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_MODE_0600) ? 0600 : 0666));
 257         if (fd < 0) {
 258                 r = -errno;
 259                 goto fail;
 260         }
 261
 262         r = fdopen_unlocked(fd, "w", &f);
 263         if (r < 0) {
 264                 safe_close(fd);
 265                 goto fail;
 266         }
 267
 268         if (flags & WRITE_STRING_FILE_DISABLE_BUFFER)
 269                 setvbuf(f, NULL, _IONBF, 0);
 270
 271         r = write_string_stream_ts(f, line, flags, ts);
 272         if (r < 0)
 273                 goto fail;
 274
 275         return 0;
 276
 277 fail:
 278         if (!(flags & WRITE_STRING_FILE_VERIFY_ON_FAILURE))
 279                 return r;
 280
 281         f = safe_fclose(f);
 282
 283         /* OK, the operation failed, but let's see if the right
 284          * contents in place already. If so, eat up the error. */
 285
 286         q = verify_file(fn, line, !(flags & WRITE_STRING_FILE_AVOID_NEWLINE));
 287         if (q <= 0)
 288                 return r;
 289
 290         return 0;
 291 }
 292
 293 int write_string_filef(
 294                 const char *fn,
 295                 WriteStringFileFlags flags,
 296                 const char *format, ...) {
 297
 298         _cleanup_free_ char *p = NULL;
 299         va_list ap;
 300         int r;
 301
 302         va_start(ap, format);
 303         r = vasprintf(&p, format, ap);
 304         va_end(ap);
 305
 306         if (r < 0)
 307                 return -ENOMEM;
 308
 309         return write_string_file(fn, p, flags);
 310 }
 311
 312 int read_one_line_file(const char *fn, char **line) {
 313         _cleanup_fclose_ FILE *f = NULL;
 314         int r;
 315
 316         assert(fn);
 317         assert(line);
 318
 319         r = fopen_unlocked(fn, "re", &f);
 320         if (r < 0)
 321                 return r;
 322
 323         return read_line(f, LONG_LINE_MAX, line);
 324 }
 325
 326 int verify_file(const char *fn, const char *blob, bool accept_extra_nl) {
 327         _cleanup_fclose_ FILE *f = NULL;
 328         _cleanup_free_ char *buf = NULL;
 329         size_t l, k;
 330         int r;
 331
 332         assert(fn);
 333         assert(blob);
 334
 335         l = strlen(blob);
 336
 337         if (accept_extra_nl && endswith(blob, "\n"))
 338                 accept_extra_nl = false;
 339
 340         buf = malloc(l + accept_extra_nl + 1);
 341         if (!buf)
 342                 return -ENOMEM;
 343
 344         r = fopen_unlocked(fn, "re", &f);
 345         if (r < 0)
 346                 return r;
 347
 348         /* We try to read one byte more than we need, so that we know whether we hit eof */
 349         errno = 0;
 350         k = fread(buf, 1, l + accept_extra_nl + 1, f);
 351         if (ferror(f))
 352                 return errno_or_else(EIO);
 353
 354         if (k != l && k != l + accept_extra_nl)
 355                 return 0;
 356         if (memcmp(buf, blob, l) != 0)
 357                 return 0;
 358         if (k > l && buf[l] != '\n')
 359                 return 0;
 360
 361         return 1;
 362 }
 363
 364 int read_full_virtual_file(const char *filename, char **ret_contents, size_t *ret_size) {
 365         _cleanup_free_ char *buf = NULL;
 366         _cleanup_close_ int fd = -1;
 367         struct stat st;
 368         size_t n, size;
 369         int n_retries;
 370         char *p;
 371
 372         assert(ret_contents);
 373
 374         /* Virtual filesystems such as sysfs or procfs use kernfs, and kernfs can work
 375          * with two sorts of virtual files. One sort uses "seq_file", and the results of
 376          * the first read are buffered for the second read. The other sort uses "raw"
 377          * reads which always go direct to the device. In the latter case, the content of
 378          * the virtual file must be retrieved with a single read otherwise a second read
 379          * might get the new value instead of finding EOF immediately. That's the reason
 380          * why the usage of fread(3) is prohibited in this case as it always performs a
 381          * second call to read(2) looking for EOF. See issue 13585. */
 382
 383         fd = open(filename, O_RDONLY|O_CLOEXEC);
 384         if (fd < 0)
 385                 return -errno;
 386
 387         /* Start size for files in /proc which usually report a file size of 0. */
 388         size = LINE_MAX / 2;
 389
 390         /* Limit the number of attempts to read the number of bytes returned by fstat(). */
 391         n_retries = 3;
 392
 393         for (;;) {
 394                 if (n_retries <= 0)
 395                         return -EIO;
 396
 397                 if (fstat(fd, &st) < 0)
 398                         return -errno;
 399
 400                 if (!S_ISREG(st.st_mode))
 401                         return -EBADF;
 402
 403                 /* Be prepared for files from /proc which generally report a file size of 0. */
 404                 if (st.st_size > 0) {
 405                         size = st.st_size;
 406                         n_retries--;
 407                 } else
 408                         size = size * 2;
 409
 410                 if (size > READ_FULL_BYTES_MAX)
 411                         return -E2BIG;
 412
 413                 p = realloc(buf, size + 1);
 414                 if (!p)
 415                         return -ENOMEM;
 416                 buf = TAKE_PTR(p);
 417
 418                 for (;;) {
 419                         ssize_t k;
 420
 421                         /* Read one more byte so we can detect whether the content of the
 422                          * file has already changed or the guessed size for files from /proc
 423                          * wasn't large enough . */
 424                         k = read(fd, buf, size + 1);
 425                         if (k >= 0) {
 426                                 n = k;
 427                                 break;
 428                         }
 429
 430                         if (errno != EINTR)
 431                                 return -errno;
 432                 }
 433
 434                 /* Consider a short read as EOF */
 435                 if (n <= size)
 436                         break;
 437
 438                 /* Hmm... either we read too few bytes from /proc or less likely the content
 439                  * of the file might have been changed (and is now bigger) while we were
 440                  * processing, let's try again either with a bigger guessed size or the new
 441                  * file size. */
 442
 443                 if (lseek(fd, 0, SEEK_SET) < 0)
 444                         return -errno;
 445         }
 446
 447         if (n < size) {
 448                 p = realloc(buf, n + 1);
 449                 if (!p)
 450                         return -ENOMEM;
 451                 buf = TAKE_PTR(p);
 452         }
 453
 454         if (!ret_size) {
 455                 /* Safety check: if the caller doesn't want to know the size of what we
 456                  * just read it will rely on the trailing NUL byte. But if there's an
 457                  * embedded NUL byte, then we should refuse operation as otherwise
 458                  * there'd be ambiguity about what we just read. */
 459
 460                 if (memchr(buf, 0, n))
 461                         return -EBADMSG;
 462         } else
 463                 *ret_size = n;
 464
 465         buf[n] = 0;
 466         *ret_contents = TAKE_PTR(buf);
 467
 468         return 0;
 469 }
 470
 471 int read_full_stream_full(
 472                 FILE *f,
 473                 const char *filename,
 474                 ReadFullFileFlags flags,
 475                 char **ret_contents,
 476                 size_t *ret_size) {
 477
 478         _cleanup_free_ char *buf = NULL;
 479         struct stat st;
 480         size_t n, n_next, l;
 481         int fd, r;
 482
 483         assert(f);
 484         assert(ret_contents);
 485         assert(!FLAGS_SET(flags, READ_FULL_FILE_UNBASE64 | READ_FULL_FILE_UNHEX));
 486
 487         n_next = LINE_MAX; /* Start size */
 488
 489         fd = fileno(f);
 490         if (fd >= 0) { /* If the FILE* object is backed by an fd (as opposed to memory or such, see fmemopen()), let's
 491                         * optimize our buffering */
 492
 493                 if (fstat(fd, &st) < 0)
 494                         return -errno;
 495
 496                 if (S_ISREG(st.st_mode)) {
 497
 498                         /* Safety check */
 499                         if (st.st_size > READ_FULL_BYTES_MAX)
 500                                 return -E2BIG;
 501
 502                         /* Start with the right file size. Note that we increase the size
 503                          * to read here by one, so that the first read attempt already
 504                          * makes us notice the EOF. */
 505                         if (st.st_size > 0)
 506                                 n_next = st.st_size + 1;
 507
 508                         if (flags & READ_FULL_FILE_WARN_WORLD_READABLE)
 509                                 (void) warn_file_is_world_accessible(filename, &st, NULL, 0);
 510                 }
 511         }
 512
 513         n = l = 0;
 514         for (;;) {
 515                 char *t;
 516                 size_t k;
 517
 518                 if (flags & READ_FULL_FILE_SECURE) {
 519                         t = malloc(n_next + 1);
 520                         if (!t) {
 521                                 r = -ENOMEM;
 522                                 goto finalize;
 523                         }
 524                         memcpy_safe(t, buf, n);
 525                         explicit_bzero_safe(buf, n);
 526                         buf = mfree(buf);
 527                 } else {
 528                         t = realloc(buf, n_next + 1);
 529                         if (!t)
 530                                 return -ENOMEM;
 531                 }
 532
 533                 buf = t;
 534                 n = n_next;
 535
 536                 errno = 0;
 537                 k = fread(buf + l, 1, n - l, f);
 538
 539                 assert(k <= n - l);
 540                 l += k;
 541
 542                 if (ferror(f)) {
 543                         r = errno_or_else(EIO);
 544                         goto finalize;
 545                 }
 546                 if (feof(f))
 547                         break;
 548
 549                 assert(k > 0); /* we can't have read zero bytes because that would have been EOF */
 550
 551                 /* Safety check */
 552                 if (n >= READ_FULL_BYTES_MAX) {
 553                         r = -E2BIG;
 554                         goto finalize;
 555                 }
 556
 557                 n_next = MIN(n * 2, READ_FULL_BYTES_MAX);
 558         }
 559
 560         if (flags & (READ_FULL_FILE_UNBASE64 | READ_FULL_FILE_UNHEX)) {
 561                 _cleanup_free_ void *decoded = NULL;
 562                 size_t decoded_size;
 563
 564                 buf[l++] = 0;
 565                 if (flags & READ_FULL_FILE_UNBASE64)
 566                         r = unbase64mem_full(buf, l, flags & READ_FULL_FILE_SECURE, &decoded, &decoded_size);
 567                 else
 568                         r = unhexmem_full(buf, l, flags & READ_FULL_FILE_SECURE, &decoded, &decoded_size);
 569                 if (r < 0)
 570                         goto finalize;
 571
 572                 if (flags & READ_FULL_FILE_SECURE)
 573                         explicit_bzero_safe(buf, n);
 574                 free_and_replace(buf, decoded);
 575                 n = l = decoded_size;
 576         }
 577
 578         if (!ret_size) {
 579                 /* Safety check: if the caller doesn't want to know the size of what we just read it will rely on the
 580                  * trailing NUL byte. But if there's an embedded NUL byte, then we should refuse operation as otherwise
 581                  * there'd be ambiguity about what we just read. */
 582
 583                 if (memchr(buf, 0, l)) {
 584                         r = -EBADMSG;
 585                         goto finalize;
 586                 }
 587         }
 588
 589         buf[l] = 0;
 590         *ret_contents = TAKE_PTR(buf);
 591
 592         if (ret_size)
 593                 *ret_size = l;
 594
 595         return 0;
 596
 597 finalize:
 598         if (flags & READ_FULL_FILE_SECURE)
 599                 explicit_bzero_safe(buf, n);
 600
 601         return r;
 602 }
 603
 604 int read_full_file_full(int dir_fd, const char *filename, ReadFullFileFlags flags, char **contents, size_t *size) {
 605         _cleanup_fclose_ FILE *f = NULL;
 606         int r;
 607
 608         assert(filename);
 609         assert(contents);
 610
 611         r = xfopenat(dir_fd, filename, "re", 0, &f);
 612         if (r < 0) {
 613                 _cleanup_close_ int dfd = -1, sk = -1;
 614                 union sockaddr_union sa;
 615
 616                 /* ENXIO is what Linux returns if we open a node that is an AF_UNIX socket */
 617                 if (r != -ENXIO)
 618                         return r;
 619
 620                 /* If this is enabled, let's try to connect to it */
 621                 if (!FLAGS_SET(flags, READ_FULL_FILE_CONNECT_SOCKET))
 622                         return -ENXIO;
 623
 624                 if (dir_fd == AT_FDCWD)
 625                         r = sockaddr_un_set_path(&sa.un, filename);
 626                 else {
 627                         char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)];
 628
 629                         /* If we shall operate relative to some directory, then let's use O_PATH first to
 630                          * open the socket inode, and then connect to it via /proc/self/fd/. We have to do
 631                          * this since there's not connectat() that takes a directory fd as first arg. */
 632
 633                         dfd = openat(dir_fd, filename, O_PATH|O_CLOEXEC);
 634                         if (dfd < 0)
 635                                 return -errno;
 636
 637                         xsprintf(procfs_path, "/proc/self/fd/%i", dfd);
 638                         r = sockaddr_un_set_path(&sa.un, procfs_path);
 639                 }
 640                 if (r < 0)
 641                         return r;
 642
 643                 sk = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
 644                 if (sk < 0)
 645                         return -errno;
 646
 647                 if (connect(sk, &sa.sa, SOCKADDR_UN_LEN(sa.un)) < 0)
 648                         return errno == ENOTSOCK ? -ENXIO : -errno; /* propagate original error if this is
 649                                                                      * not a socket after all */
 650
 651                 if (shutdown(sk, SHUT_WR) < 0)
 652                         return -errno;
 653
 654                 f = fdopen(sk, "r");
 655                 if (!f)
 656                         return -errno;
 657
 658                 TAKE_FD(sk);
 659         }
 660
 661         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
 662
 663         return read_full_stream_full(f, filename, flags, contents, size);
 664 }
 665
 666 int executable_is_script(const char *path, char **interpreter) {
 667         _cleanup_free_ char *line = NULL;
 668         size_t len;
 669         char *ans;
 670         int r;
 671
 672         assert(path);
 673
 674         r = read_one_line_file(path, &line);
 675         if (r == -ENOBUFS) /* First line overly long? if so, then it's not a script */
 676                 return 0;
 677         if (r < 0)
 678                 return r;
 679
 680         if (!startswith(line, "#!"))
 681                 return 0;
 682
 683         ans = strstrip(line + 2);
 684         len = strcspn(ans, " \t");
 685
 686         if (len == 0)
 687                 return 0;
 688
 689         ans = strndup(ans, len);
 690         if (!ans)
 691                 return -ENOMEM;
 692
 693         *interpreter = ans;
 694         return 1;
 695 }
 696
 697 /**
 698  * Retrieve one field from a file like /proc/self/status.  pattern
 699  * should not include whitespace or the delimiter (':'). pattern matches only
 700  * the beginning of a line. Whitespace before ':' is skipped. Whitespace and
 701  * zeros after the ':' will be skipped. field must be freed afterwards.
 702  * terminator specifies the terminating characters of the field value (not
 703  * included in the value).
 704  */
 705 int get_proc_field(const char *filename, const char *pattern, const char *terminator, char **field) {
 706         _cleanup_free_ char *status = NULL;
 707         char *t, *f;
 708         size_t len;
 709         int r;
 710
 711         assert(terminator);
 712         assert(filename);
 713         assert(pattern);
 714         assert(field);
 715
 716         r = read_full_virtual_file(filename, &status, NULL);
 717         if (r < 0)
 718                 return r;
 719
 720         t = status;
 721
 722         do {
 723                 bool pattern_ok;
 724
 725                 do {
 726                         t = strstr(t, pattern);
 727                         if (!t)
 728                                 return -ENOENT;
 729
 730                         /* Check that pattern occurs in beginning of line. */
 731                         pattern_ok = (t == status || t[-1] == '\n');
 732
 733                         t += strlen(pattern);
 734
 735                 } while (!pattern_ok);
 736
 737                 t += strspn(t, " \t");
 738                 if (!*t)
 739                         return -ENOENT;
 740
 741         } while (*t != ':');
 742
 743         t++;
 744
 745         if (*t) {
 746                 t += strspn(t, " \t");
 747
 748                 /* Also skip zeros, because when this is used for
 749                  * capabilities, we don't want the zeros. This way the
 750                  * same capability set always maps to the same string,
 751                  * irrespective of the total capability set size. For
 752                  * other numbers it shouldn't matter. */
 753                 t += strspn(t, "0");
 754                 /* Back off one char if there's nothing but whitespace
 755                    and zeros */
 756                 if (!*t || isspace(*t))
 757                         t--;
 758         }
 759
 760         len = strcspn(t, terminator);
 761
 762         f = strndup(t, len);
 763         if (!f)
 764                 return -ENOMEM;
 765
 766         *field = f;
 767         return 0;
 768 }
 769
 770 DIR *xopendirat(int fd, const char *name, int flags) {
 771         int nfd;
 772         DIR *d;
 773
 774         assert(!(flags & O_CREAT));
 775
 776         nfd = openat(fd, name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|flags, 0);
 777         if (nfd < 0)
 778                 return NULL;
 779
 780         d = fdopendir(nfd);
 781         if (!d) {
 782                 safe_close(nfd);
 783                 return NULL;
 784         }
 785
 786         return d;
 787 }
 788
 789 static int mode_to_flags(const char *mode) {
 790         const char *p;
 791         int flags;
 792
 793         if ((p = startswith(mode, "r+")))
 794                 flags = O_RDWR;
 795         else if ((p = startswith(mode, "r")))
 796                 flags = O_RDONLY;
 797         else if ((p = startswith(mode, "w+")))
 798                 flags = O_RDWR|O_CREAT|O_TRUNC;
 799         else if ((p = startswith(mode, "w")))
 800                 flags = O_WRONLY|O_CREAT|O_TRUNC;
 801         else if ((p = startswith(mode, "a+")))
 802                 flags = O_RDWR|O_CREAT|O_APPEND;
 803         else if ((p = startswith(mode, "a")))
 804                 flags = O_WRONLY|O_CREAT|O_APPEND;
 805         else
 806                 return -EINVAL;
 807
 808         for (; *p != 0; p++) {
 809
 810                 switch (*p) {
 811
 812                 case 'e':
 813                         flags |= O_CLOEXEC;
 814                         break;
 815
 816                 case 'x':
 817                         flags |= O_EXCL;
 818                         break;
 819
 820                 case 'm':
 821                         /* ignore this here, fdopen() might care later though */
 822                         break;
 823
 824                 case 'c': /* not sure what to do about this one */
 825                 default:
 826                         return -EINVAL;
 827                 }
 828         }
 829
 830         return flags;
 831 }
 832
 833 int xfopenat(int dir_fd, const char *path, const char *mode, int flags, FILE **ret) {
 834         FILE *f;
 835
 836         /* A combination of fopen() with openat() */
 837
 838         if (dir_fd == AT_FDCWD && flags == 0) {
 839                 f = fopen(path, mode);
 840                 if (!f)
 841                         return -errno;
 842         } else {
 843                 int fd, mode_flags;
 844
 845                 mode_flags = mode_to_flags(mode);
 846                 if (mode_flags < 0)
 847                         return mode_flags;
 848
 849                 fd = openat(dir_fd, path, mode_flags | flags);
 850                 if (fd < 0)
 851                         return -errno;
 852
 853                 f = fdopen(fd, mode);
 854                 if (!f) {
 855                         safe_close(fd);
 856                         return -errno;
 857                 }
 858         }
 859
 860         *ret = f;
 861         return 0;
 862 }
 863
 864 static int search_and_fopen_internal(const char *path, const char *mode, const char *root, char **search, FILE **_f) {
 865         char **i;
 866
 867         assert(path);
 868         assert(mode);
 869         assert(_f);
 870
 871         if (!path_strv_resolve_uniq(search, root))
 872                 return -ENOMEM;
 873
 874         STRV_FOREACH(i, search) {
 875                 _cleanup_free_ char *p = NULL;
 876                 FILE *f;
 877
 878                 p = path_join(root, *i, path);
 879                 if (!p)
 880                         return -ENOMEM;
 881
 882                 f = fopen(p, mode);
 883                 if (f) {
 884                         *_f = f;
 885                         return 0;
 886                 }
 887
 888                 if (errno != ENOENT)
 889                         return -errno;
 890         }
 891
 892         return -ENOENT;
 893 }
 894
 895 int search_and_fopen(const char *path, const char *mode, const char *root, const char **search, FILE **_f) {
 896         _cleanup_strv_free_ char **copy = NULL;
 897
 898         assert(path);
 899         assert(mode);
 900         assert(_f);
 901
 902         if (path_is_absolute(path)) {
 903                 FILE *f;
 904
 905                 f = fopen(path, mode);
 906                 if (f) {
 907                         *_f = f;
 908                         return 0;
 909                 }
 910
 911                 return -errno;
 912         }
 913
 914         copy = strv_copy((char**) search);
 915         if (!copy)
 916                 return -ENOMEM;
 917
 918         return search_and_fopen_internal(path, mode, root, copy, _f);
 919 }
 920
 921 int search_and_fopen_nulstr(const char *path, const char *mode, const char *root, const char *search, FILE **_f) {
 922         _cleanup_strv_free_ char **s = NULL;
 923
 924         if (path_is_absolute(path)) {
 925                 FILE *f;
 926
 927                 f = fopen(path, mode);
 928                 if (f) {
 929                         *_f = f;
 930                         return 0;
 931                 }
 932
 933                 return -errno;
 934         }
 935
 936         s = strv_split_nulstr(search);
 937         if (!s)
 938                 return -ENOMEM;
 939
 940         return search_and_fopen_internal(path, mode, root, s, _f);
 941 }
 942
 943 int chase_symlinks_and_fopen_unlocked(
 944                 const char *path,
 945                 const char *root,
 946                 unsigned chase_flags,
 947                 const char *open_flags,
 948                 FILE **ret_file,
 949                 char **ret_path) {
 950
 951         _cleanup_close_ int fd = -1;
 952         _cleanup_free_ char *final_path = NULL;
 953         int mode_flags, r;
 954         FILE *f;
 955
 956         assert(path);
 957         assert(open_flags);
 958         assert(ret_file);
 959
 960         mode_flags = mode_to_flags(open_flags);
 961         if (mode_flags < 0)
 962                 return mode_flags;
 963
 964         fd = chase_symlinks_and_open(path, root, chase_flags, mode_flags, ret_path ? &final_path : NULL);
 965         if (fd < 0)
 966                 return fd;
 967
 968         r = fdopen_unlocked(fd, open_flags, &f);
 969         if (r < 0)
 970                 return r;
 971         TAKE_FD(fd);
 972
 973         *ret_file = f;
 974         if (ret_path)
 975                 *ret_path = TAKE_PTR(final_path);
 976         return 0;
 977 }
 978
 979 int fflush_and_check(FILE *f) {
 980         assert(f);
 981
 982         errno = 0;
 983         fflush(f);
 984
 985         if (ferror(f))
 986                 return errno_or_else(EIO);
 987
 988         return 0;
 989 }
 990
 991 int fflush_sync_and_check(FILE *f) {
 992         int r, fd;
 993
 994         assert(f);
 995
 996         r = fflush_and_check(f);
 997         if (r < 0)
 998                 return r;
 999
1000         /* Not all file streams have an fd associated (think: fmemopen()), let's handle this gracefully and
1001          * assume that in that case we need no explicit syncing */
1002         fd = fileno(f);
1003         if (fd < 0)
1004                 return 0;
1005
1006         if (fsync(fd) < 0)
1007                 return -errno;
1008
1009         r = fsync_directory_of_file(fd);
1010         if (r < 0)
1011                 return r;
1012
1013         return 0;
1014 }
1015
1016 int write_timestamp_file_atomic(const char *fn, usec_t n) {
1017         char ln[DECIMAL_STR_MAX(n)+2];
1018
1019         /* Creates a "timestamp" file, that contains nothing but a
1020          * usec_t timestamp, formatted in ASCII. */
1021
1022         if (n <= 0 || n >= USEC_INFINITY)
1023                 return -ERANGE;
1024
1025         xsprintf(ln, USEC_FMT "\n", n);
1026
1027         return write_string_file(fn, ln, WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_ATOMIC);
1028 }
1029
1030 int read_timestamp_file(const char *fn, usec_t *ret) {
1031         _cleanup_free_ char *ln = NULL;
1032         uint64_t t;
1033         int r;
1034
1035         r = read_one_line_file(fn, &ln);
1036         if (r < 0)
1037                 return r;
1038
1039         r = safe_atou64(ln, &t);
1040         if (r < 0)
1041                 return r;
1042
1043         if (t <= 0 || t >= (uint64_t) USEC_INFINITY)
1044                 return -ERANGE;
1045
1046         *ret = (usec_t) t;
1047         return 0;
1048 }
1049
1050 int fputs_with_space(FILE *f, const char *s, const char *separator, bool *space) {
1051         int r;
1052
1053         assert(s);
1054
1055         /* Outputs the specified string with fputs(), but optionally prefixes it with a separator. The *space parameter
1056          * when specified shall initially point to a boolean variable initialized to false. It is set to true after the
1057          * first invocation. This call is supposed to be use in loops, where a separator shall be inserted between each
1058          * element, but not before the first one. */
1059
1060         if (!f)
1061                 f = stdout;
1062
1063         if (space) {
1064                 if (!separator)
1065                         separator = " ";
1066
1067                 if (*space) {
1068                         r = fputs(separator, f);
1069                         if (r < 0)
1070                                 return r;
1071                 }
1072
1073                 *space = true;
1074         }
1075
1076         return fputs(s, f);
1077 }
1078
1079 /* A bitmask of the EOL markers we know */
1080 typedef enum EndOfLineMarker {
1081         EOL_NONE     = 0,
1082         EOL_ZERO     = 1 << 0,  /* \0 (aka NUL) */
1083         EOL_TEN      = 1 << 1,  /* \n (aka NL, aka LF)  */
1084         EOL_THIRTEEN = 1 << 2,  /* \r (aka CR)  */
1085 } EndOfLineMarker;
1086
1087 static EndOfLineMarker categorize_eol(char c, ReadLineFlags flags) {
1088
1089         if (!IN_SET(flags, READ_LINE_ONLY_NUL)) {
1090                 if (c == '\n')
1091                         return EOL_TEN;
1092                 if (c == '\r')
1093                         return EOL_THIRTEEN;
1094         }
1095
1096         if (c == '\0')
1097                 return EOL_ZERO;
1098
1099         return EOL_NONE;
1100 }
1101
1102 DEFINE_TRIVIAL_CLEANUP_FUNC(FILE*, funlockfile);
1103
1104 int read_line_full(FILE *f, size_t limit, ReadLineFlags flags, char **ret) {
1105         size_t n = 0, allocated = 0, count = 0;
1106         _cleanup_free_ char *buffer = NULL;
1107         int r;
1108
1109         assert(f);
1110
1111         /* Something like a bounded version of getline().
1112          *
1113          * Considers EOF, \n, \r and \0 end of line delimiters (or combinations of these), and does not include these
1114          * delimiters in the string returned. Specifically, recognizes the following combinations of markers as line
1115          * endings:
1116          *
1117          *     • \n        (UNIX)
1118          *     • \r        (old MacOS)
1119          *     • \0        (C strings)
1120          *     • \n\0
1121          *     • \r\0
1122          *     • \r\n      (Windows)
1123          *     • \n\r
1124          *     • \r\n\0
1125          *     • \n\r\0
1126          *
1127          * Returns the number of bytes read from the files (i.e. including delimiters — this hence usually differs from
1128          * the number of characters in the returned string). When EOF is hit, 0 is returned.
1129          *
1130          * The input parameter limit is the maximum numbers of characters in the returned string, i.e. excluding
1131          * delimiters. If the limit is hit we fail and return -ENOBUFS.
1132          *
1133          * If a line shall be skipped ret may be initialized as NULL. */
1134
1135         if (ret) {
1136                 if (!GREEDY_REALLOC(buffer, allocated, 1))
1137                         return -ENOMEM;
1138         }
1139
1140         {
1141                 _unused_ _cleanup_(funlockfilep) FILE *flocked = f;
1142                 EndOfLineMarker previous_eol = EOL_NONE;
1143                 flockfile(f);
1144
1145                 for (;;) {
1146                         EndOfLineMarker eol;
1147                         char c;
1148
1149                         if (n >= limit)
1150                                 return -ENOBUFS;
1151
1152                         if (count >= INT_MAX) /* We couldn't return the counter anymore as "int", hence refuse this */
1153                                 return -ENOBUFS;
1154
1155                         r = safe_fgetc(f, &c);
1156                         if (r < 0)
1157                                 return r;
1158                         if (r == 0) /* EOF is definitely EOL */
1159                                 break;
1160
1161                         eol = categorize_eol(c, flags);
1162
1163                         if (FLAGS_SET(previous_eol, EOL_ZERO) ||
1164                             (eol == EOL_NONE && previous_eol != EOL_NONE) ||
1165                             (eol != EOL_NONE && (previous_eol & eol) != 0)) {
1166                                 /* Previous char was a NUL? This is not an EOL, but the previous char was? This type of
1167                                  * EOL marker has been seen right before?  In either of these three cases we are
1168                                  * done. But first, let's put this character back in the queue. (Note that we have to
1169                                  * cast this to (unsigned char) here as ungetc() expects a positive 'int', and if we
1170                                  * are on an architecture where 'char' equals 'signed char' we need to ensure we don't
1171                                  * pass a negative value here. That said, to complicate things further ungetc() is
1172                                  * actually happy with most negative characters and implicitly casts them back to
1173                                  * positive ones as needed, except for \xff (aka -1, aka EOF), which it refuses. What a
1174                                  * godawful API!) */
1175                                 assert_se(ungetc((unsigned char) c, f) != EOF);
1176                                 break;
1177                         }
1178
1179                         count++;
1180
1181                         if (eol != EOL_NONE) {
1182                                 /* If we are on a tty, we can't shouldn't wait for more input, because that
1183                                  * generally means waiting for the user, interactively. In the case of a TTY
1184                                  * we expect only \n as the single EOL marker, so we are in the lucky
1185                                  * position that there is no need to wait. We check this condition last, to
1186                                  * avoid isatty() check if not necessary. */
1187
1188                                 if ((flags & (READ_LINE_IS_A_TTY|READ_LINE_NOT_A_TTY)) == 0) {
1189                                         int fd;
1190
1191                                         fd = fileno(f);
1192                                         if (fd < 0) /* Maybe an fmemopen() stream? Handle this gracefully,
1193                                                      * and don't call isatty() on an invalid fd */
1194                                                 flags |= READ_LINE_NOT_A_TTY;
1195                                         else
1196                                                 flags |= isatty(fd) ? READ_LINE_IS_A_TTY : READ_LINE_NOT_A_TTY;
1197                                 }
1198                                 if (FLAGS_SET(flags, READ_LINE_IS_A_TTY))
1199                                         break;
1200                         }
1201
1202                         if (eol != EOL_NONE) {
1203                                 previous_eol |= eol;
1204                                 continue;
1205                         }
1206
1207                         if (ret) {
1208                                 if (!GREEDY_REALLOC(buffer, allocated, n + 2))
1209                                         return -ENOMEM;
1210
1211                                 buffer[n] = c;
1212                         }
1213
1214                         n++;
1215                 }
1216         }
1217
1218         if (ret) {
1219                 buffer[n] = 0;
1220
1221                 *ret = TAKE_PTR(buffer);
1222         }
1223
1224         return (int) count;
1225 }
1226
1227 int safe_fgetc(FILE *f, char *ret) {
1228         int k;
1229
1230         assert(f);
1231
1232         /* A safer version of plain fgetc(): let's propagate the error that happened while reading as such, and
1233          * separate the EOF condition from the byte read, to avoid those confusion signed/unsigned issues fgetc()
1234          * has. */
1235
1236         errno = 0;
1237         k = fgetc(f);
1238         if (k == EOF) {
1239                 if (ferror(f))
1240                         return errno_or_else(EIO);
1241
1242                 if (ret)
1243                         *ret = 0;
1244
1245                 return 0;
1246         }
1247
1248         if (ret)
1249                 *ret = k;
1250
1251         return 1;
1252 }
1253
1254 int warn_file_is_world_accessible(const char *filename, struct stat *st, const char *unit, unsigned line) {
1255         struct stat _st;
1256
1257         if (!filename)
1258                 return 0;
1259
1260         if (!st) {
1261                 if (stat(filename, &_st) < 0)
1262                         return -errno;
1263                 st = &_st;
1264         }
1265
1266         if ((st->st_mode & S_IRWXO) == 0)
1267                 return 0;
1268
1269         if (unit)
1270                 log_syntax(unit, LOG_WARNING, filename, line, 0,
1271                            "%s has %04o mode that is too permissive, please adjust the ownership and access mode.",
1272                            filename, st->st_mode & 07777);
1273         else
1274                 log_warning("%s has %04o mode that is too permissive, please adjust the ownership and access mode.",
1275                             filename, st->st_mode & 07777);
1276         return 0;
1277 }
1278
1279 int sync_rights(int from, int to) {
1280         struct stat st;
1281
1282         if (fstat(from, &st) < 0)
1283                 return -errno;
1284
1285         return fchmod_and_chown(to, st.st_mode & 07777, st.st_uid, st.st_gid);
1286 }
1287
1288 int rename_and_apply_smack_floor_label(const char *from, const char *to) {
1289         int r = 0;
1290         if (rename(from, to) < 0)
1291                 return -errno;
1292
1293 #ifdef SMACK_RUN_LABEL
1294         r = mac_smack_apply(to, SMACK_ATTR_ACCESS, SMACK_FLOOR_LABEL);
1295         if (r < 0)
1296                 return r;
1297 #endif
1298         return r;
1299 }