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

From
Christian Couder <chriscool@tuxfamily.org>
Date
Sep 6, 2013, 05:10 UTC
Message-ID
<20130906051100.6657.41248.chriscool@tuxfamily.org>
In-Reply-To
<20130906050702.6657.25651.chriscool@tuxfamily.org>

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
Previous: Christian CouderNext: Junio C Hamano
Message 2 of 10 in “Check replacement object type and minor updates”
  1. 0/7 Check replacement object type and minor updatesChristian Couder, Sep 6, 2013
  2. 1/7 replace: forbid replacing an object with one of a different typeChristian Couder, Sep 6, 2013
  3. Junio C HamanoSep 6, 2013
  4. Junio C HamanoSep 6, 2013
  5. 2/7 Documentation/replace: state that objects must be of the same typeChristian Couder, Sep 6, 2013
  6. 3/7 t6050-replace: test that objects are of the same typeChristian Couder, Sep 6, 2013
  7. 4/7 t6050-replace: add test to clean up all the replace refsChristian Couder, Sep 6, 2013
  8. 5/7 Documentation/replace: add Creating Replacement Objects sectionChristian Couder, Sep 6, 2013
  9. 6/7 replace: allow long option namesChristian Couder, Sep 6, 2013
  10. 7/7 t6050-replace: use some long option namesChristian Couder, Sep 6, 2013

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