src/basic/copy.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2014 Lennart Poettering
   6 ***/
   7
   8 #include <dirent.h>
   9 #include <errno.h>
  10 #include <fcntl.h>
  11 #include <stddef.h>
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include <string.h>
  15 #include <sys/sendfile.h>
  16 #include <sys/stat.h>
  17 #include <sys/xattr.h>
  18 #include <time.h>
  19 #include <unistd.h>
  20
  21 #include "alloc-util.h"
  22 #include "btrfs-util.h"
  23 #include "chattr-util.h"
  24 #include "copy.h"
  25 #include "dirent-util.h"
  26 #include "fd-util.h"
  27 #include "fileio.h"
  28 #include "fs-util.h"
  29 #include "io-util.h"
  30 #include "macro.h"
  31 #include "missing.h"
  32 #include "string-util.h"
  33 #include "strv.h"
  34 #include "time-util.h"
  35 #include "umask-util.h"
  36 #include "user-util.h"
  37 #include "xattr-util.h"
  38
  39 #define COPY_BUFFER_SIZE (16*1024u)
  40
  41 static ssize_t try_copy_file_range(
  42                 int fd_in, loff_t *off_in,
  43                 int fd_out, loff_t *off_out,
  44                 size_t len,
  45                 unsigned int flags) {
  46
  47         static int have = -1;
  48         ssize_t r;
  49
  50         if (have == 0)
  51                 return -ENOSYS;
  52
  53         r = copy_file_range(fd_in, off_in, fd_out, off_out, len, flags);
  54         if (have < 0)
  55                 have = r >= 0 || errno != ENOSYS;
  56         if (r < 0)
  57                 return -errno;
  58
  59         return r;
  60 }
  61
  62 enum {
  63         FD_IS_NO_PIPE,
  64         FD_IS_BLOCKING_PIPE,
  65         FD_IS_NONBLOCKING_PIPE,
  66 };
  67
  68 static int fd_is_nonblock_pipe(int fd) {
  69         struct stat st;
  70         int flags;
  71
  72         /* Checks whether the specified file descriptor refers to a pipe, and if so if O_NONBLOCK is set. */
  73
  74         if (fstat(fd, &st) < 0)
  75                 return -errno;
  76
  77         if (!S_ISFIFO(st.st_mode))
  78                 return FD_IS_NO_PIPE;
  79
  80         flags = fcntl(fd, F_GETFL);
  81         if (flags < 0)
  82                 return -errno;
  83
  84         return FLAGS_SET(flags, O_NONBLOCK) ? FD_IS_NONBLOCKING_PIPE : FD_IS_BLOCKING_PIPE;
  85 }
  86
  87 int copy_bytes_full(
  88                 int fdf, int fdt,
  89                 uint64_t max_bytes,
  90                 CopyFlags copy_flags,
  91                 void **ret_remains,
  92                 size_t *ret_remains_size) {
  93
  94         bool try_cfr = true, try_sendfile = true, try_splice = true;
  95         int r, nonblock_pipe = -1;
  96         size_t m = SSIZE_MAX; /* that is the maximum that sendfile and c_f_r accept */
  97
  98         assert(fdf >= 0);
  99         assert(fdt >= 0);
 100
 101         /* Tries to copy bytes from the file descriptor 'fdf' to 'fdt' in the smartest possible way. Copies a maximum
 102          * of 'max_bytes', which may be specified as UINT64_MAX, in which no maximum is applied. Returns negative on
 103          * error, zero if EOF is hit before the bytes limit is hit and positive otherwise. If the copy fails for some
 104          * reason but we read but didn't yet write some data an ret_remains/ret_remains_size is not NULL, then it will
 105          * be initialized with an allocated buffer containing this "remaining" data. Note that these two parameters are
 106          * initialized with a valid buffer only on failure and only if there's actually data already read. Otherwise
 107          * these parameters if non-NULL are set to NULL. */
 108
 109         if (ret_remains)
 110                 *ret_remains = NULL;
 111         if (ret_remains_size)
 112                 *ret_remains_size = 0;
 113
 114         /* Try btrfs reflinks first. This only works on regular, seekable files, hence let's check the file offsets of
 115          * source and destination first. */
 116         if ((copy_flags & COPY_REFLINK)) {
 117                 off_t foffset;
 118
 119                 foffset = lseek(fdf, 0, SEEK_CUR);
 120                 if (foffset >= 0) {
 121                         off_t toffset;
 122
 123                         toffset = lseek(fdt, 0, SEEK_CUR);
 124                         if (toffset >= 0) {
 125
 126                                 if (foffset == 0 && toffset == 0 && max_bytes == UINT64_MAX)
 127                                         r = btrfs_reflink(fdf, fdt); /* full file reflink */
 128                                 else
 129                                         r = btrfs_clone_range(fdf, foffset, fdt, toffset, max_bytes == UINT64_MAX ? 0 : max_bytes); /* partial reflink */
 130                                 if (r >= 0) {
 131                                         off_t t;
 132
 133                                         /* This worked, yay! Now — to be fully correct — let's adjust the file pointers */
 134                                         if (max_bytes == UINT64_MAX) {
 135
 136                                                 /* We cloned to the end of the source file, let's position the read
 137                                                  * pointer there, and query it at the same time. */
 138                                                 t = lseek(fdf, 0, SEEK_END);
 139                                                 if (t < 0)
 140                                                         return -errno;
 141                                                 if (t < foffset)
 142                                                         return -ESPIPE;
 143
 144                                                 /* Let's adjust the destination file write pointer by the same number
 145                                                  * of bytes. */
 146                                                 t = lseek(fdt, toffset + (t - foffset), SEEK_SET);
 147                                                 if (t < 0)
 148                                                         return -errno;
 149
 150                                                 return 0; /* we copied the whole thing, hence hit EOF, return 0 */
 151                                         } else {
 152                                                 t = lseek(fdf, foffset + max_bytes, SEEK_SET);
 153                                                 if (t < 0)
 154                                                         return -errno;
 155
 156                                                 t = lseek(fdt, toffset + max_bytes, SEEK_SET);
 157                                                 if (t < 0)
 158                                                         return -errno;
 159
 160                                                 return 1; /* we copied only some number of bytes, which worked, but this means we didn't hit EOF, return 1 */
 161                                         }
 162                                 }
 163
 164                                 log_debug_errno(r, "Reflinking didn't work, falling back to non-reflink copying: %m");
 165                         }
 166                 }
 167         }
 168
 169         for (;;) {
 170                 ssize_t n;
 171
 172                 if (max_bytes <= 0)
 173                         return 1; /* return > 0 if we hit the max_bytes limit */
 174
 175                 if (max_bytes != UINT64_MAX && m > max_bytes)
 176                         m = max_bytes;
 177
 178                 /* First try copy_file_range(), unless we already tried */
 179                 if (try_cfr) {
 180                         n = try_copy_file_range(fdf, NULL, fdt, NULL, m, 0u);
 181                         if (n < 0) {
 182                                 if (!IN_SET(n, -EINVAL, -ENOSYS, -EXDEV, -EBADF))
 183                                         return n;
 184
 185                                 try_cfr = false;
 186                                 /* use fallback below */
 187                         } else if (n == 0) /* EOF */
 188                                 break;
 189                         else
 190                                 /* Success! */
 191                                 goto next;
 192                 }
 193
 194                 /* First try sendfile(), unless we already tried */
 195                 if (try_sendfile) {
 196                         n = sendfile(fdt, fdf, NULL, m);
 197                         if (n < 0) {
 198                                 if (!IN_SET(errno, EINVAL, ENOSYS))
 199                                         return -errno;
 200
 201                                 try_sendfile = false;
 202                                 /* use fallback below */
 203                         } else if (n == 0) /* EOF */
 204                                 break;
 205                         else
 206                                 /* Success! */
 207                                 goto next;
 208                 }
 209
 210                 /* Then try splice, unless we already tried. */
 211                 if (try_splice) {
 212
 213                         /* splice()'s asynchronous I/O support is a bit weird. When it encounters a pipe file
 214                          * descriptor, then it will ignore its O_NONBLOCK flag and instead only honour the
 215                          * SPLICE_F_NONBLOCK flag specified in its flag parameter. Let's hide this behaviour here, and
 216                          * check if either of the specified fds are a pipe, and if so, let's pass the flag
 217                          * automatically, depending on O_NONBLOCK being set.
 218                          *
 219                          * Here's a twist though: when we use it to move data between two pipes of which one has
 220                          * O_NONBLOCK set and the other has not, then we have no individual control over O_NONBLOCK
 221                          * behaviour. Hence in that case we can't use splice() and still guarantee systematic
 222                          * O_NONBLOCK behaviour, hence don't. */
 223
 224                         if (nonblock_pipe < 0) {
 225                                 int a, b;
 226
 227                                 /* Check if either of these fds is a pipe, and if so non-blocking or not */
 228                                 a = fd_is_nonblock_pipe(fdf);
 229                                 if (a < 0)
 230                                         return a;
 231
 232                                 b = fd_is_nonblock_pipe(fdt);
 233                                 if (b < 0)
 234                                         return b;
 235
 236                                 if ((a == FD_IS_NO_PIPE && b == FD_IS_NO_PIPE) ||
 237                                     (a == FD_IS_BLOCKING_PIPE && b == FD_IS_NONBLOCKING_PIPE) ||
 238                                     (a == FD_IS_NONBLOCKING_PIPE && b == FD_IS_BLOCKING_PIPE))
 239
 240                                         /* splice() only works if one of the fds is a pipe. If neither is, let's skip
 241                                          * this step right-away. As mentioned above, if one of the two fds refers to a
 242                                          * blocking pipe and the other to a non-blocking pipe, we can't use splice()
 243                                          * either, hence don't try either. This hence means we can only use splice() if
 244                                          * either only one of the two fds is a pipe, or if both are pipes with the same
 245                                          * nonblocking flag setting. */
 246
 247                                         try_splice = false;
 248                                 else
 249                                         nonblock_pipe = a == FD_IS_NONBLOCKING_PIPE || b == FD_IS_NONBLOCKING_PIPE;
 250                         }
 251                 }
 252
 253                 if (try_splice) {
 254                         n = splice(fdf, NULL, fdt, NULL, m, nonblock_pipe ? SPLICE_F_NONBLOCK : 0);
 255                         if (n < 0) {
 256                                 if (!IN_SET(errno, EINVAL, ENOSYS))
 257                                         return -errno;
 258
 259                                 try_splice = false;
 260                                 /* use fallback below */
 261                         } else if (n == 0) /* EOF */
 262                                 break;
 263                         else
 264                                 /* Success! */
 265                                 goto next;
 266                 }
 267
 268                 /* As a fallback just copy bits by hand */
 269                 {
 270                         uint8_t buf[MIN(m, COPY_BUFFER_SIZE)], *p = buf;
 271                         ssize_t z;
 272
 273                         n = read(fdf, buf, sizeof buf);
 274                         if (n < 0)
 275                                 return -errno;
 276                         if (n == 0) /* EOF */
 277                                 break;
 278
 279                         z = (size_t) n;
 280                         do {
 281                                 ssize_t k;
 282
 283                                 k = write(fdt, p, z);
 284                                 if (k < 0) {
 285                                         r = -errno;
 286
 287                                         if (ret_remains) {
 288                                                 void *copy;
 289
 290                                                 copy = memdup(p, z);
 291                                                 if (!copy)
 292                                                         return -ENOMEM;
 293
 294                                                 *ret_remains = copy;
 295                                         }
 296
 297                                         if (ret_remains_size)
 298                                                 *ret_remains_size = z;
 299
 300                                         return r;
 301                                 }
 302
 303                                 assert(k <= z);
 304                                 z -= k;
 305                                 p += k;
 306                         } while (z > 0);
 307                 }
 308
 309         next:
 310                 if (max_bytes != (uint64_t) -1) {
 311                         assert(max_bytes >= (uint64_t) n);
 312                         max_bytes -= n;
 313                 }
 314                 /* sendfile accepts at most SSIZE_MAX-offset bytes to copy,
 315                  * so reduce our maximum by the amount we already copied,
 316                  * but don't go below our copy buffer size, unless we are
 317                  * close the limit of bytes we are allowed to copy. */
 318                 m = MAX(MIN(COPY_BUFFER_SIZE, max_bytes), m - n);
 319         }
 320
 321         return 0; /* return 0 if we hit EOF earlier than the size limit */
 322 }
 323
 324 static int fd_copy_symlink(
 325                 int df,
 326                 const char *from,
 327                 const struct stat *st,
 328                 int dt,
 329                 const char *to,
 330                 uid_t override_uid,
 331                 gid_t override_gid,
 332                 CopyFlags copy_flags) {
 333
 334         _cleanup_free_ char *target = NULL;
 335         int r;
 336
 337         assert(from);
 338         assert(st);
 339         assert(to);
 340
 341         r = readlinkat_malloc(df, from, &target);
 342         if (r < 0)
 343                 return r;
 344
 345         if (symlinkat(target, dt, to) < 0)
 346                 return -errno;
 347
 348         if (fchownat(dt, to,
 349                      uid_is_valid(override_uid) ? override_uid : st->st_uid,
 350                      gid_is_valid(override_gid) ? override_gid : st->st_gid,
 351                      AT_SYMLINK_NOFOLLOW) < 0)
 352                 return -errno;
 353
 354         return 0;
 355 }
 356
 357 static int fd_copy_regular(
 358                 int df,
 359                 const char *from,
 360                 const struct stat *st,
 361                 int dt,
 362                 const char *to,
 363                 uid_t override_uid,
 364                 gid_t override_gid,
 365                 CopyFlags copy_flags) {
 366
 367         _cleanup_close_ int fdf = -1, fdt = -1;
 368         struct timespec ts[2];
 369         int r, q;
 370
 371         assert(from);
 372         assert(st);
 373         assert(to);
 374
 375         fdf = openat(df, from, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
 376         if (fdf < 0)
 377                 return -errno;
 378
 379         fdt = openat(dt, to, O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, st->st_mode & 07777);
 380         if (fdt < 0)
 381                 return -errno;
 382
 383         r = copy_bytes(fdf, fdt, (uint64_t) -1, copy_flags);
 384         if (r < 0) {
 385                 (void) unlinkat(dt, to, 0);
 386                 return r;
 387         }
 388
 389         if (fchown(fdt,
 390                    uid_is_valid(override_uid) ? override_uid : st->st_uid,
 391                    gid_is_valid(override_gid) ? override_gid : st->st_gid) < 0)
 392                 r = -errno;
 393
 394         if (fchmod(fdt, st->st_mode & 07777) < 0)
 395                 r = -errno;
 396
 397         ts[0] = st->st_atim;
 398         ts[1] = st->st_mtim;
 399         (void) futimens(fdt, ts);
 400         (void) copy_xattr(fdf, fdt);
 401
 402         q = close(fdt);
 403         fdt = -1;
 404
 405         if (q < 0) {
 406                 r = -errno;
 407                 (void) unlinkat(dt, to, 0);
 408         }
 409
 410         return r;
 411 }
 412
 413 static int fd_copy_fifo(
 414                 int df,
 415                 const char *from,
 416                 const struct stat *st,
 417                 int dt,
 418                 const char *to,
 419                 uid_t override_uid,
 420                 gid_t override_gid,
 421                 CopyFlags copy_flags) {
 422         int r;
 423
 424         assert(from);
 425         assert(st);
 426         assert(to);
 427
 428         r = mkfifoat(dt, to, st->st_mode & 07777);
 429         if (r < 0)
 430                 return -errno;
 431
 432         if (fchownat(dt, to,
 433                      uid_is_valid(override_uid) ? override_uid : st->st_uid,
 434                      gid_is_valid(override_gid) ? override_gid : st->st_gid,
 435                      AT_SYMLINK_NOFOLLOW) < 0)
 436                 r = -errno;
 437
 438         if (fchmodat(dt, to, st->st_mode & 07777, 0) < 0)
 439                 r = -errno;
 440
 441         return r;
 442 }
 443
 444 static int fd_copy_node(
 445                 int df,
 446                 const char *from,
 447                 const struct stat *st,
 448                 int dt,
 449                 const char *to,
 450                 uid_t override_uid,
 451                 gid_t override_gid,
 452                 CopyFlags copy_flags) {
 453         int r;
 454
 455         assert(from);
 456         assert(st);
 457         assert(to);
 458
 459         r = mknodat(dt, to, st->st_mode, st->st_rdev);
 460         if (r < 0)
 461                 return -errno;
 462
 463         if (fchownat(dt, to,
 464                      uid_is_valid(override_uid) ? override_uid : st->st_uid,
 465                      gid_is_valid(override_gid) ? override_gid : st->st_gid,
 466                      AT_SYMLINK_NOFOLLOW) < 0)
 467                 r = -errno;
 468
 469         if (fchmodat(dt, to, st->st_mode & 07777, 0) < 0)
 470                 r = -errno;
 471
 472         return r;
 473 }
 474
 475 static int fd_copy_directory(
 476                 int df,
 477                 const char *from,
 478                 const struct stat *st,
 479                 int dt,
 480                 const char *to,
 481                 dev_t original_device,
 482                 uid_t override_uid,
 483                 gid_t override_gid,
 484                 CopyFlags copy_flags) {
 485
 486         _cleanup_close_ int fdf = -1, fdt = -1;
 487         _cleanup_closedir_ DIR *d = NULL;
 488         struct dirent *de;
 489         bool created;
 490         int r;
 491
 492         assert(st);
 493         assert(to);
 494
 495         if (from)
 496                 fdf = openat(df, from, O_RDONLY|O_DIRECTORY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
 497         else
 498                 fdf = fcntl(df, F_DUPFD_CLOEXEC, 3);
 499         if (fdf < 0)
 500                 return -errno;
 501
 502         d = fdopendir(fdf);
 503         if (!d)
 504                 return -errno;
 505         fdf = -1;
 506
 507         r = mkdirat(dt, to, st->st_mode & 07777);
 508         if (r >= 0)
 509                 created = true;
 510         else if (errno == EEXIST && (copy_flags & COPY_MERGE))
 511                 created = false;
 512         else
 513                 return -errno;
 514
 515         fdt = openat(dt, to, O_RDONLY|O_DIRECTORY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
 516         if (fdt < 0)
 517                 return -errno;
 518
 519         r = 0;
 520
 521         FOREACH_DIRENT_ALL(de, d, return -errno) {
 522                 struct stat buf;
 523                 int q;
 524
 525                 if (dot_or_dot_dot(de->d_name))
 526                         continue;
 527
 528                 if (fstatat(dirfd(d), de->d_name, &buf, AT_SYMLINK_NOFOLLOW) < 0) {
 529                         r = -errno;
 530                         continue;
 531                 }
 532
 533                 if (buf.st_dev != original_device)
 534                         continue;
 535
 536                 if (S_ISREG(buf.st_mode))
 537                         q = fd_copy_regular(dirfd(d), de->d_name, &buf, fdt, de->d_name, override_uid, override_gid, copy_flags);
 538                 else if (S_ISDIR(buf.st_mode))
 539                         q = fd_copy_directory(dirfd(d), de->d_name, &buf, fdt, de->d_name, original_device, override_uid, override_gid, copy_flags);
 540                 else if (S_ISLNK(buf.st_mode))
 541                         q = fd_copy_symlink(dirfd(d), de->d_name, &buf, fdt, de->d_name, override_uid, override_gid, copy_flags);
 542                 else if (S_ISFIFO(buf.st_mode))
 543                         q = fd_copy_fifo(dirfd(d), de->d_name, &buf, fdt, de->d_name, override_uid, override_gid, copy_flags);
 544                 else if (S_ISBLK(buf.st_mode) || S_ISCHR(buf.st_mode) || S_ISSOCK(buf.st_mode))
 545                         q = fd_copy_node(dirfd(d), de->d_name, &buf, fdt, de->d_name, override_uid, override_gid, copy_flags);
 546                 else
 547                         q = -EOPNOTSUPP;
 548
 549                 if (q == -EEXIST && (copy_flags & COPY_MERGE))
 550                         q = 0;
 551
 552                 if (q < 0)
 553                         r = q;
 554         }
 555
 556         if (created) {
 557                 struct timespec ut[2] = {
 558                         st->st_atim,
 559                         st->st_mtim
 560                 };
 561
 562                 if (fchown(fdt,
 563                            uid_is_valid(override_uid) ? override_uid : st->st_uid,
 564                            gid_is_valid(override_gid) ? override_gid : st->st_gid) < 0)
 565                         r = -errno;
 566
 567                 if (fchmod(fdt, st->st_mode & 07777) < 0)
 568                         r = -errno;
 569
 570                 (void) copy_xattr(dirfd(d), fdt);
 571                 (void) futimens(fdt, ut);
 572         }
 573
 574         return r;
 575 }
 576
 577 int copy_tree_at(int fdf, const char *from, int fdt, const char *to, uid_t override_uid, gid_t override_gid, CopyFlags copy_flags) {
 578         struct stat st;
 579
 580         assert(from);
 581         assert(to);
 582
 583         if (fstatat(fdf, from, &st, AT_SYMLINK_NOFOLLOW) < 0)
 584                 return -errno;
 585
 586         if (S_ISREG(st.st_mode))
 587                 return fd_copy_regular(fdf, from, &st, fdt, to, override_uid, override_gid, copy_flags);
 588         else if (S_ISDIR(st.st_mode))
 589                 return fd_copy_directory(fdf, from, &st, fdt, to, st.st_dev, override_uid, override_gid, copy_flags);
 590         else if (S_ISLNK(st.st_mode))
 591                 return fd_copy_symlink(fdf, from, &st, fdt, to, override_uid, override_gid, copy_flags);
 592         else if (S_ISFIFO(st.st_mode))
 593                 return fd_copy_fifo(fdf, from, &st, fdt, to, override_uid, override_gid, copy_flags);
 594         else if (S_ISBLK(st.st_mode) || S_ISCHR(st.st_mode) || S_ISSOCK(st.st_mode))
 595                 return fd_copy_node(fdf, from, &st, fdt, to, override_uid, override_gid, copy_flags);
 596         else
 597                 return -EOPNOTSUPP;
 598 }
 599
 600 int copy_tree(const char *from, const char *to, uid_t override_uid, gid_t override_gid, CopyFlags copy_flags) {
 601         return copy_tree_at(AT_FDCWD, from, AT_FDCWD, to, override_uid, override_gid, copy_flags);
 602 }
 603
 604 int copy_directory_fd(int dirfd, const char *to, CopyFlags copy_flags) {
 605         struct stat st;
 606
 607         assert(dirfd >= 0);
 608         assert(to);
 609
 610         if (fstat(dirfd, &st) < 0)
 611                 return -errno;
 612
 613         if (!S_ISDIR(st.st_mode))
 614                 return -ENOTDIR;
 615
 616         return fd_copy_directory(dirfd, NULL, &st, AT_FDCWD, to, st.st_dev, UID_INVALID, GID_INVALID, copy_flags);
 617 }
 618
 619 int copy_directory(const char *from, const char *to, CopyFlags copy_flags) {
 620         struct stat st;
 621
 622         assert(from);
 623         assert(to);
 624
 625         if (lstat(from, &st) < 0)
 626                 return -errno;
 627
 628         if (!S_ISDIR(st.st_mode))
 629                 return -ENOTDIR;
 630
 631         return fd_copy_directory(AT_FDCWD, from, &st, AT_FDCWD, to, st.st_dev, UID_INVALID, GID_INVALID, copy_flags);
 632 }
 633
 634 int copy_file_fd(const char *from, int fdt, CopyFlags copy_flags) {
 635         _cleanup_close_ int fdf = -1;
 636         int r;
 637
 638         assert(from);
 639         assert(fdt >= 0);
 640
 641         fdf = open(from, O_RDONLY|O_CLOEXEC|O_NOCTTY);
 642         if (fdf < 0)
 643                 return -errno;
 644
 645         r = copy_bytes(fdf, fdt, (uint64_t) -1, copy_flags);
 646
 647         (void) copy_times(fdf, fdt);
 648         (void) copy_xattr(fdf, fdt);
 649
 650         return r;
 651 }
 652
 653 int copy_file(const char *from, const char *to, int flags, mode_t mode, unsigned chattr_flags, CopyFlags copy_flags) {
 654         int fdt = -1, r;
 655
 656         assert(from);
 657         assert(to);
 658
 659         RUN_WITH_UMASK(0000) {
 660                 fdt = open(to, flags|O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY, mode);
 661                 if (fdt < 0)
 662                         return -errno;
 663         }
 664
 665         if (chattr_flags != 0)
 666                 (void) chattr_fd(fdt, chattr_flags, (unsigned) -1);
 667
 668         r = copy_file_fd(from, fdt, copy_flags);
 669         if (r < 0) {
 670                 close(fdt);
 671                 (void) unlink(to);
 672                 return r;
 673         }
 674
 675         if (close(fdt) < 0) {
 676                 unlink_noerrno(to);
 677                 return -errno;
 678         }
 679
 680         return 0;
 681 }
 682
 683 int copy_file_atomic(const char *from, const char *to, mode_t mode, unsigned chattr_flags, CopyFlags copy_flags) {
 684         _cleanup_free_ char *t = NULL;
 685         int r;
 686
 687         assert(from);
 688         assert(to);
 689
 690         r = tempfn_random(to, NULL, &t);
 691         if (r < 0)
 692                 return r;
 693
 694         r = copy_file(from, t, O_NOFOLLOW|O_EXCL, mode, chattr_flags, copy_flags);
 695         if (r < 0)
 696                 return r;
 697
 698         if (copy_flags & COPY_REPLACE) {
 699                 r = renameat(AT_FDCWD, t, AT_FDCWD, to);
 700                 if (r < 0)
 701                         r = -errno;
 702         } else
 703                 r = rename_noreplace(AT_FDCWD, t, AT_FDCWD, to);
 704         if (r < 0) {
 705                 (void) unlink(t);
 706                 return r;
 707         }
 708
 709         return 0;
 710 }
 711
 712 int copy_times(int fdf, int fdt) {
 713         struct timespec ut[2];
 714         struct stat st;
 715         usec_t crtime = 0;
 716
 717         assert(fdf >= 0);
 718         assert(fdt >= 0);
 719
 720         if (fstat(fdf, &st) < 0)
 721                 return -errno;
 722
 723         ut[0] = st.st_atim;
 724         ut[1] = st.st_mtim;
 725
 726         if (futimens(fdt, ut) < 0)
 727                 return -errno;
 728
 729         if (fd_getcrtime(fdf, &crtime) >= 0)
 730                 (void) fd_setcrtime(fdt, crtime);
 731
 732         return 0;
 733 }
 734
 735 int copy_xattr(int fdf, int fdt) {
 736         _cleanup_free_ char *bufa = NULL, *bufb = NULL;
 737         size_t sza = 100, szb = 100;
 738         ssize_t n;
 739         int ret = 0;
 740         const char *p;
 741
 742         for (;;) {
 743                 bufa = malloc(sza);
 744                 if (!bufa)
 745                         return -ENOMEM;
 746
 747                 n = flistxattr(fdf, bufa, sza);
 748                 if (n == 0)
 749                         return 0;
 750                 if (n > 0)
 751                         break;
 752                 if (errno != ERANGE)
 753                         return -errno;
 754
 755                 sza *= 2;
 756
 757                 bufa = mfree(bufa);
 758         }
 759
 760         p = bufa;
 761         while (n > 0) {
 762                 size_t l;
 763
 764                 l = strlen(p);
 765                 assert(l < (size_t) n);
 766
 767                 if (startswith(p, "user.")) {
 768                         ssize_t m;
 769
 770                         if (!bufb) {
 771                                 bufb = malloc(szb);
 772                                 if (!bufb)
 773                                         return -ENOMEM;
 774                         }
 775
 776                         m = fgetxattr(fdf, p, bufb, szb);
 777                         if (m < 0) {
 778                                 if (errno == ERANGE) {
 779                                         szb *= 2;
 780                                         bufb = mfree(bufb);
 781                                         continue;
 782                                 }
 783
 784                                 return -errno;
 785                         }
 786
 787                         if (fsetxattr(fdt, p, bufb, m, 0) < 0)
 788                                 ret = -errno;
 789                 }
 790
 791                 p += l + 1;
 792                 n -= l + 1;
 793         }
 794
 795         return ret;
 796 }