syscall.c

   1 /*
   2  * Syscall wrappers to ensure that nothing gets done in dry_run mode
   3  * and to handle system peculiarities.
   4  *
   5  * Copyright (C) 1998 Andrew Tridgell
   6  * Copyright (C) 2002 Martin Pool
   7  * Copyright (C) 2003-2020 Wayne Davison
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 3 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, visit the http://fsf.org website.
  21  */
  22
  23 #include "rsync.h"
  24
  25 #if !defined MKNOD_CREATES_SOCKETS && defined HAVE_SYS_UN_H
  26 #include <sys/un.h>
  27 #endif
  28 #ifdef HAVE_SYS_ATTR_H
  29 #include <sys/attr.h>
  30 #endif
  31
  32 #if defined HAVE_SYS_FALLOCATE && !defined HAVE_FALLOCATE
  33 #include <sys/syscall.h>
  34 #endif
  35
  36 extern int dry_run;
  37 extern int am_root;
  38 extern int am_sender;
  39 extern int read_only;
  40 extern int list_only;
  41 extern int inplace;
  42 extern int preallocate_files;
  43 extern int preserve_perms;
  44 extern int preserve_executability;
  45 extern int open_noatime;
  46
  47 #ifndef S_BLKSIZE
  48 # if defined hpux || defined __hpux__ || defined __hpux
  49 #  define S_BLKSIZE 1024
  50 # elif defined _AIX && defined _I386
  51 #  define S_BLKSIZE 4096
  52 # else
  53 #  define S_BLKSIZE 512
  54 # endif
  55 #endif
  56
  57 #define RETURN_ERROR_IF(x,e) \
  58         do { \
  59                 if (x) { \
  60                         errno = (e); \
  61                         return -1; \
  62                 } \
  63         } while (0)
  64
  65 #define RETURN_ERROR_IF_RO_OR_LO RETURN_ERROR_IF(read_only || list_only, EROFS)
  66
  67 int do_unlink(const char *fname)
  68 {
  69         if (dry_run) return 0;
  70         RETURN_ERROR_IF_RO_OR_LO;
  71         return unlink(fname);
  72 }
  73
  74 #ifdef SUPPORT_LINKS
  75 int do_symlink(const char *lnk, const char *fname)
  76 {
  77         if (dry_run) return 0;
  78         RETURN_ERROR_IF_RO_OR_LO;
  79
  80 #if defined NO_SYMLINK_XATTRS || defined NO_SYMLINK_USER_XATTRS
  81         /* For --fake-super, we create a normal file with mode 0600
  82          * and write the lnk into it. */
  83         if (am_root < 0) {
  84                 int ok, len = strlen(lnk);
  85                 int fd = open(fname, O_WRONLY|O_CREAT|O_TRUNC, S_IWUSR|S_IRUSR);
  86                 if (fd < 0)
  87                         return -1;
  88                 ok = write(fd, lnk, len) == len;
  89                 if (close(fd) < 0)
  90                         ok = 0;
  91                 return ok ? 0 : -1;
  92         }
  93 #endif
  94
  95         return symlink(lnk, fname);
  96 }
  97
  98 #if defined NO_SYMLINK_XATTRS || defined NO_SYMLINK_USER_XATTRS
  99 ssize_t do_readlink(const char *path, char *buf, size_t bufsiz)
 100 {
 101         /* For --fake-super, we read the link from the file. */
 102         if (am_root < 0) {
 103                 int fd = do_open_nofollow(path, O_RDONLY);
 104                 if (fd >= 0) {
 105                         int len = read(fd, buf, bufsiz);
 106                         close(fd);
 107                         return len;
 108                 }
 109                 if (errno != ELOOP)
 110                         return -1;
 111                 /* A real symlink needs to be turned into a fake one on the receiving
 112                  * side, so tell the generator that the link has no length. */
 113                 if (!am_sender)
 114                         return 0;
 115                 /* Otherwise fall through and let the sender report the real length. */
 116         }
 117
 118         return readlink(path, buf, bufsiz);
 119 }
 120 #endif
 121 #endif
 122
 123 #ifdef HAVE_LINK
 124 int do_link(const char *old_path, const char *new_path)
 125 {
 126         if (dry_run) return 0;
 127         RETURN_ERROR_IF_RO_OR_LO;
 128         return link(old_path, new_path);
 129 }
 130 #endif
 131
 132 int do_lchown(const char *path, uid_t owner, gid_t group)
 133 {
 134         if (dry_run) return 0;
 135         RETURN_ERROR_IF_RO_OR_LO;
 136 #ifndef HAVE_LCHOWN
 137 #define lchown chown
 138 #endif
 139         return lchown(path, owner, group);
 140 }
 141
 142 int do_mknod(const char *pathname, mode_t mode, dev_t dev)
 143 {
 144         if (dry_run) return 0;
 145         RETURN_ERROR_IF_RO_OR_LO;
 146
 147         /* For --fake-super, we create a normal file with mode 0600. */
 148         if (am_root < 0) {
 149                 int fd = open(pathname, O_WRONLY|O_CREAT|O_TRUNC, S_IWUSR|S_IRUSR);
 150                 if (fd < 0 || close(fd) < 0)
 151                         return -1;
 152                 return 0;
 153         }
 154
 155 #if !defined MKNOD_CREATES_FIFOS && defined HAVE_MKFIFO
 156         if (S_ISFIFO(mode))
 157                 return mkfifo(pathname, mode);
 158 #endif
 159 #if !defined MKNOD_CREATES_SOCKETS && defined HAVE_SYS_UN_H
 160         if (S_ISSOCK(mode)) {
 161                 int sock;
 162                 struct sockaddr_un saddr;
 163                 unsigned int len = strlcpy(saddr.sun_path, pathname, sizeof saddr.sun_path);
 164                 if (len >= sizeof saddr.sun_path) {
 165                         errno = ENAMETOOLONG;
 166                         return -1;
 167                 }
 168 #ifdef HAVE_SOCKADDR_UN_LEN
 169                 saddr.sun_len = len + 1;
 170 #endif
 171                 saddr.sun_family = AF_UNIX;
 172
 173                 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0
 174                  || (unlink(pathname) < 0 && errno != ENOENT)
 175                  || (bind(sock, (struct sockaddr*)&saddr, sizeof saddr)) < 0)
 176                         return -1;
 177                 close(sock);
 178 #ifdef HAVE_CHMOD
 179                 return do_chmod(pathname, mode);
 180 #else
 181                 return 0;
 182 #endif
 183         }
 184 #endif
 185 #ifdef HAVE_MKNOD
 186         return mknod(pathname, mode, dev);
 187 #else
 188         return -1;
 189 #endif
 190 }
 191
 192 int do_rmdir(const char *pathname)
 193 {
 194         if (dry_run) return 0;
 195         RETURN_ERROR_IF_RO_OR_LO;
 196         return rmdir(pathname);
 197 }
 198
 199 int do_open(const char *pathname, int flags, mode_t mode)
 200 {
 201         if (flags != O_RDONLY) {
 202                 RETURN_ERROR_IF(dry_run, 0);
 203                 RETURN_ERROR_IF_RO_OR_LO;
 204         }
 205
 206 #ifdef O_NOATIME
 207         if (open_noatime)
 208                 flags |= O_NOATIME;
 209 #endif
 210
 211         return open(pathname, flags | O_BINARY, mode);
 212 }
 213
 214 #ifdef HAVE_CHMOD
 215 int do_chmod(const char *path, mode_t mode)
 216 {
 217         int code;
 218         if (dry_run) return 0;
 219         RETURN_ERROR_IF_RO_OR_LO;
 220 #ifdef HAVE_LCHMOD
 221         code = lchmod(path, mode & CHMOD_BITS);
 222 #else
 223         if (S_ISLNK(mode)) {
 224 # if defined HAVE_SETATTRLIST
 225                 struct attrlist attrList;
 226                 uint32_t m = mode & CHMOD_BITS; /* manpage is wrong: not mode_t! */
 227
 228                 memset(&attrList, 0, sizeof attrList);
 229                 attrList.bitmapcount = ATTR_BIT_MAP_COUNT;
 230                 attrList.commonattr = ATTR_CMN_ACCESSMASK;
 231                 code = setattrlist(path, &attrList, &m, sizeof m, FSOPT_NOFOLLOW);
 232 # else
 233                 code = 1;
 234 # endif
 235         } else
 236                 code = chmod(path, mode & CHMOD_BITS); /* DISCOURAGED FUNCTION */
 237 #endif /* !HAVE_LCHMOD */
 238         if (code != 0 && (preserve_perms || preserve_executability))
 239                 return code;
 240         return 0;
 241 }
 242 #endif
 243
 244 int do_rename(const char *old_path, const char *new_path)
 245 {
 246         if (dry_run) return 0;
 247         RETURN_ERROR_IF_RO_OR_LO;
 248         return rename(old_path, new_path);
 249 }
 250
 251 #ifdef HAVE_FTRUNCATE
 252 int do_ftruncate(int fd, OFF_T size)
 253 {
 254         int ret;
 255
 256         if (dry_run) return 0;
 257         RETURN_ERROR_IF_RO_OR_LO;
 258
 259         do {
 260                 ret = ftruncate(fd, size);
 261         } while (ret < 0 && errno == EINTR);
 262
 263         return ret;
 264 }
 265 #endif
 266
 267 void trim_trailing_slashes(char *name)
 268 {
 269         int l;
 270         /* Some BSD systems cannot make a directory if the name
 271          * contains a trailing slash.
 272          * <http://www.opensource.apple.com/bugs/X/BSD%20Kernel/2734739.html> */
 273
 274         /* Don't change empty string; and also we can't improve on
 275          * "/" */
 276
 277         l = strlen(name);
 278         while (l > 1) {
 279                 if (name[--l] != '/')
 280                         break;
 281                 name[l] = '\0';
 282         }
 283 }
 284
 285 int do_mkdir(char *fname, mode_t mode)
 286 {
 287         if (dry_run) return 0;
 288         RETURN_ERROR_IF_RO_OR_LO;
 289         trim_trailing_slashes(fname);
 290         return mkdir(fname, mode);
 291 }
 292
 293 /* like mkstemp but forces permissions */
 294 int do_mkstemp(char *template, mode_t perms)
 295 {
 296         RETURN_ERROR_IF(dry_run, 0);
 297         RETURN_ERROR_IF(read_only, EROFS);
 298         perms |= S_IWUSR;
 299
 300 #if defined HAVE_SECURE_MKSTEMP && defined HAVE_FCHMOD && (!defined HAVE_OPEN64 || defined HAVE_MKSTEMP64)
 301         {
 302                 int fd = mkstemp(template);
 303                 if (fd == -1)
 304                         return -1;
 305                 if (fchmod(fd, perms) != 0 && preserve_perms) {
 306                         int errno_save = errno;
 307                         close(fd);
 308                         unlink(template);
 309                         errno = errno_save;
 310                         return -1;
 311                 }
 312 #if defined HAVE_SETMODE && O_BINARY
 313                 setmode(fd, O_BINARY);
 314 #endif
 315                 return fd;
 316         }
 317 #else
 318         if (!mktemp(template))
 319                 return -1;
 320         return do_open(template, O_RDWR|O_EXCL|O_CREAT, perms);
 321 #endif
 322 }
 323
 324 int do_stat(const char *fname, STRUCT_STAT *st)
 325 {
 326 #ifdef USE_STAT64_FUNCS
 327         return stat64(fname, st);
 328 #else
 329         return stat(fname, st);
 330 #endif
 331 }
 332
 333 int do_lstat(const char *fname, STRUCT_STAT *st)
 334 {
 335 #ifdef SUPPORT_LINKS
 336 # ifdef USE_STAT64_FUNCS
 337         return lstat64(fname, st);
 338 # else
 339         return lstat(fname, st);
 340 # endif
 341 #else
 342         return do_stat(fname, st);
 343 #endif
 344 }
 345
 346 int do_fstat(int fd, STRUCT_STAT *st)
 347 {
 348 #ifdef USE_STAT64_FUNCS
 349         return fstat64(fd, st);
 350 #else
 351         return fstat(fd, st);
 352 #endif
 353 }
 354
 355 OFF_T do_lseek(int fd, OFF_T offset, int whence)
 356 {
 357 #ifdef HAVE_LSEEK64
 358 #if !SIZEOF_OFF64_T
 359         OFF_T lseek64();
 360 #else
 361         off64_t lseek64();
 362 #endif
 363         return lseek64(fd, offset, whence);
 364 #else
 365         return lseek(fd, offset, whence);
 366 #endif
 367 }
 368
 369 #ifdef HAVE_SETATTRLIST
 370 int do_setattrlist_times(const char *fname, STRUCT_STAT *stp)
 371 {
 372         struct attrlist attrList;
 373         struct timespec ts;
 374
 375         if (dry_run) return 0;
 376         RETURN_ERROR_IF_RO_OR_LO;
 377
 378         ts.tv_sec = stp->st_mtime;
 379         ts.tv_nsec = stp->ST_MTIME_NSEC;
 380
 381         memset(&attrList, 0, sizeof attrList);
 382         attrList.bitmapcount = ATTR_BIT_MAP_COUNT;
 383         attrList.commonattr = ATTR_CMN_MODTIME;
 384         return setattrlist(fname, &attrList, &ts, sizeof ts, FSOPT_NOFOLLOW);
 385 }
 386 #endif
 387
 388 #ifdef HAVE_UTIMENSAT
 389 int do_utimensat(const char *fname, STRUCT_STAT *stp)
 390 {
 391         struct timespec t[2];
 392
 393         if (dry_run) return 0;
 394         RETURN_ERROR_IF_RO_OR_LO;
 395
 396         t[0].tv_sec = stp->st_atime;
 397 #ifdef ST_ATIME_NSEC
 398         t[0].tv_nsec = stp->ST_ATIME_NSEC;
 399 #else
 400         t[0].tv_nsec = 0;
 401 #endif
 402         t[1].tv_sec = stp->st_mtime;
 403 #ifdef ST_MTIME_NSEC
 404         t[1].tv_nsec = stp->ST_MTIME_NSEC;
 405 #else
 406         t[1].tv_nsec = 0;
 407 #endif
 408         return utimensat(AT_FDCWD, fname, t, AT_SYMLINK_NOFOLLOW);
 409 }
 410 #endif
 411
 412 #ifdef HAVE_LUTIMES
 413 int do_lutimes(const char *fname, STRUCT_STAT *stp)
 414 {
 415         struct timeval t[2];
 416
 417         if (dry_run) return 0;
 418         RETURN_ERROR_IF_RO_OR_LO;
 419
 420         t[0].tv_sec = stp->st_atime;
 421 #ifdef ST_ATIME_NSEC
 422         t[0].tv_usec = stp->ST_ATIME_NSEC / 1000;
 423 #else
 424         t[0].tv_usec = 0;
 425 #endif
 426         t[1].tv_sec = stp->st_mtime;
 427 #ifdef ST_MTIME_NSEC
 428         t[1].tv_usec = stp->ST_MTIME_NSEC / 1000;
 429 #else
 430         t[1].tv_usec = 0;
 431 #endif
 432         return lutimes(fname, t);
 433 }
 434 #endif
 435
 436 #ifdef HAVE_UTIMES
 437 int do_utimes(const char *fname, STRUCT_STAT *stp)
 438 {
 439         struct timeval t[2];
 440
 441         if (dry_run) return 0;
 442         RETURN_ERROR_IF_RO_OR_LO;
 443
 444         t[0].tv_sec = stp->st_atime;
 445 #ifdef ST_ATIME_NSEC
 446         t[0].tv_usec = stp->ST_ATIME_NSEC / 1000;
 447 #else
 448         t[0].tv_usec = 0;
 449 #endif
 450         t[1].tv_sec = stp->st_mtime;
 451 #ifdef ST_MTIME_NSEC
 452         t[1].tv_usec = stp->ST_MTIME_NSEC / 1000;
 453 #else
 454         t[1].tv_usec = 0;
 455 #endif
 456         return utimes(fname, t);
 457 }
 458
 459 #elif defined HAVE_UTIME
 460 int do_utime(const char *fname, STRUCT_STAT *stp)
 461 {
 462 #ifdef HAVE_STRUCT_UTIMBUF
 463         struct utimbuf tbuf;
 464 #else
 465         time_t t[2];
 466 #endif
 467
 468         if (dry_run) return 0;
 469         RETURN_ERROR_IF_RO_OR_LO;
 470
 471 # ifdef HAVE_STRUCT_UTIMBUF
 472         tbuf.actime = stp->st_atime;
 473         tbuf.modtime = stp->st_mtime;
 474         return utime(fname, &tbuf);
 475 # else
 476         t[0] = stp->st_atime;
 477         t[1] = stp->st_mtime;
 478         return utime(fname, t);
 479 # endif
 480 }
 481
 482 #else
 483 #error Need utimes or utime function.
 484 #endif
 485
 486 #ifdef SUPPORT_PREALLOCATION
 487 #ifdef FALLOC_FL_KEEP_SIZE
 488 #define DO_FALLOC_OPTIONS FALLOC_FL_KEEP_SIZE
 489 #else
 490 #define DO_FALLOC_OPTIONS 0
 491 #endif
 492
 493 OFF_T do_fallocate(int fd, OFF_T offset, OFF_T length)
 494 {
 495         int opts = inplace || preallocate_files ? DO_FALLOC_OPTIONS : 0;
 496         int ret;
 497         RETURN_ERROR_IF(dry_run, 0);
 498         RETURN_ERROR_IF_RO_OR_LO;
 499         if (length & 1) /* make the length not match the desired length */
 500                 length++;
 501         else
 502                 length--;
 503 #if defined HAVE_FALLOCATE
 504         ret = fallocate(fd, opts, offset, length);
 505 #elif defined HAVE_SYS_FALLOCATE
 506         ret = syscall(SYS_fallocate, fd, opts, (loff_t)offset, (loff_t)length);
 507 #elif defined HAVE_EFFICIENT_POSIX_FALLOCATE
 508         ret = posix_fallocate(fd, offset, length);
 509 #else
 510 #error Coding error in SUPPORT_PREALLOCATION logic.
 511 #endif
 512         if (ret < 0)
 513                 return ret;
 514         if (opts == 0) {
 515                 STRUCT_STAT st;
 516                 if (do_fstat(fd, &st) < 0)
 517                         return length;
 518                 return st.st_blocks * S_BLKSIZE;
 519         }
 520         return 0;
 521 }
 522 #endif
 523
 524 /* Punch a hole at pos for len bytes. The current file position must be at pos and will be
 525  * changed to be at pos + len. */
 526 int do_punch_hole(int fd, UNUSED(OFF_T pos), OFF_T len)
 527 {
 528 #ifdef HAVE_FALLOCATE
 529 # ifdef HAVE_FALLOC_FL_PUNCH_HOLE
 530         if (fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, pos, len) == 0) {
 531                 if (do_lseek(fd, len, SEEK_CUR) != pos + len)
 532                         return -1;
 533                 return 0;
 534         }
 535 # endif
 536 # ifdef HAVE_FALLOC_FL_ZERO_RANGE
 537         if (fallocate(fd, FALLOC_FL_ZERO_RANGE, pos, len) == 0) {
 538                 if (do_lseek(fd, len, SEEK_CUR) != pos + len)
 539                         return -1;
 540                 return 0;
 541         }
 542 # endif
 543 #endif
 544         {
 545                 char zeros[4096];
 546                 memset(zeros, 0, sizeof zeros);
 547                 while (len > 0) {
 548                         int chunk = len > (int)sizeof zeros ? (int)sizeof zeros : len;
 549                         int wrote = write(fd, zeros, chunk);
 550                         if (wrote <= 0) {
 551                                 if (wrote < 0 && errno == EINTR)
 552                                         continue;
 553                                 return -1;
 554                         }
 555                         len -= wrote;
 556                 }
 557         }
 558         return 0;
 559 }
 560
 561 int do_open_nofollow(const char *pathname, int flags)
 562 {
 563 #ifndef O_NOFOLLOW
 564         STRUCT_STAT f_st, l_st;
 565 #endif
 566         int fd;
 567
 568         if (flags != O_RDONLY) {
 569                 RETURN_ERROR_IF(dry_run, 0);
 570                 RETURN_ERROR_IF_RO_OR_LO;
 571 #ifndef O_NOFOLLOW
 572                 /* This function doesn't support write attempts w/o O_NOFOLLOW. */
 573                 errno = EINVAL;
 574                 return -1;
 575 #endif
 576         }
 577
 578 #ifdef O_NOFOLLOW
 579         fd = open(pathname, flags|O_NOFOLLOW);
 580 #else
 581         if (do_lstat(pathname, &l_st) < 0)
 582                 return -1;
 583         if (S_ISLNK(l_st.st_mode)) {
 584                 errno = ELOOP;
 585                 return -1;
 586         }
 587         if ((fd = open(pathname, flags)) < 0)
 588                 return fd;
 589         if (do_fstat(fd, &f_st) < 0) {
 590           close_and_return_error:
 591                 {
 592                         int save_errno = errno;
 593                         close(fd);
 594                         errno = save_errno;
 595                 }
 596                 return -1;
 597         }
 598         if (l_st.st_dev != f_st.st_dev || l_st.st_ino != f_st.st_ino) {
 599                 errno = EINVAL;
 600                 goto close_and_return_error;
 601         }
 602 #endif
 603
 604         return fd;
 605 }