refs.c: ref_transaction_commit should not free the transaction

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
refs.c: constify the sha arguments for ref_transaction_create|delete|update

ref_transaction_create|delete|update has no need to modify the sha1
arguments passed to it so it should use const unsigned char* instead
of unsigned char*.

Some functions, such as fast_forward_to(), already have its old/new
sha1 arguments as consts. This function will at some point need to
use ref_transaction_update() in which case this change is required.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
refs.c: allow passing NULL to ref_transaction_free

Allow ref_transaction_free(NULL) as a no-op. This makes ref_transaction_free
easier to use and more similar to plain 'free'.

In particular, it lets us rollback unconditionally as part of cleanup code
after setting 'transaction = NULL' if a transaction has been committed or
rolled back already.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
refs.c: add a strbuf argument to ref_transaction_commit for error logging

Add a strbuf argument to _commit so that we can pass an error string back to
the caller. So that we can do error logging from the caller instead of from
_commit.

Longer term plan is to first convert all callers to use onerr==QUIET_ON_ERR
and craft any log messages from the callers themselves and finally remove the
onerr argument completely.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
refs.c: add an err argument to repack_without_refs

Update repack_without_refs to take an err argument and update it if there
is a failure. Pass the err variable from ref_transaction_commit to this
function so that callers can print a meaningful error message if _commit
fails due to a problem in repack_without_refs.

Add a new function unable_to_lock_strbuf that takes a strbuf argument and
fills in the reason for the failure.

In commit_packed_refs, make sure that we propagate any errno that
commit_lock_file might have set back to our caller.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
refs.c: make ref_update_reject_duplicates take a strbuf argument for errors

Make ref_update_reject_duplicates return any error that occurs through a
new strbuf argument. This means that when a transaction commit fails in
this function we will now be able to pass a helpful error message back to the
caller.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
refs.c: add an err argument to delete_ref_loose

Add an err argument to delete_loose_ref so that we can pass a descriptive
error string back to the caller. Pass the err argument from transaction
commit to this function so that transaction users will have a nice error
string if the transaction failed due to delete_loose_ref.

Add a new function unlink_or_err that we can call from delete_ref_loose. This
function is similar to unlink_or_warn except that we can pass it an err
argument. If err is non-NULL the function will populate err instead of
printing a warning().

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
refs.c: make update_ref_write update a strbuf on failure

Change update_ref_write to also update an error strbuf on failure.
This makes the error available to ref_transaction_commit callers if the
transaction failed due to update_ref_sha1/write_ref_sha1 failures.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
update-ref.c: log transaction error from the update_ref

Call ref_transaction_commit with QUIET_ON_ERR and use the strbuf that is
returned to print a log message if/after the transaction fails.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
refs.c: remove the onerr argument to ref_transaction_commit

Since all callers now use QUIET_ON_ERR we no longer need to provide an onerr
argument any more. Remove the onerr argument from the ref_transaction_commit
signature.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
refs.c: change ref_transaction_update() to do error checking and return status

Update ref_transaction_update() do some basic error checking and return
non-zero on error. Update all callers to check ref_transaction_update() for
error. There are currently no conditions in _update that will return error but
there will be in the future. Add an err argument that will be updated on
failure. In future patches we will start doing both locking and checking
for name conflicts in _update instead of _commit at which time this function
will start returning errors for these conditions.

Also check for BUGs during update and die(BUG:...) if we are calling
_update with have_old but the old_sha1 pointer is NULL.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
refs.c: change ref_transaction_create to do error checking and return status

Do basic error checking in ref_transaction_create() and make it return
non-zero on error. Update all callers to check the result of
ref_transaction_create(). There are currently no conditions in _create that
will return error but there will be in the future. Add an err argument that
will be updated on failure.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
refs.c: update ref_transaction_delete to check for error and return status

Change ref_transaction_delete() to do basic error checking and return
non-zero of error. Update all callers to check the return for
ref_transaction_delete(). There are currently no conditions in _delete that
will return error but there will be in the future. Add an err argument that
will be updated on failure.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
refs.c: make ref_transaction_begin take an err argument

Add an err argument to _begin so that on non-fatal failures in future ref
backends we can report a nice error back to the caller.
While _begin can currently never fail for other reasons than OOM, in which
case we die() anyway, we may add other types of backends in the future.
For example, a hypothetical MySQL backend could fail in _being with
"Can not connect to MySQL server. No route to host".

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
refs.c: add transaction.status and track OPEN/CLOSED/ERROR

Track the status of a transaction in a new status field. Check the field for
sanity, i.e. that status must be OPEN when _commit/_create/_delete or
_update is called or else die(BUG:...)

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
tag.c: use ref transactions when doing updates

Change tag.c to use ref transactions for all ref updates.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
replace.c: use the ref transaction functions for updates

Update replace.c to use ref transactions for updates.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
commit.c: use ref transactions for updates

Change commit.c to use ref transactions for all ref updates.
Make sure we pass a NULL pointer to ref_transaction_update if have_old
is false.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
sequencer.c: use ref transactions for all ref updates

Change to use ref transactions for all updates to refs.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
fast-import.c: change update_branch to use ref transactions

Change update_branch() to use ref transactions for updates.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>