src/basic/copy.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2014 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <dirent.h>
  21 #include <errno.h>
  22 #include <fcntl.h>
  23 #include <stddef.h>
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <sys/sendfile.h>
  28 #include <sys/stat.h>
  29 #include <sys/xattr.h>
  30 #include <time.h>
  31 #include <unistd.h>
  32
  33 #include "alloc-util.h"
  34 #include "btrfs-util.h"
  35 #include "chattr-util.h"
  36 #include "copy.h"
  37 #include "dirent-util.h"
  38 #include "fd-util.h"
  39 #include "fileio.h"
  40 #include "fs-util.h"
  41 #include "io-util.h"
  42 #include "macro.h"
  43 #include "missing.h"
  44 #include "string-util.h"
  45 #include "strv.h"
  46 #include "time-util.h"
  47 #include "umask-util.h"
  48 #include "xattr-util.h"
  49
  50 #define COPY_BUFFER_SIZE (16*1024u)
  51
  52 static ssize_t try_copy_file_range(int fd_in, loff_t *off_in,
  53                                    int fd_out, loff_t *off_out,
  54                                    size_t len,
  55                                    unsigned int flags) {
  56         static int have = -1;
  57         ssize_t r;
  58
  59         if (have == false)
  60                 return -ENOSYS;
  61
  62         r = copy_file_range(fd_in, off_in, fd_out, off_out, len, flags);
  63         if (_unlikely_(have < 0))
  64                 have = r >= 0 || errno != ENOSYS;
  65         if (r >= 0)
  66                 return r;
  67         else
  68                 return -errno;
  69 }
  70
  71 int copy_bytes(int fdf, int fdt, uint64_t max_bytes, bool try_reflink) {
  72         bool try_cfr = true, try_sendfile = true, try_splice = true;
  73         int r;
  74         size_t m = SSIZE_MAX; /* that is the maximum that sendfile and c_f_r accept */
  75
  76         assert(fdf >= 0);
  77         assert(fdt >= 0);
  78
  79         /* Try btrfs reflinks first. */
  80         if (try_reflink &&
  81             max_bytes == (uint64_t) -1 &&
  82             lseek(fdf, 0, SEEK_CUR) == 0 &&
  83             lseek(fdt, 0, SEEK_CUR) == 0) {
  84
  85                 r = btrfs_reflink(fdf, fdt);
  86                 if (r >= 0)
  87                         return 0; /* we copied the whole thing, hence hit EOF, return 0 */
  88         }
  89
  90         for (;;) {
  91                 ssize_t n;
  92
  93                 if (max_bytes != (uint64_t) -1) {
  94                         if (max_bytes <= 0)
  95                                 return 1; /* return > 0 if we hit the max_bytes limit */
  96
  97                         if (m > max_bytes)
  98                                 m = max_bytes;
  99                 }
 100
 101                 /* First try copy_file_range(), unless we already tried */
 102                 if (try_cfr) {
 103                         n = try_copy_file_range(fdf, NULL, fdt, NULL, m, 0u);
 104                         if (n < 0) {
 105                                 if (!IN_SET(n, -EINVAL, -ENOSYS, -EXDEV, -EBADF))
 106                                         return n;
 107
 108                                 try_cfr = false;
 109                                 /* use fallback below */
 110                         } else if (n == 0) /* EOF */
 111                                 break;
 112                         else
 113                                 /* Success! */
 114                                 goto next;
 115                 }
 116
 117                 /* First try sendfile(), unless we already tried */
 118                 if (try_sendfile) {
 119                         n = sendfile(fdt, fdf, NULL, m);
 120                         if (n < 0) {
 121                                 if (!IN_SET(errno, EINVAL, ENOSYS))
 122                                         return -errno;
 123
 124                                 try_sendfile = false;
 125                                 /* use fallback below */
 126                         } else if (n == 0) /* EOF */
 127                                 break;
 128                         else
 129                                 /* Success! */
 130                                 goto next;
 131                 }
 132
 133                 /* Then try splice, unless we already tried */
 134                 if (try_splice) {
 135                         n = splice(fdf, NULL, fdt, NULL, m, 0);
 136                         if (n < 0) {
 137                                 if (!IN_SET(errno, EINVAL, ENOSYS))
 138                                         return -errno;
 139
 140                                 try_splice = false;
 141                                 /* use fallback below */
 142                         } else if (n == 0) /* EOF */
 143                                 break;
 144                         else
 145                                 /* Success! */
 146                                 goto next;
 147                 }
 148
 149                 /* As a fallback just copy bits by hand */
 150                 {
 151                         uint8_t buf[MIN(m, COPY_BUFFER_SIZE)];
 152
 153                         n = read(fdf, buf, sizeof buf);
 154                         if (n < 0)
 155                                 return -errno;
 156                         if (n == 0) /* EOF */
 157                                 break;
 158
 159                         r = loop_write(fdt, buf, (size_t) n, false);
 160                         if (r < 0)
 161                                 return r;
 162                 }
 163
 164         next:
 165                 if (max_bytes != (uint64_t) -1) {
 166                         assert(max_bytes >= (uint64_t) n);
 167                         max_bytes -= n;
 168                 }
 169                 /* sendfile accepts at most SSIZE_MAX-offset bytes to copy,
 170                  * so reduce our maximum by the amount we already copied,
 171                  * but don't go below our copy buffer size, unless we are
 172                  * close the the limit of bytes we are allowed to copy. */
 173                 m = MAX(MIN(COPY_BUFFER_SIZE, max_bytes), m - n);
 174         }
 175
 176         return 0; /* return 0 if we hit EOF earlier than the size limit */
 177 }
 178
 179 static int fd_copy_symlink(int df, const char *from, const struct stat *st, int dt, const char *to) {
 180         _cleanup_free_ char *target = NULL;
 181         int r;
 182
 183         assert(from);
 184         assert(st);
 185         assert(to);
 186
 187         r = readlinkat_malloc(df, from, &target);
 188         if (r < 0)
 189                 return r;
 190
 191         if (symlinkat(target, dt, to) < 0)
 192                 return -errno;
 193
 194         if (fchownat(dt, to, st->st_uid, st->st_gid, AT_SYMLINK_NOFOLLOW) < 0)
 195                 return -errno;
 196
 197         return 0;
 198 }
 199
 200 static int fd_copy_regular(int df, const char *from, const struct stat *st, int dt, const char *to) {
 201         _cleanup_close_ int fdf = -1, fdt = -1;
 202         struct timespec ts[2];
 203         int r, q;
 204
 205         assert(from);
 206         assert(st);
 207         assert(to);
 208
 209         fdf = openat(df, from, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
 210         if (fdf < 0)
 211                 return -errno;
 212
 213         fdt = openat(dt, to, O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, st->st_mode & 07777);
 214         if (fdt < 0)
 215                 return -errno;
 216
 217         r = copy_bytes(fdf, fdt, (uint64_t) -1, true);
 218         if (r < 0) {
 219                 unlinkat(dt, to, 0);
 220                 return r;
 221         }
 222
 223         if (fchown(fdt, st->st_uid, st->st_gid) < 0)
 224                 r = -errno;
 225
 226         if (fchmod(fdt, st->st_mode & 07777) < 0)
 227                 r = -errno;
 228
 229         ts[0] = st->st_atim;
 230         ts[1] = st->st_mtim;
 231         (void) futimens(fdt, ts);
 232
 233         (void) copy_xattr(fdf, fdt);
 234
 235         q = close(fdt);
 236         fdt = -1;
 237
 238         if (q < 0) {
 239                 r = -errno;
 240                 unlinkat(dt, to, 0);
 241         }
 242
 243         return r;
 244 }
 245
 246 static int fd_copy_fifo(int df, const char *from, const struct stat *st, int dt, const char *to) {
 247         int r;
 248
 249         assert(from);
 250         assert(st);
 251         assert(to);
 252
 253         r = mkfifoat(dt, to, st->st_mode & 07777);
 254         if (r < 0)
 255                 return -errno;
 256
 257         if (fchownat(dt, to, st->st_uid, st->st_gid, AT_SYMLINK_NOFOLLOW) < 0)
 258                 r = -errno;
 259
 260         if (fchmodat(dt, to, st->st_mode & 07777, 0) < 0)
 261                 r = -errno;
 262
 263         return r;
 264 }
 265
 266 static int fd_copy_node(int df, const char *from, const struct stat *st, int dt, const char *to) {
 267         int r;
 268
 269         assert(from);
 270         assert(st);
 271         assert(to);
 272
 273         r = mknodat(dt, to, st->st_mode, st->st_rdev);
 274         if (r < 0)
 275                 return -errno;
 276
 277         if (fchownat(dt, to, st->st_uid, st->st_gid, AT_SYMLINK_NOFOLLOW) < 0)
 278                 r = -errno;
 279
 280         if (fchmodat(dt, to, st->st_mode & 07777, 0) < 0)
 281                 r = -errno;
 282
 283         return r;
 284 }
 285
 286 static int fd_copy_directory(
 287                 int df,
 288                 const char *from,
 289                 const struct stat *st,
 290                 int dt,
 291                 const char *to,
 292                 dev_t original_device,
 293                 bool merge) {
 294
 295         _cleanup_close_ int fdf = -1, fdt = -1;
 296         _cleanup_closedir_ DIR *d = NULL;
 297         struct dirent *de;
 298         bool created;
 299         int r;
 300
 301         assert(st);
 302         assert(to);
 303
 304         if (from)
 305                 fdf = openat(df, from, O_RDONLY|O_DIRECTORY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
 306         else
 307                 fdf = fcntl(df, F_DUPFD_CLOEXEC, 3);
 308         if (fdf < 0)
 309                 return -errno;
 310
 311         d = fdopendir(fdf);
 312         if (!d)
 313                 return -errno;
 314         fdf = -1;
 315
 316         r = mkdirat(dt, to, st->st_mode & 07777);
 317         if (r >= 0)
 318                 created = true;
 319         else if (errno == EEXIST && merge)
 320                 created = false;
 321         else
 322                 return -errno;
 323
 324         fdt = openat(dt, to, O_RDONLY|O_DIRECTORY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
 325         if (fdt < 0)
 326                 return -errno;
 327
 328         r = 0;
 329
 330         if (created) {
 331                 struct timespec ut[2] = {
 332                         st->st_atim,
 333                         st->st_mtim
 334                 };
 335
 336                 if (fchown(fdt, st->st_uid, st->st_gid) < 0)
 337                         r = -errno;
 338
 339                 if (fchmod(fdt, st->st_mode & 07777) < 0)
 340                         r = -errno;
 341
 342                 (void) futimens(fdt, ut);
 343                 (void) copy_xattr(dirfd(d), fdt);
 344         }
 345
 346         FOREACH_DIRENT_ALL(de, d, return -errno) {
 347                 struct stat buf;
 348                 int q;
 349
 350                 if (STR_IN_SET(de->d_name, ".", ".."))
 351                         continue;
 352
 353                 if (fstatat(dirfd(d), de->d_name, &buf, AT_SYMLINK_NOFOLLOW) < 0) {
 354                         r = -errno;
 355                         continue;
 356                 }
 357
 358                 if (buf.st_dev != original_device)
 359                         continue;
 360
 361                 if (S_ISREG(buf.st_mode))
 362                         q = fd_copy_regular(dirfd(d), de->d_name, &buf, fdt, de->d_name);
 363                 else if (S_ISDIR(buf.st_mode))
 364                         q = fd_copy_directory(dirfd(d), de->d_name, &buf, fdt, de->d_name, original_device, merge);
 365                 else if (S_ISLNK(buf.st_mode))
 366                         q = fd_copy_symlink(dirfd(d), de->d_name, &buf, fdt, de->d_name);
 367                 else if (S_ISFIFO(buf.st_mode))
 368                         q = fd_copy_fifo(dirfd(d), de->d_name, &buf, fdt, de->d_name);
 369                 else if (S_ISBLK(buf.st_mode) || S_ISCHR(buf.st_mode) || S_ISSOCK(buf.st_mode))
 370                         q = fd_copy_node(dirfd(d), de->d_name, &buf, fdt, de->d_name);
 371                 else
 372                         q = -EOPNOTSUPP;
 373
 374                 if (q == -EEXIST && merge)
 375                         q = 0;
 376
 377                 if (q < 0)
 378                         r = q;
 379         }
 380
 381         return r;
 382 }
 383
 384 int copy_tree_at(int fdf, const char *from, int fdt, const char *to, bool merge) {
 385         struct stat st;
 386
 387         assert(from);
 388         assert(to);
 389
 390         if (fstatat(fdf, from, &st, AT_SYMLINK_NOFOLLOW) < 0)
 391                 return -errno;
 392
 393         if (S_ISREG(st.st_mode))
 394                 return fd_copy_regular(fdf, from, &st, fdt, to);
 395         else if (S_ISDIR(st.st_mode))
 396                 return fd_copy_directory(fdf, from, &st, fdt, to, st.st_dev, merge);
 397         else if (S_ISLNK(st.st_mode))
 398                 return fd_copy_symlink(fdf, from, &st, fdt, to);
 399         else if (S_ISFIFO(st.st_mode))
 400                 return fd_copy_fifo(fdf, from, &st, fdt, to);
 401         else if (S_ISBLK(st.st_mode) || S_ISCHR(st.st_mode) || S_ISSOCK(st.st_mode))
 402                 return fd_copy_node(fdf, from, &st, fdt, to);
 403         else
 404                 return -EOPNOTSUPP;
 405 }
 406
 407 int copy_tree(const char *from, const char *to, bool merge) {
 408         return copy_tree_at(AT_FDCWD, from, AT_FDCWD, to, merge);
 409 }
 410
 411 int copy_directory_fd(int dirfd, const char *to, bool merge) {
 412
 413         struct stat st;
 414
 415         assert(dirfd >= 0);
 416         assert(to);
 417
 418         if (fstat(dirfd, &st) < 0)
 419                 return -errno;
 420
 421         if (!S_ISDIR(st.st_mode))
 422                 return -ENOTDIR;
 423
 424         return fd_copy_directory(dirfd, NULL, &st, AT_FDCWD, to, st.st_dev, merge);
 425 }
 426
 427 int copy_file_fd(const char *from, int fdt, bool try_reflink) {
 428         _cleanup_close_ int fdf = -1;
 429         int r;
 430
 431         assert(from);
 432         assert(fdt >= 0);
 433
 434         fdf = open(from, O_RDONLY|O_CLOEXEC|O_NOCTTY);
 435         if (fdf < 0)
 436                 return -errno;
 437
 438         r = copy_bytes(fdf, fdt, (uint64_t) -1, try_reflink);
 439
 440         (void) copy_times(fdf, fdt);
 441         (void) copy_xattr(fdf, fdt);
 442
 443         return r;
 444 }
 445
 446 int copy_file(const char *from, const char *to, int flags, mode_t mode, unsigned chattr_flags) {
 447         int fdt = -1, r;
 448
 449         assert(from);
 450         assert(to);
 451
 452         RUN_WITH_UMASK(0000) {
 453                 fdt = open(to, flags|O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY, mode);
 454                 if (fdt < 0)
 455                         return -errno;
 456         }
 457
 458         if (chattr_flags != 0)
 459                 (void) chattr_fd(fdt, chattr_flags, (unsigned) -1);
 460
 461         r = copy_file_fd(from, fdt, true);
 462         if (r < 0) {
 463                 close(fdt);
 464                 unlink(to);
 465                 return r;
 466         }
 467
 468         if (close(fdt) < 0) {
 469                 unlink_noerrno(to);
 470                 return -errno;
 471         }
 472
 473         return 0;
 474 }
 475
 476 int copy_file_atomic(const char *from, const char *to, mode_t mode, bool replace, unsigned chattr_flags) {
 477         _cleanup_free_ char *t = NULL;
 478         int r;
 479
 480         assert(from);
 481         assert(to);
 482
 483         r = tempfn_random(to, NULL, &t);
 484         if (r < 0)
 485                 return r;
 486
 487         r = copy_file(from, t, O_NOFOLLOW|O_EXCL, mode, chattr_flags);
 488         if (r < 0)
 489                 return r;
 490
 491         if (replace) {
 492                 r = renameat(AT_FDCWD, t, AT_FDCWD, to);
 493                 if (r < 0)
 494                         r = -errno;
 495         } else
 496                 r = rename_noreplace(AT_FDCWD, t, AT_FDCWD, to);
 497         if (r < 0) {
 498                 (void) unlink_noerrno(t);
 499                 return r;
 500         }
 501
 502         return 0;
 503 }
 504
 505 int copy_times(int fdf, int fdt) {
 506         struct timespec ut[2];
 507         struct stat st;
 508         usec_t crtime = 0;
 509
 510         assert(fdf >= 0);
 511         assert(fdt >= 0);
 512
 513         if (fstat(fdf, &st) < 0)
 514                 return -errno;
 515
 516         ut[0] = st.st_atim;
 517         ut[1] = st.st_mtim;
 518
 519         if (futimens(fdt, ut) < 0)
 520                 return -errno;
 521
 522         if (fd_getcrtime(fdf, &crtime) >= 0)
 523                 (void) fd_setcrtime(fdt, crtime);
 524
 525         return 0;
 526 }
 527
 528 int copy_xattr(int fdf, int fdt) {
 529         _cleanup_free_ char *bufa = NULL, *bufb = NULL;
 530         size_t sza = 100, szb = 100;
 531         ssize_t n;
 532         int ret = 0;
 533         const char *p;
 534
 535         for (;;) {
 536                 bufa = malloc(sza);
 537                 if (!bufa)
 538                         return -ENOMEM;
 539
 540                 n = flistxattr(fdf, bufa, sza);
 541                 if (n == 0)
 542                         return 0;
 543                 if (n > 0)
 544                         break;
 545                 if (errno != ERANGE)
 546                         return -errno;
 547
 548                 sza *= 2;
 549
 550                 bufa = mfree(bufa);
 551         }
 552
 553         p = bufa;
 554         while (n > 0) {
 555                 size_t l;
 556
 557                 l = strlen(p);
 558                 assert(l < (size_t) n);
 559
 560                 if (startswith(p, "user.")) {
 561                         ssize_t m;
 562
 563                         if (!bufb) {
 564                                 bufb = malloc(szb);
 565                                 if (!bufb)
 566                                         return -ENOMEM;
 567                         }
 568
 569                         m = fgetxattr(fdf, p, bufb, szb);
 570                         if (m < 0) {
 571                                 if (errno == ERANGE) {
 572                                         szb *= 2;
 573                                         bufb = mfree(bufb);
 574                                         continue;
 575                                 }
 576
 577                                 return -errno;
 578                         }
 579
 580                         if (fsetxattr(fdt, p, bufb, m, 0) < 0)
 581                                 ret = -errno;
 582                 }
 583
 584                 p += l + 1;
 585                 n -= l + 1;
 586         }
 587
 588         return ret;
 589 }