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