Squashed 'third_party/git/' content from commit cb71568594

git-subtree-dir: third_party/git
git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7

1 files changed, 2503 insertions, 0 deletions

diff --git a/ref-filter.c b/ref-filter.c
new file mode 100644
index 000000000000..f27cfc8c3e35
--- /dev/null
+++ b/ref-filter.c
@@ -0,0 +1,2503 @@
+#include "builtin.h"
+#include "cache.h"
+#include "parse-options.h"
+#include "refs.h"
+#include "wildmatch.h"
+#include "object-store.h"
+#include "repository.h"
+#include "commit.h"
+#include "remote.h"
+#include "color.h"
+#include "tag.h"
+#include "quote.h"
+#include "ref-filter.h"
+#include "revision.h"
+#include "utf8.h"
+#include "git-compat-util.h"
+#include "version.h"
+#include "trailer.h"
+#include "wt-status.h"
+#include "commit-slab.h"
+#include "commit-graph.h"
+#include "commit-reach.h"
+#include "worktree.h"
+#include "hashmap.h"
+#include "argv-array.h"
+
+static struct ref_msg {
+	const char *gone;
+	const char *ahead;
+	const char *behind;
+	const char *ahead_behind;
+} msgs = {
+	 /* Untranslated plumbing messages: */
+	"gone",
+	"ahead %d",
+	"behind %d",
+	"ahead %d, behind %d"
+};
+
+void setup_ref_filter_porcelain_msg(void)
+{
+	msgs.gone = _("gone");
+	msgs.ahead = _("ahead %d");
+	msgs.behind = _("behind %d");
+	msgs.ahead_behind = _("ahead %d, behind %d");
+}
+
+typedef enum { FIELD_STR, FIELD_ULONG, FIELD_TIME } cmp_type;
+typedef enum { COMPARE_EQUAL, COMPARE_UNEQUAL, COMPARE_NONE } cmp_status;
+typedef enum { SOURCE_NONE = 0, SOURCE_OBJ, SOURCE_OTHER } info_source;
+
+struct align {
+	align_type position;
+	unsigned int width;
+};
+
+struct if_then_else {
+	cmp_status cmp_status;
+	const char *str;
+	unsigned int then_atom_seen : 1,
+		else_atom_seen : 1,
+		condition_satisfied : 1;
+};
+
+struct refname_atom {
+	enum { R_NORMAL, R_SHORT, R_LSTRIP, R_RSTRIP } option;
+	int lstrip, rstrip;
+};
+
+static struct expand_data {
+	struct object_id oid;
+	enum object_type type;
+	unsigned long size;
+	off_t disk_size;
+	struct object_id delta_base_oid;
+	void *content;
+
+	struct object_info info;
+} oi, oi_deref;
+
+struct ref_to_worktree_entry {
+	struct hashmap_entry ent; /* must be the first member! */
+	struct worktree *wt; /* key is wt->head_ref */
+};
+
+static int ref_to_worktree_map_cmpfnc(const void *unused_lookupdata,
+				      const void *existing_hashmap_entry_to_test,
+				      const void *key,
+				      const void *keydata_aka_refname)
+{
+	const struct ref_to_worktree_entry *e = existing_hashmap_entry_to_test;
+	const struct ref_to_worktree_entry *k = key;
+	return strcmp(e->wt->head_ref,
+		keydata_aka_refname ? keydata_aka_refname : k->wt->head_ref);
+}
+
+static struct ref_to_worktree_map {
+	struct hashmap map;
+	struct worktree **worktrees;
+} ref_to_worktree_map;
+
+/*
+ * An atom is a valid field atom listed below, possibly prefixed with
+ * a "*" to denote deref_tag().
+ *
+ * We parse given format string and sort specifiers, and make a list
+ * of properties that we need to extract out of objects.  ref_array_item
+ * structure will hold an array of values extracted that can be
+ * indexed with the "atom number", which is an index into this
+ * array.
+ */
+static struct used_atom {
+	const char *name;
+	cmp_type type;
+	info_source source;
+	union {
+		char color[COLOR_MAXLEN];
+		struct align align;
+		struct {
+			enum {
+				RR_REF, RR_TRACK, RR_TRACKSHORT, RR_REMOTE_NAME, RR_REMOTE_REF
+			} option;
+			struct refname_atom refname;
+			unsigned int nobracket : 1, push : 1, push_remote : 1;
+		} remote_ref;
+		struct {
+			enum { C_BARE, C_BODY, C_BODY_DEP, C_LINES, C_SIG, C_SUB, C_TRAILERS } option;
+			struct process_trailer_options trailer_opts;
+			unsigned int nlines;
+		} contents;
+		struct {
+			cmp_status cmp_status;
+			const char *str;
+		} if_then_else;
+		struct {
+			enum { O_FULL, O_LENGTH, O_SHORT } option;
+			unsigned int length;
+		} objectname;
+		struct refname_atom refname;
+		char *head;
+	} u;
+} *used_atom;
+static int used_atom_cnt, need_tagged, need_symref;
+
+/*
+ * Expand string, append it to strbuf *sb, then return error code ret.
+ * Allow to save few lines of code.
+ */
+static int strbuf_addf_ret(struct strbuf *sb, int ret, const char *fmt, ...)
+{
+	va_list ap;
+	va_start(ap, fmt);
+	strbuf_vaddf(sb, fmt, ap);
+	va_end(ap);
+	return ret;
+}
+
+static int color_atom_parser(const struct ref_format *format, struct used_atom *atom,
+			     const char *color_value, struct strbuf *err)
+{
+	if (!color_value)
+		return strbuf_addf_ret(err, -1, _("expected format: %%(color:<color>)"));
+	if (color_parse(color_value, atom->u.color) < 0)
+		return strbuf_addf_ret(err, -1, _("unrecognized color: %%(color:%s)"),
+				       color_value);
+	/*
+	 * We check this after we've parsed the color, which lets us complain
+	 * about syntactically bogus color names even if they won't be used.
+	 */
+	if (!want_color(format->use_color))
+		color_parse("", atom->u.color);
+	return 0;
+}
+
+static int refname_atom_parser_internal(struct refname_atom *atom, const char *arg,
+					 const char *name, struct strbuf *err)
+{
+	if (!arg)
+		atom->option = R_NORMAL;
+	else if (!strcmp(arg, "short"))
+		atom->option = R_SHORT;
+	else if (skip_prefix(arg, "lstrip=", &arg) ||
+		 skip_prefix(arg, "strip=", &arg)) {
+		atom->option = R_LSTRIP;
+		if (strtol_i(arg, 10, &atom->lstrip))
+			return strbuf_addf_ret(err, -1, _("Integer value expected refname:lstrip=%s"), arg);
+	} else if (skip_prefix(arg, "rstrip=", &arg)) {
+		atom->option = R_RSTRIP;
+		if (strtol_i(arg, 10, &atom->rstrip))
+			return strbuf_addf_ret(err, -1, _("Integer value expected refname:rstrip=%s"), arg);
+	} else
+		return strbuf_addf_ret(err, -1, _("unrecognized %%(%s) argument: %s"), name, arg);
+	return 0;
+}
+
+static int remote_ref_atom_parser(const struct ref_format *format, struct used_atom *atom,
+				  const char *arg, struct strbuf *err)
+{
+	struct string_list params = STRING_LIST_INIT_DUP;
+	int i;
+
+	if (!strcmp(atom->name, "push") || starts_with(atom->name, "push:"))
+		atom->u.remote_ref.push = 1;
+
+	if (!arg) {
+		atom->u.remote_ref.option = RR_REF;
+		return refname_atom_parser_internal(&atom->u.remote_ref.refname,
+						    arg, atom->name, err);
+	}
+
+	atom->u.remote_ref.nobracket = 0;
+	string_list_split(&params, arg, ',', -1);
+
+	for (i = 0; i < params.nr; i++) {
+		const char *s = params.items[i].string;
+
+		if (!strcmp(s, "track"))
+			atom->u.remote_ref.option = RR_TRACK;
+		else if (!strcmp(s, "trackshort"))
+			atom->u.remote_ref.option = RR_TRACKSHORT;
+		else if (!strcmp(s, "nobracket"))
+			atom->u.remote_ref.nobracket = 1;
+		else if (!strcmp(s, "remotename")) {
+			atom->u.remote_ref.option = RR_REMOTE_NAME;
+			atom->u.remote_ref.push_remote = 1;
+		} else if (!strcmp(s, "remoteref")) {
+			atom->u.remote_ref.option = RR_REMOTE_REF;
+			atom->u.remote_ref.push_remote = 1;
+		} else {
+			atom->u.remote_ref.option = RR_REF;
+			if (refname_atom_parser_internal(&atom->u.remote_ref.refname,
+							 arg, atom->name, err)) {
+				string_list_clear(&params, 0);
+				return -1;
+			}
+		}
+	}
+
+	string_list_clear(&params, 0);
+	return 0;
+}
+
+static int objecttype_atom_parser(const struct ref_format *format, struct used_atom *atom,
+				  const char *arg, struct strbuf *err)
+{
+	if (arg)
+		return strbuf_addf_ret(err, -1, _("%%(objecttype) does not take arguments"));
+	if (*atom->name == '*')
+		oi_deref.info.typep = &oi_deref.type;
+	else
+		oi.info.typep = &oi.type;
+	return 0;
+}
+
+static int objectsize_atom_parser(const struct ref_format *format, struct used_atom *atom,
+				  const char *arg, struct strbuf *err)
+{
+	if (!arg) {
+		if (*atom->name == '*')
+			oi_deref.info.sizep = &oi_deref.size;
+		else
+			oi.info.sizep = &oi.size;
+	} else if (!strcmp(arg, "disk")) {
+		if (*atom->name == '*')
+			oi_deref.info.disk_sizep = &oi_deref.disk_size;
+		else
+			oi.info.disk_sizep = &oi.disk_size;
+	} else
+		return strbuf_addf_ret(err, -1, _("unrecognized %%(objectsize) argument: %s"), arg);
+	return 0;
+}
+
+static int deltabase_atom_parser(const struct ref_format *format, struct used_atom *atom,
+				 const char *arg, struct strbuf *err)
+{
+	if (arg)
+		return strbuf_addf_ret(err, -1, _("%%(deltabase) does not take arguments"));
+	if (*atom->name == '*')
+		oi_deref.info.delta_base_sha1 = oi_deref.delta_base_oid.hash;
+	else
+		oi.info.delta_base_sha1 = oi.delta_base_oid.hash;
+	return 0;
+}
+
+static int body_atom_parser(const struct ref_format *format, struct used_atom *atom,
+			    const char *arg, struct strbuf *err)
+{
+	if (arg)
+		return strbuf_addf_ret(err, -1, _("%%(body) does not take arguments"));
+	atom->u.contents.option = C_BODY_DEP;
+	return 0;
+}
+
+static int subject_atom_parser(const struct ref_format *format, struct used_atom *atom,
+			       const char *arg, struct strbuf *err)
+{
+	if (arg)
+		return strbuf_addf_ret(err, -1, _("%%(subject) does not take arguments"));
+	atom->u.contents.option = C_SUB;
+	return 0;
+}
+
+static int trailers_atom_parser(const struct ref_format *format, struct used_atom *atom,
+				const char *arg, struct strbuf *err)
+{
+	struct string_list params = STRING_LIST_INIT_DUP;
+	int i;
+
+	atom->u.contents.trailer_opts.no_divider = 1;
+
+	if (arg) {
+		string_list_split(&params, arg, ',', -1);
+		for (i = 0; i < params.nr; i++) {
+			const char *s = params.items[i].string;
+			if (!strcmp(s, "unfold"))
+				atom->u.contents.trailer_opts.unfold = 1;
+			else if (!strcmp(s, "only"))
+				atom->u.contents.trailer_opts.only_trailers = 1;
+			else {
+				strbuf_addf(err, _("unknown %%(trailers) argument: %s"), s);
+				string_list_clear(&params, 0);
+				return -1;
+			}
+		}
+	}
+	atom->u.contents.option = C_TRAILERS;
+	string_list_clear(&params, 0);
+	return 0;
+}
+
+static int contents_atom_parser(const struct ref_format *format, struct used_atom *atom,
+				const char *arg, struct strbuf *err)
+{
+	if (!arg)
+		atom->u.contents.option = C_BARE;
+	else if (!strcmp(arg, "body"))
+		atom->u.contents.option = C_BODY;
+	else if (!strcmp(arg, "signature"))
+		atom->u.contents.option = C_SIG;
+	else if (!strcmp(arg, "subject"))
+		atom->u.contents.option = C_SUB;
+	else if (skip_prefix(arg, "trailers", &arg)) {
+		skip_prefix(arg, ":", &arg);
+		if (trailers_atom_parser(format, atom, *arg ? arg : NULL, err))
+			return -1;
+	} else if (skip_prefix(arg, "lines=", &arg)) {
+		atom->u.contents.option = C_LINES;
+		if (strtoul_ui(arg, 10, &atom->u.contents.nlines))
+			return strbuf_addf_ret(err, -1, _("positive value expected contents:lines=%s"), arg);
+	} else
+		return strbuf_addf_ret(err, -1, _("unrecognized %%(contents) argument: %s"), arg);
+	return 0;
+}
+
+static int objectname_atom_parser(const struct ref_format *format, struct used_atom *atom,
+				  const char *arg, struct strbuf *err)
+{
+	if (!arg)
+		atom->u.objectname.option = O_FULL;
+	else if (!strcmp(arg, "short"))
+		atom->u.objectname.option = O_SHORT;
+	else if (skip_prefix(arg, "short=", &arg)) {
+		atom->u.objectname.option = O_LENGTH;
+		if (strtoul_ui(arg, 10, &atom->u.objectname.length) ||
+		    atom->u.objectname.length == 0)
+			return strbuf_addf_ret(err, -1, _("positive value expected objectname:short=%s"), arg);
+		if (atom->u.objectname.length < MINIMUM_ABBREV)
+			atom->u.objectname.length = MINIMUM_ABBREV;
+	} else
+		return strbuf_addf_ret(err, -1, _("unrecognized %%(objectname) argument: %s"), arg);
+	return 0;
+}
+
+static int refname_atom_parser(const struct ref_format *format, struct used_atom *atom,
+			       const char *arg, struct strbuf *err)
+{
+	return refname_atom_parser_internal(&atom->u.refname, arg, atom->name, err);
+}
+
+static align_type parse_align_position(const char *s)
+{
+	if (!strcmp(s, "right"))
+		return ALIGN_RIGHT;
+	else if (!strcmp(s, "middle"))
+		return ALIGN_MIDDLE;
+	else if (!strcmp(s, "left"))
+		return ALIGN_LEFT;
+	return -1;
+}
+
+static int align_atom_parser(const struct ref_format *format, struct used_atom *atom,
+			     const char *arg, struct strbuf *err)
+{
+	struct align *align = &atom->u.align;
+	struct string_list params = STRING_LIST_INIT_DUP;
+	int i;
+	unsigned int width = ~0U;
+
+	if (!arg)
+		return strbuf_addf_ret(err, -1, _("expected format: %%(align:<width>,<position>)"));
+
+	align->position = ALIGN_LEFT;
+
+	string_list_split(&params, arg, ',', -1);
+	for (i = 0; i < params.nr; i++) {
+		const char *s = params.items[i].string;
+		int position;
+
+		if (skip_prefix(s, "position=", &s)) {
+			position = parse_align_position(s);
+			if (position < 0) {
+				strbuf_addf(err, _("unrecognized position:%s"), s);
+				string_list_clear(&params, 0);
+				return -1;
+			}
+			align->position = position;
+		} else if (skip_prefix(s, "width=", &s)) {
+			if (strtoul_ui(s, 10, &width)) {
+				strbuf_addf(err, _("unrecognized width:%s"), s);
+				string_list_clear(&params, 0);
+				return -1;
+			}
+		} else if (!strtoul_ui(s, 10, &width))
+			;
+		else if ((position = parse_align_position(s)) >= 0)
+			align->position = position;
+		else {
+			strbuf_addf(err, _("unrecognized %%(align) argument: %s"), s);
+			string_list_clear(&params, 0);
+			return -1;
+		}
+	}
+
+	if (width == ~0U) {
+		string_list_clear(&params, 0);
+		return strbuf_addf_ret(err, -1, _("positive width expected with the %%(align) atom"));
+	}
+	align->width = width;
+	string_list_clear(&params, 0);
+	return 0;
+}
+
+static int if_atom_parser(const struct ref_format *format, struct used_atom *atom,
+			  const char *arg, struct strbuf *err)
+{
+	if (!arg) {
+		atom->u.if_then_else.cmp_status = COMPARE_NONE;
+		return 0;
+	} else if (skip_prefix(arg, "equals=", &atom->u.if_then_else.str)) {
+		atom->u.if_then_else.cmp_status = COMPARE_EQUAL;
+	} else if (skip_prefix(arg, "notequals=", &atom->u.if_then_else.str)) {
+		atom->u.if_then_else.cmp_status = COMPARE_UNEQUAL;
+	} else
+		return strbuf_addf_ret(err, -1, _("unrecognized %%(if) argument: %s"), arg);
+	return 0;
+}
+
+static int head_atom_parser(const struct ref_format *format, struct used_atom *atom,
+			    const char *arg, struct strbuf *unused_err)
+{
+	atom->u.head = resolve_refdup("HEAD", RESOLVE_REF_READING, NULL, NULL);
+	return 0;
+}
+
+static struct {
+	const char *name;
+	info_source source;
+	cmp_type cmp_type;
+	int (*parser)(const struct ref_format *format, struct used_atom *atom,
+		      const char *arg, struct strbuf *err);
+} valid_atom[] = {
+	{ "refname", SOURCE_NONE, FIELD_STR, refname_atom_parser },
+	{ "objecttype", SOURCE_OTHER, FIELD_STR, objecttype_atom_parser },
+	{ "objectsize", SOURCE_OTHER, FIELD_ULONG, objectsize_atom_parser },
+	{ "objectname", SOURCE_OTHER, FIELD_STR, objectname_atom_parser },
+	{ "deltabase", SOURCE_OTHER, FIELD_STR, deltabase_atom_parser },
+	{ "tree", SOURCE_OBJ },
+	{ "parent", SOURCE_OBJ },
+	{ "numparent", SOURCE_OBJ, FIELD_ULONG },
+	{ "object", SOURCE_OBJ },
+	{ "type", SOURCE_OBJ },
+	{ "tag", SOURCE_OBJ },
+	{ "author", SOURCE_OBJ },
+	{ "authorname", SOURCE_OBJ },
+	{ "authoremail", SOURCE_OBJ },
+	{ "authordate", SOURCE_OBJ, FIELD_TIME },
+	{ "committer", SOURCE_OBJ },
+	{ "committername", SOURCE_OBJ },
+	{ "committeremail", SOURCE_OBJ },
+	{ "committerdate", SOURCE_OBJ, FIELD_TIME },
+	{ "tagger", SOURCE_OBJ },
+	{ "taggername", SOURCE_OBJ },
+	{ "taggeremail", SOURCE_OBJ },
+	{ "taggerdate", SOURCE_OBJ, FIELD_TIME },
+	{ "creator", SOURCE_OBJ },
+	{ "creatordate", SOURCE_OBJ, FIELD_TIME },
+	{ "subject", SOURCE_OBJ, FIELD_STR, subject_atom_parser },
+	{ "body", SOURCE_OBJ, FIELD_STR, body_atom_parser },
+	{ "trailers", SOURCE_OBJ, FIELD_STR, trailers_atom_parser },
+	{ "contents", SOURCE_OBJ, FIELD_STR, contents_atom_parser },
+	{ "upstream", SOURCE_NONE, FIELD_STR, remote_ref_atom_parser },
+	{ "push", SOURCE_NONE, FIELD_STR, remote_ref_atom_parser },
+	{ "symref", SOURCE_NONE, FIELD_STR, refname_atom_parser },
+	{ "flag", SOURCE_NONE },
+	{ "HEAD", SOURCE_NONE, FIELD_STR, head_atom_parser },
+	{ "color", SOURCE_NONE, FIELD_STR, color_atom_parser },
+	{ "worktreepath", SOURCE_NONE },
+	{ "align", SOURCE_NONE, FIELD_STR, align_atom_parser },
+	{ "end", SOURCE_NONE },
+	{ "if", SOURCE_NONE, FIELD_STR, if_atom_parser },
+	{ "then", SOURCE_NONE },
+	{ "else", SOURCE_NONE },
+	/*
+	 * Please update $__git_ref_fieldlist in git-completion.bash
+	 * when you add new atoms
+	 */
+};
+
+#define REF_FORMATTING_STATE_INIT  { 0, NULL }
+
+struct ref_formatting_stack {
+	struct ref_formatting_stack *prev;
+	struct strbuf output;
+	void (*at_end)(struct ref_formatting_stack **stack);
+	void *at_end_data;
+};
+
+struct ref_formatting_state {
+	int quote_style;
+	struct ref_formatting_stack *stack;
+};
+
+struct atom_value {
+	const char *s;
+	int (*handler)(struct atom_value *atomv, struct ref_formatting_state *state,
+		       struct strbuf *err);
+	uintmax_t value; /* used for sorting when not FIELD_STR */
+	struct used_atom *atom;
+};
+
+/*
+ * Used to parse format string and sort specifiers
+ */
+static int parse_ref_filter_atom(const struct ref_format *format,
+				 const char *atom, const char *ep,
+				 struct strbuf *err)
+{
+	const char *sp;
+	const char *arg;
+	int i, at, atom_len;
+
+	sp = atom;
+	if (*sp == '*' && sp < ep)
+		sp++; /* deref */
+	if (ep <= sp)
+		return strbuf_addf_ret(err, -1, _("malformed field name: %.*s"),
+				       (int)(ep-atom), atom);
+
+	/* Do we have the atom already used elsewhere? */
+	for (i = 0; i < used_atom_cnt; i++) {
+		int len = strlen(used_atom[i].name);
+		if (len == ep - atom && !memcmp(used_atom[i].name, atom, len))
+			return i;
+	}
+
+	/*
+	 * If the atom name has a colon, strip it and everything after
+	 * it off - it specifies the format for this entry, and
+	 * shouldn't be used for checking against the valid_atom
+	 * table.
+	 */
+	arg = memchr(sp, ':', ep - sp);
+	atom_len = (arg ? arg : ep) - sp;
+
+	/* Is the atom a valid one? */
+	for (i = 0; i < ARRAY_SIZE(valid_atom); i++) {
+		int len = strlen(valid_atom[i].name);
+		if (len == atom_len && !memcmp(valid_atom[i].name, sp, len))
+			break;
+	}
+
+	if (ARRAY_SIZE(valid_atom) <= i)
+		return strbuf_addf_ret(err, -1, _("unknown field name: %.*s"),
+				       (int)(ep-atom), atom);
+	if (valid_atom[i].source != SOURCE_NONE && !have_git_dir())
+		return strbuf_addf_ret(err, -1,
+				       _("not a git repository, but the field '%.*s' requires access to object data"),
+				       (int)(ep-atom), atom);
+
+	/* Add it in, including the deref prefix */
+	at = used_atom_cnt;
+	used_atom_cnt++;
+	REALLOC_ARRAY(used_atom, used_atom_cnt);
+	used_atom[at].name = xmemdupz(atom, ep - atom);
+	used_atom[at].type = valid_atom[i].cmp_type;
+	used_atom[at].source = valid_atom[i].source;
+	if (used_atom[at].source == SOURCE_OBJ) {
+		if (*atom == '*')
+			oi_deref.info.contentp = &oi_deref.content;
+		else
+			oi.info.contentp = &oi.content;
+	}
+	if (arg) {
+		arg = used_atom[at].name + (arg - atom) + 1;
+		if (!*arg) {
+			/*
+			 * Treat empty sub-arguments list as NULL (i.e.,
+			 * "%(atom:)" is equivalent to "%(atom)").
+			 */
+			arg = NULL;
+		}
+	}
+	memset(&used_atom[at].u, 0, sizeof(used_atom[at].u));
+	if (valid_atom[i].parser && valid_atom[i].parser(format, &used_atom[at], arg, err))
+		return -1;
+	if (*atom == '*')
+		need_tagged = 1;
+	if (!strcmp(valid_atom[i].name, "symref"))
+		need_symref = 1;
+	return at;
+}
+
+static void quote_formatting(struct strbuf *s, const char *str, int quote_style)
+{
+	switch (quote_style) {
+	case QUOTE_NONE:
+		strbuf_addstr(s, str);
+		break;
+	case QUOTE_SHELL:
+		sq_quote_buf(s, str);
+		break;
+	case QUOTE_PERL:
+		perl_quote_buf(s, str);
+		break;
+	case QUOTE_PYTHON:
+		python_quote_buf(s, str);
+		break;
+	case QUOTE_TCL:
+		tcl_quote_buf(s, str);
+		break;
+	}
+}
+
+static int append_atom(struct atom_value *v, struct ref_formatting_state *state,
+		       struct strbuf *unused_err)
+{
+	/*
+	 * Quote formatting is only done when the stack has a single
+	 * element. Otherwise quote formatting is done on the
+	 * element's entire output strbuf when the %(end) atom is
+	 * encountered.
+	 */
+	if (!state->stack->prev)
+		quote_formatting(&state->stack->output, v->s, state->quote_style);
+	else
+		strbuf_addstr(&state->stack->output, v->s);
+	return 0;
+}
+
+static void push_stack_element(struct ref_formatting_stack **stack)
+{
+	struct ref_formatting_stack *s = xcalloc(1, sizeof(struct ref_formatting_stack));
+
+	strbuf_init(&s->output, 0);
+	s->prev = *stack;
+	*stack = s;
+}
+
+static void pop_stack_element(struct ref_formatting_stack **stack)
+{
+	struct ref_formatting_stack *current = *stack;
+	struct ref_formatting_stack *prev = current->prev;
+
+	if (prev)
+		strbuf_addbuf(&prev->output, &current->output);
+	strbuf_release(&current->output);
+	free(current);
+	*stack = prev;
+}
+
+static void end_align_handler(struct ref_formatting_stack **stack)
+{
+	struct ref_formatting_stack *cur = *stack;
+	struct align *align = (struct align *)cur->at_end_data;
+	struct strbuf s = STRBUF_INIT;
+
+	strbuf_utf8_align(&s, align->position, align->width, cur->output.buf);
+	strbuf_swap(&cur->output, &s);
+	strbuf_release(&s);
+}
+
+static int align_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state,
+			      struct strbuf *unused_err)
+{
+	struct ref_formatting_stack *new_stack;
+
+	push_stack_element(&state->stack);
+	new_stack = state->stack;
+	new_stack->at_end = end_align_handler;
+	new_stack->at_end_data = &atomv->atom->u.align;
+	return 0;
+}
+
+static void if_then_else_handler(struct ref_formatting_stack **stack)
+{
+	struct ref_formatting_stack *cur = *stack;
+	struct ref_formatting_stack *prev = cur->prev;
+	struct if_then_else *if_then_else = (struct if_then_else *)cur->at_end_data;
+
+	if (!if_then_else->then_atom_seen)
+		die(_("format: %%(if) atom used without a %%(then) atom"));
+
+	if (if_then_else->else_atom_seen) {
+		/*
+		 * There is an %(else) atom: we need to drop one state from the
+		 * stack, either the %(else) branch if the condition is satisfied, or
+		 * the %(then) branch if it isn't.
+		 */
+		if (if_then_else->condition_satisfied) {
+			strbuf_reset(&cur->output);
+			pop_stack_element(&cur);
+		} else {
+			strbuf_swap(&cur->output, &prev->output);
+			strbuf_reset(&cur->output);
+			pop_stack_element(&cur);
+		}
+	} else if (!if_then_else->condition_satisfied) {
+		/*
+		 * No %(else) atom: just drop the %(then) branch if the
+		 * condition is not satisfied.
+		 */
+		strbuf_reset(&cur->output);
+	}
+
+	*stack = cur;
+	free(if_then_else);
+}
+
+static int if_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state,
+			   struct strbuf *unused_err)
+{
+	struct ref_formatting_stack *new_stack;
+	struct if_then_else *if_then_else = xcalloc(sizeof(struct if_then_else), 1);
+
+	if_then_else->str = atomv->atom->u.if_then_else.str;
+	if_then_else->cmp_status = atomv->atom->u.if_then_else.cmp_status;
+
+	push_stack_element(&state->stack);
+	new_stack = state->stack;
+	new_stack->at_end = if_then_else_handler;
+	new_stack->at_end_data = if_then_else;
+	return 0;
+}
+
+static int is_empty(const char *s)
+{
+	while (*s != '\0') {
+		if (!isspace(*s))
+			return 0;
+		s++;
+	}
+	return 1;
+}
+
+static int then_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state,
+			     struct strbuf *err)
+{
+	struct ref_formatting_stack *cur = state->stack;
+	struct if_then_else *if_then_else = NULL;
+
+	if (cur->at_end == if_then_else_handler)
+		if_then_else = (struct if_then_else *)cur->at_end_data;
+	if (!if_then_else)
+		return strbuf_addf_ret(err, -1, _("format: %%(then) atom used without an %%(if) atom"));
+	if (if_then_else->then_atom_seen)
+		return strbuf_addf_ret(err, -1, _("format: %%(then) atom used more than once"));
+	if (if_then_else->else_atom_seen)
+		return strbuf_addf_ret(err, -1, _("format: %%(then) atom used after %%(else)"));
+	if_then_else->then_atom_seen = 1;
+	/*
+	 * If the 'equals' or 'notequals' attribute is used then
+	 * perform the required comparison. If not, only non-empty
+	 * strings satisfy the 'if' condition.
+	 */
+	if (if_then_else->cmp_status == COMPARE_EQUAL) {
+		if (!strcmp(if_then_else->str, cur->output.buf))
+			if_then_else->condition_satisfied = 1;
+	} else if (if_then_else->cmp_status == COMPARE_UNEQUAL) {
+		if (strcmp(if_then_else->str, cur->output.buf))
+			if_then_else->condition_satisfied = 1;
+	} else if (cur->output.len && !is_empty(cur->output.buf))
+		if_then_else->condition_satisfied = 1;
+	strbuf_reset(&cur->output);
+	return 0;
+}
+
+static int else_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state,
+			     struct strbuf *err)
+{
+	struct ref_formatting_stack *prev = state->stack;
+	struct if_then_else *if_then_else = NULL;
+
+	if (prev->at_end == if_then_else_handler)
+		if_then_else = (struct if_then_else *)prev->at_end_data;
+	if (!if_then_else)
+		return strbuf_addf_ret(err, -1, _("format: %%(else) atom used without an %%(if) atom"));
+	if (!if_then_else->then_atom_seen)
+		return strbuf_addf_ret(err, -1, _("format: %%(else) atom used without a %%(then) atom"));
+	if (if_then_else->else_atom_seen)
+		return strbuf_addf_ret(err, -1, _("format: %%(else) atom used more than once"));
+	if_then_else->else_atom_seen = 1;
+	push_stack_element(&state->stack);
+	state->stack->at_end_data = prev->at_end_data;
+	state->stack->at_end = prev->at_end;
+	return 0;
+}
+
+static int end_atom_handler(struct atom_value *atomv, struct ref_formatting_state *state,
+			    struct strbuf *err)
+{
+	struct ref_formatting_stack *current = state->stack;
+	struct strbuf s = STRBUF_INIT;
+
+	if (!current->at_end)
+		return strbuf_addf_ret(err, -1, _("format: %%(end) atom used without corresponding atom"));
+	current->at_end(&state->stack);
+
+	/*  Stack may have been popped within at_end(), hence reset the current pointer */
+	current = state->stack;
+
+	/*
+	 * Perform quote formatting when the stack element is that of
+	 * a supporting atom. If nested then perform quote formatting
+	 * only on the topmost supporting atom.
+	 */
+	if (!current->prev->prev) {
+		quote_formatting(&s, current->output.buf, state->quote_style);
+		strbuf_swap(&current->output, &s);
+	}
+	strbuf_release(&s);
+	pop_stack_element(&state->stack);
+	return 0;
+}
+
+/*
+ * In a format string, find the next occurrence of %(atom).
+ */
+static const char *find_next(const char *cp)
+{
+	while (*cp) {
+		if (*cp == '%') {
+			/*
+			 * %( is the start of an atom;
+			 * %% is a quoted per-cent.
+			 */
+			if (cp[1] == '(')
+				return cp;
+			else if (cp[1] == '%')
+				cp++; /* skip over two % */
+			/* otherwise this is a singleton, literal % */
+		}
+		cp++;
+	}
+	return NULL;
+}
+
+/*
+ * Make sure the format string is well formed, and parse out
+ * the used atoms.
+ */
+int verify_ref_format(struct ref_format *format)
+{
+	const char *cp, *sp;
+
+	format->need_color_reset_at_eol = 0;
+	for (cp = format->format; *cp && (sp = find_next(cp)); ) {
+		struct strbuf err = STRBUF_INIT;
+		const char *color, *ep = strchr(sp, ')');
+		int at;
+
+		if (!ep)
+			return error(_("malformed format string %s"), sp);
+		/* sp points at "%(" and ep points at the closing ")" */
+		at = parse_ref_filter_atom(format, sp + 2, ep, &err);
+		if (at < 0)
+			die("%s", err.buf);
+		cp = ep + 1;
+
+		if (skip_prefix(used_atom[at].name, "color:", &color))
+			format->need_color_reset_at_eol = !!strcmp(color, "reset");
+		strbuf_release(&err);
+	}
+	if (format->need_color_reset_at_eol && !want_color(format->use_color))
+		format->need_color_reset_at_eol = 0;
+	return 0;
+}
+
+static int grab_objectname(const char *name, const struct object_id *oid,
+			   struct atom_value *v, struct used_atom *atom)
+{
+	if (starts_with(name, "objectname")) {
+		if (atom->u.objectname.option == O_SHORT) {
+			v->s = xstrdup(find_unique_abbrev(oid, DEFAULT_ABBREV));
+			return 1;
+		} else if (atom->u.objectname.option == O_FULL) {
+			v->s = xstrdup(oid_to_hex(oid));
+			return 1;
+		} else if (atom->u.objectname.option == O_LENGTH) {
+			v->s = xstrdup(find_unique_abbrev(oid, atom->u.objectname.length));
+			return 1;
+		} else
+			BUG("unknown %%(objectname) option");
+	}
+	return 0;
+}
+
+/* See grab_values */
+static void grab_common_values(struct atom_value *val, int deref, struct expand_data *oi)
+{
+	int i;
+
+	for (i = 0; i < used_atom_cnt; i++) {
+		const char *name = used_atom[i].name;
+		struct atom_value *v = &val[i];
+		if (!!deref != (*name == '*'))
+			continue;
+		if (deref)
+			name++;
+		if (!strcmp(name, "objecttype"))
+			v->s = xstrdup(type_name(oi->type));
+		else if (!strcmp(name, "objectsize:disk")) {
+			v->value = oi->disk_size;
+			v->s = xstrfmt("%"PRIuMAX, (uintmax_t)oi->disk_size);
+		} else if (!strcmp(name, "objectsize")) {
+			v->value = oi->size;
+			v->s = xstrfmt("%"PRIuMAX , (uintmax_t)oi->size);
+		} else if (!strcmp(name, "deltabase"))
+			v->s = xstrdup(oid_to_hex(&oi->delta_base_oid));
+		else if (deref)
+			grab_objectname(name, &oi->oid, v, &used_atom[i]);
+	}
+}
+
+/* See grab_values */
+static void grab_tag_values(struct atom_value *val, int deref, struct object *obj)
+{
+	int i;
+	struct tag *tag = (struct tag *) obj;
+
+	for (i = 0; i < used_atom_cnt; i++) {
+		const char *name = used_atom[i].name;
+		struct atom_value *v = &val[i];
+		if (!!deref != (*name == '*'))
+			continue;
+		if (deref)
+			name++;
+		if (!strcmp(name, "tag"))
+			v->s = xstrdup(tag->tag);
+		else if (!strcmp(name, "type") && tag->tagged)
+			v->s = xstrdup(type_name(tag->tagged->type));
+		else if (!strcmp(name, "object") && tag->tagged)
+			v->s = xstrdup(oid_to_hex(&tag->tagged->oid));
+	}
+}
+
+/* See grab_values */
+static void grab_commit_values(struct atom_value *val, int deref, struct object *obj)
+{
+	int i;
+	struct commit *commit = (struct commit *) obj;
+
+	for (i = 0; i < used_atom_cnt; i++) {
+		const char *name = used_atom[i].name;
+		struct atom_value *v = &val[i];
+		if (!!deref != (*name == '*'))
+			continue;
+		if (deref)
+			name++;
+		if (!strcmp(name, "tree")) {
+			v->s = xstrdup(oid_to_hex(get_commit_tree_oid(commit)));
+		}
+		else if (!strcmp(name, "numparent")) {
+			v->value = commit_list_count(commit->parents);
+			v->s = xstrfmt("%lu", (unsigned long)v->value);
+		}
+		else if (!strcmp(name, "parent")) {
+			struct commit_list *parents;
+			struct strbuf s = STRBUF_INIT;
+			for (parents = commit->parents; parents; parents = parents->next) {
+				struct commit *parent = parents->item;
+				if (parents != commit->parents)
+					strbuf_addch(&s, ' ');
+				strbuf_addstr(&s, oid_to_hex(&parent->object.oid));
+			}
+			v->s = strbuf_detach(&s, NULL);
+		}
+	}
+}
+
+static const char *find_wholine(const char *who, int wholen, const char *buf)
+{
+	const char *eol;
+	while (*buf) {
+		if (!strncmp(buf, who, wholen) &&
+		    buf[wholen] == ' ')
+			return buf + wholen + 1;
+		eol = strchr(buf, '\n');
+		if (!eol)
+			return "";
+		eol++;
+		if (*eol == '\n')
+			return ""; /* end of header */
+		buf = eol;
+	}
+	return "";
+}
+
+static const char *copy_line(const char *buf)
+{
+	const char *eol = strchrnul(buf, '\n');
+	return xmemdupz(buf, eol - buf);
+}
+
+static const char *copy_name(const char *buf)
+{
+	const char *cp;
+	for (cp = buf; *cp && *cp != '\n'; cp++) {
+		if (!strncmp(cp, " <", 2))
+			return xmemdupz(buf, cp - buf);
+	}
+	return "";
+}
+
+static const char *copy_email(const char *buf)
+{
+	const char *email = strchr(buf, '<');
+	const char *eoemail;
+	if (!email)
+		return "";
+	eoemail = strchr(email, '>');
+	if (!eoemail)
+		return "";
+	return xmemdupz(email, eoemail + 1 - email);
+}
+
+static char *copy_subject(const char *buf, unsigned long len)
+{
+	char *r = xmemdupz(buf, len);
+	int i;
+
+	for (i = 0; i < len; i++)
+		if (r[i] == '\n')
+			r[i] = ' ';
+
+	return r;
+}
+
+static void grab_date(const char *buf, struct atom_value *v, const char *atomname)
+{
+	const char *eoemail = strstr(buf, "> ");
+	char *zone;
+	timestamp_t timestamp;
+	long tz;
+	struct date_mode date_mode = { DATE_NORMAL };
+	const char *formatp;
+
+	/*
+	 * We got here because atomname ends in "date" or "date<something>";
+	 * it's not possible that <something> is not ":<format>" because
+	 * parse_ref_filter_atom() wouldn't have allowed it, so we can assume that no
+	 * ":" means no format is specified, and use the default.
+	 */
+	formatp = strchr(atomname, ':');
+	if (formatp != NULL) {
+		formatp++;
+		parse_date_format(formatp, &date_mode);
+	}
+
+	if (!eoemail)
+		goto bad;
+	timestamp = parse_timestamp(eoemail + 2, &zone, 10);
+	if (timestamp == TIME_MAX)
+		goto bad;
+	tz = strtol(zone, NULL, 10);
+	if ((tz == LONG_MIN || tz == LONG_MAX) && errno == ERANGE)
+		goto bad;
+	v->s = xstrdup(show_date(timestamp, tz, &date_mode));
+	v->value = timestamp;
+	return;
+ bad:
+	v->s = xstrdup("");
+	v->value = 0;
+}
+
+/* See grab_values */
+static void grab_person(const char *who, struct atom_value *val, int deref, void *buf)
+{
+	int i;
+	int wholen = strlen(who);
+	const char *wholine = NULL;
+
+	for (i = 0; i < used_atom_cnt; i++) {
+		const char *name = used_atom[i].name;
+		struct atom_value *v = &val[i];
+		if (!!deref != (*name == '*'))
+			continue;
+		if (deref)
+			name++;
+		if (strncmp(who, name, wholen))
+			continue;
+		if (name[wholen] != 0 &&
+		    strcmp(name + wholen, "name") &&
+		    strcmp(name + wholen, "email") &&
+		    !starts_with(name + wholen, "date"))
+			continue;
+		if (!wholine)
+			wholine = find_wholine(who, wholen, buf);
+		if (!wholine)
+			return; /* no point looking for it */
+		if (name[wholen] == 0)
+			v->s = copy_line(wholine);
+		else if (!strcmp(name + wholen, "name"))
+			v->s = copy_name(wholine);
+		else if (!strcmp(name + wholen, "email"))
+			v->s = copy_email(wholine);
+		else if (starts_with(name + wholen, "date"))
+			grab_date(wholine, v, name);
+	}
+
+	/*
+	 * For a tag or a commit object, if "creator" or "creatordate" is
+	 * requested, do something special.
+	 */
+	if (strcmp(who, "tagger") && strcmp(who, "committer"))
+		return; /* "author" for commit object is not wanted */
+	if (!wholine)
+		wholine = find_wholine(who, wholen, buf);
+	if (!wholine)
+		return;
+	for (i = 0; i < used_atom_cnt; i++) {
+		const char *name = used_atom[i].name;
+		struct atom_value *v = &val[i];
+		if (!!deref != (*name == '*'))
+			continue;
+		if (deref)
+			name++;
+
+		if (starts_with(name, "creatordate"))
+			grab_date(wholine, v, name);
+		else if (!strcmp(name, "creator"))
+			v->s = copy_line(wholine);
+	}
+}
+
+static void find_subpos(const char *buf,
+			const char **sub, unsigned long *sublen,
+			const char **body, unsigned long *bodylen,
+			unsigned long *nonsiglen,
+			const char **sig, unsigned long *siglen)
+{
+	const char *eol;
+	/* skip past header until we hit empty line */
+	while (*buf && *buf != '\n') {
+		eol = strchrnul(buf, '\n');
+		if (*eol)
+			eol++;
+		buf = eol;
+	}
+	/* skip any empty lines */
+	while (*buf == '\n')
+		buf++;
+
+	/* parse signature first; we might not even have a subject line */
+	*sig = buf + parse_signature(buf, strlen(buf));
+	*siglen = strlen(*sig);
+
+	/* subject is first non-empty line */
+	*sub = buf;
+	/* subject goes to first empty line */
+	while (buf < *sig && *buf && *buf != '\n') {
+		eol = strchrnul(buf, '\n');
+		if (*eol)
+			eol++;
+		buf = eol;
+	}
+	*sublen = buf - *sub;
+	/* drop trailing newline, if present */
+	if (*sublen && (*sub)[*sublen - 1] == '\n')
+		*sublen -= 1;
+
+	/* skip any empty lines */
+	while (*buf == '\n')
+		buf++;
+	*body = buf;
+	*bodylen = strlen(buf);
+	*nonsiglen = *sig - buf;
+}
+
+/*
+ * If 'lines' is greater than 0, append that many lines from the given
+ * 'buf' of length 'size' to the given strbuf.
+ */
+static void append_lines(struct strbuf *out, const char *buf, unsigned long size, int lines)
+{
+	int i;
+	const char *sp, *eol;
+	size_t len;
+
+	sp = buf;
+
+	for (i = 0; i < lines && sp < buf + size; i++) {
+		if (i)
+			strbuf_addstr(out, "\n    ");
+		eol = memchr(sp, '\n', size - (sp - buf));
+		len = eol ? eol - sp : size - (sp - buf);
+		strbuf_add(out, sp, len);
+		if (!eol)
+			break;
+		sp = eol + 1;
+	}
+}
+
+/* See grab_values */
+static void grab_sub_body_contents(struct atom_value *val, int deref, void *buf)
+{
+	int i;
+	const char *subpos = NULL, *bodypos = NULL, *sigpos = NULL;
+	unsigned long sublen = 0, bodylen = 0, nonsiglen = 0, siglen = 0;
+
+	for (i = 0; i < used_atom_cnt; i++) {
+		struct used_atom *atom = &used_atom[i];
+		const char *name = atom->name;
+		struct atom_value *v = &val[i];
+		if (!!deref != (*name == '*'))
+			continue;
+		if (deref)
+			name++;
+		if (strcmp(name, "subject") &&
+		    strcmp(name, "body") &&
+		    !starts_with(name, "trailers") &&
+		    !starts_with(name, "contents"))
+			continue;
+		if (!subpos)
+			find_subpos(buf,
+				    &subpos, &sublen,
+				    &bodypos, &bodylen, &nonsiglen,
+				    &sigpos, &siglen);
+
+		if (atom->u.contents.option == C_SUB)
+			v->s = copy_subject(subpos, sublen);
+		else if (atom->u.contents.option == C_BODY_DEP)
+			v->s = xmemdupz(bodypos, bodylen);
+		else if (atom->u.contents.option == C_BODY)
+			v->s = xmemdupz(bodypos, nonsiglen);
+		else if (atom->u.contents.option == C_SIG)
+			v->s = xmemdupz(sigpos, siglen);
+		else if (atom->u.contents.option == C_LINES) {
+			struct strbuf s = STRBUF_INIT;
+			const char *contents_end = bodylen + bodypos - siglen;
+
+			/*  Size is the length of the message after removing the signature */
+			append_lines(&s, subpos, contents_end - subpos, atom->u.contents.nlines);
+			v->s = strbuf_detach(&s, NULL);
+		} else if (atom->u.contents.option == C_TRAILERS) {
+			struct strbuf s = STRBUF_INIT;
+
+			/* Format the trailer info according to the trailer_opts given */
+			format_trailers_from_commit(&s, subpos, &atom->u.contents.trailer_opts);
+
+			v->s = strbuf_detach(&s, NULL);
+		} else if (atom->u.contents.option == C_BARE)
+			v->s = xstrdup(subpos);
+	}
+}
+
+/*
+ * We want to have empty print-string for field requests
+ * that do not apply (e.g. "authordate" for a tag object)
+ */
+static void fill_missing_values(struct atom_value *val)
+{
+	int i;
+	for (i = 0; i < used_atom_cnt; i++) {
+		struct atom_value *v = &val[i];
+		if (v->s == NULL)
+			v->s = xstrdup("");
+	}
+}
+
+/*
+ * val is a list of atom_value to hold returned values.  Extract
+ * the values for atoms in used_atom array out of (obj, buf, sz).
+ * when deref is false, (obj, buf, sz) is the object that is
+ * pointed at by the ref itself; otherwise it is the object the
+ * ref (which is a tag) refers to.
+ */
+static void grab_values(struct atom_value *val, int deref, struct object *obj, void *buf)
+{
+	switch (obj->type) {
+	case OBJ_TAG:
+		grab_tag_values(val, deref, obj);
+		grab_sub_body_contents(val, deref, buf);
+		grab_person("tagger", val, deref, buf);
+		break;
+	case OBJ_COMMIT:
+		grab_commit_values(val, deref, obj);
+		grab_sub_body_contents(val, deref, buf);
+		grab_person("author", val, deref, buf);
+		grab_person("committer", val, deref, buf);
+		break;
+	case OBJ_TREE:
+		/* grab_tree_values(val, deref, obj, buf, sz); */
+		break;
+	case OBJ_BLOB:
+		/* grab_blob_values(val, deref, obj, buf, sz); */
+		break;
+	default:
+		die("Eh?  Object of type %d?", obj->type);
+	}
+}
+
+static inline char *copy_advance(char *dst, const char *src)
+{
+	while (*src)
+		*dst++ = *src++;
+	return dst;
+}
+
+static const char *lstrip_ref_components(const char *refname, int len)
+{
+	long remaining = len;
+	const char *start = xstrdup(refname);
+	const char *to_free = start;
+
+	if (len < 0) {
+		int i;
+		const char *p = refname;
+
+		/* Find total no of '/' separated path-components */
+		for (i = 0; p[i]; p[i] == '/' ? i++ : *p++)
+			;
+		/*
+		 * The number of components we need to strip is now
+		 * the total minus the components to be left (Plus one
+		 * because we count the number of '/', but the number
+		 * of components is one more than the no of '/').
+		 */
+		remaining = i + len + 1;
+	}
+
+	while (remaining > 0) {
+		switch (*start++) {
+		case '\0':
+			free((char *)to_free);
+			return xstrdup("");
+		case '/':
+			remaining--;
+			break;
+		}
+	}
+
+	start = xstrdup(start);
+	free((char *)to_free);
+	return start;
+}
+
+static const char *rstrip_ref_components(const char *refname, int len)
+{
+	long remaining = len;
+	const char *start = xstrdup(refname);
+	const char *to_free = start;
+
+	if (len < 0) {
+		int i;
+		const char *p = refname;
+
+		/* Find total no of '/' separated path-components */
+		for (i = 0; p[i]; p[i] == '/' ? i++ : *p++)
+			;
+		/*
+		 * The number of components we need to strip is now
+		 * the total minus the components to be left (Plus one
+		 * because we count the number of '/', but the number
+		 * of components is one more than the no of '/').
+		 */
+		remaining = i + len + 1;
+	}
+
+	while (remaining-- > 0) {
+		char *p = strrchr(start, '/');
+		if (p == NULL) {
+			free((char *)to_free);
+			return xstrdup("");
+		} else
+			p[0] = '\0';
+	}
+	return start;
+}
+
+static const char *show_ref(struct refname_atom *atom, const char *refname)
+{
+	if (atom->option == R_SHORT)
+		return shorten_unambiguous_ref(refname, warn_ambiguous_refs);
+	else if (atom->option == R_LSTRIP)
+		return lstrip_ref_components(refname, atom->lstrip);
+	else if (atom->option == R_RSTRIP)
+		return rstrip_ref_components(refname, atom->rstrip);
+	else
+		return xstrdup(refname);
+}
+
+static void fill_remote_ref_details(struct used_atom *atom, const char *refname,
+				    struct branch *branch, const char **s)
+{
+	int num_ours, num_theirs;
+	if (atom->u.remote_ref.option == RR_REF)
+		*s = show_ref(&atom->u.remote_ref.refname, refname);
+	else if (atom->u.remote_ref.option == RR_TRACK) {
+		if (stat_tracking_info(branch, &num_ours, &num_theirs,
+				       NULL, atom->u.remote_ref.push,
+				       AHEAD_BEHIND_FULL) < 0) {
+			*s = xstrdup(msgs.gone);
+		} else if (!num_ours && !num_theirs)
+			*s = xstrdup("");
+		else if (!num_ours)
+			*s = xstrfmt(msgs.behind, num_theirs);
+		else if (!num_theirs)
+			*s = xstrfmt(msgs.ahead, num_ours);
+		else
+			*s = xstrfmt(msgs.ahead_behind,
+				     num_ours, num_theirs);
+		if (!atom->u.remote_ref.nobracket && *s[0]) {
+			const char *to_free = *s;
+			*s = xstrfmt("[%s]", *s);
+			free((void *)to_free);
+		}
+	} else if (atom->u.remote_ref.option == RR_TRACKSHORT) {
+		if (stat_tracking_info(branch, &num_ours, &num_theirs,
+				       NULL, atom->u.remote_ref.push,
+				       AHEAD_BEHIND_FULL) < 0) {
+			*s = xstrdup("");
+			return;
+		}
+		if (!num_ours && !num_theirs)
+			*s = xstrdup("=");
+		else if (!num_ours)
+			*s = xstrdup("<");
+		else if (!num_theirs)
+			*s = xstrdup(">");
+		else
+			*s = xstrdup("<>");
+	} else if (atom->u.remote_ref.option == RR_REMOTE_NAME) {
+		int explicit;
+		const char *remote = atom->u.remote_ref.push ?
+			pushremote_for_branch(branch, &explicit) :
+			remote_for_branch(branch, &explicit);
+		*s = xstrdup(explicit ? remote : "");
+	} else if (atom->u.remote_ref.option == RR_REMOTE_REF) {
+		int explicit;
+		const char *merge;
+
+		merge = remote_ref_for_branch(branch, atom->u.remote_ref.push,
+					      &explicit);
+		*s = xstrdup(explicit ? merge : "");
+	} else
+		BUG("unhandled RR_* enum");
+}
+
+char *get_head_description(void)
+{
+	struct strbuf desc = STRBUF_INIT;
+	struct wt_status_state state;
+	memset(&state, 0, sizeof(state));
+	wt_status_get_state(the_repository, &state, 1);
+
+	/*
+	 * The ( character must be hard-coded and not part of a localizable
+	 * string, since the description is used as a sort key and compared
+	 * with ref names.
+	 */
+	strbuf_addch(&desc, '(');
+	if (state.rebase_in_progress ||
+	    state.rebase_interactive_in_progress) {
+		if (state.branch)
+			strbuf_addf(&desc, _("no branch, rebasing %s"),
+				    state.branch);
+		else
+			strbuf_addf(&desc, _("no branch, rebasing detached HEAD %s"),
+				    state.detached_from);
+	} else if (state.bisect_in_progress)
+		strbuf_addf(&desc, _("no branch, bisect started on %s"),
+			    state.branch);
+	else if (state.detached_from) {
+		if (state.detached_at)
+			strbuf_addstr(&desc, HEAD_DETACHED_AT);
+		else
+			strbuf_addstr(&desc, HEAD_DETACHED_FROM);
+		strbuf_addstr(&desc, state.detached_from);
+	}
+	else
+		strbuf_addstr(&desc, _("no branch"));
+	strbuf_addch(&desc, ')');
+
+	free(state.branch);
+	free(state.onto);
+	free(state.detached_from);
+	return strbuf_detach(&desc, NULL);
+}
+
+static const char *get_symref(struct used_atom *atom, struct ref_array_item *ref)
+{
+	if (!ref->symref)
+		return xstrdup("");
+	else
+		return show_ref(&atom->u.refname, ref->symref);
+}
+
+static const char *get_refname(struct used_atom *atom, struct ref_array_item *ref)
+{
+	if (ref->kind & FILTER_REFS_DETACHED_HEAD)
+		return get_head_description();
+	return show_ref(&atom->u.refname, ref->refname);
+}
+
+static int get_object(struct ref_array_item *ref, int deref, struct object **obj,
+		      struct expand_data *oi, struct strbuf *err)
+{
+	/* parse_object_buffer() will set eaten to 0 if free() will be needed */
+	int eaten = 1;
+	if (oi->info.contentp) {
+		/* We need to know that to use parse_object_buffer properly */
+		oi->info.sizep = &oi->size;
+		oi->info.typep = &oi->type;
+	}
+	if (oid_object_info_extended(the_repository, &oi->oid, &oi->info,
+				     OBJECT_INFO_LOOKUP_REPLACE))
+		return strbuf_addf_ret(err, -1, _("missing object %s for %s"),
+				       oid_to_hex(&oi->oid), ref->refname);
+	if (oi->info.disk_sizep && oi->disk_size < 0)
+		BUG("Object size is less than zero.");
+
+	if (oi->info.contentp) {
+		*obj = parse_object_buffer(the_repository, &oi->oid, oi->type, oi->size, oi->content, &eaten);
+		if (!obj) {
+			if (!eaten)
+				free(oi->content);
+			return strbuf_addf_ret(err, -1, _("parse_object_buffer failed on %s for %s"),
+					       oid_to_hex(&oi->oid), ref->refname);
+		}
+		grab_values(ref->value, deref, *obj, oi->content);
+	}
+
+	grab_common_values(ref->value, deref, oi);
+	if (!eaten)
+		free(oi->content);
+	return 0;
+}
+
+static void populate_worktree_map(struct hashmap *map, struct worktree **worktrees)
+{
+	int i;
+
+	for (i = 0; worktrees[i]; i++) {
+		if (worktrees[i]->head_ref) {
+			struct ref_to_worktree_entry *entry;
+			entry = xmalloc(sizeof(*entry));
+			entry->wt = worktrees[i];
+			hashmap_entry_init(entry, strhash(worktrees[i]->head_ref));
+
+			hashmap_add(map, entry);
+		}
+	}
+}
+
+static void lazy_init_worktree_map(void)
+{
+	if (ref_to_worktree_map.worktrees)
+		return;
+
+	ref_to_worktree_map.worktrees = get_worktrees(0);
+	hashmap_init(&(ref_to_worktree_map.map), ref_to_worktree_map_cmpfnc, NULL, 0);
+	populate_worktree_map(&(ref_to_worktree_map.map), ref_to_worktree_map.worktrees);
+}
+
+static char *get_worktree_path(const struct used_atom *atom, const struct ref_array_item *ref)
+{
+	struct hashmap_entry entry;
+	struct ref_to_worktree_entry *lookup_result;
+
+	lazy_init_worktree_map();
+
+	hashmap_entry_init(&entry, strhash(ref->refname));
+	lookup_result = hashmap_get(&(ref_to_worktree_map.map), &entry, ref->refname);
+
+	if (lookup_result)
+		return xstrdup(lookup_result->wt->path);
+	else
+		return xstrdup("");
+}
+
+/*
+ * Parse the object referred by ref, and grab needed value.
+ */
+static int populate_value(struct ref_array_item *ref, struct strbuf *err)
+{
+	struct object *obj;
+	int i;
+	struct object_info empty = OBJECT_INFO_INIT;
+
+	ref->value = xcalloc(used_atom_cnt, sizeof(struct atom_value));
+
+	if (need_symref && (ref->flag & REF_ISSYMREF) && !ref->symref) {
+		ref->symref = resolve_refdup(ref->refname, RESOLVE_REF_READING,
+					     NULL, NULL);
+		if (!ref->symref)
+			ref->symref = xstrdup("");
+	}
+
+	/* Fill in specials first */
+	for (i = 0; i < used_atom_cnt; i++) {
+		struct used_atom *atom = &used_atom[i];
+		const char *name = used_atom[i].name;
+		struct atom_value *v = &ref->value[i];
+		int deref = 0;
+		const char *refname;
+		struct branch *branch = NULL;
+
+		v->handler = append_atom;
+		v->atom = atom;
+
+		if (*name == '*') {
+			deref = 1;
+			name++;
+		}
+
+		if (starts_with(name, "refname"))
+			refname = get_refname(atom, ref);
+		else if (!strcmp(name, "worktreepath")) {
+			if (ref->kind == FILTER_REFS_BRANCHES)
+				v->s = get_worktree_path(atom, ref);
+			else
+				v->s = xstrdup("");
+			continue;
+		}
+		else if (starts_with(name, "symref"))
+			refname = get_symref(atom, ref);
+		else if (starts_with(name, "upstream")) {
+			const char *branch_name;
+			/* only local branches may have an upstream */
+			if (!skip_prefix(ref->refname, "refs/heads/",
+					 &branch_name)) {
+				v->s = xstrdup("");
+				continue;
+			}
+			branch = branch_get(branch_name);
+
+			refname = branch_get_upstream(branch, NULL);
+			if (refname)
+				fill_remote_ref_details(atom, refname, branch, &v->s);
+			else
+				v->s = xstrdup("");
+			continue;
+		} else if (atom->u.remote_ref.push) {
+			const char *branch_name;
+			v->s = xstrdup("");
+			if (!skip_prefix(ref->refname, "refs/heads/",
+					 &branch_name))
+				continue;
+			branch = branch_get(branch_name);
+
+			if (atom->u.remote_ref.push_remote)
+				refname = NULL;
+			else {
+				refname = branch_get_push(branch, NULL);
+				if (!refname)
+					continue;
+			}
+			/* We will definitely re-init v->s on the next line. */
+			free((char *)v->s);
+			fill_remote_ref_details(atom, refname, branch, &v->s);
+			continue;
+		} else if (starts_with(name, "color:")) {
+			v->s = xstrdup(atom->u.color);
+			continue;
+		} else if (!strcmp(name, "flag")) {
+			char buf[256], *cp = buf;
+			if (ref->flag & REF_ISSYMREF)
+				cp = copy_advance(cp, ",symref");
+			if (ref->flag & REF_ISPACKED)
+				cp = copy_advance(cp, ",packed");
+			if (cp == buf)
+				v->s = xstrdup("");
+			else {
+				*cp = '\0';
+				v->s = xstrdup(buf + 1);
+			}
+			continue;
+		} else if (!deref && grab_objectname(name, &ref->objectname, v, atom)) {
+			continue;
+		} else if (!strcmp(name, "HEAD")) {
+			if (atom->u.head && !strcmp(ref->refname, atom->u.head))
+				v->s = xstrdup("*");
+			else
+				v->s = xstrdup(" ");
+			continue;
+		} else if (starts_with(name, "align")) {
+			v->handler = align_atom_handler;
+			v->s = xstrdup("");
+			continue;
+		} else if (!strcmp(name, "end")) {
+			v->handler = end_atom_handler;
+			v->s = xstrdup("");
+			continue;
+		} else if (starts_with(name, "if")) {
+			const char *s;
+			if (skip_prefix(name, "if:", &s))
+				v->s = xstrdup(s);
+			else
+				v->s = xstrdup("");
+			v->handler = if_atom_handler;
+			continue;
+		} else if (!strcmp(name, "then")) {
+			v->handler = then_atom_handler;
+			v->s = xstrdup("");
+			continue;
+		} else if (!strcmp(name, "else")) {
+			v->handler = else_atom_handler;
+			v->s = xstrdup("");
+			continue;
+		} else
+			continue;
+
+		if (!deref)
+			v->s = xstrdup(refname);
+		else
+			v->s = xstrfmt("%s^{}", refname);
+		free((char *)refname);
+	}
+
+	for (i = 0; i < used_atom_cnt; i++) {
+		struct atom_value *v = &ref->value[i];
+		if (v->s == NULL && used_atom[i].source == SOURCE_NONE)
+			return strbuf_addf_ret(err, -1, _("missing object %s for %s"),
+					       oid_to_hex(&ref->objectname), ref->refname);
+	}
+
+	if (need_tagged)
+		oi.info.contentp = &oi.content;
+	if (!memcmp(&oi.info, &empty, sizeof(empty)) &&
+	    !memcmp(&oi_deref.info, &empty, sizeof(empty)))
+		return 0;
+
+
+	oi.oid = ref->objectname;
+	if (get_object(ref, 0, &obj, &oi, err))
+		return -1;
+
+	/*
+	 * If there is no atom that wants to know about tagged
+	 * object, we are done.
+	 */
+	if (!need_tagged || (obj->type != OBJ_TAG))
+		return 0;
+
+	/*
+	 * If it is a tag object, see if we use a value that derefs
+	 * the object, and if we do grab the object it refers to.
+	 */
+	oi_deref.oid = ((struct tag *)obj)->tagged->oid;
+
+	/*
+	 * NEEDSWORK: This derefs tag only once, which
+	 * is good to deal with chains of trust, but
+	 * is not consistent with what deref_tag() does
+	 * which peels the onion to the core.
+	 */
+	return get_object(ref, 1, &obj, &oi_deref, err);
+}
+
+/*
+ * Given a ref, return the value for the atom.  This lazily gets value
+ * out of the object by calling populate value.
+ */
+static int get_ref_atom_value(struct ref_array_item *ref, int atom,
+			      struct atom_value **v, struct strbuf *err)
+{
+	if (!ref->value) {
+		if (populate_value(ref, err))
+			return -1;
+		fill_missing_values(ref->value);
+	}
+	*v = &ref->value[atom];
+	return 0;
+}
+
+/*
+ * Return 1 if the refname matches one of the patterns, otherwise 0.
+ * A pattern can be a literal prefix (e.g. a refname "refs/heads/master"
+ * matches a pattern "refs/heads/mas") or a wildcard (e.g. the same ref
+ * matches "refs/heads/mas*", too).
+ */
+static int match_pattern(const struct ref_filter *filter, const char *refname)
+{
+	const char **patterns = filter->name_patterns;
+	unsigned flags = 0;
+
+	if (filter->ignore_case)
+		flags |= WM_CASEFOLD;
+
+	/*
+	 * When no '--format' option is given we need to skip the prefix
+	 * for matching refs of tags and branches.
+	 */
+	(void)(skip_prefix(refname, "refs/tags/", &refname) ||
+	       skip_prefix(refname, "refs/heads/", &refname) ||
+	       skip_prefix(refname, "refs/remotes/", &refname) ||
+	       skip_prefix(refname, "refs/", &refname));
+
+	for (; *patterns; patterns++) {
+		if (!wildmatch(*patterns, refname, flags))
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * Return 1 if the refname matches one of the patterns, otherwise 0.
+ * A pattern can be path prefix (e.g. a refname "refs/heads/master"
+ * matches a pattern "refs/heads/" but not "refs/heads/m") or a
+ * wildcard (e.g. the same ref matches "refs/heads/m*", too).
+ */
+static int match_name_as_path(const struct ref_filter *filter, const char *refname)
+{
+	const char **pattern = filter->name_patterns;
+	int namelen = strlen(refname);
+	unsigned flags = WM_PATHNAME;
+
+	if (filter->ignore_case)
+		flags |= WM_CASEFOLD;
+
+	for (; *pattern; pattern++) {
+		const char *p = *pattern;
+		int plen = strlen(p);
+
+		if ((plen <= namelen) &&
+		    !strncmp(refname, p, plen) &&
+		    (refname[plen] == '\0' ||
+		     refname[plen] == '/' ||
+		     p[plen-1] == '/'))
+			return 1;
+		if (!wildmatch(p, refname, flags))
+			return 1;
+	}
+	return 0;
+}
+
+/* Return 1 if the refname matches one of the patterns, otherwise 0. */
+static int filter_pattern_match(struct ref_filter *filter, const char *refname)
+{
+	if (!*filter->name_patterns)
+		return 1; /* No pattern always matches */
+	if (filter->match_as_path)
+		return match_name_as_path(filter, refname);
+	return match_pattern(filter, refname);
+}
+
+static int qsort_strcmp(const void *va, const void *vb)
+{
+	const char *a = *(const char **)va;
+	const char *b = *(const char **)vb;
+
+	return strcmp(a, b);
+}
+
+static void find_longest_prefixes_1(struct string_list *out,
+				  struct strbuf *prefix,
+				  const char **patterns, size_t nr)
+{
+	size_t i;
+
+	for (i = 0; i < nr; i++) {
+		char c = patterns[i][prefix->len];
+		if (!c || is_glob_special(c)) {
+			string_list_append(out, prefix->buf);
+			return;
+		}
+	}
+
+	i = 0;
+	while (i < nr) {
+		size_t end;
+
+		/*
+		* Set "end" to the index of the element _after_ the last one
+		* in our group.
+		*/
+		for (end = i + 1; end < nr; end++) {
+			if (patterns[i][prefix->len] != patterns[end][prefix->len])
+				break;
+		}
+
+		strbuf_addch(prefix, patterns[i][prefix->len]);
+		find_longest_prefixes_1(out, prefix, patterns + i, end - i);
+		strbuf_setlen(prefix, prefix->len - 1);
+
+		i = end;
+	}
+}
+
+static void find_longest_prefixes(struct string_list *out,
+				  const char **patterns)
+{
+	struct argv_array sorted = ARGV_ARRAY_INIT;
+	struct strbuf prefix = STRBUF_INIT;
+
+	argv_array_pushv(&sorted, patterns);
+	QSORT(sorted.argv, sorted.argc, qsort_strcmp);
+
+	find_longest_prefixes_1(out, &prefix, sorted.argv, sorted.argc);
+
+	argv_array_clear(&sorted);
+	strbuf_release(&prefix);
+}
+
+/*
+ * This is the same as for_each_fullref_in(), but it tries to iterate
+ * only over the patterns we'll care about. Note that it _doesn't_ do a full
+ * pattern match, so the callback still has to match each ref individually.
+ */
+static int for_each_fullref_in_pattern(struct ref_filter *filter,
+				       each_ref_fn cb,
+				       void *cb_data,
+				       int broken)
+{
+	struct string_list prefixes = STRING_LIST_INIT_DUP;
+	struct string_list_item *prefix;
+	int ret;
+
+	if (!filter->match_as_path) {
+		/*
+		 * in this case, the patterns are applied after
+		 * prefixes like "refs/heads/" etc. are stripped off,
+		 * so we have to look at everything:
+		 */
+		return for_each_fullref_in("", cb, cb_data, broken);
+	}
+
+	if (filter->ignore_case) {
+		/*
+		 * we can't handle case-insensitive comparisons,
+		 * so just return everything and let the caller
+		 * sort it out.
+		 */
+		return for_each_fullref_in("", cb, cb_data, broken);
+	}
+
+	if (!filter->name_patterns[0]) {
+		/* no patterns; we have to look at everything */
+		return for_each_fullref_in("", cb, cb_data, broken);
+	}
+
+	find_longest_prefixes(&prefixes, filter->name_patterns);
+
+	for_each_string_list_item(prefix, &prefixes) {
+		ret = for_each_fullref_in(prefix->string, cb, cb_data, broken);
+		if (ret)
+			break;
+	}
+
+	string_list_clear(&prefixes, 0);
+	return ret;
+}
+
+/*
+ * Given a ref (sha1, refname), check if the ref belongs to the array
+ * of sha1s. If the given ref is a tag, check if the given tag points
+ * at one of the sha1s in the given sha1 array.
+ * the given sha1_array.
+ * NEEDSWORK:
+ * 1. Only a single level of inderection is obtained, we might want to
+ * change this to account for multiple levels (e.g. annotated tags
+ * pointing to annotated tags pointing to a commit.)
+ * 2. As the refs are cached we might know what refname peels to without
+ * the need to parse the object via parse_object(). peel_ref() might be a
+ * more efficient alternative to obtain the pointee.
+ */
+static const struct object_id *match_points_at(struct oid_array *points_at,
+					       const struct object_id *oid,
+					       const char *refname)
+{
+	const struct object_id *tagged_oid = NULL;
+	struct object *obj;
+
+	if (oid_array_lookup(points_at, oid) >= 0)
+		return oid;
+	obj = parse_object(the_repository, oid);
+	if (!obj)
+		die(_("malformed object at '%s'"), refname);
+	if (obj->type == OBJ_TAG)
+		tagged_oid = &((struct tag *)obj)->tagged->oid;
+	if (tagged_oid && oid_array_lookup(points_at, tagged_oid) >= 0)
+		return tagged_oid;
+	return NULL;
+}
+
+/*
+ * Allocate space for a new ref_array_item and copy the name and oid to it.
+ *
+ * Callers can then fill in other struct members at their leisure.
+ */
+static struct ref_array_item *new_ref_array_item(const char *refname,
+						 const struct object_id *oid)
+{
+	struct ref_array_item *ref;
+
+	FLEX_ALLOC_STR(ref, refname, refname);
+	oidcpy(&ref->objectname, oid);
+
+	return ref;
+}
+
+struct ref_array_item *ref_array_push(struct ref_array *array,
+				      const char *refname,
+				      const struct object_id *oid)
+{
+	struct ref_array_item *ref = new_ref_array_item(refname, oid);
+
+	ALLOC_GROW(array->items, array->nr + 1, array->alloc);
+	array->items[array->nr++] = ref;
+
+	return ref;
+}
+
+static int ref_kind_from_refname(const char *refname)
+{
+	unsigned int i;
+
+	static struct {
+		const char *prefix;
+		unsigned int kind;
+	} ref_kind[] = {
+		{ "refs/heads/" , FILTER_REFS_BRANCHES },
+		{ "refs/remotes/" , FILTER_REFS_REMOTES },
+		{ "refs/tags/", FILTER_REFS_TAGS}
+	};
+
+	if (!strcmp(refname, "HEAD"))
+		return FILTER_REFS_DETACHED_HEAD;
+
+	for (i = 0; i < ARRAY_SIZE(ref_kind); i++) {
+		if (starts_with(refname, ref_kind[i].prefix))
+			return ref_kind[i].kind;
+	}
+
+	return FILTER_REFS_OTHERS;
+}
+
+static int filter_ref_kind(struct ref_filter *filter, const char *refname)
+{
+	if (filter->kind == FILTER_REFS_BRANCHES ||
+	    filter->kind == FILTER_REFS_REMOTES ||
+	    filter->kind == FILTER_REFS_TAGS)
+		return filter->kind;
+	return ref_kind_from_refname(refname);
+}
+
+struct ref_filter_cbdata {
+	struct ref_array *array;
+	struct ref_filter *filter;
+	struct contains_cache contains_cache;
+	struct contains_cache no_contains_cache;
+};
+
+/*
+ * A call-back given to for_each_ref().  Filter refs and keep them for
+ * later object processing.
+ */
+static int ref_filter_handler(const char *refname, const struct object_id *oid, int flag, void *cb_data)
+{
+	struct ref_filter_cbdata *ref_cbdata = cb_data;
+	struct ref_filter *filter = ref_cbdata->filter;
+	struct ref_array_item *ref;
+	struct commit *commit = NULL;
+	unsigned int kind;
+
+	if (flag & REF_BAD_NAME) {
+		warning(_("ignoring ref with broken name %s"), refname);
+		return 0;
+	}
+
+	if (flag & REF_ISBROKEN) {
+		warning(_("ignoring broken ref %s"), refname);
+		return 0;
+	}
+
+	/* Obtain the current ref kind from filter_ref_kind() and ignore unwanted refs. */
+	kind = filter_ref_kind(filter, refname);
+	if (!(kind & filter->kind))
+		return 0;
+
+	if (!filter_pattern_match(filter, refname))
+		return 0;
+
+	if (filter->points_at.nr && !match_points_at(&filter->points_at, oid, refname))
+		return 0;
+
+	/*
+	 * A merge filter is applied on refs pointing to commits. Hence
+	 * obtain the commit using the 'oid' available and discard all
+	 * non-commits early. The actual filtering is done later.
+	 */
+	if (filter->merge_commit || filter->with_commit || filter->no_commit || filter->verbose) {
+		commit = lookup_commit_reference_gently(the_repository, oid,
+							1);
+		if (!commit)
+			return 0;
+		/* We perform the filtering for the '--contains' option... */
+		if (filter->with_commit &&
+		    !commit_contains(filter, commit, filter->with_commit, &ref_cbdata->contains_cache))
+			return 0;
+		/* ...or for the `--no-contains' option */
+		if (filter->no_commit &&
+		    commit_contains(filter, commit, filter->no_commit, &ref_cbdata->no_contains_cache))
+			return 0;
+	}
+
+	/*
+	 * We do not open the object yet; sort may only need refname
+	 * to do its job and the resulting list may yet to be pruned
+	 * by maxcount logic.
+	 */
+	ref = ref_array_push(ref_cbdata->array, refname, oid);
+	ref->commit = commit;
+	ref->flag = flag;
+	ref->kind = kind;
+
+	return 0;
+}
+
+/*  Free memory allocated for a ref_array_item */
+static void free_array_item(struct ref_array_item *item)
+{
+	free((char *)item->symref);
+	if (item->value) {
+		int i;
+		for (i = 0; i < used_atom_cnt; i++)
+			free((char *)item->value[i].s);
+		free(item->value);
+	}
+	free(item);
+}
+
+/* Free all memory allocated for ref_array */
+void ref_array_clear(struct ref_array *array)
+{
+	int i;
+
+	for (i = 0; i < array->nr; i++)
+		free_array_item(array->items[i]);
+	FREE_AND_NULL(array->items);
+	array->nr = array->alloc = 0;
+
+	for (i = 0; i < used_atom_cnt; i++)
+		free((char *)used_atom[i].name);
+	FREE_AND_NULL(used_atom);
+	used_atom_cnt = 0;
+
+	if (ref_to_worktree_map.worktrees) {
+		hashmap_free(&(ref_to_worktree_map.map), 1);
+		free_worktrees(ref_to_worktree_map.worktrees);
+		ref_to_worktree_map.worktrees = NULL;
+	}
+}
+
+static void do_merge_filter(struct ref_filter_cbdata *ref_cbdata)
+{
+	struct rev_info revs;
+	int i, old_nr;
+	struct ref_filter *filter = ref_cbdata->filter;
+	struct ref_array *array = ref_cbdata->array;
+	struct commit **to_clear = xcalloc(sizeof(struct commit *), array->nr);
+
+	repo_init_revisions(the_repository, &revs, NULL);
+
+	for (i = 0; i < array->nr; i++) {
+		struct ref_array_item *item = array->items[i];
+		add_pending_object(&revs, &item->commit->object, item->refname);
+		to_clear[i] = item->commit;
+	}
+
+	filter->merge_commit->object.flags |= UNINTERESTING;
+	add_pending_object(&revs, &filter->merge_commit->object, "");
+
+	revs.limited = 1;
+	if (prepare_revision_walk(&revs))
+		die(_("revision walk setup failed"));
+
+	old_nr = array->nr;
+	array->nr = 0;
+
+	for (i = 0; i < old_nr; i++) {
+		struct ref_array_item *item = array->items[i];
+		struct commit *commit = item->commit;
+
+		int is_merged = !!(commit->object.flags & UNINTERESTING);
+
+		if (is_merged == (filter->merge == REF_FILTER_MERGED_INCLUDE))
+			array->items[array->nr++] = array->items[i];
+		else
+			free_array_item(item);
+	}
+
+	clear_commit_marks_many(old_nr, to_clear, ALL_REV_FLAGS);
+	clear_commit_marks(filter->merge_commit, ALL_REV_FLAGS);
+	free(to_clear);
+}
+
+/*
+ * API for filtering a set of refs. Based on the type of refs the user
+ * has requested, we iterate through those refs and apply filters
+ * as per the given ref_filter structure and finally store the
+ * filtered refs in the ref_array structure.
+ */
+int filter_refs(struct ref_array *array, struct ref_filter *filter, unsigned int type)
+{
+	struct ref_filter_cbdata ref_cbdata;
+	int ret = 0;
+	unsigned int broken = 0;
+
+	ref_cbdata.array = array;
+	ref_cbdata.filter = filter;
+
+	if (type & FILTER_REFS_INCLUDE_BROKEN)
+		broken = 1;
+	filter->kind = type & FILTER_REFS_KIND_MASK;
+
+	init_contains_cache(&ref_cbdata.contains_cache);
+	init_contains_cache(&ref_cbdata.no_contains_cache);
+
+	/*  Simple per-ref filtering */
+	if (!filter->kind)
+		die("filter_refs: invalid type");
+	else {
+		/*
+		 * For common cases where we need only branches or remotes or tags,
+		 * we only iterate through those refs. If a mix of refs is needed,
+		 * we iterate over all refs and filter out required refs with the help
+		 * of filter_ref_kind().
+		 */
+		if (filter->kind == FILTER_REFS_BRANCHES)
+			ret = for_each_fullref_in("refs/heads/", ref_filter_handler, &ref_cbdata, broken);
+		else if (filter->kind == FILTER_REFS_REMOTES)
+			ret = for_each_fullref_in("refs/remotes/", ref_filter_handler, &ref_cbdata, broken);
+		else if (filter->kind == FILTER_REFS_TAGS)
+			ret = for_each_fullref_in("refs/tags/", ref_filter_handler, &ref_cbdata, broken);
+		else if (filter->kind & FILTER_REFS_ALL)
+			ret = for_each_fullref_in_pattern(filter, ref_filter_handler, &ref_cbdata, broken);
+		if (!ret && (filter->kind & FILTER_REFS_DETACHED_HEAD))
+			head_ref(ref_filter_handler, &ref_cbdata);
+	}
+
+	clear_contains_cache(&ref_cbdata.contains_cache);
+	clear_contains_cache(&ref_cbdata.no_contains_cache);
+
+	/*  Filters that need revision walking */
+	if (filter->merge_commit)
+		do_merge_filter(&ref_cbdata);
+
+	return ret;
+}
+
+static int cmp_ref_sorting(struct ref_sorting *s, struct ref_array_item *a, struct ref_array_item *b)
+{
+	struct atom_value *va, *vb;
+	int cmp;
+	cmp_type cmp_type = used_atom[s->atom].type;
+	int (*cmp_fn)(const char *, const char *);
+	struct strbuf err = STRBUF_INIT;
+
+	if (get_ref_atom_value(a, s->atom, &va, &err))
+		die("%s", err.buf);
+	if (get_ref_atom_value(b, s->atom, &vb, &err))
+		die("%s", err.buf);
+	strbuf_release(&err);
+	cmp_fn = s->ignore_case ? strcasecmp : strcmp;
+	if (s->version)
+		cmp = versioncmp(va->s, vb->s);
+	else if (cmp_type == FIELD_STR)
+		cmp = cmp_fn(va->s, vb->s);
+	else {
+		if (va->value < vb->value)
+			cmp = -1;
+		else if (va->value == vb->value)
+			cmp = cmp_fn(a->refname, b->refname);
+		else
+			cmp = 1;
+	}
+
+	return (s->reverse) ? -cmp : cmp;
+}
+
+static int compare_refs(const void *a_, const void *b_, void *ref_sorting)
+{
+	struct ref_array_item *a = *((struct ref_array_item **)a_);
+	struct ref_array_item *b = *((struct ref_array_item **)b_);
+	struct ref_sorting *s;
+
+	for (s = ref_sorting; s; s = s->next) {
+		int cmp = cmp_ref_sorting(s, a, b);
+		if (cmp)
+			return cmp;
+	}
+	return 0;
+}
+
+void ref_array_sort(struct ref_sorting *sorting, struct ref_array *array)
+{
+	QSORT_S(array->items, array->nr, compare_refs, sorting);
+}
+
+static void append_literal(const char *cp, const char *ep, struct ref_formatting_state *state)
+{
+	struct strbuf *s = &state->stack->output;
+
+	while (*cp && (!ep || cp < ep)) {
+		if (*cp == '%') {
+			if (cp[1] == '%')
+				cp++;
+			else {
+				int ch = hex2chr(cp + 1);
+				if (0 <= ch) {
+					strbuf_addch(s, ch);
+					cp += 3;
+					continue;
+				}
+			}
+		}
+		strbuf_addch(s, *cp);
+		cp++;
+	}
+}
+
+int format_ref_array_item(struct ref_array_item *info,
+			   const struct ref_format *format,
+			   struct strbuf *final_buf,
+			   struct strbuf *error_buf)
+{
+	const char *cp, *sp, *ep;
+	struct ref_formatting_state state = REF_FORMATTING_STATE_INIT;
+
+	state.quote_style = format->quote_style;
+	push_stack_element(&state.stack);
+
+	for (cp = format->format; *cp && (sp = find_next(cp)); cp = ep + 1) {
+		struct atom_value *atomv;
+		int pos;
+
+		ep = strchr(sp, ')');
+		if (cp < sp)
+			append_literal(cp, sp, &state);
+		pos = parse_ref_filter_atom(format, sp + 2, ep, error_buf);
+		if (pos < 0 || get_ref_atom_value(info, pos, &atomv, error_buf) ||
+		    atomv->handler(atomv, &state, error_buf)) {
+			pop_stack_element(&state.stack);
+			return -1;
+		}
+	}
+	if (*cp) {
+		sp = cp + strlen(cp);
+		append_literal(cp, sp, &state);
+	}
+	if (format->need_color_reset_at_eol) {
+		struct atom_value resetv;
+		resetv.s = GIT_COLOR_RESET;
+		if (append_atom(&resetv, &state, error_buf)) {
+			pop_stack_element(&state.stack);
+			return -1;
+		}
+	}
+	if (state.stack->prev) {
+		pop_stack_element(&state.stack);
+		return strbuf_addf_ret(error_buf, -1, _("format: %%(end) atom missing"));
+	}
+	strbuf_addbuf(final_buf, &state.stack->output);
+	pop_stack_element(&state.stack);
+	return 0;
+}
+
+void show_ref_array_item(struct ref_array_item *info,
+			 const struct ref_format *format)
+{
+	struct strbuf final_buf = STRBUF_INIT;
+	struct strbuf error_buf = STRBUF_INIT;
+
+	if (format_ref_array_item(info, format, &final_buf, &error_buf))
+		die("%s", error_buf.buf);
+	fwrite(final_buf.buf, 1, final_buf.len, stdout);
+	strbuf_release(&error_buf);
+	strbuf_release(&final_buf);
+	putchar('\n');
+}
+
+void pretty_print_ref(const char *name, const struct object_id *oid,
+		      const struct ref_format *format)
+{
+	struct ref_array_item *ref_item;
+	ref_item = new_ref_array_item(name, oid);
+	ref_item->kind = ref_kind_from_refname(name);
+	show_ref_array_item(ref_item, format);
+	free_array_item(ref_item);
+}
+
+static int parse_sorting_atom(const char *atom)
+{
+	/*
+	 * This parses an atom using a dummy ref_format, since we don't
+	 * actually care about the formatting details.
+	 */
+	struct ref_format dummy = REF_FORMAT_INIT;
+	const char *end = atom + strlen(atom);
+	struct strbuf err = STRBUF_INIT;
+	int res = parse_ref_filter_atom(&dummy, atom, end, &err);
+	if (res < 0)
+		die("%s", err.buf);
+	strbuf_release(&err);
+	return res;
+}
+
+/*  If no sorting option is given, use refname to sort as default */
+struct ref_sorting *ref_default_sorting(void)
+{
+	static const char cstr_name[] = "refname";
+
+	struct ref_sorting *sorting = xcalloc(1, sizeof(*sorting));
+
+	sorting->next = NULL;
+	sorting->atom = parse_sorting_atom(cstr_name);
+	return sorting;
+}
+
+void parse_ref_sorting(struct ref_sorting **sorting_tail, const char *arg)
+{
+	struct ref_sorting *s;
+
+	s = xcalloc(1, sizeof(*s));
+	s->next = *sorting_tail;
+	*sorting_tail = s;
+
+	if (*arg == '-') {
+		s->reverse = 1;
+		arg++;
+	}
+	if (skip_prefix(arg, "version:", &arg) ||
+	    skip_prefix(arg, "v:", &arg))
+		s->version = 1;
+	s->atom = parse_sorting_atom(arg);
+}
+
+int parse_opt_ref_sorting(const struct option *opt, const char *arg, int unset)
+{
+	/*
+	 * NEEDSWORK: We should probably clear the list in this case, but we've
+	 * already munged the global used_atoms list, which would need to be
+	 * undone.
+	 */
+	BUG_ON_OPT_NEG(unset);
+
+	parse_ref_sorting(opt->value, arg);
+	return 0;
+}
+
+int parse_opt_merge_filter(const struct option *opt, const char *arg, int unset)
+{
+	struct ref_filter *rf = opt->value;
+	struct object_id oid;
+	int no_merged = starts_with(opt->long_name, "no");
+
+	BUG_ON_OPT_NEG(unset);
+
+	if (rf->merge) {
+		if (no_merged) {
+			return error(_("option `%s' is incompatible with --merged"),
+				     opt->long_name);
+		} else {
+			return error(_("option `%s' is incompatible with --no-merged"),
+				     opt->long_name);
+		}
+	}
+
+	rf->merge = no_merged
+		? REF_FILTER_MERGED_OMIT
+		: REF_FILTER_MERGED_INCLUDE;
+
+	if (get_oid(arg, &oid))
+		die(_("malformed object name %s"), arg);
+
+	rf->merge_commit = lookup_commit_reference_gently(the_repository,
+							  &oid, 0);
+	if (!rf->merge_commit)
+		return error(_("option `%s' must point to a commit"), opt->long_name);
+
+	return 0;
+}