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