Re: Bug: problem with file named with dash character

[Junio C Hamano <gitster@pobox.com>]

Junio C Hamano <gitster@pobox.com> writes:

> Junio C Hamano <gitster@pobox.com> writes:
>
>> Junio C Hamano <gitster@pobox.com> writes:
>>
>>> Jeff King <peff@peff.net> writes:
>>>
>>>> but that code path should be fixed properly (with a use_stdin flag in
>>>> the filespec).
>>>
>>> Yes, just as I said; I am finding more and more issues with the
>>> no-index hack that I have been fixing a bit by bit since I send the
>>> message you responded to.
>>
>> It is not ready yet, but here are a few patches WIP.
>
> And this is the second clean-up

And this is the third one.

-- >8 --
Subject: [PATCH 3/?] 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>
---
 diff-no-index.c | 33 +++++++++++++++++++++++++++++++--
 diff.c          | 21 +--------------------
 diffcore.h      |  1 +
 3 files changed, 33 insertions(+), 22 deletions(-)

diff --git a/diff-no-index.c b/diff-no-index.c
index a5c1e3e..9385d53 100644
--- a/diff-no-index.c
+++ b/diff-no-index.c
@@ -32,6 +32,12 @@ static int read_directory(const char *path, struct string_list *list)
 	return 0;
 }
 
+/*
+ * This should be "(standard input)", but it will probably expose many
+ * more breakages.
+ */
+static const char file_from_standard_input[] = "-";
+
 static int get_mode(const char *path, int *mode)
 {
 	struct stat st;
@@ -42,7 +48,7 @@ static int get_mode(const char *path, int *mode)
 	else if (!strcasecmp(path, "nul"))
 		*mode = 0;
 #endif
-	else if (!strcmp(path, "-"))
+	else if (path == file_from_standard_input)
 		*mode = create_ce_mode(0666);
 	else if (lstat(path, &st))
 		return error("Could not access '%s'", path);
@@ -51,6 +57,23 @@ static int get_mode(const char *path, int *mode)
 	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;
+	s->nongit_stdin = 1;
+	return 0;
+}
+
 static int queue_diff(struct diff_options *o,
 		      const char *name1, const char *name2)
 {
@@ -143,8 +166,14 @@ static int queue_diff(struct diff_options *o,
 			name2 = "/dev/null";
 		d1 = alloc_filespec(name1);
 		d2 = alloc_filespec(name2);
+
 		fill_filespec(d1, null_sha1, mode1);
+		if (name1 == file_from_standard_input)
+			populate_from_stdin(d1);
+
 		fill_filespec(d2, null_sha1, mode2);
+		if (name2 == file_from_standard_input)
+			populate_from_stdin(d2);
 
 		diff_queue(&diff_queued_diff, d1, d2);
 		return 0;
@@ -240,7 +269,7 @@ void diff_no_index(struct rev_info *revs,
 			 * stdin should be spelled as "-"; if you have
 			 * path that is "-", spell it as "./-".
 			 */
-			p = p;
+			p = file_from_standard_input;
 		else if (prefixlen)
 			p = xstrdup(prefix_filename(prefix, prefixlen, p));
 		paths[i] = p;
diff --git a/diff.c b/diff.c
index 1a594df..0c73c84 100644
--- a/diff.c
+++ b/diff.c
@@ -2619,22 +2619,6 @@ 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;
@@ -2684,9 +2668,6 @@ 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:
@@ -3048,7 +3029,7 @@ 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->nongit_stdin) {
 				hashcpy(one->sha1, null_sha1);
 				return;
 			}
diff --git a/diffcore.h b/diffcore.h
index 8f32b82..ef4fe17 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -42,6 +42,7 @@ struct diff_filespec {
 #define DIFF_FILE_VALID(spec) (((spec)->mode) != 0)
 	unsigned should_free : 1; /* data should be free()'ed */
 	unsigned should_munmap : 1; /* data should be munmap()'ed */
+	unsigned nongit_stdin : 1; /* data is from a nongit source */
 	unsigned dirty_submodule : 2;  /* For submodules: its work tree is dirty */
 #define DIRTY_SUBMODULE_UNTRACKED 1
 #define DIRTY_SUBMODULE_MODIFIED  2
-- 
1.7.11.1.184.g3ee8f69