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_name=HEAD
   8 old=$(git-rev-parse --verify $old_name 2>/dev/null)
   9 new=
  10 new_name=
  11 force=
  12 branch=
  13 newbranch=
  14 newbranch_log=
  15 merge=
  16 while [ "$#" != "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                 git-show-ref --verify --quiet -- "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="$arg^0"
  54                         if git-show-ref --verify --quiet -- "refs/heads/$arg"
  55                         then
  56                                 branch="$arg"
  57                         fi
  58                 elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
  59                 then
  60                         # checking out selected paths from a tree-ish.
  61                         new="$rev"
  62                         new_name="$arg^{tree}"
  63                         branch=
  64                 else
  65                         new=
  66                         new_name=
  67                         branch=
  68                         set x "$arg" "$@"
  69                         shift
  70                 fi
  71                 case "$1" in
  72                 --)
  73                         shift ;;
  74                 esac
  75                 break
  76                 ;;
  77     esac
  78 done
  79
  80 case "$force$merge" in
  81 11)
  82         die "git checkout: -f and -m are incompatible"
  83 esac
  84
  85 # The behaviour of the command with and without explicit path
  86 # parameters is quite different.
  87 #
  88 # Without paths, we are checking out everything in the work tree,
  89 # possibly switching branches.  This is the traditional behaviour.
  90 #
  91 # With paths, we are _never_ switching branch, but checking out
  92 # the named paths from either index (when no rev is given),
  93 # or the named tree-ish (when rev is given).
  94
  95 if test "$#" -ge 1
  96 then
  97         hint=
  98         if test "$#" -eq 1
  99         then
 100                 hint="
 101 Did you intend to checkout '$@' which can not be resolved as commit?"
 102         fi
 103         if test '' != "$newbranch$force$merge"
 104         then
 105                 die "git checkout: updating paths is incompatible with switching branches/forcing$hint"
 106         fi
 107         if test '' != "$new"
 108         then
 109                 # from a specific tree-ish; note that this is for
 110                 # rescuing paths and is never meant to remove what
 111                 # is not in the named tree-ish.
 112                 git-ls-tree --full-name -r "$new" "$@" |
 113                 git-update-index --index-info || exit $?
 114         fi
 115         git-checkout-index -f -u -- "$@"
 116         exit $?
 117 else
 118         # Make sure we did not fall back on $arg^{tree} codepath
 119         # since we are not checking out from an arbitrary tree-ish,
 120         # but switching branches.
 121         if test '' != "$new"
 122         then
 123                 git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 ||
 124                 die "Cannot switch branch to a non-commit."
 125         fi
 126 fi
 127
 128 # We are switching branches and checking out trees, so
 129 # we *NEED* to be at the toplevel.
 130 cdup=$(git-rev-parse --show-cdup)
 131 if test ! -z "$cdup"
 132 then
 133         cd "$cdup"
 134 fi
 135
 136 [ -z "$new" ] && new=$old && new_name="$old_name"
 137
 138 # If we don't have an old branch that we're switching to,
 139 # and we don't have a new branch name for the target we
 140 # are switching to, then we'd better just be checking out
 141 # what we already had
 142
 143 [ -z "$branch$newbranch" ] &&
 144         [ "$new" != "$old" ] &&
 145         die "git checkout: to checkout the requested commit you need to specify
 146               a name for a new branch which is created and switched to"
 147
 148 if [ "X$old" = X ]
 149 then
 150         echo "warning: You do not appear to currently be on a branch." >&2
 151         echo "warning: Forcing checkout of $new_name." >&2
 152         force=1
 153 fi
 154
 155 if [ "$force" ]
 156 then
 157     git-read-tree --reset -u $new
 158 else
 159     git-update-index --refresh >/dev/null
 160     merge_error=$(git-read-tree -m -u $old $new 2>&1) || (
 161         case "$merge" in
 162         '')
 163                 echo >&2 "$merge_error"
 164                 exit 1 ;;
 165         esac
 166
 167         # Match the index to the working tree, and do a three-way.
 168         git diff-files --name-only | git update-index --remove --stdin &&
 169         work=`git write-tree` &&
 170         git read-tree --reset -u $new &&
 171         git read-tree -m -u --aggressive $old $new $work || exit
 172
 173         if result=`git write-tree 2>/dev/null`
 174         then
 175             echo >&2 "Trivially automerged."
 176         else
 177             git merge-index -o git-merge-one-file -a
 178         fi
 179
 180         # Do not register the cleanly merged paths in the index yet.
 181         # this is not a real merge before committing, but just carrying
 182         # the working tree changes along.
 183         unmerged=`git ls-files -u`
 184         git read-tree --reset $new
 185         case "$unmerged" in
 186         '')     ;;
 187         *)
 188                 (
 189                         z40=0000000000000000000000000000000000000000
 190                         echo "$unmerged" |
 191                         sed -e 's/^[0-7]* [0-9a-f]* /'"0 $z40 /"
 192                         echo "$unmerged"
 193                 ) | git update-index --index-info
 194                 ;;
 195         esac
 196         exit 0
 197     )
 198     saved_err=$?
 199     if test "$saved_err" = 0
 200     then
 201         test "$new" = "$old" || git diff-index --name-status "$new"
 202     fi
 203     (exit $saved_err)
 204 fi
 205
 206 #
 207 # Switch the HEAD pointer to the new branch if we
 208 # checked out a branch head, and remove any potential
 209 # old MERGE_HEAD's (subsequent commits will clearly not
 210 # be based on them, since we re-set the index)
 211 #
 212 if [ "$?" -eq 0 ]; then
 213         if [ "$newbranch" ]; then
 214                 if [ "$newbranch_log" ]; then
 215                         mkdir -p $(dirname "$GIT_DIR/logs/refs/heads/$newbranch")
 216                         touch "$GIT_DIR/logs/refs/heads/$newbranch"
 217                 fi
 218                 git-update-ref -m "checkout: Created from $new_name" "refs/heads/$newbranch" $new || exit
 219                 branch="$newbranch"
 220         fi
 221         [ "$branch" ] &&
 222         GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
 223         rm -f "$GIT_DIR/MERGE_HEAD"
 224 else
 225         exit 1
 226 fi