git/git-pull.sh
Jeff King 9f48f2bd9a pull: update unborn branch tip after index
When commit d09e79c taught git to pull into an unborn
branch, it first updated the unborn branch to point at the
pulled commit, and then used read-tree to update the index
and working tree. That ordering made sense, since any
failure of the latter step would be due to filesystem
errors, and one could then recover with "git reset --hard".

Later, commit 4b3ffe5 added extra safety for existing files
in the working tree by asking read-tree to bail out when it
would overwrite such a file. This error mode is much less
"your pull failed due to random errors" and more like "we
reject this pull because it would lose data". In that case,
it makes sense not to update the HEAD ref, just as a regular
rejected merge would do.

This patch reverses the order of the update-ref and
read-tree calls, so that we do not touch the HEAD ref at all if a
merge is rejected. This also means that we would not update
HEAD in case of a transient filesystem error, but those are
presumably less rare (and one can still recover by repeating
the pull, or by accessing FETCH_HEAD directly).

While we're reorganizing the code, we can drop the "exit 1"
from the end of our command chain. We exit immediately
either way, and just calling exit without an argument will
use the exit code from the last command.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-06-20 15:51:25 -07:00

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#!/bin/sh
#
# Copyright (c) 2005 Junio C Hamano
#
# Fetch one or more remote refs and merge it/them into the current HEAD.
USAGE='[-n | --no-stat] [--[no-]commit] [--[no-]squash] [--[no-]ff] [-s strategy]... [<fetch-options>] <repo> <head>...'
LONG_USAGE='Fetch one or more remote refs and merge it/them into the current HEAD.'
SUBDIRECTORY_OK=Yes
OPTIONS_SPEC=
. git-sh-setup
. git-sh-i18n
set_reflog_action "pull${1+ $*}"
require_work_tree_exists
cd_to_toplevel
die_conflict () {
git diff-index --cached --name-status -r --ignore-submodules HEAD --
if [ $(git config --bool --get advice.resolveConflict || echo true) = "true" ]; then
die "$(gettext "Pull is not possible because you have unmerged files.
Please, fix them up in the work tree, and then use 'git add/rm <file>'
as appropriate to mark resolution, or use 'git commit -a'.")"
else
die "$(gettext "Pull is not possible because you have unmerged files.")"
fi
}
die_merge () {
if [ $(git config --bool --get advice.resolveConflict || echo true) = "true" ]; then
die "$(gettext "You have not concluded your merge (MERGE_HEAD exists).
Please, commit your changes before you can merge.")"
else
die "$(gettext "You have not concluded your merge (MERGE_HEAD exists).")"
fi
}
test -z "$(git ls-files -u)" || die_conflict
test -f "$GIT_DIR/MERGE_HEAD" && die_merge
strategy_args= diffstat= no_commit= squash= no_ff= ff_only=
log_arg= verbosity= progress= recurse_submodules=
merge_args= edit=
curr_branch=$(git symbolic-ref -q HEAD)
curr_branch_short="${curr_branch#refs/heads/}"
rebase=$(git config --bool branch.$curr_branch_short.rebase)
if test -z "$rebase"
then
rebase=$(git config --bool pull.rebase)
fi
dry_run=
while :
do
case "$1" in
-q|--quiet)
verbosity="$verbosity -q" ;;
-v|--verbose)
verbosity="$verbosity -v" ;;
--progress)
progress=--progress ;;
--no-progress)
progress=--no-progress ;;
-n|--no-stat|--no-summary)
diffstat=--no-stat ;;
--stat|--summary)
diffstat=--stat ;;
--log|--no-log)
log_arg=$1 ;;
--no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
no_commit=--no-commit ;;
--c|--co|--com|--comm|--commi|--commit)
no_commit=--commit ;;
-e|--edit)
edit=--edit ;;
--no-edit)
edit=--no-edit ;;
--sq|--squ|--squa|--squas|--squash)
squash=--squash ;;
--no-sq|--no-squ|--no-squa|--no-squas|--no-squash)
squash=--no-squash ;;
--ff)
no_ff=--ff ;;
--no-ff)
no_ff=--no-ff ;;
--ff-only)
ff_only=--ff-only ;;
-s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
--strateg=*|--strategy=*|\
-s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
case "$#,$1" in
*,*=*)
strategy=`expr "z$1" : 'z-[^=]*=\(.*\)'` ;;
1,*)
usage ;;
*)
strategy="$2"
shift ;;
esac
strategy_args="${strategy_args}-s $strategy "
;;
-X*)
case "$#,$1" in
1,-X)
usage ;;
*,-X)
xx="-X $(git rev-parse --sq-quote "$2")"
shift ;;
*,*)
xx=$(git rev-parse --sq-quote "$1") ;;
esac
merge_args="$merge_args$xx "
;;
-r|--r|--re|--reb|--reba|--rebas|--rebase)
rebase=true
;;
--no-r|--no-re|--no-reb|--no-reba|--no-rebas|--no-rebase)
rebase=false
;;
--recurse-submodules)
recurse_submodules=--recurse-submodules
;;
--recurse-submodules=*)
recurse_submodules="$1"
;;
--no-recurse-submodules)
recurse_submodules=--no-recurse-submodules
;;
--d|--dr|--dry|--dry-|--dry-r|--dry-ru|--dry-run)
dry_run=--dry-run
;;
-h|--help-all)
usage
;;
*)
# Pass thru anything that may be meant for fetch.
break
;;
esac
shift
done
error_on_no_merge_candidates () {
exec >&2
for opt
do
case "$opt" in
-t|--t|--ta|--tag|--tags)
echo "Fetching tags only, you probably meant:"
echo " git fetch --tags"
exit 1
esac
done
if test true = "$rebase"
then
op_type=rebase
op_prep=against
else
op_type=merge
op_prep=with
fi
curr_branch=${curr_branch#refs/heads/}
upstream=$(git config "branch.$curr_branch.merge")
remote=$(git config "branch.$curr_branch.remote")
if [ $# -gt 1 ]; then
if [ "$rebase" = true ]; then
printf "There is no candidate for rebasing against "
else
printf "There are no candidates for merging "
fi
echo "among the refs that you just fetched."
echo "Generally this means that you provided a wildcard refspec which had no"
echo "matches on the remote end."
elif [ $# -gt 0 ] && [ "$1" != "$remote" ]; then
echo "You asked to pull from the remote '$1', but did not specify"
echo "a branch. Because this is not the default configured remote"
echo "for your current branch, you must specify a branch on the command line."
elif [ -z "$curr_branch" -o -z "$upstream" ]; then
. git-parse-remote
error_on_missing_default_upstream "pull" $op_type $op_prep \
"git pull <remote> <branch>"
else
echo "Your configuration specifies to $op_type $op_prep the ref '${upstream#refs/heads/}'"
echo "from the remote, but no such ref was fetched."
fi
exit 1
}
test true = "$rebase" && {
if ! git rev-parse -q --verify HEAD >/dev/null
then
# On an unborn branch
if test -f "$GIT_DIR/index"
then
die "$(gettext "updating an unborn branch with changes added to the index")"
fi
else
require_clean_work_tree "pull with rebase" "Please commit or stash them."
fi
oldremoteref= &&
test -n "$curr_branch" &&
. git-parse-remote &&
remoteref="$(get_remote_merge_branch "$@" 2>/dev/null)" &&
oldremoteref="$(git rev-parse -q --verify "$remoteref")" &&
for reflog in $(git rev-list -g $remoteref 2>/dev/null)
do
if test "$reflog" = "$(git merge-base $reflog $curr_branch)"
then
oldremoteref="$reflog"
break
fi
done
}
orig_head=$(git rev-parse -q --verify HEAD)
git fetch $verbosity $progress $dry_run $recurse_submodules --update-head-ok "$@" || exit 1
test -z "$dry_run" || exit 0
curr_head=$(git rev-parse -q --verify HEAD)
if test -n "$orig_head" && test "$curr_head" != "$orig_head"
then
# The fetch involved updating the current branch.
# The working tree and the index file is still based on the
# $orig_head commit, but we are merging into $curr_head.
# First update the working tree to match $curr_head.
eval_gettextln "Warning: fetch updated the current branch head.
Warning: fast-forwarding your working tree from
Warning: commit \$orig_head." >&2
git update-index -q --refresh
git read-tree -u -m "$orig_head" "$curr_head" ||
die "$(eval_gettext "Cannot fast-forward your working tree.
After making sure that you saved anything precious from
$ git diff \$orig_head
output, run
$ git reset --hard
to recover.")"
fi
merge_head=$(sed -e '/ not-for-merge /d' \
-e 's/ .*//' "$GIT_DIR"/FETCH_HEAD | \
tr '\012' ' ')
case "$merge_head" in
'')
error_on_no_merge_candidates "$@"
;;
?*' '?*)
if test -z "$orig_head"
then
die "$(gettext "Cannot merge multiple branches into empty head")"
fi
if test true = "$rebase"
then
die "$(gettext "Cannot rebase onto multiple branches")"
fi
;;
esac
if test -z "$orig_head"
then
git read-tree -m -u $merge_head &&
git update-ref -m "initial pull" HEAD $merge_head "$curr_head"
exit
fi
if test true = "$rebase"
then
o=$(git show-branch --merge-base $curr_branch $merge_head $oldremoteref)
if test "$oldremoteref" = "$o"
then
unset oldremoteref
fi
fi
merge_name=$(git fmt-merge-msg $log_arg <"$GIT_DIR/FETCH_HEAD") || exit
case "$rebase" in
true)
eval="git-rebase $diffstat $strategy_args $merge_args $verbosity"
eval="$eval --onto $merge_head ${oldremoteref:-$merge_head}"
;;
*)
eval="git-merge $diffstat $no_commit $edit $squash $no_ff $ff_only"
eval="$eval $log_arg $strategy_args $merge_args $verbosity $progress"
eval="$eval \"\$merge_name\" HEAD $merge_head"
;;
esac
eval "exec $eval"