[PATCH v5 0/7] Check replacement object type and minor updates

[PATCH v5 0/7] Check replacement object type and minor updates

[Christian Couder]

Many patchs have been squashed together as Junio suggested.
And in patch 3/7 now no grep is done on the error message.

Christian Couder (7):
  replace: forbid replacing an object with one of a different type
  Documentation/replace: state that objects must be of the same type
  t6050-replace: test that objects are of the same type
  t6050-replace: add test to clean up all the replace refs
  Documentation/replace: add Creating Replacement Objects section
  replace: allow long option names
  t6050-replace: use some long option names

 Documentation/git-replace.txt | 28 +++++++++++++++++++++++++---
 builtin/replace.c             | 16 +++++++++++++---
 t/t6050-replace.sh            | 25 ++++++++++++++++++++++---
 3 files changed, 60 insertions(+), 9 deletions(-)

-- 
1.8.4.rc1.28.ge2684af

[PATCH v5 1/7] replace: forbid replacing an object with one of a different type

[Christian Couder]

Users replacing an object with one of a different type were not
prevented to do so, even if it was obvious, and stated in the doc,
that bad things would result from doing that.

To avoid mistakes, it is better to just forbid that though.

If -f option, which means '--force', is used, we can allow an object
to be replaced with one of a different type, as the user should know
what (s)he is doing.

If one object is replaced with one of a different type, the only way
to keep the history valid is to also replace all the other objects
that point to the replaced object. That's because:

* Annotated tags contain the type of the tagged object.

* The tree/parent lines in commits must be a tree and commits, resp.

* The object types referred to by trees are specified in the 'mode'
  field:
    100644 and 100755    blob
    160000               commit
    040000               tree
  (these are the only valid modes)

* Blobs don't point at anything.

The doc will be updated in a later patch.

Acked-by: Philip Oakley <philipoakley@iee.org>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 builtin/replace.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/builtin/replace.c b/builtin/replace.c
index 59d3115..95736d9 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -85,6 +85,7 @@ static int replace_object(const char *object_ref, const char *replace_ref,
 			  int force)
 {
 	unsigned char object[20], prev[20], repl[20];
+	enum object_type obj_type, repl_type;
 	char ref[PATH_MAX];
 	struct ref_lock *lock;
 
@@ -100,6 +101,15 @@ static int replace_object(const char *object_ref, const char *replace_ref,
 	if (check_refname_format(ref, 0))
 		die("'%s' is not a valid ref name.", ref);
 
+	obj_type = sha1_object_info(object, NULL);
+	repl_type = sha1_object_info(repl, NULL);
+	if (!force && obj_type != repl_type)
+		die("Objects must be of the same type.\n"
+		    "'%s' points to a replaced object of type '%s'\n"
+		    "while '%s' points to a replacement object of type '%s'.",
+		    object_ref, typename(obj_type),
+		    replace_ref, typename(repl_type));
+
 	if (read_ref(ref, prev))
 		hashclr(prev);
 	else if (!force)
-- 
1.8.4.rc1.28.ge2684af

[PATCH v5 2/7] Documentation/replace: state that objects must be of the same type

[Christian Couder]

A previous patch ensures that both the replaced and the replacement
objects passed to git replace must be of the same type, except if
-f option is used.

While at it state that there is no other restriction on both objects.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 Documentation/git-replace.txt | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-replace.txt b/Documentation/git-replace.txt
index e0b4057..d198006 100644
--- a/Documentation/git-replace.txt
+++ b/Documentation/git-replace.txt
@@ -20,8 +20,13 @@ The name of the 'replace' reference is the SHA-1 of the object that is
 replaced. The content of the 'replace' reference is the SHA-1 of the
 replacement object.
 
+The replaced object and the replacement object must be of the same type.
+This restriction can be bypassed using `-f`.
+
 Unless `-f` is given, the 'replace' reference must not yet exist.
 
+There is no other restriction on the replaced and replacement objects.
+
 Replacement references will be used by default by all Git commands
 except those doing reachability traversal (prune, pack transfer and
 fsck).
@@ -69,9 +74,7 @@ go back to a replaced commit will move the branch to the replacement
 commit instead of the replaced commit.
 
 There may be other problems when using 'git rev-list' related to
-pending objects. And of course things may break if an object of one
-type is replaced by an object of another type (for example a blob
-replaced by a commit).
+pending objects.
 
 SEE ALSO
 --------
-- 
1.8.4.rc1.28.ge2684af

[PATCH v5 3/7] t6050-replace: test that objects are of the same type

[Christian Couder]

and that the -f option bypasses the type check

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 t/t6050-replace.sh | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/t/t6050-replace.sh b/t/t6050-replace.sh
index decdc33..09bad98 100755
--- a/t/t6050-replace.sh
+++ b/t/t6050-replace.sh
@@ -263,4 +263,17 @@ test_expect_success 'not just commits' '
 	test_cmp file.replaced file
 '
 
+test_expect_success 'replaced and replacement objects must be of the same type' '
+	test_must_fail git replace mytag $HASH1 &&
+	test_must_fail git replace HEAD^{tree} HEAD~1 &&
+	BLOB=$(git rev-parse :file) &&
+	test_must_fail git replace HEAD^ $BLOB
+'
+
+test_expect_success '-f option bypasses the type check' '
+	git replace -f mytag $HASH1 &&
+	git replace -f HEAD^{tree} HEAD~1 &&
+	git replace -f HEAD^ $BLOB
+'
+
 test_done
-- 
1.8.4.rc1.28.ge2684af

[PATCH v5 4/7] t6050-replace: add test to clean up all the replace refs

[Christian Couder]

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 t/t6050-replace.sh | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/t/t6050-replace.sh b/t/t6050-replace.sh
index 09bad98..09a2b49 100755
--- a/t/t6050-replace.sh
+++ b/t/t6050-replace.sh
@@ -276,4 +276,10 @@ test_expect_success '-f option bypasses the type check' '
 	git replace -f HEAD^ $BLOB
 '
 
+test_expect_success 'replace ref cleanup' '
+	test -n "$(git replace)" &&
+	git replace -d $(git replace) &&
+	test -z "$(git replace)"
+'
+
 test_done
-- 
1.8.4.rc1.28.ge2684af

[PATCH v5 5/7] Documentation/replace: add Creating Replacement Objects section

[Christian Couder]

There were no hints in the documentation about how to create
replacement objects.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 Documentation/git-replace.txt | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/Documentation/git-replace.txt b/Documentation/git-replace.txt
index d198006..a2bd2ee 100644
--- a/Documentation/git-replace.txt
+++ b/Documentation/git-replace.txt
@@ -66,6 +66,19 @@ OPTIONS
 	Typing "git replace" without arguments, also lists all replace
 	refs.
 
+CREATING REPLACEMENT OBJECTS
+----------------------------
+
+linkgit:git-filter-branch[1], linkgit:git-hash-object[1] and
+linkgit:git-rebase[1], among other git commands, can be used to create
+replacement objects from existing objects.
+
+If you want to replace many blobs, trees or commits that are part of a
+string of commits, you may just want to create a replacement string of
+commits and then only replace the commit at the tip of the target
+string of commits with the commit at the tip of the replacement string
+of commits.
+
 BUGS
 ----
 Comparing blobs or trees that have been replaced with those that
@@ -78,6 +91,9 @@ pending objects.
 
 SEE ALSO
 --------
+linkgit:git-hash-object[1]
+linkgit:git-filter-branch[1]
+linkgit:git-rebase[1]
 linkgit:git-tag[1]
 linkgit:git-branch[1]
 linkgit:git[1]
-- 
1.8.4.rc1.28.ge2684af

[PATCH v5 6/7] replace: allow long option names

[Christian Couder]

It is now standard practice in Git to have both short and long option
names. So let's give a long option name to the git replace options too.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 Documentation/git-replace.txt | 3 +++
 builtin/replace.c             | 6 +++---
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-replace.txt b/Documentation/git-replace.txt
index a2bd2ee..414000e 100644
--- a/Documentation/git-replace.txt
+++ b/Documentation/git-replace.txt
@@ -54,13 +54,16 @@ achieve the same effect as the `--no-replace-objects` option.
 OPTIONS
 -------
 -f::
+--force::
 	If an existing replace ref for the same object exists, it will
 	be overwritten (instead of failing).
 
 -d::
+--delete::
 	Delete existing replace refs for the given objects.
 
 -l <pattern>::
+--list <pattern>::
 	List replace refs for objects that match the given pattern (or
 	all if no pattern is given).
 	Typing "git replace" without arguments, also lists all replace
diff --git a/builtin/replace.c b/builtin/replace.c
index 95736d9..d4d1b75 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -128,9 +128,9 @@ int cmd_replace(int argc, const char **argv, const char *prefix)
 {
 	int list = 0, delete = 0, force = 0;
 	struct option options[] = {
-		OPT_BOOLEAN('l', NULL, &list, N_("list replace refs")),
-		OPT_BOOLEAN('d', NULL, &delete, N_("delete replace refs")),
-		OPT_BOOLEAN('f', NULL, &force, N_("replace the ref if it exists")),
+		OPT_BOOLEAN('l', "list", &list, N_("list replace refs")),
+		OPT_BOOLEAN('d', "delete", &delete, N_("delete replace refs")),
+		OPT_BOOLEAN('f', "force", &force, N_("replace the ref if it exists")),
 		OPT_END()
 	};
 
-- 
1.8.4.rc1.28.ge2684af

[PATCH v5 7/7] t6050-replace: use some long option names

[Christian Couder]

So that they are tested a little bit too.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 t/t6050-replace.sh | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/t/t6050-replace.sh b/t/t6050-replace.sh
index 09a2b49..7d47984 100755
--- a/t/t6050-replace.sh
+++ b/t/t6050-replace.sh
@@ -122,9 +122,9 @@ test_expect_success '"git replace" listing and deleting' '
      test "$HASH2" = "$(git replace -l)" &&
      test "$HASH2" = "$(git replace)" &&
      aa=${HASH2%??????????????????????????????????????} &&
-     test "$HASH2" = "$(git replace -l "$aa*")" &&
+     test "$HASH2" = "$(git replace --list "$aa*")" &&
      test_must_fail git replace -d $R &&
-     test_must_fail git replace -d &&
+     test_must_fail git replace --delete &&
      test_must_fail git replace -l -d $HASH2 &&
      git replace -d $HASH2 &&
      git show $HASH2 | grep "A U Thor" &&
@@ -147,7 +147,7 @@ test_expect_success '"git replace" resolves sha1' '
      git show $HASH2 | grep "O Thor" &&
      test_must_fail git replace $HASH2 $R &&
      git replace -f $HASH2 $R &&
-     test_must_fail git replace -f &&
+     test_must_fail git replace --force &&
      test "$HASH2" = "$(git replace)"
 '
 
@@ -272,7 +272,7 @@ test_expect_success 'replaced and replacement objects must be of the same type'
 
 test_expect_success '-f option bypasses the type check' '
 	git replace -f mytag $HASH1 &&
-	git replace -f HEAD^{tree} HEAD~1 &&
+	git replace --force HEAD^{tree} HEAD~1 &&
 	git replace -f HEAD^ $BLOB
 '
 
-- 
1.8.4.rc1.28.ge2684af

Re: [PATCH v5 1/7] replace: forbid replacing an object with one of a different type

[Junio C Hamano]

Christian Couder <chriscool@tuxfamily.org> writes:

> +	obj_type = sha1_object_info(object, NULL);
> +	repl_type = sha1_object_info(repl, NULL);

That we can do this is somewhat curious.  If an object is replaced
with a different one, would it mean that this code snippet is
totally bogus?

        type1 = sha1_object_info(sha1, &size1);
        area = xmalloc(size1);
        orig = read_sha1_file(sha1, &type0, &size0);
	memcpy(area, orig, size1);
	free(orig);

> +	if (!force && obj_type != repl_type)
> +		die("Objects must be of the same type.\n"
> +		    "'%s' points to a replaced object of type '%s'\n"
> +		    "while '%s' points to a replacement object of type '%s'.",
> +		    object_ref, typename(obj_type),
> +		    replace_ref, typename(repl_type));
> +
>  	if (read_ref(ref, prev))
>  		hashclr(prev);
>  	else if (!force)

Re: [PATCH v5 1/7] replace: forbid replacing an object with one of a different type

[Junio C Hamano]

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

> Christian Couder <chriscool@tuxfamily.org> writes:
>
>> +	obj_type = sha1_object_info(object, NULL);
>> +	repl_type = sha1_object_info(repl, NULL);
>
> That we can do this is somewhat curious....

Note that this was a comment on the sha1_object_info() API, which,
unlike read_sha1_file() API, does not seem to interact with the
"replace" mechanism.  I _think_ that needs to be rethought by
checking each call site, but for the purpose of this series, I think
this is the best we can do in this patch.

Will queue the whole series.

Thanks.