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Author SHA1 Message Date
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
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
Michael Haggerty
b4fb09e4da lockfile: add accessor get_lock_file_path()
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
Michael Haggerty
580b04ef98 shallow: rewrite functions to take object_id arguments
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-25 12:19:36 -07:00
Michael Haggerty
2b2a5be394 each_ref_fn: change to take an object_id parameter
Change typedef each_ref_fn to take a "const struct object_id *oid"
parameter instead of "const unsigned char *sha1".

To aid this transition, implement an adapter that can be used to wrap
old-style functions matching the old typedef, which is now called
"each_ref_sha1_fn"), and make such functions callable via the new
interface. This requires the old function and its cb_data to be
wrapped in a "struct each_ref_fn_sha1_adapter", and that object to be
used as the cb_data for an adapter function, each_ref_fn_adapter().

This is an enormous diff, but most of it consists of simple,
mechanical changes to the sites that call any of the "for_each_ref"
family of functions. Subsequent to this change, the call sites can be
rewritten one by one to use the new interface.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-25 12:19:27 -07:00
Junio C Hamano
a916cb5fb4 Merge branch 'bc/object-id'
Identify parts of the code that knows that we use SHA-1 hash to
name our objects too much, and use (1) symbolic constants instead
of hardcoded 20 as byte count and/or (2) use struct object_id
instead of unsigned char [20] for object names.

* bc/object-id:
  apply: convert threeway_stage to object_id
  patch-id: convert to use struct object_id
  commit: convert parts to struct object_id
  diff: convert struct combine_diff_path to object_id
  bulk-checkin.c: convert to use struct object_id
  zip: use GIT_SHA1_HEXSZ for trailers
  archive.c: convert to use struct object_id
  bisect.c: convert leaf functions to use struct object_id
  define utility functions for object IDs
  define a structure for object IDs
2015-05-05 21:00:23 -07:00
brian m. carlson
7683e2e6e3 commit: convert parts to struct object_id
Convert struct commit_graft and necessary local parts of commit.c.
Also, convert several constants based on the hex length of an SHA-1 to
use GIT_SHA1_HEXSZ, and move several magic constants into variables for
readability.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-03-13 22:43:13 -07:00
Junio C Hamano
faf723a631 Merge branch 'jk/blame-commit-label' into maint
"git blame HEAD -- missing" failed to correctly say "HEAD" when it
tried to say "No such path 'missing' in HEAD".

* jk/blame-commit-label:
  blame.c: fix garbled error message
  use xstrdup_or_null to replace ternary conditionals
  builtin/commit.c: use xstrdup_or_null instead of envdup
  builtin/apply.c: use xstrdup_or_null instead of null_strdup
  git-compat-util: add xstrdup_or_null helper
2015-02-24 22:09:54 -08:00
Junio C Hamano
c985aaf879 Merge branch 'jc/unused-symbols'
Mark file-local symbols as "static", and drop functions that nobody
uses.

* jc/unused-symbols:
  shallow.c: make check_shallow_file_for_update() static
  remote.c: make clear_cas_option() static
  urlmatch.c: make match_urls() static
  revision.c: make save_parents() and free_saved_parents() static
  line-log.c: make line_log_data_init() static
  pack-bitmap.c: make pack_bitmap_filename() static
  prompt.c: remove git_getpass() nobody uses
  http.c: make finish_active_slot() and handle_curl_result() static
2015-02-11 13:44:07 -08:00
Junio C Hamano
092c4be7f5 Merge branch 'jk/blame-commit-label'
"git blame HEAD -- missing" failed to correctly say "HEAD" when it
tried to say "No such path 'missing' in HEAD".

* jk/blame-commit-label:
  blame.c: fix garbled error message
  use xstrdup_or_null to replace ternary conditionals
  builtin/commit.c: use xstrdup_or_null instead of envdup
  builtin/apply.c: use xstrdup_or_null instead of null_strdup
  git-compat-util: add xstrdup_or_null helper
2015-02-11 13:39:50 -08:00
Junio C Hamano
167832c2ca shallow.c: make check_shallow_file_for_update() static
No external callers exist.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-01-15 11:05:48 -08:00
Jeff King
8c53f0719b use xstrdup_or_null to replace ternary conditionals
This replaces "x ? xstrdup(x) : NULL" with xstrdup_or_null(x).
The change is fairly mechanical, with the exception of
resolve_refdup, which can eliminate a temporary variable.

There are still a few hits grepping for "?.*xstrdup", but
these are of slightly different forms and cannot be
converted (e.g., "x ? xstrdup(x->foo) : NULL").

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-01-13 10:05:48 -08:00
Junio C Hamano
e4da4fbe0e Merge branch 'eb/no-pthreads'
Allow us build with NO_PTHREADS=NoThanks compilation option.

* eb/no-pthreads:
  Handle atexit list internaly for unthreaded builds
  pack-objects: set number of threads before checking and warning
  index-pack: fix compilation with NO_PTHREADS
2014-10-24 14:59:10 -07:00
Etienne Buira
0f4b6db3ba Handle atexit list internaly for unthreaded builds
Wrap atexit()s calls on unthreaded builds to handle callback list
internally.

This is needed because on unthreaded builds, asyncs inherits parent's
atexit() list, that gets run as soon as the async exit()s (and again at
the end of async's parent process). That led to remove temporary files
too early.

Also remove a by-atexit-callback guard against this kind of issue in
clone.c, as this patch makes it redundant.

Fixes test 5537 (temporary shallow file vanished before unpack-objects
could open it)

BTW remove an unused variable in shallow.c.

Helped-by: Duy Nguyen <pclouds@gmail.com>
Helped-by: Andreas Schwab <schwab@linux-m68k.org>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Etienne Buira <etienne.buira@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-10-19 15:38:30 -07:00
Michael Haggerty
697cc8efd9 lockfile.h: extract new header file for the functions in lockfile.c
Move the interface declaration for the functions in lockfile.c from
cache.h to a new file, lockfile.h. Add #includes where necessary (and
remove some redundant includes of cache.h by files that already
include builtin.h).

Move the documentation of the lock_file state diagram from lockfile.c
to the new header file.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-10-01 13:56:14 -07:00
Michael Haggerty
cf6950d3bf 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>
2014-10-01 13:50:01 -07:00
René Scharfe
2756ca4347 use REALLOC_ARRAY for changing the allocation size of arrays
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-09-18 09:13:42 -07:00
Karsten Blees
6aa3085702 trace: improve trace performance
The trace API currently rechecks the environment variable and reopens the
trace file on every API call. This has the ugly side effect that errors
(e.g. file cannot be opened, or the user specified a relative path) are
also reported on every call. Performance can be improved by about factor
three by remembering the environment state and keeping the file open.

Replace the 'const char *key' parameter in the API with a pointer to a
'struct trace_key' that bundles the environment variable name with
additional, trace-internal state. Change the call sites of these APIs to
use a static 'struct trace_key' instead of a string constant.

In trace.c::get_trace_fd(), save and reuse the file descriptor in 'struct
trace_key'.

Add a 'trace_disable()' API, so that packet_trace() can cleanly disable
tracing when it encounters packed data (instead of using unsetenv()).

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-07-13 21:24:23 -07:00
Jeff King
7839632167 shallow: verify shallow file after taking lock
Before writing the shallow file, we stat() the existing file
to make sure it has not been updated since our operation
began. However, we do not do so under a lock, so there is a
possible race:

  1. Process A takes the lock.

  2. Process B calls check_shallow_file_for_update and finds
     no update.

  3. Process A commits the lockfile.

  4. Process B takes the lock, then overwrite's process A's
     changes.

We can fix this by doing our check while we hold the lock.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-03-17 15:03:32 -07:00
Jeff King
0179c945fc shallow: automatically clean up shallow tempfiles
We sometimes write tempfiles of the form "shallow_XXXXXX"
during fetch/push operations with shallow repositories.
Under normal circumstances, we clean up the result when we
are done. However, we do no take steps to clean up after
ourselves when we exit due to die() or signal death.

This patch teaches the tempfile creation code to register
handlers to clean up after ourselves. To handle this, we
change the ownership semantics of the filename returned by
setup_temporary_shallow. It now keeps a copy of the filename
itself, and returns only a const pointer to it.

We can also do away with explicit tempfile removal in the
callers. They all exit not long after finishing with the
file, so they can rely on the auto-cleanup, simplifying the
code.

Note that we keep things simple and maintain only a single
filename to be cleaned. This is sufficient for the current
caller, but we future-proof it with a die("BUG").

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-02-27 12:07:13 -08:00
Jeff King
0cc77c386c shallow: use stat_validity to check for up-to-date file
When we are about to write the shallow file, we check that
it has not changed since we last read it. Instead of
hand-rolling this, we can use stat_validity. This is built
around the index stat-check, so it is more robust than just
checking the mtime, as we do now (it uses the same check as
we do for index files).

The new code also handles the case of a shallow file
appearing unexpectedly. With the current code, two
simultaneous processes making us shallow (e.g., two "git
fetch --depth=1" running at the same time in a non-shallow
repository) can race to overwrite each other.

As a bonus, we also remove a race in determining the stat
information of what we read (we stat and then open, leaving
a race window; instead we should open and then fstat the
descriptor).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-02-27 12:04:23 -08:00
Junio C Hamano
92251b1b5b Merge branch 'nd/shallow-clone'
Fetching from a shallow-cloned repository used to be forbidden,
primarily because the codepaths involved were not carefully vetted
and we did not bother supporting such usage. This attempts to allow
object transfer out of a shallow-cloned repository in a controlled
way (i.e. the receiver become a shallow repository with truncated
history).

* nd/shallow-clone: (31 commits)
  t5537: fix incorrect expectation in test case 10
  shallow: remove unused code
  send-pack.c: mark a file-local function static
  git-clone.txt: remove shallow clone limitations
  prune: clean .git/shallow after pruning objects
  clone: use git protocol for cloning shallow repo locally
  send-pack: support pushing from a shallow clone via http
  receive-pack: support pushing to a shallow clone via http
  smart-http: support shallow fetch/clone
  remote-curl: pass ref SHA-1 to fetch-pack as well
  send-pack: support pushing to a shallow clone
  receive-pack: allow pushes that update .git/shallow
  connected.c: add new variant that runs with --shallow-file
  add GIT_SHALLOW_FILE to propagate --shallow-file to subprocesses
  receive/send-pack: support pushing from a shallow clone
  receive-pack: reorder some code in unpack()
  fetch: add --update-shallow to accept refs that update .git/shallow
  upload-pack: make sure deepening preserves shallow roots
  fetch: support fetching from a shallow repository
  clone: support remote shallow repository
  ...
2014-01-17 12:21:20 -08:00
Ramsay Jones
feefdf62c1 shallow: remove unused code
Commit 58babfff ("shallow.c: the 8 steps to select new commits for
.git/shallow", 05-12-2013) added a function to implement step 5 of
the quoted eight steps, namely 'remove_nonexistent_ours_in_pack()'.
This function implements an optional optimization step in the new
shallow commit selection algorithm. However, this function has no
callers. (The commented out call sites would need to change, in
order to provide information required by the function.)

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Acked-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-01-06 09:05:40 -08:00
Nguyễn Thái Ngọc Duy
eab3296c7e prune: clean .git/shallow after pruning objects
This patch teaches "prune" to remove shallow roots that are no longer
reachable from any refs (e.g. when the relevant refs are removed).

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-12-10 16:14:19 -08:00
Nguyễn Thái Ngọc Duy
0a1bc12b6e receive-pack: allow pushes that update .git/shallow
The basic 8 steps to update .git/shallow does not fully apply here
because the user may choose to accept just a few refs (while fetch
always accepts all refs). The steps are modified a bit.

1-6. same as before. After calling assign_shallow_commits_to_refs at
   step 6, each shallow commit has a bitmap that marks all refs that
   require it.

7. mark all "ours" shallow commits that are reachable from any
   refs. We will need to do the original step 7 on them later.

8. go over all shallow commit bitmaps, mark refs that require new
   shallow commits.

9. setup a strict temporary shallow file to plug all the holes, even
   if it may cut some of our history short. This file is used by all
   hooks. The hooks could use --shallow-file=$GIT_DIR/shallow to
   overcome this and reach everything in current repo.

10. go over the new refs one by one. For each ref, do the reachability
   test if it needs a shallow commit on the list from step 7. Remove
   it if it's reachable from our refs. Gather all required shallow
   commits, run check_everything_connected() with the new ref, then
   install them to .git/shallow.

This mode is disabled by default and can be turned on with
receive.shallowupdate

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-12-10 16:14:18 -08:00
Nguyễn Thái Ngọc Duy
069c053222 add GIT_SHALLOW_FILE to propagate --shallow-file to subprocesses
This may be needed when a hook is run after a new shallow pack is
received, but .git/shallow is not settled yet. A temporary shallow
file to plug all loose ends should be used instead. GIT_SHALLOW_FILE
is overriden by --shallow-file.

--shallow-file does not work in this case because the hook may spawn
many git subprocesses and the launch commands do not have
--shallow-file as it's a recent addition.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-12-10 16:14:17 -08:00
Nguyễn Thái Ngọc Duy
79d3a236c5 upload-pack: make sure deepening preserves shallow roots
When "fetch --depth=N" where N exceeds the longest chain of history in
the source repo, usually we just send an "unshallow" line to the
client so full history is obtained.

When the source repo is shallow we need to make sure to "unshallow"
the current shallow point _and_ "shallow" again when the commit
reaches its shallow bottom in the source repo.

This should fix both cases: large <N> and --unshallow.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-12-10 16:14:17 -08:00
Nguyễn Thái Ngọc Duy
8e277383e0 shallow.c: steps 6 and 7 to select new commits for .git/shallow
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-12-10 16:14:16 -08:00
Nguyễn Thái Ngọc Duy
58babfffde shallow.c: the 8 steps to select new commits for .git/shallow
Suppose a fetch or push is requested between two shallow repositories
(with no history deepening or shortening). A pack that contains
necessary objects is transferred over together with .git/shallow of
the sender. The receiver has to determine whether it needs to update
.git/shallow if new refs needs new shallow comits.

The rule here is avoid updating .git/shallow by default. But we don't
want to waste the received pack. If the pack contains two refs, one
needs new shallow commits installed in .git/shallow and one does not,
we keep the latter and reject/warn about the former.

Even if .git/shallow update is allowed, we only add shallow commits
strictly necessary for the former ref (remember the sender can send
more shallow commits than necessary) and pay attention not to
accidentally cut the receiver history short (no history shortening is
asked for)

So the steps to figure out what ref need what new shallow commits are:

1. Split the sender shallow commit list into "ours" and "theirs" list
   by has_sha1_file. Those that exist in current repo in "ours", the
   remaining in "theirs".

2. Check the receiver .git/shallow, remove from "ours" the ones that
   also exist in .git/shallow.

3. Fetch the new pack. Either install or unpack it.

4. Do has_sha1_file on "theirs" list again. Drop the ones that fail
   has_sha1_file. Obviously the new pack does not need them.

5. If the pack is kept, remove from "ours" the ones that do not exist
   in the new pack.

6. Walk the new refs to answer the question "what shallow commits,
   both ours and theirs, are required in .git/shallow in order to add
   this ref?". Shallow commits not associated to any refs are removed
   from their respective list.

7. (*) Check reachability (from the current refs) of all remaining
   commits in "ours". Those reachable are removed. We do not want to
   cut any part of our (reachable) history. We only check up
   commits. True reachability test is done by
   check_everything_connected() at the end as usual.

8. Combine the final "ours" and "theirs" and add them all to
   .git/shallow. Install new refs. The case where some hook rejects
   some refs on a push is explained in more detail in the push
   patches.

Of these steps, #6 and #7 are expensive. Both require walking through
some commits, or in the worst case all commits. And we rather avoid
them in at least common case, where the transferred pack does not
contain any shallow commits that the sender advertises. Let's look at
each scenario:

1) the sender has longer history than the receiver

   All shallow commits from the sender will be put into "theirs" list
   at step 1 because none of them exists in current repo. In the
   common case, "theirs" becomes empty at step 4 and exit early.

2) the sender has shorter history than the receiver

   All shallow commits from the sender are likely in "ours" list at
   step 1. In the common case, if the new pack is kept, we could empty
   "ours" and exit early at step 5.

   If the pack is not kept, we hit the expensive step 6 then exit
   after "ours" is emptied. There'll be only a handful of objects to
   walk in fast-forward case. If it's forced update, we may need to
   walk to the bottom.

3) the sender has same .git/shallow as the receiver

   This is similar to case 2 except that "ours" should be emptied at
   step 2 and exit early.

A fetch after "clone --depth=X" is case 1. A fetch after "clone" (from
a shallow repo) is case 3. Luckily they're cheap for the common case.

A push from "clone --depth=X" falls into case 2, which is expensive.
Some more work may be done at the sender/client side to avoid more
work on the server side: if the transferred pack does not contain any
shallow commits, send-pack should not send any shallow commits to the
receive-pack, effectively turning it into a normal push and avoid all
steps.

This patch implements all steps except #3, already handled by
fetch-pack and receive-pack, #6 and #7, which has their own patch due
to their size.

(*) in previous versions step 7 was put before step 3. I reorder it so
    that the common case that keeps the pack does not need to walk
    commits at all. In future if we implement faster commit
    reachability check (maybe with the help of pack bitmaps or commit
    cache), step 7 could become cheap and be moved up before 6 again.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-12-10 16:14:16 -08:00
Nguyễn Thái Ngọc Duy
1a30f5a2f2 shallow.c: extend setup_*_shallow() to accept extra shallow commits
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-12-10 16:14:16 -08:00
Nguyễn Thái Ngọc Duy
ad491366de make the sender advertise shallow commits to the receiver
If either receive-pack or upload-pack is called on a shallow
repository, shallow commits (*) will be sent after the ref
advertisement (but before the packet flush), so that the receiver has
the full "shape" of the sender's commit graph. This will be needed for
the receiver to update its .git/shallow if necessary.

This breaks the protocol for all clients trying to push to a shallow
repo, or fetch from one. Which is basically the same end result as
today's "is_repository_shallow() && die()" in receive-pack and
upload-pack. New clients will be made aware of shallow upstream and
can make use of this information.

The sender must send all shallow commits that are sent in the
following pack. It may send more shallow commits than necessary.

upload-pack for example may choose to advertise no shallow commits if
it knows in advance that the pack it's going to send contains no
shallow commits. But upload-pack is the server, so we choose the
cheaper way, send full .git/shallow and let the client deal with it.

Smart HTTP is not affected by this patch. Shallow support on
smart-http comes later separately.

(*) A shallow commit is a commit that terminates the revision
    walker. It is usually put in .git/shallow in order to keep the
    revision walker from going out of bound because there is no
    guarantee that objects behind this commit is available.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-12-10 16:14:16 -08:00
Junio C Hamano
5bb62059f2 Merge branch 'jk/robustify-parse-commit'
* jk/robustify-parse-commit:
  checkout: do not die when leaving broken detached HEAD
  use parse_commit_or_die instead of custom message
  use parse_commit_or_die instead of segfaulting
  assume parse_commit checks for NULL commit
  assume parse_commit checks commit->object.parsed
  log_tree_diff: die when we fail to parse a commit
2013-12-05 12:54:01 -08:00
Jeff King
367068e0dd use parse_commit_or_die instead of custom message
Many calls to parse_commit detect errors and die. In some
cases, the custom error messages are more useful than what
parse_commit_or_die could produce, because they give some
context, like which ref the commit came from. Some, however,
just say "invalid commit". Let's convert the latter to use
parse_commit_or_die; its message is slightly more informative,
and it makes the error more consistent throughout git.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-10-24 15:43:51 -07:00
Nguyễn Thái Ngọc Duy
08ea65ad13 shallow: add setup_temporary_shallow()
This function is like setup_alternate_shallow() except that it does
not lock $GIT_DIR/shallow.  It is supposed to be used when a program
generates temporary shallow for use by another program, then throw
the shallow file away.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-08-28 11:51:54 -07:00
Nguyễn Thái Ngọc Duy
6a3bbb4db4 shallow: only add shallow graft points to new shallow file
for_each_commit_graft() goes through all graft points, and shallow
boundaries are just one special kind of grafting.

If $GIT_DIR/shallow and $GIT_DIR/info/grafts are both present,
write_shallow_commits() may catch both sets, accidentally turning
some graft points to shallow boundaries.  Don't do that.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-08-28 11:51:17 -07:00
Nguyễn Thái Ngọc Duy
3125fe528b move setup_alternate_shallow and write_shallow_commits to shallow.c
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-08-18 13:00:17 -07:00
Junio C Hamano
4c72ee838f Merge branch 'mk/upload-pack-off-by-one-dead-code-removal'
* mk/upload-pack-off-by-one-dead-code-removal:
  upload-pack: remove a piece of dead code
2013-07-22 11:24:05 -07:00
Matthijs Kooijman
4b796951ff upload-pack: remove a piece of dead code
Commit 682c7d2 (upload-pack: fix off-by-one depth calculation in shallow
clone) introduced a new check in get_shallow_commits to decide when to
stop traversing the history and mark the current commit as a shallow
root.

With this new check in place, the old check can no longer be true, since
the first check always fires first. This commit removes that check,
making the code a bit more simple again.

Signed-off-by: Matthijs Kooijman <matthijs@stdin.nl>
Acked-by: Duy Nguyen <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-07-15 10:49:42 -07:00
Nguyễn Thái Ngọc Duy
6035d6aad8 fetch-pack: prepare updated shallow file before fetching the pack
index-pack --strict looks up and follows parent commits. If shallow
information is not ready by the time index-pack is run, index-pack may
be led to non-existent objects. Make fetch-pack save shallow file to
disk before invoking index-pack.

git learns new global option --shallow-file to pass on the alternate
shallow file path. Undocumented (and not even support --shallow-file=
syntax) because it's unlikely to be used again elsewhere.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-05-28 08:06:08 -07:00