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