src/basic/fileio.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <limits.h>
  23 #include <stdarg.h>
  24 #include <stdint.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <sys/stat.h>
  28 #include <sys/types.h>
  29 #include <unistd.h>
  30
  31 #include "alloc-util.h"
  32 #include "ctype.h"
  33 #include "escape.h"
  34 #include "fd-util.h"
  35 #include "fileio.h"
  36 #include "fs-util.h"
  37 #include "hexdecoct.h"
  38 #include "log.h"
  39 #include "macro.h"
  40 #include "missing.h"
  41 #include "parse-util.h"
  42 #include "path-util.h"
  43 #include "random-util.h"
  44 #include "stdio-util.h"
  45 #include "string-util.h"
  46 #include "strv.h"
  47 #include "time-util.h"
  48 #include "umask-util.h"
  49 #include "utf8.h"
  50
  51 #define READ_FULL_BYTES_MAX (4U*1024U*1024U)
  52
  53 int write_string_stream(FILE *f, const char *line, bool enforce_newline) {
  54
  55         assert(f);
  56         assert(line);
  57
  58         fputs(line, f);
  59         if (enforce_newline && !endswith(line, "\n"))
  60                 fputc('\n', f);
  61
  62         return fflush_and_check(f);
  63 }
  64
  65 static int write_string_file_atomic(const char *fn, const char *line, bool enforce_newline) {
  66         _cleanup_fclose_ FILE *f = NULL;
  67         _cleanup_free_ char *p = NULL;
  68         int r;
  69
  70         assert(fn);
  71         assert(line);
  72
  73         r = fopen_temporary(fn, &f, &p);
  74         if (r < 0)
  75                 return r;
  76
  77         (void) fchmod_umask(fileno(f), 0644);
  78
  79         r = write_string_stream(f, line, enforce_newline);
  80         if (r >= 0) {
  81                 if (rename(p, fn) < 0)
  82                         r = -errno;
  83         }
  84
  85         if (r < 0)
  86                 (void) unlink(p);
  87
  88         return r;
  89 }
  90
  91 int write_string_file(const char *fn, const char *line, WriteStringFileFlags flags) {
  92         _cleanup_fclose_ FILE *f = NULL;
  93         int q, r;
  94
  95         assert(fn);
  96         assert(line);
  97
  98         if (flags & WRITE_STRING_FILE_ATOMIC) {
  99                 assert(flags & WRITE_STRING_FILE_CREATE);
 100
 101                 r = write_string_file_atomic(fn, line, !(flags & WRITE_STRING_FILE_AVOID_NEWLINE));
 102                 if (r < 0)
 103                         goto fail;
 104
 105                 return r;
 106         }
 107
 108         if (flags & WRITE_STRING_FILE_CREATE) {
 109                 f = fopen(fn, "we");
 110                 if (!f) {
 111                         r = -errno;
 112                         goto fail;
 113                 }
 114         } else {
 115                 int fd;
 116
 117                 /* We manually build our own version of fopen(..., "we") that
 118                  * works without O_CREAT */
 119                 fd = open(fn, O_WRONLY|O_CLOEXEC|O_NOCTTY);
 120                 if (fd < 0) {
 121                         r = -errno;
 122                         goto fail;
 123                 }
 124
 125                 f = fdopen(fd, "we");
 126                 if (!f) {
 127                         r = -errno;
 128                         safe_close(fd);
 129                         goto fail;
 130                 }
 131         }
 132
 133         r = write_string_stream(f, line, !(flags & WRITE_STRING_FILE_AVOID_NEWLINE));
 134         if (r < 0)
 135                 goto fail;
 136
 137         return 0;
 138
 139 fail:
 140         if (!(flags & WRITE_STRING_FILE_VERIFY_ON_FAILURE))
 141                 return r;
 142
 143         f = safe_fclose(f);
 144
 145         /* OK, the operation failed, but let's see if the right
 146          * contents in place already. If so, eat up the error. */
 147
 148         q = verify_file(fn, line, !(flags & WRITE_STRING_FILE_AVOID_NEWLINE));
 149         if (q <= 0)
 150                 return r;
 151
 152         return 0;
 153 }
 154
 155 int read_one_line_file(const char *fn, char **line) {
 156         _cleanup_fclose_ FILE *f = NULL;
 157         char t[LINE_MAX], *c;
 158
 159         assert(fn);
 160         assert(line);
 161
 162         f = fopen(fn, "re");
 163         if (!f)
 164                 return -errno;
 165
 166         if (!fgets(t, sizeof(t), f)) {
 167
 168                 if (ferror(f))
 169                         return errno > 0 ? -errno : -EIO;
 170
 171                 t[0] = 0;
 172         }
 173
 174         c = strdup(t);
 175         if (!c)
 176                 return -ENOMEM;
 177         truncate_nl(c);
 178
 179         *line = c;
 180         return 0;
 181 }
 182
 183 int verify_file(const char *fn, const char *blob, bool accept_extra_nl) {
 184         _cleanup_fclose_ FILE *f = NULL;
 185         _cleanup_free_ char *buf = NULL;
 186         size_t l, k;
 187
 188         assert(fn);
 189         assert(blob);
 190
 191         l = strlen(blob);
 192
 193         if (accept_extra_nl && endswith(blob, "\n"))
 194                 accept_extra_nl = false;
 195
 196         buf = malloc(l + accept_extra_nl + 1);
 197         if (!buf)
 198                 return -ENOMEM;
 199
 200         f = fopen(fn, "re");
 201         if (!f)
 202                 return -errno;
 203
 204         /* We try to read one byte more than we need, so that we know whether we hit eof */
 205         errno = 0;
 206         k = fread(buf, 1, l + accept_extra_nl + 1, f);
 207         if (ferror(f))
 208                 return errno > 0 ? -errno : -EIO;
 209
 210         if (k != l && k != l + accept_extra_nl)
 211                 return 0;
 212         if (memcmp(buf, blob, l) != 0)
 213                 return 0;
 214         if (k > l && buf[l] != '\n')
 215                 return 0;
 216
 217         return 1;
 218 }
 219
 220 int read_full_stream(FILE *f, char **contents, size_t *size) {
 221         size_t n, l;
 222         _cleanup_free_ char *buf = NULL;
 223         struct stat st;
 224
 225         assert(f);
 226         assert(contents);
 227
 228         if (fstat(fileno(f), &st) < 0)
 229                 return -errno;
 230
 231         n = LINE_MAX;
 232
 233         if (S_ISREG(st.st_mode)) {
 234
 235                 /* Safety check */
 236                 if (st.st_size > READ_FULL_BYTES_MAX)
 237                         return -E2BIG;
 238
 239                 /* Start with the right file size, but be prepared for
 240                  * files from /proc which generally report a file size
 241                  * of 0 */
 242                 if (st.st_size > 0)
 243                         n = st.st_size;
 244         }
 245
 246         l = 0;
 247         for (;;) {
 248                 char *t;
 249                 size_t k;
 250
 251                 t = realloc(buf, n + 1);
 252                 if (!t)
 253                         return -ENOMEM;
 254
 255                 buf = t;
 256                 k = fread(buf + l, 1, n - l, f);
 257                 if (k > 0)
 258                         l += k;
 259
 260                 if (ferror(f))
 261                         return -errno;
 262
 263                 if (feof(f))
 264                         break;
 265
 266                 /* We aren't expecting fread() to return a short read outside
 267                  * of (error && eof), assert buffer is full and enlarge buffer.
 268                  */
 269                 assert(l == n);
 270
 271                 /* Safety check */
 272                 if (n >= READ_FULL_BYTES_MAX)
 273                         return -E2BIG;
 274
 275                 n = MIN(n * 2, READ_FULL_BYTES_MAX);
 276         }
 277
 278         buf[l] = 0;
 279         *contents = buf;
 280         buf = NULL; /* do not free */
 281
 282         if (size)
 283                 *size = l;
 284
 285         return 0;
 286 }
 287
 288 int read_full_file(const char *fn, char **contents, size_t *size) {
 289         _cleanup_fclose_ FILE *f = NULL;
 290
 291         assert(fn);
 292         assert(contents);
 293
 294         f = fopen(fn, "re");
 295         if (!f)
 296                 return -errno;
 297
 298         return read_full_stream(f, contents, size);
 299 }
 300
 301 static int parse_env_file_internal(
 302                 FILE *f,
 303                 const char *fname,
 304                 const char *newline,
 305                 int (*push) (const char *filename, unsigned line,
 306                              const char *key, char *value, void *userdata, int *n_pushed),
 307                 void *userdata,
 308                 int *n_pushed) {
 309
 310         _cleanup_free_ char *contents = NULL, *key = NULL;
 311         size_t key_alloc = 0, n_key = 0, value_alloc = 0, n_value = 0, last_value_whitespace = (size_t) -1, last_key_whitespace = (size_t) -1;
 312         char *p, *value = NULL;
 313         int r;
 314         unsigned line = 1;
 315
 316         enum {
 317                 PRE_KEY,
 318                 KEY,
 319                 PRE_VALUE,
 320                 VALUE,
 321                 VALUE_ESCAPE,
 322                 SINGLE_QUOTE_VALUE,
 323                 SINGLE_QUOTE_VALUE_ESCAPE,
 324                 DOUBLE_QUOTE_VALUE,
 325                 DOUBLE_QUOTE_VALUE_ESCAPE,
 326                 COMMENT,
 327                 COMMENT_ESCAPE
 328         } state = PRE_KEY;
 329
 330         assert(newline);
 331
 332         if (f)
 333                 r = read_full_stream(f, &contents, NULL);
 334         else
 335                 r = read_full_file(fname, &contents, NULL);
 336         if (r < 0)
 337                 return r;
 338
 339         for (p = contents; *p; p++) {
 340                 char c = *p;
 341
 342                 switch (state) {
 343
 344                 case PRE_KEY:
 345                         if (strchr(COMMENTS, c))
 346                                 state = COMMENT;
 347                         else if (!strchr(WHITESPACE, c)) {
 348                                 state = KEY;
 349                                 last_key_whitespace = (size_t) -1;
 350
 351                                 if (!GREEDY_REALLOC(key, key_alloc, n_key+2)) {
 352                                         r = -ENOMEM;
 353                                         goto fail;
 354                                 }
 355
 356                                 key[n_key++] = c;
 357                         }
 358                         break;
 359
 360                 case KEY:
 361                         if (strchr(newline, c)) {
 362                                 state = PRE_KEY;
 363                                 line++;
 364                                 n_key = 0;
 365                         } else if (c == '=') {
 366                                 state = PRE_VALUE;
 367                                 last_value_whitespace = (size_t) -1;
 368                         } else {
 369                                 if (!strchr(WHITESPACE, c))
 370                                         last_key_whitespace = (size_t) -1;
 371                                 else if (last_key_whitespace == (size_t) -1)
 372                                          last_key_whitespace = n_key;
 373
 374                                 if (!GREEDY_REALLOC(key, key_alloc, n_key+2)) {
 375                                         r = -ENOMEM;
 376                                         goto fail;
 377                                 }
 378
 379                                 key[n_key++] = c;
 380                         }
 381
 382                         break;
 383
 384                 case PRE_VALUE:
 385                         if (strchr(newline, c)) {
 386                                 state = PRE_KEY;
 387                                 line++;
 388                                 key[n_key] = 0;
 389
 390                                 if (value)
 391                                         value[n_value] = 0;
 392
 393                                 /* strip trailing whitespace from key */
 394                                 if (last_key_whitespace != (size_t) -1)
 395                                         key[last_key_whitespace] = 0;
 396
 397                                 r = push(fname, line, key, value, userdata, n_pushed);
 398                                 if (r < 0)
 399                                         goto fail;
 400
 401                                 n_key = 0;
 402                                 value = NULL;
 403                                 value_alloc = n_value = 0;
 404
 405                         } else if (c == '\'')
 406                                 state = SINGLE_QUOTE_VALUE;
 407                         else if (c == '\"')
 408                                 state = DOUBLE_QUOTE_VALUE;
 409                         else if (c == '\\')
 410                                 state = VALUE_ESCAPE;
 411                         else if (!strchr(WHITESPACE, c)) {
 412                                 state = VALUE;
 413
 414                                 if (!GREEDY_REALLOC(value, value_alloc, n_value+2)) {
 415                                         r = -ENOMEM;
 416                                         goto fail;
 417                                 }
 418
 419                                 value[n_value++] = c;
 420                         }
 421
 422                         break;
 423
 424                 case VALUE:
 425                         if (strchr(newline, c)) {
 426                                 state = PRE_KEY;
 427                                 line++;
 428
 429                                 key[n_key] = 0;
 430
 431                                 if (value)
 432                                         value[n_value] = 0;
 433
 434                                 /* Chomp off trailing whitespace from value */
 435                                 if (last_value_whitespace != (size_t) -1)
 436                                         value[last_value_whitespace] = 0;
 437
 438                                 /* strip trailing whitespace from key */
 439                                 if (last_key_whitespace != (size_t) -1)
 440                                         key[last_key_whitespace] = 0;
 441
 442                                 r = push(fname, line, key, value, userdata, n_pushed);
 443                                 if (r < 0)
 444                                         goto fail;
 445
 446                                 n_key = 0;
 447                                 value = NULL;
 448                                 value_alloc = n_value = 0;
 449
 450                         } else if (c == '\\') {
 451                                 state = VALUE_ESCAPE;
 452                                 last_value_whitespace = (size_t) -1;
 453                         } else {
 454                                 if (!strchr(WHITESPACE, c))
 455                                         last_value_whitespace = (size_t) -1;
 456                                 else if (last_value_whitespace == (size_t) -1)
 457                                         last_value_whitespace = n_value;
 458
 459                                 if (!GREEDY_REALLOC(value, value_alloc, n_value+2)) {
 460                                         r = -ENOMEM;
 461                                         goto fail;
 462                                 }
 463
 464                                 value[n_value++] = c;
 465                         }
 466
 467                         break;
 468
 469                 case VALUE_ESCAPE:
 470                         state = VALUE;
 471
 472                         if (!strchr(newline, c)) {
 473                                 /* Escaped newlines we eat up entirely */
 474                                 if (!GREEDY_REALLOC(value, value_alloc, n_value+2)) {
 475                                         r = -ENOMEM;
 476                                         goto fail;
 477                                 }
 478
 479                                 value[n_value++] = c;
 480                         }
 481                         break;
 482
 483                 case SINGLE_QUOTE_VALUE:
 484                         if (c == '\'')
 485                                 state = PRE_VALUE;
 486                         else if (c == '\\')
 487                                 state = SINGLE_QUOTE_VALUE_ESCAPE;
 488                         else {
 489                                 if (!GREEDY_REALLOC(value, value_alloc, n_value+2)) {
 490                                         r = -ENOMEM;
 491                                         goto fail;
 492                                 }
 493
 494                                 value[n_value++] = c;
 495                         }
 496
 497                         break;
 498
 499                 case SINGLE_QUOTE_VALUE_ESCAPE:
 500                         state = SINGLE_QUOTE_VALUE;
 501
 502                         if (!strchr(newline, c)) {
 503                                 if (!GREEDY_REALLOC(value, value_alloc, n_value+2)) {
 504                                         r = -ENOMEM;
 505                                         goto fail;
 506                                 }
 507
 508                                 value[n_value++] = c;
 509                         }
 510                         break;
 511
 512                 case DOUBLE_QUOTE_VALUE:
 513                         if (c == '\"')
 514                                 state = PRE_VALUE;
 515                         else if (c == '\\')
 516                                 state = DOUBLE_QUOTE_VALUE_ESCAPE;
 517                         else {
 518                                 if (!GREEDY_REALLOC(value, value_alloc, n_value+2)) {
 519                                         r = -ENOMEM;
 520                                         goto fail;
 521                                 }
 522
 523                                 value[n_value++] = c;
 524                         }
 525
 526                         break;
 527
 528                 case DOUBLE_QUOTE_VALUE_ESCAPE:
 529                         state = DOUBLE_QUOTE_VALUE;
 530
 531                         if (!strchr(newline, c)) {
 532                                 if (!GREEDY_REALLOC(value, value_alloc, n_value+2)) {
 533                                         r = -ENOMEM;
 534                                         goto fail;
 535                                 }
 536
 537                                 value[n_value++] = c;
 538                         }
 539                         break;
 540
 541                 case COMMENT:
 542                         if (c == '\\')
 543                                 state = COMMENT_ESCAPE;
 544                         else if (strchr(newline, c)) {
 545                                 state = PRE_KEY;
 546                                 line++;
 547                         }
 548                         break;
 549
 550                 case COMMENT_ESCAPE:
 551                         state = COMMENT;
 552                         break;
 553                 }
 554         }
 555
 556         if (state == PRE_VALUE ||
 557             state == VALUE ||
 558             state == VALUE_ESCAPE ||
 559             state == SINGLE_QUOTE_VALUE ||
 560             state == SINGLE_QUOTE_VALUE_ESCAPE ||
 561             state == DOUBLE_QUOTE_VALUE ||
 562             state == DOUBLE_QUOTE_VALUE_ESCAPE) {
 563
 564                 key[n_key] = 0;
 565
 566                 if (value)
 567                         value[n_value] = 0;
 568
 569                 if (state == VALUE)
 570                         if (last_value_whitespace != (size_t) -1)
 571                                 value[last_value_whitespace] = 0;
 572
 573                 /* strip trailing whitespace from key */
 574                 if (last_key_whitespace != (size_t) -1)
 575                         key[last_key_whitespace] = 0;
 576
 577                 r = push(fname, line, key, value, userdata, n_pushed);
 578                 if (r < 0)
 579                         goto fail;
 580         }
 581
 582         return 0;
 583
 584 fail:
 585         free(value);
 586         return r;
 587 }
 588
 589 static int parse_env_file_push(
 590                 const char *filename, unsigned line,
 591                 const char *key, char *value,
 592                 void *userdata,
 593                 int *n_pushed) {
 594
 595         const char *k;
 596         va_list aq, *ap = userdata;
 597
 598         if (!utf8_is_valid(key)) {
 599                 _cleanup_free_ char *p = NULL;
 600
 601                 p = utf8_escape_invalid(key);
 602                 log_error("%s:%u: invalid UTF-8 in key '%s', ignoring.", strna(filename), line, p);
 603                 return -EINVAL;
 604         }
 605
 606         if (value && !utf8_is_valid(value)) {
 607                 _cleanup_free_ char *p = NULL;
 608
 609                 p = utf8_escape_invalid(value);
 610                 log_error("%s:%u: invalid UTF-8 value for key %s: '%s', ignoring.", strna(filename), line, key, p);
 611                 return -EINVAL;
 612         }
 613
 614         va_copy(aq, *ap);
 615
 616         while ((k = va_arg(aq, const char *))) {
 617                 char **v;
 618
 619                 v = va_arg(aq, char **);
 620
 621                 if (streq(key, k)) {
 622                         va_end(aq);
 623                         free(*v);
 624                         *v = value;
 625
 626                         if (n_pushed)
 627                                 (*n_pushed)++;
 628
 629                         return 1;
 630                 }
 631         }
 632
 633         va_end(aq);
 634         free(value);
 635
 636         return 0;
 637 }
 638
 639 int parse_env_file(
 640                 const char *fname,
 641                 const char *newline, ...) {
 642
 643         va_list ap;
 644         int r, n_pushed = 0;
 645
 646         if (!newline)
 647                 newline = NEWLINE;
 648
 649         va_start(ap, newline);
 650         r = parse_env_file_internal(NULL, fname, newline, parse_env_file_push, &ap, &n_pushed);
 651         va_end(ap);
 652
 653         return r < 0 ? r : n_pushed;
 654 }
 655
 656 static int load_env_file_push(
 657                 const char *filename, unsigned line,
 658                 const char *key, char *value,
 659                 void *userdata,
 660                 int *n_pushed) {
 661         char ***m = userdata;
 662         char *p;
 663         int r;
 664
 665         if (!utf8_is_valid(key)) {
 666                 _cleanup_free_ char *t = utf8_escape_invalid(key);
 667
 668                 log_error("%s:%u: invalid UTF-8 for key '%s', ignoring.", strna(filename), line, t);
 669                 return -EINVAL;
 670         }
 671
 672         if (value && !utf8_is_valid(value)) {
 673                 _cleanup_free_ char *t = utf8_escape_invalid(value);
 674
 675                 log_error("%s:%u: invalid UTF-8 value for key %s: '%s', ignoring.", strna(filename), line, key, t);
 676                 return -EINVAL;
 677         }
 678
 679         p = strjoin(key, "=", strempty(value), NULL);
 680         if (!p)
 681                 return -ENOMEM;
 682
 683         r = strv_consume(m, p);
 684         if (r < 0)
 685                 return r;
 686
 687         if (n_pushed)
 688                 (*n_pushed)++;
 689
 690         free(value);
 691         return 0;
 692 }
 693
 694 int load_env_file(FILE *f, const char *fname, const char *newline, char ***rl) {
 695         char **m = NULL;
 696         int r;
 697
 698         if (!newline)
 699                 newline = NEWLINE;
 700
 701         r = parse_env_file_internal(f, fname, newline, load_env_file_push, &m, NULL);
 702         if (r < 0) {
 703                 strv_free(m);
 704                 return r;
 705         }
 706
 707         *rl = m;
 708         return 0;
 709 }
 710
 711 static int load_env_file_push_pairs(
 712                 const char *filename, unsigned line,
 713                 const char *key, char *value,
 714                 void *userdata,
 715                 int *n_pushed) {
 716         char ***m = userdata;
 717         int r;
 718
 719         if (!utf8_is_valid(key)) {
 720                 _cleanup_free_ char *t = utf8_escape_invalid(key);
 721
 722                 log_error("%s:%u: invalid UTF-8 for key '%s', ignoring.", strna(filename), line, t);
 723                 return -EINVAL;
 724         }
 725
 726         if (value && !utf8_is_valid(value)) {
 727                 _cleanup_free_ char *t = utf8_escape_invalid(value);
 728
 729                 log_error("%s:%u: invalid UTF-8 value for key %s: '%s', ignoring.", strna(filename), line, key, t);
 730                 return -EINVAL;
 731         }
 732
 733         r = strv_extend(m, key);
 734         if (r < 0)
 735                 return -ENOMEM;
 736
 737         if (!value) {
 738                 r = strv_extend(m, "");
 739                 if (r < 0)
 740                         return -ENOMEM;
 741         } else {
 742                 r = strv_push(m, value);
 743                 if (r < 0)
 744                         return r;
 745         }
 746
 747         if (n_pushed)
 748                 (*n_pushed)++;
 749
 750         return 0;
 751 }
 752
 753 int load_env_file_pairs(FILE *f, const char *fname, const char *newline, char ***rl) {
 754         char **m = NULL;
 755         int r;
 756
 757         if (!newline)
 758                 newline = NEWLINE;
 759
 760         r = parse_env_file_internal(f, fname, newline, load_env_file_push_pairs, &m, NULL);
 761         if (r < 0) {
 762                 strv_free(m);
 763                 return r;
 764         }
 765
 766         *rl = m;
 767         return 0;
 768 }
 769
 770 static void write_env_var(FILE *f, const char *v) {
 771         const char *p;
 772
 773         p = strchr(v, '=');
 774         if (!p) {
 775                 /* Fallback */
 776                 fputs(v, f);
 777                 fputc('\n', f);
 778                 return;
 779         }
 780
 781         p++;
 782         fwrite(v, 1, p-v, f);
 783
 784         if (string_has_cc(p, NULL) || chars_intersect(p, WHITESPACE SHELL_NEED_QUOTES)) {
 785                 fputc('\"', f);
 786
 787                 for (; *p; p++) {
 788                         if (strchr(SHELL_NEED_ESCAPE, *p))
 789                                 fputc('\\', f);
 790
 791                         fputc(*p, f);
 792                 }
 793
 794                 fputc('\"', f);
 795         } else
 796                 fputs(p, f);
 797
 798         fputc('\n', f);
 799 }
 800
 801 int write_env_file(const char *fname, char **l) {
 802         _cleanup_fclose_ FILE *f = NULL;
 803         _cleanup_free_ char *p = NULL;
 804         char **i;
 805         int r;
 806
 807         assert(fname);
 808
 809         r = fopen_temporary(fname, &f, &p);
 810         if (r < 0)
 811                 return r;
 812
 813         fchmod_umask(fileno(f), 0644);
 814
 815         STRV_FOREACH(i, l)
 816                 write_env_var(f, *i);
 817
 818         r = fflush_and_check(f);
 819         if (r >= 0) {
 820                 if (rename(p, fname) >= 0)
 821                         return 0;
 822
 823                 r = -errno;
 824         }
 825
 826         unlink(p);
 827         return r;
 828 }
 829
 830 int executable_is_script(const char *path, char **interpreter) {
 831         int r;
 832         _cleanup_free_ char *line = NULL;
 833         int len;
 834         char *ans;
 835
 836         assert(path);
 837
 838         r = read_one_line_file(path, &line);
 839         if (r < 0)
 840                 return r;
 841
 842         if (!startswith(line, "#!"))
 843                 return 0;
 844
 845         ans = strstrip(line + 2);
 846         len = strcspn(ans, " \t");
 847
 848         if (len == 0)
 849                 return 0;
 850
 851         ans = strndup(ans, len);
 852         if (!ans)
 853                 return -ENOMEM;
 854
 855         *interpreter = ans;
 856         return 1;
 857 }
 858
 859 /**
 860  * Retrieve one field from a file like /proc/self/status.  pattern
 861  * should not include whitespace or the delimiter (':'). pattern matches only
 862  * the beginning of a line. Whitespace before ':' is skipped. Whitespace and
 863  * zeros after the ':' will be skipped. field must be freed afterwards.
 864  * terminator specifies the terminating characters of the field value (not
 865  * included in the value).
 866  */
 867 int get_proc_field(const char *filename, const char *pattern, const char *terminator, char **field) {
 868         _cleanup_free_ char *status = NULL;
 869         char *t, *f;
 870         size_t len;
 871         int r;
 872
 873         assert(terminator);
 874         assert(filename);
 875         assert(pattern);
 876         assert(field);
 877
 878         r = read_full_file(filename, &status, NULL);
 879         if (r < 0)
 880                 return r;
 881
 882         t = status;
 883
 884         do {
 885                 bool pattern_ok;
 886
 887                 do {
 888                         t = strstr(t, pattern);
 889                         if (!t)
 890                                 return -ENOENT;
 891
 892                         /* Check that pattern occurs in beginning of line. */
 893                         pattern_ok = (t == status || t[-1] == '\n');
 894
 895                         t += strlen(pattern);
 896
 897                 } while (!pattern_ok);
 898
 899                 t += strspn(t, " \t");
 900                 if (!*t)
 901                         return -ENOENT;
 902
 903         } while (*t != ':');
 904
 905         t++;
 906
 907         if (*t) {
 908                 t += strspn(t, " \t");
 909
 910                 /* Also skip zeros, because when this is used for
 911                  * capabilities, we don't want the zeros. This way the
 912                  * same capability set always maps to the same string,
 913                  * irrespective of the total capability set size. For
 914                  * other numbers it shouldn't matter. */
 915                 t += strspn(t, "0");
 916                 /* Back off one char if there's nothing but whitespace
 917                    and zeros */
 918                 if (!*t || isspace(*t))
 919                         t--;
 920         }
 921
 922         len = strcspn(t, terminator);
 923
 924         f = strndup(t, len);
 925         if (!f)
 926                 return -ENOMEM;
 927
 928         *field = f;
 929         return 0;
 930 }
 931
 932 DIR *xopendirat(int fd, const char *name, int flags) {
 933         int nfd;
 934         DIR *d;
 935
 936         assert(!(flags & O_CREAT));
 937
 938         nfd = openat(fd, name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|flags, 0);
 939         if (nfd < 0)
 940                 return NULL;
 941
 942         d = fdopendir(nfd);
 943         if (!d) {
 944                 safe_close(nfd);
 945                 return NULL;
 946         }
 947
 948         return d;
 949 }
 950
 951 static int search_and_fopen_internal(const char *path, const char *mode, const char *root, char **search, FILE **_f) {
 952         char **i;
 953
 954         assert(path);
 955         assert(mode);
 956         assert(_f);
 957
 958         if (!path_strv_resolve_uniq(search, root))
 959                 return -ENOMEM;
 960
 961         STRV_FOREACH(i, search) {
 962                 _cleanup_free_ char *p = NULL;
 963                 FILE *f;
 964
 965                 if (root)
 966                         p = strjoin(root, *i, "/", path, NULL);
 967                 else
 968                         p = strjoin(*i, "/", path, NULL);
 969                 if (!p)
 970                         return -ENOMEM;
 971
 972                 f = fopen(p, mode);
 973                 if (f) {
 974                         *_f = f;
 975                         return 0;
 976                 }
 977
 978                 if (errno != ENOENT)
 979                         return -errno;
 980         }
 981
 982         return -ENOENT;
 983 }
 984
 985 int search_and_fopen(const char *path, const char *mode, const char *root, const char **search, FILE **_f) {
 986         _cleanup_strv_free_ char **copy = NULL;
 987
 988         assert(path);
 989         assert(mode);
 990         assert(_f);
 991
 992         if (path_is_absolute(path)) {
 993                 FILE *f;
 994
 995                 f = fopen(path, mode);
 996                 if (f) {
 997                         *_f = f;
 998                         return 0;
 999                 }
1000
1001                 return -errno;
1002         }
1003
1004         copy = strv_copy((char**) search);
1005         if (!copy)
1006                 return -ENOMEM;
1007
1008         return search_and_fopen_internal(path, mode, root, copy, _f);
1009 }
1010
1011 int search_and_fopen_nulstr(const char *path, const char *mode, const char *root, const char *search, FILE **_f) {
1012         _cleanup_strv_free_ char **s = NULL;
1013
1014         if (path_is_absolute(path)) {
1015                 FILE *f;
1016
1017                 f = fopen(path, mode);
1018                 if (f) {
1019                         *_f = f;
1020                         return 0;
1021                 }
1022
1023                 return -errno;
1024         }
1025
1026         s = strv_split_nulstr(search);
1027         if (!s)
1028                 return -ENOMEM;
1029
1030         return search_and_fopen_internal(path, mode, root, s, _f);
1031 }
1032
1033 int fopen_temporary(const char *path, FILE **_f, char **_temp_path) {
1034         FILE *f;
1035         char *t;
1036         int r, fd;
1037
1038         assert(path);
1039         assert(_f);
1040         assert(_temp_path);
1041
1042         r = tempfn_xxxxxx(path, NULL, &t);
1043         if (r < 0)
1044                 return r;
1045
1046         fd = mkostemp_safe(t, O_WRONLY|O_CLOEXEC);
1047         if (fd < 0) {
1048                 free(t);
1049                 return -errno;
1050         }
1051
1052         f = fdopen(fd, "we");
1053         if (!f) {
1054                 unlink_noerrno(t);
1055                 free(t);
1056                 safe_close(fd);
1057                 return -errno;
1058         }
1059
1060         *_f = f;
1061         *_temp_path = t;
1062
1063         return 0;
1064 }
1065
1066 int fflush_and_check(FILE *f) {
1067         assert(f);
1068
1069         errno = 0;
1070         fflush(f);
1071
1072         if (ferror(f))
1073                 return errno > 0 ? -errno : -EIO;
1074
1075         return 0;
1076 }
1077
1078 /* This is much like mkostemp() but is subject to umask(). */
1079 int mkostemp_safe(char *pattern, int flags) {
1080         _cleanup_umask_ mode_t u = 0;
1081         int fd;
1082
1083         assert(pattern);
1084
1085         u = umask(077);
1086
1087         fd = mkostemp(pattern, flags);
1088         if (fd < 0)
1089                 return -errno;
1090
1091         return fd;
1092 }
1093
1094 int tempfn_xxxxxx(const char *p, const char *extra, char **ret) {
1095         const char *fn;
1096         char *t;
1097
1098         assert(p);
1099         assert(ret);
1100
1101         /*
1102          * Turns this:
1103          *         /foo/bar/waldo
1104          *
1105          * Into this:
1106          *         /foo/bar/.#<extra>waldoXXXXXX
1107          */
1108
1109         fn = basename(p);
1110         if (!filename_is_valid(fn))
1111                 return -EINVAL;
1112
1113         if (extra == NULL)
1114                 extra = "";
1115
1116         t = new(char, strlen(p) + 2 + strlen(extra) + 6 + 1);
1117         if (!t)
1118                 return -ENOMEM;
1119
1120         strcpy(stpcpy(stpcpy(stpcpy(mempcpy(t, p, fn - p), ".#"), extra), fn), "XXXXXX");
1121
1122         *ret = path_kill_slashes(t);
1123         return 0;
1124 }
1125
1126 int tempfn_random(const char *p, const char *extra, char **ret) {
1127         const char *fn;
1128         char *t, *x;
1129         uint64_t u;
1130         unsigned i;
1131
1132         assert(p);
1133         assert(ret);
1134
1135         /*
1136          * Turns this:
1137          *         /foo/bar/waldo
1138          *
1139          * Into this:
1140          *         /foo/bar/.#<extra>waldobaa2a261115984a9
1141          */
1142
1143         fn = basename(p);
1144         if (!filename_is_valid(fn))
1145                 return -EINVAL;
1146
1147         if (!extra)
1148                 extra = "";
1149
1150         t = new(char, strlen(p) + 2 + strlen(extra) + 16 + 1);
1151         if (!t)
1152                 return -ENOMEM;
1153
1154         x = stpcpy(stpcpy(stpcpy(mempcpy(t, p, fn - p), ".#"), extra), fn);
1155
1156         u = random_u64();
1157         for (i = 0; i < 16; i++) {
1158                 *(x++) = hexchar(u & 0xF);
1159                 u >>= 4;
1160         }
1161
1162         *x = 0;
1163
1164         *ret = path_kill_slashes(t);
1165         return 0;
1166 }
1167
1168 int tempfn_random_child(const char *p, const char *extra, char **ret) {
1169         char *t, *x;
1170         uint64_t u;
1171         unsigned i;
1172         int r;
1173
1174         assert(ret);
1175
1176         /* Turns this:
1177          *         /foo/bar/waldo
1178          * Into this:
1179          *         /foo/bar/waldo/.#<extra>3c2b6219aa75d7d0
1180          */
1181
1182         if (!p) {
1183                 r = tmp_dir(&p);
1184                 if (r < 0)
1185                         return r;
1186         }
1187
1188         if (!extra)
1189                 extra = "";
1190
1191         t = new(char, strlen(p) + 3 + strlen(extra) + 16 + 1);
1192         if (!t)
1193                 return -ENOMEM;
1194
1195         x = stpcpy(stpcpy(stpcpy(t, p), "/.#"), extra);
1196
1197         u = random_u64();
1198         for (i = 0; i < 16; i++) {
1199                 *(x++) = hexchar(u & 0xF);
1200                 u >>= 4;
1201         }
1202
1203         *x = 0;
1204
1205         *ret = path_kill_slashes(t);
1206         return 0;
1207 }
1208
1209 int write_timestamp_file_atomic(const char *fn, usec_t n) {
1210         char ln[DECIMAL_STR_MAX(n)+2];
1211
1212         /* Creates a "timestamp" file, that contains nothing but a
1213          * usec_t timestamp, formatted in ASCII. */
1214
1215         if (n <= 0 || n >= USEC_INFINITY)
1216                 return -ERANGE;
1217
1218         xsprintf(ln, USEC_FMT "\n", n);
1219
1220         return write_string_file(fn, ln, WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_ATOMIC);
1221 }
1222
1223 int read_timestamp_file(const char *fn, usec_t *ret) {
1224         _cleanup_free_ char *ln = NULL;
1225         uint64_t t;
1226         int r;
1227
1228         r = read_one_line_file(fn, &ln);
1229         if (r < 0)
1230                 return r;
1231
1232         r = safe_atou64(ln, &t);
1233         if (r < 0)
1234                 return r;
1235
1236         if (t <= 0 || t >= (uint64_t) USEC_INFINITY)
1237                 return -ERANGE;
1238
1239         *ret = (usec_t) t;
1240         return 0;
1241 }
1242
1243 int fputs_with_space(FILE *f, const char *s, const char *separator, bool *space) {
1244         int r;
1245
1246         assert(s);
1247
1248         /* Outputs the specified string with fputs(), but optionally prefixes it with a separator. The *space parameter
1249          * when specified shall initially point to a boolean variable initialized to false. It is set to true after the
1250          * first invocation. This call is supposed to be use in loops, where a separator shall be inserted between each
1251          * element, but not before the first one. */
1252
1253         if (!f)
1254                 f = stdout;
1255
1256         if (space) {
1257                 if (!separator)
1258                         separator = " ";
1259
1260                 if (*space) {
1261                         r = fputs(separator, f);
1262                         if (r < 0)
1263                                 return r;
1264                 }
1265
1266                 *space = true;
1267         }
1268
1269         return fputs(s, f);
1270 }
1271
1272 int open_tmpfile_unlinkable(const char *directory, int flags) {
1273         char *p;
1274         int fd, r;
1275
1276         if (!directory) {
1277                 r = tmp_dir(&directory);
1278                 if (r < 0)
1279                         return r;
1280         }
1281
1282         /* Returns an unlinked temporary file that cannot be linked into the file system anymore */
1283
1284         /* Try O_TMPFILE first, if it is supported */
1285         fd = open(directory, flags|O_TMPFILE|O_EXCL, S_IRUSR|S_IWUSR);
1286         if (fd >= 0)
1287                 return fd;
1288
1289         /* Fall back to unguessable name + unlinking */
1290         p = strjoina(directory, "/systemd-tmp-XXXXXX");
1291
1292         fd = mkostemp_safe(p, flags);
1293         if (fd < 0)
1294                 return fd;
1295
1296         (void) unlink(p);
1297
1298         return fd;
1299 }
1300
1301 int open_tmpfile_linkable(const char *target, int flags, char **ret_path) {
1302         _cleanup_free_ char *tmp = NULL;
1303         int r, fd;
1304
1305         assert(target);
1306         assert(ret_path);
1307
1308         /* Don't allow O_EXCL, as that has a special meaning for O_TMPFILE */
1309         assert((flags & O_EXCL) == 0);
1310
1311         /* Creates a temporary file, that shall be renamed to "target" later. If possible, this uses O_TMPFILE – in
1312          * which case "ret_path" will be returned as NULL. If not possible a the tempoary path name used is returned in
1313          * "ret_path". Use link_tmpfile() below to rename the result after writing the file in full. */
1314
1315         {
1316                 _cleanup_free_ char *dn = NULL;
1317
1318                 dn = dirname_malloc(target);
1319                 if (!dn)
1320                         return -ENOMEM;
1321
1322                 fd = open(dn, O_TMPFILE|flags, 0640);
1323                 if (fd >= 0) {
1324                         *ret_path = NULL;
1325                         return fd;
1326                 }
1327
1328                 log_debug_errno(errno, "Failed to use O_TMPFILE on %s: %m", dn);
1329         }
1330
1331         r = tempfn_random(target, NULL, &tmp);
1332         if (r < 0)
1333                 return r;
1334
1335         fd = open(tmp, O_CREAT|O_EXCL|O_NOFOLLOW|O_NOCTTY|flags, 0640);
1336         if (fd < 0)
1337                 return -errno;
1338
1339         *ret_path = tmp;
1340         tmp = NULL;
1341
1342         return fd;
1343 }
1344
1345 int link_tmpfile(int fd, const char *path, const char *target) {
1346
1347         assert(fd >= 0);
1348         assert(target);
1349
1350         /* Moves a temporary file created with open_tmpfile() above into its final place. if "path" is NULL an fd
1351          * created with O_TMPFILE is assumed, and linkat() is used. Otherwise it is assumed O_TMPFILE is not supported
1352          * on the directory, and renameat2() is used instead.
1353          *
1354          * Note that in both cases we will not replace existing files. This is because linkat() does not support this
1355          * operation currently (renameat2() does), and there is no nice way to emulate this. */
1356
1357         if (path) {
1358                 if (rename_noreplace(AT_FDCWD, path, AT_FDCWD, target) < 0)
1359                         return -errno;
1360         } else {
1361                 char proc_fd_path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(fd) + 1];
1362
1363                 xsprintf(proc_fd_path, "/proc/self/fd/%i", fd);
1364
1365                 if (linkat(AT_FDCWD, proc_fd_path, AT_FDCWD, target, AT_SYMLINK_FOLLOW) < 0)
1366                         return -errno;
1367         }
1368
1369         return 0;
1370 }
1371
1372 int read_nul_string(FILE *f, char **ret) {
1373         _cleanup_free_ char *x = NULL;
1374         size_t allocated = 0, n = 0;
1375
1376         assert(f);
1377         assert(ret);
1378
1379         /* Reads a NUL-terminated string from the specified file. */
1380
1381         for (;;) {
1382                 int c;
1383
1384                 if (!GREEDY_REALLOC(x, allocated, n+2))
1385                         return -ENOMEM;
1386
1387                 c = fgetc(f);
1388                 if (c == 0) /* Terminate at NUL byte */
1389                         break;
1390                 if (c == EOF) {
1391                         if (ferror(f))
1392                                 return -errno;
1393                         break; /* Terminate at EOF */
1394                 }
1395
1396                 x[n++] = (char) c;
1397         }
1398
1399         if (x)
1400                 x[n] = 0;
1401         else {
1402                 x = new0(char, 1);
1403                 if (!x)
1404                         return -ENOMEM;
1405         }
1406
1407         *ret = x;
1408         x = NULL;
1409
1410         return 0;
1411 }