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