correct ce_compare_data() in a middle of a mergetb/convert-peek-in-index

The following didn't work as expected:

 - In a middle of a merge
 - merge.renormalize is true,
 - .gitattributes = "* text=auto"
 - core.eol = crlf

Merge a blob with CRLF "first line\r\nsame line\r\n" and a blob
with LF "first line\nsame line\n".

The expected result of the merge is "first line\nsame line\n".

The content in the working tree is "first line\r\nsame line\r\n",
and ce_compare_data() should find that the content is clean and return 0.

Deep down crlf_to_git() is invoked, to check if CRLF are converted or not.

The "new safer autocrlf handling" calls blob_has_cr().

Instead of using the sha1 of the blob, (CRLF in this example),
the function get_sha1_from_index() is invoked.
get_sha1_from_index() decides to return "ours" when in the middle of
the merge, which is LF.

As a result, the CRLF in the worktree are converted into LF before
the comparison.
The contents of LF and CRLF don't match any more.

The problem is that ce_compare_data() has ce->sha1, but the sha1 is lost
on it's way into blob_has_cr().

Forwarding ce->sha1 from ce_compare_data() into crlf_to_git() makes sure
that blob_has_cr() looks at the appropriate blob.

Add a new parameter index_blob_sha1 to convert_to_git(), and forward the
sha1 from ce_compare_data() into convert_to_git(). Other callers use NULL
for index_blob_sha1, and the sha1 is determined from path
using get_sha1_from_cache(path). This is the same handling as before.

In the same spirit, forward the sha1 into would_convert_to_git().

While at it, rename has_cr_in_index() into blob_has_cr()
and replace 0 with SAFE_CRLF_FALSE.

Add a TC in t6038 to have a test coverage under Linux.

Signed-off-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 11 insertions, 4 deletions

diff --git a/convert.h b/convert.h
index 82871a11d5..97d427296f 100644
--- a/convert.h
+++ b/convert.h
@@ -39,19 +39,26 @@ extern const char *get_convert_attr_ascii(const char *path);
 
 /* returns 1 if *dst was used */
 extern int convert_to_git(const char *path, const char *src, size_t len,
-			  struct strbuf *dst, enum safe_crlf checksafe);
+			  struct strbuf *dst, enum safe_crlf checksafe,
+			  const unsigned char *index_blob_sha1);
+
 extern int convert_to_working_tree(const char *path, const char *src,
 				   size_t len, struct strbuf *dst);
 extern int renormalize_buffer(const char *path, const char *src, size_t len,
 			      struct strbuf *dst);
-static inline int would_convert_to_git(const char *path)
+static inline int would_convert_to_git(const char *path,
+				       const unsigned char *index_blob_sha1)
 {
-	return convert_to_git(path, NULL, 0, NULL, 0);
+	return convert_to_git(path, NULL, 0, NULL, SAFE_CRLF_FALSE,
+			      index_blob_sha1);
 }
+
 /* Precondition: would_convert_to_git_filter_fd(path) == true */
 extern void convert_to_git_filter_fd(const char *path, int fd,
 				     struct strbuf *dst,
-				     enum safe_crlf checksafe);
+				     enum safe_crlf checksafe,
+				     const unsigned char *index_blob_sha1);
+
 extern int would_convert_to_git_filter_fd(const char *path);
 
 /*****************************************************************