src/basic/fileio.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <ctype.h>
   4 #include <errno.h>
   5 #include <fcntl.h>
   6 #include <limits.h>
   7 #include <stdarg.h>
   8 #include <stdint.h>
   9 #include <stdio_ext.h>
  10 #include <stdlib.h>
  11 #include <sys/stat.h>
  12 #include <sys/types.h>
  13 #include <unistd.h>
  14
  15 #include "alloc-util.h"
  16 #include "fd-util.h"
  17 #include "fileio.h"
  18 #include "fs-util.h"
  19 #include "hexdecoct.h"
  20 #include "log.h"
  21 #include "macro.h"
  22 #include "mkdir.h"
  23 #include "parse-util.h"
  24 #include "path-util.h"
  25 #include "socket-util.h"
  26 #include "stdio-util.h"
  27 #include "string-util.h"
  28 #include "tmpfile-util.h"
  29
  30 /* The maximum size of the file we'll read in one go. */
  31 #define READ_FULL_BYTES_MAX (4U*1024U*1024U - 1)
  32
  33 int fopen_unlocked(const char *path, const char *options, FILE **ret) {
  34         assert(ret);
  35
  36         FILE *f = fopen(path, options);
  37         if (!f)
  38                 return -errno;
  39
  40         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
  41
  42         *ret = f;
  43         return 0;
  44 }
  45
  46 int fdopen_unlocked(int fd, const char *options, FILE **ret) {
  47         assert(ret);
  48
  49         FILE *f = fdopen(fd, options);
  50         if (!f)
  51                 return -errno;
  52
  53         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
  54
  55         *ret = f;
  56         return 0;
  57 }
  58
  59 int take_fdopen_unlocked(int *fd, const char *options, FILE **ret) {
  60         int r;
  61
  62         assert(fd);
  63
  64         r = fdopen_unlocked(*fd, options, ret);
  65         if (r < 0)
  66                 return r;
  67
  68         *fd = -1;
  69
  70         return 0;
  71 }
  72
  73 FILE* take_fdopen(int *fd, const char *options) {
  74         assert(fd);
  75
  76         FILE *f = fdopen(*fd, options);
  77         if (!f)
  78                 return NULL;
  79
  80         *fd = -1;
  81
  82         return f;
  83 }
  84
  85 DIR* take_fdopendir(int *dfd) {
  86         assert(dfd);
  87
  88         DIR *d = fdopendir(*dfd);
  89         if (!d)
  90                 return NULL;
  91
  92         *dfd = -1;
  93
  94         return d;
  95 }
  96
  97 FILE* open_memstream_unlocked(char **ptr, size_t *sizeloc) {
  98         FILE *f = open_memstream(ptr, sizeloc);
  99         if (!f)
 100                 return NULL;
 101
 102         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
 103
 104         return f;
 105 }
 106
 107 FILE* fmemopen_unlocked(void *buf, size_t size, const char *mode) {
 108         FILE *f = fmemopen(buf, size, mode);
 109         if (!f)
 110                 return NULL;
 111
 112         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
 113
 114         return f;
 115 }
 116
 117 int write_string_stream_ts(
 118                 FILE *f,
 119                 const char *line,
 120                 WriteStringFileFlags flags,
 121                 const struct timespec *ts) {
 122
 123         bool needs_nl;
 124         int r, fd = -1;
 125
 126         assert(f);
 127         assert(line);
 128
 129         if (ferror(f))
 130                 return -EIO;
 131
 132         if (ts) {
 133                 /* If we shall set the timestamp we need the fd. But fmemopen() streams generally don't have
 134                  * an fd. Let's fail early in that case. */
 135                 fd = fileno(f);
 136                 if (fd < 0)
 137                         return -EBADF;
 138         }
 139
 140         needs_nl = !(flags & WRITE_STRING_FILE_AVOID_NEWLINE) && !endswith(line, "\n");
 141
 142         if (needs_nl && (flags & WRITE_STRING_FILE_DISABLE_BUFFER)) {
 143                 /* If STDIO buffering was disabled, then let's append the newline character to the string
 144                  * itself, so that the write goes out in one go, instead of two */
 145
 146                 line = strjoina(line, "\n");
 147                 needs_nl = false;
 148         }
 149
 150         if (fputs(line, f) == EOF)
 151                 return -errno;
 152
 153         if (needs_nl)
 154                 if (fputc('\n', f) == EOF)
 155                         return -errno;
 156
 157         if (flags & WRITE_STRING_FILE_SYNC)
 158                 r = fflush_sync_and_check(f);
 159         else
 160                 r = fflush_and_check(f);
 161         if (r < 0)
 162                 return r;
 163
 164         if (ts) {
 165                 const struct timespec twice[2] = {*ts, *ts};
 166
 167                 assert(fd >= 0);
 168                 if (futimens(fd, twice) < 0)
 169                         return -errno;
 170         }
 171
 172         return 0;
 173 }
 174
 175 static int write_string_file_atomic(
 176                 const char *fn,
 177                 const char *line,
 178                 WriteStringFileFlags flags,
 179                 const struct timespec *ts) {
 180
 181         _cleanup_fclose_ FILE *f = NULL;
 182         _cleanup_free_ char *p = NULL;
 183         int r;
 184
 185         assert(fn);
 186         assert(line);
 187
 188         /* Note that we'd really like to use O_TMPFILE here, but can't really, since we want replacement
 189          * semantics here, and O_TMPFILE can't offer that. i.e. rename() replaces but linkat() doesn't. */
 190
 191         r = fopen_temporary(fn, &f, &p);
 192         if (r < 0)
 193                 return r;
 194
 195         r = write_string_stream_ts(f, line, flags, ts);
 196         if (r < 0)
 197                 goto fail;
 198
 199         r = fchmod_umask(fileno(f), FLAGS_SET(flags, WRITE_STRING_FILE_MODE_0600) ? 0600 : 0644);
 200         if (r < 0)
 201                 goto fail;
 202
 203         if (rename(p, fn) < 0) {
 204                 r = -errno;
 205                 goto fail;
 206         }
 207
 208         if (FLAGS_SET(flags, WRITE_STRING_FILE_SYNC)) {
 209                 /* Sync the rename, too */
 210                 r = fsync_directory_of_file(fileno(f));
 211                 if (r < 0)
 212                         return r;
 213         }
 214
 215         return 0;
 216
 217 fail:
 218         (void) unlink(p);
 219         return r;
 220 }
 221
 222 int write_string_file_ts(
 223                 const char *fn,
 224                 const char *line,
 225                 WriteStringFileFlags flags,
 226                 const struct timespec *ts) {
 227
 228         _cleanup_fclose_ FILE *f = NULL;
 229         int q, r, fd;
 230
 231         assert(fn);
 232         assert(line);
 233
 234         /* We don't know how to verify whether the file contents was already on-disk. */
 235         assert(!((flags & WRITE_STRING_FILE_VERIFY_ON_FAILURE) && (flags & WRITE_STRING_FILE_SYNC)));
 236
 237         if (flags & WRITE_STRING_FILE_MKDIR_0755) {
 238                 r = mkdir_parents(fn, 0755);
 239                 if (r < 0)
 240                         return r;
 241         }
 242
 243         if (flags & WRITE_STRING_FILE_ATOMIC) {
 244                 assert(flags & WRITE_STRING_FILE_CREATE);
 245
 246                 r = write_string_file_atomic(fn, line, flags, ts);
 247                 if (r < 0)
 248                         goto fail;
 249
 250                 return r;
 251         } else
 252                 assert(!ts);
 253
 254         /* We manually build our own version of fopen(..., "we") that works without O_CREAT and with O_NOFOLLOW if needed. */
 255         fd = open(fn, O_WRONLY|O_CLOEXEC|O_NOCTTY |
 256                   (FLAGS_SET(flags, WRITE_STRING_FILE_NOFOLLOW) ? O_NOFOLLOW : 0) |
 257                   (FLAGS_SET(flags, WRITE_STRING_FILE_CREATE) ? O_CREAT : 0) |
 258                   (FLAGS_SET(flags, WRITE_STRING_FILE_TRUNCATE) ? O_TRUNC : 0),
 259                   (FLAGS_SET(flags, WRITE_STRING_FILE_MODE_0600) ? 0600 : 0666));
 260         if (fd < 0) {
 261                 r = -errno;
 262                 goto fail;
 263         }
 264
 265         r = fdopen_unlocked(fd, "w", &f);
 266         if (r < 0) {
 267                 safe_close(fd);
 268                 goto fail;
 269         }
 270
 271         if (flags & WRITE_STRING_FILE_DISABLE_BUFFER)
 272                 setvbuf(f, NULL, _IONBF, 0);
 273
 274         r = write_string_stream_ts(f, line, flags, ts);
 275         if (r < 0)
 276                 goto fail;
 277
 278         return 0;
 279
 280 fail:
 281         if (!(flags & WRITE_STRING_FILE_VERIFY_ON_FAILURE))
 282                 return r;
 283
 284         f = safe_fclose(f);
 285
 286         /* OK, the operation failed, but let's see if the right
 287          * contents in place already. If so, eat up the error. */
 288
 289         q = verify_file(fn, line, !(flags & WRITE_STRING_FILE_AVOID_NEWLINE) || (flags & WRITE_STRING_FILE_VERIFY_IGNORE_NEWLINE));
 290         if (q <= 0)
 291                 return r;
 292
 293         return 0;
 294 }
 295
 296 int write_string_filef(
 297                 const char *fn,
 298                 WriteStringFileFlags flags,
 299                 const char *format, ...) {
 300
 301         _cleanup_free_ char *p = NULL;
 302         va_list ap;
 303         int r;
 304
 305         va_start(ap, format);
 306         r = vasprintf(&p, format, ap);
 307         va_end(ap);
 308
 309         if (r < 0)
 310                 return -ENOMEM;
 311
 312         return write_string_file(fn, p, flags);
 313 }
 314
 315 int read_one_line_file(const char *fn, char **line) {
 316         _cleanup_fclose_ FILE *f = NULL;
 317         int r;
 318
 319         assert(fn);
 320         assert(line);
 321
 322         r = fopen_unlocked(fn, "re", &f);
 323         if (r < 0)
 324                 return r;
 325
 326         return read_line(f, LONG_LINE_MAX, line);
 327 }
 328
 329 int verify_file(const char *fn, const char *blob, bool accept_extra_nl) {
 330         _cleanup_fclose_ FILE *f = NULL;
 331         _cleanup_free_ char *buf = NULL;
 332         size_t l, k;
 333         int r;
 334
 335         assert(fn);
 336         assert(blob);
 337
 338         l = strlen(blob);
 339
 340         if (accept_extra_nl && endswith(blob, "\n"))
 341                 accept_extra_nl = false;
 342
 343         buf = malloc(l + accept_extra_nl + 1);
 344         if (!buf)
 345                 return -ENOMEM;
 346
 347         r = fopen_unlocked(fn, "re", &f);
 348         if (r < 0)
 349                 return r;
 350
 351         /* We try to read one byte more than we need, so that we know whether we hit eof */
 352         errno = 0;
 353         k = fread(buf, 1, l + accept_extra_nl + 1, f);
 354         if (ferror(f))
 355                 return errno_or_else(EIO);
 356
 357         if (k != l && k != l + accept_extra_nl)
 358                 return 0;
 359         if (memcmp(buf, blob, l) != 0)
 360                 return 0;
 361         if (k > l && buf[l] != '\n')
 362                 return 0;
 363
 364         return 1;
 365 }
 366
 367 int read_virtual_file(const char *filename, size_t max_size, char **ret_contents, size_t *ret_size) {
 368         _cleanup_free_ char *buf = NULL;
 369         _cleanup_close_ int fd = -1;
 370         size_t n, size;
 371         int n_retries;
 372         bool truncated = false;
 373
 374         assert(ret_contents);
 375
 376         /* Virtual filesystems such as sysfs or procfs use kernfs, and kernfs can work with two sorts of
 377          * virtual files. One sort uses "seq_file", and the results of the first read are buffered for the
 378          * second read. The other sort uses "raw" reads which always go direct to the device. In the latter
 379          * case, the content of the virtual file must be retrieved with a single read otherwise a second read
 380          * might get the new value instead of finding EOF immediately. That's the reason why the usage of
 381          * fread(3) is prohibited in this case as it always performs a second call to read(2) looking for
 382          * EOF. See issue #13585.
 383          *
 384          * max_size specifies a limit on the bytes read. If max_size is SIZE_MAX, the full file is read. If
 385          * the the full file is too large to read, an error is returned. For other values of max_size,
 386          * *partial contents* may be returned. (Though the read is still done using one syscall.)
 387          * Returns 0 on partial success, 1 if untruncated contents were read. */
 388
 389         fd = open(filename, O_RDONLY|O_CLOEXEC);
 390         if (fd < 0)
 391                 return -errno;
 392
 393         assert(max_size <= READ_FULL_BYTES_MAX || max_size == SIZE_MAX);
 394
 395         /* Limit the number of attempts to read the number of bytes returned by fstat(). */
 396         n_retries = 3;
 397
 398         for (;;) {
 399                 struct stat st;
 400
 401                 if (fstat(fd, &st) < 0)
 402                         return -errno;
 403
 404                 if (!S_ISREG(st.st_mode))
 405                         return -EBADF;
 406
 407                 /* Be prepared for files from /proc which generally report a file size of 0. */
 408                 assert_cc(READ_FULL_BYTES_MAX < SSIZE_MAX);
 409                 if (st.st_size > 0) {
 410                         if (st.st_size > SSIZE_MAX) /* Avoid overflow with 32-bit size_t and 64-bit off_t. */
 411                                 return -EFBIG;
 412
 413                         size = MIN((size_t) st.st_size, max_size);
 414                         if (size > READ_FULL_BYTES_MAX)
 415                                 return -EFBIG;
 416
 417                         n_retries--;
 418                 } else {
 419                         size = MIN(READ_FULL_BYTES_MAX, max_size);
 420                         n_retries = 0;
 421                 }
 422
 423                 buf = malloc(size + 1);
 424                 if (!buf)
 425                         return -ENOMEM;
 426                 /* Use a bigger allocation if we got it anyway, but not more than the limit. */
 427                 size = MIN3(MALLOC_SIZEOF_SAFE(buf) - 1, max_size, READ_FULL_BYTES_MAX);
 428
 429                 for (;;) {
 430                         ssize_t k;
 431
 432                         /* Read one more byte so we can detect whether the content of the
 433                          * file has already changed or the guessed size for files from /proc
 434                          * wasn't large enough . */
 435                         k = read(fd, buf, size + 1);
 436                         if (k >= 0) {
 437                                 n = k;
 438                                 break;
 439                         }
 440
 441                         if (errno != EINTR)
 442                                 return -errno;
 443                 }
 444
 445                 /* Consider a short read as EOF */
 446                 if (n <= size)
 447                         break;
 448
 449                 /* Hmm... either we read too few bytes from /proc or less likely the content
 450                  * of the file might have been changed (and is now bigger) while we were
 451                  * processing, let's try again either with a bigger guessed size or the new
 452                  * file size. */
 453
 454                 if (n_retries <= 0) {
 455                         if (max_size == SIZE_MAX)
 456                                 return st.st_size > 0 ? -EIO : -EFBIG;
 457
 458                         /* Accept a short read, but truncate it appropropriately. */
 459                         n = MIN(n, max_size);
 460                         truncated = true;
 461                         break;
 462                 }
 463
 464                 if (lseek(fd, 0, SEEK_SET) < 0)
 465                         return -errno;
 466
 467                 buf = mfree(buf);
 468         }
 469
 470         if (n < size) {
 471                 char *p;
 472
 473                 /* Return rest of the buffer to libc */
 474                 p = realloc(buf, n + 1);
 475                 if (!p)
 476                         return -ENOMEM;
 477                 buf = p;
 478         }
 479
 480         if (ret_size)
 481                 *ret_size = n;
 482         else if (memchr(buf, 0, n))
 483                 /* Safety check: if the caller doesn't want to know the size of what we just read it will
 484                  * rely on the trailing NUL byte. But if there's an embedded NUL byte, then we should refuse
 485                  * operation as otherwise there'd be ambiguity about what we just read. */
 486                 return -EBADMSG;
 487
 488         buf[n] = 0;
 489         *ret_contents = TAKE_PTR(buf);
 490
 491         return !truncated;
 492 }
 493
 494 int read_full_stream_full(
 495                 FILE *f,
 496                 const char *filename,
 497                 uint64_t offset,
 498                 size_t size,
 499                 ReadFullFileFlags flags,
 500                 char **ret_contents,
 501                 size_t *ret_size) {
 502
 503         _cleanup_free_ char *buf = NULL;
 504         size_t n, n_next, l;
 505         int fd, r;
 506
 507         assert(f);
 508         assert(ret_contents);
 509         assert(!FLAGS_SET(flags, READ_FULL_FILE_UNBASE64 | READ_FULL_FILE_UNHEX));
 510
 511         if (offset != UINT64_MAX && offset > LONG_MAX)
 512                 return -ERANGE;
 513
 514         n_next = size != SIZE_MAX ? size : LINE_MAX; /* Start size */
 515
 516         fd = fileno(f);
 517         if (fd >= 0) { /* If the FILE* object is backed by an fd (as opposed to memory or such, see
 518                         * fmemopen()), let's optimize our buffering */
 519                 struct stat st;
 520
 521                 if (fstat(fd, &st) < 0)
 522                         return -errno;
 523
 524                 if (S_ISREG(st.st_mode)) {
 525                         if (size == SIZE_MAX) {
 526                                 uint64_t rsize =
 527                                         LESS_BY((uint64_t) st.st_size, offset == UINT64_MAX ? 0 : offset);
 528
 529                                 /* Safety check */
 530                                 if (rsize > READ_FULL_BYTES_MAX)
 531                                         return -E2BIG;
 532
 533                                 /* Start with the right file size. Note that we increase the size to read
 534                                  * here by one, so that the first read attempt already makes us notice the
 535                                  * EOF. If the reported size of the file is zero, we avoid this logic
 536                                  * however, since quite likely it might be a virtual file in procfs that all
 537                                  * report a zero file size. */
 538                                 if (st.st_size > 0)
 539                                         n_next = rsize + 1;
 540                         }
 541
 542                         if (flags & READ_FULL_FILE_WARN_WORLD_READABLE)
 543                                 (void) warn_file_is_world_accessible(filename, &st, NULL, 0);
 544                 }
 545         }
 546
 547         if (offset != UINT64_MAX && fseek(f, offset, SEEK_SET) < 0)
 548                 return -errno;
 549
 550         n = l = 0;
 551         for (;;) {
 552                 char *t;
 553                 size_t k;
 554
 555                 if (flags & READ_FULL_FILE_SECURE) {
 556                         t = malloc(n_next + 1);
 557                         if (!t) {
 558                                 r = -ENOMEM;
 559                                 goto finalize;
 560                         }
 561                         memcpy_safe(t, buf, n);
 562                         explicit_bzero_safe(buf, n);
 563                         buf = mfree(buf);
 564                 } else {
 565                         t = realloc(buf, n_next + 1);
 566                         if (!t)
 567                                 return -ENOMEM;
 568                 }
 569
 570                 buf = t;
 571                 /* Unless a size has been explicitly specified, try to read as much as fits into the memory
 572                  * we allocated (minus 1, to leave one byte for the safety NUL byte) */
 573                 n = size == SIZE_MAX ? MALLOC_SIZEOF_SAFE(buf) - 1 : n_next;
 574
 575                 errno = 0;
 576                 k = fread(buf + l, 1, n - l, f);
 577
 578                 assert(k <= n - l);
 579                 l += k;
 580
 581                 if (ferror(f)) {
 582                         r = errno_or_else(EIO);
 583                         goto finalize;
 584                 }
 585                 if (feof(f))
 586                         break;
 587
 588                 if (size != SIZE_MAX) { /* If we got asked to read some specific size, we already sized the buffer right, hence leave */
 589                         assert(l == size);
 590                         break;
 591                 }
 592
 593                 assert(k > 0); /* we can't have read zero bytes because that would have been EOF */
 594
 595                 /* Safety check */
 596                 if (n >= READ_FULL_BYTES_MAX) {
 597                         r = -E2BIG;
 598                         goto finalize;
 599                 }
 600
 601                 n_next = MIN(n * 2, READ_FULL_BYTES_MAX);
 602         }
 603
 604         if (flags & (READ_FULL_FILE_UNBASE64 | READ_FULL_FILE_UNHEX)) {
 605                 _cleanup_free_ void *decoded = NULL;
 606                 size_t decoded_size;
 607
 608                 buf[l++] = 0;
 609                 if (flags & READ_FULL_FILE_UNBASE64)
 610                         r = unbase64mem_full(buf, l, flags & READ_FULL_FILE_SECURE, &decoded, &decoded_size);
 611                 else
 612                         r = unhexmem_full(buf, l, flags & READ_FULL_FILE_SECURE, &decoded, &decoded_size);
 613                 if (r < 0)
 614                         goto finalize;
 615
 616                 if (flags & READ_FULL_FILE_SECURE)
 617                         explicit_bzero_safe(buf, n);
 618                 free_and_replace(buf, decoded);
 619                 n = l = decoded_size;
 620         }
 621
 622         if (!ret_size) {
 623                 /* Safety check: if the caller doesn't want to know the size of what we just read it will rely on the
 624                  * trailing NUL byte. But if there's an embedded NUL byte, then we should refuse operation as otherwise
 625                  * there'd be ambiguity about what we just read. */
 626
 627                 if (memchr(buf, 0, l)) {
 628                         r = -EBADMSG;
 629                         goto finalize;
 630                 }
 631         }
 632
 633         buf[l] = 0;
 634         *ret_contents = TAKE_PTR(buf);
 635
 636         if (ret_size)
 637                 *ret_size = l;
 638
 639         return 0;
 640
 641 finalize:
 642         if (flags & READ_FULL_FILE_SECURE)
 643                 explicit_bzero_safe(buf, n);
 644
 645         return r;
 646 }
 647
 648 int read_full_file_full(
 649                 int dir_fd,
 650                 const char *filename,
 651                 uint64_t offset,
 652                 size_t size,
 653                 ReadFullFileFlags flags,
 654                 const char *bind_name,
 655                 char **ret_contents,
 656                 size_t *ret_size) {
 657
 658         _cleanup_fclose_ FILE *f = NULL;
 659         int r;
 660
 661         assert(filename);
 662         assert(ret_contents);
 663
 664         r = xfopenat(dir_fd, filename, "re", 0, &f);
 665         if (r < 0) {
 666                 _cleanup_close_ int dfd = -1, sk = -1;
 667                 union sockaddr_union sa;
 668
 669                 /* ENXIO is what Linux returns if we open a node that is an AF_UNIX socket */
 670                 if (r != -ENXIO)
 671                         return r;
 672
 673                 /* If this is enabled, let's try to connect to it */
 674                 if (!FLAGS_SET(flags, READ_FULL_FILE_CONNECT_SOCKET))
 675                         return -ENXIO;
 676
 677                 /* Seeking is not supported on AF_UNIX sockets */
 678                 if (offset != UINT64_MAX)
 679                         return -ESPIPE;
 680
 681                 if (dir_fd == AT_FDCWD)
 682                         r = sockaddr_un_set_path(&sa.un, filename);
 683                 else {
 684                         char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)];
 685
 686                         /* If we shall operate relative to some directory, then let's use O_PATH first to
 687                          * open the socket inode, and then connect to it via /proc/self/fd/. We have to do
 688                          * this since there's not connectat() that takes a directory fd as first arg. */
 689
 690                         dfd = openat(dir_fd, filename, O_PATH|O_CLOEXEC);
 691                         if (dfd < 0)
 692                                 return -errno;
 693
 694                         xsprintf(procfs_path, "/proc/self/fd/%i", dfd);
 695                         r = sockaddr_un_set_path(&sa.un, procfs_path);
 696                 }
 697                 if (r < 0)
 698                         return r;
 699
 700                 sk = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
 701                 if (sk < 0)
 702                         return -errno;
 703
 704                 if (bind_name) {
 705                         /* If the caller specified a socket name to bind to, do so before connecting. This is
 706                          * useful to communicate some minor, short meta-information token from the client to
 707                          * the server. */
 708                         union sockaddr_union bsa;
 709
 710                         r = sockaddr_un_set_path(&bsa.un, bind_name);
 711                         if (r < 0)
 712                                 return r;
 713
 714                         if (bind(sk, &bsa.sa, r) < 0)
 715                                 return r;
 716                 }
 717
 718                 if (connect(sk, &sa.sa, SOCKADDR_UN_LEN(sa.un)) < 0)
 719                         return errno == ENOTSOCK ? -ENXIO : -errno; /* propagate original error if this is
 720                                                                      * not a socket after all */
 721
 722                 if (shutdown(sk, SHUT_WR) < 0)
 723                         return -errno;
 724
 725                 f = fdopen(sk, "r");
 726                 if (!f)
 727                         return -errno;
 728
 729                 TAKE_FD(sk);
 730         }
 731
 732         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
 733
 734         return read_full_stream_full(f, filename, offset, size, flags, ret_contents, ret_size);
 735 }
 736
 737 int executable_is_script(const char *path, char **interpreter) {
 738         _cleanup_free_ char *line = NULL;
 739         size_t len;
 740         char *ans;
 741         int r;
 742
 743         assert(path);
 744
 745         r = read_one_line_file(path, &line);
 746         if (r == -ENOBUFS) /* First line overly long? if so, then it's not a script */
 747                 return 0;
 748         if (r < 0)
 749                 return r;
 750
 751         if (!startswith(line, "#!"))
 752                 return 0;
 753
 754         ans = strstrip(line + 2);
 755         len = strcspn(ans, " \t");
 756
 757         if (len == 0)
 758                 return 0;
 759
 760         ans = strndup(ans, len);
 761         if (!ans)
 762                 return -ENOMEM;
 763
 764         *interpreter = ans;
 765         return 1;
 766 }
 767
 768 /**
 769  * Retrieve one field from a file like /proc/self/status.  pattern
 770  * should not include whitespace or the delimiter (':'). pattern matches only
 771  * the beginning of a line. Whitespace before ':' is skipped. Whitespace and
 772  * zeros after the ':' will be skipped. field must be freed afterwards.
 773  * terminator specifies the terminating characters of the field value (not
 774  * included in the value).
 775  */
 776 int get_proc_field(const char *filename, const char *pattern, const char *terminator, char **field) {
 777         _cleanup_free_ char *status = NULL;
 778         char *t, *f;
 779         size_t len;
 780         int r;
 781
 782         assert(terminator);
 783         assert(filename);
 784         assert(pattern);
 785         assert(field);
 786
 787         r = read_full_virtual_file(filename, &status, NULL);
 788         if (r < 0)
 789                 return r;
 790
 791         t = status;
 792
 793         do {
 794                 bool pattern_ok;
 795
 796                 do {
 797                         t = strstr(t, pattern);
 798                         if (!t)
 799                                 return -ENOENT;
 800
 801                         /* Check that pattern occurs in beginning of line. */
 802                         pattern_ok = (t == status || t[-1] == '\n');
 803
 804                         t += strlen(pattern);
 805
 806                 } while (!pattern_ok);
 807
 808                 t += strspn(t, " \t");
 809                 if (!*t)
 810                         return -ENOENT;
 811
 812         } while (*t != ':');
 813
 814         t++;
 815
 816         if (*t) {
 817                 t += strspn(t, " \t");
 818
 819                 /* Also skip zeros, because when this is used for
 820                  * capabilities, we don't want the zeros. This way the
 821                  * same capability set always maps to the same string,
 822                  * irrespective of the total capability set size. For
 823                  * other numbers it shouldn't matter. */
 824                 t += strspn(t, "0");
 825                 /* Back off one char if there's nothing but whitespace
 826                    and zeros */
 827                 if (!*t || isspace(*t))
 828                         t--;
 829         }
 830
 831         len = strcspn(t, terminator);
 832
 833         f = strndup(t, len);
 834         if (!f)
 835                 return -ENOMEM;
 836
 837         *field = f;
 838         return 0;
 839 }
 840
 841 DIR *xopendirat(int fd, const char *name, int flags) {
 842         int nfd;
 843         DIR *d;
 844
 845         assert(!(flags & O_CREAT));
 846
 847         nfd = openat(fd, name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|flags, 0);
 848         if (nfd < 0)
 849                 return NULL;
 850
 851         d = fdopendir(nfd);
 852         if (!d) {
 853                 safe_close(nfd);
 854                 return NULL;
 855         }
 856
 857         return d;
 858 }
 859
 860 static int mode_to_flags(const char *mode) {
 861         const char *p;
 862         int flags;
 863
 864         if ((p = startswith(mode, "r+")))
 865                 flags = O_RDWR;
 866         else if ((p = startswith(mode, "r")))
 867                 flags = O_RDONLY;
 868         else if ((p = startswith(mode, "w+")))
 869                 flags = O_RDWR|O_CREAT|O_TRUNC;
 870         else if ((p = startswith(mode, "w")))
 871                 flags = O_WRONLY|O_CREAT|O_TRUNC;
 872         else if ((p = startswith(mode, "a+")))
 873                 flags = O_RDWR|O_CREAT|O_APPEND;
 874         else if ((p = startswith(mode, "a")))
 875                 flags = O_WRONLY|O_CREAT|O_APPEND;
 876         else
 877                 return -EINVAL;
 878
 879         for (; *p != 0; p++) {
 880
 881                 switch (*p) {
 882
 883                 case 'e':
 884                         flags |= O_CLOEXEC;
 885                         break;
 886
 887                 case 'x':
 888                         flags |= O_EXCL;
 889                         break;
 890
 891                 case 'm':
 892                         /* ignore this here, fdopen() might care later though */
 893                         break;
 894
 895                 case 'c': /* not sure what to do about this one */
 896                 default:
 897                         return -EINVAL;
 898                 }
 899         }
 900
 901         return flags;
 902 }
 903
 904 int xfopenat(int dir_fd, const char *path, const char *mode, int flags, FILE **ret) {
 905         FILE *f;
 906
 907         /* A combination of fopen() with openat() */
 908
 909         if (dir_fd == AT_FDCWD && flags == 0) {
 910                 f = fopen(path, mode);
 911                 if (!f)
 912                         return -errno;
 913         } else {
 914                 int fd, mode_flags;
 915
 916                 mode_flags = mode_to_flags(mode);
 917                 if (mode_flags < 0)
 918                         return mode_flags;
 919
 920                 fd = openat(dir_fd, path, mode_flags | flags);
 921                 if (fd < 0)
 922                         return -errno;
 923
 924                 f = fdopen(fd, mode);
 925                 if (!f) {
 926                         safe_close(fd);
 927                         return -errno;
 928                 }
 929         }
 930
 931         *ret = f;
 932         return 0;
 933 }
 934
 935 static int search_and_fopen_internal(
 936                 const char *path,
 937                 const char *mode,
 938                 const char *root,
 939                 char **search,
 940                 FILE **ret,
 941                 char **ret_path) {
 942
 943         char **i;
 944
 945         assert(path);
 946         assert(mode);
 947         assert(ret);
 948
 949         if (!path_strv_resolve_uniq(search, root))
 950                 return -ENOMEM;
 951
 952         STRV_FOREACH(i, search) {
 953                 _cleanup_free_ char *p = NULL;
 954                 FILE *f;
 955
 956                 p = path_join(root, *i, path);
 957                 if (!p)
 958                         return -ENOMEM;
 959
 960                 f = fopen(p, mode);
 961                 if (f) {
 962                         if (ret_path)
 963                                 *ret_path = path_simplify(TAKE_PTR(p), true);
 964
 965                         *ret = f;
 966                         return 0;
 967                 }
 968
 969                 if (errno != ENOENT)
 970                         return -errno;
 971         }
 972
 973         return -ENOENT;
 974 }
 975
 976 int search_and_fopen(
 977                 const char *filename,
 978                 const char *mode,
 979                 const char *root,
 980                 const char **search,
 981                 FILE **ret,
 982                 char **ret_path) {
 983
 984         _cleanup_strv_free_ char **copy = NULL;
 985
 986         assert(filename);
 987         assert(mode);
 988         assert(ret);
 989
 990         if (path_is_absolute(filename)) {
 991                 _cleanup_fclose_ FILE *f = NULL;
 992
 993                 f = fopen(filename, mode);
 994                 if (!f)
 995                         return -errno;
 996
 997                 if (ret_path) {
 998                         char *p;
 999
1000                         p = strdup(filename);
1001                         if (!p)
1002                                 return -ENOMEM;
1003
1004                         *ret_path = path_simplify(p, true);
1005                 }
1006
1007                 *ret = TAKE_PTR(f);
1008                 return 0;
1009         }
1010
1011         copy = strv_copy((char**) search);
1012         if (!copy)
1013                 return -ENOMEM;
1014
1015         return search_and_fopen_internal(filename, mode, root, copy, ret, ret_path);
1016 }
1017
1018 int search_and_fopen_nulstr(
1019                 const char *filename,
1020                 const char *mode,
1021                 const char *root,
1022                 const char *search,
1023                 FILE **ret,
1024                 char **ret_path) {
1025
1026         _cleanup_strv_free_ char **s = NULL;
1027
1028         if (path_is_absolute(filename)) {
1029                 _cleanup_fclose_ FILE *f = NULL;
1030
1031                 f = fopen(filename, mode);
1032                 if (!f)
1033                         return -errno;
1034
1035                 if (ret_path) {
1036                         char *p;
1037
1038                         p = strdup(filename);
1039                         if (!p)
1040                                 return -ENOMEM;
1041
1042                         *ret_path = path_simplify(p, true);
1043                 }
1044
1045                 *ret = TAKE_PTR(f);
1046                 return 0;
1047         }
1048
1049         s = strv_split_nulstr(search);
1050         if (!s)
1051                 return -ENOMEM;
1052
1053         return search_and_fopen_internal(filename, mode, root, s, ret, ret_path);
1054 }
1055
1056 int chase_symlinks_and_fopen_unlocked(
1057                 const char *path,
1058                 const char *root,
1059                 unsigned chase_flags,
1060                 const char *open_flags,
1061                 FILE **ret_file,
1062                 char **ret_path) {
1063
1064         _cleanup_close_ int fd = -1;
1065         _cleanup_free_ char *final_path = NULL;
1066         int mode_flags, r;
1067
1068         assert(path);
1069         assert(open_flags);
1070         assert(ret_file);
1071
1072         mode_flags = mode_to_flags(open_flags);
1073         if (mode_flags < 0)
1074                 return mode_flags;
1075
1076         fd = chase_symlinks_and_open(path, root, chase_flags, mode_flags, ret_path ? &final_path : NULL);
1077         if (fd < 0)
1078                 return fd;
1079
1080         r = take_fdopen_unlocked(&fd, open_flags, ret_file);
1081         if (r < 0)
1082                 return r;
1083
1084         if (ret_path)
1085                 *ret_path = TAKE_PTR(final_path);
1086         return 0;
1087 }
1088
1089 int fflush_and_check(FILE *f) {
1090         assert(f);
1091
1092         errno = 0;
1093         fflush(f);
1094
1095         if (ferror(f))
1096                 return errno_or_else(EIO);
1097
1098         return 0;
1099 }
1100
1101 int fflush_sync_and_check(FILE *f) {
1102         int r, fd;
1103
1104         assert(f);
1105
1106         r = fflush_and_check(f);
1107         if (r < 0)
1108                 return r;
1109
1110         /* Not all file streams have an fd associated (think: fmemopen()), let's handle this gracefully and
1111          * assume that in that case we need no explicit syncing */
1112         fd = fileno(f);
1113         if (fd < 0)
1114                 return 0;
1115
1116         if (fsync(fd) < 0)
1117                 return -errno;
1118
1119         r = fsync_directory_of_file(fd);
1120         if (r < 0)
1121                 return r;
1122
1123         return 0;
1124 }
1125
1126 int write_timestamp_file_atomic(const char *fn, usec_t n) {
1127         char ln[DECIMAL_STR_MAX(n)+2];
1128
1129         /* Creates a "timestamp" file, that contains nothing but a
1130          * usec_t timestamp, formatted in ASCII. */
1131
1132         if (n <= 0 || n >= USEC_INFINITY)
1133                 return -ERANGE;
1134
1135         xsprintf(ln, USEC_FMT "\n", n);
1136
1137         return write_string_file(fn, ln, WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_ATOMIC);
1138 }
1139
1140 int read_timestamp_file(const char *fn, usec_t *ret) {
1141         _cleanup_free_ char *ln = NULL;
1142         uint64_t t;
1143         int r;
1144
1145         r = read_one_line_file(fn, &ln);
1146         if (r < 0)
1147                 return r;
1148
1149         r = safe_atou64(ln, &t);
1150         if (r < 0)
1151                 return r;
1152
1153         if (t <= 0 || t >= (uint64_t) USEC_INFINITY)
1154                 return -ERANGE;
1155
1156         *ret = (usec_t) t;
1157         return 0;
1158 }
1159
1160 int fputs_with_space(FILE *f, const char *s, const char *separator, bool *space) {
1161         int r;
1162
1163         assert(s);
1164
1165         /* Outputs the specified string with fputs(), but optionally prefixes it with a separator. The *space parameter
1166          * when specified shall initially point to a boolean variable initialized to false. It is set to true after the
1167          * first invocation. This call is supposed to be use in loops, where a separator shall be inserted between each
1168          * element, but not before the first one. */
1169
1170         if (!f)
1171                 f = stdout;
1172
1173         if (space) {
1174                 if (!separator)
1175                         separator = " ";
1176
1177                 if (*space) {
1178                         r = fputs(separator, f);
1179                         if (r < 0)
1180                                 return r;
1181                 }
1182
1183                 *space = true;
1184         }
1185
1186         return fputs(s, f);
1187 }
1188
1189 /* A bitmask of the EOL markers we know */
1190 typedef enum EndOfLineMarker {
1191         EOL_NONE     = 0,
1192         EOL_ZERO     = 1 << 0,  /* \0 (aka NUL) */
1193         EOL_TEN      = 1 << 1,  /* \n (aka NL, aka LF)  */
1194         EOL_THIRTEEN = 1 << 2,  /* \r (aka CR)  */
1195 } EndOfLineMarker;
1196
1197 static EndOfLineMarker categorize_eol(char c, ReadLineFlags flags) {
1198
1199         if (!IN_SET(flags, READ_LINE_ONLY_NUL)) {
1200                 if (c == '\n')
1201                         return EOL_TEN;
1202                 if (c == '\r')
1203                         return EOL_THIRTEEN;
1204         }
1205
1206         if (c == '\0')
1207                 return EOL_ZERO;
1208
1209         return EOL_NONE;
1210 }
1211
1212 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(FILE*, funlockfile, NULL);
1213
1214 int read_line_full(FILE *f, size_t limit, ReadLineFlags flags, char **ret) {
1215         _cleanup_free_ char *buffer = NULL;
1216         size_t n = 0, count = 0;
1217         int r;
1218
1219         assert(f);
1220
1221         /* Something like a bounded version of getline().
1222          *
1223          * Considers EOF, \n, \r and \0 end of line delimiters (or combinations of these), and does not include these
1224          * delimiters in the string returned. Specifically, recognizes the following combinations of markers as line
1225          * endings:
1226          *
1227          *     • \n        (UNIX)
1228          *     • \r        (old MacOS)
1229          *     • \0        (C strings)
1230          *     • \n\0
1231          *     • \r\0
1232          *     • \r\n      (Windows)
1233          *     • \n\r
1234          *     • \r\n\0
1235          *     • \n\r\0
1236          *
1237          * Returns the number of bytes read from the files (i.e. including delimiters — this hence usually differs from
1238          * the number of characters in the returned string). When EOF is hit, 0 is returned.
1239          *
1240          * The input parameter limit is the maximum numbers of characters in the returned string, i.e. excluding
1241          * delimiters. If the limit is hit we fail and return -ENOBUFS.
1242          *
1243          * If a line shall be skipped ret may be initialized as NULL. */
1244
1245         if (ret) {
1246                 if (!GREEDY_REALLOC(buffer, 1))
1247                         return -ENOMEM;
1248         }
1249
1250         {
1251                 _unused_ _cleanup_(funlockfilep) FILE *flocked = f;
1252                 EndOfLineMarker previous_eol = EOL_NONE;
1253                 flockfile(f);
1254
1255                 for (;;) {
1256                         EndOfLineMarker eol;
1257                         char c;
1258
1259                         if (n >= limit)
1260                                 return -ENOBUFS;
1261
1262                         if (count >= INT_MAX) /* We couldn't return the counter anymore as "int", hence refuse this */
1263                                 return -ENOBUFS;
1264
1265                         r = safe_fgetc(f, &c);
1266                         if (r < 0)
1267                                 return r;
1268                         if (r == 0) /* EOF is definitely EOL */
1269                                 break;
1270
1271                         eol = categorize_eol(c, flags);
1272
1273                         if (FLAGS_SET(previous_eol, EOL_ZERO) ||
1274                             (eol == EOL_NONE && previous_eol != EOL_NONE) ||
1275                             (eol != EOL_NONE && (previous_eol & eol) != 0)) {
1276                                 /* Previous char was a NUL? This is not an EOL, but the previous char was? This type of
1277                                  * EOL marker has been seen right before?  In either of these three cases we are
1278                                  * done. But first, let's put this character back in the queue. (Note that we have to
1279                                  * cast this to (unsigned char) here as ungetc() expects a positive 'int', and if we
1280                                  * are on an architecture where 'char' equals 'signed char' we need to ensure we don't
1281                                  * pass a negative value here. That said, to complicate things further ungetc() is
1282                                  * actually happy with most negative characters and implicitly casts them back to
1283                                  * positive ones as needed, except for \xff (aka -1, aka EOF), which it refuses. What a
1284                                  * godawful API!) */
1285                                 assert_se(ungetc((unsigned char) c, f) != EOF);
1286                                 break;
1287                         }
1288
1289                         count++;
1290
1291                         if (eol != EOL_NONE) {
1292                                 /* If we are on a tty, we can't shouldn't wait for more input, because that
1293                                  * generally means waiting for the user, interactively. In the case of a TTY
1294                                  * we expect only \n as the single EOL marker, so we are in the lucky
1295                                  * position that there is no need to wait. We check this condition last, to
1296                                  * avoid isatty() check if not necessary. */
1297
1298                                 if ((flags & (READ_LINE_IS_A_TTY|READ_LINE_NOT_A_TTY)) == 0) {
1299                                         int fd;
1300
1301                                         fd = fileno(f);
1302                                         if (fd < 0) /* Maybe an fmemopen() stream? Handle this gracefully,
1303                                                      * and don't call isatty() on an invalid fd */
1304                                                 flags |= READ_LINE_NOT_A_TTY;
1305                                         else
1306                                                 flags |= isatty(fd) ? READ_LINE_IS_A_TTY : READ_LINE_NOT_A_TTY;
1307                                 }
1308                                 if (FLAGS_SET(flags, READ_LINE_IS_A_TTY))
1309                                         break;
1310                         }
1311
1312                         if (eol != EOL_NONE) {
1313                                 previous_eol |= eol;
1314                                 continue;
1315                         }
1316
1317                         if (ret) {
1318                                 if (!GREEDY_REALLOC(buffer, n + 2))
1319                                         return -ENOMEM;
1320
1321                                 buffer[n] = c;
1322                         }
1323
1324                         n++;
1325                 }
1326         }
1327
1328         if (ret) {
1329                 buffer[n] = 0;
1330
1331                 *ret = TAKE_PTR(buffer);
1332         }
1333
1334         return (int) count;
1335 }
1336
1337 int safe_fgetc(FILE *f, char *ret) {
1338         int k;
1339
1340         assert(f);
1341
1342         /* A safer version of plain fgetc(): let's propagate the error that happened while reading as such, and
1343          * separate the EOF condition from the byte read, to avoid those confusion signed/unsigned issues fgetc()
1344          * has. */
1345
1346         errno = 0;
1347         k = fgetc(f);
1348         if (k == EOF) {
1349                 if (ferror(f))
1350                         return errno_or_else(EIO);
1351
1352                 if (ret)
1353                         *ret = 0;
1354
1355                 return 0;
1356         }
1357
1358         if (ret)
1359                 *ret = k;
1360
1361         return 1;
1362 }
1363
1364 int warn_file_is_world_accessible(const char *filename, struct stat *st, const char *unit, unsigned line) {
1365         struct stat _st;
1366
1367         if (!filename)
1368                 return 0;
1369
1370         if (!st) {
1371                 if (stat(filename, &_st) < 0)
1372                         return -errno;
1373                 st = &_st;
1374         }
1375
1376         if ((st->st_mode & S_IRWXO) == 0)
1377                 return 0;
1378
1379         if (unit)
1380                 log_syntax(unit, LOG_WARNING, filename, line, 0,
1381                            "%s has %04o mode that is too permissive, please adjust the ownership and access mode.",
1382                            filename, st->st_mode & 07777);
1383         else
1384                 log_warning("%s has %04o mode that is too permissive, please adjust the ownership and access mode.",
1385                             filename, st->st_mode & 07777);
1386         return 0;
1387 }
1388
1389 int rename_and_apply_smack_floor_label(const char *from, const char *to) {
1390         int r = 0;
1391         if (rename(from, to) < 0)
1392                 return -errno;
1393
1394 #if HAVE_SMACK_RUN_LABEL
1395         r = mac_smack_apply(to, SMACK_ATTR_ACCESS, SMACK_FLOOR_LABEL);
1396         if (r < 0)
1397                 return r;
1398 #endif
1399         return r;
1400 }