src/basic/fileio.c

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