git-describe: Die early if there are no possible descriptions

diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index 0897b5971a770755527817d4cb3766d87ce5bebd..37e044db40bb89470bb64a4108c86d5173e03b5a 100755 (executable)
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -40,6 +40,16 @@ skip_commit()
        done;
 }
 
+# if you run 'git_commit_non_empty_tree "$@"' in a commit filter,
+# it will skip commits that leave the tree untouched, commit the other.
+git_commit_non_empty_tree()
+{
+       if test $# = 3 && test "$1" = $(git rev-parse "$3^{tree}"); then
+               map "$3"
+       else
+               git commit-tree "$@"
+       fi
+}
 # override die(): this version puts in an extra line break, so that
 # the progress is still visible
 
@@ -109,11 +119,12 @@ filter_tree=
 filter_index=
 filter_parent=
 filter_msg=cat
-filter_commit='git commit-tree "$@"'
+filter_commit=
 filter_tag_name=
 filter_subdir=
 orig_namespace=refs/original/
 force=
+prune_empty=
 while :
 do
        case "$1" in
@@ -126,6 +137,11 @@ do
                force=t
                continue
                ;;
+       --prune-empty)
+               shift
+               prune_empty=t
+               continue
+               ;;
        -*)
                ;;
        *)
@@ -176,6 +192,17 @@ do
        esac
 done
 
+case "$prune_empty,$filter_commit" in
+,)
+       filter_commit='git commit-tree "$@"';;
+t,)
+       filter_commit="$functions;"' git_commit_non_empty_tree "$@"';;
+,*)
+       ;;
+*)
+       die "Cannot set --prune-empty and --filter-commit at the same time"
+esac
+
 case "$force" in
 t)
        rm -rf "$tempdir"
@@ -193,13 +220,21 @@ die ""
 # Remove tempdir on exit
 trap 'cd ../..; rm -rf "$tempdir"' 0
 
+ORIG_GIT_DIR="$GIT_DIR"
+ORIG_GIT_WORK_TREE="$GIT_WORK_TREE"
+ORIG_GIT_INDEX_FILE="$GIT_INDEX_FILE"
+GIT_WORK_TREE=.
+export GIT_DIR GIT_WORK_TREE
+
 # Make sure refs/original is empty
-git for-each-ref > "$tempdir"/backup-refs
+git for-each-ref > "$tempdir"/backup-refs || exit
 while read sha1 type name
 do
        case "$force,$name" in
        ,$orig_namespace*)
-               die "Namespace $orig_namespace not empty"
+               die "Cannot create a new backup.
+A previous backup already exists in $orig_namespace
+Force overwriting the backup with -f"
        ;;
        t,$orig_namespace*)
                git update-ref -d "$name" $sha1
@@ -207,15 +242,10 @@ do
        esac
 done < "$tempdir"/backup-refs
 
-ORIG_GIT_DIR="$GIT_DIR"
-ORIG_GIT_WORK_TREE="$GIT_WORK_TREE"
-ORIG_GIT_INDEX_FILE="$GIT_INDEX_FILE"
-GIT_WORK_TREE=.
-export GIT_DIR GIT_WORK_TREE
-
 # The refs should be updated if their heads were rewritten
-git rev-parse --no-flags --revs-only --symbolic-full-name --default HEAD "$@" |
-sed -e '/^^/d' >"$tempdir"/heads
+git rev-parse --no-flags --revs-only --symbolic-full-name \
+       --default HEAD "$@" > "$tempdir"/raw-heads || exit
+sed -e '/^^/d' "$tempdir"/raw-heads >"$tempdir"/heads
 
 test -s "$tempdir"/heads ||
        die "Which ref do you want to rewrite?"
@@ -224,8 +254,6 @@ GIT_INDEX_FILE="$(pwd)/../index"
 export GIT_INDEX_FILE
 git read-tree || die "Could not seed the index"
 
-ret=0
-
 # map old->new commit ids for rewriting parents
 mkdir ../map || die "Could not create map/ directory"
 
@@ -244,10 +272,10 @@ test $commits -eq 0 && die "Found nothing to rewrite"
 
 # Rewrite the commits
 
-i=0
+git_filter_branch__commit_count=0
 while read commit parents; do
-       i=$(($i+1))
-       printf "\rRewrite $commit ($i/$commits)"
+       git_filter_branch__commit_count=$(($git_filter_branch__commit_count+1))
+       printf "\rRewrite $commit ($git_filter_branch__commit_count/$commits)"
 
        case "$filter_subdir" in
        "")
@@ -288,10 +316,11 @@ while read commit parents; do
                        die "tree filter failed: $filter_tree"
 
                (
-                       git diff-index -r --name-only $commit
+                       git diff-index -r --name-only $commit &&
                        git ls-files --others
-               ) |
-               git update-index --add --replace --remove --stdin
+               ) > "$tempdir"/tree-state || exit
+               git update-index --add --replace --remove --stdin \
+                       < "$tempdir"/tree-state || exit
        fi
 
        eval "$filter_index" < /dev/null ||
@@ -312,7 +341,8 @@ while read commit parents; do
                eval "$filter_msg" > ../message ||
                        die "msg filter failed: $filter_msg"
        @SHELL_PATH@ -c "$filter_commit" "git commit-tree" \
-               $(git write-tree) $parentstr < ../message > ../map/$commit
+               $(git write-tree) $parentstr < ../message > ../map/$commit ||
+                       die "could not write rewritten commit"
 done <../revs
 
 # In case of a subdirectory filter, it is possible that a specified head
@@ -380,7 +410,8 @@ do
                        die "Could not rewrite $ref"
        ;;
        esac
-       git update-ref -m "filter-branch: backup" "$orig_namespace$ref" $sha1
+       git update-ref -m "filter-branch: backup" "$orig_namespace$ref" $sha1 ||
+                exit
 done < "$tempdir"/heads
 
 # TODO: This should possibly go, with the semantics that all positive given
@@ -399,7 +430,7 @@ if [ "$filter_tag_name" ]; then
                if [ "$type" = "tag" ]; then
                        # Dereference to a commit
                        sha1t="$sha1"
-                       sha1="$(git rev-parse "$sha1"^{commit} 2>/dev/null)" || continue
+                       sha1="$(git rev-parse -q "$sha1"^{commit})" || continue
                fi
 
                [ -f "../map/$sha1" ] || continue
@@ -456,7 +487,7 @@ test -z "$ORIG_GIT_INDEX_FILE" || {
 }
 
 if [ "$(is_bare_repository)" = false ]; then
-       git read-tree -u -m HEAD
+       git read-tree -u -m HEAD || exit
 fi
 
-exit $ret
+exit 0