trailer.c

   1 #include "cache.h"
   2 #include "string-list.h"
   3 #include "run-command.h"
   4 #include "commit.h"
   5 #include "tempfile.h"
   6 #include "trailer.h"
   7 #include "list.h"
   8 /*
   9  * Copyright (c) 2013, 2014 Christian Couder <chriscool@tuxfamily.org>
  10  */
  11
  12 enum action_where { WHERE_END, WHERE_AFTER, WHERE_BEFORE, WHERE_START };
  13 enum action_if_exists { EXISTS_ADD_IF_DIFFERENT_NEIGHBOR, EXISTS_ADD_IF_DIFFERENT,
  14                         EXISTS_ADD, EXISTS_REPLACE, EXISTS_DO_NOTHING };
  15 enum action_if_missing { MISSING_ADD, MISSING_DO_NOTHING };
  16
  17 struct conf_info {
  18         char *name;
  19         char *key;
  20         char *command;
  21         enum action_where where;
  22         enum action_if_exists if_exists;
  23         enum action_if_missing if_missing;
  24 };
  25
  26 static struct conf_info default_conf_info;
  27
  28 struct trailer_item {
  29         struct list_head list;
  30         /*
  31          * If this is not a trailer line, the line is stored in value
  32          * (excluding the terminating newline) and token is NULL.
  33          */
  34         char *token;
  35         char *value;
  36 };
  37
  38 struct arg_item {
  39         struct list_head list;
  40         char *token;
  41         char *value;
  42         struct conf_info conf;
  43 };
  44
  45 static LIST_HEAD(conf_head);
  46
  47 static char *separators = ":";
  48
  49 #define TRAILER_ARG_STRING "$ARG"
  50
  51 static const char *git_generated_prefixes[] = {
  52         "Signed-off-by: ",
  53         "(cherry picked from commit ",
  54         NULL
  55 };
  56
  57 /* Iterate over the elements of the list. */
  58 #define list_for_each_dir(pos, head, is_reverse) \
  59         for (pos = is_reverse ? (head)->prev : (head)->next; \
  60                 pos != (head); \
  61                 pos = is_reverse ? pos->prev : pos->next)
  62
  63 static int after_or_end(enum action_where where)
  64 {
  65         return (where == WHERE_AFTER) || (where == WHERE_END);
  66 }
  67
  68 /*
  69  * Return the length of the string not including any final
  70  * punctuation. E.g., the input "Signed-off-by:" would return
  71  * 13, stripping the trailing punctuation but retaining
  72  * internal punctuation.
  73  */
  74 static size_t token_len_without_separator(const char *token, size_t len)
  75 {
  76         while (len > 0 && !isalnum(token[len - 1]))
  77                 len--;
  78         return len;
  79 }
  80
  81 static int same_token(struct trailer_item *a, struct arg_item *b)
  82 {
  83         size_t a_len, b_len, min_len;
  84
  85         if (!a->token)
  86                 return 0;
  87
  88         a_len = token_len_without_separator(a->token, strlen(a->token));
  89         b_len = token_len_without_separator(b->token, strlen(b->token));
  90         min_len = (a_len > b_len) ? b_len : a_len;
  91
  92         return !strncasecmp(a->token, b->token, min_len);
  93 }
  94
  95 static int same_value(struct trailer_item *a, struct arg_item *b)
  96 {
  97         return !strcasecmp(a->value, b->value);
  98 }
  99
 100 static int same_trailer(struct trailer_item *a, struct arg_item *b)
 101 {
 102         return same_token(a, b) && same_value(a, b);
 103 }
 104
 105 static inline int contains_only_spaces(const char *str)
 106 {
 107         const char *s = str;
 108         while (*s && isspace(*s))
 109                 s++;
 110         return !*s;
 111 }
 112
 113 static inline void strbuf_replace(struct strbuf *sb, const char *a, const char *b)
 114 {
 115         const char *ptr = strstr(sb->buf, a);
 116         if (ptr)
 117                 strbuf_splice(sb, ptr - sb->buf, strlen(a), b, strlen(b));
 118 }
 119
 120 static void free_trailer_item(struct trailer_item *item)
 121 {
 122         free(item->token);
 123         free(item->value);
 124         free(item);
 125 }
 126
 127 static void free_arg_item(struct arg_item *item)
 128 {
 129         free(item->conf.name);
 130         free(item->conf.key);
 131         free(item->conf.command);
 132         free(item->token);
 133         free(item->value);
 134         free(item);
 135 }
 136
 137 static char last_non_space_char(const char *s)
 138 {
 139         int i;
 140         for (i = strlen(s) - 1; i >= 0; i--)
 141                 if (!isspace(s[i]))
 142                         return s[i];
 143         return '\0';
 144 }
 145
 146 static void print_tok_val(FILE *outfile, const char *tok, const char *val)
 147 {
 148         char c;
 149
 150         if (!tok) {
 151                 fprintf(outfile, "%s\n", val);
 152                 return;
 153         }
 154
 155         c = last_non_space_char(tok);
 156         if (!c)
 157                 return;
 158         if (strchr(separators, c))
 159                 fprintf(outfile, "%s%s\n", tok, val);
 160         else
 161                 fprintf(outfile, "%s%c %s\n", tok, separators[0], val);
 162 }
 163
 164 static void print_all(FILE *outfile, struct list_head *head, int trim_empty)
 165 {
 166         struct list_head *pos;
 167         struct trailer_item *item;
 168         list_for_each(pos, head) {
 169                 item = list_entry(pos, struct trailer_item, list);
 170                 if (!trim_empty || strlen(item->value) > 0)
 171                         print_tok_val(outfile, item->token, item->value);
 172         }
 173 }
 174
 175 static struct trailer_item *trailer_from_arg(struct arg_item *arg_tok)
 176 {
 177         struct trailer_item *new = xcalloc(sizeof(*new), 1);
 178         new->token = arg_tok->token;
 179         new->value = arg_tok->value;
 180         arg_tok->token = arg_tok->value = NULL;
 181         free_arg_item(arg_tok);
 182         return new;
 183 }
 184
 185 static void add_arg_to_input_list(struct trailer_item *on_tok,
 186                                   struct arg_item *arg_tok)
 187 {
 188         int aoe = after_or_end(arg_tok->conf.where);
 189         struct trailer_item *to_add = trailer_from_arg(arg_tok);
 190         if (aoe)
 191                 list_add(&to_add->list, &on_tok->list);
 192         else
 193                 list_add_tail(&to_add->list, &on_tok->list);
 194 }
 195
 196 static int check_if_different(struct trailer_item *in_tok,
 197                               struct arg_item *arg_tok,
 198                               int check_all,
 199                               struct list_head *head)
 200 {
 201         enum action_where where = arg_tok->conf.where;
 202         struct list_head *next_head;
 203         do {
 204                 if (same_trailer(in_tok, arg_tok))
 205                         return 0;
 206                 /*
 207                  * if we want to add a trailer after another one,
 208                  * we have to check those before this one
 209                  */
 210                 next_head = after_or_end(where) ? in_tok->list.prev
 211                                                 : in_tok->list.next;
 212                 if (next_head == head)
 213                         break;
 214                 in_tok = list_entry(next_head, struct trailer_item, list);
 215         } while (check_all);
 216         return 1;
 217 }
 218
 219 static char *apply_command(const char *command, const char *arg)
 220 {
 221         struct strbuf cmd = STRBUF_INIT;
 222         struct strbuf buf = STRBUF_INIT;
 223         struct child_process cp = CHILD_PROCESS_INIT;
 224         const char *argv[] = {NULL, NULL};
 225         char *result;
 226
 227         strbuf_addstr(&cmd, command);
 228         if (arg)
 229                 strbuf_replace(&cmd, TRAILER_ARG_STRING, arg);
 230
 231         argv[0] = cmd.buf;
 232         cp.argv = argv;
 233         cp.env = local_repo_env;
 234         cp.no_stdin = 1;
 235         cp.use_shell = 1;
 236
 237         if (capture_command(&cp, &buf, 1024)) {
 238                 error(_("running trailer command '%s' failed"), cmd.buf);
 239                 strbuf_release(&buf);
 240                 result = xstrdup("");
 241         } else {
 242                 strbuf_trim(&buf);
 243                 result = strbuf_detach(&buf, NULL);
 244         }
 245
 246         strbuf_release(&cmd);
 247         return result;
 248 }
 249
 250 static void apply_item_command(struct trailer_item *in_tok, struct arg_item *arg_tok)
 251 {
 252         if (arg_tok->conf.command) {
 253                 const char *arg;
 254                 if (arg_tok->value && arg_tok->value[0]) {
 255                         arg = arg_tok->value;
 256                 } else {
 257                         if (in_tok && in_tok->value)
 258                                 arg = xstrdup(in_tok->value);
 259                         else
 260                                 arg = xstrdup("");
 261                 }
 262                 arg_tok->value = apply_command(arg_tok->conf.command, arg);
 263                 free((char *)arg);
 264         }
 265 }
 266
 267 static void apply_arg_if_exists(struct trailer_item *in_tok,
 268                                 struct arg_item *arg_tok,
 269                                 struct trailer_item *on_tok,
 270                                 struct list_head *head)
 271 {
 272         switch (arg_tok->conf.if_exists) {
 273         case EXISTS_DO_NOTHING:
 274                 free_arg_item(arg_tok);
 275                 break;
 276         case EXISTS_REPLACE:
 277                 apply_item_command(in_tok, arg_tok);
 278                 add_arg_to_input_list(on_tok, arg_tok);
 279                 list_del(&in_tok->list);
 280                 free_trailer_item(in_tok);
 281                 break;
 282         case EXISTS_ADD:
 283                 apply_item_command(in_tok, arg_tok);
 284                 add_arg_to_input_list(on_tok, arg_tok);
 285                 break;
 286         case EXISTS_ADD_IF_DIFFERENT:
 287                 apply_item_command(in_tok, arg_tok);
 288                 if (check_if_different(in_tok, arg_tok, 1, head))
 289                         add_arg_to_input_list(on_tok, arg_tok);
 290                 else
 291                         free_arg_item(arg_tok);
 292                 break;
 293         case EXISTS_ADD_IF_DIFFERENT_NEIGHBOR:
 294                 apply_item_command(in_tok, arg_tok);
 295                 if (check_if_different(on_tok, arg_tok, 0, head))
 296                         add_arg_to_input_list(on_tok, arg_tok);
 297                 else
 298                         free_arg_item(arg_tok);
 299                 break;
 300         }
 301 }
 302
 303 static void apply_arg_if_missing(struct list_head *head,
 304                                  struct arg_item *arg_tok)
 305 {
 306         enum action_where where;
 307         struct trailer_item *to_add;
 308
 309         switch (arg_tok->conf.if_missing) {
 310         case MISSING_DO_NOTHING:
 311                 free_arg_item(arg_tok);
 312                 break;
 313         case MISSING_ADD:
 314                 where = arg_tok->conf.where;
 315                 apply_item_command(NULL, arg_tok);
 316                 to_add = trailer_from_arg(arg_tok);
 317                 if (after_or_end(where))
 318                         list_add_tail(&to_add->list, head);
 319                 else
 320                         list_add(&to_add->list, head);
 321         }
 322 }
 323
 324 static int find_same_and_apply_arg(struct list_head *head,
 325                                    struct arg_item *arg_tok)
 326 {
 327         struct list_head *pos;
 328         struct trailer_item *in_tok;
 329         struct trailer_item *on_tok;
 330
 331         enum action_where where = arg_tok->conf.where;
 332         int middle = (where == WHERE_AFTER) || (where == WHERE_BEFORE);
 333         int backwards = after_or_end(where);
 334         struct trailer_item *start_tok;
 335
 336         if (list_empty(head))
 337                 return 0;
 338
 339         start_tok = list_entry(backwards ? head->prev : head->next,
 340                                struct trailer_item,
 341                                list);
 342
 343         list_for_each_dir(pos, head, backwards) {
 344                 in_tok = list_entry(pos, struct trailer_item, list);
 345                 if (!same_token(in_tok, arg_tok))
 346                         continue;
 347                 on_tok = middle ? in_tok : start_tok;
 348                 apply_arg_if_exists(in_tok, arg_tok, on_tok, head);
 349                 return 1;
 350         }
 351         return 0;
 352 }
 353
 354 static void process_trailers_lists(struct list_head *head,
 355                                    struct list_head *arg_head)
 356 {
 357         struct list_head *pos, *p;
 358         struct arg_item *arg_tok;
 359
 360         list_for_each_safe(pos, p, arg_head) {
 361                 int applied = 0;
 362                 arg_tok = list_entry(pos, struct arg_item, list);
 363
 364                 list_del(pos);
 365
 366                 applied = find_same_and_apply_arg(head, arg_tok);
 367
 368                 if (!applied)
 369                         apply_arg_if_missing(head, arg_tok);
 370         }
 371 }
 372
 373 static int set_where(struct conf_info *item, const char *value)
 374 {
 375         if (!strcasecmp("after", value))
 376                 item->where = WHERE_AFTER;
 377         else if (!strcasecmp("before", value))
 378                 item->where = WHERE_BEFORE;
 379         else if (!strcasecmp("end", value))
 380                 item->where = WHERE_END;
 381         else if (!strcasecmp("start", value))
 382                 item->where = WHERE_START;
 383         else
 384                 return -1;
 385         return 0;
 386 }
 387
 388 static int set_if_exists(struct conf_info *item, const char *value)
 389 {
 390         if (!strcasecmp("addIfDifferent", value))
 391                 item->if_exists = EXISTS_ADD_IF_DIFFERENT;
 392         else if (!strcasecmp("addIfDifferentNeighbor", value))
 393                 item->if_exists = EXISTS_ADD_IF_DIFFERENT_NEIGHBOR;
 394         else if (!strcasecmp("add", value))
 395                 item->if_exists = EXISTS_ADD;
 396         else if (!strcasecmp("replace", value))
 397                 item->if_exists = EXISTS_REPLACE;
 398         else if (!strcasecmp("doNothing", value))
 399                 item->if_exists = EXISTS_DO_NOTHING;
 400         else
 401                 return -1;
 402         return 0;
 403 }
 404
 405 static int set_if_missing(struct conf_info *item, const char *value)
 406 {
 407         if (!strcasecmp("doNothing", value))
 408                 item->if_missing = MISSING_DO_NOTHING;
 409         else if (!strcasecmp("add", value))
 410                 item->if_missing = MISSING_ADD;
 411         else
 412                 return -1;
 413         return 0;
 414 }
 415
 416 static void duplicate_conf(struct conf_info *dst, const struct conf_info *src)
 417 {
 418         *dst = *src;
 419         dst->name = xstrdup_or_null(src->name);
 420         dst->key = xstrdup_or_null(src->key);
 421         dst->command = xstrdup_or_null(src->command);
 422 }
 423
 424 static struct arg_item *get_conf_item(const char *name)
 425 {
 426         struct list_head *pos;
 427         struct arg_item *item;
 428
 429         /* Look up item with same name */
 430         list_for_each(pos, &conf_head) {
 431                 item = list_entry(pos, struct arg_item, list);
 432                 if (!strcasecmp(item->conf.name, name))
 433                         return item;
 434         }
 435
 436         /* Item does not already exists, create it */
 437         item = xcalloc(sizeof(*item), 1);
 438         duplicate_conf(&item->conf, &default_conf_info);
 439         item->conf.name = xstrdup(name);
 440
 441         list_add_tail(&item->list, &conf_head);
 442
 443         return item;
 444 }
 445
 446 enum trailer_info_type { TRAILER_KEY, TRAILER_COMMAND, TRAILER_WHERE,
 447                          TRAILER_IF_EXISTS, TRAILER_IF_MISSING };
 448
 449 static struct {
 450         const char *name;
 451         enum trailer_info_type type;
 452 } trailer_config_items[] = {
 453         { "key", TRAILER_KEY },
 454         { "command", TRAILER_COMMAND },
 455         { "where", TRAILER_WHERE },
 456         { "ifexists", TRAILER_IF_EXISTS },
 457         { "ifmissing", TRAILER_IF_MISSING }
 458 };
 459
 460 static int git_trailer_default_config(const char *conf_key, const char *value, void *cb)
 461 {
 462         const char *trailer_item, *variable_name;
 463
 464         if (!skip_prefix(conf_key, "trailer.", &trailer_item))
 465                 return 0;
 466
 467         variable_name = strrchr(trailer_item, '.');
 468         if (!variable_name) {
 469                 if (!strcmp(trailer_item, "where")) {
 470                         if (set_where(&default_conf_info, value) < 0)
 471                                 warning(_("unknown value '%s' for key '%s'"),
 472                                         value, conf_key);
 473                 } else if (!strcmp(trailer_item, "ifexists")) {
 474                         if (set_if_exists(&default_conf_info, value) < 0)
 475                                 warning(_("unknown value '%s' for key '%s'"),
 476                                         value, conf_key);
 477                 } else if (!strcmp(trailer_item, "ifmissing")) {
 478                         if (set_if_missing(&default_conf_info, value) < 0)
 479                                 warning(_("unknown value '%s' for key '%s'"),
 480                                         value, conf_key);
 481                 } else if (!strcmp(trailer_item, "separators")) {
 482                         separators = xstrdup(value);
 483                 }
 484         }
 485         return 0;
 486 }
 487
 488 static int git_trailer_config(const char *conf_key, const char *value, void *cb)
 489 {
 490         const char *trailer_item, *variable_name;
 491         struct arg_item *item;
 492         struct conf_info *conf;
 493         char *name = NULL;
 494         enum trailer_info_type type;
 495         int i;
 496
 497         if (!skip_prefix(conf_key, "trailer.", &trailer_item))
 498                 return 0;
 499
 500         variable_name = strrchr(trailer_item, '.');
 501         if (!variable_name)
 502                 return 0;
 503
 504         variable_name++;
 505         for (i = 0; i < ARRAY_SIZE(trailer_config_items); i++) {
 506                 if (strcmp(trailer_config_items[i].name, variable_name))
 507                         continue;
 508                 name = xstrndup(trailer_item,  variable_name - trailer_item - 1);
 509                 type = trailer_config_items[i].type;
 510                 break;
 511         }
 512
 513         if (!name)
 514                 return 0;
 515
 516         item = get_conf_item(name);
 517         conf = &item->conf;
 518         free(name);
 519
 520         switch (type) {
 521         case TRAILER_KEY:
 522                 if (conf->key)
 523                         warning(_("more than one %s"), conf_key);
 524                 conf->key = xstrdup(value);
 525                 break;
 526         case TRAILER_COMMAND:
 527                 if (conf->command)
 528                         warning(_("more than one %s"), conf_key);
 529                 conf->command = xstrdup(value);
 530                 break;
 531         case TRAILER_WHERE:
 532                 if (set_where(conf, value))
 533                         warning(_("unknown value '%s' for key '%s'"), value, conf_key);
 534                 break;
 535         case TRAILER_IF_EXISTS:
 536                 if (set_if_exists(conf, value))
 537                         warning(_("unknown value '%s' for key '%s'"), value, conf_key);
 538                 break;
 539         case TRAILER_IF_MISSING:
 540                 if (set_if_missing(conf, value))
 541                         warning(_("unknown value '%s' for key '%s'"), value, conf_key);
 542                 break;
 543         default:
 544                 die("BUG: trailer.c: unhandled type %d", type);
 545         }
 546         return 0;
 547 }
 548
 549 static const char *token_from_item(struct arg_item *item, char *tok)
 550 {
 551         if (item->conf.key)
 552                 return item->conf.key;
 553         if (tok)
 554                 return tok;
 555         return item->conf.name;
 556 }
 557
 558 static int token_matches_item(const char *tok, struct arg_item *item, int tok_len)
 559 {
 560         if (!strncasecmp(tok, item->conf.name, tok_len))
 561                 return 1;
 562         return item->conf.key ? !strncasecmp(tok, item->conf.key, tok_len) : 0;
 563 }
 564
 565 /*
 566  * Return the location of the first separator in line, or -1 if there is no
 567  * separator.
 568  */
 569 static int find_separator(const char *line, const char *separators)
 570 {
 571         int loc = strcspn(line, separators);
 572         if (!line[loc])
 573                 return -1;
 574         return loc;
 575 }
 576
 577 /*
 578  * Obtain the token, value, and conf from the given trailer.
 579  *
 580  * separator_pos must not be 0, since the token cannot be an empty string.
 581  *
 582  * If separator_pos is -1, interpret the whole trailer as a token.
 583  */
 584 static void parse_trailer(struct strbuf *tok, struct strbuf *val,
 585                          const struct conf_info **conf, const char *trailer,
 586                          int separator_pos)
 587 {
 588         struct arg_item *item;
 589         int tok_len;
 590         struct list_head *pos;
 591
 592         if (separator_pos != -1) {
 593                 strbuf_add(tok, trailer, separator_pos);
 594                 strbuf_trim(tok);
 595                 strbuf_addstr(val, trailer + separator_pos + 1);
 596                 strbuf_trim(val);
 597         } else {
 598                 strbuf_addstr(tok, trailer);
 599                 strbuf_trim(tok);
 600         }
 601
 602         /* Lookup if the token matches something in the config */
 603         tok_len = token_len_without_separator(tok->buf, tok->len);
 604         if (conf)
 605                 *conf = &default_conf_info;
 606         list_for_each(pos, &conf_head) {
 607                 item = list_entry(pos, struct arg_item, list);
 608                 if (token_matches_item(tok->buf, item, tok_len)) {
 609                         char *tok_buf = strbuf_detach(tok, NULL);
 610                         if (conf)
 611                                 *conf = &item->conf;
 612                         strbuf_addstr(tok, token_from_item(item, tok_buf));
 613                         free(tok_buf);
 614                         break;
 615                 }
 616         }
 617 }
 618
 619 static struct trailer_item *add_trailer_item(struct list_head *head, char *tok,
 620                                              char *val)
 621 {
 622         struct trailer_item *new = xcalloc(sizeof(*new), 1);
 623         new->token = tok;
 624         new->value = val;
 625         list_add_tail(&new->list, head);
 626         return new;
 627 }
 628
 629 static void add_arg_item(struct list_head *arg_head, char *tok, char *val,
 630                          const struct conf_info *conf)
 631 {
 632         struct arg_item *new = xcalloc(sizeof(*new), 1);
 633         new->token = tok;
 634         new->value = val;
 635         duplicate_conf(&new->conf, conf);
 636         list_add_tail(&new->list, arg_head);
 637 }
 638
 639 static void process_command_line_args(struct list_head *arg_head,
 640                                       struct string_list *trailers)
 641 {
 642         struct string_list_item *tr;
 643         struct arg_item *item;
 644         struct strbuf tok = STRBUF_INIT;
 645         struct strbuf val = STRBUF_INIT;
 646         const struct conf_info *conf;
 647         struct list_head *pos;
 648
 649         /*
 650          * In command-line arguments, '=' is accepted (in addition to the
 651          * separators that are defined).
 652          */
 653         char *cl_separators = xstrfmt("=%s", separators);
 654
 655         /* Add an arg item for each configured trailer with a command */
 656         list_for_each(pos, &conf_head) {
 657                 item = list_entry(pos, struct arg_item, list);
 658                 if (item->conf.command)
 659                         add_arg_item(arg_head,
 660                                      xstrdup(token_from_item(item, NULL)),
 661                                      xstrdup(""),
 662                                      &item->conf);
 663         }
 664
 665         /* Add an arg item for each trailer on the command line */
 666         for_each_string_list_item(tr, trailers) {
 667                 int separator_pos = find_separator(tr->string, cl_separators);
 668                 if (separator_pos == 0) {
 669                         struct strbuf sb = STRBUF_INIT;
 670                         strbuf_addstr(&sb, tr->string);
 671                         strbuf_trim(&sb);
 672                         error(_("empty trailer token in trailer '%.*s'"),
 673                               (int) sb.len, sb.buf);
 674                         strbuf_release(&sb);
 675                 } else {
 676                         parse_trailer(&tok, &val, &conf, tr->string,
 677                                       separator_pos);
 678                         add_arg_item(arg_head,
 679                                      strbuf_detach(&tok, NULL),
 680                                      strbuf_detach(&val, NULL),
 681                                      conf);
 682                 }
 683         }
 684
 685         free(cl_separators);
 686 }
 687
 688 static struct strbuf **read_input_file(const char *file)
 689 {
 690         struct strbuf **lines;
 691         struct strbuf sb = STRBUF_INIT;
 692
 693         if (file) {
 694                 if (strbuf_read_file(&sb, file, 0) < 0)
 695                         die_errno(_("could not read input file '%s'"), file);
 696         } else {
 697                 if (strbuf_read(&sb, fileno(stdin), 0) < 0)
 698                         die_errno(_("could not read from stdin"));
 699         }
 700
 701         lines = strbuf_split(&sb, '\n');
 702
 703         strbuf_release(&sb);
 704
 705         return lines;
 706 }
 707
 708 /*
 709  * Return the (0 based) index of the start of the patch or the line
 710  * count if there is no patch in the message.
 711  */
 712 static int find_patch_start(struct strbuf **lines, int count)
 713 {
 714         int i;
 715
 716         /* Get the start of the patch part if any */
 717         for (i = 0; i < count; i++) {
 718                 if (starts_with(lines[i]->buf, "---"))
 719                         return i;
 720         }
 721
 722         return count;
 723 }
 724
 725 /*
 726  * Return the (0 based) index of the first trailer line or count if
 727  * there are no trailers. Trailers are searched only in the lines from
 728  * index (count - 1) down to index 0.
 729  */
 730 static int find_trailer_start(struct strbuf **lines, int count)
 731 {
 732         int start, end_of_title, only_spaces = 1;
 733         int recognized_prefix = 0, trailer_lines = 0, non_trailer_lines = 0;
 734         /*
 735          * Number of possible continuation lines encountered. This will be
 736          * reset to 0 if we encounter a trailer (since those lines are to be
 737          * considered continuations of that trailer), and added to
 738          * non_trailer_lines if we encounter a non-trailer (since those lines
 739          * are to be considered non-trailers).
 740          */
 741         int possible_continuation_lines = 0;
 742
 743         /* The first paragraph is the title and cannot be trailers */
 744         for (start = 0; start < count; start++) {
 745                 if (lines[start]->buf[0] == comment_line_char)
 746                         continue;
 747                 if (contains_only_spaces(lines[start]->buf))
 748                         break;
 749         }
 750         end_of_title = start;
 751
 752         /*
 753          * Get the start of the trailers by looking starting from the end for a
 754          * blank line before a set of non-blank lines that (i) are all
 755          * trailers, or (ii) contains at least one Git-generated trailer and
 756          * consists of at least 25% trailers.
 757          */
 758         for (start = count - 1; start >= end_of_title; start--) {
 759                 const char **p;
 760                 int separator_pos;
 761
 762                 if (lines[start]->buf[0] == comment_line_char) {
 763                         non_trailer_lines += possible_continuation_lines;
 764                         possible_continuation_lines = 0;
 765                         continue;
 766                 }
 767                 if (contains_only_spaces(lines[start]->buf)) {
 768                         if (only_spaces)
 769                                 continue;
 770                         non_trailer_lines += possible_continuation_lines;
 771                         if (recognized_prefix &&
 772                             trailer_lines * 3 >= non_trailer_lines)
 773                                 return start + 1;
 774                         if (trailer_lines && !non_trailer_lines)
 775                                 return start + 1;
 776                         return count;
 777                 }
 778                 only_spaces = 0;
 779
 780                 for (p = git_generated_prefixes; *p; p++) {
 781                         if (starts_with(lines[start]->buf, *p)) {
 782                                 trailer_lines++;
 783                                 possible_continuation_lines = 0;
 784                                 recognized_prefix = 1;
 785                                 goto continue_outer_loop;
 786                         }
 787                 }
 788
 789                 separator_pos = find_separator(lines[start]->buf, separators);
 790                 if (separator_pos >= 1 && !isspace(lines[start]->buf[0])) {
 791                         struct list_head *pos;
 792
 793                         trailer_lines++;
 794                         possible_continuation_lines = 0;
 795                         if (recognized_prefix)
 796                                 continue;
 797                         list_for_each(pos, &conf_head) {
 798                                 struct arg_item *item;
 799                                 item = list_entry(pos, struct arg_item, list);
 800                                 if (token_matches_item(lines[start]->buf, item,
 801                                                        separator_pos)) {
 802                                         recognized_prefix = 1;
 803                                         break;
 804                                 }
 805                         }
 806                 } else if (isspace(lines[start]->buf[0]))
 807                         possible_continuation_lines++;
 808                 else {
 809                         non_trailer_lines++;
 810                         non_trailer_lines += possible_continuation_lines;
 811                         possible_continuation_lines = 0;
 812                 }
 813 continue_outer_loop:
 814                 ;
 815         }
 816
 817         return count;
 818 }
 819
 820 /* Get the index of the end of the trailers */
 821 static int find_trailer_end(struct strbuf **lines, int patch_start)
 822 {
 823         struct strbuf sb = STRBUF_INIT;
 824         int i, ignore_bytes;
 825
 826         for (i = 0; i < patch_start; i++)
 827                 strbuf_addbuf(&sb, lines[i]);
 828         ignore_bytes = ignore_non_trailer(&sb);
 829         strbuf_release(&sb);
 830         for (i = patch_start - 1; i >= 0 && ignore_bytes > 0; i--)
 831                 ignore_bytes -= lines[i]->len;
 832
 833         return i + 1;
 834 }
 835
 836 static int has_blank_line_before(struct strbuf **lines, int start)
 837 {
 838         for (;start >= 0; start--) {
 839                 if (lines[start]->buf[0] == comment_line_char)
 840                         continue;
 841                 return contains_only_spaces(lines[start]->buf);
 842         }
 843         return 0;
 844 }
 845
 846 static void print_lines(FILE *outfile, struct strbuf **lines, int start, int end)
 847 {
 848         int i;
 849         for (i = start; lines[i] && i < end; i++)
 850                 fprintf(outfile, "%s", lines[i]->buf);
 851 }
 852
 853 static int process_input_file(FILE *outfile,
 854                               struct strbuf **lines,
 855                               struct list_head *head)
 856 {
 857         int count = 0;
 858         int patch_start, trailer_start, trailer_end, i;
 859         struct strbuf tok = STRBUF_INIT;
 860         struct strbuf val = STRBUF_INIT;
 861         struct trailer_item *last = NULL;
 862
 863         /* Get the line count */
 864         while (lines[count])
 865                 count++;
 866
 867         patch_start = find_patch_start(lines, count);
 868         trailer_end = find_trailer_end(lines, patch_start);
 869         trailer_start = find_trailer_start(lines, trailer_end);
 870
 871         /* Print lines before the trailers as is */
 872         print_lines(outfile, lines, 0, trailer_start);
 873
 874         if (!has_blank_line_before(lines, trailer_start - 1))
 875                 fprintf(outfile, "\n");
 876
 877         /* Parse trailer lines */
 878         for (i = trailer_start; i < trailer_end; i++) {
 879                 int separator_pos;
 880                 if (lines[i]->buf[0] == comment_line_char)
 881                         continue;
 882                 if (last && isspace(lines[i]->buf[0])) {
 883                         struct strbuf sb = STRBUF_INIT;
 884                         strbuf_addf(&sb, "%s\n%s", last->value, lines[i]->buf);
 885                         strbuf_strip_suffix(&sb, "\n");
 886                         free(last->value);
 887                         last->value = strbuf_detach(&sb, NULL);
 888                         continue;
 889                 }
 890                 separator_pos = find_separator(lines[i]->buf, separators);
 891                 if (separator_pos >= 1) {
 892                         parse_trailer(&tok, &val, NULL, lines[i]->buf,
 893                                       separator_pos);
 894                         last = add_trailer_item(head,
 895                                                 strbuf_detach(&tok, NULL),
 896                                                 strbuf_detach(&val, NULL));
 897                 } else {
 898                         strbuf_addbuf(&val, lines[i]);
 899                         strbuf_strip_suffix(&val, "\n");
 900                         add_trailer_item(head,
 901                                          NULL,
 902                                          strbuf_detach(&val, NULL));
 903                         last = NULL;
 904                 }
 905         }
 906
 907         return trailer_end;
 908 }
 909
 910 static void free_all(struct list_head *head)
 911 {
 912         struct list_head *pos, *p;
 913         list_for_each_safe(pos, p, head) {
 914                 list_del(pos);
 915                 free_trailer_item(list_entry(pos, struct trailer_item, list));
 916         }
 917 }
 918
 919 static struct tempfile trailers_tempfile;
 920
 921 static FILE *create_in_place_tempfile(const char *file)
 922 {
 923         struct stat st;
 924         struct strbuf template = STRBUF_INIT;
 925         const char *tail;
 926         FILE *outfile;
 927
 928         if (stat(file, &st))
 929                 die_errno(_("could not stat %s"), file);
 930         if (!S_ISREG(st.st_mode))
 931                 die(_("file %s is not a regular file"), file);
 932         if (!(st.st_mode & S_IWUSR))
 933                 die(_("file %s is not writable by user"), file);
 934
 935         /* Create temporary file in the same directory as the original */
 936         tail = strrchr(file, '/');
 937         if (tail != NULL)
 938                 strbuf_add(&template, file, tail - file + 1);
 939         strbuf_addstr(&template, "git-interpret-trailers-XXXXXX");
 940
 941         xmks_tempfile_m(&trailers_tempfile, template.buf, st.st_mode);
 942         strbuf_release(&template);
 943         outfile = fdopen_tempfile(&trailers_tempfile, "w");
 944         if (!outfile)
 945                 die_errno(_("could not open temporary file"));
 946
 947         return outfile;
 948 }
 949
 950 void process_trailers(const char *file, int in_place, int trim_empty, struct string_list *trailers)
 951 {
 952         LIST_HEAD(head);
 953         LIST_HEAD(arg_head);
 954         struct strbuf **lines;
 955         int trailer_end;
 956         FILE *outfile = stdout;
 957
 958         /* Default config must be setup first */
 959         git_config(git_trailer_default_config, NULL);
 960         git_config(git_trailer_config, NULL);
 961
 962         lines = read_input_file(file);
 963
 964         if (in_place)
 965                 outfile = create_in_place_tempfile(file);
 966
 967         /* Print the lines before the trailers */
 968         trailer_end = process_input_file(outfile, lines, &head);
 969
 970         process_command_line_args(&arg_head, trailers);
 971
 972         process_trailers_lists(&head, &arg_head);
 973
 974         print_all(outfile, &head, trim_empty);
 975
 976         free_all(&head);
 977
 978         /* Print the lines after the trailers as is */
 979         print_lines(outfile, lines, trailer_end, INT_MAX);
 980
 981         if (in_place)
 982                 if (rename_tempfile(&trailers_tempfile, file))
 983                         die_errno(_("could not rename temporary file to %s"), file);
 984
 985         strbuf_list_free(lines);
 986 }