git/wt-status-deserialize.c

#include "git-compat-util.h"
#include "environment.h"
#include "hex.h"
#include "hash.h"
#include "cache.h"
#include "wt-status.h"
#include "pkt-line.h"
#include "trace.h"
#include "trace2.h"

static void set_deserialize_reject_reason(const char *reason)
{
	trace2_data_string("status", the_repository, "deserialize/reject",
			   reason);
}

int wt_status_deserialize_access(const char *path, int mode)
{
	int a = access(path, mode);

	if (a != 0)
		set_deserialize_reject_reason("status-cache/access");

	return a;
}

static struct trace_key trace_deserialize = TRACE_KEY_INIT(DESERIALIZE);

enum deserialize_parse_strategy {
	DESERIALIZE_STRATEGY_AS_IS,
	DESERIALIZE_STRATEGY_SKIP,
	DESERIALIZE_STRATEGY_NORMAL,
	DESERIALIZE_STRATEGY_ALL
};

static int check_path_contains(const char *out, int out_len, const char *in, int in_len)
{
	return (out_len > 0 &&
		out_len < in_len &&
		(out[out_len - 1] == '/') &&
		!memcmp(out, in, out_len));
}

static const char *my_packet_read_line(int fd, int *line_len)
{
	static char buf[LARGE_PACKET_MAX];

	*line_len = packet_read(fd, buf, sizeof(buf),
				PACKET_READ_CHOMP_NEWLINE |
				PACKET_READ_GENTLE_ON_EOF);
	return (*line_len > 0) ? buf : NULL;
}

/*
 * mtime_reported contains the mtime of the index when the
 * serialization snapshot was computed.
 *
 * mtime_observed_on_disk contains the mtime of the index now.
 *
 * If these 2 times are different, then the .git/index has
 * changed since the serialization cache was created and we
 * must reject the cache because anything could have changed.
 *
 * If they are the same, we continue trying to use the cache.
 */
static int my_validate_index(const struct cache_time *mtime_reported)
{
	const char *path = get_index_file();
	struct stat st;
	struct cache_time mtime_observed_on_disk;

	if (lstat(path, &st)) {
		set_deserialize_reject_reason("index/not-found");
		trace_printf_key(&trace_deserialize, "could not stat index");
		return DESERIALIZE_ERR;
	}
	mtime_observed_on_disk.sec = st.st_mtime;
	mtime_observed_on_disk.nsec = ST_MTIME_NSEC(st);
	if ((mtime_observed_on_disk.sec != mtime_reported->sec) ||
	    (mtime_observed_on_disk.nsec != mtime_reported->nsec)) {
		set_deserialize_reject_reason("index/mtime-changed");
		trace_printf_key(&trace_deserialize,
				 "index mtime changed [des %d %d][obs %d %d]",
			     mtime_reported->sec, mtime_reported->nsec,
			     mtime_observed_on_disk.sec, mtime_observed_on_disk.nsec);
		return DESERIALIZE_ERR;
	}

	return DESERIALIZE_OK;
}

/*
 * Use the given key and exclude pathname to compute a serialization header
 * reflecting the current contents on disk.  See if that matches the value
 * computed for this key when the cache was written.  Reject the cache if
 * anything has changed.
 */
static int my_validate_excludes(const char *path, const char *key, const char *line)
{
	struct strbuf sb = STRBUF_INIT;
	int r;

	wt_serialize_compute_exclude_header(&sb, key, path);

	r = (strcmp(line, sb.buf) ? DESERIALIZE_ERR : DESERIALIZE_OK);

	if (r == DESERIALIZE_ERR) {
		set_deserialize_reject_reason("excludes/changed");
		trace_printf_key(&trace_deserialize,
				 "%s changed [cached '%s'][observed '%s']",
				 key, line, sb.buf);
	}

	strbuf_release(&sb);
	return r;
}

static int my_parse_core_excludes(const char *line)
{
	/*
	 * In dir.c:setup_standard_excludes() they use either the value of
	 * the "core.excludefile" variable (stored in the global "excludes_file"
	 * variable) -or- the default value "$XDG_HOME/git/ignore".  This is done
	 * during wt_status_collect_untracked() which we are hoping to not call.
	 *
	 * Fake the setup here.
	 */

	if (excludes_file) {
		return my_validate_excludes(excludes_file, "core_excludes", line);
	} else {
		char *path = xdg_config_home("ignore");
		int r = my_validate_excludes(path, "core_excludes", line);
		free(path);
		return r;
	}
}

static int my_parse_repo_excludes(const char *line)
{
	char *path = git_pathdup("info/exclude");
	int r = my_validate_excludes(path, "repo_excludes", line);
	free(path);

	return r;
}

static int wt_deserialize_v1_header(struct wt_status *s, int fd)
{
	struct cache_time index_mtime;
	int line_len, nr_fields;
	const char *line;
	const char *arg;
	int have_required_index_mtime = 0;
	int have_required_core_excludes = 0;
	int have_required_repo_excludes = 0;

	/*
	 * parse header lines up to the first flush packet.
	 */
	while ((line = my_packet_read_line(fd, &line_len))) {

		if (skip_prefix(line, "index_mtime ", &arg)) {
			nr_fields = sscanf(arg, "%u %u",
					   &index_mtime.sec,
					   &index_mtime.nsec);
			if (nr_fields != 2) {
				set_deserialize_reject_reason("v1-header/invalid-index-mtime");
				trace_printf_key(&trace_deserialize, "invalid index_mtime (%d) '%s'",
					     nr_fields, line);
				return DESERIALIZE_ERR;
			}
			have_required_index_mtime = 1;
			continue;
		}

		if (skip_prefix(line, "core_excludes ", &arg)) {
			if (my_parse_core_excludes(line) != DESERIALIZE_OK)
				return DESERIALIZE_ERR;
			have_required_core_excludes = 1;
			continue;
		}
		if (skip_prefix(line, "repo_excludes ", &arg)) {
			if (my_parse_repo_excludes(line) != DESERIALIZE_OK)
				return DESERIALIZE_ERR;
			have_required_repo_excludes = 1;
			continue;
		}

		if (skip_prefix(line, "is_initial ", &arg)) {
			s->is_initial = (int)strtol(arg, NULL, 10);
			continue;
		}
		if (skip_prefix(line, "branch ", &arg)) {
			s->branch = xstrdup(arg);
			continue;
		}
		if (skip_prefix(line, "reference ", &arg)) {
			s->reference = xstrdup(arg);
			continue;
		}
		/* pathspec */
		/* verbose */
		/* amend */
		if (skip_prefix(line, "whence ", &arg)) {
			s->whence = (int)strtol(arg, NULL, 10);
			continue;
		}
		/* nowarn */
		/* use_color */
		/* no_gettext */
		/* display_comment_prefix */
		/* relative_paths */
		/* submodule_summary */
		if (skip_prefix(line, "show_ignored_mode ", &arg)) {
			s->show_ignored_mode = (int)strtol(arg, NULL, 10);
			continue;
		}
		if (skip_prefix(line, "show_untracked_files ", &arg)) {
			s->show_untracked_files = (int)strtol(arg, NULL, 10);
			continue;
		}
		if (skip_prefix(line, "ignore_submodule_arg ", &arg)) {
			s->ignore_submodule_arg = xstrdup(arg);
			continue;
		}
		/* color_palette */
		/* colopts */
		/* null_termination */
		/* commit_template */
		/* show_branch */
		/* show_stash */
		if (skip_prefix(line, "hints ", &arg)) {
			s->hints = (int)strtol(arg, NULL, 10);
			continue;
		}
		if (skip_prefix(line, "detect_rename ", &arg)) {
			s->detect_rename = (int)strtol(arg, NULL, 10);
			continue;
		}
		if (skip_prefix(line, "rename_score ", &arg)) {
			s->rename_score = (int)strtol(arg, NULL, 10);
			continue;
		}
		if (skip_prefix(line, "rename_limit ", &arg)) {
			s->rename_limit = (int)strtol(arg, NULL, 10);
			continue;
		}
		/* status_format */
		if (skip_prefix(line, "sha1_commit ", &arg)) {
			if (get_oid_hex(arg, &s->oid_commit)) {
				set_deserialize_reject_reason("v1-header/invalid-commit-sha");
				trace_printf_key(&trace_deserialize, "invalid sha1_commit");
				return DESERIALIZE_ERR;
			}
			continue;
		}
		if (skip_prefix(line, "committable ", &arg)) {
			s->committable = (int)strtol(arg, NULL, 10);
			continue;
		}
		if (skip_prefix(line, "workdir_dirty ", &arg)) {
			s->workdir_dirty = (int)strtol(arg, NULL, 10);
			continue;
		}
		/* prefix */

		set_deserialize_reject_reason("v1-header/unexpected-line");
		trace_printf_key(&trace_deserialize, "unexpected line '%s'", line);
		return DESERIALIZE_ERR;
	}

	if (!have_required_index_mtime) {
		set_deserialize_reject_reason("v1-header/missing-index-mtime");
		trace_printf_key(&trace_deserialize, "missing '%s'", "index_mtime");
		return DESERIALIZE_ERR;
	}
	if (!have_required_core_excludes) {
		set_deserialize_reject_reason("v1-header/missing-core-excludes");
		trace_printf_key(&trace_deserialize, "missing '%s'", "core_excludes");
		return DESERIALIZE_ERR;
	}
	if (!have_required_repo_excludes) {
		set_deserialize_reject_reason("v1-header/missing-repo-excludes");
		trace_printf_key(&trace_deserialize, "missing '%s'", "repo_excludes");
		return DESERIALIZE_ERR;
	}

	return my_validate_index(&index_mtime);
}

/*
 * Build a string-list of (count) <changed-item> lines from the input.
 */
static int wt_deserialize_v1_changed_items(const struct wt_status *cmd_s,
					   struct wt_status *s, int fd, int count)
{
	struct wt_status_serialize_data *sd;
	char *p;
	int line_len;
	const char *line;
	struct string_list_item *item;

	memset(&s->change, 0, sizeof(s->change));
	s->change.strdup_strings = 1;

	/*
	 * <wt_status_change_data_fields>+
	 * <flush>
	 *
	 * <fixed_part><path> NUL [<head_path>] NUL
	 */
	while ((line = my_packet_read_line(fd, &line_len))) {
		struct wt_status_change_data *d = xcalloc(1, sizeof(*d));
		sd = (struct wt_status_serialize_data *)line;

		d->worktree_status = ntohl(sd->fixed.worktree_status);
		d->index_status = ntohl(sd->fixed.index_status);
		d->stagemask = ntohl(sd->fixed.stagemask);
		d->rename_status = ntohl(sd->fixed.rename_status);
		d->rename_score = ntohl(sd->fixed.rename_score);
		d->mode_head = ntohl(sd->fixed.mode_head);
		d->mode_index = ntohl(sd->fixed.mode_index);
		d->mode_worktree = ntohl(sd->fixed.mode_worktree);
		d->dirty_submodule = ntohl(sd->fixed.dirty_submodule);
		d->new_submodule_commits = ntohl(sd->fixed.new_submodule_commits);
		oidcpy(&d->oid_head, &sd->fixed.oid_head);
		oidcpy(&d->oid_index, &sd->fixed.oid_index);

		p = sd->variant;
		item = string_list_append(&s->change, p);
		p += strlen(p) + 1;
		if (*p)
			d->rename_source = xstrdup(p);
		item->util = d;

		trace_printf_key(
			&trace_deserialize,
			"change: %d %d %d %d %d %o %o %o %d %d %s %s '%s' '%s'",
			d->worktree_status,
			d->index_status,
			d->stagemask,
			d->rename_status,
			d->rename_score,
			d->mode_head,
			d->mode_index,
			d->mode_worktree,
			d->dirty_submodule,
			d->new_submodule_commits,
			oid_to_hex(&d->oid_head),
			oid_to_hex(&d->oid_index),
			item->string,
			(d->rename_source ? d->rename_source : ""));

		if (d->stagemask &&
		    cmd_s->status_format == STATUS_FORMAT_PORCELAIN_V2) {
			/*
			 * We have an unresolved conflict and the user wants
			 * to see porcelain V2 output.  The cached status data
			 * does not contain enough information for V2 (because
			 * the main status computation does not capture it).
			 * We only get a single change record for the file with
			 * a single SHA -- we don't get the stage [123] mode
			 * and SHA data.  The V2 detail-line print code looks
			 * up this information directly from the index.  The
			 * whole point of this serialization cache is to avoid
			 * reading the index, so the V2 print code gets zeros.
			 * So we reject the status cache and let the fallback
			 * code run.
			 */
			set_deserialize_reject_reason("v1-data/unmerged");
			trace_printf_key(
				&trace_deserialize,
				"reject: V2 format and umerged file: %s",
				item->string);
			return DESERIALIZE_ERR;
		}
	}

	return DESERIALIZE_OK;
}

static int wt_deserialize_v1_untracked_items(struct wt_status *s,
					     int fd,
					     int count,
					     enum deserialize_parse_strategy strategy)
{
	int line_len;
	const char *line;
	char *out = NULL;
	int out_len = 0;

	memset(&s->untracked, 0, sizeof(s->untracked));
	s->untracked.strdup_strings = 1;

	/*
	 * <pathname>+
	 * <flush>
	 */
	while ((line = my_packet_read_line(fd, &line_len))) {
		if (strategy == DESERIALIZE_STRATEGY_AS_IS)
			string_list_append(&s->untracked, line);
		if (strategy == DESERIALIZE_STRATEGY_SKIP)
			continue;
		if (strategy == DESERIALIZE_STRATEGY_NORMAL) {

			/* Only add "normal" entries to list */
			if (out &&
				check_path_contains(out, out_len, line, line_len)) {
				continue;
			}
			else {
				out = string_list_append(&s->untracked, line)->string;
				out_len = line_len;
			}
		}
		if (strategy == DESERIALIZE_STRATEGY_ALL) {
			/* Only add "all" entries to list */
			if (line[line_len - 1] != '/')
				string_list_append(&s->untracked, line);
		}
	}

	return DESERIALIZE_OK;
}

static int wt_deserialize_v1_ignored_items(struct wt_status *s,
					   int fd,
					   int count,
					   enum deserialize_parse_strategy strategy)
{
	int line_len;
	const char *line;

	memset(&s->ignored, 0, sizeof(s->ignored));
	s->ignored.strdup_strings = 1;

	/*
	 * <pathname>+
	 * <flush>
	 */
	while ((line = my_packet_read_line(fd, &line_len))) {
		if (strategy == DESERIALIZE_STRATEGY_AS_IS)
			string_list_append(&s->ignored, line);
		else
			continue;
	}

	return DESERIALIZE_OK;
}

static int validate_untracked_files_arg(enum untracked_status_type cmd,
					enum untracked_status_type *des,
					enum deserialize_parse_strategy *strategy)
{
	*strategy = DESERIALIZE_STRATEGY_AS_IS;

	if (cmd == *des) {
		*strategy = DESERIALIZE_STRATEGY_AS_IS;
	} else if (cmd == SHOW_NO_UNTRACKED_FILES) {
		*strategy = DESERIALIZE_STRATEGY_SKIP;
		*des = cmd;
	} else if (*des == SHOW_COMPLETE_UNTRACKED_FILES) {
		if (cmd == SHOW_ALL_UNTRACKED_FILES) {
			*strategy = DESERIALIZE_STRATEGY_ALL;
			*des = cmd;
		} else if (cmd == SHOW_NORMAL_UNTRACKED_FILES) {
			*strategy = DESERIALIZE_STRATEGY_NORMAL;
			*des = cmd;
		}
	} else {
		return DESERIALIZE_ERR;
	}

	return DESERIALIZE_OK;
}

static int validate_ignored_files_arg(enum show_ignored_type cmd,
				      enum show_ignored_type des,
				      enum deserialize_parse_strategy *strategy)
{
	*strategy = DESERIALIZE_STRATEGY_AS_IS;

	if (cmd == SHOW_NO_IGNORED) {
		*strategy = DESERIALIZE_STRATEGY_SKIP;
	}
	else if (cmd != des) {
		return DESERIALIZE_ERR;
	}

	return DESERIALIZE_OK;
}

static int wt_deserialize_v1(const struct wt_status *cmd_s, struct wt_status *s, int fd)
{
	int line_len;
	const char *line;
	const char *arg;
	int nr_changed = 0;
	int nr_untracked = 0;
	int nr_ignored = 0;

	enum deserialize_parse_strategy ignored_strategy = DESERIALIZE_STRATEGY_AS_IS, untracked_strategy = DESERIALIZE_STRATEGY_AS_IS;

	if (wt_deserialize_v1_header(s, fd) == DESERIALIZE_ERR)
		return DESERIALIZE_ERR;

	/*
	 * We now have the header parsed. Look at the command args (as passed in), and see how to parse
	 * the serialized data
	*/
	if (validate_untracked_files_arg(cmd_s->show_untracked_files, &s->show_untracked_files, &untracked_strategy)) {
		set_deserialize_reject_reason("args/untracked-files");
		trace_printf_key(&trace_deserialize, "reject: show_untracked_file: command: %d, serialized : %d",
				cmd_s->show_untracked_files,
				s->show_untracked_files);
		return DESERIALIZE_ERR;
	}

	if (validate_ignored_files_arg(cmd_s->show_ignored_mode, s->show_ignored_mode, &ignored_strategy)) {
		set_deserialize_reject_reason("args/ignored-mode");
		trace_printf_key(&trace_deserialize, "reject: show_ignored_mode: command: %d, serialized: %d",
				cmd_s->show_ignored_mode,
				s->show_ignored_mode);
		return DESERIALIZE_ERR;
	}

	/*
	 * [<changed-header> [<changed-item>+] <flush>]
	 * [<untracked-header> [<untracked-item>+] <flush>]
	 * [<ignored-header> [<ignored-item>+] <flush>]
	 */
	while ((line = my_packet_read_line(fd, &line_len))) {
		if (skip_prefix(line, "changed ", &arg)) {
			nr_changed = (int)strtol(arg, NULL, 10);
			if (wt_deserialize_v1_changed_items(cmd_s, s, fd, nr_changed)
			    == DESERIALIZE_ERR)
				return DESERIALIZE_ERR;
			continue;
		}
		if (skip_prefix(line, "untracked ", &arg)) {
			nr_untracked = (int)strtol(arg, NULL, 10);
			if (wt_deserialize_v1_untracked_items(s, fd, nr_untracked, untracked_strategy)
			    == DESERIALIZE_ERR)
				return DESERIALIZE_ERR;
			continue;
		}
		if (skip_prefix(line, "ignored ", &arg)) {
			nr_ignored = (int)strtol(arg, NULL, 10);
			if (wt_deserialize_v1_ignored_items(s, fd, nr_ignored, ignored_strategy)
			    == DESERIALIZE_ERR)
				return DESERIALIZE_ERR;
			continue;
		}
		set_deserialize_reject_reason("v1-data/unexpected-line");
		trace_printf_key(&trace_deserialize, "unexpected line '%s'", line);
		return DESERIALIZE_ERR;
	}

	return DESERIALIZE_OK;
}

static int wt_deserialize_parse(const struct wt_status *cmd_s, struct wt_status *s, int fd)
{
	int line_len;
	const char *line;
	const char *arg;

	memset(s, 0, sizeof(*s));

	if ((line = my_packet_read_line(fd, &line_len)) &&
	    (skip_prefix(line, "version ", &arg))) {
		int version = (int)strtol(arg, NULL, 10);
		if (version == 1)
			return wt_deserialize_v1(cmd_s, s, fd);
	}
	set_deserialize_reject_reason("status-cache/unsupported-version");
	trace_printf_key(&trace_deserialize, "missing/unsupported version");
	return DESERIALIZE_ERR;
}

static inline int my_strcmp_null(const char *a, const char *b)
{
	const char *alt_a = (a) ? a : "";
	const char *alt_b = (b) ? b : "";

	return strcmp(alt_a, alt_b);
}

static int wt_deserialize_fd(const struct wt_status *cmd_s, struct wt_status *des_s, int fd)
{
	memset(des_s, 0, sizeof(*des_s));

	/*
	 * Check the path spec on the current command
	 */
	if (cmd_s->pathspec.nr > 1) {
		set_deserialize_reject_reason("args/multiple-pathspecs");
		trace_printf_key(&trace_deserialize, "reject: multiple pathspecs");
		return DESERIALIZE_ERR;
	}

	/*
	 * If we have a pathspec, but it maches the root (e.g. no filtering)
	 * then this is OK.
	 */
	if (cmd_s->pathspec.nr == 1 &&
		my_strcmp_null(cmd_s->pathspec.items[0].match, "")) {
		set_deserialize_reject_reason("args/root-pathspec");
		trace_printf_key(&trace_deserialize, "reject: pathspec");
		return DESERIALIZE_ERR;
	}

	/*
	 * Deserialize cached status
	 */
	if (wt_deserialize_parse(cmd_s, des_s, fd) == DESERIALIZE_ERR)
		return DESERIALIZE_ERR;

	/*
	 * Compare fields in cmd_s with those observed in des_s and
	 * complain if they are incompatible (such as different "-u"
	 * or "--ignored" settings).
	 */
	if (cmd_s->is_initial != des_s->is_initial) {
		set_deserialize_reject_reason("args/is-initial-changed");
		trace_printf_key(&trace_deserialize, "reject: is_initial");
		return DESERIALIZE_ERR;
	}
	if (my_strcmp_null(cmd_s->branch, des_s->branch)) {
		set_deserialize_reject_reason("args/branch-changed");
		trace_printf_key(&trace_deserialize, "reject: branch");
		return DESERIALIZE_ERR;
	}
	if (my_strcmp_null(cmd_s->reference, des_s->reference)) {
		set_deserialize_reject_reason("args/reference-changed");
		trace_printf_key(&trace_deserialize, "reject: reference");
		return DESERIALIZE_ERR;
	}
	/* verbose */
	/* amend */
	if (cmd_s->whence != des_s->whence) {
		set_deserialize_reject_reason("args/whence-changed");
		trace_printf_key(&trace_deserialize, "reject: whence");
		return DESERIALIZE_ERR;
	}
	/* nowarn */
	/* use_color */
	/* no_gettext */
	/* display_comment_prefix */
	/* relative_paths */
	/* submodule_summary */

	/* show_ignored_files - already validated */
	/* show_untrackes_files - already validated */

	/*
	 * Submodules are not supported by status serialization.
	 * The status will not be serialized if it contains submodules,
	 * and so this check is not needed.
	 *
	 * if (my_strcmp_null(cmd_s->ignore_submodule_arg, des_s->ignore_submodule_arg)) {
	 *	trace_printf_key(&trace_deserialize, "reject: ignore_submodule_arg");
	 * 	return DESERIALIZE_ERR;
	 * }
	 */

	/* color_palette */
	/* colopts */
	/* null_termination */
	/* commit_template */
	/* show_branch */
	/* show_stash */
	/* hints */
	/* ahead_behind_flags */
	if (cmd_s->detect_rename != des_s->detect_rename) {
		set_deserialize_reject_reason("args/detect-rename-changed");
		trace_printf_key(&trace_deserialize, "reject: detect_rename");
		return DESERIALIZE_ERR;
	}
	if (cmd_s->rename_score != des_s->rename_score) {
		set_deserialize_reject_reason("args/rename-score-changed");
		trace_printf_key(&trace_deserialize, "reject: rename_score");
		return DESERIALIZE_ERR;
	}
	if (cmd_s->rename_limit != des_s->rename_limit) {
		set_deserialize_reject_reason("args/rename-limit-changed");
		trace_printf_key(&trace_deserialize, "reject: rename_limit");
		return DESERIALIZE_ERR;
	}
	/* status_format */
	if (!oideq(&cmd_s->oid_commit, &des_s->oid_commit)) {
		set_deserialize_reject_reason("args/commit-changed");
		trace_printf_key(&trace_deserialize, "reject: sha1_commit");
		return DESERIALIZE_ERR;
	}

	/*
	 * Copy over display-related fields from the current command.
	 */
	des_s->repo = cmd_s->repo;
	des_s->verbose = cmd_s->verbose;
	/* amend */
	/* whence */
	des_s->nowarn = cmd_s->nowarn;
	des_s->use_color = cmd_s->use_color;
	des_s->no_gettext = cmd_s->no_gettext;
	des_s->display_comment_prefix = cmd_s->display_comment_prefix;
	des_s->relative_paths = cmd_s->relative_paths;
	des_s->submodule_summary = cmd_s->submodule_summary;
	memcpy(des_s->color_palette, cmd_s->color_palette,
	       sizeof(char)*WT_STATUS_MAXSLOT*COLOR_MAXLEN);
	des_s->colopts = cmd_s->colopts;
	des_s->null_termination = cmd_s->null_termination;
	/* commit_template */
	des_s->show_branch = cmd_s->show_branch;
	des_s->show_stash = cmd_s->show_stash;
	/* hints */
	des_s->ahead_behind_flags = cmd_s->ahead_behind_flags;
	des_s->status_format = cmd_s->status_format;
	des_s->fp = cmd_s->fp;
	if (cmd_s->prefix && *cmd_s->prefix)
		des_s->prefix = xstrdup(cmd_s->prefix);

	return DESERIALIZE_OK;
}

static struct cache_time deserialize_prev_mtime = { 0, 0 };

static int try_deserialize_read_from_file_1(const struct wt_status *cmd_s,
					    const char *path,
					    struct wt_status *des_s)
{
	struct stat st;
	int result;
	int fd;

	/*
	 * If we are spinning waiting for the status cache to become
	 * valid, skip re-reading it if the mtime has not changed
	 * since the last time we read it.
	 */
	if (lstat(path, &st)) {
		trace_printf_key(&trace_deserialize,
				 "could not lstat '%s'", path);
		return DESERIALIZE_ERR;
	}
	if (st.st_mtime == deserialize_prev_mtime.sec &&
	    ST_MTIME_NSEC(st) == deserialize_prev_mtime.nsec) {
		trace_printf_key(&trace_deserialize,
				 "mtime has not changed '%s'", path);
		return DESERIALIZE_ERR;
	}

	fd = xopen(path, O_RDONLY);
	if (fd == -1) {
		trace_printf_key(&trace_deserialize,
				 "could not read '%s'", path);
		return DESERIALIZE_ERR;
	}

	deserialize_prev_mtime.sec = st.st_mtime;
	deserialize_prev_mtime.nsec = ST_MTIME_NSEC(st);

	trace_printf_key(&trace_deserialize,
			 "reading serialization file (%d %d) '%s'",
			 deserialize_prev_mtime.sec,
			 deserialize_prev_mtime.nsec,
			 path);

	result = wt_deserialize_fd(cmd_s, des_s, fd);
	close(fd);

	return result;
}

static int try_deserialize_read_from_file(const struct wt_status *cmd_s,
					  const char *path,
					  enum wt_status_deserialize_wait dw,
					  struct wt_status *des_s)
{
	int k = 0;
	int limit;
	int result = DESERIALIZE_ERR;

	/*
	 * For "fail" or "no", try exactly once to read the status cache.
	 * Return an error if the file is stale.
	 */
	if (dw == DESERIALIZE_WAIT__FAIL || dw == DESERIALIZE_WAIT__NO) {
		result = try_deserialize_read_from_file_1(cmd_s, path, des_s);
		goto done;
	}

	/*
	 * Wait for the status cache file to refresh.  Wait duration can
	 * be in tenths of a second or unlimited.  Poll every 100ms.
	 */
	if (dw == DESERIALIZE_WAIT__BLOCK) {
		/*
		 * Convert "unlimited" to 1 day.
		 */
		limit = 10 * 60 * 60 * 24;
	} else {
		/* spin for dw tenths of a second */
		limit = dw;
	}
	for (k = 0; k < limit; k++) {
		result = try_deserialize_read_from_file_1(
			cmd_s, path, des_s);

		if (result == DESERIALIZE_OK)
			break;

		sleep_millisec(100);
	}

done:
	trace2_data_string("status", the_repository, "deserialize/path", path);
	trace2_data_intmax("status", the_repository, "deserialize/polled", k);
	trace2_data_string("status", the_repository, "deserialize/result",
			   ((result == DESERIALIZE_OK) ? "ok" : "reject"));

	trace_printf_key(&trace_deserialize,
			 "wait polled=%d result=%d '%s'",
			 k, result, path);
	return result;
}

/*
 * Read raw serialized status data from the given file (or STDIN).
 *
 * Verify that the args specified in the current command
 * are compatible with the deserialized data (such as "-uno").
 *
 * Copy display-related fields from the current command
 * into the deserialized data (so that the user can request
 * long or short as they please).
 *
 * Print status report using cached data.
 */
int wt_status_deserialize(const struct wt_status *cmd_s,
			  const char *path,
			  enum wt_status_deserialize_wait dw)
{
	struct wt_status des_s;
	int result;

	trace2_region_enter("status", "deserialize", the_repository);

	if (path && *path && strcmp(path, "0")) {
		result = try_deserialize_read_from_file(cmd_s, path, dw, &des_s);
	} else {
		trace_printf_key(&trace_deserialize, "reading stdin");

		/*
		 * Read status cache data from stdin.  Ignore the deserialize-wait
		 * term, since we cannot read stdin multiple times.
		 */
		result = wt_deserialize_fd(cmd_s, &des_s, 0);

		trace2_data_string("status", the_repository, "deserialize/path", "STDIN");
		trace2_data_string("status", the_repository, "deserialize/result",
				   ((result == DESERIALIZE_OK) ? "ok" : "reject"));
	}

	trace2_region_leave("status", "deserialize", the_repository);

	if (result == DESERIALIZE_OK) {
		wt_status_get_state(cmd_s->repo, &des_s.state, des_s.branch &&
				    !strcmp(des_s.branch, "HEAD"));
		wt_status_print(&des_s);
	}

	return result;
}