busybox/libbb/copy_file.c
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   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                dest_exists = 1;
 115        }
 116
 117#if ENABLE_SELINUX
 118        if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) {
 119                security_context_t con;
 120                if (lgetfilecon(source, &con) >= 0) {
 121                        if (setfscreatecon(con) < 0) {
 122                                bb_perror_msg("can't set setfscreatecon %s", con);
 123                                freecon(con);
 124                                return -1;
 125                        }
 126                } else if (errno == ENOTSUP || errno == ENODATA) {
 127                        setfscreatecon_or_die(NULL);
 128                } else {
 129                        bb_perror_msg("can't lgetfilecon %s", source);
 130                        return -1;
 131                }
 132        }
 133#endif
 134
 135        if (S_ISDIR(source_stat.st_mode)) {
 136                DIR *dp;
 137                const char *tp;
 138                struct dirent *d;
 139                mode_t saved_umask = 0;
 140
 141                if (!(flags & FILEUTILS_RECUR)) {
 142                        bb_error_msg("omitting directory '%s'", source);
 143                        return -1;
 144                }
 145
 146                /* Did we ever create source ourself before? */
 147                tp = is_in_ino_dev_hashtable(&source_stat);
 148                if (tp) {
 149                        /* We did! it's a recursion! man the lifeboats... */
 150                        bb_error_msg("recursion detected, omitting directory '%s'",
 151                                        source);
 152                        return -1;
 153                }
 154
 155                if (dest_exists) {
 156                        if (!S_ISDIR(dest_stat.st_mode)) {
 157                                bb_error_msg("target '%s' is not a directory", dest);
 158                                return -1;
 159                        }
 160                        /* race here: user can substitute a symlink between
 161                         * this check and actual creation of files inside dest */
 162                } else {
 163                        /* Create DEST */
 164                        mode_t mode;
 165                        saved_umask = umask(0);
 166
 167                        mode = source_stat.st_mode;
 168                        if (!(flags & FILEUTILS_PRESERVE_STATUS))
 169                                mode = source_stat.st_mode & ~saved_umask;
 170                        /* Allow owner to access new dir (at least for now) */
 171                        mode |= S_IRWXU;
 172                        if (mkdir(dest, mode) < 0) {
 173                                umask(saved_umask);
 174                                bb_perror_msg("can't create directory '%s'", dest);
 175                                return -1;
 176                        }
 177                        umask(saved_umask);
 178                        /* need stat info for add_to_ino_dev_hashtable */
 179                        if (lstat(dest, &dest_stat) < 0) {
 180                                bb_perror_msg("can't stat '%s'", dest);
 181                                return -1;
 182                        }
 183                }
 184                /* remember (dev,inode) of each created dir.
 185                 * NULL: name is not remembered */
 186                add_to_ino_dev_hashtable(&dest_stat, NULL);
 187
 188                /* Recursively copy files in SOURCE */
 189                dp = opendir(source);
 190                if (dp == NULL) {
 191                        retval = -1;
 192                        goto preserve_mode_ugid_time;
 193                }
 194
 195                while ((d = readdir(dp)) != NULL) {
 196                        char *new_source, *new_dest;
 197
 198                        new_source = concat_subpath_file(source, d->d_name);
 199                        if (new_source == NULL)
 200                                continue;
 201                        new_dest = concat_path_file(dest, d->d_name);
 202                        if (copy_file(new_source, new_dest, flags & ~FILEUTILS_DEREFERENCE_L0) < 0)
 203                                retval = -1;
 204                        free(new_source);
 205                        free(new_dest);
 206                }
 207                closedir(dp);
 208
 209                if (!dest_exists
 210                 && chmod(dest, source_stat.st_mode & ~saved_umask) < 0
 211                ) {
 212                        bb_perror_msg("can't preserve %s of '%s'", "permissions", dest);
 213                        /* retval = -1; - WRONG! copy *WAS* made */
 214                }
 215                goto preserve_mode_ugid_time;
 216        }
 217
 218        if (dest_exists) {
 219                if (flags & FILEUTILS_UPDATE) {
 220                        if (source_stat.st_mtime <= dest_stat.st_mtime) {
 221                                return 0; /* source file must be newer */
 222                        }
 223                }
 224#if ENABLE_FEATURE_CP_LONG_OPTIONS
 225                if (flags & FILEUTILS_RMDEST) {
 226                        ovr = ask_and_unlink(dest, flags);
 227                        if (ovr <= 0)
 228                                return ovr;
 229                        dest_exists = 0;
 230                }
 231#endif
 232        }
 233
 234        if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
 235                int (*lf)(const char *oldpath, const char *newpath);
 236 make_links:
 237                /* Hmm... maybe
 238                 * if (DEREF && MAKE_SOFTLINK) source = realpath(source) ?
 239                 * (but realpath returns NULL on dangling symlinks...) */
 240                lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link;
 241                if (lf(source, dest) < 0) {
 242                        ovr = ask_and_unlink(dest, flags);
 243                        if (ovr <= 0)
 244                                return ovr;
 245                        if (lf(source, dest) < 0) {
 246                                bb_perror_msg("can't create link '%s'", dest);
 247                                return -1;
 248                        }
 249                }
 250                /* _Not_ jumping to preserve_mode_ugid_time:
 251                 * (sym)links don't have those */
 252                return 0;
 253        }
 254
 255        if (/* "cp thing1 thing2" without -R: just open and read() from thing1 */
 256            !(flags & FILEUTILS_RECUR)
 257            /* "cp [-opts] regular_file thing2" */
 258         || S_ISREG(source_stat.st_mode)
 259         /* DEREF uses stat, which never returns S_ISLNK() == true.
 260          * So the below is never true: */
 261         /* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */
 262        ) {
 263                int src_fd;
 264                int dst_fd;
 265                mode_t new_mode;
 266
 267                if (!FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) {
 268                        /* "cp -d symlink dst": create a link */
 269                        goto dont_cat;
 270                }
 271
 272                if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) {
 273                        const char *link_target;
 274                        link_target = is_in_ino_dev_hashtable(&source_stat);
 275                        if (link_target) {
 276                                if (link(link_target, dest) < 0) {
 277                                        ovr = ask_and_unlink(dest, flags);
 278                                        if (ovr <= 0)
 279                                                return ovr;
 280                                        if (link(link_target, dest) < 0) {
 281                                                bb_perror_msg("can't create link '%s'", dest);
 282                                                return -1;
 283                                        }
 284                                }
 285                                return 0;
 286                        }
 287                        add_to_ino_dev_hashtable(&source_stat, dest);
 288                }
 289
 290                src_fd = open_or_warn(source, O_RDONLY);
 291                if (src_fd < 0)
 292                        return -1;
 293
 294                /* Do not try to open with weird mode fields */
 295                new_mode = source_stat.st_mode;
 296                if (!S_ISREG(source_stat.st_mode))
 297                        new_mode = 0666;
 298
 299                if (ENABLE_FEATURE_NON_POSIX_CP || (flags & FILEUTILS_INTERACTIVE)) {
 300                        /*
 301                         * O_CREAT|O_EXCL: require that file did not exist before creation
 302                         */
 303                        dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
 304                } else { /* POSIX, and not "cp -i" */
 305                        /*
 306                         * O_CREAT|O_TRUNC: create, or truncate (security problem versus (sym)link attacks)
 307                         */
 308                        dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, new_mode);
 309                }
 310                if (dst_fd == -1) {
 311                        ovr = ask_and_unlink(dest, flags);
 312                        if (ovr <= 0) {
 313                                close(src_fd);
 314                                return ovr;
 315                        }
 316                        /* It shouldn't exist. If it exists, do not open (symlink attack?) */
 317                        dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
 318                        if (dst_fd < 0) {
 319                                close(src_fd);
 320                                return -1;
 321                        }
 322                }
 323
 324#if ENABLE_SELINUX
 325                if ((flags & (FILEUTILS_PRESERVE_SECURITY_CONTEXT|FILEUTILS_SET_SECURITY_CONTEXT))
 326                 && is_selinux_enabled() > 0
 327                ) {
 328                        security_context_t con;
 329                        if (getfscreatecon(&con) == -1) {
 330                                bb_perror_msg("getfscreatecon");
 331                                return -1;
 332                        }
 333                        if (con) {
 334                                if (setfilecon(dest, con) == -1) {
 335                                        bb_perror_msg("setfilecon:%s,%s", dest, con);
 336                                        freecon(con);
 337                                        return -1;
 338                                }
 339                                freecon(con);
 340                        }
 341                }
 342#endif
 343#if ENABLE_FEATURE_CP_REFLINK
 344# undef BTRFS_IOCTL_MAGIC
 345# define BTRFS_IOCTL_MAGIC 0x94
 346# undef BTRFS_IOC_CLONE
 347# define BTRFS_IOC_CLONE _IOW (BTRFS_IOCTL_MAGIC, 9, int)
 348                if (flags & FILEUTILS_REFLINK) {
 349                        retval = ioctl(dst_fd, BTRFS_IOC_CLONE, src_fd);
 350                        if (retval == 0)
 351                                goto do_close;
 352                        /* reflink did not work */
 353                        if (flags & FILEUTILS_REFLINK_ALWAYS) {
 354                                bb_perror_msg("failed to clone '%s' from '%s'", dest, source);
 355                                goto do_close;
 356                        }
 357                        /* fall through to standard copy */
 358                        retval = 0;
 359                }
 360#endif
 361                if (bb_copyfd_eof(src_fd, dst_fd) == -1)
 362                        retval = -1;
 363 IF_FEATURE_CP_REFLINK(do_close:)
 364                /* Careful with writing... */
 365                if (close(dst_fd) < 0) {
 366                        bb_perror_msg("error writing to '%s'", dest);
 367                        retval = -1;
 368                }
 369                /* ...but read size is already checked by bb_copyfd_eof */
 370                close(src_fd);
 371                /* "cp /dev/something new_file" should not
 372                 * copy mode of /dev/something */
 373                if (!S_ISREG(source_stat.st_mode))
 374                        return retval;
 375                goto preserve_mode_ugid_time;
 376        }
 377 dont_cat:
 378
 379        /* Source is a symlink or a special file */
 380        /* We are lazy here, a bit lax with races... */
 381        if (dest_exists) {
 382                errno = EEXIST;
 383                ovr = ask_and_unlink(dest, flags);
 384                if (ovr <= 0)
 385                        return ovr;
 386        }
 387        if (S_ISLNK(source_stat.st_mode)) {
 388                char *lpath = xmalloc_readlink_or_warn(source);
 389                if (lpath) {
 390                        int r = symlink(lpath, dest);
 391                        if (r < 0) {
 392                                /* shared message */
 393                                bb_perror_msg("can't create %slink '%s' to '%s'",
 394                                        "sym", dest, lpath
 395                                );
 396                                free(lpath);
 397                                return -1;
 398                        }
 399                        free(lpath);
 400                        if (flags & FILEUTILS_PRESERVE_STATUS)
 401                                if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
 402                                        bb_perror_msg("can't preserve %s of '%s'", "ownership", dest);
 403                }
 404                /* _Not_ jumping to preserve_mode_ugid_time:
 405                 * symlinks don't have those */
 406                goto verb_and_exit;
 407        }
 408        if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode)
 409         || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode)
 410        ) {
 411                if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
 412                        bb_perror_msg("can't create '%s'", dest);
 413                        return -1;
 414                }
 415        } else {
 416                bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode);
 417                return -1;
 418        }
 419
 420 preserve_mode_ugid_time:
 421
 422        if (flags & FILEUTILS_PRESERVE_STATUS
 423        /* Cannot happen: */
 424        /* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */
 425        ) {
 426                struct timeval times[2];
 427
 428                times[1].tv_sec = times[0].tv_sec = source_stat.st_mtime;
 429                times[1].tv_usec = times[0].tv_usec = 0;
 430                /* BTW, utimes sets usec-precision time - just FYI */
 431                if (utimes(dest, times) < 0)
 432                        bb_perror_msg("can't preserve %s of '%s'", "times", dest);
 433                if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) {
 434                        source_stat.st_mode &= ~(S_ISUID | S_ISGID);
 435                        bb_perror_msg("can't preserve %s of '%s'", "ownership", dest);
 436                }
 437                if (chmod(dest, source_stat.st_mode) < 0)
 438                        bb_perror_msg("can't preserve %s of '%s'", "permissions", dest);
 439        }
 440
 441 verb_and_exit:
 442        if (flags & FILEUTILS_VERBOSE) {
 443                printf("'%s' -> '%s'\n", source, dest);
 444        }
 445
 446        return retval;
 447}
 448
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