git-checkout.sh

   1 #!/bin/sh
   2
   3 USAGE='[-f] [-b <new_branch>] [-m] [<branch>] [<paths>...]'
   4 SUBDIRECTORY_OK=Sometimes
   5 . git-sh-setup
   6
   7 old=$(git-rev-parse HEAD)
   8 old_name=HEAD
   9 new=
  10 new_name=
  11 force=
  12 branch=
  13 newbranch=
  14 newbranch_log=
  15 merge=
  16 while [ "$#" != "0" ]; do
  17     arg="$1"
  18     shift
  19     case "$arg" in
  20         "-b")
  21                 newbranch="$1"
  22                 shift
  23                 [ -z "$newbranch" ] &&
  24                         die "git checkout: -b needs a branch name"
  25                 [ -e "$GIT_DIR/refs/heads/$newbranch" ] &&
  26                         die "git checkout: branch $newbranch already exists"
  27                 git-check-ref-format "heads/$newbranch" ||
  28                         die "git checkout: we do not like '$newbranch' as a branch name."
  29                 ;;
  30         "-l")
  31                 newbranch_log=1
  32                 ;;
  33         "-f")
  34                 force=1
  35                 ;;
  36         -m)
  37                 merge=1
  38                 ;;
  39         --)
  40                 break
  41                 ;;
  42         -*)
  43                 usage
  44                 ;;
  45         *)
  46                 if rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null)
  47                 then
  48                         if [ -z "$rev" ]; then
  49                                 echo "unknown flag $arg"
  50                                 exit 1
  51                         fi
  52                         new="$rev"
  53                         new_name="$arg^0"
  54                         if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
  55                                 branch="$arg"
  56                         fi
  57                 elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
  58                 then
  59                         # checking out selected paths from a tree-ish.
  60                         new="$rev"
  61                         new_name="$arg^{tree}"
  62                         branch=
  63                 else
  64                         new=
  65                         new_name=
  66                         branch=
  67                         set x "$arg" "$@"
  68                         shift
  69                 fi
  70                 break
  71                 ;;
  72     esac
  73 done
  74
  75 # The behaviour of the command with and without explicit path
  76 # parameters is quite different.
  77 #
  78 # Without paths, we are checking out everything in the work tree,
  79 # possibly switching branches.  This is the traditional behaviour.
  80 #
  81 # With paths, we are _never_ switching branch, but checking out
  82 # the named paths from either index (when no rev is given),
  83 # or the named tree-ish (when rev is given).
  84
  85 if test "$#" -ge 1
  86 then
  87         hint=
  88         if test "$#" -eq 1
  89         then
  90                 hint="
  91 Did you intend to checkout '$@' which can not be resolved as commit?"
  92         fi
  93         if test '' != "$newbranch$force$merge"
  94         then
  95                 die "git checkout: updating paths is incompatible with switching branches/forcing$hint"
  96         fi
  97         if test '' != "$new"
  98         then
  99                 # from a specific tree-ish; note that this is for
 100                 # rescuing paths and is never meant to remove what
 101                 # is not in the named tree-ish.
 102                 git-ls-tree --full-name -r "$new" "$@" |
 103                 git-update-index --index-info || exit $?
 104         fi
 105         git-checkout-index -f -u -- "$@"
 106         exit $?
 107 else
 108         # Make sure we did not fall back on $arg^{tree} codepath
 109         # since we are not checking out from an arbitrary tree-ish,
 110         # but switching branches.
 111         if test '' != "$new"
 112         then
 113                 git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 ||
 114                 die "Cannot switch branch to a non-commit."
 115         fi
 116 fi
 117
 118 # We are switching branches and checking out trees, so
 119 # we *NEED* to be at the toplevel.
 120 cdup=$(git-rev-parse --show-cdup)
 121 if test ! -z "$cdup"
 122 then
 123         cd "$cdup"
 124 fi
 125
 126 [ -z "$new" ] && new=$old && new_name="$old_name"
 127
 128 # If we don't have an old branch that we're switching to,
 129 # and we don't have a new branch name for the target we
 130 # are switching to, then we'd better just be checking out
 131 # what we already had
 132
 133 [ -z "$branch$newbranch" ] &&
 134         [ "$new" != "$old" ] &&
 135         die "git checkout: to checkout the requested commit you need to specify
 136               a name for a new branch which is created and switched to"
 137
 138 if [ "$force" ]
 139 then
 140     git-read-tree --reset -u $new
 141 else
 142     git-update-index --refresh >/dev/null
 143     merge_error=$(git-read-tree -m -u $old $new 2>&1) || (
 144         case "$merge" in
 145         '')
 146                 echo >&2 "$merge_error"
 147                 exit 1 ;;
 148         esac
 149
 150         # Match the index to the working tree, and do a three-way.
 151         git diff-files --name-only | git update-index --remove --stdin &&
 152         work=`git write-tree` &&
 153         git read-tree --reset -u $new &&
 154         git read-tree -m -u --aggressive $old $new $work || exit
 155
 156         if result=`git write-tree 2>/dev/null`
 157         then
 158             echo >&2 "Trivially automerged."
 159         else
 160             git merge-index -o git-merge-one-file -a
 161         fi
 162
 163         # Do not register the cleanly merged paths in the index yet.
 164         # this is not a real merge before committing, but just carrying
 165         # the working tree changes along.
 166         unmerged=`git ls-files -u`
 167         git read-tree --reset $new
 168         case "$unmerged" in
 169         '')     ;;
 170         *)
 171                 (
 172                         z40=0000000000000000000000000000000000000000
 173                         echo "$unmerged" |
 174                         sed -e 's/^[0-7]* [0-9a-f]* /'"0 $z40 /"
 175                         echo "$unmerged"
 176                 ) | git update-index --index-info
 177                 ;;
 178         esac
 179         exit 0
 180     )
 181     saved_err=$?
 182     if test "$saved_err" = 0
 183     then
 184         test "$new" = "$old" || git diff-index --name-status "$new"
 185     fi
 186     (exit $saved_err)
 187 fi
 188
 189 #
 190 # Switch the HEAD pointer to the new branch if we
 191 # checked out a branch head, and remove any potential
 192 # old MERGE_HEAD's (subsequent commits will clearly not
 193 # be based on them, since we re-set the index)
 194 #
 195 if [ "$?" -eq 0 ]; then
 196         if [ "$newbranch" ]; then
 197                 if [ "$newbranch_log" ]; then
 198                         mkdir -p $(dirname "$GIT_DIR/logs/refs/heads/$newbranch")
 199                         touch "$GIT_DIR/logs/refs/heads/$newbranch"
 200                 fi
 201                 git-update-ref -m "checkout: Created from $new_name" "refs/heads/$newbranch" $new || exit
 202                 branch="$newbranch"
 203         fi
 204         [ "$branch" ] &&
 205         GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
 206         rm -f "$GIT_DIR/MERGE_HEAD"
 207 else
 208         exit 1
 209 fi