Update to Git 2.20.0

Documentation/config/core.txt

@@ -68,6 +68,14 @@ core.fsmonitor::
 	avoiding unnecessary processing of files that have not changed.
 	See the "fsmonitor-watchman" section of linkgit:githooks[5].
 
+core.virtualFilesystem::
+	If set, the value of this variable is used as a command which
+	will identify all files and directories that are present in
+	the working directory.  Git will only track and update files
+	listed in the virtual file system.  Using the virtual file system
+	will supersede the sparse-checkout settings which will be ignored.
+	See the "virtual file system" section of linkgit:githooks[6].
+
 core.trustctime::
 	If false, the ctime differences between the index and the
 	working tree are ignored; useful when the inode change time
@@ -600,6 +608,48 @@ core.multiPackIndex::
 	single index. See link:technical/multi-pack-index.html[the
 	multi-pack-index design document].
 
+core.gvfs::
+	Enable the features needed for GVFS.  This value can be set to true
+	to indicate all features should be turned on or the bit values listed
+	below can be used to turn on specific features.
++
+--
+	GVFS_SKIP_SHA_ON_INDEX::
+		Bit value 1
+		Disables the calculation of the sha when writing the index
+	GVFS_MISSING_OK::
+		Bit value 4
+		Normally git write-tree ensures that the objects referenced by the
+		directory exist in the object database. This option disables this check.
+	GVFS_NO_DELETE_OUTSIDE_SPARSECHECKOUT::
+		Bit value 8
+		When marking entries to remove from the index and the working
+		directory this option will take into account what the
+		skip-worktree bit was set to so that if the entry has the
+		skip-worktree bit set it will not be removed from the working
+		directory.  This will allow virtualized working directories to
+		detect the change to HEAD and use the new commit tree to show
+		the files that are in the working directory.
+	GVFS_FETCH_SKIP_REACHABILITY_AND_UPLOADPACK::
+		Bit value 16
+		While performing a fetch with a virtual file system we know
+		that there will be missing objects and we don't want to download
+		them just because of the reachability of the commits.  We also
+		don't want to download a pack file with commits, trees, and blobs
+		since these will be downloaded on demand.  This flag will skip the
+		checks on the reachability of objects during a fetch as well as
+		the upload pack so that extraneous objects don't get downloaded.
+	GVFS_BLOCK_FILTERS_AND_EOL_CONVERSIONS::
+		Bit value 64
+		With a virtual file system we only know the file size before any
+		CRLF or smudge/clean filters processing is done on the client.
+		To prevent file corruption due to truncation or expansion with
+		garbage at the end, these filters must not run when the file
+		is first accessed and brought down to the client. Git.exe can't
+		currently tell the first access vs subsequent accesses so this
+		flag just blocks them from occurring at all.
+--
+
 core.sparseCheckout::
 	Enable "sparse checkout" feature. See section "Sparse checkout" in
 	linkgit:git-read-tree[1] for more information.

Documentation/config/status.txt

@@ -12,6 +12,11 @@ status.branch::
 	Set to true to enable --branch by default in linkgit:git-status[1].
 	The option --no-branch takes precedence over this variable.
 
+status.aheadBehind::
+	EXPERIMENTAL, Set to true to enable --ahead-behind and false to
+	enable --no-ahead-behind by default in linkgit:git-status[1] for
+	non-porcelain status formats.  Defaults to true.
+
 status.displayCommentPrefix::
 	If set to true, linkgit:git-status[1] will insert a comment
 	prefix before each output line (starting with
@@ -70,3 +75,25 @@ status.submoduleSummary::
 	the --ignore-submodules=dirty command-line option or the 'git
 	submodule summary' command, which shows a similar output but does
 	not honor these settings.
+
+status.deserializePath::
+	EXPERIMENTAL, Pathname to a file containing cached status results
+	generated by `--serialize`.  This will be overridden by
+	`--deserialize=<path>` on the command line.  If the cache file is
+	invalid or stale, git will fall-back and compute status normally.
+
+status.deserializeWait::
+	EXPERIMENTAL, Specifies what `git status --deserialize` should do
+	if the serialization cache file is stale and whether it should
+	fall-back and compute status normally.  This will be overridden by
+	`--deserialize-wait=<value>` on the command line.
++
+--
+* `fail` - cause git to exit with an error when the status cache file
+is stale; this is intended for testing and debugging.
+* `block` - cause git to spin and periodically retry the cache file
+every 100 ms; this is intended to help coordinate with another git
+instance concurrently computing the cache file.
+* `no` - to immediately fall-back if cache file is stale.  This is the default.
+* `<timeout>` - time (in tenths of a second) to spin and retry.
+--

Documentation/fetch-options.txt

@@ -220,6 +220,19 @@ endif::git-pull[]
 	When multiple `--server-option=<option>` are given, they are all
 	sent to the other side in the order listed on the command line.
 
+--show-forced-updates::
+	By default, git checks if a branch is force-updated during
+	fetch. This can be disabled through fetch.showForcedUpdates, but
+	the --show-forced-updates option guarantees this check occurs.
+	See linkgit:git-config[1].
+
+--no-show-forced-updates::
+	By default, git checks if a branch is force-updated during
+	fetch. Pass --no-show-forced-updates or set fetch.showForcedUpdates
+	to false to skip this check for performance reasons. If used during
+	'git-pull' the --ff-only option will still check for forced updates
+	before attempting a fast-forward update. See linkgit:git-config[1].
+
 -4::
 --ipv4::
 	Use IPv4 addresses only, ignoring IPv6 addresses.

Documentation/git-status.txt

@@ -152,6 +152,21 @@ ignored, then the directory is not shown, but all contents are shown.
 	update it afterwards if any changes were detected. Defaults to
 	`--lock-index`.
 
+--serialize[=<path>]::
+	(EXPERIMENTAL) Serialize raw status results to a file or stdout
+	in a format suitable for use by `--deserialize`.  If a path is
+	given, serialize data will be written to that path *and* normal
+	status output will be written to stdout.  If path is omitted,
+	only binary serialization data will be written to stdout.
+
+--deserialize[=<path>]::
+	(EXPERIMENTAL) Deserialize raw status results from a file or
+	stdin rather than scanning the worktree.  If `<path>` is omitted
+	and `status.deserializePath` is unset, input is read from stdin.
+--no-deserialize::
+	(EXPERIMENTAL) Disable implicit deserialization of status results
+	from the value of `status.deserializePath`.
+
 <pathspec>...::
 	See the 'pathspec' entry in linkgit:gitglossary[7].
 
@@ -389,6 +404,26 @@ quoted as explained for the configuration variable `core.quotePath`
 (see linkgit:git-config[1]).
 
 
+SERIALIZATION and DESERIALIZATION (EXPERIMENTAL)
+------------------------------------------------
+
+The `--serialize` option allows git to cache the result of a
+possibly time-consuming status scan to a binary file.  A local
+service/daemon watching file system events could use this to
+periodically pre-compute a fresh status result.
+
+Interactive users could then use `--deserialize` to simply
+(and immediately) print the last-known-good result without
+waiting for the status scan.
+
+The binary serialization file format includes some worktree state
+information allowing `--deserialize` to reject the cached data
+and force a normal status scan if, for example, the commit, branch,
+or status modes/options change.  The format cannot, however, indicate
+when the cached data is otherwise stale -- that coordination belongs
+to the task driving the serializations.
+
+
 CONFIGURATION
 -------------
 

Documentation/githooks.txt

@@ -492,6 +492,44 @@ This hook is invoked by `git-p4 submit`. It takes no parameters and nothing
 from standard input. Exiting with non-zero status from this script prevent
 `git-p4 submit` from launching. Run `git-p4 submit --help` for details.
 
+virtualFilesystem
+~~~~~~~~~~~~~~~~~~
+
+"Virtual File System" allows populating the working directory sparsely.
+The projection data is typically automatically generated by an external
+process.  Git will limit what files it checks for changes as well as which
+directories are checked for untracked files based on the path names given.
+Git will also only update those files listed in the projection.
+
+The hook is invoked when the configuration option core.virtualFilesystem
+is set.  It takes one argument, a version (currently 1).
+
+The hook should output to stdout the list of all files in the working
+directory that git should track.  The paths are relative to the root
+of the working directory and are separated by a single NUL.  Full paths
+('dir1/a.txt') as well as directories are supported (ie 'dir1/').
+
+The exit status determines whether git will use the data from the
+hook.  On error, git will abort the command with an error message.
+
+post-indexchanged
+~~~~~~~~~~~~~~~~~
+
+This hook is invoked when the index is written in read-cache.c
+do_write_locked_index.
+
+The first parameter passed to the hook is the indicator for the
+working directory being updated.  "1" meaning working directory
+was updated or "0" when the working directory was not updated.
+
+The second parameter passed to the hook is the indicator for whether
+or not the index was updated and the skip-worktree bit could have
+changed.  "1" meaning skip-worktree bits could have been updated
+and "0" meaning they were not.
+
+Only one parameter should be set to "1" when the hook runs.  The hook
+running passing "1", "1" should not be possible.
+
 GIT
 ---
 Part of the linkgit:git[1] suite

Documentation/technical/read-object-protocol.txt

@@ -0,0 +1,102 @@
+Read Object Process
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The read-object process enables Git to read all missing blobs with a
+single process invocation for the entire life of a single Git command.
+This is achieved by using a packet format (pkt-line, see technical/
+protocol-common.txt) based protocol over standard input and standard
+output as follows. All packets, except for the "*CONTENT" packets and
+the "0000" flush packet, are considered text and therefore are
+terminated by a LF.
+
+Git starts the process when it encounters the first missing object that
+needs to be retrieved. After the process is started, Git sends a welcome
+message ("git-read-object-client"), a list of supported protocol version
+numbers, and a flush packet. Git expects to read a welcome response
+message ("git-read-object-server"), exactly one protocol version number
+from the previously sent list, and a flush packet. All further
+communication will be based on the selected version.
+
+The remaining protocol description below documents "version=1". Please
+note that "version=42" in the example below does not exist and is only
+there to illustrate how the protocol would look with more than one
+version.
+
+After the version negotiation Git sends a list of all capabilities that
+it supports and a flush packet. Git expects to read a list of desired
+capabilities, which must be a subset of the supported capabilities list,
+and a flush packet as response:
+------------------------
+packet: git> git-read-object-client
+packet: git> version=1
+packet: git> version=42
+packet: git> 0000
+packet: git< git-read-object-server
+packet: git< version=1
+packet: git< 0000
+packet: git> capability=get
+packet: git> capability=have
+packet: git> capability=put
+packet: git> capability=not-yet-invented
+packet: git> 0000
+packet: git< capability=get
+packet: git< 0000
+------------------------
+The only supported capability in version 1 is "get".
+
+Afterwards Git sends a list of "key=value" pairs terminated with a flush
+packet. The list will contain at least the command (based on the
+supported capabilities) and the sha1 of the object to retrieve. Please
+note, that the process must not send any response before it received the
+final flush packet.
+
+When the process receives the "get" command, it should make the requested
+object available in the git object store and then return success. Git will
+then check the object store again and this time find it and proceed.
+------------------------
+packet: git> command=get
+packet: git> sha1=0a214a649e1b3d5011e14a3dc227753f2bd2be05
+packet: git> 0000
+------------------------
+
+The process is expected to respond with a list of "key=value" pairs
+terminated with a flush packet. If the process does not experience
+problems then the list must contain a "success" status.
+------------------------
+packet: git< status=success
+packet: git< 0000
+------------------------
+
+In case the process cannot or does not want to process the content, it
+is expected to respond with an "error" status.
+------------------------
+packet: git< status=error
+packet: git< 0000
+------------------------
+
+In case the process cannot or does not want to process the content as
+well as any future content for the lifetime of the Git process, then it
+is expected to respond with an "abort" status at any point in the
+protocol.
+------------------------
+packet: git< status=abort
+packet: git< 0000
+------------------------
+
+Git neither stops nor restarts the process in case the "error"/"abort"
+status is set.
+
+If the process dies during the communication or does not adhere to the
+protocol then Git will stop the process and restart it with the next
+object that needs to be processed.
+
+After the read-object process has processed an object it is expected to
+wait for the next "key=value" list containing a command. Git will close
+the command pipe on exit. The process is expected to detect EOF and exit
+gracefully on its own. Git will wait until the process has stopped.
+
+A long running read-object process demo implementation can be found in
+`contrib/long-running-read-object/example.pl` located in the Git core
+repository. If you develop your own long running process then the
+`GIT_TRACE_PACKET` environment variables can be very helpful for
+debugging (see linkgit:git[1]).