git/list[1] front-page[2] threads[3] people[4] search[5] about
 

[PATCH v3 01/11] replace: forbid replacing an object with one of a different type

From
Christian Couder <chriscool@tuxfamily.org>
Date
Aug 31, 2013, 19:12 UTC
Message-ID
<20130831191215.26699.18957.chriscool@tuxfamily.org>
In-Reply-To
<20130831190528.26699.33964.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 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..9a94769 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 (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.rc1.31.g530f5ce.dirty
Previous: Christian CouderNext: Philip Oakley
Message 2 of 33 in “Check replacement object type and minor updates”
  1. 00/11 Check replacement object type and minor updatesChristian Couder, Aug 31, 2013
  2. 01/11 replace: forbid replacing an object with one of a different typeChristian Couder, Aug 31, 2013
  3. Philip OakleyAug 31, 2013
  4. Christian CouderSep 1, 2013
  5. Philip OakleySep 1, 2013
  6. 02/11 Documentation/replace: state that objects must be of the same typeChristian Couder, Aug 31, 2013
  7. 03/11 t6050-replace: test that objects are of the same typeChristian Couder, Aug 31, 2013
  8. 04/11 t6050-replace: add test to clean up all the replace refsChristian Couder, Aug 31, 2013
  9. 05/11 Documentation/replace: add Creating Replacement Objects sectionChristian Couder, Aug 31, 2013
  10. Philip OakleyAug 31, 2013
  11. Christian CouderSep 1, 2013
  12. 06/11 replace: bypass the type check if -f option is usedChristian Couder, Aug 31, 2013
  13. 07/11 Documentation/replace: tell that -f option bypasses the type checkChristian Couder, Aug 31, 2013
  14. Philip OakleyAug 31, 2013
  15. Christian CouderSep 1, 2013
  16. Philip OakleySep 1, 2013
  17. Christian CouderSep 2, 2013
  18. Philip OakleySep 2, 2013
  19. Jonathan NiederSep 2, 2013
  20. Philip OakleySep 2, 2013
  21. Jonathan NiederSep 2, 2013
  22. Philip OakleySep 2, 2013
  23. Christian CouderSep 3, 2013
  24. 08/11 t6050-replace: check that -f option bypasses the type checkChristian Couder, Aug 31, 2013
  25. Eric SunshineSep 1, 2013
  26. Christian CouderSep 1, 2013
  27. 09/11 replace: allow long option namesChristian Couder, Aug 31, 2013
  28. 10/11 Documentation/replace: list long option namesChristian Couder, Aug 31, 2013
  29. 11/11 t6050-replace: use some long option namesChristian Couder, Aug 31, 2013
  30. Philip OakleyAug 31, 2013
  31. Christian CouderSep 1, 2013
  32. Eric SunshineSep 1, 2013
  33. Christian CouderSep 1, 2013

Read the whole thread, see it on lore, or plain text.

$ cat FOOTERMessages come from the public archive at lore.kernel.org/git, fetched every hour. The front page is chosen and written each morning by an AI editor and can be wrong; the threads themselves are the record. About and API. For agents: an MCP server at https://gitlist.dev/mcp, and any thread, story or person page as Markdown by adding .md to its URL (or sending Accept: text/markdown). Details in /llms.txt.