--- /dev/null
+#include "builtin.h"
+#include "config.h"
+#include "parse-options.h"
+#include "refs.h"
+#include "lockfile.h"
+#include "cache-tree.h"
+#include "unpack-trees.h"
+#include "merge-recursive.h"
+#include "argv-array.h"
+#include "run-command.h"
+#include "dir.h"
+#include "rerere.h"
+
+static const char * const git_stash_helper_usage[] = {
+ N_("git stash--helper apply [--index] [-q|--quiet] [<stash>]"),
+ NULL
+};
+
+static const char * const git_stash_helper_apply_usage[] = {
+ N_("git stash--helper apply [--index] [-q|--quiet] [<stash>]"),
+ NULL
+};
+
+static const char *ref_stash = "refs/stash";
+static struct strbuf stash_index_path = STRBUF_INIT;
+
+/*
+ * w_commit is set to the commit containing the working tree
+ * b_commit is set to the base commit
+ * i_commit is set to the commit containing the index tree
+ * u_commit is set to the commit containing the untracked files tree
+ * w_tree is set to the working tree
+ * b_tree is set to the base tree
+ * i_tree is set to the index tree
+ * u_tree is set to the untracked files tree
+ */
+struct stash_info {
+ struct object_id w_commit;
+ struct object_id b_commit;
+ struct object_id i_commit;
+ struct object_id u_commit;
+ struct object_id w_tree;
+ struct object_id b_tree;
+ struct object_id i_tree;
+ struct object_id u_tree;
+ struct strbuf revision;
+ int is_stash_ref;
+ int has_u;
+};
+
+static void free_stash_info(struct stash_info *info)
+{
+ strbuf_release(&info->revision);
+}
+
+static void assert_stash_like(struct stash_info *info, const char *revision)
+{
+ if (get_oidf(&info->b_commit, "%s^1", revision) ||
+ get_oidf(&info->w_tree, "%s:", revision) ||
+ get_oidf(&info->b_tree, "%s^1:", revision) ||
+ get_oidf(&info->i_tree, "%s^2:", revision))
+ die(_("'%s' is not a stash-like commit"), revision);
+}
+
+static int get_stash_info(struct stash_info *info, int argc, const char **argv)
+{
+ int ret;
+ char *end_of_rev;
+ char *expanded_ref;
+ const char *revision;
+ const char *commit = NULL;
+ struct object_id dummy;
+ struct strbuf symbolic = STRBUF_INIT;
+
+ if (argc > 1) {
+ int i;
+ struct strbuf refs_msg = STRBUF_INIT;
+
+ for (i = 0; i < argc; i++)
+ strbuf_addf(&refs_msg, " '%s'", argv[i]);
+
+ fprintf_ln(stderr, _("Too many revisions specified:%s"),
+ refs_msg.buf);
+ strbuf_release(&refs_msg);
+
+ return -1;
+ }
+
+ if (argc == 1)
+ commit = argv[0];
+
+ strbuf_init(&info->revision, 0);
+ if (!commit) {
+ if (!ref_exists(ref_stash)) {
+ free_stash_info(info);
+ fprintf_ln(stderr, _("No stash entries found."));
+ return -1;
+ }
+
+ strbuf_addf(&info->revision, "%s@{0}", ref_stash);
+ } else if (strspn(commit, "0123456789") == strlen(commit)) {
+ strbuf_addf(&info->revision, "%s@{%s}", ref_stash, commit);
+ } else {
+ strbuf_addstr(&info->revision, commit);
+ }
+
+ revision = info->revision.buf;
+
+ if (get_oid(revision, &info->w_commit)) {
+ error(_("%s is not a valid reference"), revision);
+ free_stash_info(info);
+ return -1;
+ }
+
+ assert_stash_like(info, revision);
+
+ info->has_u = !get_oidf(&info->u_tree, "%s^3:", revision);
+
+ end_of_rev = strchrnul(revision, '@');
+ strbuf_add(&symbolic, revision, end_of_rev - revision);
+
+ ret = dwim_ref(symbolic.buf, symbolic.len, &dummy, &expanded_ref);
+ strbuf_release(&symbolic);
+ switch (ret) {
+ case 0: /* Not found, but valid ref */
+ info->is_stash_ref = 0;
+ break;
+ case 1:
+ info->is_stash_ref = !strcmp(expanded_ref, ref_stash);
+ break;
+ default: /* Invalid or ambiguous */
+ free_stash_info(info);
+ }
+
+ free(expanded_ref);
+ return !(ret == 0 || ret == 1);
+}
+
+static int reset_tree(struct object_id *i_tree, int update, int reset)
+{
+ int nr_trees = 1;
+ struct unpack_trees_options opts;
+ struct tree_desc t[MAX_UNPACK_TREES];
+ struct tree *tree;
+ struct lock_file lock_file = LOCK_INIT;
+
+ read_cache_preload(NULL);
+ if (refresh_cache(REFRESH_QUIET))
+ return -1;
+
+ hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
+
+ memset(&opts, 0, sizeof(opts));
+
+ tree = parse_tree_indirect(i_tree);
+ if (parse_tree(tree))
+ return -1;
+
+ init_tree_desc(t, tree->buffer, tree->size);
+
+ opts.head_idx = 1;
+ opts.src_index = &the_index;
+ opts.dst_index = &the_index;
+ opts.merge = 1;
+ opts.reset = reset;
+ opts.update = update;
+ opts.fn = oneway_merge;
+
+ if (unpack_trees(nr_trees, t, &opts))
+ return -1;
+
+ if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
+ return error(_("unable to write new index file"));
+
+ return 0;
+}
+
+static int diff_tree_binary(struct strbuf *out, struct object_id *w_commit)
+{
+ struct child_process cp = CHILD_PROCESS_INIT;
+ const char *w_commit_hex = oid_to_hex(w_commit);
+
+ /*
+ * Diff-tree would not be very hard to replace with a native function,
+ * however it should be done together with apply_cached.
+ */
+ cp.git_cmd = 1;
+ argv_array_pushl(&cp.args, "diff-tree", "--binary", NULL);
+ argv_array_pushf(&cp.args, "%s^2^..%s^2", w_commit_hex, w_commit_hex);
+
+ return pipe_command(&cp, NULL, 0, out, 0, NULL, 0);
+}
+
+static int apply_cached(struct strbuf *out)
+{
+ struct child_process cp = CHILD_PROCESS_INIT;
+
+ /*
+ * Apply currently only reads either from stdin or a file, thus
+ * apply_all_patches would have to be updated to optionally take a
+ * buffer.
+ */
+ cp.git_cmd = 1;
+ argv_array_pushl(&cp.args, "apply", "--cached", NULL);
+ return pipe_command(&cp, out->buf, out->len, NULL, 0, NULL, 0);
+}
+
+static int reset_head(void)
+{
+ struct child_process cp = CHILD_PROCESS_INIT;
+
+ /*
+ * Reset is overall quite simple, however there is no current public
+ * API for resetting.
+ */
+ cp.git_cmd = 1;
+ argv_array_push(&cp.args, "reset");
+
+ return run_command(&cp);
+}
+
+static int get_newly_staged(struct strbuf *out, struct object_id *c_tree)
+{
+ struct child_process cp = CHILD_PROCESS_INIT;
+ const char *c_tree_hex = oid_to_hex(c_tree);
+
+ /*
+ * diff-index is very similar to diff-tree above, and should be
+ * converted together with update_index.
+ */
+ cp.git_cmd = 1;
+ argv_array_pushl(&cp.args, "diff-index", "--cached", "--name-only",
+ "--diff-filter=A", NULL);
+ argv_array_push(&cp.args, c_tree_hex);
+ return pipe_command(&cp, NULL, 0, out, 0, NULL, 0);
+}
+
+static int update_index(struct strbuf *out)
+{
+ struct child_process cp = CHILD_PROCESS_INIT;
+
+ /*
+ * Update-index is very complicated and may need to have a public
+ * function exposed in order to remove this forking.
+ */
+ cp.git_cmd = 1;
+ argv_array_pushl(&cp.args, "update-index", "--add", "--stdin", NULL);
+ return pipe_command(&cp, out->buf, out->len, NULL, 0, NULL, 0);
+}
+
+static int restore_untracked(struct object_id *u_tree)
+{
+ int res;
+ struct child_process cp = CHILD_PROCESS_INIT;
+
+ /*
+ * We need to run restore files from a given index, but without
+ * affecting the current index, so we use GIT_INDEX_FILE with
+ * run_command to fork processes that will not interfere.
+ */
+ cp.git_cmd = 1;
+ argv_array_push(&cp.args, "read-tree");
+ argv_array_push(&cp.args, oid_to_hex(u_tree));
+ argv_array_pushf(&cp.env_array, "GIT_INDEX_FILE=%s",
+ stash_index_path.buf);
+ if (run_command(&cp)) {
+ remove_path(stash_index_path.buf);
+ return -1;
+ }
+
+ child_process_init(&cp);
+ cp.git_cmd = 1;
+ argv_array_pushl(&cp.args, "checkout-index", "--all", NULL);
+ argv_array_pushf(&cp.env_array, "GIT_INDEX_FILE=%s",
+ stash_index_path.buf);
+
+ res = run_command(&cp);
+ remove_path(stash_index_path.buf);
+ return res;
+}
+
+static int do_apply_stash(const char *prefix, struct stash_info *info,
+ int index, int quiet)
+{
+ int ret;
+ int has_index = index;
+ struct merge_options o;
+ struct object_id c_tree;
+ struct object_id index_tree;
+ struct commit *result;
+ const struct object_id *bases[1];
+
+ read_cache_preload(NULL);
+ if (refresh_cache(REFRESH_QUIET))
+ return -1;
+
+ if (write_cache_as_tree(&c_tree, 0, NULL))
+ return error(_("cannot apply a stash in the middle of a merge"));
+
+ if (index) {
+ if (oideq(&info->b_tree, &info->i_tree) ||
+ oideq(&c_tree, &info->i_tree)) {
+ has_index = 0;
+ } else {
+ struct strbuf out = STRBUF_INIT;
+
+ if (diff_tree_binary(&out, &info->w_commit)) {
+ strbuf_release(&out);
+ return error(_("could not generate diff %s^!."),
+ oid_to_hex(&info->w_commit));
+ }
+
+ ret = apply_cached(&out);
+ strbuf_release(&out);
+ if (ret)
+ return error(_("conflicts in index."
+ "Try without --index."));
+
+ discard_cache();
+ read_cache();
+ if (write_cache_as_tree(&index_tree, 0, NULL))
+ return error(_("could not save index tree"));
+
+ reset_head();
+ }
+ }
+
+ if (info->has_u && restore_untracked(&info->u_tree))
+ return error(_("could not restore untracked files from stash"));
+
+ init_merge_options(&o);
+
+ o.branch1 = "Updated upstream";
+ o.branch2 = "Stashed changes";
+
+ if (oideq(&info->b_tree, &c_tree))
+ o.branch1 = "Version stash was based on";
+
+ if (quiet)
+ o.verbosity = 0;
+
+ if (o.verbosity >= 3)
+ printf_ln(_("Merging %s with %s"), o.branch1, o.branch2);
+
+ bases[0] = &info->b_tree;
+
+ ret = merge_recursive_generic(&o, &c_tree, &info->w_tree, 1, bases,
+ &result);
+ if (ret) {
+ rerere(0);
+
+ if (index)
+ fprintf_ln(stderr, _("Index was not unstashed."));
+
+ return ret;
+ }
+
+ if (has_index) {
+ if (reset_tree(&index_tree, 0, 0))
+ return -1;
+ } else {
+ struct strbuf out = STRBUF_INIT;
+
+ if (get_newly_staged(&out, &c_tree)) {
+ strbuf_release(&out);
+ return -1;
+ }
+
+ if (reset_tree(&c_tree, 0, 1)) {
+ strbuf_release(&out);
+ return -1;
+ }
+
+ ret = update_index(&out);
+ strbuf_release(&out);
+ if (ret)
+ return -1;
+
+ discard_cache();
+ }
+
+ if (quiet) {
+ if (refresh_cache(REFRESH_QUIET))
+ warning("could not refresh index");
+ } else {
+ struct child_process cp = CHILD_PROCESS_INIT;
+
+ /*
+ * Status is quite simple and could be replaced with calls to
+ * wt_status in the future, but it adds complexities which may
+ * require more tests.
+ */
+ cp.git_cmd = 1;
+ cp.dir = prefix;
+ argv_array_push(&cp.args, "status");
+ run_command(&cp);
+ }
+
+ return 0;
+}
+
+static int apply_stash(int argc, const char **argv, const char *prefix)
+{
+ int ret;
+ int quiet = 0;
+ int index = 0;
+ struct stash_info info;
+ struct option options[] = {
+ OPT__QUIET(&quiet, N_("be quiet, only report errors")),
+ OPT_BOOL(0, "index", &index,
+ N_("attempt to recreate the index")),
+ OPT_END()
+ };
+
+ argc = parse_options(argc, argv, prefix, options,
+ git_stash_helper_apply_usage, 0);
+
+ if (get_stash_info(&info, argc, argv))
+ return -1;
+
+ ret = do_apply_stash(prefix, &info, index, quiet);
+ free_stash_info(&info);
+ return ret;
+}
+
+int cmd_stash__helper(int argc, const char **argv, const char *prefix)
+{
+ pid_t pid = getpid();
+ const char *index_file;
+
+ struct option options[] = {
+ OPT_END()
+ };
+
+ git_config(git_default_config, NULL);
+
+ argc = parse_options(argc, argv, prefix, options, git_stash_helper_usage,
+ PARSE_OPT_KEEP_UNKNOWN | PARSE_OPT_KEEP_DASHDASH);
+
+ index_file = get_index_file();
+ strbuf_addf(&stash_index_path, "%s.stash.%" PRIuMAX, index_file,
+ (uintmax_t)pid);
+
+ if (argc < 1)
+ usage_with_options(git_stash_helper_usage, options);
+ if (!strcmp(argv[0], "apply"))
+ return !!apply_stash(argc, argv, prefix);
+
+ usage_msg_opt(xstrfmt(_("unknown subcommand: %s"), argv[0]),
+ git_stash_helper_usage, options);
+}