Commit Graph

98 Commits

Author SHA1 Message Date
Junio C Hamano
208ee59861 Merge branch 'nd/reject-empty-shallow-request'
"git fetch --shallow-since=<cutoff>" that specifies the cut-off
point that is newer than the existing history used to end up
grabbing the entire history.  Such a request now errors out.

* nd/reject-empty-shallow-request:
  upload-pack: reject shallow requests that would return nothing
2018-06-25 13:22:40 -07:00
Junio C Hamano
b3b2aaf0fd Merge branch 'nd/commit-util-to-slab'
The in-core "commit" object had an all-purpose "void *util" field,
which was tricky to use especially in library-ish part of the
code.  All of the existing uses of the field has been migrated to a
more dedicated "commit-slab" mechanism and the field is eliminated.

* nd/commit-util-to-slab:
  commit.h: delete 'util' field in struct commit
  merge: use commit-slab in merge remote desc instead of commit->util
  log: use commit-slab in prepare_bases() instead of commit->util
  show-branch: note about its object flags usage
  show-branch: use commit-slab for commit-name instead of commit->util
  name-rev: use commit-slab for rev-name instead of commit->util
  bisect.c: use commit-slab for commit weight instead of commit->util
  revision.c: use commit-slab for show_source
  sequencer.c: use commit-slab to associate todo items to commits
  sequencer.c: use commit-slab to mark seen commits
  shallow.c: use commit-slab for commit depth instead of commit->util
  describe: use commit-slab for commit names instead of commit->util
  blame: use commit-slab for blame suspects instead of commit->util
  commit-slab: support shared commit-slab
  commit-slab.h: code split
2018-06-25 13:22:35 -07:00
Nguyễn Thái Ngọc Duy
e34de73c56 upload-pack: reject shallow requests that would return nothing
Shallow clones with --shallow-since or --shalow-exclude work by
running rev-list to get all reachable commits, then draw a boundary
between reachable and unreachable and send "shallow" requests based on
that.

The code does miss one corner case: if rev-list returns nothing, we'll
have no border and we'll send no shallow requests back to the client
(i.e. no history cuts). This essentially means a full clone (or a full
branch if the client requests just one branch). One example is the
oldest commit is older than what is specified by --shallow-since.

To avoid this, if rev-list returns nothing, we abort the clone/fetch.
The user could adjust their request (e.g. --shallow-since further back
in the past) and retry.

Another possible option for this case is to fall back to a default
depth (like depth 1). But I don't like too much magic that way because
we may return something unexpected to the user. If they request
"history since 2008" and we return a single depth at 2000, that might
break stuff for them. It is better to tell them that something is
wrong and let them take the best course of action.

Note that we need to die() in get_shallow_commits_by_rev_list()
instead of just checking for empty result from its caller
deepen_by_rev_list() and handling the error there. The reason is,
empty result could be a valid case: if you have commits in year 2013
and you request --shallow-since=year.2000 then you should get a full
clone (i.e. empty result).

Reported-by: Andreas Krey <a.krey@gmx.de>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-06-04 11:03:10 +09:00
Junio C Hamano
50f08db594 Merge branch 'js/use-bug-macro'
Developer support update, by using BUG() macro instead of die() to
mark codepaths that should not happen more clearly.

* js/use-bug-macro:
  BUG_exit_code: fix sparse "symbol not declared" warning
  Convert remaining die*(BUG) messages
  Replace all die("BUG: ...") calls by BUG() ones
  run-command: use BUG() to report bugs, not die()
  test-tool: help verifying BUG() code paths
2018-05-30 14:04:07 +09:00
Nguyễn Thái Ngọc Duy
58dbe58faa shallow.c: use commit-slab for commit depth instead of commit->util
It's done so that commit->util can be removed. See more explanation in
the commit that removes commit->util.

While at there, plug a leak for keeping track of depth in this code.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-05-21 14:07:20 +09:00
Martin Ågren
b227586831 lock_file: make function-local locks non-static
Placing `struct lock_file`s on the stack used to be a bad idea, because
the temp- and lockfile-machinery would keep a pointer into the struct.
But after 076aa2cbd (tempfile: auto-allocate tempfiles on heap,
2017-09-05), we can safely have lockfiles on the stack. (This applies
even if a user returns early, leaving a locked lock behind.)

These `struct lock_file`s are local to their respective functions and we
can drop their staticness.

For good measure, I have inspected these sites and come to believe that
they always release the lock, with the possible exception of bailing out
using `die()` or `exit()` or by returning from a `cmd_foo()`.

As pointed out by Jeff King, it would be bad if someone held on to a
`struct lock_file *` for some reason. After some grepping, I agree with
his findings: no-one appears to be doing that.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-05-10 14:54:45 +09:00
Johannes Schindelin
033abf97fc Replace all die("BUG: ...") calls by BUG() ones
In d8193743e0 (usage.c: add BUG() function, 2017-05-12), a new macro
was introduced to use for reporting bugs instead of die(). It was then
subsequently used to convert one single caller in 588a538ae5
(setup_git_env: convert die("BUG") to BUG(), 2017-05-12).

The cover letter of the patch series containing this patch
(cf 20170513032414.mfrwabt4hovujde2@sigill.intra.peff.net) is not
terribly clear why only one call site was converted, or what the plan
is for other, similar calls to die() to report bugs.

Let's just convert all remaining ones in one fell swoop.

This trick was performed by this invocation:

	sed -i 's/die("BUG: /BUG("/g' $(git grep -l 'die("BUG' \*.c)

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-05-06 19:06:13 +09:00
Junio C Hamano
69c54c7284 Merge branch 'ma/leakplugs'
Memory leaks in various codepaths have been plugged.

* ma/leakplugs:
  pack-bitmap[-write]: use `object_array_clear()`, don't leak
  object_array: add and use `object_array_pop()`
  object_array: use `object_array_clear()`, not `free()`
  leak_pending: use `object_array_clear()`, not `free()`
  commit: fix memory leak in `reduce_heads()`
  builtin/commit: fix memory leak in `prepare_index()`
2017-09-29 11:23:43 +09:00
Junio C Hamano
c50424a6f0 Merge branch 'jk/write-in-full-fix'
Many codepaths did not diagnose write failures correctly when disks
go full, due to their misuse of write_in_full() helper function,
which have been corrected.

* jk/write-in-full-fix:
  read_pack_header: handle signed/unsigned comparison in read result
  config: flip return value of store_write_*()
  notes-merge: use ssize_t for write_in_full() return value
  pkt-line: check write_in_full() errors against "< 0"
  convert less-trivial versions of "write_in_full() != len"
  avoid "write_in_full(fd, buf, len) != len" pattern
  get-tar-commit-id: check write_in_full() return against 0
  config: avoid "write_in_full(fd, buf, len) < len" pattern
2017-09-25 15:24:06 +09:00
Martin Ågren
7199203937 object_array: add and use object_array_pop()
In a couple of places, we pop objects off an object array `foo` by
decreasing `foo.nr`. We access `foo.nr` in many places, but most if not
all other times we do so read-only, e.g., as we iterate over the array.
But when we change `foo.nr` behind the array's back, it feels a bit
nasty and looks like it might leak memory.

Leaks happen if the popped element has an allocated `name` or `path`.
At the moment, that is not the case. Still, 1) the object array might
gain more fields that want to be freed, 2) a code path where we pop
might start using names or paths, 3) one of these code paths might be
copied to somewhere where we do, and 4) using a dedicated function for
popping is conceptually cleaner.

Introduce and use `object_array_pop()` instead. Release memory in the
new function. Document that popping an object leaves the associated
elements in limbo.

The converted places were identified by grepping for "\.nr\>" and
looking for "--".

Make the new function return NULL on an empty array. This is consistent
with `pop_commit()` and allows the following:

	while ((o = object_array_pop(&foo)) != NULL) {
		// do something
	}

But as noted above, we don't need to go out of our way to avoid reading
`foo.nr`. This is probably more readable:

	while (foo.nr) {
		... o = object_array_pop(&foo);
		// do something
	}

The name of `object_array_pop()` does not quite align with
`add_object_array()`. That is unfortunate. On the other hand, it matches
`object_array_clear()`. Arguably it's `add_...` that is the odd one out,
since it reads like it's used to "add" an "object array". For that
reason, side with `object_array_clear()`.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-24 10:06:04 +09:00
Jeff King
06f46f237a avoid "write_in_full(fd, buf, len) != len" pattern
The return value of write_in_full() is either "-1", or the
requested number of bytes[1]. If we make a partial write
before seeing an error, we still return -1, not a partial
value. This goes back to f6aa66cb95 (write_in_full: really
write in full or return error on disk full., 2007-01-11).

So checking anything except "was the return value negative"
is pointless. And there are a couple of reasons not to do
so:

  1. It can do a funny signed/unsigned comparison. If your
     "len" is signed (e.g., a size_t) then the compiler will
     promote the "-1" to its unsigned variant.

     This works out for "!= len" (unless you really were
     trying to write the maximum size_t bytes), but is a
     bug if you check "< len" (an example of which was fixed
     recently in config.c).

     We should avoid promoting the mental model that you
     need to check the length at all, so that new sites are
     not tempted to copy us.

  2. Checking for a negative value is shorter to type,
     especially when the length is an expression.

  3. Linus says so. In d34cf19b89 (Clean up write_in_full()
     users, 2007-01-11), right after the write_in_full()
     semantics were changed, he wrote:

       I really wish every "write_in_full()" user would just
       check against "<0" now, but this fixes the nasty and
       stupid ones.

     Appeals to authority aside, this makes it clear that
     writing it this way does not have an intentional
     benefit. It's a historical curiosity that we never
     bothered to clean up (and which was undoubtedly
     cargo-culted into new sites).

So let's convert these obviously-correct cases (this
includes write_str_in_full(), which is just a wrapper for
write_in_full()).

[1] A careful reader may notice there is one way that
    write_in_full() can return a different value. If we ask
    write() to write N bytes and get a return value that is
    _larger_ than N, we could return a larger total. But
    besides the fact that this would imply a totally broken
    version of write(), it would already invoke undefined
    behavior. Our internal remaining counter is an unsigned
    size_t, which means that subtracting too many byte will
    wrap it around to a very large number. So we'll instantly
    begin reading off the end of the buffer, trying to write
    gigabytes (or petabytes) of data.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:17:59 +09:00
Jeff King
076aa2cbda tempfile: auto-allocate tempfiles on heap
The previous commit taught the tempfile code to give up
ownership over tempfiles that have been renamed or deleted.
That makes it possible to use a stack variable like this:

  struct tempfile t;

  create_tempfile(&t, ...);
  ...
  if (!err)
          rename_tempfile(&t, ...);
  else
          delete_tempfile(&t);

But doing it this way has a high potential for creating
memory errors. The tempfile we pass to create_tempfile()
ends up on a global linked list, and it's not safe for it to
go out of scope until we've called one of those two
deactivation functions.

Imagine that we add an early return from the function that
forgets to call delete_tempfile(). With a static or heap
tempfile variable, the worst case is that the tempfile hangs
around until the program exits (and some functions like
setup_shallow_temporary rely on this intentionally, creating
a tempfile and then leaving it for later cleanup).

But with a stack variable as above, this is a serious memory
error: the variable goes out of scope and may be filled with
garbage by the time the tempfile code looks at it.  Let's
see if we can make it harder to get this wrong.

Since many callers need to allocate arbitrary numbers of
tempfiles, we can't rely on static storage as a general
solution. So we need to turn to the heap. We could just ask
all callers to pass us a heap variable, but that puts the
burden on them to call free() at the right time.

Instead, let's have the tempfile code handle the heap
allocation _and_ the deallocation (when the tempfile is
deactivated and removed from the list).

This changes the return value of all of the creation
functions. For the cleanup functions (delete and rename),
we'll add one extra bit of safety: instead of taking a
tempfile pointer, we'll take a pointer-to-pointer and set it
to NULL after freeing the object. This makes it safe to
double-call functions like delete_tempfile(), as the second
call treats the NULL input as a noop. Several callsites
follow this pattern.

The resulting patch does have a fair bit of noise, as each
caller needs to be converted to handle:

  1. Storing a pointer instead of the struct itself.

  2. Passing the pointer instead of taking the struct
     address.

  3. Handling a "struct tempfile *" return instead of a file
     descriptor.

We could play games to make this less noisy. For example, by
defining the tempfile like this:

  struct tempfile {
	struct heap_allocated_part_of_tempfile {
                int fd;
                ...etc
        } *actual_data;
  }

Callers would continue to have a "struct tempfile", and it
would be "active" only when the inner pointer was non-NULL.
But that just makes things more awkward in the long run.
There aren't that many callers, so we can simply bite
the bullet and adjust all of them. And the compiler makes it
easy for us to find them all.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-06 17:19:54 +09:00
Jeff King
49bd0fc222 tempfile: do not delete tempfile on failed close
When close_tempfile() fails, we delete the tempfile and
reset the fields of the tempfile struct. This makes it
easier for callers to return without cleaning up, but it
also makes this common pattern:

  if (close_tempfile(tempfile))
	return error_errno("error closing %s", tempfile->filename.buf);

wrong, because the "filename" field has been reset after the
failed close. And it's not easy to fix, as in many cases we
don't have another copy of the filename (e.g., if it was
created via one of the mks_tempfile functions, and we just
have the original template string).

Let's drop the feature that a failed close automatically
deletes the file. This puts the burden on the caller to do
the deletion themselves, but this isn't that big a deal.
Callers which do:

  if (write(...) || close_tempfile(...)) {
	delete_tempfile(...);
	return -1;
  }

already had to call delete when the write() failed, and so
aren't affected. Likewise, any caller which just calls die()
in the error path is OK; we'll delete the tempfile during
the atexit handler.

Because this patch changes the semantics of close_tempfile()
without changing its signature, all callers need to be
manually checked and converted to the new scheme. This patch
covers all in-tree callers, but there may be others for
not-yet-merged topics. To catch these, we rename the
function to close_tempfile_gently(), which will attract
compile-time attention to new callers. (Technically the
original could be considered "gentle" already in that it
didn't die() on errors, but this one is even more so).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-06 17:19:53 +09:00
Jeff King
45c6b1ed24 always check return value of close_tempfile
If close_tempfile() encounters an error, then it deletes the
tempfile and resets the "struct tempfile". But many code
paths ignore the return value and continue to use the
tempfile. Instead, we should generally treat this the same
as a write() error.

Note that in the postimage of some of these cases our error
message will be bogus after a failed close because we look
at tempfile->filename (either directly or via get_tempfile_path).
But after the failed close resets the tempfile object, this
is guaranteed to be the empty string. That will be addressed
in a future patch (because there are many more cases of the
same problem than just these instances).

Note also in the hunk in gpg-interface.c that it's fine to
call delete_tempfile() in the error path, even if
close_tempfile() failed and already deleted the file. The
tempfile code is smart enough to know the second deletion is
a noop.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-06 17:19:53 +09:00
Jeff King
c0e963b77c setup_temporary_shallow: move tempfile struct into function
The setup_temporary_shallow() function creates a temporary
file, but we never access the tempfile struct outside of the
function. This is OK, since it means we'll just clean up the
tempfile on exit.  But we can simplify the code a bit by
moving the global tempfile struct to the only function in
which it's used.

Note that it must remain "static" due to tempfile.c's
requirement that tempfile storage never goes away until
program exit.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-06 17:19:52 +09:00
Jeff King
0899013993 setup_temporary_shallow: avoid using inactive tempfile
When there are no shallow entries to write, we skip creating
the tempfile entirely and try to return the empty string.

But we do so by calling get_tempfile_path() on the inactive
tempfile object. This will trigger an assertion that kills
the program. The bug was introduced by 6e122b449b
(setup_temporary_shallow(): use tempfile module,
2015-08-10). But nobody seems to have noticed since then
because we do not end up calling this function at all when
there are no shallow items. In other words, this code path
is completely unexercised.

Since the tempfile object is a static global, it _is_
possible that we call the function twice, writing out
shallow info the first time and then "reusing" our tempfile
object the second time. But:

  1. It seems unlikely that this was the intent, as hitting
     this code path would imply somebody clearing the
     shallow_info list between calls.

     And if somebody _did_ call the function multiple times
     without clearing the shallow_info list, we'd hit a
     different BUG for trying to reuse an already-active
     tempfile.

  2. I verified by code inspection that the function is only
     called once per program. And also replacing this code
     with a BUG() and running the test suite demonstrates
     that it is not triggered there.

So we could probably just replace this with an assertion and
confirm that it's never called. However, the original intent
does seem to be that you _could_ call it when the
shallow_info is empty. And that's easy enough to do; since
the return value doesn't need to point to a writable buffer,
we can just return a string literal.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-06 17:19:52 +09:00
Stefan Beller
8b65a34c4a commit: convert lookup_commit_graft to struct object_id
With this patch, commit.h doesn't contain the string 'sha1' any more.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-07-13 12:02:40 -07:00
Junio C Hamano
f056cde60e Merge branch 'rs/use-div-round-up'
Code cleanup.

* rs/use-div-round-up:
  use DIV_ROUND_UP
2017-07-12 15:18:23 -07:00
René Scharfe
42c78a216e use DIV_ROUND_UP
Convert code that divides and rounds up to use DIV_ROUND_UP to make the
intent clearer and reduce the number of magic constants.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-07-10 14:24:36 -07:00
Junio C Hamano
849e671b52 Merge branch 'js/plug-leaks'
Fix memory leaks pointed out by Coverity (and people).

* js/plug-leaks: (26 commits)
  checkout: fix memory leak
  submodule_uses_worktrees(): plug memory leak
  show_worktree(): plug memory leak
  name-rev: avoid leaking memory in the `deref` case
  remote: plug memory leak in match_explicit()
  add_reflog_for_walk: avoid memory leak
  shallow: avoid memory leak
  line-log: avoid memory leak
  receive-pack: plug memory leak in update()
  fast-export: avoid leaking memory in handle_tag()
  mktree: plug memory leaks reported by Coverity
  pack-redundant: plug memory leak
  setup_discovered_git_dir(): plug memory leak
  setup_bare_git_dir(): help static analysis
  split_commit_in_progress(): simplify & fix memory leak
  checkout: fix memory leak
  cat-file: fix memory leak
  mailinfo & mailsplit: check for EOF while parsing
  status: close file descriptor after reading git-rebase-todo
  difftool: address a couple of resource/memory leaks
  ...
2017-05-29 12:34:44 +09:00
brian m. carlson
bc83266abe Convert lookup_commit* to struct object_id
Convert lookup_commit, lookup_commit_or_die,
lookup_commit_reference, and lookup_commit_reference_gently to take
struct object_id arguments.

Introduce a temporary in parse_object buffer in order to convert this
function.  This is required since in order to convert parse_object and
parse_object_buffer, lookup_commit_reference_gently and
lookup_commit_or_die would need to be converted.  Not introducing a
temporary would therefore require that lookup_commit_or_die take a
struct object_id *, but lookup_commit would take unsigned char *,
leaving a confusing and hard-to-use interface.

parse_object_buffer will lose this temporary in a later patch.

This commit was created with manual changes to commit.c, commit.h, and
object.c, plus the following semantic patch:

@@
expression E1, E2;
@@
- lookup_commit_reference_gently(E1.hash, E2)
+ lookup_commit_reference_gently(&E1, E2)

@@
expression E1, E2;
@@
- lookup_commit_reference_gently(E1->hash, E2)
+ lookup_commit_reference_gently(E1, E2)

@@
expression E1;
@@
- lookup_commit_reference(E1.hash)
+ lookup_commit_reference(&E1)

@@
expression E1;
@@
- lookup_commit_reference(E1->hash)
+ lookup_commit_reference(E1)

@@
expression E1;
@@
- lookup_commit(E1.hash)
+ lookup_commit(&E1)

@@
expression E1;
@@
- lookup_commit(E1->hash)
+ lookup_commit(E1)

@@
expression E1, E2;
@@
- lookup_commit_or_die(E1.hash, E2)
+ lookup_commit_or_die(&E1, E2)

@@
expression E1, E2;
@@
- lookup_commit_or_die(E1->hash, E2)
+ lookup_commit_or_die(E1, E2)

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-08 15:12:57 +09:00
brian m. carlson
1e43ed9867 Convert remaining callers of lookup_commit_reference* to object_id
There are a small number of remaining callers of lookup_commit_reference
and lookup_commit_reference_gently that still need to be converted to
struct object_id.  Convert these.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-08 15:12:57 +09:00
brian m. carlson
e92b848cb6 shallow: convert shallow registration functions to object_id
Convert register_shallow and unregister_shallow to take struct
object_id.  register_shallow is a caller of lookup_commit, which we will
convert later.  It doesn't make sense for the registration and
unregistration functions to have incompatible interfaces, so convert
them both.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-08 15:12:57 +09:00
Johannes Schindelin
7c565a6b2d shallow: avoid memory leak
Reported by Coverity.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-08 12:18:20 +09:00
brian m. carlson
910650d2f8 Rename sha1_array to oid_array
Since this structure handles an array of object IDs, rename it to struct
oid_array.  Also rename the accessor functions and the initialization
constant.

This commit was produced mechanically by providing non-Documentation
files to the following Perl one-liners:

    perl -pi -E 's/struct sha1_array/struct oid_array/g'
    perl -pi -E 's/\bsha1_array_/oid_array_/g'
    perl -pi -E 's/SHA1_ARRAY_INIT/OID_ARRAY_INIT/g'

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-03-31 08:33:56 -07:00
brian m. carlson
ee3051bd23 sha1-array: convert internal storage for struct sha1_array to object_id
Make the internal storage for struct sha1_array use an array of struct
object_id internally.  Update the users of this struct which inspect its
internals.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-03-28 09:59:34 -07:00
Junio C Hamano
3c9979be9b Merge branch 'nd/shallow-fixup'
Code cleanup in shallow boundary computation.

* nd/shallow-fixup:
  shallow.c: remove useless code
  shallow.c: bit manipulation tweaks
  shallow.c: avoid theoretical pointer wrap-around
  shallow.c: make paint_alloc slightly more robust
  shallow.c: stop abusing COMMIT_SLAB_SIZE for paint_info's memory pools
  shallow.c: rename fields in paint_info to better express their purposes
2016-12-21 14:55:02 -08:00
Nguyễn Thái Ngọc Duy
649b0c316a shallow.c: remove useless code
Some context before we talk about the removed code.

This paint_down() is part of step 6 of 58babff (shallow.c: the 8 steps
to select new commits for .git/shallow - 2013-12-05). When we fetch from
a shallow repository, we need to know if one of the new/updated refs
needs new "shallow commits" in .git/shallow (because we don't have
enough history of those refs) and which one.

The question at step 6 is, what (new) shallow commits are required in
other to maintain reachability throughout the repository _without_
cutting our history short? To answer, we mark all commits reachable from
existing refs with UNINTERESTING ("rev-list --not --all"), mark shallow
commits with BOTTOM, then for each new/updated refs, walk through the
commit graph until we either hit UNINTERESTING or BOTTOM, marking the
ref on the commit as we walk.

After all the walking is done, we check the new shallow commits. If we
have not seen any new ref marked on a new shallow commit, we know all
new/updated refs are reachable using just our history and .git/shallow.
The shallow commit in question is not needed and can be thrown away.

So, the code.

The loop here (to walk through commits) is basically

1.  get one commit from the queue
2.  ignore if it's SEEN or UNINTERESTING
3.  mark it
4.  go through all the parents and..
5a. mark it if it's never marked before
5b. put it back in the queue

What we do in this patch is drop step 5a because it is not
necessary. The commit being marked at 5a is put back on the queue, and
will be marked at step 3 at the next iteration. The only case it will
not be marked is when the commit is already marked UNINTERESTING (5a
does not check this), which will be ignored at step 2.

But we don't care about refs marking on UNINTERESTING. We care about the
marking on _shallow commits_ that are not reachable from our current
history (and having UNINTERESTING on it means it's reachable). So it's
ok for an UNINTERESTING not to be ref-marked.

Reported-by: Rasmus Villemoes <rv@rasmusvillemoes.dk>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-12-07 15:44:31 -08:00
Rasmus Villemoes
1127b3ced5 shallow.c: bit manipulation tweaks
First of all, 1 << 31 is technically undefined behaviour, so let's just
use an unsigned literal.

If i is 'signed int' and gcc doesn't know that i is positive, gcc
generates code to compute the C99-mandated values of "i / 32" and "i %
32", which is a lot more complicated than simple a simple shifts/mask.

The only caller of paint_down actually passes an "unsigned int" value,
but the prototype of paint_down causes (completely well-defined)
conversion to signed int, and gcc has no way of knowing that the
converted value is non-negative. Just make the id parameter unsigned.

In update_refstatus, the change in generated code is much smaller,
presumably because gcc is smart enough to see that i starts as 0 and is
only incremented, so it is allowed (per the UD of signed overflow) to
assume that i is always non-negative. But let's just help less smart
compilers generate good code anyway.

Signed-off-by: Rasmus Villemoes <rv@rasmusvillemoes.dk>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-12-07 15:44:31 -08:00
Rasmus Villemoes
381aa8e730 shallow.c: avoid theoretical pointer wrap-around
The expression info->free+size is technically undefined behaviour in
exactly the case we want to test for. Moreover, the compiler is likely
to translate the expression to

  (unsigned long)info->free + size > (unsigned long)info->end

where there's at least a theoretical chance that the LHS could wrap
around 0, giving a false negative.

This might as well be written using pointer subtraction avoiding these
issues.

Signed-off-by: Rasmus Villemoes <rv@rasmusvillemoes.dk>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-12-07 15:44:31 -08:00
Nguyễn Thái Ngọc Duy
f2386c6b77 shallow.c: make paint_alloc slightly more robust
paint_alloc() allocates a big block of memory and splits it into
smaller, fixed size, chunks of memory whenever it's called. Each chunk
contains enough bits to present all "new refs" [1] in a fetch from a
shallow repository.

We do not check if the new "big block" is smaller than the requested
memory chunk though. If it happens, we'll happily pass back a memory
region smaller than expected. Which will lead to problems eventually.

A normal fetch may add/update a dozen new refs. Let's stay on the
"reasonably extreme" side and say we need 16k refs (or bits from
paint_alloc's perspective). Each chunk of memory would be 2k, much
smaller than the memory pool (512k).

So, normally, the under-allocation situation should never happen. A bad
guy, however, could make a fetch that adds more than 4m new/updated refs
to this code which results in a memory chunk larger than pool size.
Check this case and abort.

Noticed-by: Rasmus Villemoes <rv@rasmusvillemoes.dk>
Reviewed-by: Jeff King <peff@peff.net>

[1] Details are in commit message of 58babff (shallow.c: the 8 steps to
    select new commits for .git/shallow - 2013-12-05), step 6.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-12-07 15:44:31 -08:00
Nguyễn Thái Ngọc Duy
6bc3d8c5ec shallow.c: stop abusing COMMIT_SLAB_SIZE for paint_info's memory pools
We need to allocate a "big" block of memory in paint_alloc(). The exact
size does not really matter. But the pool size has no relation with
commit-slab. Stop using that macro here.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-12-07 15:44:31 -08:00
Nguyễn Thái Ngọc Duy
0afd307ab4 shallow.c: rename fields in paint_info to better express their purposes
paint_alloc() is basically malloc(), tuned for allocating a fixed number
of bits on every call without worrying about freeing any individual
allocation since all will be freed at the end. It does it by allocating
a big block of memory every time it runs out of "free memory". "slab" is
a poor choice of name, at least poorer than "pool".

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-12-07 15:44:31 -08:00
Junio C Hamano
dbaa6bdce2 Merge branch 'ls/filter-process'
The smudge/clean filter API expect an external process is spawned
to filter the contents for each path that has a filter defined.  A
new type of "process" filter API has been added to allow the first
request to run the filter for a path to spawn a single process, and
all filtering need is served by this single process for multiple
paths, reducing the process creation overhead.

* ls/filter-process:
  contrib/long-running-filter: add long running filter example
  convert: add filter.<driver>.process option
  convert: prepare filter.<driver>.process option
  convert: make apply_filter() adhere to standard Git error handling
  pkt-line: add functions to read/write flush terminated packet streams
  pkt-line: add packet_write_gently()
  pkt-line: add packet_flush_gently()
  pkt-line: add packet_write_fmt_gently()
  pkt-line: extract set_packet_header()
  pkt-line: rename packet_write() to packet_write_fmt()
  run-command: add clean_on_exit_handler
  run-command: move check_pipe() from write_or_die to run_command
  convert: modernize tests
  convert: quote filter names in error messages
2016-10-31 13:15:21 -07:00
Lars Schneider
81c634e94f pkt-line: rename packet_write() to packet_write_fmt()
packet_write() should be called packet_write_fmt() because it is a
printf-like function that takes a format string as first parameter.

packet_write_fmt() should be used for text strings only. Arbitrary
binary data should use a new packet_write() function that is introduced
in a subsequent patch.

Suggested-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-10-17 11:36:50 -07:00
Junio C Hamano
a460ea4a3c Merge branch 'nd/shallow-deepen'
The existing "git fetch --depth=<n>" option was hard to use
correctly when making the history of an existing shallow clone
deeper.  A new option, "--deepen=<n>", has been added to make this
easier to use.  "git clone" also learned "--shallow-since=<date>"
and "--shallow-exclude=<tag>" options to make it easier to specify
"I am interested only in the recent N months worth of history" and
"Give me only the history since that version".

* nd/shallow-deepen: (27 commits)
  fetch, upload-pack: --deepen=N extends shallow boundary by N commits
  upload-pack: add get_reachable_list()
  upload-pack: split check_unreachable() in two, prep for get_reachable_list()
  t5500, t5539: tests for shallow depth excluding a ref
  clone: define shallow clone boundary with --shallow-exclude
  fetch: define shallow boundary with --shallow-exclude
  upload-pack: support define shallow boundary by excluding revisions
  refs: add expand_ref()
  t5500, t5539: tests for shallow depth since a specific date
  clone: define shallow clone boundary based on time with --shallow-since
  fetch: define shallow boundary with --shallow-since
  upload-pack: add deepen-since to cut shallow repos based on time
  shallow.c: implement a generic shallow boundary finder based on rev-list
  fetch-pack: use a separate flag for fetch in deepening mode
  fetch-pack.c: mark strings for translating
  fetch-pack: use a common function for verbose printing
  fetch-pack: use skip_prefix() instead of starts_with()
  upload-pack: move rev-list code out of check_non_tip()
  upload-pack: make check_non_tip() clean things up on error
  upload-pack: tighten number parsing at "deepen" lines
  ...
2016-10-10 14:03:50 -07:00
René Scharfe
50492f7b38 pass constants as first argument to st_mult()
The result of st_mult() is the same no matter the order of its
arguments.  It invokes the macro unsigned_mult_overflows(), which
divides the second parameter by the first one.  Pass constants
first to allow that division to be done already at compile time.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-01 14:01:03 -07:00
Nguyễn Thái Ngọc Duy
3d9ff4d736 shallow.c: implement a generic shallow boundary finder based on rev-list
Instead of a custom commit walker like get_shallow_commits(), this new
function uses rev-list to mark NOT_SHALLOW to all reachable commits,
except borders. The definition of reachable is to be defined by the
protocol later. This makes it more flexible to define shallow boundary.

The way we find border is paint all reachable commits NOT_SHALLOW.  Any
of them that "touches" commits without NOT_SHALLOW flag are considered
shallow (e.g. zero parents via grafting mechanism). Shallow commits and
their true parents are all marked SHALLOW. Then NOT_SHALLOW is removed
from shallow commits at the end.

There is an interesting observation. With a generic walker, we can
produce all kinds of shallow cutting. In the following graph, every
commit but "x" is reachable. "b" is a parent of "a".

           x -- a -- o
          /    /
    x -- c -- b -- o

After this function is run, "a" and "c" are both considered shallow
commits. After grafting occurs at the client side, what we see is

                a -- o
                    /
         c -- b -- o

Notice that because of grafting, "a" has zero parents, so "b" is no
longer a parent of "a".

This is unfortunate and may be solved in two ways. The first is change
the way shallow grafting works and keep "a -- b" connection if "b"
exists and always ends at shallow commits (iow, no loose ends). This is
hard to detect, or at least not cheap to do.

The second way is mark one "x" as shallow commit instead of "a" and
produce this graph at client side:

           x -- a -- o
               /    /
         c -- b -- o

More commits, but simpler grafting rules.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-13 14:38:16 -07:00
Jeff King
50a6c8efa2 use st_add and st_mult for allocation size computation
If our size computation overflows size_t, we may allocate a
much smaller buffer than we expected and overflow it. It's
probably impossible to trigger an overflow in most of these
sites in practice, but it is easy enough convert their
additions and multiplications into overflow-checking
variants. This may be fixing real bugs, and it makes
auditing the code easier.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-02-22 14:51:09 -08:00
Jeff King
b32fa95fd8 convert trivial cases to ALLOC_ARRAY
Each of these cases can be converted to use ALLOC_ARRAY or
REALLOC_ARRAY, which has two advantages:

  1. It automatically checks the array-size multiplication
     for overflow.

  2. It always uses sizeof(*array) for the element-size,
     so that it can never go out of sync with the declared
     type of the array.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-02-22 14:51:09 -08:00
brian m. carlson
ed1c9977cb Remove get_object_hash.
Convert all instances of get_object_hash to use an appropriate reference
to the hash member of the oid member of struct object.  This provides no
functional change, as it is essentially a macro substitution.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Jeff King <peff@peff.net>
2015-11-20 08:02:05 -05:00
brian m. carlson
f2fd0760f6 Convert struct object to object_id
struct object is one of the major data structures dealing with object
IDs.  Convert it to use struct object_id instead of an unsigned char
array.  Convert get_object_hash to refer to the new member as well.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Jeff King <peff@peff.net>
2015-11-20 08:02:05 -05:00
brian m. carlson
7999b2cf77 Add several uses of get_object_hash.
Convert most instances where the sha1 member of struct object is
dereferenced to use get_object_hash.  Most instances that are passed to
functions that have versions taking struct object_id, such as
get_sha1_hex/get_oid_hex, or instances that can be trivially converted
to use struct object_id instead, are not converted.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Jeff King <peff@peff.net>
2015-11-20 08:02:05 -05:00
Junio C Hamano
0692a6c22c Merge branch 'rs/pop-commit'
Code simplification.

* rs/pop-commit:
  use pop_commit() for consuming the first entry of a struct commit_list
2015-10-30 13:07:03 -07:00
Junio C Hamano
433cc7e3fb Merge branch 'tk/sigchain-unnecessary-post-tempfile'
Remove no-longer used #include.

* tk/sigchain-unnecessary-post-tempfile:
  shallow: remove unused #include "sigchain.h"
  read-cache: remove unused #include "sigchain.h"
  diff: remove unused #include "sigchain.h"
  credential-cache--daemon: remove unused #include "sigchain.h"
2015-10-29 13:59:18 -07:00
René Scharfe
e510ab8988 use pop_commit() for consuming the first entry of a struct commit_list
Instead of open-coding the function pop_commit() just call it.  This
makes the intent clearer and reduces code size.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-10-26 14:06:46 -07:00
Tobias Klauser
4b7c50a184 shallow: remove unused #include "sigchain.h"
After switching to use the tempfile module in commit 6e122b44
(setup_temporary_shallow(): use tempfile module), no declarations from
sigchain.h are used in read-cache.c anymore. Thus, remove the #include.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-10-22 11:12:38 -07:00
Junio C Hamano
db86e61cbb Merge branch 'mh/tempfile'
The "lockfile" API has been rebuilt on top of a new "tempfile" API.

* mh/tempfile:
  credential-cache--daemon: use tempfile module
  credential-cache--daemon: delete socket from main()
  gc: use tempfile module to handle gc.pid file
  lock_repo_for_gc(): compute the path to "gc.pid" only once
  diff: use tempfile module
  setup_temporary_shallow(): use tempfile module
  write_shared_index(): use tempfile module
  register_tempfile(): new function to handle an existing temporary file
  tempfile: add several functions for creating temporary files
  prepare_tempfile_object(): new function, extracted from create_tempfile()
  tempfile: a new module for handling temporary files
  commit_lock_file(): use get_locked_file_path()
  lockfile: add accessor get_lock_file_path()
  lockfile: add accessors get_lock_file_fd() and get_lock_file_fp()
  create_bundle(): duplicate file descriptor to avoid closing it twice
  lockfile: move documentation to lockfile.h and lockfile.c
2015-08-25 14:57:09 -07:00
Jeff King
f932729cc7 memoize common git-path "constant" files
One of the most common uses of git_path() is to pass a
constant, like git_path("MERGE_MSG"). This has two
drawbacks:

  1. The return value is a static buffer, and the lifetime
     is dependent on other calls to git_path, etc.

  2. There's no compile-time checking of the pathname. This
     is OK for a one-off (after all, we have to spell it
     correctly at least once), but many of these constant
     strings appear throughout the code.

This patch introduces a series of functions to "memoize"
these strings, which are essentially globals for the
lifetime of the program. We compute the value once, take
ownership of the buffer, and return the cached value for
subsequent calls.  cache.h provides a helper macro for
defining these functions as one-liners, and defines a few
common ones for global use.

Using a macro is a little bit gross, but it does nicely
document the purpose of the functions. If we need to touch
them all later (e.g., because we learned how to change the
git_dir variable at runtime, and need to invalidate all of
the stored values), it will be much easier to have the
complete list.

Note that the shared-global functions have separate, manual
declarations. We could do something clever with the macros
(e.g., expand it to a declaration in some places, and a
declaration _and_ a definition in path.c). But there aren't
that many, and it's probably better to stay away from
too-magical macros.

Likewise, if we abandon the C preprocessor in favor of
generating these with a script, we could get much fancier.
E.g., normalizing "FOO/BAR-BAZ" into "git_path_foo_bar_baz".
But the small amount of saved typing is probably not worth
the resulting confusion to readers who want to grep for the
function's definition.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-10 15:37:14 -07:00
Michael Haggerty
6e122b449b setup_temporary_shallow(): use tempfile module
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-10 12:57:14 -07:00