git-gui: New Git version check support routine

diff --git a/GIT-VERSION-GEN b/GIT-VERSION-GEN
index 79f1c527ffbf157d2314703ad4140bddaab24470..9770b0bc27ae4dfd44f4bfcfc74946fabefdc127 100755 (executable)
--- a/GIT-VERSION-GEN
+++ b/GIT-VERSION-GEN
@@ -1,29 +1,65 @@
 #!/bin/sh
 
 GVF=GIT-VERSION-FILE
-DEF_VER=v0.5.GIT
+DEF_VER=0.8.GITGUI
 
 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>/dev/null)
+       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 $vn; break;;
+               esac
+       done
+}
+
+# Always use the tarball version file if found, just
+# in case we are somehow contained in a larger git
+# repository that doesn't actually track our state.
+# (At least one package manager is doing this.)
+#
+# We may be a subproject, so try looking for the merge
+# commit that supplied this directory content if we are
+# not at the toplevel.  We probably will always be the
+# second parent in the commit, but we shouldn't rely on
+# that fact.
+#
+# If we are at the toplevel or the merge assumption fails
+# try looking for a gitgui-* tag.
+
+if test -f version &&
+   VN=$(cat version)
+then
+       : happy
+elif 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
-   *$LF*) (exit 1) ;;
-   v[0-9]*) : happy ;;
+   gitgui-[0-9]*) : happy ;;
+   *) (exit 1) ;;
    esac
 then
-       VN=$(echo "$VN" | sed -e 's/-/./g');
-elif test -f version
+       VN=$(echo "$VN" | sed -e 's/^gitgui-//;s/-/./g');
+elif VN=$(git describe --abbrev=4 HEAD 2>/dev/null) &&
+   case "$VN" in
+   gitgui-[0-9]*) : happy ;;
+   *) (exit 1) ;;
+   esac
 then
-       VN=$(cat version) || VN="$DEF_VER"
+       VN=$(echo "$VN" | sed -e 's/^gitgui-//;s/-/./g');
 else
        VN="$DEF_VER"
 fi
 
-VN=$(expr "$VN" : v*'\(.*\)')
-
 dirty=$(sh -c 'git diff-index --name-only HEAD' 2>/dev/null) || dirty=
 case "$dirty" in
 '')
@@ -34,13 +70,11 @@ esac
 
 if test -r $GVF
 then
-       VC=$(sed -e 's/^GIT_VERSION = //' <$GVF)
+       VC=$(sed -e 's/^GITGUI_VERSION = //' <$GVF)
 else
        VC=unset
 fi
 test "$VN" = "$VC" || {
-       echo >&2 "GIT_VERSION = $VN"
-       echo "GIT_VERSION = $VN" >$GVF
+       echo >&2 "GITGUI_VERSION = $VN"
+       echo "GITGUI_VERSION = $VN" >$GVF
 }
-
-