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