Fix crash when reading the empty tree

diff --git a/git-bisect.sh b/git-bisect.sh
index 1ab2f187dcfd1ab9b81bbc3ebb3605601b4d29f0..03df1433ef12014584f23f16e65124c219c2f466 100755 (executable)
--- a/git-bisect.sh
+++ b/git-bisect.sh
@@ -1,9 +1,7 @@
 #!/bin/sh
-. git-sh-setup || dir "Not a git archive"
 
-usage() {
-    echo >&2 'usage: git bisect [start|bad|good|next|reset|visualize]
-git bisect start               reset bisect state and start bisection.
+USAGE='[start|bad|good|next|reset|visualize]'
+LONG_USAGE='git bisect start [<pathspec>]      reset bisect state and start bisection.
 git bisect bad [<rev>]         mark <rev> a known-bad revision.
 git bisect good [<rev>...]     mark <rev>... known-good revisions.
 git bisect next                        find next bisection to test and check it out.
@@ -11,7 +9,17 @@ git bisect reset [<branch>]   finish bisection search and go back to branch.
 git bisect visualize            show bisect status in gitk.
 git bisect replay <logfile>    replay bisection log
 git bisect log                 show bisect log.'
-    exit 1
+
+. git-sh-setup
+
+sq() {
+       perl -e '
+               for (@ARGV) {
+                       s/'\''/'\'\\\\\'\''/g;
+                       print " '\''$_'\''";
+               }
+               print "\n";
+       ' "$@"
 }
 
 bisect_autostart() {
@@ -33,7 +41,6 @@ bisect_autostart() {
 }
 
 bisect_start() {
-        case "$#" in 0) ;; *) usage ;; esac
        #
        # Verify HEAD. If we were bisecting before this, reset to the
        # top-of-line master first!
@@ -42,9 +49,16 @@ bisect_start() {
        die "Bad HEAD - I need a symbolic ref"
        case "$head" in
        refs/heads/bisect*)
-               git checkout master || exit
+               if [ -s "$GIT_DIR/head-name" ]; then
+                   branch=`cat "$GIT_DIR/head-name"`
+               else
+                   branch=master
+               fi
+               git checkout $branch || exit
                ;;
        refs/heads/*)
+               [ -s "$GIT_DIR/head-name" ] && die "won't bisect on seeked tree"
+               echo "$head" | sed 's#^refs/heads/##' >"$GIT_DIR/head-name"
                ;;
        *)
                die "Bad HEAD - strange symbolic ref"
@@ -57,7 +71,11 @@ bisect_start() {
        rm -f "$GIT_DIR/refs/heads/bisect"
        rm -rf "$GIT_DIR/refs/bisect/"
        mkdir "$GIT_DIR/refs/bisect"
-       echo "git-bisect start" >"$GIT_DIR/BISECT_LOG"
+       {
+           printf "git-bisect start"
+           sq "$@"
+       } >"$GIT_DIR/BISECT_LOG"
+       sq "$@" >"$GIT_DIR/BISECT_NAMES"
 }
 
 bisect_bad() {
@@ -121,7 +139,7 @@ bisect_next() {
        bad=$(git-rev-parse --verify refs/bisect/bad) &&
        good=$(git-rev-parse --sq --revs-only --not \
                $(cd "$GIT_DIR" && ls refs/bisect/good-*)) &&
-       rev=$(eval "git-rev-list --bisect $good $bad") || exit
+       rev=$(eval "git-rev-list --bisect $good $bad -- $(cat $GIT_DIR/BISECT_NAMES)") || exit
        if [ -z "$rev" ]; then
            echo "$bad was both good and bad"
            exit 1
@@ -131,7 +149,7 @@ bisect_next() {
            git-diff-tree --pretty $rev
            exit 0
        fi
-       nr=$(eval "git-rev-list $rev $good" | wc -l) || exit
+       nr=$(eval "git-rev-list $rev $good -- $(cat $GIT_DIR/BISECT_NAMES)" | wc -l) || exit
        echo "Bisecting: $nr revisions left to test after this"
        echo "$rev" > "$GIT_DIR/refs/heads/new-bisect"
        git checkout new-bisect || exit
@@ -142,12 +160,17 @@ bisect_next() {
 
 bisect_visualize() {
        bisect_next_check fail
-       gitk bisect/bad --not `cd "$GIT_DIR/refs" && echo bisect/good-*`
+       not=`cd "$GIT_DIR/refs" && echo bisect/good-*`
+       eval gitk bisect/bad --not $not -- $(cat "$GIT_DIR/BISECT_NAMES")
 }
 
 bisect_reset() {
        case "$#" in
-       0) branch=master ;;
+       0) if [ -s "$GIT_DIR/head-name" ]; then
+              branch=`cat "$GIT_DIR/head-name"`
+          else
+              branch=master
+          fi ;;
        1) test -f "$GIT_DIR/refs/heads/$1" || {
               echo >&2 "$1 does not seem to be a valid branch"
               exit 1
@@ -158,8 +181,9 @@ bisect_reset() {
        esac
        git checkout "$branch" &&
        rm -fr "$GIT_DIR/refs/bisect"
-       rm -f "$GIT_DIR/refs/heads/bisect"
+       rm -f "$GIT_DIR/refs/heads/bisect" "$GIT_DIR/head-name"
        rm -f "$GIT_DIR/BISECT_LOG"
+       rm -f "$GIT_DIR/BISECT_NAMES"
 }
 
 bisect_replay () {
@@ -173,7 +197,8 @@ bisect_replay () {
                test "$bisect" = "git-bisect" || continue
                case "$command" in
                start)
-                       bisect_start
+                       cmd="bisect_start $rev"
+                       eval "$cmd"
                        ;;
                good)
                        echo "$rev" >"$GIT_DIR/refs/bisect/good-$rev"