git-gui: Better handling of detached HEAD

If the current branch is not a symbolic-ref that points to a
name in the refs/heads/ namespace we now just assume that the
head is a detached head.  In this case we return the special
branch name of HEAD rather than empty string, as HEAD is a
valid revision specification and the empty string is not.

I have also slightly improved the current-branch function by
using string functions to parse the symbolic-ref data.  This
should be slightly faster than using a regsub.  I think the
code is clearer too.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

diff --git a/git-gui.sh b/git-gui.sh
index 99df2d94804609d4cff3c1e6e586b262752aaf93..516bd972ec111ecb8a323efa43f0473ab503b1fb 100755 (executable)
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -285,14 +285,24 @@ proc git {args} {
 }
 
 proc current-branch {} {
-       set ref {}
        set fd [open [gitdir HEAD] r]
-       if {[gets $fd ref] <16
-        || ![regsub {^ref: refs/heads/} $ref {} ref]} {
+       if {[gets $fd ref] < 1} {
                set ref {}
        }
        close $fd
-       return $ref
+
+       set pfx {ref: refs/heads/}
+       set len [string length $pfx]
+       if {[string equal -length $len $pfx $ref]} {
+               # We're on a branch.  It might not exist.  But
+               # HEAD looks good enough to be a branch.
+               #
+               return [string range $ref $len end]
+       } else {
+               # Assume this is a detached head.
+               #
+               return HEAD
+       }
 }
 
 auto_load tk_optionMenu