src/basic/string-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2010 Lennart Poettering
   6 ***/
   7
   8 #include <errno.h>
   9 #include <stdarg.h>
  10 #include <stdint.h>
  11 #include <stdio.h>
  12 #include <stdio_ext.h>
  13 #include <stdlib.h>
  14 #include <string.h>
  15
  16 #include "alloc-util.h"
  17 #include "gunicode.h"
  18 #include "locale-util.h"
  19 #include "macro.h"
  20 #include "string-util.h"
  21 #include "terminal-util.h"
  22 #include "utf8.h"
  23 #include "util.h"
  24 #include "fileio.h"
  25
  26 int strcmp_ptr(const char *a, const char *b) {
  27
  28         /* Like strcmp(), but tries to make sense of NULL pointers */
  29         if (a && b)
  30                 return strcmp(a, b);
  31
  32         if (!a && b)
  33                 return -1;
  34
  35         if (a && !b)
  36                 return 1;
  37
  38         return 0;
  39 }
  40
  41 char* endswith(const char *s, const char *postfix) {
  42         size_t sl, pl;
  43
  44         assert(s);
  45         assert(postfix);
  46
  47         sl = strlen(s);
  48         pl = strlen(postfix);
  49
  50         if (pl == 0)
  51                 return (char*) s + sl;
  52
  53         if (sl < pl)
  54                 return NULL;
  55
  56         if (memcmp(s + sl - pl, postfix, pl) != 0)
  57                 return NULL;
  58
  59         return (char*) s + sl - pl;
  60 }
  61
  62 char* endswith_no_case(const char *s, const char *postfix) {
  63         size_t sl, pl;
  64
  65         assert(s);
  66         assert(postfix);
  67
  68         sl = strlen(s);
  69         pl = strlen(postfix);
  70
  71         if (pl == 0)
  72                 return (char*) s + sl;
  73
  74         if (sl < pl)
  75                 return NULL;
  76
  77         if (strcasecmp(s + sl - pl, postfix) != 0)
  78                 return NULL;
  79
  80         return (char*) s + sl - pl;
  81 }
  82
  83 char* first_word(const char *s, const char *word) {
  84         size_t sl, wl;
  85         const char *p;
  86
  87         assert(s);
  88         assert(word);
  89
  90         /* Checks if the string starts with the specified word, either
  91          * followed by NUL or by whitespace. Returns a pointer to the
  92          * NUL or the first character after the whitespace. */
  93
  94         sl = strlen(s);
  95         wl = strlen(word);
  96
  97         if (sl < wl)
  98                 return NULL;
  99
 100         if (wl == 0)
 101                 return (char*) s;
 102
 103         if (memcmp(s, word, wl) != 0)
 104                 return NULL;
 105
 106         p = s + wl;
 107         if (*p == 0)
 108                 return (char*) p;
 109
 110         if (!strchr(WHITESPACE, *p))
 111                 return NULL;
 112
 113         p += strspn(p, WHITESPACE);
 114         return (char*) p;
 115 }
 116
 117 static size_t strcspn_escaped(const char *s, const char *reject) {
 118         bool escaped = false;
 119         int n;
 120
 121         for (n=0; s[n]; n++) {
 122                 if (escaped)
 123                         escaped = false;
 124                 else if (s[n] == '\\')
 125                         escaped = true;
 126                 else if (strchr(reject, s[n]))
 127                         break;
 128         }
 129
 130         /* if s ends in \, return index of previous char */
 131         return n - escaped;
 132 }
 133
 134 /* Split a string into words. */
 135 const char* split(const char **state, size_t *l, const char *separator, bool quoted) {
 136         const char *current;
 137
 138         current = *state;
 139
 140         if (!*current) {
 141                 assert(**state == '\0');
 142                 return NULL;
 143         }
 144
 145         current += strspn(current, separator);
 146         if (!*current) {
 147                 *state = current;
 148                 return NULL;
 149         }
 150
 151         if (quoted && strchr("\'\"", *current)) {
 152                 char quotechars[2] = {*current, '\0'};
 153
 154                 *l = strcspn_escaped(current + 1, quotechars);
 155                 if (current[*l + 1] == '\0' || current[*l + 1] != quotechars[0] ||
 156                     (current[*l + 2] && !strchr(separator, current[*l + 2]))) {
 157                         /* right quote missing or garbage at the end */
 158                         *state = current;
 159                         return NULL;
 160                 }
 161                 *state = current++ + *l + 2;
 162         } else if (quoted) {
 163                 *l = strcspn_escaped(current, separator);
 164                 if (current[*l] && !strchr(separator, current[*l])) {
 165                         /* unfinished escape */
 166                         *state = current;
 167                         return NULL;
 168                 }
 169                 *state = current + *l;
 170         } else {
 171                 *l = strcspn(current, separator);
 172                 *state = current + *l;
 173         }
 174
 175         return current;
 176 }
 177
 178 char *strnappend(const char *s, const char *suffix, size_t b) {
 179         size_t a;
 180         char *r;
 181
 182         if (!s && !suffix)
 183                 return strdup("");
 184
 185         if (!s)
 186                 return strndup(suffix, b);
 187
 188         if (!suffix)
 189                 return strdup(s);
 190
 191         assert(s);
 192         assert(suffix);
 193
 194         a = strlen(s);
 195         if (b > ((size_t) -1) - a)
 196                 return NULL;
 197
 198         r = new(char, a+b+1);
 199         if (!r)
 200                 return NULL;
 201
 202         memcpy(r, s, a);
 203         memcpy(r+a, suffix, b);
 204         r[a+b] = 0;
 205
 206         return r;
 207 }
 208
 209 char *strappend(const char *s, const char *suffix) {
 210         return strnappend(s, suffix, strlen_ptr(suffix));
 211 }
 212
 213 char *strjoin_real(const char *x, ...) {
 214         va_list ap;
 215         size_t l;
 216         char *r, *p;
 217
 218         va_start(ap, x);
 219
 220         if (x) {
 221                 l = strlen(x);
 222
 223                 for (;;) {
 224                         const char *t;
 225                         size_t n;
 226
 227                         t = va_arg(ap, const char *);
 228                         if (!t)
 229                                 break;
 230
 231                         n = strlen(t);
 232                         if (n > ((size_t) -1) - l) {
 233                                 va_end(ap);
 234                                 return NULL;
 235                         }
 236
 237                         l += n;
 238                 }
 239         } else
 240                 l = 0;
 241
 242         va_end(ap);
 243
 244         r = new(char, l+1);
 245         if (!r)
 246                 return NULL;
 247
 248         if (x) {
 249                 p = stpcpy(r, x);
 250
 251                 va_start(ap, x);
 252
 253                 for (;;) {
 254                         const char *t;
 255
 256                         t = va_arg(ap, const char *);
 257                         if (!t)
 258                                 break;
 259
 260                         p = stpcpy(p, t);
 261                 }
 262
 263                 va_end(ap);
 264         } else
 265                 r[0] = 0;
 266
 267         return r;
 268 }
 269
 270 char *strstrip(char *s) {
 271         char *e;
 272
 273         if (!s)
 274                 return NULL;
 275
 276         /* Drops trailing whitespace. Modifies the string in
 277          * place. Returns pointer to first non-space character */
 278
 279         s += strspn(s, WHITESPACE);
 280
 281         for (e = strchr(s, 0); e > s; e --)
 282                 if (!strchr(WHITESPACE, e[-1]))
 283                         break;
 284
 285         *e = 0;
 286
 287         return s;
 288 }
 289
 290 char *delete_chars(char *s, const char *bad) {
 291         char *f, *t;
 292
 293         /* Drops all specified bad characters, regardless where in the string */
 294
 295         if (!s)
 296                 return NULL;
 297
 298         if (!bad)
 299                 bad = WHITESPACE;
 300
 301         for (f = s, t = s; *f; f++) {
 302                 if (strchr(bad, *f))
 303                         continue;
 304
 305                 *(t++) = *f;
 306         }
 307
 308         *t = 0;
 309
 310         return s;
 311 }
 312
 313 char *delete_trailing_chars(char *s, const char *bad) {
 314         char *p, *c = s;
 315
 316         /* Drops all specified bad characters, at the end of the string */
 317
 318         if (!s)
 319                 return NULL;
 320
 321         if (!bad)
 322                 bad = WHITESPACE;
 323
 324         for (p = s; *p; p++)
 325                 if (!strchr(bad, *p))
 326                         c = p + 1;
 327
 328         *c = 0;
 329
 330         return s;
 331 }
 332
 333 char *truncate_nl(char *s) {
 334         assert(s);
 335
 336         s[strcspn(s, NEWLINE)] = 0;
 337         return s;
 338 }
 339
 340 char ascii_tolower(char x) {
 341
 342         if (x >= 'A' && x <= 'Z')
 343                 return x - 'A' + 'a';
 344
 345         return x;
 346 }
 347
 348 char ascii_toupper(char x) {
 349
 350         if (x >= 'a' && x <= 'z')
 351                 return x - 'a' + 'A';
 352
 353         return x;
 354 }
 355
 356 char *ascii_strlower(char *t) {
 357         char *p;
 358
 359         assert(t);
 360
 361         for (p = t; *p; p++)
 362                 *p = ascii_tolower(*p);
 363
 364         return t;
 365 }
 366
 367 char *ascii_strupper(char *t) {
 368         char *p;
 369
 370         assert(t);
 371
 372         for (p = t; *p; p++)
 373                 *p = ascii_toupper(*p);
 374
 375         return t;
 376 }
 377
 378 char *ascii_strlower_n(char *t, size_t n) {
 379         size_t i;
 380
 381         if (n <= 0)
 382                 return t;
 383
 384         for (i = 0; i < n; i++)
 385                 t[i] = ascii_tolower(t[i]);
 386
 387         return t;
 388 }
 389
 390 int ascii_strcasecmp_n(const char *a, const char *b, size_t n) {
 391
 392         for (; n > 0; a++, b++, n--) {
 393                 int x, y;
 394
 395                 x = (int) (uint8_t) ascii_tolower(*a);
 396                 y = (int) (uint8_t) ascii_tolower(*b);
 397
 398                 if (x != y)
 399                         return x - y;
 400         }
 401
 402         return 0;
 403 }
 404
 405 int ascii_strcasecmp_nn(const char *a, size_t n, const char *b, size_t m) {
 406         int r;
 407
 408         r = ascii_strcasecmp_n(a, b, MIN(n, m));
 409         if (r != 0)
 410                 return r;
 411
 412         if (n < m)
 413                 return -1;
 414         else if (n > m)
 415                 return 1;
 416         else
 417                 return 0;
 418 }
 419
 420 bool chars_intersect(const char *a, const char *b) {
 421         const char *p;
 422
 423         /* Returns true if any of the chars in a are in b. */
 424         for (p = a; *p; p++)
 425                 if (strchr(b, *p))
 426                         return true;
 427
 428         return false;
 429 }
 430
 431 bool string_has_cc(const char *p, const char *ok) {
 432         const char *t;
 433
 434         assert(p);
 435
 436         /*
 437          * Check if a string contains control characters. If 'ok' is
 438          * non-NULL it may be a string containing additional CCs to be
 439          * considered OK.
 440          */
 441
 442         for (t = p; *t; t++) {
 443                 if (ok && strchr(ok, *t))
 444                         continue;
 445
 446                 if (*t > 0 && *t < ' ')
 447                         return true;
 448
 449                 if (*t == 127)
 450                         return true;
 451         }
 452
 453         return false;
 454 }
 455
 456 static char *ascii_ellipsize_mem(const char *s, size_t old_length, size_t new_length, unsigned percent) {
 457         size_t x, need_space;
 458         char *r;
 459
 460         assert(s);
 461         assert(percent <= 100);
 462         assert(new_length != (size_t) -1);
 463
 464         if (old_length <= new_length)
 465                 return strndup(s, old_length);
 466
 467         /* Special case short ellipsations */
 468         switch (new_length) {
 469
 470         case 0:
 471                 return strdup("");
 472
 473         case 1:
 474                 if (is_locale_utf8())
 475                         return strdup("…");
 476                 else
 477                         return strdup(".");
 478
 479         case 2:
 480                 if (!is_locale_utf8())
 481                         return strdup("..");
 482
 483                 break;
 484
 485         default:
 486                 break;
 487         }
 488
 489         /* Calculate how much space the ellipsis will take up. If we are in UTF-8 mode we only need space for one
 490          * character ("…"), otherwise for three characters ("..."). Note that in both cases we need 3 bytes of storage,
 491          * either for the UTF-8 encoded character or for three ASCII characters. */
 492         need_space = is_locale_utf8() ? 1 : 3;
 493
 494         r = new(char, new_length+3);
 495         if (!r)
 496                 return NULL;
 497
 498         assert(new_length >= need_space);
 499
 500         x = ((new_length - need_space) * percent + 50) / 100;
 501         assert(x <= new_length - need_space);
 502
 503         memcpy(r, s, x);
 504
 505         if (is_locale_utf8()) {
 506                 r[x+0] = 0xe2; /* tri-dot ellipsis: … */
 507                 r[x+1] = 0x80;
 508                 r[x+2] = 0xa6;
 509         } else {
 510                 r[x+0] = '.';
 511                 r[x+1] = '.';
 512                 r[x+2] = '.';
 513         }
 514
 515         memcpy(r + x + 3,
 516                s + old_length - (new_length - x - need_space),
 517                new_length - x - need_space + 1);
 518
 519         return r;
 520 }
 521
 522 char *ellipsize_mem(const char *s, size_t old_length, size_t new_length, unsigned percent) {
 523         size_t x, k, len, len2;
 524         const char *i, *j;
 525         char *e;
 526         int r;
 527
 528         /* Note that 'old_length' refers to bytes in the string, while 'new_length' refers to character cells taken up
 529          * on screen. This distinction doesn't matter for ASCII strings, but it does matter for non-ASCII UTF-8
 530          * strings.
 531          *
 532          * Ellipsation is done in a locale-dependent way:
 533          * 1. If the string passed in is fully ASCII and the current locale is not UTF-8, three dots are used ("...")
 534          * 2. Otherwise, a unicode ellipsis is used ("…")
 535          *
 536          * In other words: you'll get a unicode ellipsis as soon as either the string contains non-ASCII characters or
 537          * the current locale is UTF-8.
 538          */
 539
 540         assert(s);
 541         assert(percent <= 100);
 542
 543         if (new_length == (size_t) -1)
 544                 return strndup(s, old_length);
 545
 546         if (new_length == 0)
 547                 return strdup("");
 548
 549         /* If no multibyte characters use ascii_ellipsize_mem for speed */
 550         if (ascii_is_valid(s))
 551                 return ascii_ellipsize_mem(s, old_length, new_length, percent);
 552
 553         x = ((new_length - 1) * percent) / 100;
 554         assert(x <= new_length - 1);
 555
 556         k = 0;
 557         for (i = s; k < x && i < s + old_length; i = utf8_next_char(i)) {
 558                 char32_t c;
 559
 560                 r = utf8_encoded_to_unichar(i, &c);
 561                 if (r < 0)
 562                         return NULL;
 563                 k += unichar_iswide(c) ? 2 : 1;
 564         }
 565
 566         if (k > x) /* last character was wide and went over quota */
 567                 x++;
 568
 569         for (j = s + old_length; k < new_length && j > i; ) {
 570                 char32_t c;
 571
 572                 j = utf8_prev_char(j);
 573                 r = utf8_encoded_to_unichar(j, &c);
 574                 if (r < 0)
 575                         return NULL;
 576                 k += unichar_iswide(c) ? 2 : 1;
 577         }
 578         assert(i <= j);
 579
 580         /* we don't actually need to ellipsize */
 581         if (i == j)
 582                 return memdup(s, old_length + 1);
 583
 584         /* make space for ellipsis */
 585         j = utf8_next_char(j);
 586
 587         len = i - s;
 588         len2 = s + old_length - j;
 589         e = new(char, len + 3 + len2 + 1);
 590         if (!e)
 591                 return NULL;
 592
 593         /*
 594         printf("old_length=%zu new_length=%zu x=%zu len=%u len2=%u k=%u\n",
 595                old_length, new_length, x, len, len2, k);
 596         */
 597
 598         memcpy(e, s, len);
 599         e[len + 0] = 0xe2; /* tri-dot ellipsis: … */
 600         e[len + 1] = 0x80;
 601         e[len + 2] = 0xa6;
 602
 603         memcpy(e + len + 3, j, len2 + 1);
 604
 605         return e;
 606 }
 607
 608 char *ellipsize(const char *s, size_t length, unsigned percent) {
 609
 610         if (length == (size_t) -1)
 611                 return strdup(s);
 612
 613         return ellipsize_mem(s, strlen(s), length, percent);
 614 }
 615
 616 bool nulstr_contains(const char *nulstr, const char *needle) {
 617         const char *i;
 618
 619         if (!nulstr)
 620                 return false;
 621
 622         NULSTR_FOREACH(i, nulstr)
 623                 if (streq(i, needle))
 624                         return true;
 625
 626         return false;
 627 }
 628
 629 char* strshorten(char *s, size_t l) {
 630         assert(s);
 631
 632         if (strnlen(s, l+1) > l)
 633                 s[l] = 0;
 634
 635         return s;
 636 }
 637
 638 char *strreplace(const char *text, const char *old_string, const char *new_string) {
 639         size_t l, old_len, new_len, allocated = 0;
 640         char *t, *ret = NULL;
 641         const char *f;
 642
 643         assert(old_string);
 644         assert(new_string);
 645
 646         if (!text)
 647                 return NULL;
 648
 649         old_len = strlen(old_string);
 650         new_len = strlen(new_string);
 651
 652         l = strlen(text);
 653         if (!GREEDY_REALLOC(ret, allocated, l+1))
 654                 return NULL;
 655
 656         f = text;
 657         t = ret;
 658         while (*f) {
 659                 size_t d, nl;
 660
 661                 if (!startswith(f, old_string)) {
 662                         *(t++) = *(f++);
 663                         continue;
 664                 }
 665
 666                 d = t - ret;
 667                 nl = l - old_len + new_len;
 668
 669                 if (!GREEDY_REALLOC(ret, allocated, nl + 1))
 670                         return mfree(ret);
 671
 672                 l = nl;
 673                 t = ret + d;
 674
 675                 t = stpcpy(t, new_string);
 676                 f += old_len;
 677         }
 678
 679         *t = 0;
 680         return ret;
 681 }
 682
 683 static void advance_offsets(ssize_t diff, size_t offsets[2], size_t shift[2], size_t size) {
 684         if (!offsets)
 685                 return;
 686
 687         if ((size_t) diff < offsets[0])
 688                 shift[0] += size;
 689         if ((size_t) diff < offsets[1])
 690                 shift[1] += size;
 691 }
 692
 693 char *strip_tab_ansi(char **ibuf, size_t *_isz, size_t highlight[2]) {
 694         const char *i, *begin = NULL;
 695         enum {
 696                 STATE_OTHER,
 697                 STATE_ESCAPE,
 698                 STATE_CSI,
 699                 STATE_CSO,
 700         } state = STATE_OTHER;
 701         char *obuf = NULL;
 702         size_t osz = 0, isz, shift[2] = {};
 703         FILE *f;
 704
 705         assert(ibuf);
 706         assert(*ibuf);
 707
 708         /* This does three things:
 709          *
 710          * 1. Replaces TABs by 8 spaces
 711          * 2. Strips ANSI color sequences (a subset of CSI), i.e. ESC '[' … 'm' sequences
 712          * 3. Strips ANSI operating system sequences (CSO), i.e. ESC ']' … BEL sequences
 713          *
 714          * Everything else will be left as it is. In particular other ANSI sequences are left as they are, as are any
 715          * other special characters. Truncated ANSI sequences are left-as is too. This call is supposed to suppress the
 716          * most basic formatting noise, but nothing else.
 717          *
 718          * Why care for CSO sequences? Well, to undo what terminal_urlify() and friends generate. */
 719
 720         isz = _isz ? *_isz : strlen(*ibuf);
 721
 722         f = open_memstream(&obuf, &osz);
 723         if (!f)
 724                 return NULL;
 725
 726         /* Note we turn off internal locking on f for performance reasons.  It's safe to do so since we created f here
 727          * and it doesn't leave our scope. */
 728
 729         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
 730
 731         for (i = *ibuf; i < *ibuf + isz + 1; i++) {
 732
 733                 switch (state) {
 734
 735                 case STATE_OTHER:
 736                         if (i >= *ibuf + isz) /* EOT */
 737                                 break;
 738                         else if (*i == '\x1B')
 739                                 state = STATE_ESCAPE;
 740                         else if (*i == '\t') {
 741                                 fputs("        ", f);
 742                                 advance_offsets(i - *ibuf, highlight, shift, 7);
 743                         } else
 744                                 fputc(*i, f);
 745
 746                         break;
 747
 748                 case STATE_ESCAPE:
 749                         if (i >= *ibuf + isz) { /* EOT */
 750                                 fputc('\x1B', f);
 751                                 advance_offsets(i - *ibuf, highlight, shift, 1);
 752                                 break;
 753                         } else if (*i == '[') { /* ANSI CSI */
 754                                 state = STATE_CSI;
 755                                 begin = i + 1;
 756                         } else if (*i == ']') { /* ANSI CSO */
 757                                 state = STATE_CSO;
 758                                 begin = i + 1;
 759                         } else {
 760                                 fputc('\x1B', f);
 761                                 fputc(*i, f);
 762                                 advance_offsets(i - *ibuf, highlight, shift, 1);
 763                                 state = STATE_OTHER;
 764                         }
 765
 766                         break;
 767
 768                 case STATE_CSI:
 769
 770                         if (i >= *ibuf + isz || /* EOT … */
 771                             !strchr("01234567890;m", *i)) { /* … or invalid chars in sequence */
 772                                 fputc('\x1B', f);
 773                                 fputc('[', f);
 774                                 advance_offsets(i - *ibuf, highlight, shift, 2);
 775                                 state = STATE_OTHER;
 776                                 i = begin-1;
 777                         } else if (*i == 'm')
 778                                 state = STATE_OTHER;
 779
 780                         break;
 781
 782                 case STATE_CSO:
 783
 784                         if (i >= *ibuf + isz || /* EOT … */
 785                             (*i != '\a' && (uint8_t) *i < 32U) || (uint8_t) *i > 126U) { /* … or invalid chars in sequence */
 786                                 fputc('\x1B', f);
 787                                 fputc(']', f);
 788                                 advance_offsets(i - *ibuf, highlight, shift, 2);
 789                                 state = STATE_OTHER;
 790                                 i = begin-1;
 791                         } else if (*i == '\a')
 792                                 state = STATE_OTHER;
 793
 794                         break;
 795                 }
 796         }
 797
 798         if (fflush_and_check(f) < 0) {
 799                 fclose(f);
 800                 return mfree(obuf);
 801         }
 802
 803         fclose(f);
 804
 805         free(*ibuf);
 806         *ibuf = obuf;
 807
 808         if (_isz)
 809                 *_isz = osz;
 810
 811         if (highlight) {
 812                 highlight[0] += shift[0];
 813                 highlight[1] += shift[1];
 814         }
 815
 816         return obuf;
 817 }
 818
 819 char *strextend_with_separator(char **x, const char *separator, ...) {
 820         bool need_separator;
 821         size_t f, l, l_separator;
 822         char *r, *p;
 823         va_list ap;
 824
 825         assert(x);
 826
 827         l = f = strlen_ptr(*x);
 828
 829         need_separator = !isempty(*x);
 830         l_separator = strlen_ptr(separator);
 831
 832         va_start(ap, separator);
 833         for (;;) {
 834                 const char *t;
 835                 size_t n;
 836
 837                 t = va_arg(ap, const char *);
 838                 if (!t)
 839                         break;
 840
 841                 n = strlen(t);
 842
 843                 if (need_separator)
 844                         n += l_separator;
 845
 846                 if (n > ((size_t) -1) - l) {
 847                         va_end(ap);
 848                         return NULL;
 849                 }
 850
 851                 l += n;
 852                 need_separator = true;
 853         }
 854         va_end(ap);
 855
 856         need_separator = !isempty(*x);
 857
 858         r = realloc(*x, l+1);
 859         if (!r)
 860                 return NULL;
 861
 862         p = r + f;
 863
 864         va_start(ap, separator);
 865         for (;;) {
 866                 const char *t;
 867
 868                 t = va_arg(ap, const char *);
 869                 if (!t)
 870                         break;
 871
 872                 if (need_separator && separator)
 873                         p = stpcpy(p, separator);
 874
 875                 p = stpcpy(p, t);
 876
 877                 need_separator = true;
 878         }
 879         va_end(ap);
 880
 881         assert(p == r + l);
 882
 883         *p = 0;
 884         *x = r;
 885
 886         return r + l;
 887 }
 888
 889 char *strrep(const char *s, unsigned n) {
 890         size_t l;
 891         char *r, *p;
 892         unsigned i;
 893
 894         assert(s);
 895
 896         l = strlen(s);
 897         p = r = malloc(l * n + 1);
 898         if (!r)
 899                 return NULL;
 900
 901         for (i = 0; i < n; i++)
 902                 p = stpcpy(p, s);
 903
 904         *p = 0;
 905         return r;
 906 }
 907
 908 int split_pair(const char *s, const char *sep, char **l, char **r) {
 909         char *x, *a, *b;
 910
 911         assert(s);
 912         assert(sep);
 913         assert(l);
 914         assert(r);
 915
 916         if (isempty(sep))
 917                 return -EINVAL;
 918
 919         x = strstr(s, sep);
 920         if (!x)
 921                 return -EINVAL;
 922
 923         a = strndup(s, x - s);
 924         if (!a)
 925                 return -ENOMEM;
 926
 927         b = strdup(x + strlen(sep));
 928         if (!b) {
 929                 free(a);
 930                 return -ENOMEM;
 931         }
 932
 933         *l = a;
 934         *r = b;
 935
 936         return 0;
 937 }
 938
 939 int free_and_strdup(char **p, const char *s) {
 940         char *t;
 941
 942         assert(p);
 943
 944         /* Replaces a string pointer with an strdup()ed new string,
 945          * possibly freeing the old one. */
 946
 947         if (streq_ptr(*p, s))
 948                 return 0;
 949
 950         if (s) {
 951                 t = strdup(s);
 952                 if (!t)
 953                         return -ENOMEM;
 954         } else
 955                 t = NULL;
 956
 957         free(*p);
 958         *p = t;
 959
 960         return 1;
 961 }
 962
 963 #if !HAVE_EXPLICIT_BZERO
 964 /*
 965  * Pointer to memset is volatile so that compiler must de-reference
 966  * the pointer and can't assume that it points to any function in
 967  * particular (such as memset, which it then might further "optimize")
 968  * This approach is inspired by openssl's crypto/mem_clr.c.
 969  */
 970 typedef void *(*memset_t)(void *,int,size_t);
 971
 972 static volatile memset_t memset_func = memset;
 973
 974 void explicit_bzero(void *p, size_t l) {
 975         memset_func(p, '\0', l);
 976 }
 977 #endif
 978
 979 char* string_erase(char *x) {
 980         if (!x)
 981                 return NULL;
 982
 983         /* A delicious drop of snake-oil! To be called on memory where
 984          * we stored passphrases or so, after we used them. */
 985         explicit_bzero(x, strlen(x));
 986         return x;
 987 }
 988
 989 char *string_free_erase(char *s) {
 990         return mfree(string_erase(s));
 991 }
 992
 993 bool string_is_safe(const char *p) {
 994         const char *t;
 995
 996         if (!p)
 997                 return false;
 998
 999         for (t = p; *t; t++) {
1000                 if (*t > 0 && *t < ' ') /* no control characters */
1001                         return false;
1002
1003                 if (strchr(QUOTES "\\\x7f", *t))
1004                         return false;
1005         }
1006
1007         return true;
1008 }