[PATCH v3 1/2] cat-file: add mailmap support to -s option

[Siddharth Asthana <siddharthasthana31@gmail.com>]

Even though the cat-file command with `-s` option does not complain when
`--use-mailmap` option is given, the latter option is ignored. Compute
the size of the object after replacing the idents and report it instead.

In order to make `-s` option honour the mailmap mechanism we have to
read the contents of the commit/tag object. Make use of the call to
`oid_object_info_extended()` to get the contents of the object and store
in `buf`. `buf` is later freed in the function.

Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: John Cai <johncai86@gmail.com>
Signed-off-by: Siddharth Asthana <siddharthasthana31@gmail.com>
---
 Documentation/git-cat-file.txt |  4 +++-
 builtin/cat-file.c             | 13 +++++++++++++
 t/t4203-mailmap.sh             | 29 +++++++++++++++++++++++++++++
 3 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/Documentation/git-cat-file.txt b/Documentation/git-cat-file.txt
index ec30b5c574..594b6f2dfd 100644
--- a/Documentation/git-cat-file.txt
+++ b/Documentation/git-cat-file.txt
@@ -45,7 +45,9 @@ OPTIONS
 
 -s::
 	Instead of the content, show the object size identified by
-	`<object>`.
+	`<object>`. If used with `--use-mailmap` option, will show the
+	size of updated object after replacing idents using the mailmap
+	mechanism.
 
 -e::
 	Exit with zero status if `<object>` exists and is a valid
diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index fa7bd89169..8a6e2343ec 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -132,8 +132,21 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 
 	case 's':
 		oi.sizep = &size;
+
+		if (use_mailmap) {
+			oi.typep = &type;
+			oi.contentp = (void**)&buf;
+		}
+
 		if (oid_object_info_extended(the_repository, &oid, &oi, flags) < 0)
 			die("git cat-file: could not get object info");
+
+		if (use_mailmap && (type == OBJ_COMMIT || type == OBJ_TAG)) {
+			size_t s = size;
+			buf = replace_idents_using_mailmap(buf, &s);
+			size = cast_size_t_to_ulong(s);
+		}
+
 		printf("%"PRIuMAX"\n", (uintmax_t)size);
 		ret = 0;
 		goto cleanup;
diff --git a/t/t4203-mailmap.sh b/t/t4203-mailmap.sh
index cd1cab3e54..b500b31c92 100755
--- a/t/t4203-mailmap.sh
+++ b/t/t4203-mailmap.sh
@@ -1022,4 +1022,33 @@ test_expect_success '--mailmap enables mailmap in cat-file for annotated tag obj
 	test_cmp expect actual
 '
 
+test_expect_success 'git cat-file -s returns correct size with --use-mailmap' '
+	test_when_finished "rm .mailmap" &&
+	cat >.mailmap <<-\EOF &&
+	C O Mitter <committer@example.com> Orig <orig@example.com>
+	EOF
+	cat >expect <<-\EOF &&
+	209
+	220
+	EOF
+	git cat-file -s HEAD >actual &&
+	git cat-file --use-mailmap -s HEAD >>actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'git cat-file -s returns correct size with --use-mailmap for tag objects' '
+	test_when_finished "rm .mailmap" &&
+	cat >.mailmap <<-\EOF &&
+	Orig <orig@example.com> C O Mitter <committer@example.com>
+	EOF
+	git tag -a -m "annotated tag" v3 &&
+	cat >expect <<-\EOF &&
+	141
+	130
+	EOF
+	git cat-file -s v3 >actual &&
+	git cat-file --use-mailmap -s v3 >>actual &&
+	test_cmp expect actual
+'
+
 test_done
-- 
2.38.1.282.g2e87897fbb