[PATCH] Extend cat-file to take multiple arguments or read input from stdin.

[Han-Wen Nienhuys <hanwen@xs4all.nl>]

With this patch, cat-file can be invoked either on an arbitrary number
of objects, eg.

  git cat-file commit HEAD HEAD^^^

the object names can also be supplied on stdin, like so

  echo  -e 'HEAD\nHEAD^^^' | git cat-file commit -

With this functionality, the entire object database can be dumped with
a limited number of processes: two cat-file processes for discovering size and
type, and one cat-file process per type.

Signed-off-by: Han-Wen Nienhuys <hanwen@xs4all.nl>
---
 builtin-cat-file.c |   63 ++++++++++++++++++++++++++++++++++++++--------------
 1 files changed, 46 insertions(+), 17 deletions(-)

diff --git a/builtin-cat-file.c b/builtin-cat-file.c
index f132d58..57e2111 100644
--- a/builtin-cat-file.c
+++ b/builtin-cat-file.c
@@ -76,31 +76,17 @@ static void pprint_tag(const unsigned char *sha1, const char *buf, unsigned long
 		write_or_die(1, cp, endp - cp);
 }
 
-int cmd_cat_file(int argc, const char **argv, const char *prefix)
+
+int cat_one_file (const char *obj_name, int opt, const char *exp_type)
 {
 	unsigned char sha1[20];
-	enum object_type type;
 	void *buf;
 	unsigned long size;
-	int opt;
-	const char *exp_type, *obj_name;
-
-	git_config(git_default_config);
-	if (argc != 3)
-		usage("git-cat-file [-t|-s|-e|-p|<type>] <sha1>");
-	exp_type = argv[1];
-	obj_name = argv[2];
+	enum object_type type;
 
 	if (get_sha1(obj_name, sha1))
 		die("Not a valid object name %s", obj_name);
 
-	opt = 0;
-	if ( exp_type[0] == '-' ) {
-		opt = exp_type[1];
-		if ( !opt || exp_type[2] )
-			opt = -1; /* Not a single character option */
-	}
-
 	buf = NULL;
 	switch (opt) {
 	case 't':
@@ -157,3 +143,46 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
 	write_or_die(1, buf, size);
 	return 0;
 }
+
+int cmd_cat_file(int argc, const char **argv, const char *prefix)
+{
+	int opt = 0;
+	const char *exp_type;
+	int all_exists = 1;
+	struct strbuf buf;
+
+	git_config(git_default_config);
+	if (argc < 3)
+		usage("git-cat-file [-t|-s|-e|-p|<type>] <sha1> ... ");
+	exp_type = argv[1];
+
+	if ( exp_type[0] == '-' ) {
+		opt = exp_type[1];
+		if ( !opt || exp_type[2] )
+			opt = -1; /* Not a single character option */
+	}
+
+	argv += 2;
+	strbuf_init(&buf, 0);
+	do {
+		const char *arg = NULL;
+		if (argv[0] == NULL)
+			break;
+		if (strcmp(argv[0], "-")) {
+			arg = *argv;
+			argv++;
+		} else {
+			if (strbuf_getline(&buf, stdin, '\n') == EOF)
+				break;
+			arg = buf.buf;
+		}
+		int not_exists_one = cat_one_file(arg, opt, exp_type);
+		if (opt == 'e')
+			all_exists = all_exists && !not_exists_one;
+		if (not_exists_one)
+			break;
+	} while (1);
+	strbuf_release(&buf);
+	return !all_exists;
+}
+
-- 
1.5.3.4


-- 
 Han-Wen Nienhuys - hanwen@xs4all.nl - http://www.xs4all.nl/~hanwen