Commit Graph

465 Commits

Author SHA1 Message Date
Junio C Hamano
33481c1e59 Merge branch 'jc/hashmap-doc-init' into maint
The API documentation for hashmap was unclear if hashmap_entry
can be safely discarded without any other consideration.  State
that it is safe to do so.

* jc/hashmap-doc-init:
  hashmap: clarify that hashmap_entry can safely be discarded
2016-08-10 11:55:31 -07:00
Junio C Hamano
593be730f2 Merge branch 'sb/pack-protocol-doc-nak' into maint
A doc update.

* sb/pack-protocol-doc-nak:
  Documentation: pack-protocol correct NAK response
2016-08-08 14:21:47 -07:00
Junio C Hamano
54ba5a1a16 hashmap: clarify that hashmap_entry can safely be discarded
The API documentation said that the hashmap_entry structure to be
embedded in the caller's structure is to be treated as opaque, which
left the reader wondering if it can safely be discarded when it no
longer is necessary.  If the hashmap_entry structure had references
to external resources such as allocated memory or an open file
descriptor, merely free(3)ing the containing structure (when the
caller's structure is on the heap) or letting it go out of scope
(when it is on the stack) would end up leaking the external
resource.

Document that there is no need for hashmap_entry_clear() that
corresponds to hashmap_entry_init() to give the API users a little
bit of peace of mind.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-02 14:34:17 -07:00
Stefan Beller
280abfd4f5 Documentation: pack-protocol correct NAK response
In the transport protocol we use NAK to signal the non existence of a
common base, so fix the documentation. This helps readers of the document,
as they don't have to wonder about the difference between NAK and NACK.
As NACK is used in git archive and upload-archive, this is easy to get
wrong.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-22 13:31:55 -07:00
Michael J Gruber
cc6ee97cb3 Documentation/technical: signed merge tag format
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-17 12:10:48 -07:00
Michael J Gruber
eda2f11ee3 Documentation/technical: signed commit format
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-17 12:10:30 -07:00
Michael J Gruber
5f1abfeb69 Documentation/technical: signed tag format
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-17 11:40:58 -07:00
Michael J Gruber
76f9d8bac8 Documentation/technical: describe signature formats
We use different types of signature formats in different places.
Set up the infrastructure and overview to describe them systematically
in our technical documentation.

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-17 11:39:05 -07:00
Junio C Hamano
5d5f1c236b Merge branch 'pb/commit-verbose-config'
"git commit" learned to pay attention to "commit.verbose"
configuration variable and act as if "--verbose" option was
given from the command line.

* pb/commit-verbose-config:
  commit: add a commit.verbose config variable
  t7507-commit-verbose: improve test coverage by testing number of diffs
  parse-options.c: make OPTION_COUNTUP respect "unspecified" values
  t/t7507: improve test coverage
  t0040-parse-options: improve test coverage
  test-parse-options: print quiet as integer
  t0040-test-parse-options.sh: fix style issues
2016-05-23 14:54:32 -07:00
Junio C Hamano
5f232ecfdf Merge branch 'jc/linkgit-fix'
Many 'linkgit:<git documentation page>' references were broken,
which are all fixed with this.

* jc/linkgit-fix:
  Documentation: fix linkgit references
2016-05-17 14:38:31 -07:00
Junio C Hamano
3241d4f6fb Merge branch 'lp/typofixes'
* lp/typofixes:
  typofix: assorted typofixes in comments, documentation and messages
2016-05-17 14:38:20 -07:00
Junio C Hamano
1cca17dfff Documentation: fix linkgit references
There are a handful of incorrect "linkgit:<page>[<section>]"
instances in our documentation set.

 * Some have an extra colon after "linkgit:"; fix them by removing
   the extra colon;

 * Some refer to a page outside the Git suite, namely curl(1); fix
   them by using the `curl(1)` that already appears on the same page
   for the same purpose of referring the readers to its manual page.

 * Some spell the name of the page incorrectly, e.g. "rev-list" when
   they mean "git-rev-list"; fix them.

 * Some list the manual section incorrectly; fix them to make sure
   they match what is at the top of the target of the link.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-05-09 15:44:14 -07:00
Li Peng
832c0e5e63 typofix: assorted typofixes in comments, documentation and messages
Many instances of duplicate words (e.g. "the the path") and
a few typoes are fixed, originally in multiple patches.

    wildmatch: fix duplicate words of "the"
    t: fix duplicate words of "output"
    transport-helper: fix duplicate words of "read"
    Git.pm: fix duplicate words of "return"
    path: fix duplicate words of "look"
    pack-protocol.txt: fix duplicate words of "the"
    precompose-utf8: fix typo of "sequences"
    split-index: fix typo
    worktree.c: fix typo
    remote-ext: fix typo
    utf8: fix duplicate words of "the"
    git-cvsserver: fix duplicate words

Signed-off-by: Li Peng <lip@dtdream.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-05-06 13:16:37 -07:00
Pranit Bauva
e0070e8bd5 parse-options.c: make OPTION_COUNTUP respect "unspecified" values
OPT_COUNTUP() merely increments the counter upon --option, and resets it
to 0 upon --no-option, which means that there is no "unspecified" value
with which a client can initialize the counter to determine whether or
not --[no]-option was seen at all.

Make OPT_COUNTUP() treat any negative number as an "unspecified" value
to address this shortcoming. In particular, if a client initializes the
counter to -1, then if it is still -1 after parse_options(), then
neither --option nor --no-option was seen; if it is 0, then --no-option
was seen last, and if it is 1 or greater, than --option was seen last.

This change does not affect the behavior of existing clients because
they all use the initial value of 0 (or more).

Note that builtin/clean.c initializes the variable used with
OPT__FORCE (which uses OPT_COUNTUP()) to a negative value, but it is set
to either 0 or 1 by reading the configuration before the code calls
parse_options(), i.e. as far as parse_options() is concerned, the
initial value of the variable is not negative.

To test this behavior, in test-parse-options.c, "verbose" is set to
"unspecified" while quiet is set to 0 which will test the new behavior
with all sets of values.

Helped-by: Jeff King <peff@peff.net>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-05-05 11:52:45 -07:00
Junio C Hamano
8591654998 Merge branch 'jk/check-repository-format' into maint
The repository set-up sequence has been streamlined (the biggest
change is that there is no longer git_config_early()), so that we
do not attempt to look into refs/* when we know we do not have a
Git repository.

* jk/check-repository-format:
  verify_repository_format: mark messages for translation
  setup: drop repository_format_version global
  setup: unify repository version callbacks
  init: use setup.c's repo version verification
  setup: refactor repo format reading and verification
  config: drop git_config_early
  check_repository_format_gently: stop using git_config_early
  lazily load core.sharedrepository
  wrap shared_repository global in get/set accessors
  setup: document check_repository_format()
2016-05-02 14:24:04 -07:00
Junio C Hamano
4dda133385 Merge branch 'ep/trace-doc-sample-fix' into maint
Fix a typo in an example in the trace API documentation.

* ep/trace-doc-sample-fix:
  api-trace.txt: fix typo
2016-04-29 14:16:00 -07:00
Junio C Hamano
48adfa18bc Merge branch 'pb/opt-cmdmode-doc' into maint
Minor API documentation update.

* pb/opt-cmdmode-doc:
  api-parse-options.txt: document OPT_CMDMODE()
2016-04-14 18:37:13 -07:00
Junio C Hamano
b330051982 Merge branch 'ep/trace-doc-sample-fix'
Fix a typo in an example in the trace API documentation.

* ep/trace-doc-sample-fix:
  api-trace.txt: fix typo
2016-04-13 14:12:39 -07:00
Junio C Hamano
907c416534 Merge branch 'jk/check-repository-format'
The repository set-up sequence has been streamlined (the biggest
change is that there is no longer git_config_early()), so that we
do not attempt to look into refs/* when we know we do not have a
Git repository.

* jk/check-repository-format:
  verify_repository_format: mark messages for translation
  setup: drop repository_format_version global
  setup: unify repository version callbacks
  init: use setup.c's repo version verification
  setup: refactor repo format reading and verification
  config: drop git_config_early
  check_repository_format_gently: stop using git_config_early
  lazily load core.sharedrepository
  wrap shared_repository global in get/set accessors
  setup: document check_repository_format()
2016-04-13 14:12:28 -07:00
Junio C Hamano
8fdfaf0b2f Merge branch 'pb/opt-cmdmode-doc'
Minor API documentation update.

* pb/opt-cmdmode-doc:
  api-parse-options.txt: document OPT_CMDMODE()
2016-04-08 14:29:13 -07:00
Elia Pinto
4232b21f77 api-trace.txt: fix typo
The correct api is trace_printf_key(), not trace_print_key().

Also do not throw a random string at printf(3)-like function;
instead, feed it as a parameter that is fed to a "%s" conversion
specifier.

Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-04-05 13:51:25 -07:00
Pranit Bauva
c3f6b853bf api-parse-options.txt: document OPT_CMDMODE()
OPT_CMDMODE mechanism was introduced in the release of 1.8.5 to actively
notice when multiple "operation mode" options that specify mutually
incompatible operation modes are given.

Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-03-25 13:17:43 -07:00
Jeff King
801818680a config: drop git_config_early
There are no more callers, and it's a rather confusing
interface. This could just be folded into
git_config_with_options(), but for the sake of readability,
we'll leave it as a separate (static) helper function.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-03-11 15:02:23 -08:00
Christian Couder
3bd1b51d3a Documentation: talk about pager in api-trace.txt
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-03-07 12:23:45 -08:00
Junio C Hamano
11529ecec9 Merge branch 'jk/tighten-alloc'
Update various codepaths to avoid manually-counted malloc().

* jk/tighten-alloc: (22 commits)
  ewah: convert to REALLOC_ARRAY, etc
  convert ewah/bitmap code to use xmalloc
  diff_populate_gitlink: use a strbuf
  transport_anonymize_url: use xstrfmt
  git-compat-util: drop mempcpy compat code
  sequencer: simplify memory allocation of get_message
  test-path-utils: fix normalize_path_copy output buffer size
  fetch-pack: simplify add_sought_entry
  fast-import: simplify allocation in start_packfile
  write_untracked_extension: use FLEX_ALLOC helper
  prepare_{git,shell}_cmd: use argv_array
  use st_add and st_mult for allocation size computation
  convert trivial cases to FLEX_ARRAY macros
  use xmallocz to avoid size arithmetic
  convert trivial cases to ALLOC_ARRAY
  convert manual allocations to argv_array
  argv-array: add detach function
  add helpers for allocating flex-array structs
  harden REALLOC_ARRAY and xcalloc against size_t overflow
  tree-diff: catch integer overflow in combine_diff_path allocation
  ...
2016-02-26 13:37:16 -08:00
Jeff King
b992657ed0 argv-array: add detach function
The usual pattern for an argv array is to initialize it,
push in some strings, and then clear it when done. Very
occasionally, though, we must do other exotic things with
the memory, like freeing the list but keeping the strings.
Let's provide a detach function so that callers can make use
of our API to build up the array, and then take ownership of
it.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-02-22 14:50:32 -08:00
Knut Franke
ef976395e2 http: allow selection of proxy authentication method
CURLAUTH_ANY does not work with proxies which answer unauthenticated requests
with a 307 redirect to an error page instead of a 407 listing supported
authentication methods. Therefore, allow the authentication method to be set
using the environment variable GIT_HTTP_PROXY_AUTHMETHOD or configuration
variables http.proxyAuthmethod and remote.<name>.proxyAuthmethod (in analogy
to http.proxy and remote.<name>.proxy).

The following values are supported:

* anyauth (default)
* basic
* digest
* negotiate
* ntlm

Signed-off-by: Knut Franke <k.franke@science-computing.de>
Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Helped-by: Elia Pinto <gitter.spiros@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-01-26 10:53:09 -08:00
Junio C Hamano
b8f5242592 Merge branch 'rs/daemon-plug-child-leak' into maint
"git daemon" uses "run_command()" without "finish_command()", so it
needs to release resources itself, which it forgot to do.

* rs/daemon-plug-child-leak:
  daemon: plug memory leak
  run-command: factor out child_process_clear()
2015-11-05 12:18:17 -08:00
Junio C Hamano
bc1e0481bf Merge branch 'jc/em-dash-in-doc' into maint
AsciiDoc markup fixes.

* jc/em-dash-in-doc:
  Documentation: AsciiDoc spells em-dash as double-dashes, not triple
2015-11-04 14:20:45 -08:00
Junio C Hamano
f89baca1b9 Merge branch 'jk/repository-extension' into maint
Prepare for Git on-disk repository representation to undergo
backward incompatible changes by introducing a new repository
format version "1", with an extension mechanism.

* jk/repository-extension:
  introduce "preciousObjects" repository extension
  introduce "extensions" form of core.repositoryformatversion
2015-11-03 15:32:25 -08:00
Junio C Hamano
c3c592ef95 Merge branch 'rs/daemon-plug-child-leak'
"git daemon" uses "run_command()" without "finish_command()", so it
needs to release resources itself, which it forgot to do.

* rs/daemon-plug-child-leak:
  daemon: plug memory leak
  run-command: factor out child_process_clear()
2015-11-03 15:13:12 -08:00
René Scharfe
2d71608ec0 run-command: factor out child_process_clear()
Avoid duplication by moving the code to release allocated memory for
arguments and environment to its own function, child_process_clear().
Export it to provide a counterpart to child_process_init().

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-11-02 15:01:00 -08:00
Junio C Hamano
73167677c0 Merge branch 'jc/em-dash-in-doc'
AsciiDoc markup fixes.

* jc/em-dash-in-doc:
  Documentation: AsciiDoc spells em-dash as double-dashes, not triple
2015-10-29 13:59:16 -07:00
Junio C Hamano
fa46579555 Merge branch 'jk/repository-extension'
Prepare for Git on-disk repository representation to undergo
backward incompatible changes by introducing a new repository
format version "1", with an extension mechanism.

* jk/repository-extension:
  introduce "preciousObjects" repository extension
  introduce "extensions" form of core.repositoryformatversion
2015-10-26 15:55:25 -07:00
Junio C Hamano
3b19dba703 Documentation: AsciiDoc spells em-dash as double-dashes, not triple
Again, we do not usually process release notes with AsciiDoc, but it
is better to be consistent.

This incidentally reveals breakages left by an ancient 5e00439f
(Documentation: build html for all files in technical and howto,
2012-10-23).  The index-format documentation was originally written
to be read as straight text without formatting and when the commit
forced everything in Documentation/ to go through AsciiDoc, it did
not do any adjustment--hence the double-dashes will be seen in the
resulting text that is rendered as preformatted fixed-width without
converted into em-dashes.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-10-22 13:02:33 -07:00
Jeff King
1c9b659d98 pack-protocol: clarify LF-handling in PKT-LINE()
The spec is very inconsistent about which PKT-LINE() parts
of the grammar include a LF. On top of that, the code is not
consistent, either (e.g., send-pack does not put newlines
into the ref-update commands it sends).

Let's make explicit the long-standing expectation that we
generally expect pkt-lines to end in a newline, but that
receivers should be lenient. This makes the spec consistent,
and matches what git already does (though it does not always
fulfill the SHOULD).

We do make an exception for the push-cert, where the
receiving code is currently a bit pickier. This is a
reasonable way to be, as the data needs to be byte-for-byte
compatible with what was signed. We _could_ make up some
rules about signing a canonicalized version including
newlines, but that would require a code change, and is out
of scope for this patch.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-09-03 15:18:12 -07:00
Junio C Hamano
5a4f07b322 Merge branch 'hv/submodule-config'
The gitmodules API accessed from the C code learned to cache stuff
lazily.

* hv/submodule-config:
  submodule: allow erroneous values for the fetchRecurseSubmodules option
  submodule: use new config API for worktree configurations
  submodule: extract functions for config set and lookup
  submodule: implement a config API for lookup of .gitmodules values
2015-08-31 15:38:52 -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
Heiko Voigt
851e18c385 submodule: use new config API for worktree configurations
We remove the extracted functions and directly parse into and read out
of the cache. This allows us to have one unified way of accessing
submodule configuration values specific to single submodules. Regardless
whether we need to access a configuration from history or from the
worktree.

Signed-off-by: Heiko Voigt <hvoigt@hvoigt.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-19 11:43:10 -07:00
Heiko Voigt
959b5455d0 submodule: implement a config API for lookup of .gitmodules values
In a superproject some commands need to interact with submodules. They
need to query values from the .gitmodules file either from the worktree
of from certain revisions. At the moment this is quite hard since a
caller would need to read the .gitmodules file from the history and then
parse the values. We want to provide an API for this so we have one
place to get values from .gitmodules from any revision (including the
worktree).

The API is realized as a cache which allows us to lazily read
.gitmodules configurations by commit into a runtime cache which can then
be used to easily lookup values from it. Currently only the values for
path or name are stored but it can be extended for any value needed.

It is expected that .gitmodules files do not change often between
commits. Thats why we lookup the .gitmodules sha1 from a commit and then
either lookup an already parsed configuration or parse and cache an
unknown one for each sha1. The cache is lazily build on demand for each
requested commit.

This cache can be used for all purposes which need knowledge about
submodule configurations. Example use cases are:

 * Recursive submodule checkout needs to lookup a submodule name from
   its path when a submodule first appears. This needs be done before
   this configuration exists in the worktree.

 * The implementation of submodule support for 'git archive' needs to
   lookup the submodule name to generate the archive when given a
   revision that is not checked out.

 * 'git fetch' when given the --recurse-submodules=on-demand option (or
   configuration) needs to lookup submodule names by path from the
   database rather than reading from the worktree. For new submodule it
   needs to lookup the name from its path to allow cloning new
   submodules into the .git folder so they can be checked out without
   any network interaction when the user does a checkout of that
   revision.

Signed-off-by: Heiko Voigt <hvoigt@hvoigt.net>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-19 11:43:09 -07:00
Junio C Hamano
2e8ef44ee5 Merge branch 'ta/docfix-index-format-tech'
* ta/docfix-index-format-tech:
  typofix for index-format.txt
2015-08-17 15:07:52 -07:00
Michael Haggerty
2db69de81d lockfile: move documentation to lockfile.h and lockfile.c
Rearrange/rewrite it somewhat to fit its new environment.

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
Junio C Hamano
5f02274e4c Merge branch 'pt/pull-builtin'
Reimplement 'git pull' in C.

* pt/pull-builtin:
  pull: remove redirection to git-pull.sh
  pull --rebase: error on no merge candidate cases
  pull --rebase: exit early when the working directory is dirty
  pull: configure --rebase via branch.<name>.rebase or pull.rebase
  pull: teach git pull about --rebase
  pull: set reflog message
  pull: implement pulling into an unborn branch
  pull: fast-forward working tree if head is updated
  pull: check if in unresolved merge state
  pull: support pull.ff config
  pull: error on no merge candidates
  pull: pass git-fetch's options to git-fetch
  pull: pass git-merge's options to git-merge
  pull: pass verbosity, --progress flags to fetch and merge
  pull: implement fetch + merge
  pull: implement skeletal builtin pull
  argv-array: implement argv_array_pushv()
  parse-options-cb: implement parse_opt_passthru_argv()
  parse-options-cb: implement parse_opt_passthru()
2015-08-03 11:01:17 -07:00
Junio C Hamano
e12b51e4d6 Merge branch 'cb/parse-magnitude'
Move machinery to parse human-readable scaled numbers like 1k, 4M,
and 2G as an option parameter's value from pack-objects to
parse-options API, to make it available to other codepaths.

* cb/parse-magnitude:
  parse-options: move unsigned long option parsing out of pack-objects.c
  test-parse-options: update to handle negative ints
2015-08-03 11:01:13 -07:00
Thomas Ackermann
da4c5adae9 typofix for index-format.txt
Signed-off-by: Thomas Ackermann <th.acker@arcor.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-07-28 11:05:41 -07:00
Junio C Hamano
43f23b09bf Merge branch 'kb/use-nsec-doc'
Clarify in the Makefile a guideline to decide use of USE_NSEC.

* kb/use-nsec-doc:
  Makefile / racy-git.txt: clarify USE_NSEC prerequisites
2015-07-13 14:00:26 -07:00
Karsten Blees
b1ffafa978 Makefile / racy-git.txt: clarify USE_NSEC prerequisites
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-07-01 14:54:42 -07:00
Junio C Hamano
68538cf954 Merge branch 'sb/pack-protocol-mention-smart-http' into maint
Doc updates.

* sb/pack-protocol-mention-smart-http:
  Documentation/technical/pack-protocol: mention http as possible protocol
2015-06-25 11:02:14 -07:00
Jeff King
067fbd4105 introduce "preciousObjects" repository extension
If this extension is used in a repository, then no
operations should run which may drop objects from the object
storage. This can be useful if you are sharing that storage
with other repositories whose refs you cannot see.

For instance, if you do:

  $ git clone -s parent child
  $ git -C parent config extensions.preciousObjects true
  $ git -C parent config core.repositoryformatversion 1

you now have additional safety when running git in the
parent repository. Prunes and repacks will bail with an
error, and `git gc` will skip those operations (it will
continue to pack refs and do other non-object operations).
Older versions of git, when run in the repository, will
fail on every operation.

Note that we do not set the preciousObjects extension by
default when doing a "clone -s", as doing so breaks
backwards compatibility. It is a decision the user should
make explicitly.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-06-24 17:09:35 -07:00
Jeff King
00a09d57eb introduce "extensions" form of core.repositoryformatversion
Normally we try to avoid bumps of the whole-repository
core.repositoryformatversion field. However, it is
unavoidable if we want to safely change certain aspects of
git in a backwards-incompatible way (e.g., modifying the set
of ref tips that we must traverse to generate a list of
unreachable, safe-to-prune objects).

If we were to bump the repository version for every such
change, then any implementation understanding version `X`
would also have to understand `X-1`, `X-2`, and so forth,
even though the incompatibilities may be in orthogonal parts
of the system, and there is otherwise no reason we cannot
implement one without the other (or more importantly, that
the user cannot choose to use one feature without the other,
weighing the tradeoff in compatibility only for that
particular feature).

This patch documents the existing repositoryformatversion
strategy and introduces a new format, "1", which lets a
repository specify that it must run with an arbitrary set of
extensions. This can be used, for example:

 - to inform git that the objects should not be pruned based
   only on the reachability of the ref tips (e.g, because it
   has "clone --shared" children)

 - that the refs are stored in a format besides the usual
   "refs" and "packed-refs" directories

Because we bump to format "1", and because format "1"
requires that a running git knows about any extensions
mentioned, we know that older versions of the code will not
do something dangerous when confronted with these new
formats.

For example, if the user chooses to use database storage for
refs, they may set the "extensions.refbackend" config to
"db". Older versions of git will not understand format "1"
and bail. Versions of git which understand "1" but do not
know about "refbackend", or which know about "refbackend"
but not about the "db" backend, will refuse to run. This is
annoying, of course, but much better than the alternative of
claiming that there are no refs in the repository, or
writing to a location that other implementations will not
read.

Note that we are only defining the rules for format 1 here.
We do not ever write format 1 ourselves; it is a tool that
is meant to be used by users and future extensions to
provide safety with older implementations.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-06-24 17:09:08 -07:00