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 require_work_tree
   7
   8 old_name=HEAD
   9 old=$(git-rev-parse --verify $old_name 2>/dev/null)
  10 new=
  11 new_name=
  12 force=
  13 branch=
  14 newbranch=
  15 newbranch_log=
  16 merge=
  17 while [ "$#" != "0" ]; do
  18     arg="$1"
  19     shift
  20     case "$arg" in
  21         "-b")
  22                 newbranch="$1"
  23                 shift
  24                 [ -z "$newbranch" ] &&
  25                         die "git checkout: -b needs a branch name"
  26                 git-show-ref --verify --quiet -- "refs/heads/$newbranch" &&
  27                         die "git checkout: branch $newbranch already exists"
  28                 git-check-ref-format "heads/$newbranch" ||
  29                         die "git checkout: we do not like '$newbranch' as a branch name."
  30                 ;;
  31         "-l")
  32                 newbranch_log=1
  33                 ;;
  34         "-f")
  35                 force=1
  36                 ;;
  37         -m)
  38                 merge=1
  39                 ;;
  40         --)
  41                 break
  42                 ;;
  43         -*)
  44                 usage
  45                 ;;
  46         *)
  47                 if rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null)
  48                 then
  49                         if [ -z "$rev" ]; then
  50                                 echo "unknown flag $arg"
  51                                 exit 1
  52                         fi
  53                         new="$rev"
  54                         new_name="$arg^0"
  55                         if git-show-ref --verify --quiet -- "refs/heads/$arg"
  56                         then
  57                                 branch="$arg"
  58                         fi
  59                 elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
  60                 then
  61                         # checking out selected paths from a tree-ish.
  62                         new="$rev"
  63                         new_name="$arg^{tree}"
  64                         branch=
  65                 else
  66                         new=
  67                         new_name=
  68                         branch=
  69                         set x "$arg" "$@"
  70                         shift
  71                 fi
  72                 case "$1" in
  73                 --)
  74                         shift ;;
  75                 esac
  76                 break
  77                 ;;
  78     esac
  79 done
  80
  81 case "$force$merge" in
  82 11)
  83         die "git checkout: -f and -m are incompatible"
  84 esac
  85
  86 # The behaviour of the command with and without explicit path
  87 # parameters is quite different.
  88 #
  89 # Without paths, we are checking out everything in the work tree,
  90 # possibly switching branches.  This is the traditional behaviour.
  91 #
  92 # With paths, we are _never_ switching branch, but checking out
  93 # the named paths from either index (when no rev is given),
  94 # or the named tree-ish (when rev is given).
  95
  96 if test "$#" -ge 1
  97 then
  98         hint=
  99         if test "$#" -eq 1
 100         then
 101                 hint="
 102 Did you intend to checkout '$@' which can not be resolved as commit?"
 103         fi
 104         if test '' != "$newbranch$force$merge"
 105         then
 106                 die "git checkout: updating paths is incompatible with switching branches/forcing$hint"
 107         fi
 108         if test '' != "$new"
 109         then
 110                 # from a specific tree-ish; note that this is for
 111                 # rescuing paths and is never meant to remove what
 112                 # is not in the named tree-ish.
 113                 git-ls-tree --full-name -r "$new" "$@" |
 114                 git-update-index --index-info || exit $?
 115         fi
 116
 117         # Make sure the request is about existing paths.
 118         git-ls-files --error-unmatch -- "$@" >/dev/null || exit
 119         git-ls-files -- "$@" |
 120         git-checkout-index -f -u --stdin
 121         exit $?
 122 else
 123         # Make sure we did not fall back on $arg^{tree} codepath
 124         # since we are not checking out from an arbitrary tree-ish,
 125         # but switching branches.
 126         if test '' != "$new"
 127         then
 128                 git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 ||
 129                 die "Cannot switch branch to a non-commit."
 130         fi
 131 fi
 132
 133 # We are switching branches and checking out trees, so
 134 # we *NEED* to be at the toplevel.
 135 cdup=$(git-rev-parse --show-cdup)
 136 if test ! -z "$cdup"
 137 then
 138         cd "$cdup"
 139 fi
 140
 141 [ -z "$new" ] && new=$old && new_name="$old_name"
 142
 143 # If we don't have an old branch that we're switching to,
 144 # and we don't have a new branch name for the target we
 145 # are switching to, then we'd better just be checking out
 146 # what we already had
 147
 148 [ -z "$branch$newbranch" ] &&
 149         [ "$new" != "$old" ] &&
 150         die "git checkout: provided reference cannot be checked out directly
 151
 152   You need -b to associate a new branch with the wanted checkout. Example:
 153   git checkout -b <new_branch_name> $arg
 154 "
 155
 156 if [ "X$old" = X ]
 157 then
 158         echo "warning: You do not appear to currently be on a branch." >&2
 159         echo "warning: Forcing checkout of $new_name." >&2
 160         force=1
 161 fi
 162
 163 if [ "$force" ]
 164 then
 165     git-read-tree --reset -u $new
 166 else
 167     git-update-index --refresh >/dev/null
 168     merge_error=$(git-read-tree -m -u --exclude-per-directory=.gitignore $old $new 2>&1) || (
 169         case "$merge" in
 170         '')
 171                 echo >&2 "$merge_error"
 172                 exit 1 ;;
 173         esac
 174
 175         # Match the index to the working tree, and do a three-way.
 176         git diff-files --name-only | git update-index --remove --stdin &&
 177         work=`git write-tree` &&
 178         git read-tree --reset -u $new &&
 179         git read-tree -m -u --aggressive --exclude-per-directory=.gitignore $old $new $work ||
 180         exit
 181
 182         if result=`git write-tree 2>/dev/null`
 183         then
 184             echo >&2 "Trivially automerged."
 185         else
 186             git merge-index -o git-merge-one-file -a
 187         fi
 188
 189         # Do not register the cleanly merged paths in the index yet.
 190         # this is not a real merge before committing, but just carrying
 191         # the working tree changes along.
 192         unmerged=`git ls-files -u`
 193         git read-tree --reset $new
 194         case "$unmerged" in
 195         '')     ;;
 196         *)
 197                 (
 198                         z40=0000000000000000000000000000000000000000
 199                         echo "$unmerged" |
 200                         sed -e 's/^[0-7]* [0-9a-f]* /'"0 $z40 /"
 201                         echo "$unmerged"
 202                 ) | git update-index --index-info
 203                 ;;
 204         esac
 205         exit 0
 206     )
 207     saved_err=$?
 208     if test "$saved_err" = 0
 209     then
 210         test "$new" = "$old" || git diff-index --name-status "$new"
 211     fi
 212     (exit $saved_err)
 213 fi
 214
 215 #
 216 # Switch the HEAD pointer to the new branch if we
 217 # checked out a branch head, and remove any potential
 218 # old MERGE_HEAD's (subsequent commits will clearly not
 219 # be based on them, since we re-set the index)
 220 #
 221 if [ "$?" -eq 0 ]; then
 222         if [ "$newbranch" ]; then
 223                 if [ "$newbranch_log" ]; then
 224                         mkdir -p $(dirname "$GIT_DIR/logs/refs/heads/$newbranch")
 225                         touch "$GIT_DIR/logs/refs/heads/$newbranch"
 226                 fi
 227                 git-update-ref -m "checkout: Created from $new_name" "refs/heads/$newbranch" $new || exit
 228                 branch="$newbranch"
 229         fi
 230         [ "$branch" ] &&
 231         GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
 232         rm -f "$GIT_DIR/MERGE_HEAD"
 233 else
 234         exit 1
 235 fi