Speed up `which` by avoiding a loop

[code/vcsh.git] / vcsh

#!/bin/sh

# This program is licensed under the GNU GPL version 2 or later.
# (c) Richard "RichiH" Hartmann <richih@debian.org>, 2011-2015
# For details, see LICENSE. To submit patches, you have to agree to
# license your code under the GNU GPL version 2 or later.

# While the following is not legally binding, the author would like to
# explain the choice of GPLv2+ over GPLv3+.
# The author prefers GPLv3+ over GPLv2+ but feels it's better to maintain
# full compatibility's with Git. In case Git ever changes its licensing terms,
# which is admittedly extremely unlikely to the point of being impossible,
# this software will most likely follow suit.

# This should always be the first line of code to facilitate debugging
[ -n "$VCSH_DEBUG" ] && set -vx


# If '.git-HEAD' is appended to the version, you are seeing an unreleased
# version of vcsh; the master branch is supposed to be clean at all times
# so you can most likely just use it nonetheless
VERSION='1.20141026'
SELF=$(basename $0)

fatal() {
        echo "$SELF: fatal: $1" >&2
        [ -z $2 ] && exit 1
        exit $2
}

# We need to run getops as soon as possible so we catch -d and other
# options that will modify our behaviour.
# Commands are handled at the end of this script.
while getopts "c:dv" flag; do
        if [ x"$1" = x'-d' ] || [ x"$1" = x'--debug' ]; then
                set -vx
                VCSH_DEBUG=1
                echo "debug mode on"
                echo "$SELF $VERSION"
        elif [ x"$1" = x'-v' ]; then
                VCSH_VERBOSE=1
                echo "verbose mode on"
                echo "$SELF $VERSION"
        elif [ x"$1" = x'-c' ]; then
                VCSH_OPTION_CONFIG=$OPTARG
        fi
        shift 1
done

source_all() {
        # Source file even if it's in $PWD and does not have any slashes in it
        case $1 in
                */*) . "$1";;
                *)   . "$PWD/$1";;
        esac;
}


# Read configuration and set defaults if anything's not set
[ -n "$VCSH_DEBUG" ]                  && set -vx
: ${XDG_CONFIG_HOME:="$HOME/.config"}

# Read configuration files if there are any
[ -r "/etc/vcsh/config" ]             && . "/etc/vcsh/config"
[ -r "$XDG_CONFIG_HOME/vcsh/config" ] && . "$XDG_CONFIG_HOME/vcsh/config"
if [ -n "$VCSH_OPTION_CONFIG" ]; then
        # Source $VCSH_OPTION_CONFIG if it can be read and is in $PWD of $PATH
        if [ -r "$VCSH_OPTION_CONFIG" ]; then
                source_all "$VCSH_OPTION_CONFIG"
        else
                fatal "Can not read configuration file '$VCSH_OPTION_CONFIG'" 1
        fi
fi
[ -n "$VCSH_DEBUG" ]                  && set -vx

# Read defaults
: ${VCSH_REPO_D:="$XDG_CONFIG_HOME/vcsh/repo.d"}
: ${VCSH_HOOK_D:="$XDG_CONFIG_HOME/vcsh/hooks-enabled"}
: ${VCSH_OVERLAY_D:="$XDG_CONFIG_HOME/vcsh/overlays-enabled"}
: ${VCSH_BASE:="$HOME"}
: ${VCSH_GITIGNORE:=exact}
: ${VCSH_GITATTRIBUTES:=none}
: ${VCSH_WORKTREE:=absolute}

if [ ! "x$VCSH_GITIGNORE" = 'xexact' ] && [ ! "x$VCSH_GITIGNORE" = 'xnone' ] && [ ! "x$VCSH_GITIGNORE" = 'xrecursive' ]; then
        fatal "'\$VCSH_GITIGNORE' must equal 'exact', 'none', or 'recursive'" 1
fi

if [ ! "x$VCSH_WORKTREE" = 'xabsolute' ] && [ ! "x$VCSH_WORKTREE" = 'xrelative' ]; then
        fatal "'\$VCSH_WORKTREE' must equal 'absolute', or 'relative'" 1
fi


help() {
        echo "usage: $SELF <options> <command>

   options:
   -c <file>            Source file
   -d                   Enable debug mode
   -v                   Enable verbose mode

   commands:
   clone [-b <branch>] \\
         <remote> \\
         [<repo>]       Clone from an existing repository
   commit               Commit in all repositories
   delete <repo>        Delete an existing repository
   enter <repo>         Enter repository; spawn new instance of \$SHELL
   help                 Display this help text
   init <repo>          Initialize a new repository
   list                 List all repositories
   list-tracked \\
        [<repo>]        List all files tracked all or one repositories
   list-untracked \\
        [<-r>] [<repo>] List all files not tracked by all or one repositories
   pull                 Pull from all vcsh remotes
   push                 Push to vcsh remotes
   rename <repo> \\
          <newname>     Rename repository
   run <repo> \\
       <command>        Use this repository
   status \\
     [--terse] [<repo>] Show statuses of all/one vcsh repositories
   upgrade <repo>       Upgrade repository to currently recommended settings
   version              Print version information
   which <substring>    Find substring in name of any tracked file
   write-gitignore \\
   <repo>               Write .gitignore.d/<repo> via git ls-files

   <repo> <git command> Shortcut to run git commands directly
   <repo>               Shortcut to enter repository" >&2
}

debug() {
        [ -n "$VCSH_DEBUG" ] && echo "$SELF: debug: $@"
}

verbose() {
        if [ -n "$VCSH_DEBUG" ] || [ -n "$VCSH_VERBOSE" ]; then echo "$SELF: verbose: $@"; fi
}

error() {
        echo "$SELF: error: $1" >&2
}

info() {
        echo "$SELF: info: $1"
}

clone() {
        hook pre-clone
        init
        git remote add origin "$GIT_REMOTE"
        git checkout -b "$VCSH_BRANCH" || return $?
        git config branch."$VCSH_BRANCH".remote origin
        git config branch."$VCSH_BRANCH".merge  refs/heads/"$VCSH_BRANCH"
        if [ $(git ls-remote origin "$VCSH_BRANCH" 2> /dev/null | wc -l ) -lt 1 ]; then
                info "remote is empty, not merging anything.
  You should add files to your new repository."
                exit
        fi
        git fetch origin "$VCSH_BRANCH"
        hook pre-merge
        git ls-tree -r --name-only origin/"$VCSH_BRANCH" | (while read object; do
                [ -e "$object" ] &&
                        error "'$object' exists." &&
                        VCSH_CONFLICT=1
        done
        [ x"$VCSH_CONFLICT" = x'1' ]) &&
                fatal "will stop after fetching and not try to merge!
  Once this situation has been resolved, run 'vcsh $VCSH_REPO_NAME pull' to finish cloning." 17
        git merge origin/"$VCSH_BRANCH"
        hook post-merge
        hook post-clone
        retire
        hook post-clone-retired
}

commit() {
        hook pre-commit
        for VCSH_REPO_NAME in $(list); do
                echo "$VCSH_REPO_NAME: "
                GIT_DIR=$VCSH_REPO_D/$VCSH_REPO_NAME.git; export GIT_DIR
                use
                git commit --untracked-files=no --quiet
                VCSH_COMMAND_RETURN_CODE=$?
                echo
        done
        hook post-commit
}

delete() {
        cd "$VCSH_BASE" || fatal "could not enter '$VCSH_BASE'" 11
        use
        info "This operation WILL DESTROY DATA!"
        files=$(git ls-files)
        echo "These files will be deleted:

$files

AGAIN, THIS WILL DELETE YOUR DATA!
To continue, type 'Yes, do as I say'"
        read answer
        [ "x$answer" = 'xYes, do as I say' ] || exit 16
        for file in $files; do
                rm -f $file || info "could not delete '$file', continuing with deletion"
        done
        rm -rf "$GIT_DIR" || error "could not delete '$GIT_DIR'"
}

enter() {
        hook pre-enter
        use
        $SHELL
        hook post-enter
}

git_dir_exists() {
        [ -d "$GIT_DIR" ] || fatal "no repository found for '$VCSH_REPO_NAME'" 12
}

hook() {
        for hook in "$VCSH_HOOK_D/$1"* "$VCSH_HOOK_D/$VCSH_REPO_NAME.$1"*; do
                [ -x "$hook" ] || continue
                verbose "executing '$hook'"
                "$hook"
        done
}

init() {
        hook pre-init
        [ ! -e "$GIT_DIR" ] || fatal "'$GIT_DIR' exists" 10
        mkdir -p "$VCSH_BASE" || fatal "could not create '$VCSH_BASE'" 50
        cd "$VCSH_BASE" || fatal "could not enter '$VCSH_BASE'" 11
        git init --shared=0600
        upgrade
        hook post-init
}

list() {
        for repo in "$VCSH_REPO_D"/*.git; do
                [ -d "$repo" ] && [ -r "$repo" ] && echo "$(basename "$repo" .git)"
        done
}

get_files() {
        GIT_DIR=$VCSH_REPO_D/$VCSH_REPO_NAME.git; export GIT_DIR
        git ls-files
}

list_tracked() {
        VCSH_REPO_NAME=$2; export VCSH_REPO_NAME
        if [ -n "$VCSH_REPO_NAME" ]; then
                get_files | list_tracked_helper
        else
                for VCSH_REPO_NAME in $(list); do
                        get_files
                done | list_tracked_helper
        fi
}

list_tracked_helper() {
        sed "s,^,$(printf '%s\n' "$VCSH_BASE/" | sed 's/[,\&]/\\&/g')," | sort -u
}

list_tracked_by() {
        list_tracked $2
}

list_untracked() {
        command -v 'comm' >/dev/null 2>&1 || fatal "Could not find 'comm'"

        temp_file_others=$(mktemp "${TMPDIR:-/tmp}/tmp.XXXXXXXXXX") || fatal 'Could not create temp file'
        temp_file_untracked=$(mktemp "${TMPDIR:-/tmp}/tmp.XXXXXXXXXX") || fatal 'Could not create temp file'
        temp_file_untracked_copy=$(mktemp "${TMPDIR:-/tmp}/tmp.XXXXXXXXXX") || fatal 'Could not create temp file'

        # Hack in support for `vcsh list-untracked -r`...
        directory_opt="--directory"
        shift 1
        while getopts "r" flag; do
                if [ x"$1" = x'-r' ]; then
                        unset directory_opt
                fi
                shift 1
        done
        # ...and parse for a potential parameter afterwards. As we shifted things out of $* in during getops, we need to look at $1
        VCSH_REPO_NAME=$1; export VCSH_REPO_NAME

        if [ -n "$VCSH_REPO_NAME" ]; then
                list_untracked_helper $VCSH_REPO_NAME
        else
                for VCSH_REPO_NAME in $(list); do
                        list_untracked_helper $VCSH_REPO_NAME
                done
        fi
        cat $temp_file_untracked

        unset directory_opt directory_component
        rm -f $temp_file_others $temp_file_untracked $temp_file_untracked_copy || fatal 'Could not delete temp files'
}

list_untracked_helper() {
        export GIT_DIR="$VCSH_REPO_D/$VCSH_REPO_NAME.git"
        git ls-files --others "$directory_opt" | (
                while read line; do
                        echo "$line"
                        directory_component=${line%%/*}
                        [ -d "$directory_component" ] && printf '%s/\n' "$directory_component"
                done
                ) | sort -u > $temp_file_others
        if [ -z "$ran_once" ]; then
                ran_once=1
                cp $temp_file_others $temp_file_untracked || fatal 'Could not copy temp file'
        fi
        cp $temp_file_untracked $temp_file_untracked_copy || fatal 'Could not copy temp file'
        comm -12 $temp_file_others $temp_file_untracked_copy > $temp_file_untracked
}

pull() {
        hook pre-pull
        for VCSH_REPO_NAME in $(list); do
                printf '%s: ' "$VCSH_REPO_NAME"
                GIT_DIR=$VCSH_REPO_D/$VCSH_REPO_NAME.git; export GIT_DIR
                use
                git pull
                VCSH_COMMAND_RETURN_CODE=$?
                echo
        done
        hook post-pull
}

push() {
        hook pre-push
        for VCSH_REPO_NAME in $(list); do
                printf '%s: ' "$VCSH_REPO_NAME"
                GIT_DIR=$VCSH_REPO_D/$VCSH_REPO_NAME.git; export GIT_DIR
                use
                git push
                VCSH_COMMAND_RETURN_CODE=$?
                echo
        done
        hook post-push
}

retire() {
        unset VCSH_DIRECTORY
}

rename() {
        git_dir_exists
        [ -d "$GIT_DIR_NEW" ] && fatal "'$GIT_DIR_NEW' exists" 54
        mv -f "$GIT_DIR" "$GIT_DIR_NEW" || fatal "Could not mv '$GIT_DIR' '$GIT_DIR_NEW'" 52

        # Now that the repository has been renamed, we need to fix up its configuration
        # Overwrite old name..
        GIT_DIR=$GIT_DIR_NEW
        VCSH_REPO_NAME=$VCSH_REPO_NAME_NEW
        # ..and clobber all old configuration
        upgrade
}

run() {
        hook pre-run
        use
        "$@"
        VCSH_COMMAND_RETURN_CODE=$?
        hook post-run
}

status() {
        if [ -t 1 ]; then
                COLORING="-c color.status=always"
        fi
        if [ -n "$VCSH_REPO_NAME" ]; then
                status_helper $VCSH_REPO_NAME
        else
                for VCSH_REPO_NAME in $(list); do
                        STATUS=$(status_helper $VCSH_REPO_NAME "$COLORING")
                        [ -n "$STATUS" -o -z "$VCSH_STATUS_TERSE" ] && echo "$VCSH_REPO_NAME:"
                        [ -n "$STATUS" ]            && echo "$STATUS"
                        [ -z "$VCSH_STATUS_TERSE" ] && echo
                done
        fi
}

status_helper() {
        GIT_DIR=$VCSH_REPO_D/$1.git; export GIT_DIR
        VCSH_GIT_OPTIONS=$2
        use
        remote_tracking_branch=$(git rev-parse --abbrev-ref --symbolic-full-name @{u} 2> /dev/null) && {
                commits_behind=$(git log ..${remote_tracking_branch} --oneline | wc -l)
                commits_ahead=$(git log ${remote_tracking_branch}.. --oneline | wc -l)
                [ ${commits_behind} -ne 0 ] && echo "Behind $remote_tracking_branch by $commits_behind commits"
                [ ${commits_ahead} -ne 0 ] && echo "Ahead of $remote_tracking_branch by $commits_ahead commits"
        }
        git ${VCSH_GIT_OPTIONS} status --short --untracked-files='no'
        VCSH_COMMAND_RETURN_CODE=$?
}

upgrade() {
        hook pre-upgrade
        # fake-bare repositories are not bare, actually. Set this to false
        # because otherwise Git complains "fatal: core.bare and core.worktree
        # do not make sense"
        git config core.bare false
        # core.worktree may be absolute or relative to $GIT_DIR, depending on
        # user preference
        if [ ! "x$VCSH_WORKTREE" = 'xabsolute' ]; then
                git config core.worktree "$(cd "$GIT_DIR" && GIT_WORK_TREE=$VCSH_BASE git rev-parse --show-cdup)"
        elif [ ! "x$VCSH_WORKTREE" = 'xrelative' ]; then
                git config core.worktree "$VCSH_BASE"
        fi
        [ ! "x$VCSH_GITIGNORE" = 'xnone' ] && git config core.excludesfile ".gitignore.d/$VCSH_REPO_NAME"
        [ ! "x$VCSH_GITATTRIBUTES" = 'xnone' ] && git config core.attributesfile ".gitattributes.d/$VCSH_REPO_NAME"
        git config vcsh.vcsh 'true'
        use
        [ -e "$VCSH_BASE/.gitignore.d/$VCSH_REPO_NAME" ] && git add -f "$VCSH_BASE/.gitignore.d/$VCSH_REPO_NAME"
        [ -e "$VCSH_BASE/.gitattributes.d/$VCSH_REPO_NAME" ] && git add -f "$VCSH_BASE/.gitattributes.d/$VCSH_REPO_NAME"
        hook post-upgrade
}

use() {
        git_dir_exists
        VCSH_DIRECTORY=$VCSH_REPO_NAME; export VCSH_DIRECTORY
}

which() {
        [ -e "$VCSH_COMMAND_PARAMETER" ] || fatal "'$VCSH_COMMAND_PARAMETER' does not exist" 1
        for VCSH_REPO_NAME in $(list); do
                get_files | grep -- "$VCSH_COMMAND_PARAMETER" | sed "s/^/$VCSH_REPO_NAME: /"
        done | sort -u
}

write_gitignore() {
        # Don't do anything if the user does not want to write gitignore
        if [ "x$VCSH_GITIGNORE" = 'xnone' ]; then
                info "Not writing gitignore as '\$VCSH_GITIGNORE' is set to 'none'"
                exit
        fi

        use
        cd "$VCSH_BASE" || fatal "could not enter '$VCSH_BASE'" 11
        OLDIFS=$IFS
        IFS=$(printf '\n\t')
        gitignores=$(for file in $(git ls-files); do
                while true; do
                        echo "$file"; new=${file%/*}
                        [ x"$file" = x"$new" ] && break
                        file=$new
                done;
        done | sort -u)

        # Contrary to GNU mktemp, mktemp on BSD/OSX requires a template for temp files
        # Using a template makes GNU mktemp default to $PWD and not #TMPDIR for tempfile location
        # To make every OS happy, set full path explicitly
        tempfile=$(mktemp "${TMPDIR:-/tmp}/tmp.XXXXXXXXXX") || fatal "could not create tempfile: '${tempfile}'" 51

        echo '*' > "$tempfile" || fatal "could not write to '$tempfile'" 57
        for gitignore in $gitignores; do
                echo "$gitignore" | sed 's@^@!/@' >> "$tempfile" || fatal "could not write to '$tempfile'" 57
                if [ "x$VCSH_GITIGNORE" = 'xrecursive' ] && [ -d "$gitignore" ]; then
                        { echo "$gitignore/*" | sed 's@^@!/@' >> "$tempfile" || fatal "could not write to '$tempfile'" 57; }
                fi
        done
        IFS=$OLDIFS
        if diff -N "$tempfile" "$VCSH_BASE/.gitignore.d/$VCSH_REPO_NAME" > /dev/null; then
                rm -f "$tempfile" || error "could not delete '$tempfile'"
                exit
        fi
        if [ -e "$VCSH_BASE/.gitignore.d/$VCSH_REPO_NAME" ]; then
                info "'$VCSH_BASE/.gitignore.d/$VCSH_REPO_NAME' differs from new data, moving it to '$VCSH_BASE/.gitignore.d/$VCSH_REPO_NAME.bak'"
                mv -f "$VCSH_BASE/.gitignore.d/$VCSH_REPO_NAME" "$VCSH_BASE/.gitignore.d/$VCSH_REPO_NAME.bak" ||
                        fatal "could not move '$VCSH_BASE/.gitignore.d/$VCSH_REPO_NAME' to '$VCSH_BASE/.gitignore.d/$VCSH_REPO_NAME.bak'" 53
        fi
        mv -f "$tempfile" "$VCSH_BASE/.gitignore.d/$VCSH_REPO_NAME" ||
                fatal "could not move '$tempfile' to '$VCSH_BASE/.gitignore.d/$VCSH_REPO_NAME'" 53
}

debug $(git version)

if [ ! "x$VCSH_GITIGNORE" = 'xexact' ] && [ ! "x$VCSH_GITIGNORE" = 'xnone' ] && [ ! "x$VCSH_GITIGNORE" = 'xrecursive' ]; then
        fatal "'\$VCSH_GITIGNORE' must equal 'exact', 'none', or 'recursive'" 1
fi

VCSH_COMMAND=$1; export VCSH_COMMAND

case $VCSH_COMMAND in
        clon|clo|cl) VCSH_COMMAND=clone;;
        commi|comm|com|co) VCSH_COMMAND=commit;;
        delet|dele|del|de) VCSH_COMMAND=delete;;
        ente|ent|en) VCSH_COMMAND=enter;;
        hel|he) VCSH_COMMAND=help;;
        ini|in) VCSH_COMMAND=init;;
        pul) VCSH_COMMAND=pull;;
        pus) VCSH_COMMAND=push;;
        renam|rena|ren|re) VCSH_COMMAND=rename;;
        ru) VCSH_COMMAND=run;;
        statu|stat|sta|st) VCSH_COMMAND=status;;
        upgrad|upgra|upgr|up) VCSH_COMMAND=upgrade;;
        versio|versi|vers|ver|ve) VCSH_COMMAND=version;;
        which|whi|wh) VCSH_COMMAND=which;;
        write|writ|wri|wr) VCSH_COMMAND=write-gitignore;;
esac    

if [ x"$VCSH_COMMAND" = x'clone' ]; then
        VCSH_BRANCH=
        if [ "$2" = -b ]; then
                VCSH_BRANCH=$3
                shift
                shift
        fi
        [ -z "$2" ] && fatal "$VCSH_COMMAND: please specify a remote" 1
        GIT_REMOTE="$2"
        [ -n "$VCSH_BRANCH" ] || if [ "$3" = -b ]; then
                VCSH_BRANCH=$4
                shift
                shift
        fi
        if [ -n "$3" ]; then
                VCSH_REPO_NAME=$3
                [ -z "$VCSH_BRANCH" ] && [ "$4" = -b ] && VCSH_BRANCH=$5
        else
                VCSH_REPO_NAME=$(basename "${GIT_REMOTE#*:}" .git)
        fi
        [ -z "$VCSH_REPO_NAME" ] && fatal "$VCSH_COMMAND: could not determine repository name" 1
        export VCSH_REPO_NAME
        [ -n "$VCSH_BRANCH" ] || VCSH_BRANCH=master
        GIT_DIR=$VCSH_REPO_D/$VCSH_REPO_NAME.git; export GIT_DIR
elif [ "$VCSH_COMMAND" = 'version' ]; then
        echo "$SELF $VERSION"
        git version
        exit
elif [ x"$VCSH_COMMAND" = x'which' ]; then
        [ -z "$2" ] && fatal "$VCSH_COMMAND: please specify a filename" 1
        [ -n "$3" ] && fatal "$VCSH_COMMAND: too many parameters" 1
        VCSH_COMMAND_PARAMETER=$2; export VCSH_COMMAND_PARAMETER
elif [ x"$VCSH_COMMAND" = x'delete' ]           ||
     [ x"$VCSH_COMMAND" = x'enter' ]            ||
     [ x"$VCSH_COMMAND" = x'init' ]             ||
     [ x"$VCSH_COMMAND" = x'list-tracked-by' ]  ||
     [ x"$VCSH_COMMAND" = x'rename' ]           ||
     [ x"$VCSH_COMMAND" = x'run' ]              ||
     [ x"$VCSH_COMMAND" = x'upgrade' ]          ||
     [ x"$VCSH_COMMAND" = x'write-gitignore' ]; then
        [ -z "$2" ]                                     && fatal "$VCSH_COMMAND: please specify repository to work on" 1
        [ x"$VCSH_COMMAND" = x'rename' ] && [ -z "$3" ] && fatal "$VCSH_COMMAND: please specify a target name" 1
        [ x"$VCSH_COMMAND" = x'run'    ] && [ -z "$3" ] && fatal "$VCSH_COMMAND: please specify a command" 1
        VCSH_REPO_NAME=$2; export VCSH_REPO_NAME
        GIT_DIR=$VCSH_REPO_D/$VCSH_REPO_NAME.git; export GIT_DIR
        [ x"$VCSH_COMMAND" = x'rename' ] && { VCSH_REPO_NAME_NEW=$3; export VCSH_REPO_NAME_NEW;
                                              GIT_DIR_NEW=$VCSH_REPO_D/$VCSH_REPO_NAME_NEW.git; export GIT_DIR_NEW; }
        [ x"$VCSH_COMMAND" = x'run' ]    && shift 2
elif [ x"$VCSH_COMMAND" = x'commit' ] ||
     [ x"$VCSH_COMMAND" = x'list'   ] ||
     [ x"$VCSH_COMMAND" = x'list-tracked' ] ||
     [ x"$VCSH_COMMAND" = x'list-untracked' ] ||
     [ x"$VCSH_COMMAND" = x'pull'   ] ||
     [ x"$VCSH_COMMAND" = x'push'   ]; then
        :
elif [ x"$VCSH_COMMAND" = x'status' ]; then
        if [ x"$2" = x'--terse' ]; then
                VCSH_STATUS_TERSE=1; export VCSH_STATUS_TERSE
                shift
        fi
        VCSH_REPO_NAME=$2; export VCSH_REPO_NAME
elif [ -n "$2" ]; then
        VCSH_COMMAND='run'; export VCSH_COMMAND
        VCSH_REPO_NAME=$1; export VCSH_REPO_NAME
        GIT_DIR=$VCSH_REPO_D/$VCSH_REPO_NAME.git; export GIT_DIR
        [ -d "$GIT_DIR" ] || { help; exit 1; }
        shift 1
        set -- "git" "$@"
elif [ -n "$VCSH_COMMAND" ]; then
        VCSH_COMMAND='enter'; export VCSH_COMMAND
        VCSH_REPO_NAME=$1; export VCSH_REPO_NAME
        GIT_DIR=$VCSH_REPO_D/$VCSH_REPO_NAME.git; export GIT_DIR
        [ -d "$GIT_DIR" ] || { help; exit 1; }
else
        # $1 is empty, or 'help'
        help && exit
fi

# Did we receive a directory instead of a name?
# Mangle the input to fit normal operation.
if echo "$VCSH_REPO_NAME" | grep -q '/'; then
        GIT_DIR=$VCSH_REPO_NAME; export GIT_DIR
        VCSH_REPO_NAME=$(basename "$VCSH_REPO_NAME" .git); export VCSH_REPO_NAME
fi

check_dir() {
        check_directory="$1"
        if [ ! -d "$check_directory" ]; then
                if [ -e "$check_directory" ]; then
                        fatal "'$check_directory' exists but is not a directory" 13
                else
                        verbose "attempting to create '$check_directory'"
                        mkdir -p "$check_directory" || fatal "could not create '$check_directory'" 50
                fi
        fi
}

check_dir "$VCSH_REPO_D"
[ ! "x$VCSH_GITIGNORE" = 'xnone' ] && check_dir "$VCSH_BASE/.gitignore.d"
[ ! "x$VCSH_GITATTRIBUTES" = 'xnone' ] && check_dir "$VCSH_BASE/.gitattributes.d"

verbose "$VCSH_COMMAND begin"
VCSH_COMMAND=$(echo "$VCSH_COMMAND" | sed 's/-/_/g'); export VCSH_COMMAND

# Source repo-specific configuration file
[ -r "$XDG_CONFIG_HOME/vcsh/config.d/$VCSH_REPO_NAME" ] && . "$XDG_CONFIG_HOME/vcsh/config.d/$VCSH_REPO_NAME"

# source overlay functions
for overlay in "$VCSH_OVERLAY_D/$VCSH_COMMAND"* "$VCSH_OVERLAY_D/$VCSH_REPO_NAME.$VCSH_COMMAND"*; do
        [ -r "$overlay" ] || continue
        info "sourcing '$overlay'"
        . "$overlay"
done

hook pre-command
$VCSH_COMMAND "$@"
hook post-command
verbose "$VCSH_COMMAND end, exiting"
exit $VCSH_COMMAND_RETURN_CODE