When we pack all objects, we use only the objects reachable
from references and reflogs. This misses any objects which
are reachable from the index, but not yet referenced.
By itself this isn't a big deal; the objects can remain
loose until they are actually used in a commit. However, it
does create a problem when we drop packed but unreachable
objects. We try to optimize out the writing of objects that
we will immediately prune, which means we must follow the
same rules as prune in determining what is reachable. And
prune uses the index for this purpose.
This is rather uncommon in practice, as objects in the index
would not usually have been packed in the first place. But
it could happen in a sequence like:
1. You make a commit on a branch that references blob X.
2. You repack, moving X into the pack.
3. You delete the branch (and its reflog), so that X is
unreferenced.
4. You "git add" blob X so that it is now referenced only
by the index.
5. You repack again with git-gc. The pack-objects we
invoke will see that X is neither referenced nor
recent and not bother loosening it.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This saves us from having to bump the rp_av count when we
add new traversal options.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This does the same thing as our custom code, so let's not
repeat ourselves.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There is currently no easy way to ask the revision traversal
machinery to include objects reachable from the index (e.g.,
blobs and trees that have not yet been committed). This
patch adds an option to do so.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is mostly used internally, but it does not hurt to
explain it.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It's not unreasonable to have a tag that points to a blob
that is not part of the normal history. We do this in
git.git to distribute gpg keys. However, we never explicitly
checked in our test suite that this actually works (i.e.,
that pack-objects actually sends the blob because of the tag
mentioning it).
It does in fact work fine, but a recent patch under
discussion broke this, and the test suite didn't notice.
Let's make the test suite more complete.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we call traverse_commit_list, we may have trees and
blobs in the pending array. As we process these, we pass the
"name" field from the pending entry as the path of the
object within the tree (which then becomes the root path if
we recurse into subtrees).
When we set up the traversal in prepare_revision_walk,
though, the "name" field of any pending trees and blobs is
likely to be the ref at which we found the object. We would
not want to make this part of the path (e.g., doing so would
make "git rev-list --objects v2.6.11-tree" in linux.git show
paths like "v2.6.11-tree/Makefile", which is nonsensical).
Therefore prepare_revision_walk sets the name field of each
pending tree and blobs to the empty string.
However, this leaves no room for a caller who does know the
correct path of a pending object to propagate that
information to the revision walker. We can fix this by
making two related changes:
1. Use the "path" field as the path instead of the "name"
field in traverse_commit_list. If the path is not set,
default to "" (which is what we always ended up with in
the current code, because of prepare_revision_walk).
2. In prepare_revision_walk, make a complete copy of the
entry. This makes the path field available to the
walker (if there is one), solving our problem.
Leaving the name field intact is now OK, as we do not
use it as a path due to point (1) above (and we can use
it to make more meaningful error messages if we want).
We also make the original "mode" field available to the
walker, though it does not actually use it.
Note that we still re-add the pending objects and free the
old ones (so we may strdup the path and name only to free
the old ones). This could be made more efficient by simply
copying the object_array entries that we are keeping.
However, that would require more restructuring of the code,
and is not done here.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When you resolve a sha1, you can optionally keep any context
found during the resolution, including the path and mode of
a tree entry (e.g., when looking up "HEAD:subdir/file.c").
The add_object_array_with_context function lets you then
attach that context to an entry in a list. Unfortunately,
the interface for doing so is horrible. The object_context
structure is large and most object_array users do not use
it. Therefore we keep a pointer to the structure to avoid
burdening other users too much. But that means when we do
use it that we must allocate the struct ourselves. And the
struct contains a fixed PATH_MAX-sized buffer, which makes
this wholly unsuitable for any large arrays.
We can observe that there is only a single user of the
"with_context" variant: builtin/grep.c. And in that use
case, the only element we care about is the path. We can
therefore store only the path as a pointer (the context's
mode field was redundant with the object_array_entry itself,
and nobody actually cared about the surrounding tree). This
still requires a strdup of the pathname, but at least we are
only consuming the minimum amount of memory for each string.
We can also handle the copying ourselves in
add_object_array_*, and free it as appropriate in
object_array_release_entry.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we try to write a loose object file, we first check
whether that object already exists. If so, we skip the
write as an optimization. However, this can interfere with
prune's strategy of using mtimes to mark files in progress.
For example, if a branch contains a particular tree object
and is deleted, that tree object may become unreachable, and
have an old mtime. If a new operation then tries to write
the same tree, this ends up as a noop; we notice we
already have the object and do nothing. A prune running
simultaneously with this operation will see the object as
old, and may delete it.
We can solve this by "freshening" objects that we avoid
writing by updating their mtime. The algorithm for doing so
is essentially the same as that of has_sha1_file. Therefore
we provide a new (static) interface "check_and_freshen",
which finds and optionally freshens the object. It's trivial
to implement freshening and simple checking by tweaking a
single parameter.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A recent commit taught git-prune to keep non-recent objects
that are reachable from recent ones. However, pack-objects,
when loosening unreachable objects, tries to optimize out
the write in the case that the object will be immediately
pruned. It now gets this wrong, since its rule does not
reflect the new prune code (and this can be seen by running
t6501 with a strategically placed repack).
Let's teach pack-objects similar logic.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we are loosening unreachable packed objects, we do not
bother to process objects that would simply be pruned
immediately anyway. The "would be pruned" check is a simple
comparison, but is about to get more complicated. Let's pull
it out into a separate function.
Note that this is slightly less efficient than the original,
which avoided even opening old packs, since no object in
them could pass the current check, which cares only about
the pack mtime. But the new rules will depend on the exact
object, so we need to perform the check even for old packs.
Note also that we fix a minor buglet when the pack mtime is
exactly the same as the expiration time. The prune code
considers that worth pruning, whereas our check here
considered it worth keeping. This wasn't a big deal. Besides
being unlikely to happen, the result was simply that the
object was loosened and then pruned, missing the
optimization. Still, we can easily fix it while we are here.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Our current strategy with prune is that an object falls into
one of three categories:
1. Reachable (from ref tips, reflogs, index, etc).
2. Not reachable, but recent (based on the --expire time).
3. Not reachable and not recent.
We keep objects from (1) and (2), but prune objects in (3).
The point of (2) is that these objects may be part of an
in-progress operation that has not yet updated any refs.
However, it is not always the case that objects for an
in-progress operation will have a recent mtime. For example,
the object database may have an old copy of a blob (from an
abandoned operation, a branch that was deleted, etc). If we
create a new tree that points to it, a simultaneous prune
will leave our tree, but delete the blob. Referencing that
tree with a commit will then work (we check that the tree is
in the object database, but not that all of its referred
objects are), as will mentioning the commit in a ref. But
the resulting repo is corrupt; we are missing the blob
reachable from a ref.
One way to solve this is to be more thorough when
referencing a sha1: make sure that not only do we have that
sha1, but that we have objects it refers to, and so forth
recursively. The problem is that this is very expensive.
Creating a parent link would require traversing the entire
object graph!
Instead, this patch pushes the extra work onto prune, which
runs less frequently (and has to look at the whole object
graph anyway). It creates a new category of objects: objects
which are not recent, but which are reachable from a recent
object. We do not prune these objects, just like the
reachable and recent ones.
This lets us avoid the recursive check above, because if we
have an object, even if it is unreachable, we should have
its referent. We can make a simple inductive argument that
with this patch, this property holds (that there are no
objects with missing referents in the repository):
0. When we have no objects, we have nothing to refer or be
referred to, so the property holds.
1. If we add objects to the repository, their direct
referents must generally exist (e.g., if you create a
tree, the blobs it references must exist; if you create
a commit to point at the tree, the tree must exist).
This is already the case before this patch. And it is
not 100% foolproof (you can make bogus objects using
`git hash-object`, for example), but it should be the
case for normal usage.
Therefore for any sequence of object additions, the
property will continue to hold.
2. If we remove objects from the repository, then we will
not remove a child object (like a blob) if an object
that refers to it is being kept. That is the part
implemented by this patch.
Note, however, that our reachability check and the
actual pruning are not atomic. So it _is_ still
possible to violate the property (e.g., an object
becomes referenced just as we are deleting it). This
patch is shooting for eliminating problems where the
mtimes of dependent objects differ by hours or days,
and one is dropped without the other. It does nothing
to help with short races.
Naively, the simplest way to implement this would be to add
all recent objects as tips to the reachability traversal.
However, this does not perform well. In a recently-packed
repository, all reachable objects will also be recent, and
therefore we have to look at each object twice. This patch
instead performs the reachability traversal, then follows up
with a second traversal for recent objects, skipping any
that have already been marked.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We typically iterate over the reachable objects in a
repository by starting at the tips and walking the graph.
There's no easy way to iterate over all of the objects,
including unreachable ones. Let's provide a way of doing so.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This drops our line count considerably, and should make
things more readable by keeping the counting logic separate
from the traversal.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The point of xsize_t is to safely cast an off_t into a size_t
(because we are about to mmap). But in count-objects, we are
summing the sizes in an off_t. Using xsize_t means that
count-objects could fail on a 32-bit system with a 4G
object (not likely, as other parts of git would fail, but
we should at least be correct here).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This saves us from manually traversing the directory
structure ourselves.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we mark all reachable objects for pruning, that
includes blobs mentioned by the index. However, we do not
mark these with the SEEN flag, as we do for objects that we
find by traversing (we also do not add them to the pending
list, but that is because there is nothing further to
traverse with them).
This doesn't cause any problems with prune, because it
checks only that the object exists in the global object
hash, and not its flags. However, let's mark these objects
to be consistent and avoid any later surprises.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Prune has to walk $GIT_DIR/objects/?? in order to find the
set of loose objects to prune. Other parts of the code
(e.g., count-objects) want to do the same. Let's factor it
out into a reusable for_each-style function.
Note that this is not quite a straight code movement. The
original code had strange behavior when it found a file of
the form "[0-9a-f]{2}/.{38}" that did _not_ contain all hex
digits. It executed a "break" from the loop, meaning that we
stopped pruning in that directory (but still pruned other
directories!). This was probably a bug; we do not want to
process the file as an object, but we should keep going
otherwise (and that is how the new code handles it).
We are also a little more careful with loose object
directories which fail to open. The original code silently
ignored any failures, but the new code will complain about
any problems besides ENOENT.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We want to add all reflog entries as tips for finding
reachable objects. The revision machinery can already do
this (to support "rev-list --reflog"); we can reuse that
code.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
To find the set of reachable objects, we add a bunch of
possible sources to our rev_info, call prepare_revision_walk,
and then launch into a custom walker that handles each
object top. This is a subset of what traverse_commit_list
does, so we can just reuse that code (it can also handle
more complex cases like UNINTERESTING commits and pathspecs,
but we don't use those features).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we enter prepare_revision_walk, we have zero or more
entries in our "pending" array. We disconnect that array
from the rev_info, and then process each entry:
1. If the entry is a commit and the --source option is in
effect, we keep a pointer to the object name.
2. Otherwise, we re-add the item to the pending list with
a blank name.
We then throw away the old array by freeing the array
itself, but do not touch the "name" field of each entry. For
any items of type (2), we leak the memory associated with
the name. This commit fixes that by calling object_array_clear,
which handles the cleanup for us.
That breaks (1), though, because it depends on the memory
pointed to by the name to last forever. We can solve that by
making a copy of the name. This is slightly less efficient,
but it shouldn't matter in practice, as we do it only for
the tip commits of the traversal.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There's currently no easy way to free the memory associated
with an object_array (and in most cases, we simply leak the
memory in a rev_info's pending array). Let's provide a
helper to make this easier to handle.
We can make use of it in list-objects.c, which does the same
thing by hand (but fails to free the "name" field of each
entry, potentially leaking memory).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is not a lot of code, but it's a logical construct that
should not need to be repeated (and we are about to add a
third repetition).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Otherwise, callers must do so or risk triggering warnings
-Wchar-subscript (and rightfully so; a signed char might
cause us to use a bogus negative index into the
hexval_table).
While we are dropping the now-unnecessary casts from the
caller in urlmatch.c, we can get rid of similar casts in
actually parsing the hex by using the hexval() helper, which
implicitly casts to unsigned (but note that we cannot
implement isxdigit in terms of hexval(), as it also casts
its return value to unsigned).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We check the return value of the callback and stop iterating
if it is non-zero. However, we do not make the non-zero
return value available to the caller, so they have no way of
knowing whether the operation succeeded or not (technically
they can keep their own error flag in the callback data, but
that is unlike our other for_each functions).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Usually running a test under "-v" makes it clear which
command is failing. However, sometimes it can be useful to
also see a complete trace of the shell commands being run in
the test. You can do so without any support from the test
suite by running "sh -x tXXXX-foo.sh". However, this
produces quite a large bit of output, as we see a trace of
the entire test suite.
This patch instead introduces a "-x" option to the test
scripts (i.e., "./tXXXX-foo.sh -x"). When enabled, this
turns on "set -x" only for the tests themselves. This can
still be a bit verbose, but should keep things to a more
manageable level. You can even use "--verbose-only" to see
the trace only for a specific test.
The implementation is a little invasive. We turn on the "set
-x" inside the "eval" of the test code. This lets the eval
itself avoid being reported in the trace (which would be
long, and redundant with the verbose listing we already
showed). And then after the eval runs, we do some trickery
with stderr to avoid showing the "set +x" to the user.
We also show traces for test_cleanup functions (since they
can impact the test outcome, too). However, we do avoid
running the noop ":" cleanup (the default if the test does
not use test_cleanup at all), as it creates unnecessary
noise in the "set -x" output.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
For small outputs, we sometimes use:
test "$(some_cmd)" = "something we expect"
instead of a full test_cmp. The downside of this is that
when it fails, there is no output at all from the script.
Let's introduce a small helper to make tests easier to
debug.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is slightly more robust (checking "! test -f" would not
notice a directory of the same name, though that is not
likely to happen here). It also makes debugging easier, as
the test script will output a message on failure.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When running a required clean filter, we do not have to mmap the
original before feeding the filter. Instead, stream the file
contents directly to the filter and process its output.
* sp/stream-clean-filter:
sha1_file: don't convert off_t to size_t too early to avoid potential die()
convert: stream from fd to required clean filter to reduce used address space
copy_fd(): do not close the input file descriptor
mmap_limit: introduce GIT_MMAP_LIMIT to allow testing expected mmap size
memory_limit: use git_env_ulong() to parse GIT_ALLOC_LIMIT
config.c: add git_env_ulong() to parse environment variable
convert: drop arguments other than 'path' from would_convert_to_git()
Allow "git push" request to be signed, so that it can be verified and
audited, using the GPG signature of the person who pushed, that the
tips of branches at a public repository really point the commits
the pusher wanted to, without having to "trust" the server.
* jc/push-cert: (24 commits)
receive-pack::hmac_sha1(): copy the entire SHA-1 hash out
signed push: allow stale nonce in stateless mode
signed push: teach smart-HTTP to pass "git push --signed" around
signed push: fortify against replay attacks
signed push: add "pushee" header to push certificate
signed push: remove duplicated protocol info
send-pack: send feature request on push-cert packet
receive-pack: GPG-validate push certificates
push: the beginning of "git push --signed"
pack-protocol doc: typofix for PKT-LINE
gpg-interface: move parse_signature() to where it should be
gpg-interface: move parse_gpg_output() to where it should be
send-pack: clarify that cmds_sent is a boolean
send-pack: refactor inspecting and resetting status and sending commands
send-pack: rename "new_refs" to "need_pack_data"
receive-pack: factor out capability string generation
send-pack: factor out capability string generation
send-pack: always send capabilities
send-pack: refactor decision to send update per ref
send-pack: move REF_STATUS_REJECT_NODELETE logic a bit higher
...
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
setitmer(2) and related API elements can be configured from
Makefile but autoconf did not know about it.
* jt/itimer-autoconf:
autoconf: check for setitimer()
autoconf: check for struct itimerval
git-compat-util.h: add missing semicolon after struct itimerval
"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).
* sb/merge-recursive-copy-paste-fix:
merge-recursive: remove stale commented debugging code
merge-recursive: fix copy-paste mistake
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
"git fsck" failed to report that it found corrupt objects via its
exit status in some cases.
* jk/fsck-exit-code-fix:
fsck: return non-zero status on missing ref tips
fsck: exit with non-zero status upon error from fsck_obj()
"git config --add section.var val" used to lose existing
section.var whose value was an empty string.
* ta/config-add-to-empty-or-true-fix:
config: avoid a funny sentinel value "a^"
make config --add behave correctly for empty and NULL values
Reachability check (used in "git prune" and friends) did not add a
detached HEAD as a starting point to traverse objects still in use.
* mk/reachable-protect-detached-head:
reachable.c: add HEAD to reachability starting commits
An attempt to remove the entire tree in the "git fast-import" input
stream caused it to misbehave.
* mb/fast-import-delete-root:
fast-import: fix segfault in store_tree()
t9300: test filedelete command
When receiving an invalid pack stream that records the same object
twice, multiple threads got confused due to a race.
* jk/index-pack-threading-races:
index-pack: fix race condition with duplicate bases
