Merge branch 'cc/replace'

* cc/replace:
  t6050: check pushing something based on a replaced commit
  Documentation: add documentation for "git replace"
  Add git-replace to .gitignore
  builtin-replace: use "usage_msg_opt" to give better error messages
  parse-options: add new function "usage_msg_opt"
  builtin-replace: teach "git replace" to actually replace
  Add new "git replace" command
  environment: add global variable to disable replacement
  mktag: call "check_sha1_signature" with the replacement sha1
  replace_object: add a test case
  object: call "check_sha1_signature" with the replacement sha1
  sha1_file: add a "read_sha1_file_repl" function
  replace_object: add mechanism to replace objects found in "refs/replace/"
  refs: add a "for_each_replace_ref" function

1 files changed, 18 insertions, 5 deletions

diff --git a/sha1_file.c b/sha1_file.c
index 1d996a1990..4ea0b18d0a 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -2144,13 +2144,26 @@ static void *read_object(const unsigned char *sha1, enum object_type *type,
 	return read_packed_sha1(sha1, type, size);
 }
 
-void *read_sha1_file(const unsigned char *sha1, enum object_type *type,
-		     unsigned long *size)
+void *read_sha1_file_repl(const unsigned char *sha1,
+			  enum object_type *type,
+			  unsigned long *size,
+			  const unsigned char **replacement)
 {
-	void *data = read_object(sha1, type, size);
+	const unsigned char *repl = lookup_replace_object(sha1);
+	void *data = read_object(repl, type, size);
+
+	/* die if we replaced an object with one that does not exist */
+	if (!data && repl != sha1)
+		die("replacement %s not found for %s",
+		    sha1_to_hex(repl), sha1_to_hex(sha1));
+
 	/* legacy behavior is to die on corrupted objects */
-	if (!data && (has_loose_object(sha1) || has_packed_and_bad(sha1)))
-		die("object %s is corrupted", sha1_to_hex(sha1));
+	if (!data && (has_loose_object(repl) || has_packed_and_bad(repl)))
+		die("object %s is corrupted", sha1_to_hex(repl));
+
+	if (replacement)
+		*replacement = repl;
+
 	return data;
 }