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         if (src->name)
 420                 dst->name = xstrdup(src->name);
 421         if (src->key)
 422                 dst->key = xstrdup(src->key);
 423         if (src->command)
 424                 dst->command = xstrdup(src->command);
 425 }
 426
 427 static struct arg_item *get_conf_item(const char *name)
 428 {
 429         struct list_head *pos;
 430         struct arg_item *item;
 431
 432         /* Look up item with same name */
 433         list_for_each(pos, &conf_head) {
 434                 item = list_entry(pos, struct arg_item, list);
 435                 if (!strcasecmp(item->conf.name, name))
 436                         return item;
 437         }
 438
 439         /* Item does not already exists, create it */
 440         item = xcalloc(sizeof(*item), 1);
 441         duplicate_conf(&item->conf, &default_conf_info);
 442         item->conf.name = xstrdup(name);
 443
 444         list_add_tail(&item->list, &conf_head);
 445
 446         return item;
 447 }
 448
 449 enum trailer_info_type { TRAILER_KEY, TRAILER_COMMAND, TRAILER_WHERE,
 450                          TRAILER_IF_EXISTS, TRAILER_IF_MISSING };
 451
 452 static struct {
 453         const char *name;
 454         enum trailer_info_type type;
 455 } trailer_config_items[] = {
 456         { "key", TRAILER_KEY },
 457         { "command", TRAILER_COMMAND },
 458         { "where", TRAILER_WHERE },
 459         { "ifexists", TRAILER_IF_EXISTS },
 460         { "ifmissing", TRAILER_IF_MISSING }
 461 };
 462
 463 static int git_trailer_default_config(const char *conf_key, const char *value, void *cb)
 464 {
 465         const char *trailer_item, *variable_name;
 466
 467         if (!skip_prefix(conf_key, "trailer.", &trailer_item))
 468                 return 0;
 469
 470         variable_name = strrchr(trailer_item, '.');
 471         if (!variable_name) {
 472                 if (!strcmp(trailer_item, "where")) {
 473                         if (set_where(&default_conf_info, value) < 0)
 474                                 warning(_("unknown value '%s' for key '%s'"),
 475                                         value, conf_key);
 476                 } else if (!strcmp(trailer_item, "ifexists")) {
 477                         if (set_if_exists(&default_conf_info, value) < 0)
 478                                 warning(_("unknown value '%s' for key '%s'"),
 479                                         value, conf_key);
 480                 } else if (!strcmp(trailer_item, "ifmissing")) {
 481                         if (set_if_missing(&default_conf_info, value) < 0)
 482                                 warning(_("unknown value '%s' for key '%s'"),
 483                                         value, conf_key);
 484                 } else if (!strcmp(trailer_item, "separators")) {
 485                         separators = xstrdup(value);
 486                 }
 487         }
 488         return 0;
 489 }
 490
 491 static int git_trailer_config(const char *conf_key, const char *value, void *cb)
 492 {
 493         const char *trailer_item, *variable_name;
 494         struct arg_item *item;
 495         struct conf_info *conf;
 496         char *name = NULL;
 497         enum trailer_info_type type;
 498         int i;
 499
 500         if (!skip_prefix(conf_key, "trailer.", &trailer_item))
 501                 return 0;
 502
 503         variable_name = strrchr(trailer_item, '.');
 504         if (!variable_name)
 505                 return 0;
 506
 507         variable_name++;
 508         for (i = 0; i < ARRAY_SIZE(trailer_config_items); i++) {
 509                 if (strcmp(trailer_config_items[i].name, variable_name))
 510                         continue;
 511                 name = xstrndup(trailer_item,  variable_name - trailer_item - 1);
 512                 type = trailer_config_items[i].type;
 513                 break;
 514         }
 515
 516         if (!name)
 517                 return 0;
 518
 519         item = get_conf_item(name);
 520         conf = &item->conf;
 521         free(name);
 522
 523         switch (type) {
 524         case TRAILER_KEY:
 525                 if (conf->key)
 526                         warning(_("more than one %s"), conf_key);
 527                 conf->key = xstrdup(value);
 528                 break;
 529         case TRAILER_COMMAND:
 530                 if (conf->command)
 531                         warning(_("more than one %s"), conf_key);
 532                 conf->command = xstrdup(value);
 533                 break;
 534         case TRAILER_WHERE:
 535                 if (set_where(conf, value))
 536                         warning(_("unknown value '%s' for key '%s'"), value, conf_key);
 537                 break;
 538         case TRAILER_IF_EXISTS:
 539                 if (set_if_exists(conf, value))
 540                         warning(_("unknown value '%s' for key '%s'"), value, conf_key);
 541                 break;
 542         case TRAILER_IF_MISSING:
 543                 if (set_if_missing(conf, value))
 544                         warning(_("unknown value '%s' for key '%s'"), value, conf_key);
 545                 break;
 546         default:
 547                 die("BUG: trailer.c: unhandled type %d", type);
 548         }
 549         return 0;
 550 }
 551
 552 static const char *token_from_item(struct arg_item *item, char *tok)
 553 {
 554         if (item->conf.key)
 555                 return item->conf.key;
 556         if (tok)
 557                 return tok;
 558         return item->conf.name;
 559 }
 560
 561 static int token_matches_item(const char *tok, struct arg_item *item, int tok_len)
 562 {
 563         if (!strncasecmp(tok, item->conf.name, tok_len))
 564                 return 1;
 565         return item->conf.key ? !strncasecmp(tok, item->conf.key, tok_len) : 0;
 566 }
 567
 568 /*
 569  * Return the location of the first separator in line, or -1 if there is no
 570  * separator.
 571  */
 572 static int find_separator(const char *line, const char *separators)
 573 {
 574         int loc = strcspn(line, separators);
 575         if (!line[loc])
 576                 return -1;
 577         return loc;
 578 }
 579
 580 /*
 581  * Obtain the token, value, and conf from the given trailer.
 582  *
 583  * separator_pos must not be 0, since the token cannot be an empty string.
 584  *
 585  * If separator_pos is -1, interpret the whole trailer as a token.
 586  */
 587 static void parse_trailer(struct strbuf *tok, struct strbuf *val,
 588                          const struct conf_info **conf, const char *trailer,
 589                          int separator_pos)
 590 {
 591         struct arg_item *item;
 592         int tok_len;
 593         struct list_head *pos;
 594
 595         if (separator_pos != -1) {
 596                 strbuf_add(tok, trailer, separator_pos);
 597                 strbuf_trim(tok);
 598                 strbuf_addstr(val, trailer + separator_pos + 1);
 599                 strbuf_trim(val);
 600         } else {
 601                 strbuf_addstr(tok, trailer);
 602                 strbuf_trim(tok);
 603         }
 604
 605         /* Lookup if the token matches something in the config */
 606         tok_len = token_len_without_separator(tok->buf, tok->len);
 607         if (conf)
 608                 *conf = &default_conf_info;
 609         list_for_each(pos, &conf_head) {
 610                 item = list_entry(pos, struct arg_item, list);
 611                 if (token_matches_item(tok->buf, item, tok_len)) {
 612                         char *tok_buf = strbuf_detach(tok, NULL);
 613                         if (conf)
 614                                 *conf = &item->conf;
 615                         strbuf_addstr(tok, token_from_item(item, tok_buf));
 616                         free(tok_buf);
 617                         break;
 618                 }
 619         }
 620 }
 621
 622 static void add_trailer_item(struct list_head *head, char *tok, char *val)
 623 {
 624         struct trailer_item *new = xcalloc(sizeof(*new), 1);
 625         new->token = tok;
 626         new->value = val;
 627         list_add_tail(&new->list, head);
 628 }
 629
 630 static void add_arg_item(struct list_head *arg_head, char *tok, char *val,
 631                          const struct conf_info *conf)
 632 {
 633         struct arg_item *new = xcalloc(sizeof(*new), 1);
 634         new->token = tok;
 635         new->value = val;
 636         duplicate_conf(&new->conf, conf);
 637         list_add_tail(&new->list, arg_head);
 638 }
 639
 640 static void process_command_line_args(struct list_head *arg_head,
 641                                       struct string_list *trailers)
 642 {
 643         struct string_list_item *tr;
 644         struct arg_item *item;
 645         struct strbuf tok = STRBUF_INIT;
 646         struct strbuf val = STRBUF_INIT;
 647         const struct conf_info *conf;
 648         struct list_head *pos;
 649
 650         /*
 651          * In command-line arguments, '=' is accepted (in addition to the
 652          * separators that are defined).
 653          */
 654         char *cl_separators = xstrfmt("=%s", separators);
 655
 656         /* Add an arg item for each configured trailer with a command */
 657         list_for_each(pos, &conf_head) {
 658                 item = list_entry(pos, struct arg_item, list);
 659                 if (item->conf.command)
 660                         add_arg_item(arg_head,
 661                                      xstrdup(token_from_item(item, NULL)),
 662                                      xstrdup(""),
 663                                      &item->conf);
 664         }
 665
 666         /* Add an arg item for each trailer on the command line */
 667         for_each_string_list_item(tr, trailers) {
 668                 int separator_pos = find_separator(tr->string, cl_separators);
 669                 if (separator_pos == 0) {
 670                         struct strbuf sb = STRBUF_INIT;
 671                         strbuf_addstr(&sb, tr->string);
 672                         strbuf_trim(&sb);
 673                         error(_("empty trailer token in trailer '%.*s'"),
 674                               (int) sb.len, sb.buf);
 675                         strbuf_release(&sb);
 676                 } else {
 677                         parse_trailer(&tok, &val, &conf, tr->string,
 678                                       separator_pos);
 679                         add_arg_item(arg_head,
 680                                      strbuf_detach(&tok, NULL),
 681                                      strbuf_detach(&val, NULL),
 682                                      conf);
 683                 }
 684         }
 685
 686         free(cl_separators);
 687 }
 688
 689 static struct strbuf **read_input_file(const char *file)
 690 {
 691         struct strbuf **lines;
 692         struct strbuf sb = STRBUF_INIT;
 693
 694         if (file) {
 695                 if (strbuf_read_file(&sb, file, 0) < 0)
 696                         die_errno(_("could not read input file '%s'"), file);
 697         } else {
 698                 if (strbuf_read(&sb, fileno(stdin), 0) < 0)
 699                         die_errno(_("could not read from stdin"));
 700         }
 701
 702         lines = strbuf_split(&sb, '\n');
 703
 704         strbuf_release(&sb);
 705
 706         return lines;
 707 }
 708
 709 /*
 710  * Return the (0 based) index of the start of the patch or the line
 711  * count if there is no patch in the message.
 712  */
 713 static int find_patch_start(struct strbuf **lines, int count)
 714 {
 715         int i;
 716
 717         /* Get the start of the patch part if any */
 718         for (i = 0; i < count; i++) {
 719                 if (starts_with(lines[i]->buf, "---"))
 720                         return i;
 721         }
 722
 723         return count;
 724 }
 725
 726 /*
 727  * Return the (0 based) index of the first trailer line or count if
 728  * there are no trailers. Trailers are searched only in the lines from
 729  * index (count - 1) down to index 0.
 730  */
 731 static int find_trailer_start(struct strbuf **lines, int count)
 732 {
 733         int start, end_of_title, only_spaces = 1;
 734         int recognized_prefix = 0, trailer_lines = 0, non_trailer_lines = 0;
 735
 736         /* The first paragraph is the title and cannot be trailers */
 737         for (start = 0; start < count; start++) {
 738                 if (lines[start]->buf[0] == comment_line_char)
 739                         continue;
 740                 if (contains_only_spaces(lines[start]->buf))
 741                         break;
 742         }
 743         end_of_title = start;
 744
 745         /*
 746          * Get the start of the trailers by looking starting from the end for a
 747          * blank line before a set of non-blank lines that (i) are all
 748          * trailers, or (ii) contains at least one Git-generated trailer and
 749          * consists of at least 25% trailers.
 750          */
 751         for (start = count - 1; start >= end_of_title; start--) {
 752                 const char **p;
 753                 int separator_pos;
 754
 755                 if (lines[start]->buf[0] == comment_line_char)
 756                         continue;
 757                 if (contains_only_spaces(lines[start]->buf)) {
 758                         if (only_spaces)
 759                                 continue;
 760                         if (recognized_prefix &&
 761                             trailer_lines * 3 >= non_trailer_lines)
 762                                 return start + 1;
 763                         if (trailer_lines && !non_trailer_lines)
 764                                 return start + 1;
 765                         return count;
 766                 }
 767                 only_spaces = 0;
 768
 769                 for (p = git_generated_prefixes; *p; p++) {
 770                         if (starts_with(lines[start]->buf, *p)) {
 771                                 trailer_lines++;
 772                                 recognized_prefix = 1;
 773                                 goto continue_outer_loop;
 774                         }
 775                 }
 776
 777                 separator_pos = find_separator(lines[start]->buf);
 778                 if (separator_pos >= 1) {
 779                         struct list_head *pos;
 780
 781                         trailer_lines++;
 782                         if (recognized_prefix)
 783                                 continue;
 784                         list_for_each(pos, &conf_head) {
 785                                 struct arg_item *item;
 786                                 item = list_entry(pos, struct arg_item, list);
 787                                 if (token_matches_item(lines[start]->buf, item,
 788                                                        separator_pos)) {
 789                                         recognized_prefix = 1;
 790                                         break;
 791                                 }
 792                         }
 793                 } else
 794                         non_trailer_lines++;
 795 continue_outer_loop:
 796                 ;
 797         }
 798
 799         return count;
 800 }
 801
 802 /* Get the index of the end of the trailers */
 803 static int find_trailer_end(struct strbuf **lines, int patch_start)
 804 {
 805         struct strbuf sb = STRBUF_INIT;
 806         int i, ignore_bytes;
 807
 808         for (i = 0; i < patch_start; i++)
 809                 strbuf_addbuf(&sb, lines[i]);
 810         ignore_bytes = ignore_non_trailer(&sb);
 811         strbuf_release(&sb);
 812         for (i = patch_start - 1; i >= 0 && ignore_bytes > 0; i--)
 813                 ignore_bytes -= lines[i]->len;
 814
 815         return i + 1;
 816 }
 817
 818 static int has_blank_line_before(struct strbuf **lines, int start)
 819 {
 820         for (;start >= 0; start--) {
 821                 if (lines[start]->buf[0] == comment_line_char)
 822                         continue;
 823                 return contains_only_spaces(lines[start]->buf);
 824         }
 825         return 0;
 826 }
 827
 828 static void print_lines(FILE *outfile, struct strbuf **lines, int start, int end)
 829 {
 830         int i;
 831         for (i = start; lines[i] && i < end; i++)
 832                 fprintf(outfile, "%s", lines[i]->buf);
 833 }
 834
 835 static int process_input_file(FILE *outfile,
 836                               struct strbuf **lines,
 837                               struct list_head *head)
 838 {
 839         int count = 0;
 840         int patch_start, trailer_start, trailer_end, i;
 841         struct strbuf tok = STRBUF_INIT;
 842         struct strbuf val = STRBUF_INIT;
 843
 844         /* Get the line count */
 845         while (lines[count])
 846                 count++;
 847
 848         patch_start = find_patch_start(lines, count);
 849         trailer_end = find_trailer_end(lines, patch_start);
 850         trailer_start = find_trailer_start(lines, trailer_end);
 851
 852         /* Print lines before the trailers as is */
 853         print_lines(outfile, lines, 0, trailer_start);
 854
 855         if (!has_blank_line_before(lines, trailer_start - 1))
 856                 fprintf(outfile, "\n");
 857
 858         /* Parse trailer lines */
 859         for (i = trailer_start; i < trailer_end; i++) {
 860                 int separator_pos;
 861                 if (lines[i]->buf[0] == comment_line_char)
 862                         continue;
 863                 separator_pos = find_separator(lines[i]->buf, separators);
 864                 if (separator_pos >= 1) {
 865                         parse_trailer(&tok, &val, NULL, lines[i]->buf,
 866                                       separator_pos);
 867                         add_trailer_item(head,
 868                                          strbuf_detach(&tok, NULL),
 869                                          strbuf_detach(&val, NULL));
 870                 } else {
 871                         strbuf_addbuf(&val, lines[i]);
 872                         strbuf_strip_suffix(&val, "\n");
 873                         add_trailer_item(head,
 874                                          NULL,
 875                                          strbuf_detach(&val, NULL));
 876                 }
 877         }
 878
 879         return trailer_end;
 880 }
 881
 882 static void free_all(struct list_head *head)
 883 {
 884         struct list_head *pos, *p;
 885         list_for_each_safe(pos, p, head) {
 886                 list_del(pos);
 887                 free_trailer_item(list_entry(pos, struct trailer_item, list));
 888         }
 889 }
 890
 891 static struct tempfile trailers_tempfile;
 892
 893 static FILE *create_in_place_tempfile(const char *file)
 894 {
 895         struct stat st;
 896         struct strbuf template = STRBUF_INIT;
 897         const char *tail;
 898         FILE *outfile;
 899
 900         if (stat(file, &st))
 901                 die_errno(_("could not stat %s"), file);
 902         if (!S_ISREG(st.st_mode))
 903                 die(_("file %s is not a regular file"), file);
 904         if (!(st.st_mode & S_IWUSR))
 905                 die(_("file %s is not writable by user"), file);
 906
 907         /* Create temporary file in the same directory as the original */
 908         tail = strrchr(file, '/');
 909         if (tail != NULL)
 910                 strbuf_add(&template, file, tail - file + 1);
 911         strbuf_addstr(&template, "git-interpret-trailers-XXXXXX");
 912
 913         xmks_tempfile_m(&trailers_tempfile, template.buf, st.st_mode);
 914         strbuf_release(&template);
 915         outfile = fdopen_tempfile(&trailers_tempfile, "w");
 916         if (!outfile)
 917                 die_errno(_("could not open temporary file"));
 918
 919         return outfile;
 920 }
 921
 922 void process_trailers(const char *file, int in_place, int trim_empty, struct string_list *trailers)
 923 {
 924         LIST_HEAD(head);
 925         LIST_HEAD(arg_head);
 926         struct strbuf **lines;
 927         int trailer_end;
 928         FILE *outfile = stdout;
 929
 930         /* Default config must be setup first */
 931         git_config(git_trailer_default_config, NULL);
 932         git_config(git_trailer_config, NULL);
 933
 934         lines = read_input_file(file);
 935
 936         if (in_place)
 937                 outfile = create_in_place_tempfile(file);
 938
 939         /* Print the lines before the trailers */
 940         trailer_end = process_input_file(outfile, lines, &head);
 941
 942         process_command_line_args(&arg_head, trailers);
 943
 944         process_trailers_lists(&head, &arg_head);
 945
 946         print_all(outfile, &head, trim_empty);
 947
 948         free_all(&head);
 949
 950         /* Print the lines after the trailers as is */
 951         print_lines(outfile, lines, trailer_end, INT_MAX);
 952
 953         if (in_place)
 954                 if (rename_tempfile(&trailers_tempfile, file))
 955                         die_errno(_("could not rename temporary file to %s"), file);
 956
 957         strbuf_list_free(lines);
 958 }