Merge branch 'ns/stash'

* ns/stash:
  Documentation: quote {non-attributes} for asciidoc
  git-stash: don't complain when listing in a repo with no stash
  git-stash: fix "can't shift that many" with no arguments
  git-stash: fix "no arguments" case in documentation
  git-stash: require "save" to be explicit and update documentation
  Document git-stash
  Add git-stash script

5 files changed, 330 insertions, 1 deletions

diff --git a/.gitignore b/.gitignore
index a2a617dc62..20ee642420 100644
--- a/.gitignore
+++ b/.gitignore
@@ -124,6 +124,7 @@ git-ssh-fetch
 git-ssh-pull
 git-ssh-push
 git-ssh-upload
+git-stash
 git-status
 git-stripspace
 git-submodule
diff --git a/Documentation/cmd-list.perl b/Documentation/cmd-list.perl
index fcea1d74d5..f50f613879 100755
--- a/Documentation/cmd-list.perl
+++ b/Documentation/cmd-list.perl
@@ -178,6 +178,7 @@ git-show-ref                            plumbinginterrogators
 git-sh-setup                            purehelpers
 git-ssh-fetch                           synchingrepositories
 git-ssh-upload                          synchingrepositories
+git-stash                               mainporcelain
 git-status                              mainporcelain
 git-stripspace                          purehelpers
 git-submodule                           mainporcelain
diff --git a/Documentation/git-stash.txt b/Documentation/git-stash.txt
new file mode 100644
index 0000000000..b7d263d650
--- /dev/null
+++ b/Documentation/git-stash.txt
@@ -0,0 +1,161 @@
+git-stash(1)
+============
+
+NAME
+----
+git-stash - Stash the changes in a dirty working directory away
+
+SYNOPSIS
+--------
+[verse]
+'git-stash' (save | list | show [<stash>] | apply [<stash>] | clear)
+
+DESCRIPTION
+-----------
+
+Use 'git-stash save' when you want to record the current state of the
+working directory and the index, but want to go back to a clean
+working directory.  The command saves your local modifications away
+and reverts the working directory to match the `HEAD` commit.
+
+The modifications stashed away by this command can be listed with
+`git-stash list`, inspected with `git-stash show`, and restored
+(potentially on top of a different commit) with `git-stash apply`.
+Calling git-stash without any arguments is equivalent to `git-stash
+list`.
+
+The latest stash you created is stored in `$GIT_DIR/refs/stash`; older
+stashes are found in the reflog of this reference and can be named using
+the usual reflog syntax (e.g. `stash@\{1}` is the most recently
+created stash, `stash@\{2}` is the one before it, `stash@\{2.hours.ago}`
+is also possible).
+
+OPTIONS
+-------
+
+save::
+
+	Save your local modifications to a new 'stash', and run `git-reset
+	--hard` to revert them.
+
+list::
+
+	List the stashes that you currently have.  Each 'stash' is listed
+	with its name (e.g. `stash@\{0}` is the latest stash, `stash@\{1} is
+	the one before, etc.), the name of the branch that was current when the
+	stash was made, and a short description of the commit the stash was
+	based on.
++
+----------------------------------------------------------------
+stash@{0}: submit: 6ebd0e2... Add git-stash
+stash@{1}: master: 9cc0589... Merge branch 'master' of gfi
+----------------------------------------------------------------
+
+show [<stash>]::
+
+	Show the changes recorded in the stash as a diff between the the
+	stashed state and its original parent. When no `<stash>` is given,
+	shows the latest one. By default, the command shows the diffstat, but
+	it will accept any format known to `git-diff` (e.g., `git-stash show
+	-p stash@\{2}` to view the second most recent stash in patch form).
+
+apply [<stash>]::
+
+	Restore the changes recorded in the stash on top of the current
+	working tree state.  When no `<stash>` is given, applies the latest
+	one.  The working directory must match the index.
++
+This operation can fail with conflicts; you need to resolve them
+by hand in the working tree.
+
+clear::
+	Remove all the stashed states. Note that those states will then
+	be subject to pruning, and may be difficult or impossible to recover.
+
+
+DISCUSSION
+----------
+
+A stash is represented as a commit whose tree records the state of the
+working directory, and its first parent is the commit at `HEAD` when
+the stash was created.  The tree of the second parent records the
+state of the index when the stash is made, and it is made a child of
+the `HEAD` commit.  The ancestry graph looks like this:
+
+            .----W
+           /    /
+     ...--H----I
+
+where `H` is the `HEAD` commit, `I` is a commit that records the state
+of the index, and `W` is a commit that records the state of the working
+tree.
+
+
+EXAMPLES
+--------
+
+Pulling into a dirty tree::
+
+When you are in the middle of something, you learn that there are
+upstream changes that are possibly relevant to what you are
+doing.  When your local changes do not conflict with the changes in
+the upstream, a simple `git pull` will let you move forward.
++
+However, there are cases in which your local changes do conflict with
+the upstream changes, and `git pull` refuses to overwrite your
+changes.  In such a case, you can stash your changes away,
+perform a pull, and then unstash, like this:
++
+----------------------------------------------------------------
+$ git pull
+...
+file foobar not up to date, cannot merge.
+$ git stash
+$ git pull
+$ git stash apply
+----------------------------------------------------------------
+
+Interrupted workflow::
+
+When you are in the middle of something, your boss comes in and
+demands that you fix something immediately.  Traditionally, you would
+make a commit to a temporary branch to store your changes away, and
+return to your original branch to make the emergency fix, like this:
++
+----------------------------------------------------------------
+... hack hack hack ...
+$ git checkout -b my_wip
+$ git commit -a -m "WIP"
+$ git checkout master
+$ edit emergency fix
+$ git commit -a -m "Fix in a hurry"
+$ git checkout my_wip
+$ git reset --soft HEAD^
+... continue hacking ...
+----------------------------------------------------------------
++
+You can use `git-stash` to simplify the above, like this:
++
+----------------------------------------------------------------
+... hack hack hack ...
+$ git stash
+$ edit emergency fix
+$ git commit -a -m "Fix in a hurry"
+$ git stash apply
+... continue hacking ...
+----------------------------------------------------------------
+
+SEE ALSO
+--------
+gitlink:git-checkout[1],
+gitlink:git-commit[1],
+gitlink:git-reflog[1],
+gitlink:git-reset[1]
+
+AUTHOR
+------
+Written by Nanako Shiraishi <nanako3@bluebottle.com>
+
+GIT
+---
+Part of the gitlink:git[7] suite
diff --git a/Makefile b/Makefile
index eed6bd5770..90597edfc7 100644
--- a/Makefile
+++ b/Makefile
@@ -212,7 +212,8 @@ SCRIPT_SH = \
 	git-merge.sh git-merge-stupid.sh git-merge-octopus.sh \
 	git-merge-resolve.sh git-merge-ours.sh \
 	git-lost-found.sh git-quiltimport.sh git-submodule.sh \
-	git-filter-branch.sh
+	git-filter-branch.sh \
+	git-stash.sh
 
 SCRIPT_PERL = \
 	git-add--interactive.perl \
diff --git a/git-stash.sh b/git-stash.sh
new file mode 100755
index 0000000000..18d3322ab5
--- /dev/null
+++ b/git-stash.sh
@@ -0,0 +1,165 @@
+#!/bin/sh
+# Copyright (c) 2007, Nanako Shiraishi
+
+USAGE='[ | list | show | apply | clear]'
+
+. git-sh-setup
+require_work_tree
+
+TMP="$GIT_DIR/.git-stash.$$"
+trap 'rm -f "$TMP-*"' 0
+
+ref_stash=refs/stash
+
+no_changes () {
+	git-diff-index --quiet --cached HEAD &&
+	git-diff-files --quiet
+}
+
+clear_stash () {
+	logfile="$GIT_DIR/logs/$ref_stash" &&
+	mkdir -p "$(dirname "$logfile")" &&
+	: >"$logfile"
+}
+
+save_stash () {
+	if no_changes
+	then
+		echo >&2 'No local changes to save'
+		exit 0
+	fi
+	test -f "$GIT_DIR/logs/$ref_stash" ||
+		clear_stash || die "Cannot initialize stash"
+
+	# state of the base commit
+	if b_commit=$(git-rev-parse --verify HEAD)
+	then
+		head=$(git-log --abbrev-commit --pretty=oneline -n 1 HEAD)
+	else
+		die "You do not have the initial commit yet"
+	fi
+
+	if branch=$(git-symbolic-ref -q HEAD)
+	then
+		branch=${branch#refs/heads/}
+	else
+		branch='(no branch)'
+	fi
+	msg=$(printf '%s: %s' "$branch" "$head")
+
+	# state of the index
+	i_tree=$(git-write-tree) &&
+	i_commit=$(printf 'index on %s' "$msg" |
+		git-commit-tree $i_tree -p $b_commit) ||
+		die "Cannot save the current index state"
+
+	# state of the working tree
+	w_tree=$( (
+		GIT_INDEX_FILE="$TMP-index" &&
+		export GIT_INDEX_FILE &&
+
+		rm -f "$TMP-index" &&
+		git-read-tree $i_tree &&
+		git-add -u &&
+		git-write-tree &&
+		rm -f "$TMP-index"
+	) ) ||
+		die "Cannot save the current worktree state"
+
+	# create the stash
+	w_commit=$(printf 'WIP on %s' "$msg" |
+		git-commit-tree $w_tree -p $b_commit -p $i_commit) ||
+		die "Cannot record working tree state"
+
+	git-update-ref -m "$msg" $ref_stash $w_commit ||
+		die "Cannot save the current status"
+	printf >&2 'Saved WIP on %s\n' "$msg"
+}
+
+have_stash () {
+	git-rev-parse --verify $ref_stash >/dev/null 2>&1
+}
+
+list_stash () {
+	have_stash || return 0
+	git-log --pretty=oneline -g "$@" $ref_stash |
+	sed -n -e 's/^[.0-9a-f]* refs\///p'
+}
+
+show_stash () {
+	flags=$(git-rev-parse --no-revs --flags "$@")
+	if test -z "$flags"
+	then
+		flags=--stat
+	fi
+	s=$(git-rev-parse --revs-only --no-flags --default $ref_stash "$@")
+
+	w_commit=$(git-rev-parse --verify "$s") &&
+	b_commit=$(git-rev-parse --verify "$s^") &&
+	git-diff $flags $b_commit $w_commit
+}
+
+apply_stash () {
+	git-diff-files --quiet ||
+		die 'Cannot restore on top of a dirty state'
+
+	# current index state
+	c_tree=$(git-write-tree) ||
+		die 'Cannot apply a stash in the middle of a merge'
+
+	s=$(git-rev-parse --revs-only --no-flags --default $ref_stash "$@") &&
+	w_tree=$(git-rev-parse --verify "$s:") &&
+	b_tree=$(git-rev-parse --verify "$s^:") ||
+		die "$*: no valid stashed state found"
+
+	eval "
+		GITHEAD_$w_tree='Stashed changes' &&
+		GITHEAD_$c_tree='Updated upstream' &&
+		GITHEAD_$b_tree='Version stash was based on' &&
+		export GITHEAD_$w_tree GITHEAD_$c_tree GITHEAD_$b_tree
+	"
+
+	if git-merge-recursive $b_tree -- $c_tree $w_tree
+	then
+		# No conflict
+		a="$TMP-added" &&
+		git-diff --cached --name-only --diff-filter=A $c_tree >"$a" &&
+		git-read-tree --reset $c_tree &&
+		git-update-index --add --stdin <"$a" ||
+			die "Cannot unstage modified files"
+		git-status
+		rm -f "$a"
+	else
+		# Merge conflict; keep the exit status from merge-recursive
+		exit
+	fi
+}
+
+# Main command set
+case "$1" in
+list | '')
+	test $# -gt 0 && shift
+	if test $# = 0
+	then
+		set x -n 10
+		shift
+	fi
+	list_stash "$@"
+	;;
+show)
+	shift
+	show_stash "$@"
+	;;
+apply)
+	shift
+	apply_stash "$@"
+	;;
+clear)
+	clear_stash
+	;;
+save)
+	save_stash && git-reset --hard
+	;;
+*)
+	usage
+esac