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