git-hooks: don't stage unstaged hunks before commit

We call 'git add' for files where we fixed whitespaces in. This is a
problem in case the user staged only part of a file - as a result we do
not just fix up whitespace in the patch but also stage other hunks of
the file.

Fix the problem by removing/restoring not staged changes before/after
whitespace fixing. The operation is cheap enough, as it's a noop in case
there are no unstaged changes.

1 files changed, 16 insertions, 0 deletions

diff --git a/git-hooks/pre-commit b/git-hooks/pre-commit
index cee3a7f4ac8a..8192e5840c56 100755
--- a/git-hooks/pre-commit
+++ b/git-hooks/pre-commit
@@ -58,6 +58,18 @@ sub check_and_fix_whitespace($)
     my $line_no = 0;
     my $line_max = -1;
 
+    my $stash = "";
+
+    # any not staged changes to stash away?
+    system( "git update-index -q --refresh" );
+    if ( `git diff --name-only --` ) {
+        my $fd;
+        ( $fd, $stash ) = mkstemp( "/tmp/unstaged-changes-XXXXXX" );
+        close( $fd );
+        # this will keep the staged changes
+        system( "git diff > $stash" );
+        system( "git checkout ." );
+    }
     open( IN, "git diff-index -p --no-prefix --cached $head -- |" ) || die "Cannot get git diff-index";
     while ( my $line = <IN> ) {
         if ( $line =~ /^\+\+\+ (.*)/ ) {
@@ -80,6 +92,10 @@ sub check_and_fix_whitespace($)
     }
     fix_whitespace( $file, \%lines );
     close( IN );
+    if ($stash) {
+        system( "git apply < $stash" );
+        unlink( $stash );
+    }
 }
 
 # Do the work :-)