/src/git/submodule.c

Source
#define USE_THE_REPOSITORY_VARIABLE
#define DISABLE_SIGN_COMPARE_WARNINGS

#include "git-compat-util.h"
#include "abspath.h"
#include "repository.h"
#include "config.h"
#include "submodule-config.h"
#include "submodule.h"
#include "dir.h"
#include "diff.h"
#include "commit.h"
#include "environment.h"
#include "gettext.h"
#include "hex.h"
#include "revision.h"
#include "run-command.h"
#include "diffcore.h"
#include "refs.h"
#include "string-list.h"
#include "oid-array.h"
#include "strvec.h"
#include "thread-utils.h"
#include "path.h"
#include "remote.h"
#include "worktree.h"
#include "parse-options.h"
#include "object-file.h"
#include "object-name.h"
#include "odb.h"
#include "commit-reach.h"
#include "read-cache-ll.h"
#include "setup.h"
#include "advice.h"
#include "url.h"

static int config_update_recurse_submodules = RECURSE_SUBMODULES_OFF;
static int initialized_fetch_ref_tips;
static struct oid_array ref_tips_before_fetch;
static struct oid_array ref_tips_after_fetch;

/*
 * Check if the .gitmodules file is unmerged. Parsing of the .gitmodules file
 * will be disabled because we can't guess what might be configured in
 * .gitmodules unless the user resolves the conflict.
 */
int is_gitmodules_unmerged(struct index_state *istate)
{
  int pos = index_name_pos(istate, GITMODULES_FILE, strlen(GITMODULES_FILE));
  if (pos < 0) { /* .gitmodules not found or isn't merged */
    pos = -1 - pos;
    if (istate->cache_nr > pos) {  /* there is a .gitmodules */
      const struct cache_entry *ce = istate->cache[pos];
      if (ce_namelen(ce) == strlen(GITMODULES_FILE) &&
          !strcmp(ce->name, GITMODULES_FILE))
        return 1;
    }
  }

  return 0;
}

/*
 * Check if the .gitmodules file is safe to write.
 *
 * Writing to the .gitmodules file requires that the file exists in the
 * working tree or, if it doesn't, that a brand new .gitmodules file is going
 * to be created (i.e. it's neither in the index nor in the current branch).
 *
 * It is not safe to write to .gitmodules if it's not in the working tree but
 * it is in the index or in the current branch, because writing new values
 * (and staging them) would blindly overwrite ALL the old content.
 */
int is_writing_gitmodules_ok(void)
{
  struct object_id oid;
  return file_exists(GITMODULES_FILE) ||
    (repo_get_oid(the_repository, GITMODULES_INDEX, &oid) < 0 && repo_get_oid(the_repository, GITMODULES_HEAD, &oid) < 0);
}

/*
 * Check if the .gitmodules file has unstaged modifications.  This must be
 * checked before allowing modifications to the .gitmodules file with the
 * intention to stage them later, because when continuing we would stage the
 * modifications the user didn't stage herself too. That might change in a
 * future version when we learn to stage the changes we do ourselves without
 * staging any previous modifications.
 */
int is_staging_gitmodules_ok(struct index_state *istate)
{
  int pos = index_name_pos(istate, GITMODULES_FILE, strlen(GITMODULES_FILE));

  if ((pos >= 0) && (pos < istate->cache_nr)) {
    struct stat st;
    if (lstat(GITMODULES_FILE, &st) == 0 &&
        ie_modified(istate, istate->cache[pos], &st, 0) & DATA_CHANGED)
      return 0;
  }

  return 1;
}

static int for_each_remote_ref_submodule(const char *submodule,
           each_ref_fn fn, void *cb_data)
{
  return refs_for_each_remote_ref(repo_get_submodule_ref_store(the_repository,
                     submodule),
          fn, cb_data);
}

/*
 * Try to update the "path" entry in the "submodule.<name>" section of the
 * .gitmodules file. Return 0 only if a .gitmodules file was found, a section
 * with the correct path=<oldpath> setting was found and we could update it.
 */
int update_path_in_gitmodules(const char *oldpath, const char *newpath)
{
  struct strbuf entry = STRBUF_INIT;
  const struct submodule *submodule;
  int ret;

  if (!file_exists(GITMODULES_FILE)) /* Do nothing without .gitmodules */
    return -1;

  if (is_gitmodules_unmerged(the_repository->index))
    die(_("Cannot change unmerged .gitmodules, resolve merge conflicts first"));

  submodule = submodule_from_path(the_repository, null_oid(the_hash_algo), oldpath);
  if (!submodule || !submodule->name) {
    warning(_("Could not find section in .gitmodules where path=%s"), oldpath);
    return -1;
  }
  strbuf_addstr(&entry, "submodule.");
  strbuf_addstr(&entry, submodule->name);
  strbuf_addstr(&entry, ".path");
  ret = config_set_in_gitmodules_file_gently(entry.buf, newpath);
  strbuf_release(&entry);
  return ret;
}

/*
 * Try to remove the "submodule.<name>" section from .gitmodules where the given
 * path is configured. Return 0 only if a .gitmodules file was found, a section
 * with the correct path=<path> setting was found and we could remove it.
 */
int remove_path_from_gitmodules(const char *path)
{
  struct strbuf sect = STRBUF_INIT;
  const struct submodule *submodule;

  if (!file_exists(GITMODULES_FILE)) /* Do nothing without .gitmodules */
    return -1;

  if (is_gitmodules_unmerged(the_repository->index))
    die(_("Cannot change unmerged .gitmodules, resolve merge conflicts first"));

  submodule = submodule_from_path(the_repository, null_oid(the_hash_algo), path);
  if (!submodule || !submodule->name) {
    warning(_("Could not find section in .gitmodules where path=%s"), path);
    return -1;
  }
  strbuf_addstr(&sect, "submodule.");
  strbuf_addstr(&sect, submodule->name);
  if (repo_config_rename_section_in_file(the_repository, GITMODULES_FILE, sect.buf, NULL) < 0) {
    /* Maybe the user already did that, don't error out here */
    warning(_("Could not remove .gitmodules entry for %s"), path);
    strbuf_release(&sect);
    return -1;
  }
  strbuf_release(&sect);
  return 0;
}

void stage_updated_gitmodules(struct index_state *istate)
{
  if (add_file_to_index(istate, GITMODULES_FILE, 0))
    die(_("staging updated .gitmodules failed"));
}

void set_diffopt_flags_from_submodule_config(struct diff_options *diffopt,
               const char *path)
{
  const struct submodule *submodule = submodule_from_path(the_repository,
                null_oid(the_hash_algo),
                path);
  if (submodule) {
    const char *ignore;
    char *key;

    key = xstrfmt("submodule.%s.ignore", submodule->name);
    if (repo_config_get_string_tmp(the_repository, key, &ignore))
      ignore = submodule->ignore;
    free(key);

    if (ignore)
      handle_ignore_submodules_arg(diffopt, ignore);
    else if (is_gitmodules_unmerged(the_repository->index))
      diffopt->flags.ignore_submodules = 1;
  }
}

/* Cheap function that only determines if we're interested in submodules at all */
int git_default_submodule_config(const char *var, const char *value,
         void *cb UNUSED)
{
  if (!strcmp(var, "submodule.recurse")) {
    int v = git_config_bool(var, value) ?
      RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
    config_update_recurse_submodules = v;
  }
  return 0;
}

int option_parse_recurse_submodules_worktree_updater(const struct option *opt,
                 const char *arg, int unset)
{
  if (unset) {
    config_update_recurse_submodules = RECURSE_SUBMODULES_OFF;
    return 0;
  }
  if (arg)
    config_update_recurse_submodules =
      parse_update_recurse_submodules_arg(opt->long_name,
                  arg);
  else
    config_update_recurse_submodules = RECURSE_SUBMODULES_ON;

  return 0;
}

/*
 * Determine if a submodule has been initialized at a given 'path'
 */
/*
 * NEEDSWORK: Emit a warning if submodule.active exists, but is valueless,
 * ie, the config looks like: "[submodule] active\n".
 * Since that is an invalid pathspec, we should inform the user.
 */
int is_tree_submodule_active(struct repository *repo,
           const struct object_id *treeish_name,
           const char *path)
{
  int ret = 0;
  char *key = NULL;
  char *value = NULL;
  const struct string_list *sl;
  const struct submodule *module;

  module = submodule_from_path(repo, treeish_name, path);

  /* early return if there isn't a path->module mapping */
  if (!module)
    return 0;

  /* submodule.<name>.active is set */
  key = xstrfmt("submodule.%s.active", module->name);
  if (!repo_config_get_bool(repo, key, &ret)) {
    free(key);
    return ret;
  }
  free(key);

  /* submodule.active is set */
  if (!repo_config_get_string_multi(repo, "submodule.active", &sl)) {
    struct pathspec ps;
    struct strvec args = STRVEC_INIT;
    const struct string_list_item *item;

    for_each_string_list_item(item, sl) {
      strvec_push(&args, item->string);
    }

    parse_pathspec(&ps, 0, 0, NULL, args.v);
    ret = match_pathspec(repo->index, &ps, path, strlen(path), 0, NULL, 1);

    strvec_clear(&args);
    clear_pathspec(&ps);
    return ret;
  }

  /* fallback to checking if the URL is set */
  key = xstrfmt("submodule.%s.url", module->name);
  ret = !repo_config_get_string(repo, key, &value);

  free(value);
  free(key);
  return ret;
}

int is_submodule_active(struct repository *repo, const char *path)
{
  return is_tree_submodule_active(repo, null_oid(the_hash_algo), path);
}

int is_submodule_populated_gently(const char *path, int *return_error_code)
{
  int ret = 0;
  char *gitdir = xstrfmt("%s/.git", path);

  if (resolve_gitdir_gently(gitdir, return_error_code))
    ret = 1;

  free(gitdir);
  return ret;
}

/*
 * Dies if the provided 'prefix' corresponds to an unpopulated submodule
 */
void die_in_unpopulated_submodule(struct index_state *istate,
          const char *prefix)
{
  int i, prefixlen;

  if (!prefix)
    return;

  prefixlen = strlen(prefix);

  for (i = 0; i < istate->cache_nr; i++) {
    struct cache_entry *ce = istate->cache[i];
    int ce_len = ce_namelen(ce);

    if (!S_ISGITLINK(ce->ce_mode))
      continue;
    if (prefixlen <= ce_len)
      continue;
    if (strncmp(ce->name, prefix, ce_len))
      continue;
    if (prefix[ce_len] != '/')
      continue;

    die(_("in unpopulated submodule '%s'"), ce->name);
  }
}

/*
 * Dies if any paths in the provided pathspec descends into a submodule
 */
void die_path_inside_submodule(struct index_state *istate,
             const struct pathspec *ps)
{
  int i, j;

  for (i = 0; i < istate->cache_nr; i++) {
    struct cache_entry *ce = istate->cache[i];
    int ce_len = ce_namelen(ce);

    if (!S_ISGITLINK(ce->ce_mode))
      continue;

    for (j = 0; j < ps->nr ; j++) {
      const struct pathspec_item *item = &ps->items[j];

      if (item->len <= ce_len)
        continue;
      if (item->match[ce_len] != '/')
        continue;
      if (strncmp(ce->name, item->match, ce_len))
        continue;
      if (item->len == ce_len + 1)
        continue;

      die(_("Pathspec '%s' is in submodule '%.*s'"),
          item->original, ce_len, ce->name);
    }
  }
}

enum submodule_update_type parse_submodule_update_type(const char *value)
{
  if (!strcmp(value, "none"))
    return SM_UPDATE_NONE;
  else if (!strcmp(value, "checkout"))
    return SM_UPDATE_CHECKOUT;
  else if (!strcmp(value, "rebase"))
    return SM_UPDATE_REBASE;
  else if (!strcmp(value, "merge"))
    return SM_UPDATE_MERGE;
  else if (*value == '!')
    return SM_UPDATE_COMMAND;
  else
    return SM_UPDATE_UNSPECIFIED;
}

int parse_submodule_update_strategy(const char *value,
    struct submodule_update_strategy *dst)
{
  enum submodule_update_type type;

  free((void*)dst->command);
  dst->command = NULL;

  type = parse_submodule_update_type(value);
  if (type == SM_UPDATE_UNSPECIFIED)
    return -1;

  dst->type = type;
  if (type == SM_UPDATE_COMMAND)
    dst->command = xstrdup(value + 1);

  return 0;
}

void submodule_update_strategy_release(struct submodule_update_strategy *strategy)
{
  free((char *) strategy->command);
}

const char *submodule_update_type_to_string(enum submodule_update_type type)
{
  switch (type) {
  case SM_UPDATE_CHECKOUT:
    return "checkout";
  case SM_UPDATE_MERGE:
    return "merge";
  case SM_UPDATE_REBASE:
    return "rebase";
  case SM_UPDATE_NONE:
    return "none";
  case SM_UPDATE_UNSPECIFIED:
  case SM_UPDATE_COMMAND:
    BUG("init_submodule() should handle type %d", type);
  default:
    BUG("unexpected update strategy type: %d", type);
  }
}

void handle_ignore_submodules_arg(struct diff_options *diffopt,
          const char *arg)
{
  diffopt->flags.ignore_submodule_set = 1;
  diffopt->flags.ignore_submodules = 0;
  diffopt->flags.ignore_untracked_in_submodules = 0;
  diffopt->flags.ignore_dirty_submodules = 0;

  if (!strcmp(arg, "all"))
    diffopt->flags.ignore_submodules = 1;
  else if (!strcmp(arg, "untracked"))
    diffopt->flags.ignore_untracked_in_submodules = 1;
  else if (!strcmp(arg, "dirty"))
    diffopt->flags.ignore_dirty_submodules = 1;
  else if (strcmp(arg, "none"))
    die(_("bad --ignore-submodules argument: %s"), arg);
  /*
   * Please update _git_status() in git-completion.bash when you
   * add new options
   */
}

static int prepare_submodule_diff_summary(struct repository *r, struct rev_info *rev,
            const char *path,
            struct commit *left, struct commit *right,
            struct commit_list *merge_bases)
{
  struct commit_list *list;

  repo_init_revisions(r, rev, NULL);
  setup_revisions(0, NULL, rev, NULL);
  rev->left_right = 1;
  rev->first_parent_only = 1;
  left->object.flags |= SYMMETRIC_LEFT;
  add_pending_object(rev, &left->object, path);
  add_pending_object(rev, &right->object, path);
  for (list = merge_bases; list; list = list->next) {
    list->item->object.flags |= UNINTERESTING;
    add_pending_object(rev, &list->item->object,
      oid_to_hex(&list->item->object.oid));
  }
  return prepare_revision_walk(rev);
}

static void print_submodule_diff_summary(struct repository *r, struct rev_info *rev, struct diff_options *o)
{
  static const char format[] = "  %m %s";
  struct strbuf sb = STRBUF_INIT;
  struct commit *commit;

  while ((commit = get_revision(rev))) {
    struct pretty_print_context ctx = {0};
    ctx.date_mode = rev->date_mode;
    ctx.output_encoding = get_log_output_encoding();
    strbuf_setlen(&sb, 0);
    repo_format_commit_message(r, commit, format, &sb,
              &ctx);
    strbuf_addch(&sb, '\n');
    if (commit->object.flags & SYMMETRIC_LEFT)
      diff_emit_submodule_del(o, sb.buf);
    else
      diff_emit_submodule_add(o, sb.buf);
  }
  strbuf_release(&sb);
}

void prepare_submodule_repo_env(struct strvec *out)
{
  prepare_other_repo_env(out, DEFAULT_GIT_DIR_ENVIRONMENT);
}

static void prepare_submodule_repo_env_in_gitdir(struct strvec *out)
{
  prepare_other_repo_env(out, ".");
}

/*
 * Initialize a repository struct for a submodule based on the provided 'path'.
 *
 * Returns the repository struct on success,
 * NULL when the submodule is not present.
 */
static struct repository *open_submodule(const char *path)
{
  struct strbuf sb = STRBUF_INIT;
  struct repository *out = xmalloc(sizeof(*out));

  if (submodule_to_gitdir(the_repository, &sb, path) ||
      repo_init(out, sb.buf, NULL)) {
    strbuf_release(&sb);
    free(out);
    return NULL;
  }

  /* Mark it as a submodule */
  out->submodule_prefix = xstrdup(path);

  strbuf_release(&sb);
  return out;
}

/*
 * Helper function to display the submodule header line prior to the full
 * summary output.
 *
 * If it can locate the submodule git directory it will create a repository
 * handle for the submodule and lookup both the left and right commits and
 * put them into the left and right pointers.
 */
static void show_submodule_header(struct diff_options *o,
    const char *path,
    struct object_id *one, struct object_id *two,
    unsigned dirty_submodule,
    struct repository *sub,
    struct commit **left, struct commit **right,
    struct commit_list **merge_bases)
{
  const char *message = NULL;
  struct strbuf sb = STRBUF_INIT;
  int fast_forward = 0, fast_backward = 0;

  if (dirty_submodule & DIRTY_SUBMODULE_UNTRACKED)
    diff_emit_submodule_untracked(o, path);

  if (dirty_submodule & DIRTY_SUBMODULE_MODIFIED)
    diff_emit_submodule_modified(o, path);

  if (is_null_oid(one))
    message = "(new submodule)";
  else if (is_null_oid(two))
    message = "(submodule deleted)";

  if (!sub) {
    if (!message)
      message = "(commits not present)";
    goto output_header;
  }

  /*
   * Attempt to lookup the commit references, and determine if this is
   * a fast forward or fast backwards update.
   */
  *left = lookup_commit_reference(sub, one);
  *right = lookup_commit_reference(sub, two);

  /*
   * Warn about missing commits in the submodule project, but only if
   * they aren't null.
   */
  if ((!is_null_oid(one) && !*left) ||
       (!is_null_oid(two) && !*right))
    message = "(commits not present)";

  *merge_bases = NULL;
  if (repo_get_merge_bases(sub, *left, *right, merge_bases) < 0) {
    message = "(corrupt repository)";
    goto output_header;
  }

  if (*merge_bases) {
    if ((*merge_bases)->item == *left)
      fast_forward = 1;
    else if ((*merge_bases)->item == *right)
      fast_backward = 1;
  }

  if (oideq(one, two)) {
    strbuf_release(&sb);
    return;
  }

output_header:
  strbuf_addf(&sb, "Submodule %s ", path);
  strbuf_add_unique_abbrev(&sb, one, DEFAULT_ABBREV);
  strbuf_addstr(&sb, (fast_backward || fast_forward) ? ".." : "...");
  strbuf_add_unique_abbrev(&sb, two, DEFAULT_ABBREV);
  if (message)
    strbuf_addf(&sb, " %s\n", message);
  else
    strbuf_addf(&sb, "%s:\n", fast_backward ? " (rewind)" : "");
  diff_emit_submodule_header(o, sb.buf);

  strbuf_release(&sb);
}

void show_submodule_diff_summary(struct diff_options *o, const char *path,
    struct object_id *one, struct object_id *two,
    unsigned dirty_submodule)
{
  struct rev_info rev = REV_INFO_INIT;
  struct commit *left = NULL, *right = NULL;
  struct commit_list *merge_bases = NULL;
  struct repository *sub;

  sub = open_submodule(path);
  show_submodule_header(o, path, one, two, dirty_submodule,
            sub, &left, &right, &merge_bases);

  /*
   * If we don't have both a left and a right pointer, there is no
   * reason to try and display a summary. The header line should contain
   * all the information the user needs.
   */
  if (!left || !right || !sub)
    goto out;

  /* Treat revision walker failure the same as missing commits */
  if (prepare_submodule_diff_summary(sub, &rev, path, left, right, merge_bases)) {
    diff_emit_submodule_error(o, "(revision walker failed)\n");
    goto out;
  }

  print_submodule_diff_summary(sub, &rev, o);

out:
  commit_list_free(merge_bases);
  release_revisions(&rev);
  clear_commit_marks(left, ~0);
  clear_commit_marks(right, ~0);
  if (sub) {
    repo_clear(sub);
    free(sub);
  }
}

void show_submodule_inline_diff(struct diff_options *o, const char *path,
    struct object_id *one, struct object_id *two,
    unsigned dirty_submodule)
{
  const struct object_id *old_oid = the_hash_algo->empty_tree, *new_oid = the_hash_algo->empty_tree;
  struct commit *left = NULL, *right = NULL;
  struct commit_list *merge_bases = NULL;
  struct child_process cp = CHILD_PROCESS_INIT;
  struct strbuf sb = STRBUF_INIT;
  struct repository *sub;

  sub = open_submodule(path);
  show_submodule_header(o, path, one, two, dirty_submodule,
            sub, &left, &right, &merge_bases);

  /* We need a valid left and right commit to display a difference */
  if (!(left || is_null_oid(one)) ||
      !(right || is_null_oid(two)))
    goto done;

  if (left)
    old_oid = one;
  if (right)
    new_oid = two;

  cp.git_cmd = 1;
  cp.dir = path;
  cp.out = -1;
  cp.no_stdin = 1;

  /* TODO: other options may need to be passed here. */
  strvec_pushl(&cp.args, "diff", "--submodule=diff", NULL);
  strvec_pushf(&cp.args, "--color=%s", want_color(o->use_color) ?
       "always" : "never");

  if (o->flags.reverse_diff) {
    strvec_pushf(&cp.args, "--src-prefix=%s%s/",
           o->b_prefix, path);
    strvec_pushf(&cp.args, "--dst-prefix=%s%s/",
           o->a_prefix, path);
  } else {
    strvec_pushf(&cp.args, "--src-prefix=%s%s/",
           o->a_prefix, path);
    strvec_pushf(&cp.args, "--dst-prefix=%s%s/",
           o->b_prefix, path);
  }
  strvec_push(&cp.args, oid_to_hex(old_oid));
  /*
   * If the submodule has modified content, we will diff against the
   * work tree, under the assumption that the user has asked for the
   * diff format and wishes to actually see all differences even if they
   * haven't yet been committed to the submodule yet.
   */
  if (!(dirty_submodule & DIRTY_SUBMODULE_MODIFIED))
    strvec_push(&cp.args, oid_to_hex(new_oid));

  prepare_submodule_repo_env(&cp.env);

  if (!is_directory(path)) {
    /* fall back to absorbed git dir, if any */
    if (!sub)
      goto done;
    cp.dir = sub->gitdir;
    strvec_push(&cp.env, GIT_DIR_ENVIRONMENT "=.");
    strvec_push(&cp.env, GIT_WORK_TREE_ENVIRONMENT "=.");
  }

  if (start_command(&cp)) {
    diff_emit_submodule_error(o, "(diff failed)\n");
    goto done;
  }

  while (strbuf_getwholeline_fd(&sb, cp.out, '\n') != EOF)
    diff_emit_submodule_pipethrough(o, sb.buf, sb.len);

  if (finish_command(&cp))
    diff_emit_submodule_error(o, "(diff failed)\n");

done:
  strbuf_release(&sb);
  commit_list_free(merge_bases);
  if (left)
    clear_commit_marks(left, ~0);
  if (right)
    clear_commit_marks(right, ~0);
  if (sub) {
    repo_clear(sub);
    free(sub);
  }
}

int should_update_submodules(void)
{
  return config_update_recurse_submodules == RECURSE_SUBMODULES_ON;
}

const struct submodule *submodule_from_ce(const struct cache_entry *ce)
{
  if (!S_ISGITLINK(ce->ce_mode))
    return NULL;

  if (!should_update_submodules())
    return NULL;

  return submodule_from_path(the_repository, null_oid(the_hash_algo), ce->name);
}


struct collect_changed_submodules_cb_data {
  struct repository *repo;
  struct string_list *changed;
  const struct object_id *commit_oid;
};

/*
 * this would normally be two functions: default_name_from_path() and
 * path_from_default_name(). Since the default name is the same as
 * the submodule path we can get away with just one function which only
 * checks whether there is a submodule in the working directory at that
 * location.
 */
static const char *default_name_or_path(const char *path_or_name)
{
  int error_code;

  if (!is_submodule_populated_gently(path_or_name, &error_code))
    return NULL;

  return path_or_name;
}

/*
 * Holds relevant information for a changed submodule. Used as the .util
 * member of the changed submodule name string_list_item.
 *
 * (super_oid, path) allows the submodule config to be read from _some_
 * .gitmodules file. We store this information the first time we find a
 * superproject commit that points to the submodule, but this is
 * arbitrary - we can choose any (super_oid, path) that matches the
 * submodule's name.
 *
 * NEEDSWORK: Storing an arbitrary commit is undesirable because we can't
 * guarantee that we're reading the commit that the user would expect. A better
 * scheme would be to just fetch a submodule by its name. This requires two
 * steps:
 * - Create a function that behaves like repo_submodule_init(), but accepts a
 *   submodule name instead of treeish_name and path. This should be easy
 *   because repo_submodule_init() internally uses the submodule's name.
 *
 * - Replace most instances of 'struct submodule' (which is the .gitmodules
 *   config) with just the submodule name. This is OK because we expect
 *   submodule settings to be stored in .git/config (via "git submodule init"),
 *   not .gitmodules. This also lets us delete get_non_gitmodules_submodule(),
 *   which constructs a bogus 'struct submodule' for the sake of giving a
 *   placeholder name to a gitlink.
 */
struct changed_submodule_data {
  /*
   * The first superproject commit in the rev walk that points to
   * the submodule.
   */
  const struct object_id *super_oid;
  /*
   * Path to the submodule in the superproject commit referenced
   * by 'super_oid'.
   */
  char *path;
  /* The submodule commits that have changed in the rev walk. */
  struct oid_array new_commits;
};

static void changed_submodule_data_clear(struct changed_submodule_data *cs_data)
{
  oid_array_clear(&cs_data->new_commits);
  free(cs_data->path);
}

static void collect_changed_submodules_cb(struct diff_queue_struct *q,
            struct diff_options *options UNUSED,
            void *data)
{
  struct collect_changed_submodules_cb_data *me = data;
  struct string_list *changed = me->changed;
  const struct object_id *commit_oid = me->commit_oid;
  int i;

  for (i = 0; i < q->nr; i++) {
    struct diff_filepair *p = q->queue[i];
    const struct submodule *submodule;
    const char *name;
    struct string_list_item *item;
    struct changed_submodule_data *cs_data;

    if (!S_ISGITLINK(p->two->mode))
      continue;

    submodule = submodule_from_path(me->repo,
            commit_oid, p->two->path);
    if (submodule)
      name = submodule->name;
    else {
      name = default_name_or_path(p->two->path);
      /* make sure name does not collide with existing one */
      if (name)
        submodule = submodule_from_name(me->repo,
                commit_oid, name);
      if (submodule) {
        warning(_("Submodule in commit %s at path: "
          "'%s' collides with a submodule named "
          "the same. Skipping it."),
          oid_to_hex(commit_oid), p->two->path);
        name = NULL;
      }
    }

    if (!name)
      continue;

    item = string_list_insert(changed, name);
    if (item->util)
      cs_data = item->util;
    else {
      item->util = xcalloc(1, sizeof(struct changed_submodule_data));
      cs_data = item->util;
      cs_data->super_oid = commit_oid;
      cs_data->path = xstrdup(p->two->path);
    }
    oid_array_append(&cs_data->new_commits, &p->two->oid);
  }
}

/*
 * Collect the paths of submodules in 'changed' which have changed based on
 * the revisions as specified in 'argv'.  Each entry in 'changed' will also
 * have a corresponding 'struct oid_array' (in the 'util' field) which lists
 * what the submodule pointers were updated to during the change.
 */
static void collect_changed_submodules(struct repository *r,
               struct string_list *changed,
               struct strvec *argv)
{
  struct rev_info rev;
  const struct commit *commit;
  int save_warning;
  struct setup_revision_opt s_r_opt = {
    .assume_dashdash = 1,
  };

  save_warning = warn_on_object_refname_ambiguity;
  warn_on_object_refname_ambiguity = 0;
  repo_init_revisions(r, &rev, NULL);
  setup_revisions_from_strvec(argv, &rev, &s_r_opt);
  warn_on_object_refname_ambiguity = save_warning;
  if (prepare_revision_walk(&rev))
    die(_("revision walk setup failed"));

  while ((commit = get_revision(&rev))) {
    struct rev_info diff_rev;
    struct collect_changed_submodules_cb_data data;
    data.repo = r;
    data.changed = changed;
    data.commit_oid = &commit->object.oid;

    repo_init_revisions(r, &diff_rev, NULL);
    diff_rev.diffopt.output_format |= DIFF_FORMAT_CALLBACK;
    diff_rev.diffopt.format_callback = collect_changed_submodules_cb;
    diff_rev.diffopt.format_callback_data = &data;
    diff_rev.dense_combined_merges = 1;
    diff_tree_combined_merge(commit, &diff_rev);
    release_revisions(&diff_rev);
  }

  reset_revision_walk();
  release_revisions(&rev);
}

static void free_submodules_data(struct string_list *submodules)
{
  struct string_list_item *item;
  for_each_string_list_item(item, submodules)
    changed_submodule_data_clear(item->util);

  string_list_clear(submodules, 1);
}

static int has_remote(const struct reference *ref UNUSED, void *cb_data UNUSED)
{
  return 1;
}

static int append_oid_to_argv(const struct object_id *oid, void *data)
{
  struct strvec *argv = data;
  strvec_push(argv, oid_to_hex(oid));
  return 0;
}

struct has_commit_data {
  struct repository *repo;
  int result;
  const char *path;
  const struct object_id *super_oid;
};

static int check_has_commit(const struct object_id *oid, void *data)
{
  struct has_commit_data *cb = data;
  struct repository subrepo;
  enum object_type type;

  if (repo_submodule_init(&subrepo, cb->repo, cb->path, cb->super_oid)) {
    cb->result = 0;
    /* subrepo failed to init, so don't clean it up. */
    return 0;
  }

  type = odb_read_object_info(subrepo.objects, oid, NULL);

  switch (type) {
  case OBJ_COMMIT:
    goto cleanup;
  case OBJ_BAD:
    /*
     * Object is missing or invalid. If invalid, an error message
     * has already been printed.
     */
    cb->result = 0;
    goto cleanup;
  default:
    die(_("submodule entry '%s' (%s) is a %s, not a commit"),
        cb->path, oid_to_hex(oid), type_name(type));
  }
cleanup:
  repo_clear(&subrepo);
  return 0;
}

static int submodule_has_commits(struct repository *r,
         const char *path,
         const struct object_id *super_oid,
         struct oid_array *commits)
{
  struct has_commit_data has_commit = {
    .repo = r,
    .result = 1,
    .path = path,
    .super_oid = super_oid
  };

  if (validate_submodule_path(path) < 0)
    exit(128);

  oid_array_for_each_unique(commits, check_has_commit, &has_commit);

  if (has_commit.result) {
    /*
     * Even if the submodule is checked out and the commit is
     * present, make sure it exists in the submodule's object store
     * and that it is reachable from a ref.
     */
    struct child_process cp = CHILD_PROCESS_INIT;
    struct strbuf out = STRBUF_INIT;

    strvec_pushl(&cp.args, "rev-list", "-n", "1", NULL);
    oid_array_for_each_unique(commits, append_oid_to_argv, &cp.args);
    strvec_pushl(&cp.args, "--not", "--all", NULL);

    prepare_submodule_repo_env(&cp.env);
    cp.git_cmd = 1;
    cp.no_stdin = 1;
    cp.dir = path;

    if (capture_command(&cp, &out, GIT_MAX_HEXSZ + 1) || out.len)
      has_commit.result = 0;

    strbuf_release(&out);
  }

  return has_commit.result;
}

static int submodule_needs_pushing(struct repository *r,
           const char *path,
           struct oid_array *commits)
{
  if (!submodule_has_commits(r, path, null_oid(the_hash_algo), commits))
    /*
     * NOTE: We do consider it safe to return "no" here. The
     * correct answer would be "We do not know" instead of
     * "No push needed", but it is quite hard to change
     * the submodule pointer without having the submodule
     * around. If a user did however change the submodules
     * without having the submodule around, this indicates
     * an expert who knows what they are doing or a
     * maintainer integrating work from other people. In
     * both cases it should be safe to skip this check.
     */
    return 0;

  if (for_each_remote_ref_submodule(path, has_remote, NULL) > 0) {
    struct child_process cp = CHILD_PROCESS_INIT;
    struct strbuf buf = STRBUF_INIT;
    int needs_pushing = 0;

    strvec_push(&cp.args, "rev-list");
    oid_array_for_each_unique(commits, append_oid_to_argv, &cp.args);
    strvec_pushl(&cp.args, "--not", "--remotes", "-n", "1" , NULL);

    prepare_submodule_repo_env(&cp.env);
    cp.git_cmd = 1;
    cp.no_stdin = 1;
    cp.out = -1;
    cp.dir = path;
    if (start_command(&cp))
      die(_("Could not run 'git rev-list <commits> --not --remotes -n 1' command in submodule %s"),
          path);
    if (strbuf_read(&buf, cp.out, the_hash_algo->hexsz + 1))
      needs_pushing = 1;
    finish_command(&cp);
    close(cp.out);
    strbuf_release(&buf);
    return needs_pushing;
  }

  return 0;
}

int find_unpushed_submodules(struct repository *r,
           struct oid_array *commits,
           const char *remotes_name,
           struct string_list *needs_pushing)
{
  struct string_list submodules = STRING_LIST_INIT_DUP;
  struct string_list_item *name;
  struct strvec argv = STRVEC_INIT;

  /* argv.v[0] will be ignored by setup_revisions */
  strvec_push(&argv, "find_unpushed_submodules");
  oid_array_for_each_unique(commits, append_oid_to_argv, &argv);
  strvec_push(&argv, "--not");
  strvec_pushf(&argv, "--remotes=%s", remotes_name);

  collect_changed_submodules(r, &submodules, &argv);

  for_each_string_list_item(name, &submodules) {
    struct changed_submodule_data *cs_data = name->util;
    const struct submodule *submodule;
    const char *path = NULL;

    submodule = submodule_from_name(r, null_oid(the_hash_algo), name->string);
    if (submodule)
      path = submodule->path;
    else
      path = default_name_or_path(name->string);

    if (!path)
      continue;

    if (submodule_needs_pushing(r, path, &cs_data->new_commits))
      string_list_insert(needs_pushing, path);
  }

  free_submodules_data(&submodules);
  strvec_clear(&argv);

  return needs_pushing->nr;
}

static int push_submodule(const char *path,
        const struct remote *remote,
        const struct refspec *rs,
        const struct string_list *push_options,
        int dry_run)
{
  if (validate_submodule_path(path) < 0)
    exit(128);

  if (for_each_remote_ref_submodule(path, has_remote, NULL) > 0) {
    struct child_process cp = CHILD_PROCESS_INIT;
    strvec_push(&cp.args, "push");
    /*
     * When recursing into a submodule, treat any "only" configurations as "on-
     * demand", since "only" would not work (we need all submodules to be pushed
     * in order to be able to push the superproject).
     */
    strvec_push(&cp.args, "--recurse-submodules=only-is-on-demand");
    if (dry_run)
      strvec_push(&cp.args, "--dry-run");

    if (push_options && push_options->nr) {
      const struct string_list_item *item;
      for_each_string_list_item(item, push_options)
        strvec_pushf(&cp.args, "--push-option=%s",
               item->string);
    }

    if (remote->origin != REMOTE_UNCONFIGURED) {
      int i;
      strvec_push(&cp.args, remote->name);
      for (i = 0; i < rs->nr; i++)
        strvec_push(&cp.args, rs->items[i].raw);
    }

    prepare_submodule_repo_env(&cp.env);
    cp.git_cmd = 1;
    cp.no_stdin = 1;
    cp.dir = path;
    if (run_command(&cp))
      return 0;
    close(cp.out);
  }

  return 1;
}

/*
 * Perform a check in the submodule to see if the remote and refspec work.
 * Die if the submodule can't be pushed.
 */
static void submodule_push_check(const char *path, const char *head,
         const struct remote *remote,
         const struct refspec *rs)
{
  struct child_process cp = CHILD_PROCESS_INIT;
  int i;

  if (validate_submodule_path(path) < 0)
    exit(128);

  strvec_push(&cp.args, "submodule--helper");
  strvec_push(&cp.args, "push-check");
  strvec_push(&cp.args, head);
  strvec_push(&cp.args, remote->name);

  for (i = 0; i < rs->nr; i++)
    strvec_push(&cp.args, rs->items[i].raw);

  prepare_submodule_repo_env(&cp.env);
  cp.git_cmd = 1;
  cp.no_stdin = 1;
  cp.no_stdout = 1;
  cp.dir = path;

  /*
   * Simply indicate if 'submodule--helper push-check' failed.
   * More detailed error information will be provided by the
   * child process.
   */
  if (run_command(&cp))
    die(_("process for submodule '%s' failed"), path);
}

int push_unpushed_submodules(struct repository *r,
           struct oid_array *commits,
           const struct remote *remote,
           const struct refspec *rs,
           const struct string_list *push_options,
           int dry_run)
{
  int i, ret = 1;
  struct string_list needs_pushing = STRING_LIST_INIT_DUP;

  if (!find_unpushed_submodules(r, commits,
              remote->name, &needs_pushing))
    return 1;

  /*
   * Verify that the remote and refspec can be propagated to all
   * submodules.  This check can be skipped if the remote and refspec
   * won't be propagated due to the remote being unconfigured (e.g. a URL
   * instead of a remote name).
   */
  if (remote->origin != REMOTE_UNCONFIGURED) {
    char *head;
    struct object_id head_oid;

    head = refs_resolve_refdup(get_main_ref_store(the_repository),
             "HEAD", 0, &head_oid, NULL);
    if (!head)
      die(_("Failed to resolve HEAD as a valid ref."));

    for (i = 0; i < needs_pushing.nr; i++)
      submodule_push_check(needs_pushing.items[i].string,
               head, remote, rs);
    free(head);
  }

  /* Actually push the submodules */
  for (i = 0; i < needs_pushing.nr; i++) {
    const char *path = needs_pushing.items[i].string;
    fprintf(stderr, _("Pushing submodule '%s'\n"), path);
    if (!push_submodule(path, remote, rs,
            push_options, dry_run)) {
      fprintf(stderr, _("Unable to push submodule '%s'\n"), path);
      ret = 0;
    }
  }

  string_list_clear(&needs_pushing, 0);

  return ret;
}

static int append_oid_to_array(const struct reference *ref, void *data)
{
  struct oid_array *array = data;
  oid_array_append(array, ref->oid);
  return 0;
}

void check_for_new_submodule_commits(struct object_id *oid)
{
  if (!initialized_fetch_ref_tips) {
    refs_for_each_ref(get_main_ref_store(the_repository),
          append_oid_to_array, &ref_tips_before_fetch);
    initialized_fetch_ref_tips = 1;
  }

  oid_array_append(&ref_tips_after_fetch, oid);
}

/*
 * Returns 1 if there is at least one submodule gitdir in
 * $GIT_DIR/modules and 0 otherwise. This follows
 * submodule_name_to_gitdir(), which looks for submodules in
 * $GIT_DIR/modules, not $GIT_COMMON_DIR.
 *
 * A submodule can be moved to $GIT_DIR/modules manually by running "git
 * submodule absorbgitdirs", or it may be initialized there by "git
 * submodule update".
 */
static int repo_has_absorbed_submodules(struct repository *r)
{
  int ret;
  struct strbuf buf = STRBUF_INIT;

  repo_git_path_append(r, &buf, "modules/");
  ret = file_exists(buf.buf) && !is_empty_dir(buf.buf);
  strbuf_release(&buf);
  return ret;
}

static void calculate_changed_submodule_paths(struct repository *r,
    struct string_list *changed_submodule_names)
{
  struct strvec argv = STRVEC_INIT;
  struct string_list_item *name;

  /* No need to check if no submodules would be fetched */
  if (!submodule_from_path(r, NULL, NULL) &&
      !repo_has_absorbed_submodules(r))
    return;

  strvec_push(&argv, "--"); /* argv[0] program name */
  oid_array_for_each_unique(&ref_tips_after_fetch,
           append_oid_to_argv, &argv);
  strvec_push(&argv, "--not");
  oid_array_for_each_unique(&ref_tips_before_fetch,
           append_oid_to_argv, &argv);

  /*
   * Collect all submodules (whether checked out or not) for which new
   * commits have been recorded upstream in "changed_submodule_names".
   */
  collect_changed_submodules(r, changed_submodule_names, &argv);

  for_each_string_list_item(name, changed_submodule_names) {
    struct changed_submodule_data *cs_data = name->util;
    const struct submodule *submodule;
    const char *path = NULL;

    submodule = submodule_from_name(r, null_oid(the_hash_algo), name->string);
    if (submodule)
      path = submodule->path;
    else
      path = default_name_or_path(name->string);

    if (!path)
      continue;

    if (submodule_has_commits(r, path, null_oid(the_hash_algo), &cs_data->new_commits)) {
      changed_submodule_data_clear(cs_data);
      *name->string = '\0';
    }
  }

  string_list_remove_empty_items(changed_submodule_names, 1);

  strvec_clear(&argv);
  oid_array_clear(&ref_tips_before_fetch);
  oid_array_clear(&ref_tips_after_fetch);
  initialized_fetch_ref_tips = 0;
}

int submodule_touches_in_range(struct repository *r,
             struct object_id *excl_oid,
             struct object_id *incl_oid)
{
  struct string_list subs = STRING_LIST_INIT_DUP;
  struct strvec args = STRVEC_INIT;
  int ret;

  /* No need to check if there are no submodules configured */
  if (!submodule_from_path(r, NULL, NULL))
    return 0;

  strvec_push(&args, "--"); /* args[0] program name */
  strvec_push(&args, oid_to_hex(incl_oid));
  if (!is_null_oid(excl_oid)) {
    strvec_push(&args, "--not");
    strvec_push(&args, oid_to_hex(excl_oid));
  }

  collect_changed_submodules(r, &subs, &args);
  ret = subs.nr;

  strvec_clear(&args);

  free_submodules_data(&subs);
  return ret;
}

struct submodule_parallel_fetch {
  /*
   * The index of the last index entry processed by
   * get_fetch_task_from_index().
   */
  int index_count;
  /*
   * The index of the last string_list entry processed by
   * get_fetch_task_from_changed().
   */
  int changed_count;
  struct strvec args;
  struct repository *r;
  const char *prefix;
  int command_line_option;
  int default_option;
  int quiet;
  int result;

  /*
   * Names of submodules that have new commits. Generated by
   * walking the newly fetched superproject commits.
   */
  struct string_list changed_submodule_names;
  /*
   * Names of submodules that have already been processed. Lets us
   * avoid fetching the same submodule more than once.
   */
  struct string_list seen_submodule_names;

  /* Pending fetches by OIDs */
  struct fetch_task **oid_fetch_tasks;
  int oid_fetch_tasks_nr, oid_fetch_tasks_alloc;

  struct strbuf submodules_with_errors;
};
#define SPF_INIT { \
  .args = STRVEC_INIT, \
  .changed_submodule_names = STRING_LIST_INIT_DUP, \
  .seen_submodule_names = STRING_LIST_INIT_DUP, \
  .submodules_with_errors = STRBUF_INIT, \
}

static int get_fetch_recurse_config(const struct submodule *submodule,
            struct submodule_parallel_fetch *spf)
{
  if (spf->command_line_option != RECURSE_SUBMODULES_DEFAULT)
    return spf->command_line_option;

  if (submodule) {
    char *key;
    const char *value;

    int fetch_recurse = submodule->fetch_recurse;
    key = xstrfmt("submodule.%s.fetchRecurseSubmodules", submodule->name);
    if (!repo_config_get_string_tmp(spf->r, key, &value)) {
      fetch_recurse = parse_fetch_recurse_submodules_arg(key, value);
    }
    free(key);

    if (fetch_recurse != RECURSE_SUBMODULES_NONE)
      /* local config overrules everything except commandline */
      return fetch_recurse;
  }

  return spf->default_option;
}

/*
 * Fetch in progress (if callback data) or
 * pending (if in oid_fetch_tasks in struct submodule_parallel_fetch)
 */
struct fetch_task {
  struct repository *repo;
  const struct submodule *sub;
  unsigned free_sub : 1; /* Do we need to free the submodule? */
  const char *default_argv; /* The default fetch mode. */
  struct strvec git_args; /* Args for the child git process. */

  struct oid_array *commits; /* Ensure these commits are fetched */
};

/**
 * When a submodule is not defined in .gitmodules, we cannot access it
 * via the regular submodule-config. Create a fake submodule, which we can
 * work on.
 */
static const struct submodule *get_non_gitmodules_submodule(const char *path)
{
  struct submodule *ret;
  const char *name = default_name_or_path(path);

  if (!name)
    return NULL;

  CALLOC_ARRAY(ret, 1);
  ret->path = name;
  ret->name = name;

  return (const struct submodule *) ret;
}

static void fetch_task_free(struct fetch_task *p)
{
  if (p->free_sub)
    free((void*)p->sub);
  p->free_sub = 0;
  p->sub = NULL;

  if (p->repo)
    repo_clear(p->repo);
  FREE_AND_NULL(p->repo);

  strvec_clear(&p->git_args);
  free(p);
}

static struct repository *get_submodule_repo_for(struct repository *r,
             const char *path,
             const struct object_id *treeish_name)
{
  struct repository *ret = xmalloc(sizeof(*ret));

  if (repo_submodule_init(ret, r, path, treeish_name)) {
    free(ret);
    return NULL;
  }

  return ret;
}

static struct fetch_task *fetch_task_create(struct submodule_parallel_fetch *spf,
              const char *path,
              const struct object_id *treeish_name)
{
  struct fetch_task *task;

  CALLOC_ARRAY(task, 1);

  if (validate_submodule_path(path) < 0)
    exit(128);

  task->sub = submodule_from_path(spf->r, treeish_name, path);

  if (!task->sub) {
    /*
     * No entry in .gitmodules? Technically not a submodule,
     * but historically we supported repositories that happen to be
     * in-place where a gitlink is. Keep supporting them.
     */
    task->sub = get_non_gitmodules_submodule(path);
    if (!task->sub)
      goto cleanup;

    task->free_sub = 1;
  }

  if (string_list_lookup(&spf->seen_submodule_names, task->sub->name))
    goto cleanup;

  switch (get_fetch_recurse_config(task->sub, spf))
  {
  default:
  case RECURSE_SUBMODULES_DEFAULT:
  case RECURSE_SUBMODULES_ON_DEMAND:
    if (!task->sub ||
      !string_list_lookup(
        &spf->changed_submodule_names,
        task->sub->name))
      goto cleanup;
    task->default_argv = "on-demand";
    break;
  case RECURSE_SUBMODULES_ON:
    task->default_argv = "yes";
    break;
  case RECURSE_SUBMODULES_OFF:
    goto cleanup;
  }

  task->repo = get_submodule_repo_for(spf->r, path, treeish_name);

  return task;

 cleanup:
  fetch_task_free(task);
  return NULL;
}

static struct fetch_task *
get_fetch_task_from_index(struct submodule_parallel_fetch *spf,
        struct strbuf *err)
{
  for (; spf->index_count < spf->r->index->cache_nr; spf->index_count++) {
    const struct cache_entry *ce =
      spf->r->index->cache[spf->index_count];
    struct fetch_task *task;

    if (!S_ISGITLINK(ce->ce_mode))
      continue;

    task = fetch_task_create(spf, ce->name, null_oid(the_hash_algo));
    if (!task)
      continue;

    if (task->repo) {
      if (!spf->quiet)
        strbuf_addf(err, _("Fetching submodule %s%s\n"),
              spf->prefix, ce->name);

      spf->index_count++;
      return task;
    } else {
      struct strbuf empty_submodule_path = STRBUF_INIT;

      fetch_task_free(task);

      /*
       * An empty directory is normal,
       * the submodule is not initialized
       */
      strbuf_addf(&empty_submodule_path, "%s/%s/",
              spf->r->worktree,
              ce->name);
      if (S_ISGITLINK(ce->ce_mode) &&
          !is_empty_dir(empty_submodule_path.buf)) {
        spf->result = 1;
        strbuf_addf(err,
              _("Could not access submodule '%s'\n"),
              ce->name);
      }
      strbuf_release(&empty_submodule_path);
    }
  }
  return NULL;
}

static struct fetch_task *
get_fetch_task_from_changed(struct submodule_parallel_fetch *spf,
          struct strbuf *err)
{
  for (; spf->changed_count < spf->changed_submodule_names.nr;
       spf->changed_count++) {
    struct string_list_item item =
      spf->changed_submodule_names.items[spf->changed_count];
    struct changed_submodule_data *cs_data = item.util;
    struct fetch_task *task;

    if (!is_tree_submodule_active(spf->r, cs_data->super_oid,cs_data->path))
      continue;

    task = fetch_task_create(spf, cs_data->path,
           cs_data->super_oid);
    if (!task)
      continue;

    if (!task->repo) {
      strbuf_addf(err, _("Could not access submodule '%s' at commit %s\n"),
            cs_data->path,
            repo_find_unique_abbrev(the_repository, cs_data->super_oid, DEFAULT_ABBREV));

      fetch_task_free(task);
      continue;
    }

    if (!spf->quiet)
      strbuf_addf(err,
            _("Fetching submodule %s%s at commit %s\n"),
            spf->prefix, task->sub->path,
            repo_find_unique_abbrev(the_repository, cs_data->super_oid,
                  DEFAULT_ABBREV));

    spf->changed_count++;
    /*
     * NEEDSWORK: Submodules set/unset a value for
     * core.worktree when they are populated/unpopulated by
     * "git checkout" (and similar commands, see
     * submodule_move_head() and
     * connect_work_tree_and_git_dir()), but if the
     * submodule is unpopulated in another way (e.g. "git
     * rm", "rm -r"), core.worktree will still be set even
     * though the directory doesn't exist, and the child
     * process will crash while trying to chdir into the
     * nonexistent directory.
     *
     * In this case, we know that the submodule has no
     * working tree, so we can work around this by
     * setting "--work-tree=." (--bare does not work because
     * worktree settings take precedence over bare-ness).
     * However, this is not necessarily true in other cases,
     * so a generalized solution is still necessary.
     *
     * Possible solutions:
     * - teach "git [add|rm]" to unset core.worktree and
     *   discourage users from removing submodules without
     *   using a Git command.
     * - teach submodule child processes to ignore stale
     *   core.worktree values.
     */
    strvec_push(&task->git_args, "--work-tree=.");
    return task;
  }
  return NULL;
}

static int get_next_submodule(struct child_process *cp, struct strbuf *err,
            void *data, void **task_cb)
{
  struct submodule_parallel_fetch *spf = data;
  struct fetch_task *task =
    get_fetch_task_from_index(spf, err);
  if (!task)
    task = get_fetch_task_from_changed(spf, err);

  if (task) {
    child_process_init(cp);
    cp->dir = task->repo->gitdir;
    prepare_submodule_repo_env_in_gitdir(&cp->env);
    cp->git_cmd = 1;
    strvec_init(&cp->args);
    if (task->git_args.nr)
      strvec_pushv(&cp->args, task->git_args.v);
    strvec_pushv(&cp->args, spf->args.v);
    strvec_push(&cp->args, task->default_argv);
    strvec_pushf(&cp->args, "--submodule-prefix=%s%s/",
           spf->prefix, task->sub->path);

    *task_cb = task;

    string_list_insert(&spf->seen_submodule_names, task->sub->name);
    return 1;
  }

  if (spf->oid_fetch_tasks_nr) {
    struct fetch_task *task =
      spf->oid_fetch_tasks[spf->oid_fetch_tasks_nr - 1];
    spf->oid_fetch_tasks_nr--;

    child_process_init(cp);
    prepare_submodule_repo_env_in_gitdir(&cp->env);
    cp->git_cmd = 1;
    cp->dir = task->repo->gitdir;

    strvec_init(&cp->args);
    strvec_pushv(&cp->args, spf->args.v);
    strvec_push(&cp->args, "on-demand");
    strvec_pushf(&cp->args, "--submodule-prefix=%s%s/",
           spf->prefix, task->sub->path);

    /* NEEDSWORK: have get_default_remote from submodule--helper */
    strvec_push(&cp->args, "origin");
    oid_array_for_each_unique(task->commits,
            append_oid_to_argv, &cp->args);

    *task_cb = task;
    return 1;
  }

  return 0;
}

static int fetch_start_failure(struct strbuf *err UNUSED,
             void *cb, void *task_cb)
{
  struct submodule_parallel_fetch *spf = cb;
  struct fetch_task *task = task_cb;

  spf->result = 1;

  fetch_task_free(task);
  return 0;
}

static int commit_missing_in_sub(const struct object_id *oid, void *data)
{
  struct repository *subrepo = data;
  enum object_type type = odb_read_object_info(subrepo->objects, oid, NULL);

  return type != OBJ_COMMIT;
}

static int fetch_finish(int retvalue, struct strbuf *err UNUSED,
      void *cb, void *task_cb)
{
  struct submodule_parallel_fetch *spf = cb;
  struct fetch_task *task = task_cb;

  struct string_list_item *it;
  struct changed_submodule_data *cs_data;

  if (!task || !task->sub)
    BUG("callback cookie bogus");

  if (retvalue) {
    /*
     * NEEDSWORK: This indicates that the overall fetch
     * failed, even though there may be a subsequent fetch
     * by commit hash that might work. It may be a good
     * idea to not indicate failure in this case, and only
     * indicate failure if the subsequent fetch fails.
     */
    spf->result = 1;

    strbuf_addf(&spf->submodules_with_errors, "\t%s\n",
          task->sub->name);
  }

  /* Is this the second time we process this submodule? */
  if (task->commits)
    goto out;

  it = string_list_lookup(&spf->changed_submodule_names, task->sub->name);
  if (!it)
    /* Could be an unchanged submodule, not contained in the list */
    goto out;

  cs_data = it->util;
  oid_array_filter(&cs_data->new_commits,
       commit_missing_in_sub,
       task->repo);

  /* Are there commits we want, but do not exist? */
  if (cs_data->new_commits.nr) {
    task->commits = &cs_data->new_commits;
    ALLOC_GROW(spf->oid_fetch_tasks,
         spf->oid_fetch_tasks_nr + 1,
         spf->oid_fetch_tasks_alloc);
    spf->oid_fetch_tasks[spf->oid_fetch_tasks_nr] = task;
    spf->oid_fetch_tasks_nr++;
    return 0;
  }

out:
  fetch_task_free(task);
  return 0;
}

int fetch_submodules(struct repository *r,
         const struct strvec *options,
         const char *prefix, int command_line_option,
         int default_option,
         int quiet, int max_parallel_jobs)
{
  int i;
  struct submodule_parallel_fetch spf = SPF_INIT;
  const struct run_process_parallel_opts opts = {
    .tr2_category = "submodule",
    .tr2_label = "parallel/fetch",

    .processes = max_parallel_jobs,

    .get_next_task = get_next_submodule,
    .start_failure = fetch_start_failure,
    .task_finished = fetch_finish,
    .data = &spf,
  };

  spf.r = r;
  spf.command_line_option = command_line_option;
  spf.default_option = default_option;
  spf.quiet = quiet;
  spf.prefix = prefix;

  if (!r->worktree)
    goto out;

  if (repo_read_index(r) < 0)
    die(_("index file corrupt"));

  strvec_push(&spf.args, "fetch");
  for (i = 0; i < options->nr; i++)
    strvec_push(&spf.args, options->v[i]);
  strvec_push(&spf.args, "--recurse-submodules-default");
  /* default value, "--submodule-prefix" and its value are added later */

  calculate_changed_submodule_paths(r, &spf.changed_submodule_names);
  string_list_sort(&spf.changed_submodule_names);
  run_processes_parallel(&opts);

  if (spf.submodules_with_errors.len > 0)
    fprintf(stderr, _("Errors during submodule fetch:\n%s"),
      spf.submodules_with_errors.buf);


  strvec_clear(&spf.args);
out:
  free_submodules_data(&spf.changed_submodule_names);
  string_list_clear(&spf.seen_submodule_names, 0);
  strbuf_release(&spf.submodules_with_errors);
  free(spf.oid_fetch_tasks);
  return spf.result;
}

unsigned is_submodule_modified(const char *path, int ignore_untracked)
{
  struct child_process cp = CHILD_PROCESS_INIT;
  struct strbuf buf = STRBUF_INIT;
  FILE *fp;
  unsigned dirty_submodule = 0;
  const char *git_dir;
  int ignore_cp_exit_code = 0;

  if (validate_submodule_path(path) < 0)
    exit(128);

  strbuf_addf(&buf, "%s/.git", path);
  git_dir = read_gitfile(buf.buf);
  if (!git_dir)
    git_dir = buf.buf;
  if (!is_git_directory(git_dir)) {
    if (is_directory(git_dir))
      die(_("'%s' not recognized as a git repository"), git_dir);
    strbuf_release(&buf);
    /* The submodule is not checked out, so it is not modified */
    return 0;
  }
  strbuf_reset(&buf);

  strvec_pushl(&cp.args, "status", "--porcelain=2", NULL);
  if (ignore_untracked)
    strvec_push(&cp.args, "-uno");

  prepare_submodule_repo_env(&cp.env);
  cp.git_cmd = 1;
  cp.no_stdin = 1;
  cp.out = -1;
  cp.dir = path;
  if (start_command(&cp))
    die(_("Could not run 'git status --porcelain=2' in submodule %s"), path);

  fp = xfdopen(cp.out, "r");
  while (strbuf_getwholeline(&buf, fp, '\n') != EOF) {
    /* regular untracked files */
    if (buf.buf[0] == '?')
      dirty_submodule |= DIRTY_SUBMODULE_UNTRACKED;

    if (buf.buf[0] == 'u' ||
        buf.buf[0] == '1' ||
        buf.buf[0] == '2') {
      /* T = line type, XY = status, SSSS = submodule state */
      if (buf.len < strlen("T XY SSSS"))
        BUG("invalid status --porcelain=2 line %s",
            buf.buf);

      if (buf.buf[5] == 'S' && buf.buf[8] == 'U')
        /* nested untracked file */
        dirty_submodule |= DIRTY_SUBMODULE_UNTRACKED;

      if (buf.buf[0] == 'u' ||
          buf.buf[0] == '2' ||
          memcmp(buf.buf + 5, "S..U", 4))
        /* other change */
        dirty_submodule |= DIRTY_SUBMODULE_MODIFIED;
    }

    if ((dirty_submodule & DIRTY_SUBMODULE_MODIFIED) &&
        ((dirty_submodule & DIRTY_SUBMODULE_UNTRACKED) ||
         ignore_untracked)) {
      /*
       * We're not interested in any further information from
       * the child any more, neither output nor its exit code.
       */
      ignore_cp_exit_code = 1;
      break;
    }
  }
  fclose(fp);

  if (finish_command(&cp) && !ignore_cp_exit_code)
    die(_("'git status --porcelain=2' failed in submodule %s"), path);

  strbuf_release(&buf);
  return dirty_submodule;
}

int submodule_uses_gitfile(const char *path)
{
  struct child_process cp = CHILD_PROCESS_INIT;
  struct strbuf buf = STRBUF_INIT;
  const char *git_dir;

  if (validate_submodule_path(path) < 0)
    exit(128);

  strbuf_addf(&buf, "%s/.git", path);
  git_dir = read_gitfile(buf.buf);
  if (!git_dir) {
    strbuf_release(&buf);
    return 0;
  }
  strbuf_release(&buf);

  /* Now test that all nested submodules use a gitfile too */
  strvec_pushl(&cp.args,
         "submodule", "foreach", "--quiet", "--recursive",
         "test -f .git", NULL);

  prepare_submodule_repo_env(&cp.env);
  cp.git_cmd = 1;
  cp.no_stdin = 1;
  cp.no_stderr = 1;
  cp.no_stdout = 1;
  cp.dir = path;
  if (run_command(&cp))
    return 0;

  return 1;
}

/*
 * Check if it is a bad idea to remove a submodule, i.e. if we'd lose data
 * when doing so.
 *
 * Return 1 if we'd lose data, return 0 if the removal is fine,
 * and negative values for errors.
 */
int bad_to_remove_submodule(const char *path, unsigned flags)
{
  ssize_t len;
  struct child_process cp = CHILD_PROCESS_INIT;
  struct strbuf buf = STRBUF_INIT;
  int ret = 0;

  if (validate_submodule_path(path) < 0)
    exit(128);

  if (!file_exists(path) || is_empty_dir(path))
    return 0;

  if (!submodule_uses_gitfile(path))
    return 1;

  strvec_pushl(&cp.args, "status", "--porcelain",
         "--ignore-submodules=none", NULL);

  if (flags & SUBMODULE_REMOVAL_IGNORE_UNTRACKED)
    strvec_push(&cp.args, "-uno");
  else
    strvec_push(&cp.args, "-uall");

  if (!(flags & SUBMODULE_REMOVAL_IGNORE_IGNORED_UNTRACKED))
    strvec_push(&cp.args, "--ignored");

  prepare_submodule_repo_env(&cp.env);
  cp.git_cmd = 1;
  cp.no_stdin = 1;
  cp.out = -1;
  cp.dir = path;
  if (start_command(&cp)) {
    if (flags & SUBMODULE_REMOVAL_DIE_ON_ERROR)
      die(_("could not start 'git status' in submodule '%s'"),
        path);
    ret = -1;
    goto out;
  }

  len = strbuf_read(&buf, cp.out, 1024);
  if (len > 2)
    ret = 1;
  close(cp.out);

  if (finish_command(&cp)) {
    if (flags & SUBMODULE_REMOVAL_DIE_ON_ERROR)
      die(_("could not run 'git status' in submodule '%s'"),
        path);
    ret = -1;
  }
out:
  strbuf_release(&buf);
  return ret;
}

void submodule_unset_core_worktree(const struct submodule *sub)
{
  struct strbuf config_path = STRBUF_INIT;

  if (validate_submodule_path(sub->path) < 0)
    exit(128);

  submodule_name_to_gitdir(&config_path, the_repository, sub->name);
  strbuf_addstr(&config_path, "/config");

  if (repo_config_set_in_file_gently(the_repository, config_path.buf, "core.worktree", NULL, NULL))
    warning(_("Could not unset core.worktree setting in submodule '%s'"),
        sub->path);

  strbuf_release(&config_path);
}

static int submodule_has_dirty_index(const struct submodule *sub)
{
  struct child_process cp = CHILD_PROCESS_INIT;

  if (validate_submodule_path(sub->path) < 0)
    exit(128);

  prepare_submodule_repo_env(&cp.env);

  cp.git_cmd = 1;
  strvec_pushl(&cp.args, "diff-index", "--quiet",
         "--cached", "HEAD", NULL);
  cp.no_stdin = 1;
  cp.no_stdout = 1;
  cp.dir = sub->path;
  if (start_command(&cp))
    die(_("could not recurse into submodule '%s'"), sub->path);

  return finish_command(&cp);
}

static void submodule_reset_index(const char *path, const char *super_prefix)
{
  struct child_process cp = CHILD_PROCESS_INIT;

  if (validate_submodule_path(path) < 0)
    exit(128);

  prepare_submodule_repo_env(&cp.env);

  cp.git_cmd = 1;
  cp.no_stdin = 1;
  cp.dir = path;

  /* TODO: determine if this might overwright untracked files */
  strvec_pushl(&cp.args, "read-tree", "-u", "--reset", NULL);
  strvec_pushf(&cp.args, "--super-prefix=%s%s/",
         (super_prefix ? super_prefix : ""), path);

  strvec_push(&cp.args, empty_tree_oid_hex(the_repository->hash_algo));

  if (run_command(&cp))
    die(_("could not reset submodule index"));
}

/**
 * Moves a submodule at a given path from a given head to another new head.
 * For edge cases (a submodule coming into existence or removing a submodule)
 * pass NULL for old or new respectively.
 */
int submodule_move_head(const char *path, const char *super_prefix,
      const char *old_head, const char *new_head,
      unsigned flags)
{
  int ret = 0;
  struct child_process cp = CHILD_PROCESS_INIT;
  const struct submodule *sub;
  int *error_code_ptr, error_code;

  if (!is_submodule_active(the_repository, path))
    return 0;

  if (flags & SUBMODULE_MOVE_HEAD_FORCE)
    /*
     * Pass non NULL pointer to is_submodule_populated_gently
     * to prevent die()-ing. We'll use connect_work_tree_and_git_dir
     * to fixup the submodule in the force case later.
     */
    error_code_ptr = &error_code;
  else
    error_code_ptr = NULL;

  if (old_head && !is_submodule_populated_gently(path, error_code_ptr))
    return 0;

  sub = submodule_from_path(the_repository, null_oid(the_hash_algo), path);

  if (!sub)
    BUG("could not get submodule information for '%s'", path);

  if (old_head && !(flags & SUBMODULE_MOVE_HEAD_FORCE)) {
    /* Check if the submodule has a dirty index. */
    if (submodule_has_dirty_index(sub))
      return error(_("submodule '%s' has dirty index"), path);
  }

  if (!(flags & SUBMODULE_MOVE_HEAD_DRY_RUN)) {
    if (old_head) {
      if (!submodule_uses_gitfile(path))
        absorb_git_dir_into_superproject(path,
                 super_prefix);
      else {
        char *dotgit = xstrfmt("%s/.git", path);
        char *git_dir = xstrdup(read_gitfile(dotgit));

        free(dotgit);
        if (validate_submodule_git_dir(git_dir,
                     sub->name) < 0)
          die(_("refusing to create/use '%s' in "
                "another submodule's git dir. "
                "Enabling extensions.submodulePathConfig "
                "should fix this."), git_dir);
        free(git_dir);
      }
    } else {
      struct strbuf gitdir = STRBUF_INIT;
      submodule_name_to_gitdir(&gitdir, the_repository,
             sub->name);
      connect_work_tree_and_git_dir(path, gitdir.buf, 0);
      strbuf_release(&gitdir);

      /* make sure the index is clean as well */
      submodule_reset_index(path, super_prefix);
    }

    if (old_head && (flags & SUBMODULE_MOVE_HEAD_FORCE)) {
      struct strbuf gitdir = STRBUF_INIT;
      submodule_name_to_gitdir(&gitdir, the_repository,
             sub->name);
      connect_work_tree_and_git_dir(path, gitdir.buf, 1);
      strbuf_release(&gitdir);
    }
  }

  prepare_submodule_repo_env(&cp.env);

  cp.git_cmd = 1;
  cp.no_stdin = 1;
  cp.dir = path;

  strvec_pushl(&cp.args, "read-tree", "--recurse-submodules", NULL);
  strvec_pushf(&cp.args, "--super-prefix=%s%s/",
         (super_prefix ? super_prefix : ""), path);

  if (flags & SUBMODULE_MOVE_HEAD_DRY_RUN)
    strvec_push(&cp.args, "-n");
  else
    strvec_push(&cp.args, "-u");

  if (flags & SUBMODULE_MOVE_HEAD_FORCE)
    strvec_push(&cp.args, "--reset");
  else
    strvec_push(&cp.args, "-m");

  if (!(flags & SUBMODULE_MOVE_HEAD_FORCE))
    strvec_push(&cp.args, old_head ? old_head : empty_tree_oid_hex(the_repository->hash_algo));

  strvec_push(&cp.args, new_head ? new_head : empty_tree_oid_hex(the_repository->hash_algo));

  if (run_command(&cp)) {
    ret = error(_("Submodule '%s' could not be updated."), path);
    goto out;
  }

  if (!(flags & SUBMODULE_MOVE_HEAD_DRY_RUN)) {
    if (new_head) {
      child_process_init(&cp);
      /* also set the HEAD accordingly */
      cp.git_cmd = 1;
      cp.no_stdin = 1;
      cp.dir = path;

      prepare_submodule_repo_env(&cp.env);
      strvec_pushl(&cp.args, "update-ref", "HEAD",
             "--no-deref", new_head, NULL);

      if (run_command(&cp)) {
        ret = -1;
        goto out;
      }
    } else {
      struct strbuf sb = STRBUF_INIT;

      strbuf_addf(&sb, "%s/.git", path);
      unlink_or_warn(sb.buf);
      strbuf_release(&sb);

      if (is_empty_dir(path))
        rmdir_or_warn(path);

      submodule_unset_core_worktree(sub);
    }
  }
out:
  return ret;
}

static int check_casefolding_conflict(const char *git_dir,
              const char *submodule_name,
              const bool suffixes_match)
{
  char *p, *modules_dir = xstrdup(git_dir);
  struct dirent *de;
  DIR *dir = NULL;
  int ret = 0;

  if ((p = find_last_dir_sep(modules_dir)))
    *p = '\0';

  /* No conflict is possible if modules_dir doesn't exist (first clone) */
  if (!is_directory(modules_dir))
    goto cleanup;

  dir = opendir(modules_dir);
  if (!dir) {
    ret = -1;
    goto cleanup;
  }

  /* Check for another directory under .git/modules that differs only in case. */
  while ((de = readdir(dir))) {
    if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, ".."))
      continue;

    if ((suffixes_match || is_git_directory(git_dir)) &&
        !strcasecmp(de->d_name, submodule_name) &&
        strcmp(de->d_name, submodule_name)) {
      ret = -1; /* collision found */
      break;
    }
  }

cleanup:
  if (dir)
    closedir(dir);
  free(modules_dir);
  return ret;
}

struct submodule_from_gitdir_cb {
  const char *gitdir;
  const char *submodule_name;
  bool conflict_found;
};

static int find_conflict_by_gitdir_cb(const char *var, const char *value,
              const struct config_context *ctx UNUSED, void *data)
{
  struct submodule_from_gitdir_cb *cb = data;
  const char *submodule_name_start;
  size_t submodule_name_len;
  const char *suffix = ".gitdir";
  size_t suffix_len = strlen(suffix);

  if (!skip_prefix(var, "submodule.", &submodule_name_start))
    return 0;

  /* Check if submodule_name_start ends with ".gitdir" */
  submodule_name_len = strlen(submodule_name_start);
  if (submodule_name_len < suffix_len ||
      strcmp(submodule_name_start + submodule_name_len - suffix_len, suffix) != 0)
    return 0; /* Does not end with ".gitdir" */

  submodule_name_len -= suffix_len;

  /*
   * A conflict happens if:
   * 1. The submodule names are different and
   * 2. The gitdir paths resolve to the same absolute path
   */
  if (value && strncmp(cb->submodule_name, submodule_name_start, submodule_name_len)) {
    char *abs_path_cb = absolute_pathdup(cb->gitdir);
    char *abs_path_value = absolute_pathdup(value);

    cb->conflict_found = !strcmp(abs_path_cb, abs_path_value);

    free(abs_path_cb);
    free(abs_path_value);
  }

  return cb->conflict_found;
}

static bool submodule_conflicts_with_existing(const char *gitdir, const char *submodule_name)
{
  struct submodule_from_gitdir_cb cb = { 0 };
  cb.submodule_name = submodule_name;
  cb.gitdir = gitdir;

  /* Find conflicts with existing repo gitdir configs */
  repo_config(the_repository, find_conflict_by_gitdir_cb, &cb);

  return cb.conflict_found;
}

/*
 * Encoded gitdir validation, only used when extensions.submodulePathConfig is enabled.
 * This does not print errors like the non-encoded version, because encoding is supposed
 * to mitigate / fix all these.
 */
static int validate_submodule_encoded_git_dir(char *git_dir, const char *submodule_name)
{
  const char *modules_marker = "/modules/";
  char *p = git_dir, *last_submodule_name = NULL;
  int config_ignorecase = 0;

  if (!the_repository->repository_format_submodule_path_cfg)
    BUG("validate_submodule_encoded_git_dir() must be called with "
        "extensions.submodulePathConfig enabled.");

  /* Find the last submodule name in the gitdir path (modules can be nested). */
  while ((p = strstr(p, modules_marker))) {
    last_submodule_name = p + strlen(modules_marker);
    p++;
  }

  /* Prevent the use of '/' in encoded names */
  if (!last_submodule_name || strchr(last_submodule_name, '/'))
    return -1;

  /* Prevent conflicts with existing submodule gitdirs */
  if (is_git_directory(git_dir) &&
      submodule_conflicts_with_existing(git_dir, submodule_name))
      return -1;

  /* Prevent conflicts on case-folding filesystems */
  repo_config_get_bool(the_repository, "core.ignorecase", &config_ignorecase);
  if (ignore_case || config_ignorecase) {
    bool suffixes_match = !strcmp(last_submodule_name, submodule_name);
    return check_casefolding_conflict(git_dir, submodule_name,
              suffixes_match);
  }

  return 0;
}

static int validate_submodule_legacy_git_dir(char *git_dir, const char *submodule_name)
{
  size_t len = strlen(git_dir), suffix_len = strlen(submodule_name);
  char *p;
  int ret = 0;

  if (the_repository->repository_format_submodule_path_cfg)
    BUG("validate_submodule_git_dir() must be called with "
        "extensions.submodulePathConfig disabled.");

  if (len <= suffix_len || (p = git_dir + len - suffix_len)[-1] != '/' ||
      strcmp(p, submodule_name))
    BUG("submodule name '%s' not a suffix of git dir '%s'",
        submodule_name, git_dir);

  /*
   * We prevent the contents of sibling submodules' git directories to
   * clash.
   *
   * Example: having a submodule named `hippo` and another one named
   * `hippo/hooks` would result in the git directories
   * `.git/modules/hippo/` and `.git/modules/hippo/hooks/`, respectively,
   * but the latter directory is already designated to contain the hooks
   * of the former.
   */
  for (; *p; p++) {
    if (is_dir_sep(*p)) {
      char c = *p;

      *p = '\0';
      if (is_git_directory(git_dir))
        ret = -1;
      *p = c;

      if (ret < 0)
        return error(_("submodule git dir '%s' is "
                 "inside git dir '%.*s'"),
               git_dir,
               (int)(p - git_dir), git_dir);
    }
  }

  return 0;
}

int validate_submodule_git_dir(char *git_dir, const char *submodule_name)
{
  if (!the_repository->repository_format_submodule_path_cfg)
    return validate_submodule_legacy_git_dir(git_dir, submodule_name);

  return validate_submodule_encoded_git_dir(git_dir, submodule_name);
}

int validate_submodule_path(const char *path)
{
  char *p = xstrdup(path);
  struct stat st;
  int i, ret = 0;
  char sep;

  for (i = 0; !ret && p[i]; i++) {
    if (!is_dir_sep(p[i]))
      continue;

    sep = p[i];
    p[i] = '\0';
    /* allow missing components, but no symlinks */
    ret = lstat(p, &st) || !S_ISLNK(st.st_mode) ? 0 : -1;
    p[i] = sep;
    if (ret)
      error(_("expected '%.*s' in submodule path '%s' not to "
        "be a symbolic link"), i, p, p);
  }
  if (!lstat(p, &st) && S_ISLNK(st.st_mode))
    ret = error(_("expected submodule path '%s' not to be a "
            "symbolic link"), p);
  free(p);
  return ret;
}


/*
 * Embeds a single submodules git directory into the superprojects git dir,
 * non recursively.
 */
static void relocate_single_git_dir_into_superproject(const char *path,
                  const char *super_prefix)
{
  char *old_git_dir = NULL, *real_old_git_dir = NULL, *real_new_git_dir = NULL;
  struct strbuf new_gitdir = STRBUF_INIT;
  const struct submodule *sub;

  if (validate_submodule_path(path) < 0)
    exit(128);

  if (submodule_uses_worktrees(path))
    die(_("relocate_gitdir for submodule '%s' with "
          "more than one worktree not supported"), path);

  old_git_dir = xstrfmt("%s/.git", path);
  if (read_gitfile(old_git_dir))
    /* If it is an actual gitfile, it doesn't need migration. */
    return;

  real_old_git_dir = real_pathdup(old_git_dir, 1);

  sub = submodule_from_path(the_repository, null_oid(the_hash_algo), path);
  if (!sub)
    die(_("could not lookup name for submodule '%s'"), path);

  submodule_name_to_gitdir(&new_gitdir, the_repository, sub->name);
  if (safe_create_leading_directories_const(the_repository, new_gitdir.buf) < 0)
    die(_("could not create directory '%s'"), new_gitdir.buf);
  real_new_git_dir = real_pathdup(new_gitdir.buf, 1);

  fprintf(stderr, _("Migrating git directory of '%s%s' from\n'%s' to\n'%s'\n"),
    super_prefix ? super_prefix : "", path,
    real_old_git_dir, real_new_git_dir);

  relocate_gitdir(path, real_old_git_dir, real_new_git_dir);

  free(old_git_dir);
  free(real_old_git_dir);
  free(real_new_git_dir);
  strbuf_release(&new_gitdir);
}

static void absorb_git_dir_into_superproject_recurse(const char *path,
                 const char *super_prefix)
{

  struct child_process cp = CHILD_PROCESS_INIT;

  if (validate_submodule_path(path) < 0)
    exit(128);

  cp.dir = path;
  cp.git_cmd = 1;
  cp.no_stdin = 1;
  strvec_pushl(&cp.args, "submodule--helper",
         "absorbgitdirs", NULL);
  strvec_pushf(&cp.args, "--super-prefix=%s%s/", super_prefix ?
         super_prefix : "", path);

  prepare_submodule_repo_env(&cp.env);
  if (run_command(&cp))
    die(_("could not recurse into submodule '%s'"), path);
}

/*
 * Migrate the git directory of the submodule given by path from
 * having its git directory within the working tree to the git dir nested
 * in its superprojects git dir under modules/.
 */
void absorb_git_dir_into_superproject(const char *path,
              const char *super_prefix)
{
  int err_code;
  const char *sub_git_dir;
  struct strbuf gitdir = STRBUF_INIT;

  if (validate_submodule_path(path) < 0)
    exit(128);

  strbuf_addf(&gitdir, "%s/.git", path);
  sub_git_dir = resolve_gitdir_gently(gitdir.buf, &err_code);

  /* Not populated? */
  if (!sub_git_dir) {
    const struct submodule *sub;
    struct strbuf sub_gitdir = STRBUF_INIT;

    if (err_code == READ_GITFILE_ERR_STAT_FAILED) {
      /* unpopulated as expected */
      strbuf_release(&gitdir);
      return;
    }

    if (err_code != READ_GITFILE_ERR_NOT_A_REPO)
      /* We don't know what broke here. */
      read_gitfile_error_die(err_code, path, NULL);

    /*
    * Maybe populated, but no git directory was found?
    * This can happen if the superproject is a submodule
    * itself and was just absorbed. The absorption of the
    * superproject did not rewrite the git file links yet,
    * fix it now.
    */
    sub = submodule_from_path(the_repository, null_oid(the_hash_algo), path);
    if (!sub)
      die(_("could not lookup name for submodule '%s'"), path);
    submodule_name_to_gitdir(&sub_gitdir, the_repository, sub->name);
    connect_work_tree_and_git_dir(path, sub_gitdir.buf, 0);
    strbuf_release(&sub_gitdir);
  } else {
    /* Is it already absorbed into the superprojects git dir? */
    char *real_sub_git_dir = real_pathdup(sub_git_dir, 1);
    char *real_common_git_dir = real_pathdup(repo_get_common_dir(the_repository), 1);

    if (!starts_with(real_sub_git_dir, real_common_git_dir))
      relocate_single_git_dir_into_superproject(path, super_prefix);

    free(real_sub_git_dir);
    free(real_common_git_dir);
  }
  strbuf_release(&gitdir);

  absorb_git_dir_into_superproject_recurse(path, super_prefix);
}

int get_superproject_working_tree(struct strbuf *buf)
{
  struct child_process cp = CHILD_PROCESS_INIT;
  struct strbuf sb = STRBUF_INIT;
  struct strbuf one_up = STRBUF_INIT;
  char *cwd = xgetcwd();
  int ret = 0;
  const char *subpath;
  int code;
  ssize_t len;

  if (!is_inside_work_tree())
    /*
     * FIXME:
     * We might have a superproject, but it is harder
     * to determine.
     */
    return 0;

  if (!strbuf_realpath(&one_up, "../", 0))
    return 0;

  subpath = relative_path(cwd, one_up.buf, &sb);
  strbuf_release(&one_up);

  prepare_submodule_repo_env(&cp.env);
  strvec_pop(&cp.env);

  strvec_pushl(&cp.args, "--literal-pathspecs", "-C", "..",
         "ls-files", "-z", "--stage", "--full-name", "--",
         subpath, NULL);
  strbuf_reset(&sb);

  cp.no_stdin = 1;
  cp.no_stderr = 1;
  cp.out = -1;
  cp.git_cmd = 1;

  if (start_command(&cp))
    die(_("could not start ls-files in .."));

  len = strbuf_read(&sb, cp.out, PATH_MAX);
  close(cp.out);

  if (starts_with(sb.buf, "160000")) {
    int super_sub_len;
    int cwd_len = strlen(cwd);
    char *super_sub, *super_wt;

    /*
     * There is a superproject having this repo as a submodule.
     * The format is <mode> SP <hash> SP <stage> TAB <full name> \0,
     * We're only interested in the name after the tab.
     */
    super_sub = strchr(sb.buf, '\t') + 1;
    super_sub_len = strlen(super_sub);

    if (super_sub_len > cwd_len ||
        strcmp(&cwd[cwd_len - super_sub_len], super_sub))
      BUG("returned path string doesn't match cwd?");

    super_wt = xstrdup(cwd);
    super_wt[cwd_len - super_sub_len] = '\0';

    strbuf_realpath(buf, super_wt, 1);
    ret = 1;
    free(super_wt);
  }
  free(cwd);
  strbuf_release(&sb);

  code = finish_command(&cp);

  if (code == 128)
    /* '../' is not a git repository */
    return 0;
  if (code == 0 && len == 0)
    /* There is an unrelated git repository at '../' */
    return 0;
  if (code)
    die(_("ls-tree returned unexpected return code %d"), code);

  return ret;
}

/*
 * Put the gitdir for a submodule (given relative to the main
 * repository worktree) into `buf`, or return -1 on error.
 */
int submodule_to_gitdir(struct repository *repo,
      struct strbuf *buf, const char *submodule)
{
  const struct submodule *sub;
  const char *git_dir;
  int ret = 0;

  if (validate_submodule_path(submodule) < 0)
    exit(128);

  strbuf_reset(buf);
  strbuf_addstr(buf, submodule);
  strbuf_complete(buf, '/');
  strbuf_addstr(buf, ".git");

  git_dir = read_gitfile(buf->buf);
  if (git_dir) {
    strbuf_reset(buf);
    strbuf_addstr(buf, git_dir);
  }
  if (!is_git_directory(buf->buf)) {
    sub = submodule_from_path(repo, null_oid(the_hash_algo), submodule);
    if (!sub) {
      ret = -1;
      goto cleanup;
    }
    strbuf_reset(buf);
    submodule_name_to_gitdir(buf, repo, sub->name);
  }

cleanup:
  return ret;
}

void submodule_name_to_gitdir(struct strbuf *buf, struct repository *r,
            const char *submodule_name)
{
  if (!r->repository_format_submodule_path_cfg) {
    /*
     * If extensions.submodulePathConfig is disabled,
     * continue to use the plain path.
     */
    repo_git_path_append(r, buf, "modules/%s", submodule_name);
  } else {
    const char *gitdir;
    char *key;
    int ret;

    /* Otherwise the extension is enabled, so use the gitdir config. */
    key = xstrfmt("submodule.%s.gitdir", submodule_name);
    ret = repo_config_get_string_tmp(r, key, &gitdir);
    FREE_AND_NULL(key);

    if (ret)
      die(_("the 'submodule.%s.gitdir' config does not exist for module '%s'. "
            "Please ensure it is set, for example by running something like: "
            "'git config submodule.%s.gitdir .git/modules/%s'. For details "
            "see the extensions.submodulePathConfig documentation."),
          submodule_name, submodule_name, submodule_name, submodule_name);

    strbuf_addstr(buf, gitdir);
  }

  /* validate because users might have modified the config */
  if (validate_submodule_git_dir(buf->buf, submodule_name)) {
    advise(_("enabling extensions.submodulePathConfig might fix the "
       "following error, if it's not already enabled."));
    die(_("refusing to create/use '%s' in another submodule's "
          " git dir."), buf->buf);
  }
}

Coverage Report

Created: 2026-02-14 06:27