show: honor --textconv for blobs

Currently, "diff" and "cat-file" for blobs honor "--textconv" options
(with the former defaulting to "--textconv" and the latter to
"--no-textconv") whereas "show" does not honor this option, even though
it takes diff options.

Make "show" on blobs honor "--textconv" when it is asked.  The default
is not to apply textconv, which is in line with what "cat-file" does.

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/log.c

@@ -406,10 +406,29 @@ static void show_tagger(char *buf, int len, struct rev_info *rev)
 	strbuf_release(&out);
 }
 
-static int show_blob_object(const unsigned char *sha1, struct rev_info *rev)
+static int show_blob_object(const unsigned char *sha1, struct rev_info *rev, const char *obj_name)
 {
+	unsigned char sha1c[20];
+	struct object_context obj_context;
+	char *buf;
+	unsigned long size;
+
 	fflush(stdout);
-	return stream_blob_to_fd(1, sha1, NULL, 0);
+	if (!DIFF_OPT_TOUCHED(&rev->diffopt, ALLOW_TEXTCONV) ||
+	    !DIFF_OPT_TST(&rev->diffopt, ALLOW_TEXTCONV))
+		return stream_blob_to_fd(1, sha1, NULL, 0);
+
+	if (get_sha1_with_context(obj_name, 0, sha1c, &obj_context))
+		die("Not a valid object name %s", obj_name);
+	if (!obj_context.path[0] ||
+	    !textconv_object(obj_context.path, obj_context.mode, sha1c, 1, &buf, &size))
+		return stream_blob_to_fd(1, sha1, NULL, 0);
+
+	if (!buf)
+		die("git show %s: bad file", obj_name);
+
+	write_or_die(1, buf, size);
+	return 0;
 }
 
 static int show_tag_object(const unsigned char *sha1, struct rev_info *rev)
@@ -495,7 +514,7 @@ int cmd_show(int argc, const char **argv, const char *prefix)
 		const char *name = objects[i].name;
 		switch (o->type) {
 		case OBJ_BLOB:
-			ret = show_blob_object(o->sha1, NULL);
+			ret = show_blob_object(o->sha1, &rev, name);
 			break;
 		case OBJ_TAG: {
 			struct tag *t = (struct tag *)o;

t/t4030-diff-textconv.sh

@@ -96,14 +96,14 @@ test_expect_success 'show blob produces binary' '
 	test_cmp expect actual
 '
 
-test_expect_failure 'show --textconv blob produces text' '
+test_expect_success 'show --textconv blob produces text' '
 	git show --textconv HEAD:file >actual &&
 	printf "0\\n1\\n" >expect &&
 	test_cmp expect actual
 '
 
-test_success 'show --no-textconv blob produces binary' '
-	git show --textconv HEAD:file >actual &&
+test_expect_success 'show --no-textconv blob produces binary' '
+	git show --no-textconv HEAD:file >actual &&
 	printf "\\0\\n\\01\\n" >expect &&
 	test_cmp expect actual
 '