/src/git/trailer.c

Source
#define USE_THE_REPOSITORY_VARIABLE

#include "git-compat-util.h"
#include "config.h"
#include "environment.h"
#include "gettext.h"
#include "string-list.h"
#include "run-command.h"
#include "commit.h"
#include "strvec.h"
#include "trailer.h"
#include "list.h"
#include "tempfile.h"

/*
 * Copyright (c) 2013, 2014 Christian Couder <chriscool@tuxfamily.org>
 */

struct trailer_block {
  /*
   * True if there is a blank line before the location pointed to by
   * "start".
   */
  int blank_line_before_trailer;

  /*
   * The locations of the start and end positions of the trailer block
   * found, as offsets from the beginning of the source text from which
   * this trailer block was parsed. If no trailer block is found, these
   * are both set to 0.
   */
  size_t start, end;

  /*
   * Array of trailers found.
   */
  char **trailers;
  size_t trailer_nr;
};

struct conf_info {
  char *name;
  char *key;
  char *command;
  char *cmd;
  enum trailer_where where;
  enum trailer_if_exists if_exists;
  enum trailer_if_missing if_missing;
};

static struct conf_info default_conf_info;

struct trailer_item {
  struct list_head list;
  /*
   * If this is not a trailer line, the line is stored in value
   * (excluding the terminating newline) and token is NULL.
   */
  char *token;
  char *value;
};

struct arg_item {
  struct list_head list;
  char *token;
  char *value;
  struct conf_info conf;
};

static LIST_HEAD(conf_head);

static const char *separators = ":";

static int configured;

#define TRAILER_ARG_STRING "$ARG"

static const char *git_generated_prefixes[] = {
  "Signed-off-by: ",
  "(cherry picked from commit ",
  NULL
};

/* Iterate over the elements of the list. */
#define list_for_each_dir(pos, head, is_reverse) \
  for (pos = is_reverse ? (head)->prev : (head)->next; \
    pos != (head); \
    pos = is_reverse ? pos->prev : pos->next)

static int after_or_end(enum trailer_where where)
{
  return (where == WHERE_AFTER) || (where == WHERE_END);
}

/*
 * Return the length of the string not including any final
 * punctuation. E.g., the input "Signed-off-by:" would return
 * 13, stripping the trailing punctuation but retaining
 * internal punctuation.
 */
static size_t token_len_without_separator(const char *token, size_t len)
{
  while (len > 0 && !isalnum(token[len - 1]))
    len--;
  return len;
}

static int same_token(struct trailer_item *a, struct arg_item *b)
{
  size_t a_len, b_len, min_len;

  if (!a->token)
    return 0;

  a_len = token_len_without_separator(a->token, strlen(a->token));
  b_len = token_len_without_separator(b->token, strlen(b->token));
  min_len = (a_len > b_len) ? b_len : a_len;

  return !strncasecmp(a->token, b->token, min_len);
}

static int same_value(struct trailer_item *a, struct arg_item *b)
{
  return !strcasecmp(a->value, b->value);
}

static int same_trailer(struct trailer_item *a, struct arg_item *b)
{
  return same_token(a, b) && same_value(a, b);
}

static inline int is_blank_line(const char *str)
{
  const char *s = str;
  while (*s && *s != '\n' && isspace(*s))
    s++;
  return !*s || *s == '\n';
}

static inline void strbuf_replace(struct strbuf *sb, const char *a, const char *b)
{
  const char *ptr = strstr(sb->buf, a);
  if (ptr)
    strbuf_splice(sb, ptr - sb->buf, strlen(a), b, strlen(b));
}

static void free_trailer_item(struct trailer_item *item)
{
  free(item->token);
  free(item->value);
  free(item);
}

static void free_arg_item(struct arg_item *item)
{
  free(item->conf.name);
  free(item->conf.key);
  free(item->conf.command);
  free(item->conf.cmd);
  free(item->token);
  free(item->value);
  free(item);
}

static char last_non_space_char(const char *s)
{
  int i;
  for (i = strlen(s) - 1; i >= 0; i--)
    if (!isspace(s[i]))
      return s[i];
  return '\0';
}

static struct trailer_item *trailer_from_arg(struct arg_item *arg_tok)
{
  struct trailer_item *new_item = xcalloc(1, sizeof(*new_item));
  new_item->token = arg_tok->token;
  new_item->value = arg_tok->value;
  arg_tok->token = arg_tok->value = NULL;
  free_arg_item(arg_tok);
  return new_item;
}

static void add_arg_to_input_list(struct trailer_item *on_tok,
          struct arg_item *arg_tok)
{
  int aoe = after_or_end(arg_tok->conf.where);
  struct trailer_item *to_add = trailer_from_arg(arg_tok);
  if (aoe)
    list_add(&to_add->list, &on_tok->list);
  else
    list_add_tail(&to_add->list, &on_tok->list);
}

static int check_if_different(struct trailer_item *in_tok,
            struct arg_item *arg_tok,
            int check_all,
            struct list_head *head)
{
  enum trailer_where where = arg_tok->conf.where;
  struct list_head *next_head;
  do {
    if (same_trailer(in_tok, arg_tok))
      return 0;
    /*
     * if we want to add a trailer after another one,
     * we have to check those before this one
     */
    next_head = after_or_end(where) ? in_tok->list.prev
            : in_tok->list.next;
    if (next_head == head)
      break;
    in_tok = list_entry(next_head, struct trailer_item, list);
  } while (check_all);
  return 1;
}

static char *apply_command(struct conf_info *conf, const char *arg)
{
  struct strbuf cmd = STRBUF_INIT;
  struct strbuf buf = STRBUF_INIT;
  struct child_process cp = CHILD_PROCESS_INIT;
  char *result;

  if (conf->cmd) {
    strbuf_addstr(&cmd, conf->cmd);
    strvec_push(&cp.args, cmd.buf);
    if (arg)
      strvec_push(&cp.args, arg);
  } else if (conf->command) {
    strbuf_addstr(&cmd, conf->command);
    if (arg)
      strbuf_replace(&cmd, TRAILER_ARG_STRING, arg);
    strvec_push(&cp.args, cmd.buf);
  }
  strvec_pushv(&cp.env, (const char **)local_repo_env);
  cp.no_stdin = 1;
  cp.use_shell = 1;

  if (capture_command(&cp, &buf, 1024)) {
    error(_("running trailer command '%s' failed"), cmd.buf);
    strbuf_release(&buf);
    result = xstrdup("");
  } else {
    strbuf_trim(&buf);
    result = strbuf_detach(&buf, NULL);
  }

  strbuf_release(&cmd);
  return result;
}

static void apply_item_command(struct trailer_item *in_tok, struct arg_item *arg_tok)
{
  if (arg_tok->conf.command || arg_tok->conf.cmd) {
    char *value_to_free = NULL;
    char *arg;

    if (arg_tok->value && arg_tok->value[0]) {
      arg = arg_tok->value;
    } else {
      if (in_tok && in_tok->value)
        arg = xstrdup(in_tok->value);
      else
        arg = xstrdup("");
      value_to_free = arg_tok->value;
    }

    arg_tok->value = apply_command(&arg_tok->conf, arg);

    free(value_to_free);
    free(arg);
  }
}

static void apply_arg_if_exists(struct trailer_item *in_tok,
        struct arg_item *arg_tok,
        struct trailer_item *on_tok,
        struct list_head *head)
{
  switch (arg_tok->conf.if_exists) {
  case EXISTS_DO_NOTHING:
    free_arg_item(arg_tok);
    break;
  case EXISTS_REPLACE:
    apply_item_command(in_tok, arg_tok);
    add_arg_to_input_list(on_tok, arg_tok);
    list_del(&in_tok->list);
    free_trailer_item(in_tok);
    break;
  case EXISTS_ADD:
    apply_item_command(in_tok, arg_tok);
    add_arg_to_input_list(on_tok, arg_tok);
    break;
  case EXISTS_ADD_IF_DIFFERENT:
    apply_item_command(in_tok, arg_tok);
    if (check_if_different(in_tok, arg_tok, 1, head))
      add_arg_to_input_list(on_tok, arg_tok);
    else
      free_arg_item(arg_tok);
    break;
  case EXISTS_ADD_IF_DIFFERENT_NEIGHBOR:
    apply_item_command(in_tok, arg_tok);
    if (check_if_different(on_tok, arg_tok, 0, head))
      add_arg_to_input_list(on_tok, arg_tok);
    else
      free_arg_item(arg_tok);
    break;
  default:
    BUG("trailer.c: unhandled value %d",
        arg_tok->conf.if_exists);
  }
}

static void apply_arg_if_missing(struct list_head *head,
         struct arg_item *arg_tok)
{
  enum trailer_where where;
  struct trailer_item *to_add;

  switch (arg_tok->conf.if_missing) {
  case MISSING_DO_NOTHING:
    free_arg_item(arg_tok);
    break;
  case MISSING_ADD:
    where = arg_tok->conf.where;
    apply_item_command(NULL, arg_tok);
    to_add = trailer_from_arg(arg_tok);
    if (after_or_end(where))
      list_add_tail(&to_add->list, head);
    else
      list_add(&to_add->list, head);
    break;
  default:
    BUG("trailer.c: unhandled value %d",
        arg_tok->conf.if_missing);
  }
}

static int find_same_and_apply_arg(struct list_head *head,
           struct arg_item *arg_tok)
{
  struct list_head *pos;
  struct trailer_item *in_tok;
  struct trailer_item *on_tok;

  enum trailer_where where = arg_tok->conf.where;
  int middle = (where == WHERE_AFTER) || (where == WHERE_BEFORE);
  int backwards = after_or_end(where);
  struct trailer_item *start_tok;

  if (list_empty(head))
    return 0;

  start_tok = list_entry(backwards ? head->prev : head->next,
             struct trailer_item,
             list);

  list_for_each_dir(pos, head, backwards) {
    in_tok = list_entry(pos, struct trailer_item, list);
    if (!same_token(in_tok, arg_tok))
      continue;
    on_tok = middle ? in_tok : start_tok;
    apply_arg_if_exists(in_tok, arg_tok, on_tok, head);
    return 1;
  }
  return 0;
}

void process_trailers_lists(struct list_head *head,
          struct list_head *arg_head)
{
  struct list_head *pos, *p;
  struct arg_item *arg_tok;

  list_for_each_safe(pos, p, arg_head) {
    int applied = 0;
    arg_tok = list_entry(pos, struct arg_item, list);

    list_del(pos);

    applied = find_same_and_apply_arg(head, arg_tok);

    if (!applied)
      apply_arg_if_missing(head, arg_tok);
  }
}

int trailer_set_where(enum trailer_where *item, const char *value)
{
  if (!value)
    *item = WHERE_DEFAULT;
  else if (!strcasecmp("after", value))
    *item = WHERE_AFTER;
  else if (!strcasecmp("before", value))
    *item = WHERE_BEFORE;
  else if (!strcasecmp("end", value))
    *item = WHERE_END;
  else if (!strcasecmp("start", value))
    *item = WHERE_START;
  else
    return -1;
  return 0;
}

int trailer_set_if_exists(enum trailer_if_exists *item, const char *value)
{
  if (!value)
    *item = EXISTS_DEFAULT;
  else if (!strcasecmp("addIfDifferent", value))
    *item = EXISTS_ADD_IF_DIFFERENT;
  else if (!strcasecmp("addIfDifferentNeighbor", value))
    *item = EXISTS_ADD_IF_DIFFERENT_NEIGHBOR;
  else if (!strcasecmp("add", value))
    *item = EXISTS_ADD;
  else if (!strcasecmp("replace", value))
    *item = EXISTS_REPLACE;
  else if (!strcasecmp("doNothing", value))
    *item = EXISTS_DO_NOTHING;
  else
    return -1;
  return 0;
}

int trailer_set_if_missing(enum trailer_if_missing *item, const char *value)
{
  if (!value)
    *item = MISSING_DEFAULT;
  else if (!strcasecmp("doNothing", value))
    *item = MISSING_DO_NOTHING;
  else if (!strcasecmp("add", value))
    *item = MISSING_ADD;
  else
    return -1;
  return 0;
}

static void duplicate_conf(struct conf_info *dst, const struct conf_info *src)
{
  *dst = *src;
  dst->name = xstrdup_or_null(src->name);
  dst->key = xstrdup_or_null(src->key);
  dst->command = xstrdup_or_null(src->command);
  dst->cmd = xstrdup_or_null(src->cmd);
}

static struct arg_item *get_conf_item(const char *name)
{
  struct list_head *pos;
  struct arg_item *item;

  /* Look up item with same name */
  list_for_each(pos, &conf_head) {
    item = list_entry(pos, struct arg_item, list);
    if (!strcasecmp(item->conf.name, name))
      return item;
  }

  /* Item does not already exists, create it */
  CALLOC_ARRAY(item, 1);
  duplicate_conf(&item->conf, &default_conf_info);
  item->conf.name = xstrdup(name);

  list_add_tail(&item->list, &conf_head);

  return item;
}

enum trailer_info_type { TRAILER_KEY, TRAILER_COMMAND, TRAILER_CMD,
      TRAILER_WHERE, TRAILER_IF_EXISTS, TRAILER_IF_MISSING };

static struct {
  const char *name;
  enum trailer_info_type type;
} trailer_config_items[] = {
  { "key", TRAILER_KEY },
  { "command", TRAILER_COMMAND },
  { "cmd", TRAILER_CMD },
  { "where", TRAILER_WHERE },
  { "ifexists", TRAILER_IF_EXISTS },
  { "ifmissing", TRAILER_IF_MISSING }
};

static int git_trailer_default_config(const char *conf_key, const char *value,
              const struct config_context *ctx UNUSED,
              void *cb UNUSED)
{
  const char *trailer_item, *variable_name;

  if (!skip_prefix(conf_key, "trailer.", &trailer_item))
    return 0;

  variable_name = strrchr(trailer_item, '.');
  if (!variable_name) {
    if (!strcmp(trailer_item, "where")) {
      if (trailer_set_where(&default_conf_info.where,
                value) < 0)
        warning(_("unknown value '%s' for key '%s'"),
          value, conf_key);
    } else if (!strcmp(trailer_item, "ifexists")) {
      if (trailer_set_if_exists(&default_conf_info.if_exists,
              value) < 0)
        warning(_("unknown value '%s' for key '%s'"),
          value, conf_key);
    } else if (!strcmp(trailer_item, "ifmissing")) {
      if (trailer_set_if_missing(&default_conf_info.if_missing,
               value) < 0)
        warning(_("unknown value '%s' for key '%s'"),
          value, conf_key);
    } else if (!strcmp(trailer_item, "separators")) {
      if (!value)
        return config_error_nonbool(conf_key);
      separators = xstrdup(value);
    }
  }
  return 0;
}

static int git_trailer_config(const char *conf_key, const char *value,
            const struct config_context *ctx UNUSED,
            void *cb UNUSED)
{
  const char *trailer_item, *variable_name;
  struct arg_item *item;
  struct conf_info *conf;
  char *name = NULL;
  enum trailer_info_type type;

  if (!skip_prefix(conf_key, "trailer.", &trailer_item))
    return 0;

  variable_name = strrchr(trailer_item, '.');
  if (!variable_name)
    return 0;

  variable_name++;
  for (size_t i = 0; i < ARRAY_SIZE(trailer_config_items); i++) {
    if (strcmp(trailer_config_items[i].name, variable_name))
      continue;
    name = xstrndup(trailer_item,  variable_name - trailer_item - 1);
    type = trailer_config_items[i].type;
    break;
  }

  if (!name)
    return 0;

  item = get_conf_item(name);
  conf = &item->conf;
  free(name);

  switch (type) {
  case TRAILER_KEY:
    if (conf->key)
      warning(_("more than one %s"), conf_key);
    if (!value)
      return config_error_nonbool(conf_key);
    conf->key = xstrdup(value);
    break;
  case TRAILER_COMMAND:
    if (conf->command)
      warning(_("more than one %s"), conf_key);
    if (!value)
      return config_error_nonbool(conf_key);
    conf->command = xstrdup(value);
    break;
  case TRAILER_CMD:
    if (conf->cmd)
      warning(_("more than one %s"), conf_key);
    if (!value)
      return config_error_nonbool(conf_key);
    conf->cmd = xstrdup(value);
    break;
  case TRAILER_WHERE:
    if (trailer_set_where(&conf->where, value))
      warning(_("unknown value '%s' for key '%s'"), value, conf_key);
    break;
  case TRAILER_IF_EXISTS:
    if (trailer_set_if_exists(&conf->if_exists, value))
      warning(_("unknown value '%s' for key '%s'"), value, conf_key);
    break;
  case TRAILER_IF_MISSING:
    if (trailer_set_if_missing(&conf->if_missing, value))
      warning(_("unknown value '%s' for key '%s'"), value, conf_key);
    break;
  default:
    BUG("trailer.c: unhandled type %d", type);
  }
  return 0;
}

void trailer_config_init(void)
{
  if (configured)
    return;

  /* Default config must be setup first */
  default_conf_info.where = WHERE_END;
  default_conf_info.if_exists = EXISTS_ADD_IF_DIFFERENT_NEIGHBOR;
  default_conf_info.if_missing = MISSING_ADD;
  repo_config(the_repository, git_trailer_default_config, NULL);
  repo_config(the_repository, git_trailer_config, NULL);
  configured = 1;
}

static const char *token_from_item(struct arg_item *item, char *tok)
{
  if (item->conf.key)
    return item->conf.key;
  if (tok)
    return tok;
  return item->conf.name;
}

static int token_matches_item(const char *tok, struct arg_item *item, size_t tok_len)
{
  if (!strncasecmp(tok, item->conf.name, tok_len))
    return 1;
  return item->conf.key ? !strncasecmp(tok, item->conf.key, tok_len) : 0;
}

/*
 * If the given line is of the form
 * "<token><optional whitespace><separator>..." or "<separator>...", return the
 * location of the separator. Otherwise, return -1.  The optional whitespace
 * is allowed there primarily to allow things like "Bug #43" where <token> is
 * "Bug" and <separator> is "#".
 *
 * The separator-starts-line case (in which this function returns 0) is
 * distinguished from the non-well-formed-line case (in which this function
 * returns -1) because some callers of this function need such a distinction.
 */
static ssize_t find_separator(const char *line, const char *separators)
{
  int whitespace_found = 0;
  const char *c;
  for (c = line; *c; c++) {
    if (strchr(separators, *c)) {
      /* avoid accidental URL matches */
      if (!whitespace_found && starts_with(c, "://"))
        return -1;
      return c - line;
    }
    if (!whitespace_found && (isalnum(*c) || *c == '-'))
      continue;
    if (c != line && (*c == ' ' || *c == '\t')) {
      whitespace_found = 1;
      continue;
    }
    break;
  }
  return -1;
}

/*
 * Obtain the token, value, and conf from the given trailer.
 *
 * separator_pos must not be 0, since the token cannot be an empty string.
 *
 * If separator_pos is -1, interpret the whole trailer as a token.
 */
static void parse_trailer(struct strbuf *tok, struct strbuf *val,
       const struct conf_info **conf, const char *trailer,
       ssize_t separator_pos)
{
  struct arg_item *item;
  size_t tok_len;
  struct list_head *pos;

  if (separator_pos != -1) {
    strbuf_add(tok, trailer, separator_pos);
    strbuf_trim(tok);
    strbuf_addstr(val, trailer + separator_pos + 1);
    strbuf_trim(val);
  } else {
    strbuf_addstr(tok, trailer);
    strbuf_trim(tok);
  }

  /* Lookup if the token matches something in the config */
  tok_len = token_len_without_separator(tok->buf, tok->len);
  if (conf)
    *conf = &default_conf_info;
  list_for_each(pos, &conf_head) {
    item = list_entry(pos, struct arg_item, list);
    if (token_matches_item(tok->buf, item, tok_len)) {
      char *tok_buf = strbuf_detach(tok, NULL);
      if (conf)
        *conf = &item->conf;
      strbuf_addstr(tok, token_from_item(item, tok_buf));
      free(tok_buf);
      break;
    }
  }
}

static struct trailer_item *add_trailer_item(struct list_head *head, char *tok,
               char *val)
{
  struct trailer_item *new_item = xcalloc(1, sizeof(*new_item));
  new_item->token = tok;
  new_item->value = val;
  list_add_tail(&new_item->list, head);
  return new_item;
}

static void add_arg_item(struct list_head *arg_head, char *tok, char *val,
       const struct conf_info *conf,
       const struct new_trailer_item *new_trailer_item)
{
  struct arg_item *new_item = xcalloc(1, sizeof(*new_item));
  new_item->token = tok;
  new_item->value = val;
  duplicate_conf(&new_item->conf, conf);
  if (new_trailer_item) {
    if (new_trailer_item->where != WHERE_DEFAULT)
      new_item->conf.where = new_trailer_item->where;
    if (new_trailer_item->if_exists != EXISTS_DEFAULT)
      new_item->conf.if_exists = new_trailer_item->if_exists;
    if (new_trailer_item->if_missing != MISSING_DEFAULT)
      new_item->conf.if_missing = new_trailer_item->if_missing;
  }
  list_add_tail(&new_item->list, arg_head);
}

void parse_trailers_from_config(struct list_head *config_head)
{
  struct arg_item *item;
  struct list_head *pos;

  /* Add an arg item for each configured trailer with a command */
  list_for_each(pos, &conf_head) {
    item = list_entry(pos, struct arg_item, list);
    if (item->conf.command)
      add_arg_item(config_head,
             xstrdup(token_from_item(item, NULL)),
             xstrdup(""),
             &item->conf, NULL);
  }
}

void parse_trailers_from_command_line_args(struct list_head *arg_head,
             struct list_head *new_trailer_head)
{
  struct strbuf tok = STRBUF_INIT;
  struct strbuf val = STRBUF_INIT;
  const struct conf_info *conf;
  struct list_head *pos;

  /*
   * In command-line arguments, '=' is accepted (in addition to the
   * separators that are defined).
   */
  char *cl_separators = xstrfmt("=%s", separators);

  /* Add an arg item for each trailer on the command line */
  list_for_each(pos, new_trailer_head) {
    struct new_trailer_item *tr =
      list_entry(pos, struct new_trailer_item, list);
    ssize_t separator_pos = find_separator(tr->text, cl_separators);

    if (separator_pos == 0) {
      struct strbuf sb = STRBUF_INIT;
      strbuf_addstr(&sb, tr->text);
      strbuf_trim(&sb);
      error(_("empty trailer token in trailer '%.*s'"),
            (int) sb.len, sb.buf);
      strbuf_release(&sb);
    } else {
      parse_trailer(&tok, &val, &conf, tr->text,
              separator_pos);
      add_arg_item(arg_head,
             strbuf_detach(&tok, NULL),
             strbuf_detach(&val, NULL),
             conf, tr);
    }
  }

  free(cl_separators);
}

int validate_trailer_args(const struct strvec *cli_args)
{
  char *cl_separators;
  int ret = 0;

  trailer_config_init();

  cl_separators = xstrfmt("=%s", separators);

  for (size_t i = 0; i < cli_args->nr; i++) {
    const char *txt = cli_args->v[i];
    ssize_t separator_pos;

    if (!*txt) {
      ret = error(_("empty --trailer argument"));
      goto out;
    }
    separator_pos = find_separator(txt, cl_separators);
    if (separator_pos == 0) {
      ret = error(_("invalid trailer '%s': missing key before separator"),
            txt);
      goto out;
    }
  }
out:
  free(cl_separators);
  return ret;
}

static const char *next_line(const char *str)
{
  const char *nl = strchrnul(str, '\n');
  return nl + !!*nl;
}

/*
 * Return the position of the start of the last line. If len is 0, return -1.
 */
static ssize_t last_line(const char *buf, size_t len)
{
  ssize_t i;
  if (len == 0)
    return -1;
  if (len == 1)
    return 0;
  /*
   * Skip the last character (in addition to the null terminator),
   * because if the last character is a newline, it is considered as part
   * of the last line anyway.
   */
  i = len - 2;

  for (; i >= 0; i--) {
    if (buf[i] == '\n')
      return i + 1;
  }
  return 0;
}

/*
 * Find the end of the log message as an offset from the start of the input
 * (where callers of this function are interested in looking for a trailers
 * block in the same input). We have to consider two categories of content that
 * can come at the end of the input which we want to ignore (because they don't
 * belong in the log message):
 *
 * (1) the "patch part" which begins with a "---" divider and has patch
 * information (like the output of git-format-patch), and
 *
 * (2) any trailing comment lines, blank lines like in the output of "git
 * commit -v", or stuff below the "cut" (scissor) line.
 *
 * As a formula, the situation looks like this:
 *
 *     INPUT = LOG MESSAGE + IGNORED
 *
 * where IGNORED can be either of the two categories described above. It may be
 * that there is nothing to ignore. Now it may be the case that the LOG MESSAGE
 * contains a trailer block, but that's not the concern of this function.
 */
static size_t find_end_of_log_message(const char *input, int no_divider)
{
  size_t end;
  const char *s;

  /* Assume the naive end of the input is already what we want. */
  end = strlen(input);

  /* Optionally skip over any patch part ("---" line and below). */
  if (!no_divider) {
    for (s = input; *s; s = next_line(s)) {
      const char *v;

      if (skip_prefix(s, "---", &v) && isspace(*v)) {
        end = s - input;
        break;
      }
    }
  }

  /* Skip over other ignorable bits. */
  return end - ignored_log_message_bytes(input, end);
}

/*
 * Return the position of the first trailer line or len if there are no
 * trailers.
 */
static size_t find_trailer_block_start(const char *buf, size_t len)
{
  const char *s;
  ssize_t end_of_title, l;
  int only_spaces = 1;
  int recognized_prefix = 0, trailer_lines = 0, non_trailer_lines = 0;
  /*
   * Number of possible continuation lines encountered. This will be
   * reset to 0 if we encounter a trailer (since those lines are to be
   * considered continuations of that trailer), and added to
   * non_trailer_lines if we encounter a non-trailer (since those lines
   * are to be considered non-trailers).
   */
  int possible_continuation_lines = 0;

  /* The first paragraph is the title and cannot be trailers */
  for (s = buf; s < buf + len; s = next_line(s)) {
    if (starts_with_mem(s, buf + len - s, comment_line_str))
      continue;
    if (is_blank_line(s))
      break;
  }
  end_of_title = s - buf;

  /*
   * Get the start of the trailers by looking starting from the end for a
   * blank line before a set of non-blank lines that (i) are all
   * trailers, or (ii) contains at least one Git-generated trailer and
   * consists of at least 25% trailers.
   */
  for (l = last_line(buf, len);
       l >= end_of_title;
       l = last_line(buf, l)) {
    const char *bol = buf + l;
    const char **p;
    ssize_t separator_pos;

    if (starts_with_mem(bol, buf + len - bol, comment_line_str)) {
      non_trailer_lines += possible_continuation_lines;
      possible_continuation_lines = 0;
      continue;
    }
    if (is_blank_line(bol)) {
      if (only_spaces)
        continue;
      non_trailer_lines += possible_continuation_lines;
      if (recognized_prefix &&
          trailer_lines * 3 >= non_trailer_lines)
        return next_line(bol) - buf;
      else if (trailer_lines && !non_trailer_lines)
        return next_line(bol) - buf;
      return len;
    }
    only_spaces = 0;

    for (p = git_generated_prefixes; *p; p++) {
      if (starts_with(bol, *p)) {
        trailer_lines++;
        possible_continuation_lines = 0;
        recognized_prefix = 1;
        goto continue_outer_loop;
      }
    }

    separator_pos = find_separator(bol, separators);
    if (separator_pos >= 1 && !isspace(bol[0])) {
      struct list_head *pos;

      trailer_lines++;
      possible_continuation_lines = 0;
      if (recognized_prefix)
        continue;
      list_for_each(pos, &conf_head) {
        struct arg_item *item;
        item = list_entry(pos, struct arg_item, list);
        if (token_matches_item(bol, item,
                   separator_pos)) {
          recognized_prefix = 1;
          break;
        }
      }
    } else if (isspace(bol[0]))
      possible_continuation_lines++;
    else {
      non_trailer_lines++;
      non_trailer_lines += possible_continuation_lines;
      possible_continuation_lines = 0;
    }
continue_outer_loop:
    ;
  }

  return len;
}

static int ends_with_blank_line(const char *buf, size_t len)
{
  ssize_t ll = last_line(buf, len);
  if (ll < 0)
    return 0;
  return is_blank_line(buf + ll);
}

static void unfold_value(struct strbuf *val)
{
  size_t i;
  size_t pos = 0;

  i = 0;
  while (i < val->len) {
    char c = val->buf[i++];
    if (c == '\n') {
      /* Collapse continuation down to a single space. */
      while (i < val->len && isspace(val->buf[i]))
        i++;
      c = ' ';
    }
    val->buf[pos++] = c;
  }
  strbuf_setlen(val, pos);

  /* Empty lines may have left us with whitespace cruft at the edges */
  strbuf_trim(val);
}

static struct trailer_block *trailer_block_new(void)
{
  struct trailer_block *trailer_block = xcalloc(1, sizeof(*trailer_block));
  return trailer_block;
}

static struct trailer_block *trailer_block_get(const struct process_trailer_options *opts,
                 const char *str)
{
  struct trailer_block *trailer_block = trailer_block_new();
  size_t end_of_log_message = 0, trailer_block_start = 0;
  struct strbuf **trailer_lines, **ptr;
  char **trailer_strings = NULL;
  size_t nr = 0, alloc = 0;
  char **last = NULL;

  trailer_config_init();

  end_of_log_message = find_end_of_log_message(str, opts->no_divider);
  trailer_block_start = find_trailer_block_start(str, end_of_log_message);

  trailer_lines = strbuf_split_buf(str + trailer_block_start,
           end_of_log_message - trailer_block_start,
           '\n',
           0);
  for (ptr = trailer_lines; *ptr; ptr++) {
    if (last && isspace((*ptr)->buf[0])) {
      struct strbuf sb = STRBUF_INIT;
      strbuf_attach(&sb, *last, strlen(*last), strlen(*last) + 1);
      strbuf_addbuf(&sb, *ptr);
      *last = strbuf_detach(&sb, NULL);
      continue;
    }
    ALLOC_GROW(trailer_strings, nr + 1, alloc);
    trailer_strings[nr] = strbuf_detach(*ptr, NULL);
    last = find_separator(trailer_strings[nr], separators) >= 1
      ? &trailer_strings[nr]
      : NULL;
    nr++;
  }
  strbuf_list_free(trailer_lines);

  trailer_block->blank_line_before_trailer = ends_with_blank_line(str,
                  trailer_block_start);
  trailer_block->start = trailer_block_start;
  trailer_block->end = end_of_log_message;
  trailer_block->trailers = trailer_strings;
  trailer_block->trailer_nr = nr;

  return trailer_block;
}

/*
 * Parse trailers in "str", populating the trailer_block and "trailer_objects"
 * linked list structure.
 */
struct trailer_block *parse_trailers(const struct process_trailer_options *opts,
             const char *str,
             struct list_head *trailer_objects)
{
  struct trailer_block *trailer_block;
  struct strbuf tok = STRBUF_INIT;
  struct strbuf val = STRBUF_INIT;
  size_t i;

  trailer_block = trailer_block_get(opts, str);

  for (i = 0; i < trailer_block->trailer_nr; i++) {
    int separator_pos;
    char *trailer = trailer_block->trailers[i];
    if (starts_with(trailer, comment_line_str))
      continue;
    separator_pos = find_separator(trailer, separators);
    if (separator_pos >= 1) {
      parse_trailer(&tok, &val, NULL, trailer,
              separator_pos);
      if (opts->unfold)
        unfold_value(&val);
      add_trailer_item(trailer_objects,
           strbuf_detach(&tok, NULL),
           strbuf_detach(&val, NULL));
    } else if (!opts->only_trailers) {
      strbuf_addstr(&val, trailer);
      strbuf_strip_suffix(&val, "\n");
      add_trailer_item(trailer_objects,
           NULL,
           strbuf_detach(&val, NULL));
    }
  }

  return trailer_block;
}

void free_trailers(struct list_head *trailers)
{
  struct list_head *pos, *p;
  list_for_each_safe(pos, p, trailers) {
    list_del(pos);
    free_trailer_item(list_entry(pos, struct trailer_item, list));
  }
}

size_t trailer_block_start(struct trailer_block *trailer_block)
{
  return trailer_block->start;
}

size_t trailer_block_end(struct trailer_block *trailer_block)
{
  return trailer_block->end;
}

int blank_line_before_trailer_block(struct trailer_block *trailer_block)
{
  return trailer_block->blank_line_before_trailer;
}

void trailer_block_release(struct trailer_block *trailer_block)
{
  size_t i;
  for (i = 0; i < trailer_block->trailer_nr; i++)
    free(trailer_block->trailers[i]);
  free(trailer_block->trailers);
  free(trailer_block);
}

void format_trailers(const struct process_trailer_options *opts,
         struct list_head *trailers,
         struct strbuf *out)
{
  struct strbuf tok = STRBUF_INIT;
  struct strbuf val = STRBUF_INIT;
  size_t origlen = out->len;
  struct list_head *pos;
  struct trailer_item *item;

  list_for_each(pos, trailers) {
    item = list_entry(pos, struct trailer_item, list);
    if (item->token) {
      strbuf_reset(&tok);
      strbuf_addstr(&tok, item->token);
      strbuf_reset(&val);
      strbuf_addstr(&val, item->value);

      /*
       * Skip key/value pairs where the value was empty. This
       * can happen from trailers specified without a
       * separator, like `--trailer "Reviewed-by"` (no
       * corresponding value).
       */
      if (opts->trim_empty && !strlen(item->value))
        continue;

      if (!opts->filter || opts->filter(&tok, opts->filter_data)) {
        if (opts->separator && out->len != origlen)
          strbuf_addbuf(out, opts->separator);
        if (!opts->value_only)
          strbuf_addbuf(out, &tok);
        if (!opts->key_only && !opts->value_only) {
          if (opts->key_value_separator)
            strbuf_addbuf(out, opts->key_value_separator);
          else {
            char c = last_non_space_char(tok.buf);
            if (c && !strchr(separators, c))
              strbuf_addf(out, "%c ", separators[0]);
          }
        }
        if (!opts->key_only)
          strbuf_addbuf(out, &val);
        if (!opts->separator)
          strbuf_addch(out, '\n');
      }
    } else if (!opts->only_trailers) {
      if (opts->separator && out->len != origlen) {
        strbuf_addbuf(out, opts->separator);
      }
      strbuf_addstr(out, item->value);
      if (opts->separator)
        strbuf_rtrim(out);
      else
        strbuf_addch(out, '\n');
    }
  }

  strbuf_release(&tok);
  strbuf_release(&val);
}

void format_trailers_from_commit(const struct process_trailer_options *opts,
         const char *msg,
         struct strbuf *out)
{
  LIST_HEAD(trailer_objects);
  struct trailer_block *trailer_block = parse_trailers(opts, msg, &trailer_objects);

  /* If we want the whole block untouched, we can take the fast path. */
  if (!opts->only_trailers && !opts->unfold && !opts->filter &&
      !opts->separator && !opts->key_only && !opts->value_only &&
      !opts->key_value_separator) {
    strbuf_add(out, msg + trailer_block->start,
         trailer_block->end - trailer_block->start);
  } else
    format_trailers(opts, &trailer_objects, out);

  free_trailers(&trailer_objects);
  trailer_block_release(trailer_block);
}

void trailer_iterator_init(struct trailer_iterator *iter, const char *msg)
{
  struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
  strbuf_init(&iter->key, 0);
  strbuf_init(&iter->val, 0);
  opts.no_divider = 1;
  iter->internal.trailer_block = trailer_block_get(&opts, msg);
  iter->internal.cur = 0;
}

int trailer_iterator_advance(struct trailer_iterator *iter)
{
  if (iter->internal.cur < iter->internal.trailer_block->trailer_nr) {
    char *line = iter->internal.trailer_block->trailers[iter->internal.cur++];
    int separator_pos = find_separator(line, separators);

    iter->raw = line;
    strbuf_reset(&iter->key);
    strbuf_reset(&iter->val);
    parse_trailer(&iter->key, &iter->val, NULL,
            line, separator_pos);
    /* Always unfold values during iteration. */
    unfold_value(&iter->val);
    return 1;
  }
  return 0;
}

void trailer_iterator_release(struct trailer_iterator *iter)
{
  trailer_block_release(iter->internal.trailer_block);
  strbuf_release(&iter->val);
  strbuf_release(&iter->key);
}

struct tempfile *trailer_create_in_place_tempfile(const char *file)
{
  struct tempfile *tempfile = NULL;
  struct stat st;
  struct strbuf filename_template = STRBUF_INIT;
  const char *tail;

  if (stat(file, &st)) {
    error_errno(_("could not stat %s"), file);
    return NULL;
  }
  if (!S_ISREG(st.st_mode)) {
    error(_("file %s is not a regular file"), file);
    return NULL;
  }
  if (!(st.st_mode & S_IWUSR)) {
    error(_("file %s is not writable by user"), file);
    return NULL;
  }
  /* Create temporary file in the same directory as the original */
  tail = find_last_dir_sep(file);
  if (tail)
    strbuf_add(&filename_template, file, tail - file + 1);
  strbuf_addstr(&filename_template, "git-interpret-trailers-XXXXXX");

  tempfile = mks_tempfile_m(filename_template.buf, st.st_mode);

  strbuf_release(&filename_template);

  return tempfile;
}

int amend_strbuf_with_trailers(struct strbuf *buf,
        const struct strvec *trailer_args)
{
  struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
  LIST_HEAD(new_trailer_head);
  struct strbuf out = STRBUF_INIT;
  size_t i;
  int ret = 0;

  opts.no_divider = 1;

  for (i = 0; i < trailer_args->nr; i++) {
    const char *text = trailer_args->v[i];
    struct new_trailer_item *item;

    if (!*text) {
      ret = error(_("empty --trailer argument"));
      goto out;
    }
    item = xcalloc(1, sizeof(*item));
    item->text = xstrdup(text);
    list_add_tail(&item->list, &new_trailer_head);
  }

  process_trailers(&opts, &new_trailer_head, buf, &out);

  strbuf_swap(buf, &out);
out:
  strbuf_release(&out);
  free_trailers(&new_trailer_head);

  return ret;
}

static int write_file_in_place(const char *path, const struct strbuf *buf)
{
  struct tempfile *tempfile = trailer_create_in_place_tempfile(path);
  if (!tempfile)
    return -1;

  if (write_in_full(tempfile->fd, buf->buf, buf->len) < 0)
    return error_errno(_("could not write to temporary file"));

  if (rename_tempfile(&tempfile, path))
    return error_errno(_("could not rename temporary file to %s"), path);

  return 0;
}

int amend_file_with_trailers(const char *path,
           const struct strvec *trailer_args)
{
  struct strbuf buf = STRBUF_INIT;
  int ret = 0;

  if (!trailer_args)
    BUG("amend_file_with_trailers called with NULL trailer_args");
  if (!trailer_args->nr)
    return 0;

  if (validate_trailer_args(trailer_args)) {
    ret = -1;
    goto out;
  }
  if (strbuf_read_file(&buf, path, 0) < 0)
    ret = error_errno(_("could not read '%s'"), path);
  else
    amend_strbuf_with_trailers(&buf, trailer_args);

  if (!ret)
    ret = write_file_in_place(path, &buf);
out:
  strbuf_release(&buf);
  return ret;
}

void process_trailers(const struct process_trailer_options *opts,
          struct list_head *new_trailer_head,
          struct strbuf *input, struct strbuf *out)
{
  LIST_HEAD(head);
  struct trailer_block *trailer_block;

  trailer_block = parse_trailers(opts, input->buf, &head);

  /* Print the lines before the trailer block */
  if (!opts->only_trailers)
    strbuf_add(out, input->buf, trailer_block_start(trailer_block));

  if (!opts->only_trailers && !blank_line_before_trailer_block(trailer_block))
    strbuf_addch(out, '\n');

  if (!opts->only_input) {
    LIST_HEAD(config_head);
    LIST_HEAD(arg_head);
    parse_trailers_from_config(&config_head);
    parse_trailers_from_command_line_args(&arg_head, new_trailer_head);
    list_splice(&config_head, &arg_head);
    process_trailers_lists(&head, &arg_head);
  }

  /* Print trailer block. */
  format_trailers(opts, &head, out);
  free_trailers(&head);

  /* Print the lines after the trailer block as is. */
  if (!opts->only_trailers)
    strbuf_add(out, input->buf + trailer_block_end(trailer_block),
         input->len - trailer_block_end(trailer_block));
  trailer_block_release(trailer_block);
}

Coverage Report

Created: 2026-10-17 07:15