lockfile: change lock_file::filename into a strbuf
For now, we still make sure to allocate at least PATH_MAX characters
for the strbuf because resolve_symlink() doesn't know how to expand
the space for its return value. (That will be fixed in a moment.)
Another alternative would be to just use a strbuf as scratch space in
lock_file() but then store a pointer to the naked string in struct
lock_file. But lock_file objects are often reused. By reusing the
same strbuf, we can avoid having to reallocate the string most times
when a lock_file object is reused.
Helped-by: Torsten Bögershausen <tboegi@web.de> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
try_merge_strategy(): use a statically-allocated lock_file object
Even the one lockfile object needn't be allocated each time the
function is called. Instead, define one statically-allocated
lock_file object and reuse it for every call.
Suggested-by: Jeff King <peff@peff.net> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
By the time the "if" block is entered, the lock_file instance from the
main function block is no longer in use, so re-use that one instead of
allocating a second one.
Note that the "lock" variable in the "if" block shadowed the "lock"
variable at function scope, so the only change needed is to remove the
inner definition.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
The function remove_lock_file_on_signal() is used as a signal handler.
It is not realistic to make the signal handler conform strictly to the
C standard, which is very restrictive about what a signal handler is
allowed to do. But let's increase the likelihood that it will work:
The lock_file_list global variable and several fields from struct
lock_file are used by the signal handler. Declare those values
"volatile" to (1) force the main process to write the values to RAM
promptly, and (2) prevent updates to these fields from being reordered
in a way that leaves an opportunity for a jump to the signal handler
while the object is in an inconsistent state.
We don't mark the filename field volatile because that would prevent
the use of strcpy(), and it is anyway unlikely that a compiler
re-orders a strcpy() call across other expressions. So in practice it
should be possible to get away without "volatile" in the "filename"
case.
Suggested-by: Johannes Sixt <j6t@kdbg.org> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Because remove_lock_file() can be called any time by the signal
handler, it is important that any lock_file objects that are in the
lock_file_list are always in a valid state. And since lock_file
objects are often reused (but are never removed from lock_file_list),
that means we have to be careful whenever mutating a lock_file object
to always keep it in a well-defined state.
This was formerly not the case, because part of the state was encoded
by setting lk->filename to the empty string vs. a valid filename. It
is wrong to assume that this string can be updated atomically; for
example, even
strcpy(lk->filename, value)
is unsafe. But the old code was even more reckless; for example,
strcpy(lk->filename, path);
if (!(flags & LOCK_NODEREF))
resolve_symlink(lk->filename, max_path_len);
strcat(lk->filename, ".lock");
During the call to resolve_symlink(), lk->filename contained the name
of the file that was being locked, not the name of the lockfile. If a
signal were raised during that interval, then the signal handler would
have deleted the valuable file!
We could probably continue to use the filename field to encode the
state by being careful to write characters 1..N-1 of the filename
first, and then overwrite the NUL at filename[0] with the first
character of the filename, but that would be awkward and error-prone.
So, instead of using the filename field to determine whether the
lock_file object is active, add a new field "lock_file::active" for
this purpose. Be careful to set this field only when filename really
contains the name of a file that should be deleted on cleanup.
Helped-by: Johannes Sixt <j6t@kdbg.org> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
git_config_set_multivar_in_file(): avoid call to rollback_lock_file()
After commit_lock_file() is called, then the lock_file object is
necessarily either committed or rolled back. So there is no need to
call rollback_lock_file() again in either of these cases.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
dump_marks(): remove a redundant call to rollback_lock_file()
When commit_lock_file() fails, it now always calls
rollback_lock_file() internally, so there is no need to call that
function here.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Reviewed-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* Document the behavior of commit_lock_file() when it fails, namely
that it rolls back the lock_file object and sets errno
appropriately.
* Document the behavior of rollback_lock_file() when called for a
lock_file object that has already been committed or rolled back,
namely that it is a NOOP.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
commit_lock_file(): rollback lock file on failure to rename
If rename() fails, call rollback_lock_file() to delete the lock file
(in case it is still present) and reset the filename field to the
empty string so that the lockfile object is left in a valid state.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
If closing an open lockfile fails, then we cannot be sure of the
contents of the lockfile, so there is nothing sensible to do but
delete it. This change also insures that the lock_file object is left
in a defined state in this error path (namely, unlocked).
The only caller that is ultimately affected by this change is
try_merge_strategy() -> write_locked_index(), which can call
close_lock_file() via various execution paths. This caller uses a
static lock_file object which previously could have been reused after
a failed close_lock_file() even though it was still in locked state.
This change causes the lock_file object to be unlocked on failure,
thus fixing this error-handling path.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
commit_lock_file(): die() if called for unlocked lockfile object
It was previously a bug to call commit_lock_file() with a lock_file
object that was not active (an illegal access would happen within the
function). It was presumably never done, but this would be an easy
programming error to overlook. So before continuing, do a consistency
check that the lock_file object really is locked.
Helped-by: Johannes Sixt <j6t@kdbg.org> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Reviewed-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
lock_file(): exit early if lockfile cannot be opened
This is a bit easier to read than the old version, which nested part
of the non-error code in an "if" block.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Reviewed-by: Ronnie Sahlberg <sahlberg@google.com> Reviewed-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
prepare_index(): declare return value to be (const char *)
Declare the return value to be const to make it clear that we aren't
giving callers permission to write over the string that it points at.
(The return value is the filename field of a struct lock_file, which
can be used by a signal handler at any time and therefore shouldn't be
tampered with.)
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
delete_ref_loose(): don't muck around in the lock_file's filename
It's bad manners. Especially since there could be a signal during the
call to unlink_or_warn(), in which case the signal handler will see
the wrong filename and delete the reference file, leaving the lockfile
behind.
So make our own copy to work with.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
lockfile.c: document the various states of lock_file objects
Document the valid states of lock_file objects, how they get into each
state, and how the state is encoded in the object's fields.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Reviewed-by: Ronnie Sahlberg <sahlberg@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
lock_file(): always initialize and register lock_file object
The purpose of this change is to make the state diagram for
lock_file objects simpler and deterministic.
If locking fails, lock_file() sometimes leaves the lock_file object
partly initialized, but sometimes not. It sometimes registers the
object in lock_file_list, but sometimes not. This makes the state
diagram for lock_file objects effectively indeterministic and hard
to reason about. A future patch will also change the filename field
into a strbuf, which needs more involved initialization, so it will
become even more important that the state of a lock_file object is
well-defined after a failed attempt to lock.
The ambiguity doesn't currently have any ill effects, because
lock_file objects cannot be removed from the lock_file_list anyway.
But to make it easier to document and reason about the code, make
this behavior consistent: *always* initialize the lock_file object
and *always* register it in lock_file_list the first time it is
used, regardless of whether an error occurs.
While we're at it, make sure that all of the lock_file fields are
initialized to values appropriate for an unlocked object; the caller
is only responsible for making sure that on_list is set to zero before
the first time it is used.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
hold_lock_file_for_append(): release lock on errors
If there is an error copying the old contents to the lockfile, roll
back the lockfile before exiting so that the lockfile is not held
until process cleanup.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Reviewed-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
lockfile: unlock file if lockfile permissions cannot be adjusted
If the call to adjust_shared_perm() fails, lock_file returns -1, which
to the caller looks like any other failure to lock the file. So in
this case, roll back the lockfile before returning so that the lock
file is deleted immediately and the lockfile object is left in a
predictable state (namely, unlocked). Previously, the lockfile was
retained until process cleanup in this situation.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Reviewed-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
When rolling back the lockfile, call close_lock_file() so that the
lock_file's fd field gets set back to -1. This keeps the lock_file
object in a valid state, which is important because these objects are
allowed to be reused. It also makes it unnecessary to check whether
the file has already been closed, because close_lock_file() takes care
of that.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Reviewed-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
rollback_lock_file(): exit early if lock is not active
Eliminate a layer of nesting.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Reviewed-by: Ronnie Sahlberg <sahlberg@google.com> Reviewed-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
rollback_lock_file(): do not clear filename redundantly
It is only necessary to clear the lock_file's filename field if it was
not already clear.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Reviewed-by: Ronnie Sahlberg <sahlberg@google.com> Reviewed-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
close_lock_file(): exit (successfully) if file is already closed
Suggested-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Document a couple more functions and the flags argument as used by
hold_lock_file_for_update() and hold_lock_file_for_append().
Reorganize the document to make it more accessible.
Helped-by: Jonathan Nieder <jrnieder@gmail.com> Helped-by: Junio Hamano <gitster@pobox.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
unable_to_lock_die(): rename function from unable_to_lock_index_die()
This function is used for other things besides the index, so rename it
accordingly.
Suggested-by: Jeff King <peff@peff.net> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Reviewed-by: Ronnie Sahlberg <sahlberg@google.com> Reviewed-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git merge-recursive" had a small bug that could have made it
mishandle "one side deleted, the other side did not touch it" in a
rare corner case, where the other side actually did touch to cause
the blob object names to be different but both blobs before and
after the change normalize to the same (e.g. correcting mistake to
check in a blob with CRLF line endings by replacing it with another
blob that records the same contents with LF line endings).
We used to get confused when a process called us with SIGPIPE
ignored; we do want to die with SIGPIPE when the output is not
read by default, and do ignore the signal when appropriate.
* pr/use-default-sigpipe-setting:
mingw.h: add dummy functions for sigset_t operations
unblock and unignore SIGPIPE
* so/rebase-doc:
Documentation/git-rebase.txt: <upstream> must be given to specify <branch>
Documentation/git-rebase.txt: -f forces a rebase that would otherwise be a no-op
Some MUAs mangled a line in a message that begins with "From " to
">From " when writing to a mailbox file and feeding such an input
to "git am" used to lose such a line.
* jk/mbox-from-line:
mailinfo: work around -Wstring-plus-int warning
mailinfo: make ">From" in-body header check more robust
"rev-parse --verify --quiet $name" is meant to quietly exit with a
non-zero status when $name is not a valid object name, but still
gave error messages in some cases.
* da/rev-parse-verify-quiet:
stash: prefer --quiet over shell redirection of the standard error stream
refs: make rev-parse --quiet actually quiet
t1503: use test_must_be_empty
Documentation: a note about stdout for git rev-parse --verify --quiet
The pretty-format specifier "%d", which expanded to " (tagname)"
for a tagged commit, gained a cousin "%D" that just gives the
"tagname" without frills.
* hj/pretty-naked-decoration:
pretty: add %D format specifier
Merge branch 'maint' of git://github.com/git-l10n/git-po into maint
* 'maint' of git://github.com/git-l10n/git-po:
l10n: de.po: use comma before "um"
l10n: de.po: change Email to E-Mail
po/TEAMS: add new member to German translation team
* jk/prune-packed-server-info:
repack: call prune_packed_objects() and update_server_info() directly
server-info: clean up after writing info/packs
make update-server-info more robust
prune-packed: fix minor memory leak
"hash-object" learned a new "--literally" option to hash any random
garbage into a loose object, to allow us to create a test data for
mechanisms to catch corrupt objects.
* jc/hash-object:
hash-object: add --literally option
hash-object: pass 'write_object' as a flag
hash-object: reduce file-scope statics
Teach "git fsck" to inspect the contents of annotated tag objects.
* js/fsck-tag-validation:
Make sure that index-pack --strict checks tag objects
Add regression tests for stricter tag fsck'ing
fsck: check tag objects' headers
Make sure fsck_commit_buffer() does not run out of the buffer
fsck_object(): allow passing object data separately from the object itself
Refactor type_from_string() to allow continuing after detecting an error
Optimize the check to see if a ref $F can be created by making sure
no existing ref has $F/ as its prefix, which especially matters in
a repository with a large number of existing refs.
* jk/faster-name-conflicts:
refs: speed up is_refname_available
The following issue was found by scan.coverity.com (ID: 1049510),
and claimed to be likely a copy-paste mistake.
Introduced in 331a1838b (2010-07-02, Try normalizing files
to avoid delete/modify conflicts when merging), which is
quite a long time ago, so I'm rather unsure if it's of any impact
or just went unnoticed.
The line after the changed line has a comparison of 'o.len' to 'a.len',
so we should assume the lengths may be different.
I'd be happy to have a test for this bug(?) attached to
t6031-merge-recursive.sh, but I did not manage to
come up with a test in a reasonable amount of time.
Signed-off-by: Stefan Beller <stefanbeller@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
The just-released Apple Xcode 6.0.1 has -Wstring-plus-int enabled by
default which complains about pointer arithmetic applied to a string
literal:
builtin/mailinfo.c:303:24: warning:
adding 'long' to a string does not append to the string
return !memcmp(SAMPLE + (cp - line), cp, strlen(SAMPLE) ...
~~~~~~~^~~~~~~~~~~~~
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
mingw.h: add dummy functions for sigset_t operations
Windows does not have POSIX-like signals, and so we ignore all
operations on the non-existent signal mask machinery.
Do not turn sigemptyset into a function, but leave it a macro that
erases the code in the argument because it is used to set sa_mask
of a struct sigaction, but our dummy in mingw.h does not have that
member.
Signed-off-by: Johannes Sixt <j6t@kdbg.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'jn/unpack-trees-checkout-m-carry-deletion' into maint
* jn/unpack-trees-checkout-m-carry-deletion:
checkout -m: attempt merge when deletion of path was staged
unpack-trees: use 'cuddled' style for if-else cascade
unpack-trees: simplify 'all other failures' case
* jc/apply-ws-prefix:
apply: omit ws check for excluded paths
apply: hoist use_patch() helper for path exclusion up
apply: use the right attribute for paths in non-Git patches
* jk/pretty-empty-format:
pretty: make empty userformats truly empty
pretty: treat "--format=" as an empty userformat
revision: drop useless string offset when parsing "--pretty"