git-gui: Guess our version accurately as a subproject.

[thirdparty/git.git] / GIT-VERSION-GEN

diff --git a/GIT-VERSION-GEN b/GIT-VERSION-GEN
index d3087489c584066c84b8c711a61d058f8ce24cfa..9fc80a656c19452fd90eb06207699b3bdd8de0a9 100755 (executable)
--- a/GIT-VERSION-GEN
+++ b/GIT-VERSION-GEN
@@ -6,12 +6,45 @@ DEF_VER=0.5.GIT
 LF='
 '
 
-# First try git-describe, then see if there is a version file
-# (included in release tarballs), then default
-if VN=$(git describe --abbrev=4 HEAD 2>/dev/null) &&
+tree_search ()
+{
+       head=$1
+       tree=$2
+       for p in $(git rev-list --parents --max-count=1 $head 2>/devnull)
+       do
+               test $tree = $(git rev-parse $p^{tree} 2>/dev/null) &&
+               vn=$(git describe --abbrev=4 $p 2>/dev/null) &&
+               case "$vn" in
+               gitgui-[0-9]*) echo $vn; break;;
+               esac
+       done
+}
+
+# We may be a subproject, so try looking for the merge
+# commit that supplied this directory content if we are
+# not at the toplevel.  We probably will always be the
+# second parent in the commit, but we shouldn't rely on
+# that fact.
+#
+# If we are at the toplevel or the merge assumption fails
+# try looking for a gitgui-* tag, or fallback onto the
+# distributed version file.
+
+if prefix="$(git rev-parse --show-prefix 2>/dev/null)"
+   test -n "$prefix" &&
+   head=$(git rev-list --max-count=1 HEAD -- . 2>/dev/null) &&
+   tree=$(git rev-parse --verify "HEAD:$prefix" 2>/dev/null) &&
+   VN=$(tree_search $head $tree)
+   case "$VN" in
+   gitgui-[0-9]*) : happy ;;
+   *) (exit 1) ;;
+   esac
+then
+       VN=$(echo "$VN" | sed -e 's/^gitgui-//;s/-/./g');
+elif VN=$(git describe --abbrev=4 HEAD 2>/dev/null) &&
    case "$VN" in
-   *$LF*) (exit 1) ;;
    gitgui-[0-9]*) : happy ;;
+   *) (exit 1) ;;
    esac
 then
        VN=$(echo "$VN" | sed -e 's/^gitgui-//;s/-/./g');