src/basic/fileio.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <ctype.h>
   4 #include <errno.h>
   5 #include <fcntl.h>
   6 #include <limits.h>
   7 #include <stdarg.h>
   8 #include <stdint.h>
   9 #include <stdio_ext.h>
  10 #include <stdlib.h>
  11 #include <sys/stat.h>
  12 #include <sys/types.h>
  13 #include <unistd.h>
  14
  15 #include "alloc-util.h"
  16 #include "chase-symlinks.h"
  17 #include "fd-util.h"
  18 #include "fileio.h"
  19 #include "fs-util.h"
  20 #include "hexdecoct.h"
  21 #include "log.h"
  22 #include "macro.h"
  23 #include "mkdir.h"
  24 #include "parse-util.h"
  25 #include "path-util.h"
  26 #include "socket-util.h"
  27 #include "stdio-util.h"
  28 #include "string-util.h"
  29 #include "sync-util.h"
  30 #include "tmpfile-util.h"
  31
  32 /* The maximum size of the file we'll read in one go in read_full_file() (64M). */
  33 #define READ_FULL_BYTES_MAX (64U*1024U*1024U - 1U)
  34
  35 /* The maximum size of virtual files (i.e. procfs, sysfs, and other virtual "API" files) we'll read in one go
  36  * in read_virtual_file(). Note that this limit is different (and much lower) than the READ_FULL_BYTES_MAX
  37  * limit. This reflects the fact that we use different strategies for reading virtual and regular files:
  38  * virtual files we generally have to read in a single read() syscall since the kernel doesn't support
  39  * continuation read()s for them. Thankfully they are somewhat size constrained. Thus we can allocate the
  40  * full potential buffer in advance. Regular files OTOH can be much larger, and there we grow the allocations
  41  * exponentially in a loop. We use a size limit of 4M-2 because 4M-1 is the maximum buffer that /proc/sys/
  42  * allows us to read() (larger reads will fail with ENOMEM), and we want to read one extra byte so that we
  43  * can detect EOFs. */
  44 #define READ_VIRTUAL_BYTES_MAX (4U*1024U*1024U - 2U)
  45
  46 int fopen_unlocked(const char *path, const char *options, FILE **ret) {
  47         assert(ret);
  48
  49         FILE *f = fopen(path, options);
  50         if (!f)
  51                 return -errno;
  52
  53         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
  54
  55         *ret = f;
  56         return 0;
  57 }
  58
  59 int fdopen_unlocked(int fd, const char *options, FILE **ret) {
  60         assert(ret);
  61
  62         FILE *f = fdopen(fd, options);
  63         if (!f)
  64                 return -errno;
  65
  66         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
  67
  68         *ret = f;
  69         return 0;
  70 }
  71
  72 int take_fdopen_unlocked(int *fd, const char *options, FILE **ret) {
  73         int r;
  74
  75         assert(fd);
  76
  77         r = fdopen_unlocked(*fd, options, ret);
  78         if (r < 0)
  79                 return r;
  80
  81         *fd = -1;
  82
  83         return 0;
  84 }
  85
  86 FILE* take_fdopen(int *fd, const char *options) {
  87         assert(fd);
  88
  89         FILE *f = fdopen(*fd, options);
  90         if (!f)
  91                 return NULL;
  92
  93         *fd = -1;
  94
  95         return f;
  96 }
  97
  98 DIR* take_fdopendir(int *dfd) {
  99         assert(dfd);
 100
 101         DIR *d = fdopendir(*dfd);
 102         if (!d)
 103                 return NULL;
 104
 105         *dfd = -1;
 106
 107         return d;
 108 }
 109
 110 FILE* open_memstream_unlocked(char **ptr, size_t *sizeloc) {
 111         FILE *f = open_memstream(ptr, sizeloc);
 112         if (!f)
 113                 return NULL;
 114
 115         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
 116
 117         return f;
 118 }
 119
 120 FILE* fmemopen_unlocked(void *buf, size_t size, const char *mode) {
 121         FILE *f = fmemopen(buf, size, mode);
 122         if (!f)
 123                 return NULL;
 124
 125         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
 126
 127         return f;
 128 }
 129
 130 int write_string_stream_ts(
 131                 FILE *f,
 132                 const char *line,
 133                 WriteStringFileFlags flags,
 134                 const struct timespec *ts) {
 135
 136         bool needs_nl;
 137         int r, fd = -1;
 138
 139         assert(f);
 140         assert(line);
 141
 142         if (ferror(f))
 143                 return -EIO;
 144
 145         if (ts) {
 146                 /* If we shall set the timestamp we need the fd. But fmemopen() streams generally don't have
 147                  * an fd. Let's fail early in that case. */
 148                 fd = fileno(f);
 149                 if (fd < 0)
 150                         return -EBADF;
 151         }
 152
 153         if (flags & WRITE_STRING_FILE_SUPPRESS_REDUNDANT_VIRTUAL) {
 154                 _cleanup_free_ char *t = NULL;
 155
 156                 /* If value to be written is same as that of the existing value, then suppress the write. */
 157
 158                 if (fd < 0) {
 159                         fd = fileno(f);
 160                         if (fd < 0)
 161                                 return -EBADF;
 162                 }
 163
 164                 /* Read an additional byte to detect cases where the prefix matches but the rest
 165                  * doesn't. Also, 0 returned by read_virtual_file_fd() means the read was truncated and
 166                  * it won't be equal to the new value. */
 167                 if (read_virtual_file_fd(fd, strlen(line)+1, &t, NULL) > 0 &&
 168                     streq_skip_trailing_chars(line, t, NEWLINE)) {
 169                         log_debug("No change in value '%s', supressing write", line);
 170                         return 0;
 171                 }
 172
 173                 if (lseek(fd, 0, SEEK_SET) < 0)
 174                         return -errno;
 175         }
 176
 177         needs_nl = !(flags & WRITE_STRING_FILE_AVOID_NEWLINE) && !endswith(line, "\n");
 178
 179         if (needs_nl && (flags & WRITE_STRING_FILE_DISABLE_BUFFER)) {
 180                 /* If STDIO buffering was disabled, then let's append the newline character to the string
 181                  * itself, so that the write goes out in one go, instead of two */
 182
 183                 line = strjoina(line, "\n");
 184                 needs_nl = false;
 185         }
 186
 187         if (fputs(line, f) == EOF)
 188                 return -errno;
 189
 190         if (needs_nl)
 191                 if (fputc('\n', f) == EOF)
 192                         return -errno;
 193
 194         if (flags & WRITE_STRING_FILE_SYNC)
 195                 r = fflush_sync_and_check(f);
 196         else
 197                 r = fflush_and_check(f);
 198         if (r < 0)
 199                 return r;
 200
 201         if (ts) {
 202                 const struct timespec twice[2] = {*ts, *ts};
 203
 204                 assert(fd >= 0);
 205                 if (futimens(fd, twice) < 0)
 206                         return -errno;
 207         }
 208
 209         return 0;
 210 }
 211
 212 static int write_string_file_atomic(
 213                 const char *fn,
 214                 const char *line,
 215                 WriteStringFileFlags flags,
 216                 const struct timespec *ts) {
 217
 218         _cleanup_fclose_ FILE *f = NULL;
 219         _cleanup_free_ char *p = NULL;
 220         int r;
 221
 222         assert(fn);
 223         assert(line);
 224
 225         /* Note that we'd really like to use O_TMPFILE here, but can't really, since we want replacement
 226          * semantics here, and O_TMPFILE can't offer that. i.e. rename() replaces but linkat() doesn't. */
 227
 228         r = fopen_temporary(fn, &f, &p);
 229         if (r < 0)
 230                 return r;
 231
 232         r = write_string_stream_ts(f, line, flags, ts);
 233         if (r < 0)
 234                 goto fail;
 235
 236         r = fchmod_umask(fileno(f), FLAGS_SET(flags, WRITE_STRING_FILE_MODE_0600) ? 0600 : 0644);
 237         if (r < 0)
 238                 goto fail;
 239
 240         if (rename(p, fn) < 0) {
 241                 r = -errno;
 242                 goto fail;
 243         }
 244
 245         if (FLAGS_SET(flags, WRITE_STRING_FILE_SYNC)) {
 246                 /* Sync the rename, too */
 247                 r = fsync_directory_of_file(fileno(f));
 248                 if (r < 0)
 249                         return r;
 250         }
 251
 252         return 0;
 253
 254 fail:
 255         (void) unlink(p);
 256         return r;
 257 }
 258
 259 int write_string_file_ts(
 260                 const char *fn,
 261                 const char *line,
 262                 WriteStringFileFlags flags,
 263                 const struct timespec *ts) {
 264
 265         _cleanup_fclose_ FILE *f = NULL;
 266         int q, r, fd;
 267
 268         assert(fn);
 269         assert(line);
 270
 271         /* We don't know how to verify whether the file contents was already on-disk. */
 272         assert(!((flags & WRITE_STRING_FILE_VERIFY_ON_FAILURE) && (flags & WRITE_STRING_FILE_SYNC)));
 273
 274         if (flags & WRITE_STRING_FILE_MKDIR_0755) {
 275                 r = mkdir_parents(fn, 0755);
 276                 if (r < 0)
 277                         return r;
 278         }
 279
 280         if (flags & WRITE_STRING_FILE_ATOMIC) {
 281                 assert(flags & WRITE_STRING_FILE_CREATE);
 282
 283                 r = write_string_file_atomic(fn, line, flags, ts);
 284                 if (r < 0)
 285                         goto fail;
 286
 287                 return r;
 288         } else
 289                 assert(!ts);
 290
 291         /* We manually build our own version of fopen(..., "we") that works without O_CREAT and with O_NOFOLLOW if needed. */
 292         fd = open(fn, O_CLOEXEC|O_NOCTTY |
 293                   (FLAGS_SET(flags, WRITE_STRING_FILE_NOFOLLOW) ? O_NOFOLLOW : 0) |
 294                   (FLAGS_SET(flags, WRITE_STRING_FILE_CREATE) ? O_CREAT : 0) |
 295                   (FLAGS_SET(flags, WRITE_STRING_FILE_TRUNCATE) ? O_TRUNC : 0) |
 296                   (FLAGS_SET(flags, WRITE_STRING_FILE_SUPPRESS_REDUNDANT_VIRTUAL) ? O_RDWR : O_WRONLY),
 297                   (FLAGS_SET(flags, WRITE_STRING_FILE_MODE_0600) ? 0600 : 0666));
 298         if (fd < 0) {
 299                 r = -errno;
 300                 goto fail;
 301         }
 302
 303         r = fdopen_unlocked(fd, "w", &f);
 304         if (r < 0) {
 305                 safe_close(fd);
 306                 goto fail;
 307         }
 308
 309         if (flags & WRITE_STRING_FILE_DISABLE_BUFFER)
 310                 setvbuf(f, NULL, _IONBF, 0);
 311
 312         r = write_string_stream_ts(f, line, flags, ts);
 313         if (r < 0)
 314                 goto fail;
 315
 316         return 0;
 317
 318 fail:
 319         if (!(flags & WRITE_STRING_FILE_VERIFY_ON_FAILURE))
 320                 return r;
 321
 322         f = safe_fclose(f);
 323
 324         /* OK, the operation failed, but let's see if the right
 325          * contents in place already. If so, eat up the error. */
 326
 327         q = verify_file(fn, line, !(flags & WRITE_STRING_FILE_AVOID_NEWLINE) || (flags & WRITE_STRING_FILE_VERIFY_IGNORE_NEWLINE));
 328         if (q <= 0)
 329                 return r;
 330
 331         return 0;
 332 }
 333
 334 int write_string_filef(
 335                 const char *fn,
 336                 WriteStringFileFlags flags,
 337                 const char *format, ...) {
 338
 339         _cleanup_free_ char *p = NULL;
 340         va_list ap;
 341         int r;
 342
 343         va_start(ap, format);
 344         r = vasprintf(&p, format, ap);
 345         va_end(ap);
 346
 347         if (r < 0)
 348                 return -ENOMEM;
 349
 350         return write_string_file(fn, p, flags);
 351 }
 352
 353 int read_one_line_file(const char *fn, char **line) {
 354         _cleanup_fclose_ FILE *f = NULL;
 355         int r;
 356
 357         assert(fn);
 358         assert(line);
 359
 360         r = fopen_unlocked(fn, "re", &f);
 361         if (r < 0)
 362                 return r;
 363
 364         return read_line(f, LONG_LINE_MAX, line);
 365 }
 366
 367 int verify_file(const char *fn, const char *blob, bool accept_extra_nl) {
 368         _cleanup_fclose_ FILE *f = NULL;
 369         _cleanup_free_ char *buf = NULL;
 370         size_t l, k;
 371         int r;
 372
 373         assert(fn);
 374         assert(blob);
 375
 376         l = strlen(blob);
 377
 378         if (accept_extra_nl && endswith(blob, "\n"))
 379                 accept_extra_nl = false;
 380
 381         buf = malloc(l + accept_extra_nl + 1);
 382         if (!buf)
 383                 return -ENOMEM;
 384
 385         r = fopen_unlocked(fn, "re", &f);
 386         if (r < 0)
 387                 return r;
 388
 389         /* We try to read one byte more than we need, so that we know whether we hit eof */
 390         errno = 0;
 391         k = fread(buf, 1, l + accept_extra_nl + 1, f);
 392         if (ferror(f))
 393                 return errno_or_else(EIO);
 394
 395         if (k != l && k != l + accept_extra_nl)
 396                 return 0;
 397         if (memcmp(buf, blob, l) != 0)
 398                 return 0;
 399         if (k > l && buf[l] != '\n')
 400                 return 0;
 401
 402         return 1;
 403 }
 404
 405 int read_virtual_file_fd(int fd, size_t max_size, char **ret_contents, size_t *ret_size) {
 406         _cleanup_free_ char *buf = NULL;
 407         size_t n, size;
 408         int n_retries;
 409         bool truncated = false;
 410
 411         /* Virtual filesystems such as sysfs or procfs use kernfs, and kernfs can work with two sorts of
 412          * virtual files. One sort uses "seq_file", and the results of the first read are buffered for the
 413          * second read. The other sort uses "raw" reads which always go direct to the device. In the latter
 414          * case, the content of the virtual file must be retrieved with a single read otherwise a second read
 415          * might get the new value instead of finding EOF immediately. That's the reason why the usage of
 416          * fread(3) is prohibited in this case as it always performs a second call to read(2) looking for
 417          * EOF. See issue #13585.
 418          *
 419          * max_size specifies a limit on the bytes read. If max_size is SIZE_MAX, the full file is read. If
 420          * the full file is too large to read, an error is returned. For other values of max_size, *partial
 421          * contents* may be returned. (Though the read is still done using one syscall.) Returns 0 on
 422          * partial success, 1 if untruncated contents were read. */
 423
 424         assert(fd >= 0);
 425         assert(max_size <= READ_VIRTUAL_BYTES_MAX || max_size == SIZE_MAX);
 426
 427         /* Limit the number of attempts to read the number of bytes returned by fstat(). */
 428         n_retries = 3;
 429
 430         for (;;) {
 431                 struct stat st;
 432
 433                 if (fstat(fd, &st) < 0)
 434                         return -errno;
 435
 436                 if (!S_ISREG(st.st_mode))
 437                         return -EBADF;
 438
 439                 /* Be prepared for files from /proc which generally report a file size of 0. */
 440                 assert_cc(READ_VIRTUAL_BYTES_MAX < SSIZE_MAX);
 441                 if (st.st_size > 0 && n_retries > 1) {
 442                         /* Let's use the file size if we have more than 1 attempt left. On the last attempt
 443                          * we'll ignore the file size */
 444
 445                         if (st.st_size > SSIZE_MAX) { /* Avoid overflow with 32-bit size_t and 64-bit off_t. */
 446
 447                                 if (max_size == SIZE_MAX)
 448                                         return -EFBIG;
 449
 450                                 size = max_size;
 451                         } else {
 452                                 size = MIN((size_t) st.st_size, max_size);
 453
 454                                 if (size > READ_VIRTUAL_BYTES_MAX)
 455                                         return -EFBIG;
 456                         }
 457
 458                         n_retries--;
 459                 } else if (n_retries > 1) {
 460                         /* Files in /proc are generally smaller than the page size so let's start with
 461                          * a page size buffer from malloc and only use the max buffer on the final try. */
 462                         size = MIN3(page_size() - 1, READ_VIRTUAL_BYTES_MAX, max_size);
 463                         n_retries = 1;
 464                 } else {
 465                         size = MIN(READ_VIRTUAL_BYTES_MAX, max_size);
 466                         n_retries = 0;
 467                 }
 468
 469                 buf = malloc(size + 1);
 470                 if (!buf)
 471                         return -ENOMEM;
 472
 473                 /* Use a bigger allocation if we got it anyway, but not more than the limit. */
 474                 size = MIN3(MALLOC_SIZEOF_SAFE(buf) - 1, max_size, READ_VIRTUAL_BYTES_MAX);
 475
 476                 for (;;) {
 477                         ssize_t k;
 478
 479                         /* Read one more byte so we can detect whether the content of the
 480                          * file has already changed or the guessed size for files from /proc
 481                          * wasn't large enough . */
 482                         k = read(fd, buf, size + 1);
 483                         if (k >= 0) {
 484                                 n = k;
 485                                 break;
 486                         }
 487
 488                         if (errno != EINTR)
 489                                 return -errno;
 490                 }
 491
 492                 /* Consider a short read as EOF */
 493                 if (n <= size)
 494                         break;
 495
 496                 /* If a maximum size is specified and we already read more we know the file is larger, and
 497                  * can handle this as truncation case. Note that if the size of what we read equals the
 498                  * maximum size then this doesn't mean truncation, the file might or might not end on that
 499                  * byte. We need to rerun the loop in that case, with a larger buffer size, so that we read
 500                  * at least one more byte to be able to distinguish EOF from truncation. */
 501                 if (max_size != SIZE_MAX && n > max_size) {
 502                         n = size; /* Make sure we never use more than what we sized the buffer for (so that
 503                                    * we have one free byte in it for the trailing NUL we add below).*/
 504                         truncated = true;
 505                         break;
 506                 }
 507
 508                 /* We have no further attempts left? Then the file is apparently larger than our limits. Give up. */
 509                 if (n_retries <= 0)
 510                         return -EFBIG;
 511
 512                 /* Hmm... either we read too few bytes from /proc or less likely the content of the file
 513                  * might have been changed (and is now bigger) while we were processing, let's try again
 514                  * either with the new file size. */
 515
 516                 if (lseek(fd, 0, SEEK_SET) < 0)
 517                         return -errno;
 518
 519                 buf = mfree(buf);
 520         }
 521
 522         if (ret_contents) {
 523
 524                 /* Safety check: if the caller doesn't want to know the size of what we just read it will
 525                  * rely on the trailing NUL byte. But if there's an embedded NUL byte, then we should refuse
 526                  * operation as otherwise there'd be ambiguity about what we just read. */
 527                 if (!ret_size && memchr(buf, 0, n))
 528                         return -EBADMSG;
 529
 530                 if (n < size) {
 531                         char *p;
 532
 533                         /* Return rest of the buffer to libc */
 534                         p = realloc(buf, n + 1);
 535                         if (!p)
 536                                 return -ENOMEM;
 537                         buf = p;
 538                 }
 539
 540                 buf[n] = 0;
 541                 *ret_contents = TAKE_PTR(buf);
 542         }
 543
 544         if (ret_size)
 545                 *ret_size = n;
 546
 547         return !truncated;
 548 }
 549
 550 int read_virtual_file(const char *filename, size_t max_size, char **ret_contents, size_t *ret_size) {
 551         _cleanup_close_ int fd = -1;
 552
 553         assert(filename);
 554
 555         fd = open(filename, O_RDONLY | O_NOCTTY | O_CLOEXEC);
 556         if (fd < 0)
 557                 return -errno;
 558
 559         return read_virtual_file_fd(fd, max_size, ret_contents, ret_size);
 560 }
 561
 562 int read_full_stream_full(
 563                 FILE *f,
 564                 const char *filename,
 565                 uint64_t offset,
 566                 size_t size,
 567                 ReadFullFileFlags flags,
 568                 char **ret_contents,
 569                 size_t *ret_size) {
 570
 571         _cleanup_free_ char *buf = NULL;
 572         size_t n, n_next = 0, l;
 573         int fd, r;
 574
 575         assert(f);
 576         assert(ret_contents);
 577         assert(!FLAGS_SET(flags, READ_FULL_FILE_UNBASE64 | READ_FULL_FILE_UNHEX));
 578         assert(size != SIZE_MAX || !FLAGS_SET(flags, READ_FULL_FILE_FAIL_WHEN_LARGER));
 579
 580         if (offset != UINT64_MAX && offset > LONG_MAX) /* fseek() can only deal with "long" offsets */
 581                 return -ERANGE;
 582
 583         fd = fileno(f);
 584         if (fd >= 0) { /* If the FILE* object is backed by an fd (as opposed to memory or such, see
 585                         * fmemopen()), let's optimize our buffering */
 586                 struct stat st;
 587
 588                 if (fstat(fd, &st) < 0)
 589                         return -errno;
 590
 591                 if (S_ISREG(st.st_mode)) {
 592
 593                         /* Try to start with the right file size if we shall read the file in full. Note
 594                          * that we increase the size to read here by one, so that the first read attempt
 595                          * already makes us notice the EOF. If the reported size of the file is zero, we
 596                          * avoid this logic however, since quite likely it might be a virtual file in procfs
 597                          * that all report a zero file size. */
 598
 599                         if (st.st_size > 0 &&
 600                             (size == SIZE_MAX || FLAGS_SET(flags, READ_FULL_FILE_FAIL_WHEN_LARGER))) {
 601
 602                                 uint64_t rsize =
 603                                         LESS_BY((uint64_t) st.st_size, offset == UINT64_MAX ? 0 : offset);
 604
 605                                 if (rsize < SIZE_MAX) /* overflow check */
 606                                         n_next = rsize + 1;
 607                         }
 608
 609                         if (flags & READ_FULL_FILE_WARN_WORLD_READABLE)
 610                                 (void) warn_file_is_world_accessible(filename, &st, NULL, 0);
 611                 }
 612         }
 613
 614         /* If we don't know how much to read, figure it out now. If we shall read a part of the file, then
 615          * allocate the requested size. If we shall load the full file start with LINE_MAX. Note that if
 616          * READ_FULL_FILE_FAIL_WHEN_LARGER we consider the specified size a safety limit, and thus also start
 617          * with LINE_MAX, under assumption the file is most likely much shorter. */
 618         if (n_next == 0)
 619                 n_next = size != SIZE_MAX && !FLAGS_SET(flags, READ_FULL_FILE_FAIL_WHEN_LARGER) ? size : LINE_MAX;
 620
 621         /* Never read more than we need to determine that our own limit is hit */
 622         if (n_next > READ_FULL_BYTES_MAX)
 623                 n_next = READ_FULL_BYTES_MAX + 1;
 624
 625         if (offset != UINT64_MAX && fseek(f, offset, SEEK_SET) < 0)
 626                 return -errno;
 627
 628         n = l = 0;
 629         for (;;) {
 630                 char *t;
 631                 size_t k;
 632
 633                 /* If we shall fail when reading overly large data, then read exactly one byte more than the
 634                  * specified size at max, since that'll tell us if there's anymore data beyond the limit*/
 635                 if (FLAGS_SET(flags, READ_FULL_FILE_FAIL_WHEN_LARGER) && n_next > size)
 636                         n_next = size + 1;
 637
 638                 if (flags & READ_FULL_FILE_SECURE) {
 639                         t = malloc(n_next + 1);
 640                         if (!t) {
 641                                 r = -ENOMEM;
 642                                 goto finalize;
 643                         }
 644                         memcpy_safe(t, buf, n);
 645                         explicit_bzero_safe(buf, n);
 646                         free(buf);
 647                 } else {
 648                         t = realloc(buf, n_next + 1);
 649                         if (!t)
 650                                 return -ENOMEM;
 651                 }
 652
 653                 buf = t;
 654                 /* Unless a size has been explicitly specified, try to read as much as fits into the memory
 655                  * we allocated (minus 1, to leave one byte for the safety NUL byte) */
 656                 n = size == SIZE_MAX ? MALLOC_SIZEOF_SAFE(buf) - 1 : n_next;
 657
 658                 errno = 0;
 659                 k = fread(buf + l, 1, n - l, f);
 660
 661                 assert(k <= n - l);
 662                 l += k;
 663
 664                 if (ferror(f)) {
 665                         r = errno_or_else(EIO);
 666                         goto finalize;
 667                 }
 668                 if (feof(f))
 669                         break;
 670
 671                 if (size != SIZE_MAX && !FLAGS_SET(flags, READ_FULL_FILE_FAIL_WHEN_LARGER)) { /* If we got asked to read some specific size, we already sized the buffer right, hence leave */
 672                         assert(l == size);
 673                         break;
 674                 }
 675
 676                 assert(k > 0); /* we can't have read zero bytes because that would have been EOF */
 677
 678                 if (FLAGS_SET(flags, READ_FULL_FILE_FAIL_WHEN_LARGER) && l > size) {
 679                         r = -E2BIG;
 680                         goto finalize;
 681                 }
 682
 683                 if (n >= READ_FULL_BYTES_MAX) {
 684                         r = -E2BIG;
 685                         goto finalize;
 686                 }
 687
 688                 n_next = MIN(n * 2, READ_FULL_BYTES_MAX);
 689         }
 690
 691         if (flags & (READ_FULL_FILE_UNBASE64 | READ_FULL_FILE_UNHEX)) {
 692                 _cleanup_free_ void *decoded = NULL;
 693                 size_t decoded_size;
 694
 695                 buf[l++] = 0;
 696                 if (flags & READ_FULL_FILE_UNBASE64)
 697                         r = unbase64mem_full(buf, l, flags & READ_FULL_FILE_SECURE, &decoded, &decoded_size);
 698                 else
 699                         r = unhexmem_full(buf, l, flags & READ_FULL_FILE_SECURE, &decoded, &decoded_size);
 700                 if (r < 0)
 701                         goto finalize;
 702
 703                 if (flags & READ_FULL_FILE_SECURE)
 704                         explicit_bzero_safe(buf, n);
 705                 free_and_replace(buf, decoded);
 706                 n = l = decoded_size;
 707         }
 708
 709         if (!ret_size) {
 710                 /* Safety check: if the caller doesn't want to know the size of what we just read it will rely on the
 711                  * trailing NUL byte. But if there's an embedded NUL byte, then we should refuse operation as otherwise
 712                  * there'd be ambiguity about what we just read. */
 713
 714                 if (memchr(buf, 0, l)) {
 715                         r = -EBADMSG;
 716                         goto finalize;
 717                 }
 718         }
 719
 720         buf[l] = 0;
 721         *ret_contents = TAKE_PTR(buf);
 722
 723         if (ret_size)
 724                 *ret_size = l;
 725
 726         return 0;
 727
 728 finalize:
 729         if (flags & READ_FULL_FILE_SECURE)
 730                 explicit_bzero_safe(buf, n);
 731
 732         return r;
 733 }
 734
 735 int read_full_file_full(
 736                 int dir_fd,
 737                 const char *filename,
 738                 uint64_t offset,
 739                 size_t size,
 740                 ReadFullFileFlags flags,
 741                 const char *bind_name,
 742                 char **ret_contents,
 743                 size_t *ret_size) {
 744
 745         _cleanup_fclose_ FILE *f = NULL;
 746         int r;
 747
 748         assert(filename);
 749         assert(ret_contents);
 750
 751         r = xfopenat(dir_fd, filename, "re", 0, &f);
 752         if (r < 0) {
 753                 _cleanup_close_ int dfd = -1, sk = -1;
 754                 union sockaddr_union sa;
 755
 756                 /* ENXIO is what Linux returns if we open a node that is an AF_UNIX socket */
 757                 if (r != -ENXIO)
 758                         return r;
 759
 760                 /* If this is enabled, let's try to connect to it */
 761                 if (!FLAGS_SET(flags, READ_FULL_FILE_CONNECT_SOCKET))
 762                         return -ENXIO;
 763
 764                 /* Seeking is not supported on AF_UNIX sockets */
 765                 if (offset != UINT64_MAX)
 766                         return -ESPIPE;
 767
 768                 if (dir_fd == AT_FDCWD)
 769                         r = sockaddr_un_set_path(&sa.un, filename);
 770                 else {
 771                         /* If we shall operate relative to some directory, then let's use O_PATH first to
 772                          * open the socket inode, and then connect to it via /proc/self/fd/. We have to do
 773                          * this since there's not connectat() that takes a directory fd as first arg. */
 774
 775                         dfd = openat(dir_fd, filename, O_PATH|O_CLOEXEC);
 776                         if (dfd < 0)
 777                                 return -errno;
 778
 779                         r = sockaddr_un_set_path(&sa.un, FORMAT_PROC_FD_PATH(dfd));
 780                 }
 781                 if (r < 0)
 782                         return r;
 783
 784                 sk = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
 785                 if (sk < 0)
 786                         return -errno;
 787
 788                 if (bind_name) {
 789                         /* If the caller specified a socket name to bind to, do so before connecting. This is
 790                          * useful to communicate some minor, short meta-information token from the client to
 791                          * the server. */
 792                         union sockaddr_union bsa;
 793
 794                         r = sockaddr_un_set_path(&bsa.un, bind_name);
 795                         if (r < 0)
 796                                 return r;
 797
 798                         if (bind(sk, &bsa.sa, r) < 0)
 799                                 return r;
 800                 }
 801
 802                 if (connect(sk, &sa.sa, SOCKADDR_UN_LEN(sa.un)) < 0)
 803                         return errno == ENOTSOCK ? -ENXIO : -errno; /* propagate original error if this is
 804                                                                      * not a socket after all */
 805
 806                 if (shutdown(sk, SHUT_WR) < 0)
 807                         return -errno;
 808
 809                 f = fdopen(sk, "r");
 810                 if (!f)
 811                         return -errno;
 812
 813                 TAKE_FD(sk);
 814         }
 815
 816         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
 817
 818         return read_full_stream_full(f, filename, offset, size, flags, ret_contents, ret_size);
 819 }
 820
 821 int executable_is_script(const char *path, char **interpreter) {
 822         _cleanup_free_ char *line = NULL;
 823         size_t len;
 824         char *ans;
 825         int r;
 826
 827         assert(path);
 828
 829         r = read_one_line_file(path, &line);
 830         if (r == -ENOBUFS) /* First line overly long? if so, then it's not a script */
 831                 return 0;
 832         if (r < 0)
 833                 return r;
 834
 835         if (!startswith(line, "#!"))
 836                 return 0;
 837
 838         ans = strstrip(line + 2);
 839         len = strcspn(ans, " \t");
 840
 841         if (len == 0)
 842                 return 0;
 843
 844         ans = strndup(ans, len);
 845         if (!ans)
 846                 return -ENOMEM;
 847
 848         *interpreter = ans;
 849         return 1;
 850 }
 851
 852 /**
 853  * Retrieve one field from a file like /proc/self/status.  pattern
 854  * should not include whitespace or the delimiter (':'). pattern matches only
 855  * the beginning of a line. Whitespace before ':' is skipped. Whitespace and
 856  * zeros after the ':' will be skipped. field must be freed afterwards.
 857  * terminator specifies the terminating characters of the field value (not
 858  * included in the value).
 859  */
 860 int get_proc_field(const char *filename, const char *pattern, const char *terminator, char **field) {
 861         _cleanup_free_ char *status = NULL;
 862         char *t, *f;
 863         size_t len;
 864         int r;
 865
 866         assert(terminator);
 867         assert(filename);
 868         assert(pattern);
 869         assert(field);
 870
 871         r = read_full_virtual_file(filename, &status, NULL);
 872         if (r < 0)
 873                 return r;
 874
 875         t = status;
 876
 877         do {
 878                 bool pattern_ok;
 879
 880                 do {
 881                         t = strstr(t, pattern);
 882                         if (!t)
 883                                 return -ENOENT;
 884
 885                         /* Check that pattern occurs in beginning of line. */
 886                         pattern_ok = (t == status || t[-1] == '\n');
 887
 888                         t += strlen(pattern);
 889
 890                 } while (!pattern_ok);
 891
 892                 t += strspn(t, " \t");
 893                 if (!*t)
 894                         return -ENOENT;
 895
 896         } while (*t != ':');
 897
 898         t++;
 899
 900         if (*t) {
 901                 t += strspn(t, " \t");
 902
 903                 /* Also skip zeros, because when this is used for
 904                  * capabilities, we don't want the zeros. This way the
 905                  * same capability set always maps to the same string,
 906                  * irrespective of the total capability set size. For
 907                  * other numbers it shouldn't matter. */
 908                 t += strspn(t, "0");
 909                 /* Back off one char if there's nothing but whitespace
 910                    and zeros */
 911                 if (!*t || isspace(*t))
 912                         t--;
 913         }
 914
 915         len = strcspn(t, terminator);
 916
 917         f = strndup(t, len);
 918         if (!f)
 919                 return -ENOMEM;
 920
 921         *field = f;
 922         return 0;
 923 }
 924
 925 DIR *xopendirat(int fd, const char *name, int flags) {
 926         int nfd;
 927         DIR *d;
 928
 929         assert(!(flags & O_CREAT));
 930
 931         nfd = openat(fd, name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|flags, 0);
 932         if (nfd < 0)
 933                 return NULL;
 934
 935         d = fdopendir(nfd);
 936         if (!d) {
 937                 safe_close(nfd);
 938                 return NULL;
 939         }
 940
 941         return d;
 942 }
 943
 944 static int mode_to_flags(const char *mode) {
 945         const char *p;
 946         int flags;
 947
 948         if ((p = startswith(mode, "r+")))
 949                 flags = O_RDWR;
 950         else if ((p = startswith(mode, "r")))
 951                 flags = O_RDONLY;
 952         else if ((p = startswith(mode, "w+")))
 953                 flags = O_RDWR|O_CREAT|O_TRUNC;
 954         else if ((p = startswith(mode, "w")))
 955                 flags = O_WRONLY|O_CREAT|O_TRUNC;
 956         else if ((p = startswith(mode, "a+")))
 957                 flags = O_RDWR|O_CREAT|O_APPEND;
 958         else if ((p = startswith(mode, "a")))
 959                 flags = O_WRONLY|O_CREAT|O_APPEND;
 960         else
 961                 return -EINVAL;
 962
 963         for (; *p != 0; p++) {
 964
 965                 switch (*p) {
 966
 967                 case 'e':
 968                         flags |= O_CLOEXEC;
 969                         break;
 970
 971                 case 'x':
 972                         flags |= O_EXCL;
 973                         break;
 974
 975                 case 'm':
 976                         /* ignore this here, fdopen() might care later though */
 977                         break;
 978
 979                 case 'c': /* not sure what to do about this one */
 980                 default:
 981                         return -EINVAL;
 982                 }
 983         }
 984
 985         return flags;
 986 }
 987
 988 int xfopenat(int dir_fd, const char *path, const char *mode, int flags, FILE **ret) {
 989         FILE *f;
 990
 991         /* A combination of fopen() with openat() */
 992
 993         if (dir_fd == AT_FDCWD && flags == 0) {
 994                 f = fopen(path, mode);
 995                 if (!f)
 996                         return -errno;
 997         } else {
 998                 int fd, mode_flags;
 999
1000                 mode_flags = mode_to_flags(mode);
1001                 if (mode_flags < 0)
1002                         return mode_flags;
1003
1004                 fd = openat(dir_fd, path, mode_flags | flags);
1005                 if (fd < 0)
1006                         return -errno;
1007
1008                 f = fdopen(fd, mode);
1009                 if (!f) {
1010                         safe_close(fd);
1011                         return -errno;
1012                 }
1013         }
1014
1015         *ret = f;
1016         return 0;
1017 }
1018
1019 static int search_and_fopen_internal(
1020                 const char *path,
1021                 const char *mode,
1022                 const char *root,
1023                 char **search,
1024                 FILE **ret,
1025                 char **ret_path) {
1026
1027         char **i;
1028
1029         assert(path);
1030         assert(mode);
1031         assert(ret);
1032
1033         if (!path_strv_resolve_uniq(search, root))
1034                 return -ENOMEM;
1035
1036         STRV_FOREACH(i, search) {
1037                 _cleanup_free_ char *p = NULL;
1038                 FILE *f;
1039
1040                 p = path_join(root, *i, path);
1041                 if (!p)
1042                         return -ENOMEM;
1043
1044                 f = fopen(p, mode);
1045                 if (f) {
1046                         if (ret_path)
1047                                 *ret_path = path_simplify(TAKE_PTR(p));
1048
1049                         *ret = f;
1050                         return 0;
1051                 }
1052
1053                 if (errno != ENOENT)
1054                         return -errno;
1055         }
1056
1057         return -ENOENT;
1058 }
1059
1060 int search_and_fopen(
1061                 const char *filename,
1062                 const char *mode,
1063                 const char *root,
1064                 const char **search,
1065                 FILE **ret,
1066                 char **ret_path) {
1067
1068         _cleanup_strv_free_ char **copy = NULL;
1069
1070         assert(filename);
1071         assert(mode);
1072         assert(ret);
1073
1074         if (path_is_absolute(filename)) {
1075                 _cleanup_fclose_ FILE *f = NULL;
1076
1077                 f = fopen(filename, mode);
1078                 if (!f)
1079                         return -errno;
1080
1081                 if (ret_path) {
1082                         char *p;
1083
1084                         p = strdup(filename);
1085                         if (!p)
1086                                 return -ENOMEM;
1087
1088                         *ret_path = path_simplify(p);
1089                 }
1090
1091                 *ret = TAKE_PTR(f);
1092                 return 0;
1093         }
1094
1095         copy = strv_copy((char**) search);
1096         if (!copy)
1097                 return -ENOMEM;
1098
1099         return search_and_fopen_internal(filename, mode, root, copy, ret, ret_path);
1100 }
1101
1102 int search_and_fopen_nulstr(
1103                 const char *filename,
1104                 const char *mode,
1105                 const char *root,
1106                 const char *search,
1107                 FILE **ret,
1108                 char **ret_path) {
1109
1110         _cleanup_strv_free_ char **s = NULL;
1111
1112         if (path_is_absolute(filename)) {
1113                 _cleanup_fclose_ FILE *f = NULL;
1114
1115                 f = fopen(filename, mode);
1116                 if (!f)
1117                         return -errno;
1118
1119                 if (ret_path) {
1120                         char *p;
1121
1122                         p = strdup(filename);
1123                         if (!p)
1124                                 return -ENOMEM;
1125
1126                         *ret_path = path_simplify(p);
1127                 }
1128
1129                 *ret = TAKE_PTR(f);
1130                 return 0;
1131         }
1132
1133         s = strv_split_nulstr(search);
1134         if (!s)
1135                 return -ENOMEM;
1136
1137         return search_and_fopen_internal(filename, mode, root, s, ret, ret_path);
1138 }
1139
1140 int chase_symlinks_and_fopen_unlocked(
1141                 const char *path,
1142                 const char *root,
1143                 unsigned chase_flags,
1144                 const char *open_flags,
1145                 FILE **ret_file,
1146                 char **ret_path) {
1147
1148         _cleanup_close_ int fd = -1;
1149         _cleanup_free_ char *final_path = NULL;
1150         int mode_flags, r;
1151
1152         assert(path);
1153         assert(open_flags);
1154         assert(ret_file);
1155
1156         mode_flags = mode_to_flags(open_flags);
1157         if (mode_flags < 0)
1158                 return mode_flags;
1159
1160         fd = chase_symlinks_and_open(path, root, chase_flags, mode_flags, ret_path ? &final_path : NULL);
1161         if (fd < 0)
1162                 return fd;
1163
1164         r = take_fdopen_unlocked(&fd, open_flags, ret_file);
1165         if (r < 0)
1166                 return r;
1167
1168         if (ret_path)
1169                 *ret_path = TAKE_PTR(final_path);
1170         return 0;
1171 }
1172
1173 int fflush_and_check(FILE *f) {
1174         assert(f);
1175
1176         errno = 0;
1177         fflush(f);
1178
1179         if (ferror(f))
1180                 return errno_or_else(EIO);
1181
1182         return 0;
1183 }
1184
1185 int fflush_sync_and_check(FILE *f) {
1186         int r, fd;
1187
1188         assert(f);
1189
1190         r = fflush_and_check(f);
1191         if (r < 0)
1192                 return r;
1193
1194         /* Not all file streams have an fd associated (think: fmemopen()), let's handle this gracefully and
1195          * assume that in that case we need no explicit syncing */
1196         fd = fileno(f);
1197         if (fd < 0)
1198                 return 0;
1199
1200         r = fsync_full(fd);
1201         if (r < 0)
1202                 return r;
1203
1204         return 0;
1205 }
1206
1207 int write_timestamp_file_atomic(const char *fn, usec_t n) {
1208         char ln[DECIMAL_STR_MAX(n)+2];
1209
1210         /* Creates a "timestamp" file, that contains nothing but a
1211          * usec_t timestamp, formatted in ASCII. */
1212
1213         if (n <= 0 || n >= USEC_INFINITY)
1214                 return -ERANGE;
1215
1216         xsprintf(ln, USEC_FMT "\n", n);
1217
1218         return write_string_file(fn, ln, WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_ATOMIC);
1219 }
1220
1221 int read_timestamp_file(const char *fn, usec_t *ret) {
1222         _cleanup_free_ char *ln = NULL;
1223         uint64_t t;
1224         int r;
1225
1226         r = read_one_line_file(fn, &ln);
1227         if (r < 0)
1228                 return r;
1229
1230         r = safe_atou64(ln, &t);
1231         if (r < 0)
1232                 return r;
1233
1234         if (t <= 0 || t >= (uint64_t) USEC_INFINITY)
1235                 return -ERANGE;
1236
1237         *ret = (usec_t) t;
1238         return 0;
1239 }
1240
1241 int fputs_with_space(FILE *f, const char *s, const char *separator, bool *space) {
1242         int r;
1243
1244         assert(s);
1245
1246         /* Outputs the specified string with fputs(), but optionally prefixes it with a separator. The *space parameter
1247          * when specified shall initially point to a boolean variable initialized to false. It is set to true after the
1248          * first invocation. This call is supposed to be use in loops, where a separator shall be inserted between each
1249          * element, but not before the first one. */
1250
1251         if (!f)
1252                 f = stdout;
1253
1254         if (space) {
1255                 if (!separator)
1256                         separator = " ";
1257
1258                 if (*space) {
1259                         r = fputs(separator, f);
1260                         if (r < 0)
1261                                 return r;
1262                 }
1263
1264                 *space = true;
1265         }
1266
1267         return fputs(s, f);
1268 }
1269
1270 /* A bitmask of the EOL markers we know */
1271 typedef enum EndOfLineMarker {
1272         EOL_NONE     = 0,
1273         EOL_ZERO     = 1 << 0,  /* \0 (aka NUL) */
1274         EOL_TEN      = 1 << 1,  /* \n (aka NL, aka LF)  */
1275         EOL_THIRTEEN = 1 << 2,  /* \r (aka CR)  */
1276 } EndOfLineMarker;
1277
1278 static EndOfLineMarker categorize_eol(char c, ReadLineFlags flags) {
1279
1280         if (!IN_SET(flags, READ_LINE_ONLY_NUL)) {
1281                 if (c == '\n')
1282                         return EOL_TEN;
1283                 if (c == '\r')
1284                         return EOL_THIRTEEN;
1285         }
1286
1287         if (c == '\0')
1288                 return EOL_ZERO;
1289
1290         return EOL_NONE;
1291 }
1292
1293 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(FILE*, funlockfile, NULL);
1294
1295 int read_line_full(FILE *f, size_t limit, ReadLineFlags flags, char **ret) {
1296         _cleanup_free_ char *buffer = NULL;
1297         size_t n = 0, count = 0;
1298         int r;
1299
1300         assert(f);
1301
1302         /* Something like a bounded version of getline().
1303          *
1304          * Considers EOF, \n, \r and \0 end of line delimiters (or combinations of these), and does not include these
1305          * delimiters in the string returned. Specifically, recognizes the following combinations of markers as line
1306          * endings:
1307          *
1308          *     • \n        (UNIX)
1309          *     • \r        (old MacOS)
1310          *     • \0        (C strings)
1311          *     • \n\0
1312          *     • \r\0
1313          *     • \r\n      (Windows)
1314          *     • \n\r
1315          *     • \r\n\0
1316          *     • \n\r\0
1317          *
1318          * Returns the number of bytes read from the files (i.e. including delimiters — this hence usually differs from
1319          * the number of characters in the returned string). When EOF is hit, 0 is returned.
1320          *
1321          * The input parameter limit is the maximum numbers of characters in the returned string, i.e. excluding
1322          * delimiters. If the limit is hit we fail and return -ENOBUFS.
1323          *
1324          * If a line shall be skipped ret may be initialized as NULL. */
1325
1326         if (ret) {
1327                 if (!GREEDY_REALLOC(buffer, 1))
1328                         return -ENOMEM;
1329         }
1330
1331         {
1332                 _unused_ _cleanup_(funlockfilep) FILE *flocked = f;
1333                 EndOfLineMarker previous_eol = EOL_NONE;
1334                 flockfile(f);
1335
1336                 for (;;) {
1337                         EndOfLineMarker eol;
1338                         char c;
1339
1340                         if (n >= limit)
1341                                 return -ENOBUFS;
1342
1343                         if (count >= INT_MAX) /* We couldn't return the counter anymore as "int", hence refuse this */
1344                                 return -ENOBUFS;
1345
1346                         r = safe_fgetc(f, &c);
1347                         if (r < 0)
1348                                 return r;
1349                         if (r == 0) /* EOF is definitely EOL */
1350                                 break;
1351
1352                         eol = categorize_eol(c, flags);
1353
1354                         if (FLAGS_SET(previous_eol, EOL_ZERO) ||
1355                             (eol == EOL_NONE && previous_eol != EOL_NONE) ||
1356                             (eol != EOL_NONE && (previous_eol & eol) != 0)) {
1357                                 /* Previous char was a NUL? This is not an EOL, but the previous char was? This type of
1358                                  * EOL marker has been seen right before?  In either of these three cases we are
1359                                  * done. But first, let's put this character back in the queue. (Note that we have to
1360                                  * cast this to (unsigned char) here as ungetc() expects a positive 'int', and if we
1361                                  * are on an architecture where 'char' equals 'signed char' we need to ensure we don't
1362                                  * pass a negative value here. That said, to complicate things further ungetc() is
1363                                  * actually happy with most negative characters and implicitly casts them back to
1364                                  * positive ones as needed, except for \xff (aka -1, aka EOF), which it refuses. What a
1365                                  * godawful API!) */
1366                                 assert_se(ungetc((unsigned char) c, f) != EOF);
1367                                 break;
1368                         }
1369
1370                         count++;
1371
1372                         if (eol != EOL_NONE) {
1373                                 /* If we are on a tty, we can't shouldn't wait for more input, because that
1374                                  * generally means waiting for the user, interactively. In the case of a TTY
1375                                  * we expect only \n as the single EOL marker, so we are in the lucky
1376                                  * position that there is no need to wait. We check this condition last, to
1377                                  * avoid isatty() check if not necessary. */
1378
1379                                 if ((flags & (READ_LINE_IS_A_TTY|READ_LINE_NOT_A_TTY)) == 0) {
1380                                         int fd;
1381
1382                                         fd = fileno(f);
1383                                         if (fd < 0) /* Maybe an fmemopen() stream? Handle this gracefully,
1384                                                      * and don't call isatty() on an invalid fd */
1385                                                 flags |= READ_LINE_NOT_A_TTY;
1386                                         else
1387                                                 flags |= isatty(fd) ? READ_LINE_IS_A_TTY : READ_LINE_NOT_A_TTY;
1388                                 }
1389                                 if (FLAGS_SET(flags, READ_LINE_IS_A_TTY))
1390                                         break;
1391                         }
1392
1393                         if (eol != EOL_NONE) {
1394                                 previous_eol |= eol;
1395                                 continue;
1396                         }
1397
1398                         if (ret) {
1399                                 if (!GREEDY_REALLOC(buffer, n + 2))
1400                                         return -ENOMEM;
1401
1402                                 buffer[n] = c;
1403                         }
1404
1405                         n++;
1406                 }
1407         }
1408
1409         if (ret) {
1410                 buffer[n] = 0;
1411
1412                 *ret = TAKE_PTR(buffer);
1413         }
1414
1415         return (int) count;
1416 }
1417
1418 int safe_fgetc(FILE *f, char *ret) {
1419         int k;
1420
1421         assert(f);
1422
1423         /* A safer version of plain fgetc(): let's propagate the error that happened while reading as such, and
1424          * separate the EOF condition from the byte read, to avoid those confusion signed/unsigned issues fgetc()
1425          * has. */
1426
1427         errno = 0;
1428         k = fgetc(f);
1429         if (k == EOF) {
1430                 if (ferror(f))
1431                         return errno_or_else(EIO);
1432
1433                 if (ret)
1434                         *ret = 0;
1435
1436                 return 0;
1437         }
1438
1439         if (ret)
1440                 *ret = k;
1441
1442         return 1;
1443 }
1444
1445 int warn_file_is_world_accessible(const char *filename, struct stat *st, const char *unit, unsigned line) {
1446         struct stat _st;
1447
1448         if (!filename)
1449                 return 0;
1450
1451         if (!st) {
1452                 if (stat(filename, &_st) < 0)
1453                         return -errno;
1454                 st = &_st;
1455         }
1456
1457         if ((st->st_mode & S_IRWXO) == 0)
1458                 return 0;
1459
1460         if (unit)
1461                 log_syntax(unit, LOG_WARNING, filename, line, 0,
1462                            "%s has %04o mode that is too permissive, please adjust the ownership and access mode.",
1463                            filename, st->st_mode & 07777);
1464         else
1465                 log_warning("%s has %04o mode that is too permissive, please adjust the ownership and access mode.",
1466                             filename, st->st_mode & 07777);
1467         return 0;
1468 }