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