trailer.c

   1 #include "cache.h"
   2 #include "string-list.h"
   3 #include "run-command.h"
   4 #include "string-list.h"
   5 #include "trailer.h"
   6 /*
   7  * Copyright (c) 2013, 2014 Christian Couder <chriscool@tuxfamily.org>
   8  */
   9
  10 enum action_where { WHERE_END, WHERE_AFTER, WHERE_BEFORE, WHERE_START };
  11 enum action_if_exists { EXISTS_ADD_IF_DIFFERENT_NEIGHBOR, EXISTS_ADD_IF_DIFFERENT,
  12                         EXISTS_ADD, EXISTS_REPLACE, EXISTS_DO_NOTHING };
  13 enum action_if_missing { MISSING_ADD, MISSING_DO_NOTHING };
  14
  15 struct conf_info {
  16         char *name;
  17         char *key;
  18         char *command;
  19         enum action_where where;
  20         enum action_if_exists if_exists;
  21         enum action_if_missing if_missing;
  22 };
  23
  24 static struct conf_info default_conf_info;
  25
  26 struct trailer_item {
  27         struct trailer_item *previous;
  28         struct trailer_item *next;
  29         const char *token;
  30         const char *value;
  31         struct conf_info conf;
  32 };
  33
  34 static struct trailer_item *first_conf_item;
  35
  36 static char *separators = ":";
  37
  38 #define TRAILER_ARG_STRING "$ARG"
  39
  40 static int after_or_end(enum action_where where)
  41 {
  42         return (where == WHERE_AFTER) || (where == WHERE_END);
  43 }
  44
  45 /*
  46  * Return the length of the string not including any final
  47  * punctuation. E.g., the input "Signed-off-by:" would return
  48  * 13, stripping the trailing punctuation but retaining
  49  * internal punctuation.
  50  */
  51 static size_t token_len_without_separator(const char *token, size_t len)
  52 {
  53         while (len > 0 && !isalnum(token[len - 1]))
  54                 len--;
  55         return len;
  56 }
  57
  58 static int same_token(struct trailer_item *a, struct trailer_item *b)
  59 {
  60         size_t a_len = token_len_without_separator(a->token, strlen(a->token));
  61         size_t b_len = token_len_without_separator(b->token, strlen(b->token));
  62         size_t min_len = (a_len > b_len) ? b_len : a_len;
  63
  64         return !strncasecmp(a->token, b->token, min_len);
  65 }
  66
  67 static int same_value(struct trailer_item *a, struct trailer_item *b)
  68 {
  69         return !strcasecmp(a->value, b->value);
  70 }
  71
  72 static int same_trailer(struct trailer_item *a, struct trailer_item *b)
  73 {
  74         return same_token(a, b) && same_value(a, b);
  75 }
  76
  77 static inline int contains_only_spaces(const char *str)
  78 {
  79         const char *s = str;
  80         while (*s && isspace(*s))
  81                 s++;
  82         return !*s;
  83 }
  84
  85 static inline void strbuf_replace(struct strbuf *sb, const char *a, const char *b)
  86 {
  87         const char *ptr = strstr(sb->buf, a);
  88         if (ptr)
  89                 strbuf_splice(sb, ptr - sb->buf, strlen(a), b, strlen(b));
  90 }
  91
  92 static void free_trailer_item(struct trailer_item *item)
  93 {
  94         free(item->conf.name);
  95         free(item->conf.key);
  96         free(item->conf.command);
  97         free((char *)item->token);
  98         free((char *)item->value);
  99         free(item);
 100 }
 101
 102 static char last_non_space_char(const char *s)
 103 {
 104         int i;
 105         for (i = strlen(s) - 1; i >= 0; i--)
 106                 if (!isspace(s[i]))
 107                         return s[i];
 108         return '\0';
 109 }
 110
 111 static void print_tok_val(const char *tok, const char *val)
 112 {
 113         char c = last_non_space_char(tok);
 114         if (!c)
 115                 return;
 116         if (strchr(separators, c))
 117                 printf("%s%s\n", tok, val);
 118         else
 119                 printf("%s%c %s\n", tok, separators[0], val);
 120 }
 121
 122 static void print_all(struct trailer_item *first, int trim_empty)
 123 {
 124         struct trailer_item *item;
 125         for (item = first; item; item = item->next) {
 126                 if (!trim_empty || strlen(item->value) > 0)
 127                         print_tok_val(item->token, item->value);
 128         }
 129 }
 130
 131 static void update_last(struct trailer_item **last)
 132 {
 133         if (*last)
 134                 while ((*last)->next != NULL)
 135                         *last = (*last)->next;
 136 }
 137
 138 static void update_first(struct trailer_item **first)
 139 {
 140         if (*first)
 141                 while ((*first)->previous != NULL)
 142                         *first = (*first)->previous;
 143 }
 144
 145 static void add_arg_to_input_list(struct trailer_item *on_tok,
 146                                   struct trailer_item *arg_tok,
 147                                   struct trailer_item **first,
 148                                   struct trailer_item **last)
 149 {
 150         if (after_or_end(arg_tok->conf.where)) {
 151                 arg_tok->next = on_tok->next;
 152                 on_tok->next = arg_tok;
 153                 arg_tok->previous = on_tok;
 154                 if (arg_tok->next)
 155                         arg_tok->next->previous = arg_tok;
 156                 update_last(last);
 157         } else {
 158                 arg_tok->previous = on_tok->previous;
 159                 on_tok->previous = arg_tok;
 160                 arg_tok->next = on_tok;
 161                 if (arg_tok->previous)
 162                         arg_tok->previous->next = arg_tok;
 163                 update_first(first);
 164         }
 165 }
 166
 167 static int check_if_different(struct trailer_item *in_tok,
 168                               struct trailer_item *arg_tok,
 169                               int check_all)
 170 {
 171         enum action_where where = arg_tok->conf.where;
 172         do {
 173                 if (!in_tok)
 174                         return 1;
 175                 if (same_trailer(in_tok, arg_tok))
 176                         return 0;
 177                 /*
 178                  * if we want to add a trailer after another one,
 179                  * we have to check those before this one
 180                  */
 181                 in_tok = after_or_end(where) ? in_tok->previous : in_tok->next;
 182         } while (check_all);
 183         return 1;
 184 }
 185
 186 static void remove_from_list(struct trailer_item *item,
 187                              struct trailer_item **first,
 188                              struct trailer_item **last)
 189 {
 190         struct trailer_item *next = item->next;
 191         struct trailer_item *previous = item->previous;
 192
 193         if (next) {
 194                 item->next->previous = previous;
 195                 item->next = NULL;
 196         } else if (last)
 197                 *last = previous;
 198
 199         if (previous) {
 200                 item->previous->next = next;
 201                 item->previous = NULL;
 202         } else if (first)
 203                 *first = next;
 204 }
 205
 206 static struct trailer_item *remove_first(struct trailer_item **first)
 207 {
 208         struct trailer_item *item = *first;
 209         *first = item->next;
 210         if (item->next) {
 211                 item->next->previous = NULL;
 212                 item->next = NULL;
 213         }
 214         return item;
 215 }
 216
 217 static int read_from_command(struct child_process *cp, struct strbuf *buf)
 218 {
 219         if (run_command(cp))
 220                 return error("running trailer command '%s' failed", cp->argv[0]);
 221         if (strbuf_read(buf, cp->out, 1024) < 1)
 222                 return error("reading from trailer command '%s' failed", cp->argv[0]);
 223         strbuf_trim(buf);
 224         return 0;
 225 }
 226
 227 static const char *apply_command(const char *command, const char *arg)
 228 {
 229         struct strbuf cmd = STRBUF_INIT;
 230         struct strbuf buf = STRBUF_INIT;
 231         struct child_process cp;
 232         const char *argv[] = {NULL, NULL};
 233         const char *result;
 234
 235         strbuf_addstr(&cmd, command);
 236         if (arg)
 237                 strbuf_replace(&cmd, TRAILER_ARG_STRING, arg);
 238
 239         argv[0] = cmd.buf;
 240         child_process_init(&cp);
 241         cp.argv = argv;
 242         cp.env = local_repo_env;
 243         cp.no_stdin = 1;
 244         cp.out = -1;
 245         cp.use_shell = 1;
 246
 247         if (read_from_command(&cp, &buf)) {
 248                 strbuf_release(&buf);
 249                 result = xstrdup("");
 250         } else
 251                 result = strbuf_detach(&buf, NULL);
 252
 253         strbuf_release(&cmd);
 254         return result;
 255 }
 256
 257 static void apply_item_command(struct trailer_item *in_tok, struct trailer_item *arg_tok)
 258 {
 259         if (arg_tok->conf.command) {
 260                 const char *arg;
 261                 if (arg_tok->value && arg_tok->value[0]) {
 262                         arg = arg_tok->value;
 263                 } else {
 264                         if (in_tok && in_tok->value)
 265                                 arg = xstrdup(in_tok->value);
 266                         else
 267                                 arg = xstrdup("");
 268                 }
 269                 arg_tok->value = apply_command(arg_tok->conf.command, arg);
 270                 free((char *)arg);
 271         }
 272 }
 273
 274 static void apply_arg_if_exists(struct trailer_item *in_tok,
 275                                 struct trailer_item *arg_tok,
 276                                 struct trailer_item *on_tok,
 277                                 struct trailer_item **in_tok_first,
 278                                 struct trailer_item **in_tok_last)
 279 {
 280         switch (arg_tok->conf.if_exists) {
 281         case EXISTS_DO_NOTHING:
 282                 free_trailer_item(arg_tok);
 283                 break;
 284         case EXISTS_REPLACE:
 285                 apply_item_command(in_tok, arg_tok);
 286                 add_arg_to_input_list(on_tok, arg_tok,
 287                                       in_tok_first, in_tok_last);
 288                 remove_from_list(in_tok, in_tok_first, in_tok_last);
 289                 free_trailer_item(in_tok);
 290                 break;
 291         case EXISTS_ADD:
 292                 apply_item_command(in_tok, arg_tok);
 293                 add_arg_to_input_list(on_tok, arg_tok,
 294                                       in_tok_first, in_tok_last);
 295                 break;
 296         case EXISTS_ADD_IF_DIFFERENT:
 297                 apply_item_command(in_tok, arg_tok);
 298                 if (check_if_different(in_tok, arg_tok, 1))
 299                         add_arg_to_input_list(on_tok, arg_tok,
 300                                               in_tok_first, in_tok_last);
 301                 else
 302                         free_trailer_item(arg_tok);
 303                 break;
 304         case EXISTS_ADD_IF_DIFFERENT_NEIGHBOR:
 305                 apply_item_command(in_tok, arg_tok);
 306                 if (check_if_different(on_tok, arg_tok, 0))
 307                         add_arg_to_input_list(on_tok, arg_tok,
 308                                               in_tok_first, in_tok_last);
 309                 else
 310                         free_trailer_item(arg_tok);
 311                 break;
 312         }
 313 }
 314
 315 static void apply_arg_if_missing(struct trailer_item **in_tok_first,
 316                                  struct trailer_item **in_tok_last,
 317                                  struct trailer_item *arg_tok)
 318 {
 319         struct trailer_item **in_tok;
 320         enum action_where where;
 321
 322         switch (arg_tok->conf.if_missing) {
 323         case MISSING_DO_NOTHING:
 324                 free_trailer_item(arg_tok);
 325                 break;
 326         case MISSING_ADD:
 327                 where = arg_tok->conf.where;
 328                 in_tok = after_or_end(where) ? in_tok_last : in_tok_first;
 329                 apply_item_command(NULL, arg_tok);
 330                 if (*in_tok) {
 331                         add_arg_to_input_list(*in_tok, arg_tok,
 332                                               in_tok_first, in_tok_last);
 333                 } else {
 334                         *in_tok_first = arg_tok;
 335                         *in_tok_last = arg_tok;
 336                 }
 337                 break;
 338         }
 339 }
 340
 341 static int find_same_and_apply_arg(struct trailer_item **in_tok_first,
 342                                    struct trailer_item **in_tok_last,
 343                                    struct trailer_item *arg_tok)
 344 {
 345         struct trailer_item *in_tok;
 346         struct trailer_item *on_tok;
 347         struct trailer_item *following_tok;
 348
 349         enum action_where where = arg_tok->conf.where;
 350         int middle = (where == WHERE_AFTER) || (where == WHERE_BEFORE);
 351         int backwards = after_or_end(where);
 352         struct trailer_item *start_tok = backwards ? *in_tok_last : *in_tok_first;
 353
 354         for (in_tok = start_tok; in_tok; in_tok = following_tok) {
 355                 following_tok = backwards ? in_tok->previous : in_tok->next;
 356                 if (!same_token(in_tok, arg_tok))
 357                         continue;
 358                 on_tok = middle ? in_tok : start_tok;
 359                 apply_arg_if_exists(in_tok, arg_tok, on_tok,
 360                                     in_tok_first, in_tok_last);
 361                 return 1;
 362         }
 363         return 0;
 364 }
 365
 366 static void process_trailers_lists(struct trailer_item **in_tok_first,
 367                                    struct trailer_item **in_tok_last,
 368                                    struct trailer_item **arg_tok_first)
 369 {
 370         struct trailer_item *arg_tok;
 371         struct trailer_item *next_arg;
 372
 373         if (!*arg_tok_first)
 374                 return;
 375
 376         for (arg_tok = *arg_tok_first; arg_tok; arg_tok = next_arg) {
 377                 int applied = 0;
 378
 379                 next_arg = arg_tok->next;
 380                 remove_from_list(arg_tok, arg_tok_first, NULL);
 381
 382                 applied = find_same_and_apply_arg(in_tok_first,
 383                                                   in_tok_last,
 384                                                   arg_tok);
 385
 386                 if (!applied)
 387                         apply_arg_if_missing(in_tok_first,
 388                                              in_tok_last,
 389                                              arg_tok);
 390         }
 391 }
 392
 393 static int set_where(struct conf_info *item, const char *value)
 394 {
 395         if (!strcasecmp("after", value))
 396                 item->where = WHERE_AFTER;
 397         else if (!strcasecmp("before", value))
 398                 item->where = WHERE_BEFORE;
 399         else if (!strcasecmp("end", value))
 400                 item->where = WHERE_END;
 401         else if (!strcasecmp("start", value))
 402                 item->where = WHERE_START;
 403         else
 404                 return -1;
 405         return 0;
 406 }
 407
 408 static int set_if_exists(struct conf_info *item, const char *value)
 409 {
 410         if (!strcasecmp("addIfDifferent", value))
 411                 item->if_exists = EXISTS_ADD_IF_DIFFERENT;
 412         else if (!strcasecmp("addIfDifferentNeighbor", value))
 413                 item->if_exists = EXISTS_ADD_IF_DIFFERENT_NEIGHBOR;
 414         else if (!strcasecmp("add", value))
 415                 item->if_exists = EXISTS_ADD;
 416         else if (!strcasecmp("replace", value))
 417                 item->if_exists = EXISTS_REPLACE;
 418         else if (!strcasecmp("doNothing", value))
 419                 item->if_exists = EXISTS_DO_NOTHING;
 420         else
 421                 return -1;
 422         return 0;
 423 }
 424
 425 static int set_if_missing(struct conf_info *item, const char *value)
 426 {
 427         if (!strcasecmp("doNothing", value))
 428                 item->if_missing = MISSING_DO_NOTHING;
 429         else if (!strcasecmp("add", value))
 430                 item->if_missing = MISSING_ADD;
 431         else
 432                 return -1;
 433         return 0;
 434 }
 435
 436 static void duplicate_conf(struct conf_info *dst, struct conf_info *src)
 437 {
 438         *dst = *src;
 439         if (src->name)
 440                 dst->name = xstrdup(src->name);
 441         if (src->key)
 442                 dst->key = xstrdup(src->key);
 443         if (src->command)
 444                 dst->command = xstrdup(src->command);
 445 }
 446
 447 static struct trailer_item *get_conf_item(const char *name)
 448 {
 449         struct trailer_item *item;
 450         struct trailer_item *previous;
 451
 452         /* Look up item with same name */
 453         for (previous = NULL, item = first_conf_item;
 454              item;
 455              previous = item, item = item->next) {
 456                 if (!strcasecmp(item->conf.name, name))
 457                         return item;
 458         }
 459
 460         /* Item does not already exists, create it */
 461         item = xcalloc(sizeof(struct trailer_item), 1);
 462         duplicate_conf(&item->conf, &default_conf_info);
 463         item->conf.name = xstrdup(name);
 464
 465         if (!previous)
 466                 first_conf_item = item;
 467         else {
 468                 previous->next = item;
 469                 item->previous = previous;
 470         }
 471
 472         return item;
 473 }
 474
 475 enum trailer_info_type { TRAILER_KEY, TRAILER_COMMAND, TRAILER_WHERE,
 476                          TRAILER_IF_EXISTS, TRAILER_IF_MISSING };
 477
 478 static struct {
 479         const char *name;
 480         enum trailer_info_type type;
 481 } trailer_config_items[] = {
 482         { "key", TRAILER_KEY },
 483         { "command", TRAILER_COMMAND },
 484         { "where", TRAILER_WHERE },
 485         { "ifexists", TRAILER_IF_EXISTS },
 486         { "ifmissing", TRAILER_IF_MISSING }
 487 };
 488
 489 static int git_trailer_default_config(const char *conf_key, const char *value, void *cb)
 490 {
 491         const char *trailer_item, *variable_name;
 492
 493         if (!skip_prefix(conf_key, "trailer.", &trailer_item))
 494                 return 0;
 495
 496         variable_name = strrchr(trailer_item, '.');
 497         if (!variable_name) {
 498                 if (!strcmp(trailer_item, "where")) {
 499                         if (set_where(&default_conf_info, value) < 0)
 500                                 warning(_("unknown value '%s' for key '%s'"),
 501                                         value, conf_key);
 502                 } else if (!strcmp(trailer_item, "ifexists")) {
 503                         if (set_if_exists(&default_conf_info, value) < 0)
 504                                 warning(_("unknown value '%s' for key '%s'"),
 505                                         value, conf_key);
 506                 } else if (!strcmp(trailer_item, "ifmissing")) {
 507                         if (set_if_missing(&default_conf_info, value) < 0)
 508                                 warning(_("unknown value '%s' for key '%s'"),
 509                                         value, conf_key);
 510                 } else if (!strcmp(trailer_item, "separators")) {
 511                         separators = xstrdup(value);
 512                 }
 513         }
 514         return 0;
 515 }
 516
 517 static int git_trailer_config(const char *conf_key, const char *value, void *cb)
 518 {
 519         const char *trailer_item, *variable_name;
 520         struct trailer_item *item;
 521         struct conf_info *conf;
 522         char *name = NULL;
 523         enum trailer_info_type type;
 524         int i;
 525
 526         if (!skip_prefix(conf_key, "trailer.", &trailer_item))
 527                 return 0;
 528
 529         variable_name = strrchr(trailer_item, '.');
 530         if (!variable_name)
 531                 return 0;
 532
 533         variable_name++;
 534         for (i = 0; i < ARRAY_SIZE(trailer_config_items); i++) {
 535                 if (strcmp(trailer_config_items[i].name, variable_name))
 536                         continue;
 537                 name = xstrndup(trailer_item,  variable_name - trailer_item - 1);
 538                 type = trailer_config_items[i].type;
 539                 break;
 540         }
 541
 542         if (!name)
 543                 return 0;
 544
 545         item = get_conf_item(name);
 546         conf = &item->conf;
 547         free(name);
 548
 549         switch (type) {
 550         case TRAILER_KEY:
 551                 if (conf->key)
 552                         warning(_("more than one %s"), conf_key);
 553                 conf->key = xstrdup(value);
 554                 break;
 555         case TRAILER_COMMAND:
 556                 if (conf->command)
 557                         warning(_("more than one %s"), conf_key);
 558                 conf->command = xstrdup(value);
 559                 break;
 560         case TRAILER_WHERE:
 561                 if (set_where(conf, value))
 562                         warning(_("unknown value '%s' for key '%s'"), value, conf_key);
 563                 break;
 564         case TRAILER_IF_EXISTS:
 565                 if (set_if_exists(conf, value))
 566                         warning(_("unknown value '%s' for key '%s'"), value, conf_key);
 567                 break;
 568         case TRAILER_IF_MISSING:
 569                 if (set_if_missing(conf, value))
 570                         warning(_("unknown value '%s' for key '%s'"), value, conf_key);
 571                 break;
 572         default:
 573                 die("internal bug in trailer.c");
 574         }
 575         return 0;
 576 }
 577
 578 static int parse_trailer(struct strbuf *tok, struct strbuf *val, const char *trailer)
 579 {
 580         size_t len;
 581         struct strbuf seps = STRBUF_INIT;
 582         strbuf_addstr(&seps, separators);
 583         strbuf_addch(&seps, '=');
 584         len = strcspn(trailer, seps.buf);
 585         strbuf_release(&seps);
 586         if (len == 0)
 587                 return error(_("empty trailer token in trailer '%s'"), trailer);
 588         if (len < strlen(trailer)) {
 589                 strbuf_add(tok, trailer, len);
 590                 strbuf_trim(tok);
 591                 strbuf_addstr(val, trailer + len + 1);
 592                 strbuf_trim(val);
 593         } else {
 594                 strbuf_addstr(tok, trailer);
 595                 strbuf_trim(tok);
 596         }
 597         return 0;
 598 }
 599
 600 static const char *token_from_item(struct trailer_item *item, char *tok)
 601 {
 602         if (item->conf.key)
 603                 return item->conf.key;
 604         if (tok)
 605                 return tok;
 606         return item->conf.name;
 607 }
 608
 609 static struct trailer_item *new_trailer_item(struct trailer_item *conf_item,
 610                                              char *tok, char *val)
 611 {
 612         struct trailer_item *new = xcalloc(sizeof(*new), 1);
 613         new->value = val ? val : xstrdup("");
 614
 615         if (conf_item) {
 616                 duplicate_conf(&new->conf, &conf_item->conf);
 617                 new->token = xstrdup(token_from_item(conf_item, tok));
 618                 free(tok);
 619         } else {
 620                 duplicate_conf(&new->conf, &default_conf_info);
 621                 new->token = tok;
 622         }
 623
 624         return new;
 625 }
 626
 627 static int token_matches_item(const char *tok, struct trailer_item *item, int tok_len)
 628 {
 629         if (!strncasecmp(tok, item->conf.name, tok_len))
 630                 return 1;
 631         return item->conf.key ? !strncasecmp(tok, item->conf.key, tok_len) : 0;
 632 }
 633
 634 static struct trailer_item *create_trailer_item(const char *string)
 635 {
 636         struct strbuf tok = STRBUF_INIT;
 637         struct strbuf val = STRBUF_INIT;
 638         struct trailer_item *item;
 639         int tok_len;
 640
 641         if (parse_trailer(&tok, &val, string))
 642                 return NULL;
 643
 644         tok_len = token_len_without_separator(tok.buf, tok.len);
 645
 646         /* Lookup if the token matches something in the config */
 647         for (item = first_conf_item; item; item = item->next) {
 648                 if (token_matches_item(tok.buf, item, tok_len))
 649                         return new_trailer_item(item,
 650                                                 strbuf_detach(&tok, NULL),
 651                                                 strbuf_detach(&val, NULL));
 652         }
 653
 654         return new_trailer_item(NULL,
 655                                 strbuf_detach(&tok, NULL),
 656                                 strbuf_detach(&val, NULL));
 657 }
 658
 659 static void add_trailer_item(struct trailer_item **first,
 660                              struct trailer_item **last,
 661                              struct trailer_item *new)
 662 {
 663         if (!new)
 664                 return;
 665         if (!*last) {
 666                 *first = new;
 667                 *last = new;
 668         } else {
 669                 (*last)->next = new;
 670                 new->previous = *last;
 671                 *last = new;
 672         }
 673 }
 674
 675 static struct trailer_item *process_command_line_args(struct string_list *trailers)
 676 {
 677         struct trailer_item *arg_tok_first = NULL;
 678         struct trailer_item *arg_tok_last = NULL;
 679         struct string_list_item *tr;
 680         struct trailer_item *item;
 681
 682         /* Add a trailer item for each configured trailer with a command */
 683         for (item = first_conf_item; item; item = item->next) {
 684                 if (item->conf.command) {
 685                         struct trailer_item *new = new_trailer_item(item, NULL, NULL);
 686                         add_trailer_item(&arg_tok_first, &arg_tok_last, new);
 687                 }
 688         }
 689
 690         /* Add a trailer item for each trailer on the command line */
 691         for_each_string_list_item(tr, trailers) {
 692                 struct trailer_item *new = create_trailer_item(tr->string);
 693                 add_trailer_item(&arg_tok_first, &arg_tok_last, new);
 694         }
 695
 696         return arg_tok_first;
 697 }
 698
 699 static struct strbuf **read_input_file(const char *file)
 700 {
 701         struct strbuf **lines;
 702         struct strbuf sb = STRBUF_INIT;
 703
 704         if (file) {
 705                 if (strbuf_read_file(&sb, file, 0) < 0)
 706                         die_errno(_("could not read input file '%s'"), file);
 707         } else {
 708                 if (strbuf_read(&sb, fileno(stdin), 0) < 0)
 709                         die_errno(_("could not read from stdin"));
 710         }
 711
 712         lines = strbuf_split(&sb, '\n');
 713
 714         strbuf_release(&sb);
 715
 716         return lines;
 717 }
 718
 719 /*
 720  * Return the (0 based) index of the start of the patch or the line
 721  * count if there is no patch in the message.
 722  */
 723 static int find_patch_start(struct strbuf **lines, int count)
 724 {
 725         int i;
 726
 727         /* Get the start of the patch part if any */
 728         for (i = 0; i < count; i++) {
 729                 if (starts_with(lines[i]->buf, "---"))
 730                         return i;
 731         }
 732
 733         return count;
 734 }
 735
 736 /*
 737  * Return the (0 based) index of the first trailer line or count if
 738  * there are no trailers. Trailers are searched only in the lines from
 739  * index (count - 1) down to index 0.
 740  */
 741 static int find_trailer_start(struct strbuf **lines, int count)
 742 {
 743         int start, only_spaces = 1;
 744
 745         /*
 746          * Get the start of the trailers by looking starting from the end
 747          * for a line with only spaces before lines with one separator.
 748          */
 749         for (start = count - 1; start >= 0; start--) {
 750                 if (lines[start]->buf[0] == comment_line_char)
 751                         continue;
 752                 if (contains_only_spaces(lines[start]->buf)) {
 753                         if (only_spaces)
 754                                 continue;
 755                         return start + 1;
 756                 }
 757                 if (strcspn(lines[start]->buf, separators) < lines[start]->len) {
 758                         if (only_spaces)
 759                                 only_spaces = 0;
 760                         continue;
 761                 }
 762                 return count;
 763         }
 764
 765         return only_spaces ? count : 0;
 766 }
 767
 768 static int has_blank_line_before(struct strbuf **lines, int start)
 769 {
 770         for (;start >= 0; start--) {
 771                 if (lines[start]->buf[0] == comment_line_char)
 772                         continue;
 773                 return contains_only_spaces(lines[start]->buf);
 774         }
 775         return 0;
 776 }
 777
 778 static void print_lines(struct strbuf **lines, int start, int end)
 779 {
 780         int i;
 781         for (i = start; lines[i] && i < end; i++)
 782                 printf("%s", lines[i]->buf);
 783 }
 784
 785 static int process_input_file(struct strbuf **lines,
 786                               struct trailer_item **in_tok_first,
 787                               struct trailer_item **in_tok_last)
 788 {
 789         int count = 0;
 790         int patch_start, trailer_start, i;
 791
 792         /* Get the line count */
 793         while (lines[count])
 794                 count++;
 795
 796         patch_start = find_patch_start(lines, count);
 797         trailer_start = find_trailer_start(lines, patch_start);
 798
 799         /* Print lines before the trailers as is */
 800         print_lines(lines, 0, trailer_start);
 801
 802         if (!has_blank_line_before(lines, trailer_start - 1))
 803                 printf("\n");
 804
 805         /* Parse trailer lines */
 806         for (i = trailer_start; i < patch_start; i++) {
 807                 struct trailer_item *new = create_trailer_item(lines[i]->buf);
 808                 add_trailer_item(in_tok_first, in_tok_last, new);
 809         }
 810
 811         return patch_start;
 812 }
 813
 814 static void free_all(struct trailer_item **first)
 815 {
 816         while (*first) {
 817                 struct trailer_item *item = remove_first(first);
 818                 free_trailer_item(item);
 819         }
 820 }
 821
 822 void process_trailers(const char *file, int trim_empty, struct string_list *trailers)
 823 {
 824         struct trailer_item *in_tok_first = NULL;
 825         struct trailer_item *in_tok_last = NULL;
 826         struct trailer_item *arg_tok_first;
 827         struct strbuf **lines;
 828         int patch_start;
 829
 830         /* Default config must be setup first */
 831         git_config(git_trailer_default_config, NULL);
 832         git_config(git_trailer_config, NULL);
 833
 834         lines = read_input_file(file);
 835
 836         /* Print the lines before the trailers */
 837         patch_start = process_input_file(lines, &in_tok_first, &in_tok_last);
 838
 839         arg_tok_first = process_command_line_args(trailers);
 840
 841         process_trailers_lists(&in_tok_first, &in_tok_last, &arg_tok_first);
 842
 843         print_all(in_tok_first, trim_empty);
 844
 845         free_all(&in_tok_first);
 846
 847         /* Print the lines after the trailers as is */
 848         print_lines(lines, patch_start, INT_MAX);
 849
 850         strbuf_list_free(lines);
 851 }