/*

 * Builtin "git pull"

 *

 * Based on git-pull.sh by Junio C Hamano

 *

 * Fetch one or more remote refs and merge it/them into the current HEAD.

 */

#include "builtin.h"

#include "advice.h"

#include "config.h"

#include "gettext.h"

#include "hex.h"

#include "merge.h"

#include "object-name.h"

#include "parse-options.h"

#include "run-command.h"

#include "oid-array.h"

#include "remote.h"

#include "dir.h"

#include "path.h"

#include "read-cache-ll.h"

#include "rebase.h"

#include "refs.h"

#include "refspec.h"

#include "submodule.h"

#include "submodule-config.h"

#include "wt-status.h"

#include "commit-reach.h"

#include "sequencer.h"

/**

 * Parses the value of --rebase. If value is a false value, returns

 * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is

 * "merges", returns REBASE_MERGES. If value is a invalid value, dies with

 * a fatal error if fatal is true, otherwise returns REBASE_INVALID.

 */

static enum rebase_type parse_config_rebase(const char *key, const char *value,

    int fatal)

{

  enum rebase_type v = rebase_parse_value(value);

  if (v != REBASE_INVALID)

    return v;

  if (fatal)

    die(_("invalid value for '%s': '%s'"), key, value);

  else

    error(_("invalid value for '%s': '%s'"), key, value);

  return REBASE_INVALID;

}

/**

 * Callback for --rebase, which parses arg with parse_config_rebase().

 */

static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)

{

  enum rebase_type *value = opt->value;

  if (arg)

    *value = parse_config_rebase("--rebase", arg, 0);

  else

    *value = unset ? REBASE_FALSE : REBASE_TRUE;

  return *value == REBASE_INVALID ? -1 : 0;

}

static const char * const pull_usage[] = {

  N_("git pull [<options>] [<repository> [<refspec>...]]"),

  NULL

};

/* Shared options */

static int opt_verbosity;

static const char *opt_progress;

static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;

static int recurse_submodules_cli = RECURSE_SUBMODULES_DEFAULT;

/* Options passed to git-merge or git-rebase */

static enum rebase_type opt_rebase = -1;

static const char *opt_diffstat;

static const char *opt_log;

static const char *opt_signoff;

static const char *opt_squash;

static const char *opt_commit;

static const char *opt_edit;

static const char *cleanup_arg;

static const char *opt_ff;

static const char *opt_verify_signatures;

static const char *opt_verify;

static int opt_autostash = -1;

static int config_autostash;

static int check_trust_level = 1;

static struct strvec opt_strategies = STRVEC_INIT;

static struct strvec opt_strategy_opts = STRVEC_INIT;

static const char *opt_gpg_sign;

static int opt_allow_unrelated_histories;

/* Options passed to git-fetch */

static const char *opt_all;

static const char *opt_append;

static const char *opt_upload_pack;

static int opt_force;

static const char *opt_tags;

static const char *opt_prune;

static const char *max_children;

static int opt_dry_run;

static const char *opt_keep;

static const char *opt_depth;

static const char *opt_unshallow;

static const char *opt_update_shallow;

static const char *opt_refmap;

static const char *opt_ipv4;

static const char *opt_ipv6;

static int opt_show_forced_updates = -1;

static const char *set_upstream;

static struct strvec opt_fetch = STRVEC_INIT;

static struct option pull_options[] = {

  /* Shared options */

  OPT__VERBOSITY(&opt_verbosity),

  OPT_PASSTHRU(0, "progress", &opt_progress, NULL,

    N_("force progress reporting"),

    PARSE_OPT_NOARG),

  OPT_CALLBACK_F(0, "recurse-submodules",

       &recurse_submodules_cli, N_("on-demand"),

       N_("control for recursive fetching of submodules"),

       PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules),

  /* Options passed to git-merge or git-rebase */

  OPT_GROUP(N_("Options related to merging")),

  OPT_CALLBACK_F('r', "rebase", &opt_rebase,

    "(false|true|merges|interactive)",

    N_("incorporate changes by rebasing rather than merging"),

    PARSE_OPT_OPTARG, parse_opt_rebase),

  OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,

    N_("do not show a diffstat at the end of the merge"),

    PARSE_OPT_NOARG | PARSE_OPT_NONEG),

  OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,

    N_("show a diffstat at the end of the merge"),

    PARSE_OPT_NOARG),

  OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,

    N_("(synonym to --stat)"),

    PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),

  OPT_PASSTHRU(0, "log", &opt_log, N_("n"),

    N_("add (at most <n>) entries from shortlog to merge commit message"),

    PARSE_OPT_OPTARG),

  OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,

    N_("add a Signed-off-by trailer"),

    PARSE_OPT_OPTARG),

  OPT_PASSTHRU(0, "squash", &opt_squash, NULL,

    N_("create a single commit instead of doing a merge"),

    PARSE_OPT_NOARG),

  OPT_PASSTHRU(0, "commit", &opt_commit, NULL,

    N_("perform a commit if the merge succeeds (default)"),

    PARSE_OPT_NOARG),

  OPT_PASSTHRU(0, "edit", &opt_edit, NULL,

    N_("edit message before committing"),

    PARSE_OPT_NOARG),

  OPT_CLEANUP(&cleanup_arg),

  OPT_PASSTHRU(0, "ff", &opt_ff, NULL,

    N_("allow fast-forward"),

    PARSE_OPT_NOARG),

  OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,

    N_("abort if fast-forward is not possible"),

    PARSE_OPT_NOARG | PARSE_OPT_NONEG),

  OPT_PASSTHRU(0, "verify", &opt_verify, NULL,

    N_("control use of pre-merge-commit and commit-msg hooks"),

    PARSE_OPT_NOARG),

  OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,

    N_("verify that the named commit has a valid GPG signature"),

    PARSE_OPT_NOARG),

  OPT_BOOL(0, "autostash", &opt_autostash,

    N_("automatically stash/stash pop before and after")),

  OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),

    N_("merge strategy to use"),

    0),

  OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,

    N_("option=value"),

    N_("option for selected merge strategy"),

    0),

  OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),

    N_("GPG sign commit"),

    PARSE_OPT_OPTARG),

  OPT_SET_INT(0, "allow-unrelated-histories",

        &opt_allow_unrelated_histories,

        N_("allow merging unrelated histories"), 1),

  /* Options passed to git-fetch */

  OPT_GROUP(N_("Options related to fetching")),

  OPT_PASSTHRU(0, "all", &opt_all, NULL,

    N_("fetch from all remotes"),

    PARSE_OPT_NOARG),

  OPT_PASSTHRU('a', "append", &opt_append, NULL,

    N_("append to .git/FETCH_HEAD instead of overwriting"),

    PARSE_OPT_NOARG),

  OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),

    N_("path to upload pack on remote end"),

    0),

  OPT__FORCE(&opt_force, N_("force overwrite of local branch"), 0),

  OPT_PASSTHRU('t', "tags", &opt_tags, NULL,

    N_("fetch all tags and associated objects"),

    PARSE_OPT_NOARG),

  OPT_PASSTHRU('p', "prune", &opt_prune, NULL,

    N_("prune remote-tracking branches no longer on remote"),

    PARSE_OPT_NOARG),

  OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),

    N_("number of submodules pulled in parallel"),

    PARSE_OPT_OPTARG),

  OPT_BOOL(0, "dry-run", &opt_dry_run,

    N_("dry run")),

  OPT_PASSTHRU('k', "keep", &opt_keep, NULL,

    N_("keep downloaded pack"),

    PARSE_OPT_NOARG),

  OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),

    N_("deepen history of shallow clone"),

    0),

  OPT_PASSTHRU_ARGV(0, "shallow-since", &opt_fetch, N_("time"),

    N_("deepen history of shallow repository based on time"),

    0),

  OPT_PASSTHRU_ARGV(0, "shallow-exclude", &opt_fetch, N_("revision"),

    N_("deepen history of shallow clone, excluding rev"),

    0),

  OPT_PASSTHRU_ARGV(0, "deepen", &opt_fetch, N_("n"),

    N_("deepen history of shallow clone"),

    0),

  OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,

    N_("convert to a complete repository"),

    PARSE_OPT_NONEG | PARSE_OPT_NOARG),

  OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,

    N_("accept refs that update .git/shallow"),

    PARSE_OPT_NOARG),

  OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),

    N_("specify fetch refmap"),

    PARSE_OPT_NONEG),

  OPT_PASSTHRU_ARGV('o', "server-option", &opt_fetch,

    N_("server-specific"),

    N_("option to transmit"),

    0),

  OPT_PASSTHRU('4',  "ipv4", &opt_ipv4, NULL,

    N_("use IPv4 addresses only"),

    PARSE_OPT_NOARG),

  OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,

    N_("use IPv6 addresses only"),

    PARSE_OPT_NOARG),

  OPT_PASSTHRU_ARGV(0, "negotiation-tip", &opt_fetch, N_("revision"),

    N_("report that we have only objects reachable from this object"),

    0),

  OPT_BOOL(0, "show-forced-updates", &opt_show_forced_updates,

     N_("check for forced-updates on all updated branches")),

  OPT_PASSTHRU(0, "set-upstream", &set_upstream, NULL,

    N_("set upstream for git pull/fetch"),

    PARSE_OPT_NOARG),

  OPT_END()

};

/**

 * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.

 */

static void argv_push_verbosity(struct strvec *arr)

{

  int verbosity;

  for (verbosity = opt_verbosity; verbosity > 0; verbosity--)

    strvec_push(arr, "-v");

  for (verbosity = opt_verbosity; verbosity < 0; verbosity++)

    strvec_push(arr, "-q");

}

/**

 * Pushes "-f" switches into arr to match the opt_force level.

 */

static void argv_push_force(struct strvec *arr)

{

  int force = opt_force;

  while (force-- > 0)

    strvec_push(arr, "-f");

}

/**

 * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv

 */

static void set_reflog_message(int argc, const char **argv)

{

  int i;

  struct strbuf msg = STRBUF_INIT;

  for (i = 0; i < argc; i++) {

    if (i)

      strbuf_addch(&msg, ' ');

    strbuf_addstr(&msg, argv[i]);

  }

  setenv("GIT_REFLOG_ACTION", msg.buf, 0);

  strbuf_release(&msg);

}

/**

 * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If

 * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns

 * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an

 * error.

 */

static const char *config_get_ff(void)

{

  const char *value;

  if (git_config_get_value("pull.ff", &value))

    return NULL;

  switch (git_parse_maybe_bool(value)) {

  case 0:

    return "--no-ff";

  case 1:

    return "--ff";

  }

  if (!strcmp(value, "only"))

    return "--ff-only";

  die(_("invalid value for '%s': '%s'"), "pull.ff", value);

}

/**

 * Returns the default configured value for --rebase. It first looks for the

 * value of "branch.$curr_branch.rebase", where $curr_branch is the current

 * branch, and if HEAD is detached or the configuration key does not exist,

 * looks for the value of "pull.rebase". If both configuration keys do not

 * exist, returns REBASE_FALSE.

 */

static enum rebase_type config_get_rebase(int *rebase_unspecified)

{

  struct branch *curr_branch = branch_get("HEAD");

  const char *value;

  if (curr_branch) {

    char *key = xstrfmt("branch.%s.rebase", curr_branch->name);

    if (!git_config_get_value(key, &value)) {

      enum rebase_type ret = parse_config_rebase(key, value, 1);

      free(key);

      return ret;

    }

    free(key);

  }

  if (!git_config_get_value("pull.rebase", &value))

    return parse_config_rebase("pull.rebase", value, 1);

  *rebase_unspecified = 1;

  return REBASE_FALSE;

}

/**

 * Read config variables.

 */

static int git_pull_config(const char *var, const char *value,

         const struct config_context *ctx, void *cb)

{

  if (!strcmp(var, "rebase.autostash")) {

    config_autostash = git_config_bool(var, value);

    return 0;

  } else if (!strcmp(var, "submodule.recurse")) {

    recurse_submodules = git_config_bool(var, value) ?

      RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;

    return 0;

  } else if (!strcmp(var, "gpg.mintrustlevel")) {

    check_trust_level = 0;

  }

  return git_default_config(var, value, ctx, cb);

}

/**

 * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge

 * into merge_heads.

 */

static void get_merge_heads(struct oid_array *merge_heads)

{

  const char *filename = git_path_fetch_head(the_repository);

  FILE *fp;

  struct strbuf sb = STRBUF_INIT;

  struct object_id oid;

  fp = xfopen(filename, "r");

  while (strbuf_getline_lf(&sb, fp) != EOF) {

    const char *p;

    if (parse_oid_hex(sb.buf, &oid, &p))

      continue;  /* invalid line: does not start with object ID */

    if (starts_with(p, "\tnot-for-merge\t"))

      continue;  /* ref is not-for-merge */

    oid_array_append(merge_heads, &oid);

  }

  fclose(fp);

  strbuf_release(&sb);

}

/**

 * Used by die_no_merge_candidates() as a for_each_remote() callback to

 * retrieve the name of the remote if the repository only has one remote.

 */

static int get_only_remote(struct remote *remote, void *cb_data)

{

  const char **remote_name = cb_data;

  if (*remote_name)

    return -1;

  *remote_name = remote->name;

  return 0;

}

/**

 * Dies with the appropriate reason for why there are no merge candidates:

 *

 * 1. We fetched from a specific remote, and a refspec was given, but it ended

 *    up not fetching anything. This is usually because the user provided a

 *    wildcard refspec which had no matches on the remote end.

 *

 * 2. We fetched from a non-default remote, but didn't specify a branch to

 *    merge. We can't use the configured one because it applies to the default

 *    remote, thus the user must specify the branches to merge.

 *

 * 3. We fetched from the branch's or repo's default remote, but:

 *

 *    a. We are not on a branch, so there will never be a configured branch to

 *       merge with.

 *

 *    b. We are on a branch, but there is no configured branch to merge with.

 *

 * 4. We fetched from the branch's or repo's default remote, but the configured

 *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't

 *    part of the configured fetch refspec.)

 */

static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)

{

  struct branch *curr_branch = branch_get("HEAD");

  const char *remote = curr_branch ? curr_branch->remote_name : NULL;

  if (*refspecs) {

    if (opt_rebase)

      fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));

    else

      fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));

    fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"

          "matches on the remote end."));

  } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {

    fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"

      "a branch. Because this is not the default configured remote\n"

      "for your current branch, you must specify a branch on the command line."),

      repo);

  } else if (!curr_branch) {

    fprintf_ln(stderr, _("You are not currently on a branch."));

    if (opt_rebase)

      fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));

    else

      fprintf_ln(stderr, _("Please specify which branch you want to merge with."));

    fprintf_ln(stderr, _("See git-pull(1) for details."));

    fprintf(stderr, "\n");

    fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));

    fprintf(stderr, "\n");

  } else if (!curr_branch->merge_nr) {

    const char *remote_name = NULL;

    if (for_each_remote(get_only_remote, &remote_name) || !remote_name)

      remote_name = _("<remote>");

    fprintf_ln(stderr, _("There is no tracking information for the current branch."));

    if (opt_rebase)

      fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));

    else

      fprintf_ln(stderr, _("Please specify which branch you want to merge with."));

    fprintf_ln(stderr, _("See git-pull(1) for details."));

    fprintf(stderr, "\n");

    fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));

    fprintf(stderr, "\n");

    fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));

    fprintf(stderr, "\n");

    fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",

        remote_name, _("<branch>"), curr_branch->name);

  } else

    fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"

      "from the remote, but no such ref was fetched."),

      *curr_branch->merge_name);

  exit(1);

}

/**

 * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`

 * as a string and `refspecs` as a null-terminated array of strings. If `repo`

 * is not provided in argv, it is set to NULL.

 */

static void parse_repo_refspecs(int argc, const char **argv, const char **repo,

    const char ***refspecs)

{

  if (argc > 0) {

    *repo = *argv++;

    argc--;

  } else

    *repo = NULL;

  *refspecs = argv;

}

/**

 * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the

 * repository and refspecs to fetch, or NULL if they are not provided.

 */

static int run_fetch(const char *repo, const char **refspecs)

{

  struct child_process cmd = CHILD_PROCESS_INIT;

  strvec_pushl(&cmd.args, "fetch", "--update-head-ok", NULL);

  /* Shared options */

  argv_push_verbosity(&cmd.args);

  if (opt_progress)

    strvec_push(&cmd.args, opt_progress);

  /* Options passed to git-fetch */

  if (opt_all)

    strvec_push(&cmd.args, opt_all);

  if (opt_append)

    strvec_push(&cmd.args, opt_append);

  if (opt_upload_pack)

    strvec_push(&cmd.args, opt_upload_pack);

  argv_push_force(&cmd.args);

  if (opt_tags)

    strvec_push(&cmd.args, opt_tags);

  if (opt_prune)

    strvec_push(&cmd.args, opt_prune);

  if (recurse_submodules_cli != RECURSE_SUBMODULES_DEFAULT)

    switch (recurse_submodules_cli) {

    case RECURSE_SUBMODULES_ON:

      strvec_push(&cmd.args, "--recurse-submodules=on");

      break;

    case RECURSE_SUBMODULES_OFF:

      strvec_push(&cmd.args, "--recurse-submodules=no");

      break;

    case RECURSE_SUBMODULES_ON_DEMAND:

      strvec_push(&cmd.args, "--recurse-submodules=on-demand");

      break;

    default:

      BUG("submodule recursion option not understood");

    }

  if (max_children)

    strvec_push(&cmd.args, max_children);

  if (opt_dry_run)

    strvec_push(&cmd.args, "--dry-run");

  if (opt_keep)

    strvec_push(&cmd.args, opt_keep);

  if (opt_depth)

    strvec_push(&cmd.args, opt_depth);

  if (opt_unshallow)

    strvec_push(&cmd.args, opt_unshallow);

  if (opt_update_shallow)

    strvec_push(&cmd.args, opt_update_shallow);

  if (opt_refmap)

    strvec_push(&cmd.args, opt_refmap);

  if (opt_ipv4)

    strvec_push(&cmd.args, opt_ipv4);

  if (opt_ipv6)

    strvec_push(&cmd.args, opt_ipv6);

  if (opt_show_forced_updates > 0)

    strvec_push(&cmd.args, "--show-forced-updates");

  else if (opt_show_forced_updates == 0)

    strvec_push(&cmd.args, "--no-show-forced-updates");

  if (set_upstream)

    strvec_push(&cmd.args, set_upstream);

  strvec_pushv(&cmd.args, opt_fetch.v);

  if (repo) {

    strvec_push(&cmd.args, repo);

    strvec_pushv(&cmd.args, refspecs);

  } else if (*refspecs)

    BUG("refspecs without repo?");

  cmd.git_cmd = 1;

  cmd.close_object_store = 1;

  return run_command(&cmd);

}

/**

 * "Pulls into void" by branching off merge_head.

 */

static int pull_into_void(const struct object_id *merge_head,

    const struct object_id *curr_head)

{

  if (opt_verify_signatures) {

    struct commit *commit;

    commit = lookup_commit(the_repository, merge_head);

    if (!commit)

      die(_("unable to access commit %s"),

          oid_to_hex(merge_head));

    verify_merge_signature(commit, opt_verbosity,

               check_trust_level);

  }

  /*

   * Two-way merge: we treat the index as based on an empty tree,

   * and try to fast-forward to HEAD. This ensures we will not lose

   * index/worktree changes that the user already made on the unborn

   * branch.

   */

  if (checkout_fast_forward(the_repository,

          the_hash_algo->empty_tree,

          merge_head, 0))

    return 1;

  if (refs_update_ref(get_main_ref_store(the_repository), "initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))

    return 1;

  return 0;

}

static int rebase_submodules(void)

{

  struct child_process cp = CHILD_PROCESS_INIT;

  cp.git_cmd = 1;

  cp.no_stdin = 1;

  strvec_pushl(&cp.args, "submodule", "update",

         "--recursive", "--rebase", NULL);

  argv_push_verbosity(&cp.args);

  return run_command(&cp);

}

static int update_submodules(void)

{

  struct child_process cp = CHILD_PROCESS_INIT;

  cp.git_cmd = 1;

  cp.no_stdin = 1;

  strvec_pushl(&cp.args, "submodule", "update",

         "--recursive", "--checkout", NULL);

  argv_push_verbosity(&cp.args);

  return run_command(&cp);

}

/**

 * Runs git-merge, returning its exit status.

 */

static int run_merge(void)

{

  struct child_process cmd = CHILD_PROCESS_INIT;

  strvec_pushl(&cmd.args, "merge", NULL);

  /* Shared options */

  argv_push_verbosity(&cmd.args);

  if (opt_progress)

    strvec_push(&cmd.args, opt_progress);

  /* Options passed to git-merge */

  if (opt_diffstat)

    strvec_push(&cmd.args, opt_diffstat);

  if (opt_log)

    strvec_push(&cmd.args, opt_log);

  if (opt_signoff)

    strvec_push(&cmd.args, opt_signoff);

  if (opt_squash)

    strvec_push(&cmd.args, opt_squash);

  if (opt_commit)

    strvec_push(&cmd.args, opt_commit);

  if (opt_edit)

    strvec_push(&cmd.args, opt_edit);

  if (cleanup_arg)

    strvec_pushf(&cmd.args, "--cleanup=%s", cleanup_arg);

  if (opt_ff)

    strvec_push(&cmd.args, opt_ff);

  if (opt_verify)

    strvec_push(&cmd.args, opt_verify);

  if (opt_verify_signatures)

    strvec_push(&cmd.args, opt_verify_signatures);

  strvec_pushv(&cmd.args, opt_strategies.v);

  strvec_pushv(&cmd.args, opt_strategy_opts.v);

  if (opt_gpg_sign)

    strvec_push(&cmd.args, opt_gpg_sign);

  if (opt_autostash == 0)

    strvec_push(&cmd.args, "--no-autostash");

  else if (opt_autostash == 1)

    strvec_push(&cmd.args, "--autostash");

  if (opt_allow_unrelated_histories > 0)

    strvec_push(&cmd.args, "--allow-unrelated-histories");

  strvec_push(&cmd.args, "FETCH_HEAD");

  cmd.git_cmd = 1;

  return run_command(&cmd);

}

/**

 * Returns remote's upstream branch for the current branch. If remote is NULL,

 * the current branch's configured default remote is used. Returns NULL if

 * `remote` does not name a valid remote, HEAD does not point to a branch,

 * remote is not the branch's configured remote or the branch does not have any

 * configured upstream branch.

 */

static const char *get_upstream_branch(const char *remote)

{

  struct remote *rm;

  struct branch *curr_branch;

  const char *curr_branch_remote;

  rm = remote_get(remote);

  if (!rm)

    return NULL;

  curr_branch = branch_get("HEAD");

  if (!curr_branch)

    return NULL;

  curr_branch_remote = remote_for_branch(curr_branch, NULL);

  assert(curr_branch_remote);

  if (strcmp(curr_branch_remote, rm->name))

    return NULL;

  return branch_get_upstream(curr_branch, NULL);

}

/**

 * Derives the remote-tracking branch from the remote and refspec.

 *

 * FIXME: The current implementation assumes the default mapping of

 * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.

 */

static const char *get_tracking_branch(const char *remote, const char *refspec)

{

  struct refspec_item spec;

  const char *spec_src;

  const char *merge_branch;

  refspec_item_init_or_die(&spec, refspec, REFSPEC_FETCH);

  spec_src = spec.src;

  if (!*spec_src || !strcmp(spec_src, "HEAD"))

    spec_src = "HEAD";

  else if (skip_prefix(spec_src, "heads/", &spec_src))

    ;

  else if (skip_prefix(spec_src, "refs/heads/", &spec_src))

    ;

  else if (starts_with(spec_src, "refs/") ||

    starts_with(spec_src, "tags/") ||

    starts_with(spec_src, "remotes/"))

    spec_src = "";

  if (*spec_src) {

    if (!strcmp(remote, "."))

      merge_branch = mkpath("refs/heads/%s", spec_src);

    else

      merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);

  } else

    merge_branch = NULL;

  refspec_item_clear(&spec);

  return merge_branch;

}

/**

 * Given the repo and refspecs, sets fork_point to the point at which the

 * current branch forked from its remote-tracking branch. Returns 0 on success,

 * -1 on failure.

 */

static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,

    const char *refspec)

{

  int ret;

  struct branch *curr_branch;

  const char *remote_branch;

  struct child_process cp = CHILD_PROCESS_INIT;

  struct strbuf sb = STRBUF_INIT;

  curr_branch = branch_get("HEAD");

  if (!curr_branch)

    return -1;

  if (refspec)

    remote_branch = get_tracking_branch(repo, refspec);

  else

    remote_branch = get_upstream_branch(repo);

  if (!remote_branch)

    return -1;

  strvec_pushl(&cp.args, "merge-base", "--fork-point",

         remote_branch, curr_branch->name, NULL);

  cp.no_stdin = 1;

  cp.no_stderr = 1;

  cp.git_cmd = 1;

  ret = capture_command(&cp, &sb, GIT_MAX_HEXSZ);

  if (ret)

    goto cleanup;

  ret = get_oid_hex(sb.buf, fork_point);

  if (ret)

    goto cleanup;

cleanup:

  strbuf_release(&sb);

  return ret ? -1 : 0;

}

/**

 * Sets merge_base to the octopus merge base of curr_head, merge_head and

 * fork_point. Returns 0 if a merge base is found, 1 otherwise.

 */

static int get_octopus_merge_base(struct object_id *merge_base,

    const struct object_id *curr_head,

    const struct object_id *merge_head,

    const struct object_id *fork_point)

{

  struct commit_list *revs = NULL, *result = NULL;

  commit_list_insert(lookup_commit_reference(the_repository, curr_head),

         &revs);

  commit_list_insert(lookup_commit_reference(the_repository, merge_head),

         &revs);

  if (!is_null_oid(fork_point))

    commit_list_insert(lookup_commit_reference(the_repository, fork_point),

           &revs);

  if (get_octopus_merge_bases(revs, &result) < 0)

    exit(128);

  free_commit_list(revs);

  reduce_heads_replace(&result);

  if (!result)

    return 1;

  oidcpy(merge_base, &result->item->object.oid);

  free_commit_list(result);

  return 0;

}

/**

 * Given the current HEAD oid, the merge head returned from git-fetch and the

 * fork point calculated by get_rebase_fork_point(), compute the <newbase> and

 * <upstream> arguments to use for the upcoming git-rebase invocation.

 */

static int get_rebase_newbase_and_upstream(struct object_id *newbase,

    struct object_id *upstream,

    const struct object_id *curr_head,

    const struct object_id *merge_head,

    const struct object_id *fork_point)

{

  struct object_id oct_merge_base;

  if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))

    if (!is_null_oid(fork_point) && oideq(&oct_merge_base, fork_point))

      fork_point = NULL;

  if (fork_point && !is_null_oid(fork_point))

    oidcpy(upstream, fork_point);

  else

    oidcpy(upstream, merge_head);

  oidcpy(newbase, merge_head);

  return 0;

}

/**

 * Given the <newbase> and <upstream> calculated by

 * get_rebase_newbase_and_upstream(), runs git-rebase with the

 * appropriate arguments and returns its exit status.

 */

static int run_rebase(const struct object_id *newbase,

    const struct object_id *upstream)

{

  struct child_process cmd = CHILD_PROCESS_INIT;

  strvec_push(&cmd.args, "rebase");

  /* Shared options */

  argv_push_verbosity(&cmd.args);

  /* Options passed to git-rebase */

  if (opt_rebase == REBASE_MERGES)

    strvec_push(&cmd.args, "--rebase-merges");

  else if (opt_rebase == REBASE_INTERACTIVE)

    strvec_push(&cmd.args, "--interactive");

  if (opt_diffstat)

    strvec_push(&cmd.args, opt_diffstat);

  strvec_pushv(&cmd.args, opt_strategies.v);

  strvec_pushv(&cmd.args, opt_strategy_opts.v);

  if (opt_gpg_sign)

    strvec_push(&cmd.args, opt_gpg_sign);

  if (opt_signoff)

    strvec_push(&cmd.args, opt_signoff);

  if (opt_autostash == 0)

    strvec_push(&cmd.args, "--no-autostash");

  else if (opt_autostash == 1)

    strvec_push(&cmd.args, "--autostash");

  if (opt_verify_signatures &&

      !strcmp(opt_verify_signatures, "--verify-signatures"))

    warning(_("ignoring --verify-signatures for rebase"));

  strvec_push(&cmd.args, "--onto");

  strvec_push(&cmd.args, oid_to_hex(newbase));

  strvec_push(&cmd.args, oid_to_hex(upstream));

  cmd.git_cmd = 1;

  return run_command(&cmd);

}

static int get_can_ff(struct object_id *orig_head,

          struct oid_array *merge_heads)

{

  int ret;

  struct commit_list *list = NULL;

  struct commit *merge_head, *head;

  struct object_id *orig_merge_head;

  if (merge_heads->nr > 1)

    return 0;

  orig_merge_head = &merge_heads->oid[0];

  head = lookup_commit_reference(the_repository, orig_head);

  commit_list_insert(head, &list);

  merge_head = lookup_commit_reference(the_repository, orig_merge_head);

  ret = repo_is_descendant_of(the_repository, merge_head, list);

  free_commit_list(list);

  if (ret < 0)