
 222                        if (source_stat.st_mtime <= dest_stat.st_mtime) {
 223                                return 0; /* source file must be newer */
 224                        }
 225                }
 226#if ENABLE_FEATURE_CP_LONG_OPTIONS
 227                if (flags & FILEUTILS_RMDEST) {
 228                        ovr = ask_and_unlink(dest, flags);
 229                        if (ovr <= 0)
 230                                return ovr;
 231                        dest_exists = 0;
 232                }
 233#endif
 234        }
 235
 236        if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
 237                int (*lf)(const char *oldpath, const char *newpath);
 238 make_links:
 239                /* Hmm... maybe
 240                 * if (DEREF && MAKE_SOFTLINK) source = realpath(source) ?
 241                 * (but realpath returns NULL on dangling symlinks...) */
 242                lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link;
 243                if (lf(source, dest) < 0) {
 244                        ovr = ask_and_unlink(dest, flags);
 245                        if (ovr <= 0)
 246                                return ovr;
 247                        if (lf(source, dest) < 0) {
 248                                bb_perror_msg("can't create link '%s'", dest);
 249                                return -1;
 250                        }
 251                }
 252                /* _Not_ jumping to preserve_mode_ugid_time:
 253                 * (sym)links don't have those */
 254                return 0;
 255        }
 256
 257        if (/* "cp thing1 thing2" without -R: just open and read() from thing1 */
 258            !(flags & FILEUTILS_RECUR)
 259            /* "cp [-opts] regular_file thing2" */
 260         || S_ISREG(source_stat.st_mode)
 261         /* DEREF uses stat, which never returns S_ISLNK() == true.
 262          * So the below is never true: */
 263         /* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */
 264        ) {
 265                int src_fd;
 266                int dst_fd;
 267                mode_t new_mode;
 268
 269                if (!FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) {
 270                        /* "cp -d symlink dst": create a link */
 271                        goto dont_cat;
 272                }
 273
 274                if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) {
 275                        const char *link_target;
 276                        link_target = is_in_ino_dev_hashtable(&source_stat);
 277                        if (link_target) {
 278                                if (link(link_target, dest) < 0) {
 279                                        ovr = ask_and_unlink(dest, flags);
 280                                        if (ovr <= 0)
 281                                                return ovr;
 282                                        if (link(link_target, dest) < 0) {
 283                                                bb_perror_msg("can't create link '%s'", dest);
 284                                                return -1;
 285                                        }
 286                                }
 287                                return 0;
 288                        }
 289                        add_to_ino_dev_hashtable(&source_stat, dest);
 290                }
 291
 292                src_fd = open_or_warn(source, O_RDONLY);
 293                if (src_fd < 0)
 294                        return -1;
 295
 296                /* Do not try to open with weird mode fields */
 297                new_mode = source_stat.st_mode;
 298                if (!S_ISREG(source_stat.st_mode))
 299                        new_mode = 0666;
 300
 301                if (ENABLE_FEATURE_NON_POSIX_CP || (flags & FILEUTILS_INTERACTIVE)) {
 302                        /*
 303                         * O_CREAT|O_EXCL: require that file did not exist before creation
 304                         */
 305                        dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
 306                } else { /* POSIX, and not "cp -i" */
 307                        /*
 308                         * O_CREAT|O_TRUNC: create, or truncate (security problem versus (sym)link attacks)
 309                         */
 310                        dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, new_mode);
 311                }
 312                if (dst_fd == -1) {
 313                        ovr = ask_and_unlink(dest, flags);
 314                        if (ovr <= 0) {
 315                                close(src_fd);
 316                                return ovr;
 317                        }
 318                        /* It shouldn't exist. If it exists, do not open (symlink attack?) */
 319                        dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
 320                        if (dst_fd < 0) {
 321                                close(src_fd);
 322                                return -1;
 323                        }
 324                }
 325
 326#if ENABLE_SELINUX
 327                if ((flags & (FILEUTILS_PRESERVE_SECURITY_CONTEXT|FILEUTILS_SET_SECURITY_CONTEXT))
 328                 && is_selinux_enabled() > 0
 329                ) {
 330                        security_context_t con;
 331                        if (getfscreatecon(&con) == -1) {
 332                                bb_simple_perror_msg("getfscreatecon");
 333                                return -1;
 334                        }
 335                        if (con) {
 336                                if (setfilecon(dest, con) == -1) {
 337                                        bb_perror_msg("setfilecon:%s,%s", dest, con);
 338                                        freecon(con);
 339                                        return -1;
 340                                }
 341                                freecon(con);
 342                        }
 343                }
 344#endif
 345#if ENABLE_FEATURE_CP_REFLINK
 346# undef BTRFS_IOCTL_MAGIC
 347# define BTRFS_IOCTL_MAGIC 0x94
 348# undef BTRFS_IOC_CLONE
 349# define BTRFS_IOC_CLONE _IOW (BTRFS_IOCTL_MAGIC, 9, int)
 350                if (flags & FILEUTILS_REFLINK) {
 351                        retval = ioctl(dst_fd, BTRFS_IOC_CLONE, src_fd);
 352                        if (retval == 0)
 353                                goto do_close;
 354                        /* reflink did not work */
 355                        if (flags & FILEUTILS_REFLINK_ALWAYS) {
 356                                bb_perror_msg("failed to clone '%s' from '%s'", dest, source);
 357                                goto do_close;
 358                        }
 359                        /* fall through to standard copy */
 360                        retval = 0;
 361                }
 362#endif
 363                if (bb_copyfd_eof(src_fd, dst_fd) == -1)
 364                        retval = -1;
 365 IF_FEATURE_CP_REFLINK(do_close:)
 366                /* Careful with writing... */
 367                if (close(dst_fd) < 0) {
 368                        bb_perror_msg("error writing to '%s'", dest);
 369                        retval = -1;
 370                }
 371                /* ...but read size is already checked by bb_copyfd_eof */
 372                close(src_fd);
 373                /* "cp /dev/something new_file" should not
 374                 * copy mode of /dev/something */
 375                if (!S_ISREG(source_stat.st_mode))
 376                        return retval;
 377                goto preserve_mode_ugid_time;
 378        }
 379 dont_cat:
 380
 381        /* Source is a symlink or a special file */
 382        /* We are lazy here, a bit lax with races... */
 383        if (dest_exists) {
 384                errno = EEXIST;
 385                ovr = ask_and_unlink(dest, flags);
 386                if (ovr <= 0)
 387                        return ovr;
 388        }
 389        if (S_ISLNK(source_stat.st_mode)) {
 390                char *lpath = xmalloc_readlink_or_warn(source);
 391                if (lpath) {
 392                        int r = symlink(lpath, dest);
 393                        if (r < 0) {
 394                                /* shared message */
 395                                bb_perror_msg("can't create %slink '%s' to '%s'",
 396                                        "sym", dest, lpath
 397                                );
 398                                free(lpath);
 399                                return -1;
 400                        }
 401                        free(lpath);
 402                        if (flags & FILEUTILS_PRESERVE_STATUS)
 403                                if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
 404                                        bb_perror_msg("can't preserve %s of '%s'", "ownership", dest);
 405                }
 406                /* _Not_ jumping to preserve_mode_ugid_time:
 407                 * symlinks don't have those */
 408                goto verb_and_exit;
 409        }
 410        if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode)
 411         || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode)
 412        ) {
 413                if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
 414                        bb_perror_msg("can't create '%s'", dest);
 415                        return -1;
 416                }
 417        } else {
 418                bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode);
 419                return -1;
 420        }
 421
 422 preserve_mode_ugid_time:
 423
 424        if (flags & FILEUTILS_PRESERVE_STATUS
 425        /* Cannot happen: */
 426        /* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */
 427        ) {
 428                struct timeval times[2];
 429
 430                times[1].tv_sec = times[0].tv_sec = source_stat.st_mtime;
 431                times[1].tv_usec = times[0].tv_usec = 0;
 432                /* BTW, utimes sets usec-precision time - just FYI */
 433                if (utimes(dest, times) < 0)
 434                        bb_perror_msg("can't preserve %s of '%s'", "times", dest);
 435                if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) {
 436                        source_stat.st_mode &= ~(S_ISUID | S_ISGID);
 437                        bb_perror_msg("can't preserve %s of '%s'", "ownership", dest);
 438                }
 439                if (chmod(dest, source_stat.st_mode) < 0)
 440                        bb_perror_msg("can't preserve %s of '%s'", "permissions", dest);
 441        }
 442
 443 verb_and_exit:
 444        if (flags & FILEUTILS_VERBOSE) {
 445                printf("'%s' -> '%s'\n", source, dest);
 446        }
 447
 448        return retval;
 449}
 450