Add "git show-ref" builtin command

Add "git show-ref" builtin command

[Linus Torvalds]

It's kind of like "git peek-remote", but works only locally (and thus 
avoids the whole overhead of git_connect()) and has some extra 
verification features.

For example, it allows you to filter the results, and to choose whether 
you want the tag dereferencing or not. You can also use it to just test 
whether a particular ref exists.

For example:

	git show-ref master

will show all references called "master", whether tags or heads or 
anything else, and regardless of how deep in the reference naming 
hierarchy they are (so it would show "refs/heads/master" but also 
"refs/remote/other-repo/master").

When using the "--verify" flag, the command requires an exact ref path:

	git show-ref --verify refs/heads/master

will only match the exact branch called "master".

If nothing matches, show-ref will return an error code of 1, and in the 
case of verification, it will show an error message.

For scripting, you can ask it to be quiet with the "--quiet" flag, which 
allows you to do things like

	git-show-ref --quiet --verify -- "refs/heads/$headname" ||
		echo "$headname is not a valid branch"

to check whether a particular branch exists or not (notice how we don't 
actually want to show any results, and we want to use the full refname for 
it in order to not trigger the problem with ambiguous partial matches).

To show only tags, or only proper branch heads, use "--tags" and/or 
"--heads" respectively (using both means that it shows tags _and_ heads, 
but not other random references under the refs/ subdirectory).

To do automatic tag object dereferencing, use the "-d" or "--dereference" 
flag, so you can do

	git show-ref --tags --dereference

to get a listing of all tags together with what they dereference.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

NOTE! This is against the current master branch, and does _not_ depend on 
my other ref-work. In fact, I'd argue that this is much better to merge 
first and independently of the packed references branch, because it allows 
us to much more easily update the scripts etc to be totally unaware of how 
the refs are actually stored.

I've given it some basic testing, and it all seems obvious enough.

diff --git a/Makefile b/Makefile
index 7b3114f..c365138 100644
--- a/Makefile
+++ b/Makefile
@@ -295,7 +295,8 @@ BUILTIN_OBJS = \
 	builtin-upload-tar.o \
 	builtin-verify-pack.o \
 	builtin-write-tree.o \
-	builtin-zip-tree.o
+	builtin-zip-tree.o \
+	builtin-show-ref.o
 
 GITLIBS = $(LIB_FILE) $(XDIFF_LIB)
 LIBS = $(GITLIBS) -lz
diff --git a/builtin-show-ref.c b/builtin-show-ref.c
new file mode 100644
index 0000000..161b236
--- /dev/null
+++ b/builtin-show-ref.c
@@ -0,0 +1,112 @@
+#include "cache.h"
+#include "refs.h"
+#include "object.h"
+#include "tag.h"
+
+static const char show_ref_usage[] = "git show-ref [-q|--quiet] [--verify] [-h|--head] [-d|--deref] [--tags] [--heads] [--] [pattern*]";
+
+static int deref_tags = 0, show_head = 0, tags_only = 0, heads_only = 0, found_match = 0, verify = 0, quiet = 0;
+static const char **pattern;
+
+static int show_ref(const char *refname, const unsigned char *sha1)
+{
+	struct object *obj;
+
+	if (tags_only || heads_only) {
+		int match;
+
+		match = heads_only && !strncmp(refname, "refs/heads/", 11);
+		match |= tags_only && !strncmp(refname, "refs/tags/", 10);
+		if (!match)
+			return 0;
+	}
+	if (pattern) {
+		int reflen = strlen(refname);
+		const char **p = pattern, *m;
+		while ((m = *p++) != NULL) {
+			int len = strlen(m);
+			if (len > reflen)
+				continue;
+			if (memcmp(m, refname + reflen - len, len))
+				continue;
+			if (len == reflen)
+				goto match;
+			/* "--verify" requires an exact match */
+			if (verify)
+				continue;
+			if (refname[reflen - len - 1] == '/')
+				goto match;
+		}
+		return 0;
+	}
+
+match:
+	found_match++;
+	obj = parse_object(sha1);
+	if (!obj) {
+		if (quiet)
+			return 0;
+		die("git-show-ref: bad ref %s (%s)", refname, sha1_to_hex(sha1));
+	}
+	if (quiet)
+		return 0;
+	printf("%s %s\n", sha1_to_hex(sha1), refname);
+	if (deref_tags && obj->type == OBJ_TAG) {
+		obj = deref_tag(obj, refname, 0);
+		printf("%s %s^{}\n", sha1_to_hex(obj->sha1), refname);
+	}
+	return 0;
+}
+
+int cmd_show_ref(int argc, const char **argv, const char *prefix)
+{
+	int i;
+
+	for (i = 1; i < argc; i++) {
+		const char *arg = argv[i];
+		if (*arg != '-') {
+			pattern = argv + i;
+			break;
+		}
+		if (!strcmp(arg, "--")) {
+			pattern = argv + i + 1;
+			if (!*pattern)
+				pattern = NULL;
+			break;
+		}
+		if (!strcmp(arg, "-q") || !strcmp(arg, "--quiet")) {
+			quiet = 1;
+			continue;
+		}
+		if (!strcmp(arg, "-h") || !strcmp(arg, "--head")) {
+			show_head = 1;
+			continue;
+		}
+		if (!strcmp(arg, "-d") || !strcmp(arg, "--dereference")) {
+			deref_tags = 1;
+			continue;
+		}
+		if (!strcmp(arg, "--verify")) {
+			verify = 1;
+			continue;
+		}
+		if (!strcmp(arg, "--tags")) {
+			tags_only = 1;
+			continue;
+		}
+		if (!strcmp(arg, "--heads")) {
+			heads_only = 1;
+			continue;
+		}
+		usage(show_ref_usage);
+	}
+	if (show_head)
+		head_ref(show_ref);
+	for_each_ref(show_ref);
+	if (!found_match) {
+		if (verify && !quiet)
+			die("No match");
+		return 1;
+	}
+	return 0;
+}
diff --git a/builtin.h b/builtin.h
index 25431d7..bca5f79 100644
--- a/builtin.h
+++ b/builtin.h
@@ -61,5 +61,6 @@ extern int cmd_version(int argc, const c
 extern int cmd_whatchanged(int argc, const char **argv, const char *prefix);
 extern int cmd_write_tree(int argc, const char **argv, const char *prefix);
 extern int cmd_verify_pack(int argc, const char **argv, const char *prefix);
+extern int cmd_show_ref(int argc, const char **argv, const char *prefix);
 
 #endif
diff --git a/git.c b/git.c
index 8c182a5..fedd536 100644
--- a/git.c
+++ b/git.c
@@ -266,6 +266,7 @@ static void handle_internal_command(int 
 		{ "whatchanged", cmd_whatchanged, RUN_SETUP | USE_PAGER },
 		{ "write-tree", cmd_write_tree, RUN_SETUP },
 		{ "verify-pack", cmd_verify_pack },
+		{ "show-ref", cmd_show_ref, RUN_SETUP },
 	};
 	int i;
 

Re: Add "git show-ref" builtin command

[Junio C Hamano]

Linus Torvalds <torvalds@osdl.org> writes:

> It's kind of like "git peek-remote", but works only locally (and thus 
> avoids the whole overhead of git_connect()) and has some extra 
> verification features.
>...
> NOTE! This is against the current master branch, and does _not_ depend on 
> my other ref-work. In fact, I'd argue that this is much better to merge 
> first and independently of the packed references branch, because it allows 
> us to much more easily update the scripts etc to be totally unaware of how 
> the refs are actually stored.

Looks sane.  Thanks.

Having said that....

Gaaah.  I had been doing a "show-refs" that does something quite
different from this X-<.

I'll rename it; I think the new name makes more sense anyway.

-- >8 --
From: Junio C Hamano <junkio@cox.net>
Date: Fri, 15 Sep 2006 13:30:02 -0700
Subject: [PATCH] Add git-for-each-ref: helper for language bindings

This adds a new command, git-for-each-ref.  You can have it iterate
over refs and have it output various aspects of the objects they
refer to.

Signed-off-by: Junio C Hamano <junkio@cox.net>
---
 .gitignore                         |    1 
 Documentation/git-for-each-ref.txt |  164 +++++++
 Makefile                           |    1 
 builtin-for-each-ref.c             |  845 ++++++++++++++++++++++++++++++++++++
 builtin.h                          |    3 
 git.c                              |    1 
 object.c                           |   68 ++-
 object.h                           |    6 
 quote.c                            |   38 ++
 quote.h                            |    4 
 10 files changed, 1103 insertions(+), 28 deletions(-)

diff --git a/.gitignore b/.gitignore
index 0d608fe..0b08f37 100644
--- a/.gitignore
+++ b/.gitignore
@@ -36,6 +36,7 @@ git-fetch
 git-fetch-pack
 git-findtags
 git-fmt-merge-msg
+git-for-each-ref
 git-format-patch
 git-fsck-objects
 git-get-tar-commit-id
diff --git a/Documentation/git-for-each-ref.txt b/Documentation/git-for-each-ref.txt
new file mode 100644
index 0000000..74dd735
--- /dev/null
+++ b/Documentation/git-for-each-ref.txt
@@ -0,0 +1,164 @@
+git-for-each-ref(1)
+===================
+
+NAME
+----
+git-for-each-ref - Output information on each ref
+
+SYNOPSIS
+--------
+'git-for-each-ref' [--count=<count>]* [--shell|--perl|--python] [--sort=<key>]* [--format=<format>] [<pattern>]
+
+DESCRIPTION
+-----------
+
+Iterate over all refs that match `<pattern>` and show them
+according to the given `<format>`, after sorting them according
+to the given `<sortkeys>`.  If `<max>` is given, stop after
+showing that many refs.  The interporated values in `<format>`
+can optionally be quoted as string literals in the specified
+host language.
+
+OPTIONS
+-------
+<count>::
+	By default the command shows all refs that match
+	`<pattern>`.  This option makes it stop after showing
+	that many refs.
+
+<key>::
+	A field name to sort on.  Prefix `-` to sort in
+	descending order of the value.  When unspecified,
+	`refname` is used.  More than one sort keys can be
+	given.
+
+<format>::
+	A string that interpolates `%(fieldname)` from the
+	object pointed at by a ref being shown.  If `fieldname`
+	is prefixed with an asterisk (`*`) and the ref points
+	at a tag object, the value for the field in the object
+	tag refers is used.  When unspecified, defaults to
+	`%(refname)`.
+
+<pattern>::
+	If given, the name of the ref is matched against this
+	using fnmatch(3).  Refs that do not match the pattern
+	are not shown.
+
+--shell, --perl, --python::
+	If given, strings that substitute `%(fieldname)`
+	placeholders are quoted as string literals suitable for
+	the specified host language.  This is meant to produce
+	a scriptlet that can directly be `eval`ed.
+
+
+FIELD NAMES
+-----------
+
+Various values from structured fields in referenced objects can
+be used to interpolate into the resulting output, or as sort
+keys.
+
+For all objects, the following names can be used:
+
+refname::
+	The name of the ref (the part after $GIT_DIR/refs/).
+
+objecttype::
+	The type of the object (`blob`, `tree`, `commit`, `tag`).
+
+objectsize::
+	The size of the object (the same as `git-cat-file -s` reports).
+
+objectname::
+	The object name (aka SHA-1).
+
+In addition to the above, for commit and tag objects, the header
+field names (`tree`, `parent`, `object`, `type`, and `tag`) can
+be used to specify the value in the header field.
+
+Fields that have name-email-date tuple as its value (`author`,
+`committer`, and `tagger`) can be suffixed with `name`, `email`,
+and `date` to extract the named component.
+
+The first line of the message in a commit and tag object is
+`subject`, the remaining lines are `body`.  The whole message
+is `contents`.
+
+For sorting purposes, fields with numeric values sort in numeric
+order (`objectsize`, `authordate`, `committerdate`, `taggerdate`).
+All other fields are used to sort in their byte-value order.
+
+In any case, a field name that refers to a field inapplicable to
+the object referred by the ref does not cause an error.  It
+returns an empty string instead.
+
+
+EXAMPLES
+--------
+
+Show the most recent 3 tagged commits::
+
+------------
+#!/bin/sh
+
+git-for-each-ref --count=3 --sort='-*authordate' \
+--format='From: %(*authorname) %(*authoremail)
+Subject: %(*subject)
+Date: %(*authordate)
+Ref: %(*refname)
+
+%(*body)
+' 'refs/tags'
+------------
+
+A bit more elaborate report on tags::
+------------
+#!/bin/sh
+
+fmt='
+	r=%(refname)
+	t=%(*objecttype)
+	T=${r#refs/tags/}
+
+	o=%(*objectname)
+	n=%(*authorname)
+	e=%(*authoremail)
+	s=%(*subject)
+	d=%(*authordate)
+	b=%(*body)
+
+	kind=Tag
+	if test "z$t" = z
+	then
+		# could be a lightweight tag
+		t=%(objecttype)
+		kind="Lightweight tag"
+		o=%(objectname)
+		n=%(authorname)
+		e=%(authoremail)
+		s=%(subject)
+		d=%(authordate)
+		b=%(body)
+	fi
+	echo "$kind $T points at a $t object $o"
+	if test "z$t" = zcommit
+	then
+		echo "The commit was authored by $n $e
+at $d, and titled
+
+    $s
+
+Its message reads as:
+"
+		echo "$b" | sed -e "s/^/    /"
+		echo
+	fi
+'
+
+eval=`git-for-each-ref -s --format="$fmt" \
+	--sort='*objecttype' \
+	--sort=-taggerdate \
+	refs/tags`
+eval "$eval"
+------------
diff --git a/Makefile b/Makefile
index 7b3114f..f0e2e51 100644
--- a/Makefile
+++ b/Makefile
@@ -267,6 +267,7 @@ BUILTIN_OBJS = \
 	builtin-diff-stages.o \
 	builtin-diff-tree.o \
 	builtin-fmt-merge-msg.o \
+	builtin-for-each-ref.o \
 	builtin-grep.o \
 	builtin-init-db.o \
 	builtin-log.o \
diff --git a/builtin-for-each-ref.c b/builtin-for-each-ref.c
new file mode 100644
index 0000000..f064e7e
--- /dev/null
+++ b/builtin-for-each-ref.c
@@ -0,0 +1,845 @@
+#include "cache.h"
+#include "refs.h"
+#include "object.h"
+#include "tag.h"
+#include "commit.h"
+#include "tree.h"
+#include "blob.h"
+#include "quote.h"
+#include <fnmatch.h>
+
+/* Quoting styles */
+#define QUOTE_NONE 0
+#define QUOTE_SHELL 1
+#define QUOTE_PERL 2
+#define QUOTE_PYTHON 3
+
+typedef enum { FIELD_STR, FIELD_ULONG, FIELD_TIME } cmp_type;
+
+struct atom_value {
+	const char *s;
+	unsigned long ul; /* used for sorting when not FIELD_STR */
+};
+
+struct ref_sort {
+	struct ref_sort *next;
+	int atom; /* index into used_atom array */
+	unsigned reverse : 1;
+};
+
+struct refinfo {
+	char *refname;
+	unsigned char objectname[20];
+	struct atom_value *value;
+};
+
+static struct {
+	const char *name;
+	cmp_type cmp_type;
+} valid_atom[] = {
+	{ "refname" },
+	{ "objecttype" },
+	{ "objectsize", FIELD_ULONG },
+	{ "objectname" },
+	{ "tree" },
+	{ "parent" }, /* NEEDSWORK: how to address 2nd and later parents? */
+	{ "numparent", FIELD_ULONG },
+	{ "object" },
+	{ "type" },
+	{ "tag" },
+	{ "author" },
+	{ "authorname" },
+	{ "authoremail" },
+	{ "authordate", FIELD_TIME },
+	{ "committer" },
+	{ "committername" },
+	{ "committeremail" },
+	{ "committerdate", FIELD_TIME },
+	{ "tagger" },
+	{ "taggername" },
+	{ "taggeremail" },
+	{ "taggerdate", FIELD_TIME },
+	{ "subject" },
+	{ "body" },
+	{ "contents" },
+};
+
+/*
+ * An atom is a valid field atom listed above, 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.  refinfo
+ * structure will hold an array of values extracted that can be
+ * indexed with the "atom number", which is an index into this
+ * array.
+ */
+static const char **used_atom;
+static cmp_type *used_atom_type;
+static int used_atom_cnt, sort_atom_limit, need_tagged;
+
+/*
+ * Used to parse format string and sort specifiers
+ */
+static int parse_atom(const char *atom, const char *ep)
+{
+	const char *sp;
+	char *n;
+	int i, at;
+
+	sp = atom;
+	if (*sp == '*' && sp < ep)
+		sp++; /* deref */
+	if (ep <= sp)
+		die("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]);
+		if (len == ep - atom && !memcmp(used_atom[i], atom, len))
+			return i;
+	}
+
+	/* Is the atom a valid one? */
+	for (i = 0; i < ARRAY_SIZE(valid_atom); i++) {
+		int len = strlen(valid_atom[i].name);
+		if (len == ep - sp && !memcmp(valid_atom[i].name, sp, len))
+			break;
+	}
+
+	if (ARRAY_SIZE(valid_atom) <= i)
+		die("unknown field name: %.*s", (int)(ep-atom), atom);
+
+	/* Add it in, including the deref prefix */
+	at = used_atom_cnt;
+	used_atom_cnt++;
+	used_atom = xrealloc(used_atom,
+			     (sizeof *used_atom) * used_atom_cnt);
+	used_atom_type = xrealloc(used_atom_type,
+				  (sizeof(*used_atom_type) * used_atom_cnt));
+	n = xmalloc(ep - atom + 1);
+	memcpy(n, atom, ep - atom);
+	n[ep-atom] = 0;
+	used_atom[at] = n;
+	used_atom_type[at] = valid_atom[i].cmp_type;
+	return at;
+}
+
+/*
+ * 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 quoteed 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.
+ */
+static void verify_format(const char *format)
+{
+	const char *cp, *sp;
+	for (cp = format; *cp && (sp = find_next(cp)); ) {
+		const char *ep = strchr(sp, ')');
+		if (!ep)
+			die("malformatted format string %s", sp);
+		/* sp points at "%(" and ep points at the closing ")" */
+		parse_atom(sp + 2, ep);
+		cp = ep + 1;
+	}
+}
+
+/*
+ * Given an object name, read the object data and size, and return a
+ * "struct object".  If the object data we are returning is also borrowed
+ * by the "struct object" representation, set *eaten as well---it is a
+ * signal from parse_object_buffer to us not to free the buffer.
+ */
+static void *get_obj(const unsigned char *sha1, struct object **obj, unsigned long *sz, int *eaten)
+{
+	char type[20];
+	void *buf = read_sha1_file(sha1, type, sz);
+
+	if (buf)
+		*obj = parse_object_buffer(sha1, type, *sz, buf, eaten);
+	else
+		*obj = NULL;
+	return buf;
+}
+
+/* See grab_values */
+static void grab_common_values(struct atom_value *val, int deref, struct object *obj, void *buf, unsigned long sz)
+{
+	int i;
+
+	for (i = 0; i < used_atom_cnt; i++) {
+		const char *name = used_atom[i];
+		struct atom_value *v = &val[i];
+		if (!!deref != (*name == '*'))
+			continue;
+		if (deref)
+			name++;
+		if (!strcmp(name, "objecttype"))
+			v->s = type_names[obj->type];
+		else if (!strcmp(name, "objectsize")) {
+			char *s = xmalloc(40);
+			sprintf(s, "%lu", sz);
+			v->ul = sz;
+			v->s = s;
+		}
+		else if (!strcmp(name, "objectname")) {
+			char *s = xmalloc(41);
+			strcpy(s, sha1_to_hex(obj->sha1));
+			v->s = s;
+		}
+	}
+}
+
+/* See grab_values */
+static void grab_tag_values(struct atom_value *val, int deref, struct object *obj, void *buf, unsigned long sz)
+{
+	int i;
+	struct tag *tag = (struct tag *) obj;
+
+	for (i = 0; i < used_atom_cnt; i++) {
+		const char *name = used_atom[i];
+		struct atom_value *v = &val[i];
+		if (!!deref != (*name == '*'))
+			continue;
+		if (deref)
+			name++;
+		if (!strcmp(name, "tag"))
+			v->s = tag->tag;
+	}
+}
+
+static int num_parents(struct commit *commit)
+{
+	struct commit_list *parents;
+	int i;
+
+	for (i = 0, parents = commit->parents;
+	     parents;
+	     parents = parents->next)
+		i++;
+	return i;
+}
+
+/* See grab_values */
+static void grab_commit_values(struct atom_value *val, int deref, struct object *obj, void *buf, unsigned long sz)
+{
+	int i;
+	struct commit *commit = (struct commit *) obj;
+
+	for (i = 0; i < used_atom_cnt; i++) {
+		const char *name = used_atom[i];
+		struct atom_value *v = &val[i];
+		if (!!deref != (*name == '*'))
+			continue;
+		if (deref)
+			name++;
+		if (!strcmp(name, "tree")) {
+			char *s = xmalloc(41);
+			strcpy(s, sha1_to_hex(commit->tree->object.sha1));
+			v->s = s;
+		}
+		if (!strcmp(name, "numparent")) {
+			char *s = xmalloc(40);
+			sprintf(s, "%lu", v->ul);
+			v->s = s;
+			v->ul = num_parents(commit);
+		}
+		else if (!strcmp(name, "parent")) {
+			int num = num_parents(commit);
+			int i;
+			struct commit_list *parents;
+			char *s = xmalloc(42 * num);
+			v->s = s;
+			for (i = 0, parents = commit->parents;
+			     parents;
+			     parents = parents->next, i = i + 42) {
+				struct commit *parent = parents->item;
+				strcpy(s+i, sha1_to_hex(parent->object.sha1));
+				if (parents->next)
+					s[i+40] = ' ';
+			}
+		}
+	}
+}
+
+static const char *find_wholine(const char *who, int wholen, const char *buf, unsigned long sz)
+{
+	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[1] == '\n')
+			return ""; /* end of header */
+		buf = eol;
+	}
+	return "";
+}
+
+static char *copy_line(const char *buf)
+{
+	const char *eol = strchr(buf, '\n');
+	char *line;
+	int len;
+	if (!eol)
+		return "";
+	len = eol - buf;
+	line = xmalloc(len + 1);
+	memcpy(line, buf, len);
+	line[len] = 0;
+	return line;
+}
+
+static char *copy_name(const char *buf)
+{
+	const char *eol = strchr(buf, '\n');
+	const char *eoname = strstr(buf, " <");
+	char *line;
+	int len;
+	if (!(eoname && eol && eoname < eol))
+		return "";
+	len = eoname - buf;
+	line = xmalloc(len + 1);
+	memcpy(line, buf, len);
+	line[len] = 0;
+	return line;
+}
+
+static char *copy_email(const char *buf)
+{
+	const char *email = strchr(buf, '<');
+	const char *eoemail = strchr(email, '>');
+	char *line;
+	int len;
+	if (!email || !eoemail)
+		return "";
+	eoemail++;
+	len = eoemail - email;
+	line = xmalloc(len + 1);
+	memcpy(line, email, len);
+	line[len] = 0;
+	return line;
+}
+
+static void grab_date(const char *buf, struct atom_value *v)
+{
+	const char *eoemail = strstr(buf, "> ");
+	char *zone;
+	unsigned long timestamp;
+	long tz;
+
+	if (!eoemail)
+		goto bad;
+	timestamp = strtoul(eoemail + 2, &zone, 10);
+	if (timestamp == ULONG_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, 0));
+	v->ul = timestamp;
+	return;
+ bad:
+	v->s = "";
+	v->ul = 0;
+}
+
+/* See grab_values */
+static void grab_person(const char *who, struct atom_value *val, int deref, struct object *obj, void *buf, unsigned long sz)
+{
+	int i;
+	int wholen = strlen(who);
+	const char *wholine = NULL;
+
+	for (i = 0; i < used_atom_cnt; i++) {
+		const char *name = used_atom[i];
+		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") &&
+		    strcmp(name + wholen, "date"))
+			continue;
+		if (!wholine)
+			wholine = find_wholine(who, wholen, buf, sz);
+		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 (!strcmp(name + wholen, "date"))
+			grab_date(wholine, v);
+	}
+}
+
+static void find_subpos(const char *buf, unsigned long sz, const char **sub, const char **body)
+{
+	while (*buf) {
+		const char *eol = strchr(buf, '\n');
+		if (!eol)
+			return;
+		if (eol[1] == '\n') {
+			buf = eol + 1;
+			break; /* found end of header */
+		}
+		buf = eol + 1;
+	}
+	while (*buf == '\n')
+		buf++;
+	if (!*buf)
+		return;
+	*sub = buf; /* first non-empty line */
+	buf = strchr(buf, '\n');
+	if (!buf)
+		return; /* no body */
+	while (*buf == '\n')
+		buf++; /* skip blank between subject and body */
+	*body = buf;
+}
+
+/* See grab_values */
+static void grab_sub_body_contents(struct atom_value *val, int deref, struct object *obj, void *buf, unsigned long sz)
+{
+	int i;
+	const char *subpos = NULL, *bodypos = NULL;
+
+	for (i = 0; i < used_atom_cnt; i++) {
+		const char *name = used_atom[i];
+		struct atom_value *v = &val[i];
+		if (!!deref != (*name == '*'))
+			continue;
+		if (deref)
+			name++;
+		if (strcmp(name, "subject") &&
+		    strcmp(name, "body") &&
+		    strcmp(name, "contents"))
+			continue;
+		if (!subpos)
+			find_subpos(buf, sz, &subpos, &bodypos);
+		if (!subpos)
+			return;
+
+		if (!strcmp(name, "subject"))
+			v->s = copy_line(subpos);
+		else if (!strcmp(name, "body"))
+			v->s = bodypos;
+		else if (!strcmp(name, "contents"))
+			v->s = 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 = "";
+	}
+}
+
+/*
+ * 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, unsigned long sz)
+{
+	grab_common_values(val, deref, obj, buf, sz);
+	switch (obj->type) {
+	case OBJ_TAG:
+		grab_tag_values(val, deref, obj, buf, sz);
+		grab_sub_body_contents(val, deref, obj, buf, sz);
+		grab_person("tagger", val, deref, obj, buf, sz);
+		break;
+	case OBJ_COMMIT:
+		grab_commit_values(val, deref, obj, buf, sz);
+		grab_sub_body_contents(val, deref, obj, buf, sz);
+		grab_person("author", val, deref, obj, buf, sz);
+		grab_person("committer", val, deref, obj, buf, sz);
+		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);
+	}
+}
+
+/*
+ * Parse the object referred by ref, and grab needed value.
+ */
+static void populate_value(struct refinfo *ref)
+{
+	void *buf;
+	struct object *obj;
+	int eaten, i;
+	unsigned long size;
+	const unsigned char *tagged;
+
+	ref->value = xcalloc(sizeof(struct atom_value), used_atom_cnt);
+
+	buf = get_obj(ref->objectname, &obj, &size, &eaten);
+	if (!buf)
+		die("missing object %s for %s",
+		    sha1_to_hex(ref->objectname), ref->refname);
+	if (!obj)
+		die("parse_object_buffer failed on %s for %s",
+		    sha1_to_hex(ref->objectname), ref->refname);
+
+	/* Fill in specials first */
+	for (i = 0; i < used_atom_cnt; i++) {
+		const char *name = used_atom[i];
+		struct atom_value *v = &ref->value[i];
+		if (!strcmp(name, "refname"))
+			v->s = ref->refname;
+		else if (!strcmp(name, "*refname")) {
+			int len = strlen(ref->refname);
+			char *s = xmalloc(len + 4);
+			sprintf(s, "%s^{}", ref->refname);
+			v->s = s;
+		}
+	}
+
+	grab_values(ref->value, 0, obj, buf, size);
+	if (!eaten)
+		free(buf);
+
+	/* If there is no atom that wants to know about tagged
+	 * object, we are done.
+	 */
+	if (!need_tagged || (obj->type != OBJ_TAG))
+		return;
+
+	/* 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.
+	 */
+	tagged = ((struct tag *)obj)->tagged->sha1;
+
+	/* 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.
+	 */
+	buf = get_obj(tagged, &obj, &size, &eaten);
+	if (!buf)
+		die("missing object %s for %s",
+		    sha1_to_hex(tagged), ref->refname);
+	if (!obj)
+		die("parse_object_buffer failed on %s for %s",
+		    sha1_to_hex(tagged), ref->refname);
+	grab_values(ref->value, 1, obj, buf, size);
+	if (!eaten)
+		free(buf);
+}
+
+/*
+ * Given a ref, return the value for the atom.  This lazily gets value
+ * out of the object by calling populate value.
+ */
+static void get_value(struct refinfo *ref, int atom, struct atom_value **v)
+{
+	if (!ref->value) {
+		populate_value(ref);
+		fill_missing_values(ref->value);
+	}
+	*v = &ref->value[atom];
+}
+
+static struct refinfo **grab_array;
+static const char **grab_pattern;
+static int *grab_cnt;
+
+/*
+ * A call-back given to for_each_ref().  It is unfortunate that we
+ * need to use global variables to pass extra information to this
+ * function.
+ */
+static int grab_single_ref(const char *refname, const unsigned char *sha1)
+{
+	struct refinfo *ref;
+	int cnt;
+
+	if (*grab_pattern) {
+		const char **pattern;
+		int namelen = strlen(refname);
+		for (pattern = grab_pattern; *pattern; pattern++) {
+			const char *p = *pattern;
+			int plen = strlen(p);
+
+			if ((plen <= namelen) &&
+			    !strncmp(refname, p, plen) &&
+			    (refname[plen] == '\0' ||
+			     refname[plen] == '/'))
+				break;
+			if (!fnmatch(p, refname, FNM_PATHNAME))
+				break;
+		}
+		if (!*pattern)
+			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 = xcalloc(1, sizeof(*ref));
+	ref->refname = xstrdup(refname);
+	hashcpy(ref->objectname, sha1);
+
+	cnt = *grab_cnt;
+	grab_array = xrealloc(grab_array, sizeof(*grab_array) * (cnt + 1));
+	grab_array[cnt++] = ref;
+	*grab_cnt = cnt;
+	return 0;
+}
+
+static struct refinfo **grab_refs(const char **pattern, int *cnt)
+{
+	/* Sheesh, we really should make for-each-ref to take
+	 * callback data.
+	 */
+	*cnt = 0;
+	grab_pattern = pattern;
+	grab_cnt = cnt;
+	for_each_ref(grab_single_ref);
+	return grab_array;
+}
+
+static int cmp_ref_sort(struct ref_sort *s, struct refinfo *a, struct refinfo *b)
+{
+	struct atom_value *va, *vb;
+	int cmp;
+	cmp_type cmp_type = used_atom_type[s->atom];
+
+	get_value(a, s->atom, &va);
+	get_value(b, s->atom, &vb);
+	switch (cmp_type) {
+	case FIELD_STR:
+		cmp = strcmp(va->s, vb->s);
+		break;
+	default:
+		if (va->ul < vb->ul)
+			cmp = -1;
+		else if (va->ul == vb->ul)
+			cmp = 0;
+		else
+			cmp = 1;
+		break;
+	}
+	return (s->reverse) ? -cmp : cmp;
+}
+
+static struct ref_sort *ref_sort;
+static int compare_refs(const void *a_, const void *b_)
+{
+	struct refinfo *a = *((struct refinfo **)a_);
+	struct refinfo *b = *((struct refinfo **)b_);
+	struct ref_sort *s;
+
+	for (s = ref_sort; s; s = s->next) {
+		int cmp = cmp_ref_sort(s, a, b);
+		if (cmp)
+			return cmp;
+	}
+	return 0;
+}
+
+static void sort_refs(struct ref_sort *sort, struct refinfo **refs, int num_refs)
+{
+	ref_sort = sort;
+	qsort(refs, num_refs, sizeof(struct refinfo *), compare_refs);
+}
+
+static void print_value(struct refinfo *ref, int atom, int quote_style)
+{
+	struct atom_value *v;
+	get_value(ref, atom, &v);
+	switch (quote_style) {
+	case QUOTE_NONE:
+		fputs(v->s, stdout);
+		break;
+	case QUOTE_SHELL:
+		sq_quote_print(stdout, v->s);
+		break;
+	case QUOTE_PERL:
+		perl_quote_print(stdout, v->s);
+		break;
+	case QUOTE_PYTHON:
+		python_quote_print(stdout, v->s);
+		break;
+	}
+}
+
+static void emit(const char *cp, const char *ep)
+{
+	while (*cp && (!ep || cp < ep)) {
+		if (*cp == '%')
+			if (cp[1] == '%')
+				cp++;
+		putchar(*cp);
+		cp++;
+	}
+}
+
+static void show_ref(struct refinfo *info, const char *format, int quote_style)
+{
+	const char *cp, *sp, *ep;
+
+	for (cp = format; *cp && (sp = find_next(cp)); cp = ep + 1) {
+		ep = strchr(sp, ')');
+		if (cp < sp)
+			emit(cp, sp);
+		print_value(info, parse_atom(sp + 2, ep), quote_style);
+	}
+	if (*cp)
+		fputs(cp, stdout);
+	putchar('\n');
+}
+
+static struct ref_sort *default_sort(void)
+{
+	static const char cstr_name[] = "refname";
+
+	struct ref_sort *sort = xcalloc(1, sizeof(*sort));
+
+	sort->next = NULL;
+	sort->atom = parse_atom(cstr_name, cstr_name + strlen(cstr_name));
+	return sort;
+}
+
+int cmd_for_each_ref(int ac, const char **av, char *prefix)
+{
+	int i, num_refs;
+	const char *format = NULL;
+	struct ref_sort *sort = NULL, **sort_tail = &sort;
+	int maxcount = 0;
+	int quote_style = -1; /* unspecified yet */
+	struct refinfo **refs;
+
+	for (i = 1; i < ac; i++) {
+		const char *arg = av[i];
+		if (arg[0] != '-')
+			break;
+		if (!strcmp(arg, "--")) {
+			i++;
+			break;
+		}
+		if (!strncmp(arg, "--format=", 9)) {
+			if (format)
+				die("more than one --format?");
+			format = arg + 9;
+			continue;
+		}
+		if (!strcmp(arg, "-s") || !strcmp(arg, "--shell") ) {
+			if (0 <= quote_style)
+				die("more than one quoting style?");
+			quote_style = QUOTE_SHELL;
+			continue;
+		}
+		if (!strcmp(arg, "-p") || !strcmp(arg, "--perl") ) {
+			if (0 <= quote_style)
+				die("more than one quoting style?");
+			quote_style = QUOTE_PERL;
+			continue;
+		}
+		if (!strcmp(arg, "--python") ) {
+			if (0 <= quote_style)
+				die("more than one quoting style?");
+			quote_style = QUOTE_PYTHON;
+			continue;
+		}
+		if (!strncmp(arg, "--count=", 8)) {
+			if (maxcount)
+				die("more than one --count?");
+			maxcount = atoi(arg + 8);
+			if (maxcount <= 0)
+				die("The number %s did not parse", arg);
+			continue;
+		}
+		if (!strncmp(arg, "--sort=", 7)) {
+			struct ref_sort *s = xcalloc(1, sizeof(*s));
+			int len;
+
+			s->next = NULL;
+			*sort_tail = s;
+			sort_tail = &s->next;
+
+			arg += 7;
+			if (*arg == '-') {
+				s->reverse = 1;
+				arg++;
+			}
+			len = strlen(arg);
+			sort->atom = parse_atom(arg, arg+len);
+			continue;
+		}
+		break;
+	}
+	if (quote_style < 0)
+		quote_style = QUOTE_NONE;
+
+	if (!sort)
+		sort = default_sort();
+	sort_atom_limit = used_atom_cnt;
+	if (!format)
+		format = "%(objectname) %(objecttype)\t%(refname)";
+
+	verify_format(format);
+
+	refs = grab_refs(av + i, &num_refs);
+
+	for (i = 0; i < used_atom_cnt; i++) {
+		if (used_atom[i][0] == '*') {
+			need_tagged = 1;
+			break;
+		}
+	}
+
+	sort_refs(sort, refs, num_refs);
+
+	if (!maxcount || num_refs < maxcount)
+		maxcount = num_refs;
+	for (i = 0; i < maxcount; i++)
+		show_ref(refs[i], format, quote_style);
+	return 0;
+}
diff --git a/builtin.h b/builtin.h
index 25431d7..87d3326 100644
--- a/builtin.h
+++ b/builtin.h
@@ -26,6 +26,7 @@ extern int cmd_diff(int argc, const char
 extern int cmd_diff_stages(int argc, const char **argv, const char *prefix);
 extern int cmd_diff_tree(int argc, const char **argv, const char *prefix);
 extern int cmd_fmt_merge_msg(int argc, const char **argv, const char *prefix);
+extern int cmd_for_each_ref(int argc, const char **argv, const char *prefix);
 extern int cmd_format_patch(int argc, const char **argv, const char *prefix);
 extern int cmd_get_tar_commit_id(int argc, const char **argv, const char *prefix);
 extern int cmd_grep(int argc, const char **argv, const char *prefix);
@@ -47,8 +48,8 @@ extern int cmd_repo_config(int argc, con
 extern int cmd_rev_list(int argc, const char **argv, const char *prefix);
 extern int cmd_rev_parse(int argc, const char **argv, const char *prefix);
 extern int cmd_rm(int argc, const char **argv, const char *prefix);
-extern int cmd_show_branch(int argc, const char **argv, const char *prefix);
 extern int cmd_show(int argc, const char **argv, const char *prefix);
+extern int cmd_show_branch(int argc, const char **argv, const char *prefix);
 extern int cmd_stripspace(int argc, const char **argv, const char *prefix);
 extern int cmd_symbolic_ref(int argc, const char **argv, const char *prefix);
 extern int cmd_tar_tree(int argc, const char **argv, const char *prefix);
diff --git a/git.c b/git.c
index 8c182a5..10db27b 100644
--- a/git.c
+++ b/git.c
@@ -231,6 +231,7 @@ static void handle_internal_command(int 
 		{ "diff-stages", cmd_diff_stages, RUN_SETUP },
 		{ "diff-tree", cmd_diff_tree, RUN_SETUP },
 		{ "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
+		{ "for-each-ref", cmd_for_each_ref, RUN_SETUP },
 		{ "format-patch", cmd_format_patch, RUN_SETUP },
 		{ "get-tar-commit-id", cmd_get_tar_commit_id },
 		{ "grep", cmd_grep, RUN_SETUP },
diff --git a/object.c b/object.c
index 9281300..de244e2 100644
--- a/object.c
+++ b/object.c
@@ -138,42 +138,56 @@ struct object *lookup_unknown_object(con
 	return obj;
 }
 
+struct object *parse_object_buffer(const unsigned char *sha1, const char *type, unsigned long size, void *buffer, int *eaten_p)
+{
+	struct object *obj;
+	int eaten = 0;
+
+	if (!strcmp(type, blob_type)) {
+		struct blob *blob = lookup_blob(sha1);
+		parse_blob_buffer(blob, buffer, size);
+		obj = &blob->object;
+	} else if (!strcmp(type, tree_type)) {
+		struct tree *tree = lookup_tree(sha1);
+		obj = &tree->object;
+		if (!tree->object.parsed) {
+			parse_tree_buffer(tree, buffer, size);
+			eaten = 1;
+		}
+	} else if (!strcmp(type, commit_type)) {
+		struct commit *commit = lookup_commit(sha1);
+		parse_commit_buffer(commit, buffer, size);
+		if (!commit->buffer) {
+			commit->buffer = buffer;
+			eaten = 1;
+		}
+		obj = &commit->object;
+	} else if (!strcmp(type, tag_type)) {
+		struct tag *tag = lookup_tag(sha1);
+		parse_tag_buffer(tag, buffer, size);
+		obj = &tag->object;
+	} else {
+		obj = NULL;
+	}
+	*eaten_p = eaten;
+	return obj;
+}
+
 struct object *parse_object(const unsigned char *sha1)
 {
 	unsigned long size;
 	char type[20];
+	int eaten;
 	void *buffer = read_sha1_file(sha1, type, &size);
+
 	if (buffer) {
 		struct object *obj;
 		if (check_sha1_signature(sha1, buffer, size, type) < 0)
 			printf("sha1 mismatch %s\n", sha1_to_hex(sha1));
-		if (!strcmp(type, blob_type)) {
-			struct blob *blob = lookup_blob(sha1);
-			parse_blob_buffer(blob, buffer, size);
-			obj = &blob->object;
-		} else if (!strcmp(type, tree_type)) {
-			struct tree *tree = lookup_tree(sha1);
-			obj = &tree->object;
-			if (!tree->object.parsed) {
-				parse_tree_buffer(tree, buffer, size);
-				buffer = NULL;
-			}
-		} else if (!strcmp(type, commit_type)) {
-			struct commit *commit = lookup_commit(sha1);
-			parse_commit_buffer(commit, buffer, size);
-			if (!commit->buffer) {
-				commit->buffer = buffer;
-				buffer = NULL;
-			}
-			obj = &commit->object;
-		} else if (!strcmp(type, tag_type)) {
-			struct tag *tag = lookup_tag(sha1);
-			parse_tag_buffer(tag, buffer, size);
-			obj = &tag->object;
-		} else {
-			obj = NULL;
-		}
-		free(buffer);
+
+		obj = parse_object_buffer(sha1, type, size, buffer, &eaten);
+		if (!eaten)
+			free(buffer);
 		return obj;
 	}
 	return NULL;
diff --git a/object.h b/object.h
index 3d4ff46..caee733 100644
--- a/object.h
+++ b/object.h
@@ -59,6 +59,12 @@ void created_object(const unsigned char 
 /** Returns the object, having parsed it to find out what it is. **/
 struct object *parse_object(const unsigned char *sha1);
 
+/* Given the result of read_sha1_file(), returns the object after
+ * parsing it.  eaten_p indicates if the object has a borrowed copy
+ * of buffer and the caller should not free() it.
+ */
+struct object *parse_object_buffer(const unsigned char *sha1, const char *type, unsigned long size, void *buffer, int *eaten_p);
+
 /** Returns the object, with potentially excess memory allocated. **/
 struct object *lookup_unknown_object(const unsigned  char *sha1);
 
diff --git a/quote.c b/quote.c
index e3a4d4a..ee7d62c 100644
--- a/quote.c
+++ b/quote.c
@@ -349,3 +349,41 @@ void write_name_quoted(const char *prefi
 	else
 		goto no_quote;
 }
+
+/* quoting as a string literal for other languages */
+
+void perl_quote_print(FILE *stream, const char *src)
+{
+	const char sq = '\'';
+	const char bq = '\\';
+	char c;
+
+	fputc(sq, stream);
+	while ((c = *src++)) {
+		if (c == sq || c == bq)
+			fputc(bq, stream);
+		fputc(c, stream);
+	}
+	fputc(sq, stream);
+}
+
+void python_quote_print(FILE *stream, const char *src)
+{
+	const char sq = '\'';
+	const char bq = '\\';
+	const char nl = '\n';
+	char c;
+
+	fputc(sq, stream);
+	while ((c = *src++)) {
+		if (c == nl) {
+			fputc(bq, stream);
+			fputc('n', stream);
+			continue;
+		}
+		if (c == sq || c == bq)
+			fputc(bq, stream);
+		fputc(c, stream);
+	}
+	fputc(sq, stream);
+}
diff --git a/quote.h b/quote.h
index 1a29e79..b55e699 100644
--- a/quote.h
+++ b/quote.h
@@ -52,4 +52,8 @@ extern char *unquote_c_style(const char 
 extern void write_name_quoted(const char *prefix, int prefix_len,
 			      const char *name, int quote, FILE *out);
 
+/* quoting as a string literal for other languages */
+extern void perl_quote_print(FILE *stream, const char *src);
+extern void python_quote_print(FILE *stream, const char *src);
+
 #endif
-- 
1.4.2.1.gcd6f1

Re: Add "git show-ref" builtin command

[Jakub Narebski]

Junio C Hamano wrote:

> +<format>::
> +       A string that interpolates `%(fieldname)` from the
> +       object pointed at by a ref being shown.  If `fieldname`
> +       is prefixed with an asterisk (`*`) and the ref points
> +       at a tag object, the value for the field in the object
> +       tag refers is used.  When unspecified, defaults to
> +       `%(refname)`.

Wouldn't it be better to be able to use (or be able to enable, like echo -e
option) interpretation of the  backslash-escaped characters, like 
\t, \n, \0?

-- 
Jakub Narebski
Warsaw, Poland
ShadeHawk on #git

Teach "git checkout" to use git-show-ref

[Linus Torvalds]

That way, it doesn't care how the refs are stored any more

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

Just as an example of how to use git-show-ref rather than knowing about 
"$GIT_DIR/refs/..." paths.

This basically replaces my much hackier version that is in the "lt/refs" 
branch, but can go into the master branch independently of the 
refs-packing work.

diff --git a/git-checkout.sh b/git-checkout.sh
index 580a9e8..6e4c535 100755
--- a/git-checkout.sh
+++ b/git-checkout.sh
@@ -22,7 +22,7 @@ while [ "$#" != "0" ]; do
 		shift
 		[ -z "$newbranch" ] &&
 			die "git checkout: -b needs a branch name"
-		[ -e "$GIT_DIR/refs/heads/$newbranch" ] &&
+		git-show-ref --verify --quiet -- "refs/heads/$newbranch" &&
 			die "git checkout: branch $newbranch already exists"
 		git-check-ref-format "heads/$newbranch" ||
 			die "git checkout: we do not like '$newbranch' as a branch name."
@@ -51,7 +51,7 @@ while [ "$#" != "0" ]; do
 			fi
 			new="$rev"
 			new_name="$arg^0"
-			if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
+			if git-show-ref --verify --quiet -- "refs/heads/$arg" ]; then
 				branch="$arg"
 			fi
 		elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)

Re: Teach "git checkout" to use git-show-ref

[Jakub Narebski]

Linus Torvalds wrote:

> @@ -51,7 +51,7 @@ while [ "$#" != "0" ]; do
>                         fi
>                         new="$rev"
>                         new_name="$arg^0"
> -                       if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
> +                       if git-show-ref --verify --quiet -- "refs/heads/$arg" ]; then
  +                       if git-show-ref --verify --quiet -- "refs/heads/$arg"; then
>                                 branch="$arg"
>                         fi
>                 elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)

There is leftover ] before ; in if.

-- 
Jakub Narebski
Warsaw, Poland
ShadeHawk on #git

Re: Add "git show-ref" builtin command

[Junio C Hamano]

Jakub Narebski <jnareb@gmail.com> writes:

> Wouldn't it be better to be able to use (or be able to enable, like echo -e
> option) interpretation of the  backslash-escaped characters, like 
> \t, \n, \0?

I've been thinking about letting the --format to specify
embedding arbitrary byte value in the output.

This option however is mostly to help Porcelain written in
languages other than C (and that is where the language specific
quoting styles come in) to allow a template of a scriptlet to be
specified, as you have probably seen in the examples in the
documentation page, so I think it is more user friendly to leave
backslash as just a literal character.

My current thinking is to allow you to say %XX (a per-cent
followed by exactly two hexadecimal digits) to do embed a
literal byte value.  Then a Porcelain written in Perl that does
not want to eval output can do something like this:

	my $fmt = 'r%(refname)%00o%(objectname)%00%00';
	open R, '-|', 'git-for-each-ref', "--format=$fmt";
	my $all = join('', <R>);
	close R;        	        
        for (split(/\0\0/, $all)) {
		/r(.*?)\0o(.*)/ &&
                print "ref = $1, obj = $2\n";
        }

Another thing is that originally I picked %(name) syntax because
I thought we might want to do fancier "%20(column)d" like Python
does with its string formatting operator.  But I now think it
makes more sense to output whatever is asked as string literals
and have host language worry about formatting.  So in that
sense, using %() as our formatting specifier will get in the way
for people who writes in Python.  Maybe I should change it to
something like %{name} instead (not ${name} -- that would
interfere with the shell and Perl).

Anyhow, on top of the previous one, this will let you say %00 to
embed a NUL in your string.

diff --git a/builtin-for-each-ref.c b/builtin-for-each-ref.c
index f064e7e..698618b 100644
--- a/builtin-for-each-ref.c
+++ b/builtin-for-each-ref.c
@@ -710,12 +710,39 @@ static void print_value(struct refinfo *
 	}
 }
 
+static int hex1(char ch)
+{
+	if ('0' <= ch && ch <= '9')
+		return ch - '0';
+	else if ('a' <= ch && ch <= 'f')
+		return ch - 'a' + 10;
+	else if ('A' <= ch && ch <= 'F')
+		return ch - 'A' + 10;
+	return -1;
+}
+static int hex2(const char *cp)
+{
+	if (cp[0] && cp[1])
+		return (hex1(cp[0]) << 4) | hex1(cp[1]);
+	else
+		return -1;
+}
+
 static void emit(const char *cp, const char *ep)
 {
 	while (*cp && (!ep || cp < ep)) {
-		if (*cp == '%')
+		if (*cp == '%') {
 			if (cp[1] == '%')
 				cp++;
+			else {
+				int ch = hex2(cp + 1);
+				if (0 <= ch) {
+					putchar(ch);
+					cp += 3;
+					continue;
+				}
+			}
+		}
 		putchar(*cp);
 		cp++;
 	}
@@ -731,8 +758,10 @@ static void show_ref(struct refinfo *inf
 			emit(cp, sp);
 		print_value(info, parse_atom(sp + 2, ep), quote_style);
 	}
-	if (*cp)
-		fputs(cp, stdout);
+	if (*cp) {
+		sp = cp + strlen(cp);
+		emit(cp, sp);
+	}
 	putchar('\n');
 }
 

Re: Teach "git checkout" to use git-show-ref

[Junio C Hamano]

Linus Torvalds <torvalds@osdl.org> writes:

> That way, it doesn't care how the refs are stored any more
>
> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
> ---
>
> Just as an example of how to use git-show-ref rather than knowing about 
> "$GIT_DIR/refs/..." paths.
>
> This basically replaces my much hackier version that is in the "lt/refs" 
> branch, but can go into the master branch independently of the 
> refs-packing work.

I kind of liked the rev-parse one better for this particular
command, but only slightly (by using --verify on "$arg^0", you
were also making sure what's in refs/heads/ was a commit object,
but that check is gone with this patch.  It is not a loss,
because the original code did not check it, and nobody should be
placing anything but commits under refs/heads anyway).

> diff --git a/git-checkout.sh b/git-checkout.sh
> index 580a9e8..6e4c535 100755
> --- a/git-checkout.sh
> +++ b/git-checkout.sh
>...
> @@ -51,7 +51,7 @@ while [ "$#" != "0" ]; do
>  			fi
>  			new="$rev"
>  			new_name="$arg^0"
> -			if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
> +			if git-show-ref --verify --quiet -- "refs/heads/$arg" ]; then
>  				branch="$arg"
>  			fi
>  		elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)