diff-index.c: "git diff" has no need to read blob from the standard input

Only "diff --no-index -" does.  Bolting the logic into the low-level
function diff_populate_filespec() was a layering violation from day
one.  Move populate_from_stdin() function out of the generic diff.c
to its only user, diff-index.c.

Also make sure "-" from the command line stays a special token "read
from the standard input", even if we later decide to sanitize the
result from prefix_filename() function in a few obvious ways,
e.g. removing unnecessary "./" prefix, duplicated slashes "//" in
the middle, etc.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 20 deletions

diff --git a/diff.c b/diff.c
index 9038f190ec..d6fdb8e31f 100644
--- a/diff.c
+++ b/diff.c
@@ -2426,22 +2426,6 @@ static int reuse_worktree_file(const char *name, const unsigned char *sha1, int
 	return 0;
 }
 
-static int populate_from_stdin(struct diff_filespec *s)
-{
-	struct strbuf buf = STRBUF_INIT;
-	size_t size = 0;
-
-	if (strbuf_read(&buf, 0, 0) < 0)
-		return error("error while reading from stdin %s",
-				     strerror(errno));
-
-	s->should_munmap = 0;
-	s->data = strbuf_detach(&buf, &size);
-	s->size = size;
-	s->should_free = 1;
-	return 0;
-}
-
 static int diff_populate_gitlink(struct diff_filespec *s, int size_only)
 {
 	int len;
@@ -2491,9 +2475,6 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only)
 		struct stat st;
 		int fd;
 
-		if (!strcmp(s->path, "-"))
-			return populate_from_stdin(s);
-
 		if (lstat(s->path, &st) < 0) {
 			if (errno == ENOENT) {
 			err_empty:
@@ -2855,7 +2836,7 @@ static void diff_fill_sha1_info(struct diff_filespec *one)
 	if (DIFF_FILE_VALID(one)) {
 		if (!one->sha1_valid) {
 			struct stat st;
-			if (!strcmp(one->path, "-")) {
+			if (one->is_stdin) {
 				hashcpy(one->sha1, null_sha1);
 				return;
 			}