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) 2003-2014 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 preserve_perms;
  42 extern int preserve_executability;
  43
  44 #define RETURN_ERROR_IF(x,e) \
  45         do { \
  46                 if (x) { \
  47                         errno = (e); \
  48                         return -1; \
  49                 } \
  50         } while (0)
  51
  52 #define RETURN_ERROR_IF_RO_OR_LO RETURN_ERROR_IF(read_only || list_only, EROFS)
  53
  54 int do_unlink(const char *fname)
  55 {
  56         if (dry_run) return 0;
  57         RETURN_ERROR_IF_RO_OR_LO;
  58         return unlink(fname);
  59 }
  60
  61 #ifdef SUPPORT_LINKS
  62 int do_symlink(const char *lnk, const char *fname)
  63 {
  64         if (dry_run) return 0;
  65         RETURN_ERROR_IF_RO_OR_LO;
  66
  67 #if defined NO_SYMLINK_XATTRS || defined NO_SYMLINK_USER_XATTRS
  68         /* For --fake-super, we create a normal file with mode 0600
  69          * and write the lnk into it. */
  70         if (am_root < 0) {
  71                 int ok, len = strlen(lnk);
  72                 int fd = open(fname, O_WRONLY|O_CREAT|O_TRUNC, S_IWUSR|S_IRUSR);
  73                 if (fd < 0)
  74                         return -1;
  75                 ok = write(fd, lnk, len) == len;
  76                 if (close(fd) < 0)
  77                         ok = 0;
  78                 return ok ? 0 : -1;
  79         }
  80 #endif
  81
  82         return symlink(lnk, fname);
  83 }
  84
  85 #if defined NO_SYMLINK_XATTRS || defined NO_SYMLINK_USER_XATTRS
  86 ssize_t do_readlink(const char *path, char *buf, size_t bufsiz)
  87 {
  88         /* For --fake-super, we read the link from the file. */
  89         if (am_root < 0) {
  90                 int fd = do_open_nofollow(path, O_RDONLY);
  91                 if (fd >= 0) {
  92                         int len = read(fd, buf, bufsiz);
  93                         close(fd);
  94                         return len;
  95                 }
  96                 if (errno != ELOOP)
  97                         return -1;
  98                 /* A real symlink needs to be turned into a fake one on the receiving
  99                  * side, so tell the generator that the link has no length. */
 100                 if (!am_sender)
 101                         return 0;
 102                 /* Otherwise fall through and let the sender report the real length. */
 103         }
 104
 105         return readlink(path, buf, bufsiz);
 106 }
 107 #endif
 108 #endif
 109
 110 #ifdef HAVE_LINK
 111 int do_link(const char *fname1, const char *fname2)
 112 {
 113         if (dry_run) return 0;
 114         RETURN_ERROR_IF_RO_OR_LO;
 115         return link(fname1, fname2);
 116 }
 117 #endif
 118
 119 int do_lchown(const char *path, uid_t owner, gid_t group)
 120 {
 121         if (dry_run) return 0;
 122         RETURN_ERROR_IF_RO_OR_LO;
 123 #ifndef HAVE_LCHOWN
 124 #define lchown chown
 125 #endif
 126         return lchown(path, owner, group);
 127 }
 128
 129 int do_mknod(const char *pathname, mode_t mode, dev_t dev)
 130 {
 131         if (dry_run) return 0;
 132         RETURN_ERROR_IF_RO_OR_LO;
 133
 134         /* For --fake-super, we create a normal file with mode 0600. */
 135         if (am_root < 0) {
 136                 int fd = open(pathname, O_WRONLY|O_CREAT|O_TRUNC, S_IWUSR|S_IRUSR);
 137                 if (fd < 0 || close(fd) < 0)
 138                         return -1;
 139                 return 0;
 140         }
 141
 142 #if !defined MKNOD_CREATES_FIFOS && defined HAVE_MKFIFO
 143         if (S_ISFIFO(mode))
 144                 return mkfifo(pathname, mode);
 145 #endif
 146 #if !defined MKNOD_CREATES_SOCKETS && defined HAVE_SYS_UN_H
 147         if (S_ISSOCK(mode)) {
 148                 int sock;
 149                 struct sockaddr_un saddr;
 150                 unsigned int len = strlcpy(saddr.sun_path, pathname, sizeof saddr.sun_path);
 151                 if (len >= sizeof saddr.sun_path) {
 152                         errno = ENAMETOOLONG;
 153                         return -1;
 154                 }
 155 #ifdef HAVE_SOCKADDR_UN_LEN
 156                 saddr.sun_len = len + 1;
 157 #endif
 158                 saddr.sun_family = AF_UNIX;
 159
 160                 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0
 161                     || (unlink(pathname) < 0 && errno != ENOENT)
 162                     || (bind(sock, (struct sockaddr*)&saddr, sizeof saddr)) < 0)
 163                         return -1;
 164                 close(sock);
 165 #ifdef HAVE_CHMOD
 166                 return do_chmod(pathname, mode);
 167 #else
 168                 return 0;
 169 #endif
 170         }
 171 #endif
 172 #ifdef HAVE_MKNOD
 173         return mknod(pathname, mode, dev);
 174 #else
 175         return -1;
 176 #endif
 177 }
 178
 179 int do_rmdir(const char *pathname)
 180 {
 181         if (dry_run) return 0;
 182         RETURN_ERROR_IF_RO_OR_LO;
 183         return rmdir(pathname);
 184 }
 185
 186 int do_open(const char *pathname, int flags, mode_t mode)
 187 {
 188         if (flags != O_RDONLY) {
 189                 RETURN_ERROR_IF(dry_run, 0);
 190                 RETURN_ERROR_IF_RO_OR_LO;
 191         }
 192
 193         return open(pathname, flags | O_BINARY, mode);
 194 }
 195
 196 #ifdef HAVE_CHMOD
 197 int do_chmod(const char *path, mode_t mode)
 198 {
 199         int code;
 200         if (dry_run) return 0;
 201         RETURN_ERROR_IF_RO_OR_LO;
 202 #ifdef HAVE_LCHMOD
 203         code = lchmod(path, mode & CHMOD_BITS);
 204 #else
 205         if (S_ISLNK(mode)) {
 206 # if defined HAVE_SETATTRLIST
 207                 struct attrlist attrList;
 208                 uint32_t m = mode & CHMOD_BITS; /* manpage is wrong: not mode_t! */
 209
 210                 memset(&attrList, 0, sizeof attrList);
 211                 attrList.bitmapcount = ATTR_BIT_MAP_COUNT;
 212                 attrList.commonattr = ATTR_CMN_ACCESSMASK;
 213                 code = setattrlist(path, &attrList, &m, sizeof m, FSOPT_NOFOLLOW);
 214 # else
 215                 code = 1;
 216 # endif
 217         } else
 218                 code = chmod(path, mode & CHMOD_BITS); /* DISCOURAGED FUNCTION */
 219 #endif /* !HAVE_LCHMOD */
 220         if (code != 0 && (preserve_perms || preserve_executability))
 221                 return code;
 222         return 0;
 223 }
 224 #endif
 225
 226 int do_rename(const char *fname1, const char *fname2)
 227 {
 228         if (dry_run) return 0;
 229         RETURN_ERROR_IF_RO_OR_LO;
 230         return rename(fname1, fname2);
 231 }
 232
 233 #ifdef HAVE_FTRUNCATE
 234 int do_ftruncate(int fd, OFF_T size)
 235 {
 236         int ret;
 237
 238         if (dry_run) return 0;
 239         RETURN_ERROR_IF_RO_OR_LO;
 240
 241         do {
 242                 ret = ftruncate(fd, size);
 243         } while (ret < 0 && errno == EINTR);
 244
 245         return ret;
 246 }
 247 #endif
 248
 249 void trim_trailing_slashes(char *name)
 250 {
 251         int l;
 252         /* Some BSD systems cannot make a directory if the name
 253          * contains a trailing slash.
 254          * <http://www.opensource.apple.com/bugs/X/BSD%20Kernel/2734739.html> */
 255
 256         /* Don't change empty string; and also we can't improve on
 257          * "/" */
 258
 259         l = strlen(name);
 260         while (l > 1) {
 261                 if (name[--l] != '/')
 262                         break;
 263                 name[l] = '\0';
 264         }
 265 }
 266
 267 int do_mkdir(char *fname, mode_t mode)
 268 {
 269         if (dry_run) return 0;
 270         RETURN_ERROR_IF_RO_OR_LO;
 271         trim_trailing_slashes(fname);
 272         return mkdir(fname, mode);
 273 }
 274
 275 /* like mkstemp but forces permissions */
 276 int do_mkstemp(char *template, mode_t perms)
 277 {
 278         RETURN_ERROR_IF(dry_run, 0);
 279         RETURN_ERROR_IF(read_only, EROFS);
 280         perms |= S_IWUSR;
 281
 282 #if defined HAVE_SECURE_MKSTEMP && defined HAVE_FCHMOD && (!defined HAVE_OPEN64 || defined HAVE_MKSTEMP64)
 283         {
 284                 int fd = mkstemp(template);
 285                 if (fd == -1)
 286                         return -1;
 287                 if (fchmod(fd, perms) != 0 && preserve_perms) {
 288                         int errno_save = errno;
 289                         close(fd);
 290                         unlink(template);
 291                         errno = errno_save;
 292                         return -1;
 293                 }
 294 #if defined HAVE_SETMODE && O_BINARY
 295                 setmode(fd, O_BINARY);
 296 #endif
 297                 return fd;
 298         }
 299 #else
 300         if (!mktemp(template))
 301                 return -1;
 302         return do_open(template, O_RDWR|O_EXCL|O_CREAT, perms);
 303 #endif
 304 }
 305
 306 int do_stat(const char *fname, STRUCT_STAT *st)
 307 {
 308 #ifdef USE_STAT64_FUNCS
 309         return stat64(fname, st);
 310 #else
 311         return stat(fname, st);
 312 #endif
 313 }
 314
 315 int do_lstat(const char *fname, STRUCT_STAT *st)
 316 {
 317 #ifdef SUPPORT_LINKS
 318 # ifdef USE_STAT64_FUNCS
 319         return lstat64(fname, st);
 320 # else
 321         return lstat(fname, st);
 322 # endif
 323 #else
 324         return do_stat(fname, st);
 325 #endif
 326 }
 327
 328 int do_fstat(int fd, STRUCT_STAT *st)
 329 {
 330 #ifdef USE_STAT64_FUNCS
 331         return fstat64(fd, st);
 332 #else
 333         return fstat(fd, st);
 334 #endif
 335 }
 336
 337 OFF_T do_lseek(int fd, OFF_T offset, int whence)
 338 {
 339 #ifdef HAVE_LSEEK64
 340 #if !SIZEOF_OFF64_T
 341         OFF_T lseek64();
 342 #else
 343         off64_t lseek64();
 344 #endif
 345         return lseek64(fd, offset, whence);
 346 #else
 347         return lseek(fd, offset, whence);
 348 #endif
 349 }
 350
 351 #ifdef HAVE_UTIMENSAT
 352 int do_utimensat(const char *fname, time_t modtime, uint32 mod_nsec)
 353 {
 354         struct timespec t[2];
 355
 356         if (dry_run) return 0;
 357         RETURN_ERROR_IF_RO_OR_LO;
 358
 359         t[0].tv_sec = 0;
 360         t[0].tv_nsec = UTIME_NOW;
 361         t[1].tv_sec = modtime;
 362         t[1].tv_nsec = mod_nsec;
 363         return utimensat(AT_FDCWD, fname, t, AT_SYMLINK_NOFOLLOW);
 364 }
 365 #endif
 366
 367 #ifdef HAVE_LUTIMES
 368 int do_lutimes(const char *fname, time_t modtime, uint32 mod_nsec)
 369 {
 370         struct timeval t[2];
 371
 372         if (dry_run) return 0;
 373         RETURN_ERROR_IF_RO_OR_LO;
 374
 375         t[0].tv_sec = time(NULL);
 376         t[0].tv_usec = 0;
 377         t[1].tv_sec = modtime;
 378         t[1].tv_usec = mod_nsec / 1000;
 379         return lutimes(fname, t);
 380 }
 381 #endif
 382
 383 #ifdef HAVE_UTIMES
 384 int do_utimes(const char *fname, time_t modtime, uint32 mod_nsec)
 385 {
 386         struct timeval t[2];
 387
 388         if (dry_run) return 0;
 389         RETURN_ERROR_IF_RO_OR_LO;
 390
 391         t[0].tv_sec = time(NULL);
 392         t[0].tv_usec = 0;
 393         t[1].tv_sec = modtime;
 394         t[1].tv_usec = mod_nsec / 1000;
 395         return utimes(fname, t);
 396 }
 397
 398 #elif defined HAVE_UTIME
 399 int do_utime(const char *fname, time_t modtime, UNUSED(uint32 mod_nsec))
 400 {
 401 #ifdef HAVE_STRUCT_UTIMBUF
 402         struct utimbuf tbuf;
 403 #else
 404         time_t t[2];
 405 #endif
 406
 407         if (dry_run) return 0;
 408         RETURN_ERROR_IF_RO_OR_LO;
 409
 410 # ifdef HAVE_STRUCT_UTIMBUF
 411         tbuf.actime = time(NULL);
 412         tbuf.modtime = modtime;
 413         return utime(fname, &tbuf);
 414 # else
 415         t[0] = time(NULL);
 416         t[1] = modtime;
 417         return utime(fname, t);
 418 # endif
 419 }
 420
 421 #else
 422 #error Need utimes or utime function.
 423 #endif
 424
 425 #ifdef SUPPORT_PREALLOCATION
 426 int do_fallocate(int fd, OFF_T offset, OFF_T length)
 427 {
 428 #ifdef FALLOC_FL_KEEP_SIZE
 429 #define DO_FALLOC_OPTIONS FALLOC_FL_KEEP_SIZE
 430 #else
 431 #define DO_FALLOC_OPTIONS 0
 432 #endif
 433         RETURN_ERROR_IF(dry_run, 0);
 434         RETURN_ERROR_IF_RO_OR_LO;
 435 #if defined HAVE_FALLOCATE
 436         return fallocate(fd, DO_FALLOC_OPTIONS, offset, length);
 437 #elif defined HAVE_SYS_FALLOCATE
 438         return syscall(SYS_fallocate, fd, DO_FALLOC_OPTIONS, (loff_t)offset, (loff_t)length);
 439 #elif defined HAVE_EFFICIENT_POSIX_FALLOCATE
 440         return posix_fallocate(fd, offset, length);
 441 #else
 442 #error Coding error in SUPPORT_PREALLOCATION logic.
 443 #endif
 444 }
 445 #endif
 446
 447 int do_open_nofollow(const char *pathname, int flags)
 448 {
 449 #ifndef O_NOFOLLOW
 450         STRUCT_STAT f_st, l_st;
 451 #endif
 452         int fd;
 453
 454         if (flags != O_RDONLY) {
 455                 RETURN_ERROR_IF(dry_run, 0);
 456                 RETURN_ERROR_IF_RO_OR_LO;
 457 #ifndef O_NOFOLLOW
 458                 /* This function doesn't support write attempts w/o O_NOFOLLOW. */
 459                 errno = EINVAL;
 460                 return -1;
 461 #endif
 462         }
 463
 464 #ifdef O_NOFOLLOW
 465         fd = open(pathname, flags|O_NOFOLLOW);
 466 #else
 467         if (do_lstat(pathname, &l_st) < 0)
 468                 return -1;
 469         if (S_ISLNK(l_st.st_mode)) {
 470                 errno = ELOOP;
 471                 return -1;
 472         }
 473         if ((fd = open(pathname, flags)) < 0)
 474                 return fd;
 475         if (do_fstat(fd, &f_st) < 0) {
 476           close_and_return_error:
 477                 {
 478                         int save_errno = errno;
 479                         close(fd);
 480                         errno = save_errno;
 481                 }
 482                 return -1;
 483         }
 484         if (l_st.st_dev != f_st.st_dev || l_st.st_ino != f_st.st_ino) {
 485                 errno = EINVAL;
 486                 goto close_and_return_error;
 487         }
 488 #endif
 489
 490         return fd;
 491 }