strbuf.c

   1 #include "cache.h"
   2 #include "refs.h"
   3 #include "utf8.h"
   4
   5 int starts_with(const char *str, const char *prefix)
   6 {
   7         for (; ; str++, prefix++)
   8                 if (!*prefix)
   9                         return 1;
  10                 else if (*str != *prefix)
  11                         return 0;
  12 }
  13
  14 /*
  15  * Used as the default ->buf value, so that people can always assume
  16  * buf is non NULL and ->buf is NUL terminated even for a freshly
  17  * initialized strbuf.
  18  */
  19 char strbuf_slopbuf[1];
  20
  21 void strbuf_init(struct strbuf *sb, size_t hint)
  22 {
  23         sb->alloc = sb->len = 0;
  24         sb->buf = strbuf_slopbuf;
  25         if (hint)
  26                 strbuf_grow(sb, hint);
  27 }
  28
  29 void strbuf_release(struct strbuf *sb)
  30 {
  31         if (sb->alloc) {
  32                 free(sb->buf);
  33                 strbuf_init(sb, 0);
  34         }
  35 }
  36
  37 char *strbuf_detach(struct strbuf *sb, size_t *sz)
  38 {
  39         char *res;
  40         strbuf_grow(sb, 0);
  41         res = sb->buf;
  42         if (sz)
  43                 *sz = sb->len;
  44         strbuf_init(sb, 0);
  45         return res;
  46 }
  47
  48 void strbuf_attach(struct strbuf *sb, void *buf, size_t len, size_t alloc)
  49 {
  50         strbuf_release(sb);
  51         sb->buf   = buf;
  52         sb->len   = len;
  53         sb->alloc = alloc;
  54         strbuf_grow(sb, 0);
  55         sb->buf[sb->len] = '\0';
  56 }
  57
  58 void strbuf_grow(struct strbuf *sb, size_t extra)
  59 {
  60         int new_buf = !sb->alloc;
  61         if (unsigned_add_overflows(extra, 1) ||
  62             unsigned_add_overflows(sb->len, extra + 1))
  63                 die("you want to use way too much memory");
  64         if (new_buf)
  65                 sb->buf = NULL;
  66         ALLOC_GROW(sb->buf, sb->len + extra + 1, sb->alloc);
  67         if (new_buf)
  68                 sb->buf[0] = '\0';
  69 }
  70
  71 void strbuf_trim(struct strbuf *sb)
  72 {
  73         strbuf_rtrim(sb);
  74         strbuf_ltrim(sb);
  75 }
  76 void strbuf_rtrim(struct strbuf *sb)
  77 {
  78         while (sb->len > 0 && isspace((unsigned char)sb->buf[sb->len - 1]))
  79                 sb->len--;
  80         sb->buf[sb->len] = '\0';
  81 }
  82
  83 void strbuf_ltrim(struct strbuf *sb)
  84 {
  85         char *b = sb->buf;
  86         while (sb->len > 0 && isspace(*b)) {
  87                 b++;
  88                 sb->len--;
  89         }
  90         memmove(sb->buf, b, sb->len);
  91         sb->buf[sb->len] = '\0';
  92 }
  93
  94 int strbuf_reencode(struct strbuf *sb, const char *from, const char *to)
  95 {
  96         char *out;
  97         int len;
  98
  99         if (same_encoding(from, to))
 100                 return 0;
 101
 102         out = reencode_string_len(sb->buf, sb->len, to, from, &len);
 103         if (!out)
 104                 return -1;
 105
 106         strbuf_attach(sb, out, len, len);
 107         return 0;
 108 }
 109
 110 void strbuf_tolower(struct strbuf *sb)
 111 {
 112         char *p = sb->buf, *end = sb->buf + sb->len;
 113         for (; p < end; p++)
 114                 *p = tolower(*p);
 115 }
 116
 117 struct strbuf **strbuf_split_buf(const char *str, size_t slen,
 118                                  int terminator, int max)
 119 {
 120         struct strbuf **ret = NULL;
 121         size_t nr = 0, alloc = 0;
 122         struct strbuf *t;
 123
 124         while (slen) {
 125                 int len = slen;
 126                 if (max <= 0 || nr + 1 < max) {
 127                         const char *end = memchr(str, terminator, slen);
 128                         if (end)
 129                                 len = end - str + 1;
 130                 }
 131                 t = xmalloc(sizeof(struct strbuf));
 132                 strbuf_init(t, len);
 133                 strbuf_add(t, str, len);
 134                 ALLOC_GROW(ret, nr + 2, alloc);
 135                 ret[nr++] = t;
 136                 str += len;
 137                 slen -= len;
 138         }
 139         ALLOC_GROW(ret, nr + 1, alloc); /* In case string was empty */
 140         ret[nr] = NULL;
 141         return ret;
 142 }
 143
 144 void strbuf_list_free(struct strbuf **sbs)
 145 {
 146         struct strbuf **s = sbs;
 147
 148         while (*s) {
 149                 strbuf_release(*s);
 150                 free(*s++);
 151         }
 152         free(sbs);
 153 }
 154
 155 int strbuf_cmp(const struct strbuf *a, const struct strbuf *b)
 156 {
 157         int len = a->len < b->len ? a->len: b->len;
 158         int cmp = memcmp(a->buf, b->buf, len);
 159         if (cmp)
 160                 return cmp;
 161         return a->len < b->len ? -1: a->len != b->len;
 162 }
 163
 164 void strbuf_splice(struct strbuf *sb, size_t pos, size_t len,
 165                                    const void *data, size_t dlen)
 166 {
 167         if (unsigned_add_overflows(pos, len))
 168                 die("you want to use way too much memory");
 169         if (pos > sb->len)
 170                 die("`pos' is too far after the end of the buffer");
 171         if (pos + len > sb->len)
 172                 die("`pos + len' is too far after the end of the buffer");
 173
 174         if (dlen >= len)
 175                 strbuf_grow(sb, dlen - len);
 176         memmove(sb->buf + pos + dlen,
 177                         sb->buf + pos + len,
 178                         sb->len - pos - len);
 179         memcpy(sb->buf + pos, data, dlen);
 180         strbuf_setlen(sb, sb->len + dlen - len);
 181 }
 182
 183 void strbuf_insert(struct strbuf *sb, size_t pos, const void *data, size_t len)
 184 {
 185         strbuf_splice(sb, pos, 0, data, len);
 186 }
 187
 188 void strbuf_remove(struct strbuf *sb, size_t pos, size_t len)
 189 {
 190         strbuf_splice(sb, pos, len, NULL, 0);
 191 }
 192
 193 void strbuf_add(struct strbuf *sb, const void *data, size_t len)
 194 {
 195         strbuf_grow(sb, len);
 196         memcpy(sb->buf + sb->len, data, len);
 197         strbuf_setlen(sb, sb->len + len);
 198 }
 199
 200 void strbuf_addbuf(struct strbuf *sb, const struct strbuf *sb2)
 201 {
 202         strbuf_grow(sb, sb2->len);
 203         memcpy(sb->buf + sb->len, sb2->buf, sb2->len);
 204         strbuf_setlen(sb, sb->len + sb2->len);
 205 }
 206
 207 void strbuf_adddup(struct strbuf *sb, size_t pos, size_t len)
 208 {
 209         strbuf_grow(sb, len);
 210         memcpy(sb->buf + sb->len, sb->buf + pos, len);
 211         strbuf_setlen(sb, sb->len + len);
 212 }
 213
 214 void strbuf_addchars(struct strbuf *sb, int c, size_t n)
 215 {
 216         strbuf_grow(sb, n);
 217         memset(sb->buf + sb->len, c, n);
 218         strbuf_setlen(sb, sb->len + n);
 219 }
 220
 221 void strbuf_addf(struct strbuf *sb, const char *fmt, ...)
 222 {
 223         va_list ap;
 224         va_start(ap, fmt);
 225         strbuf_vaddf(sb, fmt, ap);
 226         va_end(ap);
 227 }
 228
 229 static void add_lines(struct strbuf *out,
 230                         const char *prefix1,
 231                         const char *prefix2,
 232                         const char *buf, size_t size)
 233 {
 234         while (size) {
 235                 const char *prefix;
 236                 const char *next = memchr(buf, '\n', size);
 237                 next = next ? (next + 1) : (buf + size);
 238
 239                 prefix = ((prefix2 && (buf[0] == '\n' || buf[0] == '\t'))
 240                           ? prefix2 : prefix1);
 241                 strbuf_addstr(out, prefix);
 242                 strbuf_add(out, buf, next - buf);
 243                 size -= next - buf;
 244                 buf = next;
 245         }
 246         strbuf_complete_line(out);
 247 }
 248
 249 void strbuf_add_commented_lines(struct strbuf *out, const char *buf, size_t size)
 250 {
 251         static char prefix1[3];
 252         static char prefix2[2];
 253
 254         if (prefix1[0] != comment_line_char) {
 255                 sprintf(prefix1, "%c ", comment_line_char);
 256                 sprintf(prefix2, "%c", comment_line_char);
 257         }
 258         add_lines(out, prefix1, prefix2, buf, size);
 259 }
 260
 261 void strbuf_commented_addf(struct strbuf *sb, const char *fmt, ...)
 262 {
 263         va_list params;
 264         struct strbuf buf = STRBUF_INIT;
 265         int incomplete_line = sb->len && sb->buf[sb->len - 1] != '\n';
 266
 267         va_start(params, fmt);
 268         strbuf_vaddf(&buf, fmt, params);
 269         va_end(params);
 270
 271         strbuf_add_commented_lines(sb, buf.buf, buf.len);
 272         if (incomplete_line)
 273                 sb->buf[--sb->len] = '\0';
 274
 275         strbuf_release(&buf);
 276 }
 277
 278 void strbuf_vaddf(struct strbuf *sb, const char *fmt, va_list ap)
 279 {
 280         int len;
 281         va_list cp;
 282
 283         if (!strbuf_avail(sb))
 284                 strbuf_grow(sb, 64);
 285         va_copy(cp, ap);
 286         len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, cp);
 287         va_end(cp);
 288         if (len < 0)
 289                 die("BUG: your vsnprintf is broken (returned %d)", len);
 290         if (len > strbuf_avail(sb)) {
 291                 strbuf_grow(sb, len);
 292                 len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
 293                 if (len > strbuf_avail(sb))
 294                         die("BUG: your vsnprintf is broken (insatiable)");
 295         }
 296         strbuf_setlen(sb, sb->len + len);
 297 }
 298
 299 void strbuf_expand(struct strbuf *sb, const char *format, expand_fn_t fn,
 300                    void *context)
 301 {
 302         for (;;) {
 303                 const char *percent;
 304                 size_t consumed;
 305
 306                 percent = strchrnul(format, '%');
 307                 strbuf_add(sb, format, percent - format);
 308                 if (!*percent)
 309                         break;
 310                 format = percent + 1;
 311
 312                 if (*format == '%') {
 313                         strbuf_addch(sb, '%');
 314                         format++;
 315                         continue;
 316                 }
 317
 318                 consumed = fn(sb, format, context);
 319                 if (consumed)
 320                         format += consumed;
 321                 else
 322                         strbuf_addch(sb, '%');
 323         }
 324 }
 325
 326 size_t strbuf_expand_dict_cb(struct strbuf *sb, const char *placeholder,
 327                 void *context)
 328 {
 329         struct strbuf_expand_dict_entry *e = context;
 330         size_t len;
 331
 332         for (; e->placeholder && (len = strlen(e->placeholder)); e++) {
 333                 if (!strncmp(placeholder, e->placeholder, len)) {
 334                         if (e->value)
 335                                 strbuf_addstr(sb, e->value);
 336                         return len;
 337                 }
 338         }
 339         return 0;
 340 }
 341
 342 void strbuf_addbuf_percentquote(struct strbuf *dst, const struct strbuf *src)
 343 {
 344         int i, len = src->len;
 345
 346         for (i = 0; i < len; i++) {
 347                 if (src->buf[i] == '%')
 348                         strbuf_addch(dst, '%');
 349                 strbuf_addch(dst, src->buf[i]);
 350         }
 351 }
 352
 353 size_t strbuf_fread(struct strbuf *sb, size_t size, FILE *f)
 354 {
 355         size_t res;
 356         size_t oldalloc = sb->alloc;
 357
 358         strbuf_grow(sb, size);
 359         res = fread(sb->buf + sb->len, 1, size, f);
 360         if (res > 0)
 361                 strbuf_setlen(sb, sb->len + res);
 362         else if (oldalloc == 0)
 363                 strbuf_release(sb);
 364         return res;
 365 }
 366
 367 ssize_t strbuf_read(struct strbuf *sb, int fd, size_t hint)
 368 {
 369         size_t oldlen = sb->len;
 370         size_t oldalloc = sb->alloc;
 371
 372         strbuf_grow(sb, hint ? hint : 8192);
 373         for (;;) {
 374                 ssize_t want = sb->alloc - sb->len - 1;
 375                 ssize_t got = read_in_full(fd, sb->buf + sb->len, want);
 376
 377                 if (got < 0) {
 378                         if (oldalloc == 0)
 379                                 strbuf_release(sb);
 380                         else
 381                                 strbuf_setlen(sb, oldlen);
 382                         return -1;
 383                 }
 384                 sb->len += got;
 385                 if (got < want)
 386                         break;
 387                 strbuf_grow(sb, 8192);
 388         }
 389
 390         sb->buf[sb->len] = '\0';
 391         return sb->len - oldlen;
 392 }
 393
 394 #define STRBUF_MAXLINK (2*PATH_MAX)
 395
 396 int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint)
 397 {
 398         size_t oldalloc = sb->alloc;
 399
 400         if (hint < 32)
 401                 hint = 32;
 402
 403         while (hint < STRBUF_MAXLINK) {
 404                 int len;
 405
 406                 strbuf_grow(sb, hint);
 407                 len = readlink(path, sb->buf, hint);
 408                 if (len < 0) {
 409                         if (errno != ERANGE)
 410                                 break;
 411                 } else if (len < hint) {
 412                         strbuf_setlen(sb, len);
 413                         return 0;
 414                 }
 415
 416                 /* .. the buffer was too small - try again */
 417                 hint *= 2;
 418         }
 419         if (oldalloc == 0)
 420                 strbuf_release(sb);
 421         return -1;
 422 }
 423
 424 int strbuf_getcwd(struct strbuf *sb)
 425 {
 426         size_t oldalloc = sb->alloc;
 427         size_t guessed_len = 128;
 428
 429         for (;; guessed_len *= 2) {
 430                 strbuf_grow(sb, guessed_len);
 431                 if (getcwd(sb->buf, sb->alloc)) {
 432                         strbuf_setlen(sb, strlen(sb->buf));
 433                         return 0;
 434                 }
 435                 if (errno != ERANGE)
 436                         break;
 437         }
 438         if (oldalloc == 0)
 439                 strbuf_release(sb);
 440         else
 441                 strbuf_reset(sb);
 442         return -1;
 443 }
 444
 445 #ifdef HAVE_GETDELIM
 446 int strbuf_getwholeline(struct strbuf *sb, FILE *fp, int term)
 447 {
 448         ssize_t r;
 449
 450         if (feof(fp))
 451                 return EOF;
 452
 453         strbuf_reset(sb);
 454
 455         /* Translate slopbuf to NULL, as we cannot call realloc on it */
 456         if (!sb->alloc)
 457                 sb->buf = NULL;
 458         r = getdelim(&sb->buf, &sb->alloc, term, fp);
 459
 460         if (r > 0) {
 461                 sb->len = r;
 462                 return 0;
 463         }
 464         assert(r == -1);
 465
 466         /*
 467          * Normally we would have called xrealloc, which will try to free
 468          * memory and recover. But we have no way to tell getdelim() to do so.
 469          * Worse, we cannot try to recover ENOMEM ourselves, because we have
 470          * no idea how many bytes were read by getdelim.
 471          *
 472          * Dying here is reasonable. It mirrors what xrealloc would do on
 473          * catastrophic memory failure. We skip the opportunity to free pack
 474          * memory and retry, but that's unlikely to help for a malloc small
 475          * enough to hold a single line of input, anyway.
 476          */
 477         if (errno == ENOMEM)
 478                 die("Out of memory, getdelim failed");
 479
 480         /* Restore slopbuf that we moved out of the way before */
 481         if (!sb->buf)
 482                 strbuf_init(sb, 0);
 483         return EOF;
 484 }
 485 #else
 486 int strbuf_getwholeline(struct strbuf *sb, FILE *fp, int term)
 487 {
 488         int ch;
 489
 490         if (feof(fp))
 491                 return EOF;
 492
 493         strbuf_reset(sb);
 494         flockfile(fp);
 495         while ((ch = getc_unlocked(fp)) != EOF) {
 496                 if (!strbuf_avail(sb))
 497                         strbuf_grow(sb, 1);
 498                 sb->buf[sb->len++] = ch;
 499                 if (ch == term)
 500                         break;
 501         }
 502         funlockfile(fp);
 503         if (ch == EOF && sb->len == 0)
 504                 return EOF;
 505
 506         sb->buf[sb->len] = '\0';
 507         return 0;
 508 }
 509 #endif
 510
 511 int strbuf_getline(struct strbuf *sb, FILE *fp, int term)
 512 {
 513         if (strbuf_getwholeline(sb, fp, term))
 514                 return EOF;
 515         if (sb->buf[sb->len-1] == term)
 516                 strbuf_setlen(sb, sb->len-1);
 517         return 0;
 518 }
 519
 520 int strbuf_getwholeline_fd(struct strbuf *sb, int fd, int term)
 521 {
 522         strbuf_reset(sb);
 523
 524         while (1) {
 525                 char ch;
 526                 ssize_t len = xread(fd, &ch, 1);
 527                 if (len <= 0)
 528                         return EOF;
 529                 strbuf_addch(sb, ch);
 530                 if (ch == term)
 531                         break;
 532         }
 533         return 0;
 534 }
 535
 536 ssize_t strbuf_read_file(struct strbuf *sb, const char *path, size_t hint)
 537 {
 538         int fd;
 539         ssize_t len;
 540
 541         fd = open(path, O_RDONLY);
 542         if (fd < 0)
 543                 return -1;
 544         len = strbuf_read(sb, fd, hint);
 545         close(fd);
 546         if (len < 0)
 547                 return -1;
 548
 549         return len;
 550 }
 551
 552 void strbuf_add_lines(struct strbuf *out, const char *prefix,
 553                       const char *buf, size_t size)
 554 {
 555         add_lines(out, prefix, NULL, buf, size);
 556 }
 557
 558 void strbuf_addstr_xml_quoted(struct strbuf *buf, const char *s)
 559 {
 560         while (*s) {
 561                 size_t len = strcspn(s, "\"<>&");
 562                 strbuf_add(buf, s, len);
 563                 s += len;
 564                 switch (*s) {
 565                 case '"':
 566                         strbuf_addstr(buf, "&quot;");
 567                         break;
 568                 case '<':
 569                         strbuf_addstr(buf, "&lt;");
 570                         break;
 571                 case '>':
 572                         strbuf_addstr(buf, "&gt;");
 573                         break;
 574                 case '&':
 575                         strbuf_addstr(buf, "&amp;");
 576                         break;
 577                 case 0:
 578                         return;
 579                 }
 580                 s++;
 581         }
 582 }
 583
 584 static int is_rfc3986_reserved(char ch)
 585 {
 586         switch (ch) {
 587                 case '!': case '*': case '\'': case '(': case ')': case ';':
 588                 case ':': case '@': case '&': case '=': case '+': case '$':
 589                 case ',': case '/': case '?': case '#': case '[': case ']':
 590                         return 1;
 591         }
 592         return 0;
 593 }
 594
 595 static int is_rfc3986_unreserved(char ch)
 596 {
 597         return isalnum(ch) ||
 598                 ch == '-' || ch == '_' || ch == '.' || ch == '~';
 599 }
 600
 601 static void strbuf_add_urlencode(struct strbuf *sb, const char *s, size_t len,
 602                                  int reserved)
 603 {
 604         strbuf_grow(sb, len);
 605         while (len--) {
 606                 char ch = *s++;
 607                 if (is_rfc3986_unreserved(ch) ||
 608                     (!reserved && is_rfc3986_reserved(ch)))
 609                         strbuf_addch(sb, ch);
 610                 else
 611                         strbuf_addf(sb, "%%%02x", ch);
 612         }
 613 }
 614
 615 void strbuf_addstr_urlencode(struct strbuf *sb, const char *s,
 616                              int reserved)
 617 {
 618         strbuf_add_urlencode(sb, s, strlen(s), reserved);
 619 }
 620
 621 void strbuf_humanise_bytes(struct strbuf *buf, off_t bytes)
 622 {
 623         if (bytes > 1 << 30) {
 624                 strbuf_addf(buf, "%u.%2.2u GiB",
 625                             (int)(bytes >> 30),
 626                             (int)(bytes & ((1 << 30) - 1)) / 10737419);
 627         } else if (bytes > 1 << 20) {
 628                 int x = bytes + 5243;  /* for rounding */
 629                 strbuf_addf(buf, "%u.%2.2u MiB",
 630                             x >> 20, ((x & ((1 << 20) - 1)) * 100) >> 20);
 631         } else if (bytes > 1 << 10) {
 632                 int x = bytes + 5;  /* for rounding */
 633                 strbuf_addf(buf, "%u.%2.2u KiB",
 634                             x >> 10, ((x & ((1 << 10) - 1)) * 100) >> 10);
 635         } else {
 636                 strbuf_addf(buf, "%u bytes", (int)bytes);
 637         }
 638 }
 639
 640 void strbuf_add_absolute_path(struct strbuf *sb, const char *path)
 641 {
 642         if (!*path)
 643                 die("The empty string is not a valid path");
 644         if (!is_absolute_path(path)) {
 645                 struct stat cwd_stat, pwd_stat;
 646                 size_t orig_len = sb->len;
 647                 char *cwd = xgetcwd();
 648                 char *pwd = getenv("PWD");
 649                 if (pwd && strcmp(pwd, cwd) &&
 650                     !stat(cwd, &cwd_stat) &&
 651                     (cwd_stat.st_dev || cwd_stat.st_ino) &&
 652                     !stat(pwd, &pwd_stat) &&
 653                     pwd_stat.st_dev == cwd_stat.st_dev &&
 654                     pwd_stat.st_ino == cwd_stat.st_ino)
 655                         strbuf_addstr(sb, pwd);
 656                 else
 657                         strbuf_addstr(sb, cwd);
 658                 if (sb->len > orig_len && !is_dir_sep(sb->buf[sb->len - 1]))
 659                         strbuf_addch(sb, '/');
 660                 free(cwd);
 661         }
 662         strbuf_addstr(sb, path);
 663 }
 664
 665 int printf_ln(const char *fmt, ...)
 666 {
 667         int ret;
 668         va_list ap;
 669         va_start(ap, fmt);
 670         ret = vprintf(fmt, ap);
 671         va_end(ap);
 672         if (ret < 0 || putchar('\n') == EOF)
 673                 return -1;
 674         return ret + 1;
 675 }
 676
 677 int fprintf_ln(FILE *fp, const char *fmt, ...)
 678 {
 679         int ret;
 680         va_list ap;
 681         va_start(ap, fmt);
 682         ret = vfprintf(fp, fmt, ap);
 683         va_end(ap);
 684         if (ret < 0 || putc('\n', fp) == EOF)
 685                 return -1;
 686         return ret + 1;
 687 }
 688
 689 char *xstrdup_tolower(const char *string)
 690 {
 691         char *result;
 692         size_t len, i;
 693
 694         len = strlen(string);
 695         result = xmalloc(len + 1);
 696         for (i = 0; i < len; i++)
 697                 result[i] = tolower(string[i]);
 698         result[i] = '\0';
 699         return result;
 700 }
 701
 702 char *xstrvfmt(const char *fmt, va_list ap)
 703 {
 704         struct strbuf buf = STRBUF_INIT;
 705         strbuf_vaddf(&buf, fmt, ap);
 706         return strbuf_detach(&buf, NULL);
 707 }
 708
 709 char *xstrfmt(const char *fmt, ...)
 710 {
 711         va_list ap;
 712         char *ret;
 713
 714         va_start(ap, fmt);
 715         ret = xstrvfmt(fmt, ap);
 716         va_end(ap);
 717
 718         return ret;
 719 }
 720
 721 void strbuf_addftime(struct strbuf *sb, const char *fmt, const struct tm *tm)
 722 {
 723         size_t hint = 128;
 724         size_t len;
 725
 726         if (!*fmt)
 727                 return;
 728
 729         strbuf_grow(sb, hint);
 730         len = strftime(sb->buf + sb->len, sb->alloc - sb->len, fmt, tm);
 731
 732         if (!len) {
 733                 /*
 734                  * strftime reports "0" if it could not fit the result in the buffer.
 735                  * Unfortunately, it also reports "0" if the requested time string
 736                  * takes 0 bytes. So our strategy is to munge the format so that the
 737                  * output contains at least one character, and then drop the extra
 738                  * character before returning.
 739                  */
 740                 struct strbuf munged_fmt = STRBUF_INIT;
 741                 strbuf_addf(&munged_fmt, "%s ", fmt);
 742                 while (!len) {
 743                         hint *= 2;
 744                         strbuf_grow(sb, hint);
 745                         len = strftime(sb->buf + sb->len, sb->alloc - sb->len,
 746                                        munged_fmt.buf, tm);
 747                 }
 748                 strbuf_release(&munged_fmt);
 749                 len--; /* drop munged space */
 750         }
 751         strbuf_setlen(sb, sb->len + len);
 752 }
 753
 754 /*
 755  * Returns the length of a line, without trailing spaces.
 756  *
 757  * If the line ends with newline, it will be removed too.
 758  */
 759 static size_t cleanup(char *line, size_t len)
 760 {
 761         while (len) {
 762                 unsigned char c = line[len - 1];
 763                 if (!isspace(c))
 764                         break;
 765                 len--;
 766         }
 767
 768         return len;
 769 }
 770
 771 /*
 772  * Remove empty lines from the beginning and end
 773  * and also trailing spaces from every line.
 774  *
 775  * Turn multiple consecutive empty lines between paragraphs
 776  * into just one empty line.
 777  *
 778  * If the input has only empty lines and spaces,
 779  * no output will be produced.
 780  *
 781  * If last line does not have a newline at the end, one is added.
 782  *
 783  * Enable skip_comments to skip every line starting with comment
 784  * character.
 785  */
 786 void strbuf_stripspace(struct strbuf *sb, int skip_comments)
 787 {
 788         int empties = 0;
 789         size_t i, j, len, newlen;
 790         char *eol;
 791
 792         /* We may have to add a newline. */
 793         strbuf_grow(sb, 1);
 794
 795         for (i = j = 0; i < sb->len; i += len, j += newlen) {
 796                 eol = memchr(sb->buf + i, '\n', sb->len - i);
 797                 len = eol ? eol - (sb->buf + i) + 1 : sb->len - i;
 798
 799                 if (skip_comments && len && sb->buf[i] == comment_line_char) {
 800                         newlen = 0;
 801                         continue;
 802                 }
 803                 newlen = cleanup(sb->buf + i, len);
 804
 805                 /* Not just an empty line? */
 806                 if (newlen) {
 807                         if (empties > 0 && j > 0)
 808                                 sb->buf[j++] = '\n';
 809                         empties = 0;
 810                         memmove(sb->buf + j, sb->buf + i, newlen);
 811                         sb->buf[newlen + j++] = '\n';
 812                 } else {
 813                         empties++;
 814                 }
 815         }
 816
 817         strbuf_setlen(sb, j);
 818 }