delta/git.git/refs.c, branch rs/reflog-exists

refs.c: add new functions reflog_exists and delete_reflog

2014-05-08T21:31:43+00:00

Add two new functions, reflog_exists and delete_reflog, to hide the internal
reflog implementation (that they are files under .git/logs/...) from callers.
Update checkout.c to use these functions in update_refs_for_switch instead of
building pathnames and calling out to file access functions. Update reflog.c
to use these to check if the reflog exists. Now there are still many places
in reflog.c where we are still leaking the reflog storage implementation but
this at least reduces the number of such dependencies by one. Finally
change two places in refs.c itself to use the new function to check if a ref
exists or not isntead of build-path-and-stat(). Now, this is strictly not all
that important since these are in parts of refs that are implementing the
actual file storage backend but on the other hand it will not hurt either.

Signed-off-by: Ronnie Sahlberg 
Acked-by: Michael Haggerty 
Signed-off-by: Junio C Hamano

Merge branch 'sh/use-hashcpy'

2014-03-18T20:51:05+00:00

* sh/use-hashcpy:
  Use hashcpy() when copying object names

Use hashcpy() when copying object names

2014-03-06T22:03:12+00:00

We invented hashcpy() to keep the abstraction of "object name"
behind it.  Use it instead of calling memcpy() with hard-coded
20-byte length when moving object names between pieces of memory.

Leave ppc/sha1.c as-is, because the function is about the SHA-1 hash
algorithm whose output is and will always be 20 bytes.

Helped-by: Michael Haggerty 
Helped-by: Duy Nguyen 
Signed-off-by: Sun He 
Signed-off-by: Junio C Hamano

use wildmatch() directly without fnmatch() wrapper

2014-02-20T22:15:46+00:00

Make it clear that we don't use fnmatch() anymore.

Signed-off-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

Merge branch 'mh/safe-create-leading-directories'

2014-01-27T18:45:33+00:00

Code clean-up and protection against concurrent write access to the
ref namespace.

* mh/safe-create-leading-directories:
  rename_tmp_log(): on SCLD_VANISHED, retry
  rename_tmp_log(): limit the number of remote_empty_directories() attempts
  rename_tmp_log(): handle a possible mkdir/rmdir race
  rename_ref(): extract function rename_tmp_log()
  remove_dir_recurse(): handle disappearing files and directories
  remove_dir_recurse(): tighten condition for removing unreadable dir
  lock_ref_sha1_basic(): if locking fails with ENOENT, retry
  lock_ref_sha1_basic(): on SCLD_VANISHED, retry
  safe_create_leading_directories(): add new error value SCLD_VANISHED
  cmd_init_db(): when creating directories, handle errors conservatively
  safe_create_leading_directories(): introduce enum for return values
  safe_create_leading_directories(): always restore slash at end of loop
  safe_create_leading_directories(): split on first of multiple slashes
  safe_create_leading_directories(): rename local variable
  safe_create_leading_directories(): add explicit "slash" pointer
  safe_create_leading_directories(): reduce scope of local variable
  safe_create_leading_directories(): fix format of "if" chaining

Merge branch 'mh/retire-ref-fetch-rules'

2014-01-27T18:44:07+00:00

Code simplification.

* mh/retire-ref-fetch-rules:
  refname_match(): always use the rules in ref_rev_parse_rules

rename_tmp_log(): on SCLD_VANISHED, retry

2014-01-21T21:47:28+00:00

If safe_create_leading_directories() fails because a file along the
path unexpectedly vanished, try again from the beginning.  Try at most
4 times.

Signed-off-by: Michael Haggerty 
Signed-off-by: Junio C Hamano

rename_tmp_log(): limit the number of remote_empty_directories() attempts

2014-01-21T21:47:24+00:00

This doesn't seem to be a likely error, but we've got the counter
anyway, so we might as well use it for an added bit of safety.

Please note that the first call to rename() is optimistic, and it is
normal for it to fail if there is a directory in the way.  So bump the
total number of allowed attempts to 4, to be sure that we can still
have at least 3 retries in the case of a race.

Signed-off-by: Michael Haggerty 
Signed-off-by: Junio C Hamano

rename_tmp_log(): handle a possible mkdir/rmdir race

2014-01-21T21:47:13+00:00

If a directory vanishes while renaming the temporary reflog file,
retry (up to 3 times).  This could happen if another process deletes
the directory created by safe_create_leading_directories() just before
we rename the file into the directory.

As far as I can tell, this race could not occur internal to git.  The
only time that a directory under $GIT_DIR/logs is deleted is if room
has to be made for a log file for a reference with the same name;
for example, in the following sequence:

    git branch foo/bar    # Creates file .git/logs/refs/heads/foo/bar
    git branch -d foo/bar # Deletes file but leaves .git/logs/refs/heads/foo/
    git branch foo        # Deletes .git/logs/refs/heads/foo/

But the only reason the last command deletes the directory is because
it wants to create a file with the same name.  So if another process
(e.g.,

    git branch foo/baz

) wants to create that directory, one of the two is doomed to failure
anyway because of a D/F conflict.

Signed-off-by: Michael Haggerty 
Signed-off-by: Junio C Hamano

rename_ref(): extract function rename_tmp_log()

2014-01-21T21:46:59+00:00

It's about to become a bit more complex.

Signed-off-by: Michael Haggerty 
Signed-off-by: Junio C Hamano