-perm: Handle permcopy (e.g. u=rw,g=u) correctly

3 files changed, 22 insertions, 5 deletions

diff --git a/parse.c b/parse.c
index ed7685b..4a01467 100644
--- a/parse.c
+++ b/parse.c
@@ -1507,21 +1507,32 @@ static int parse_mode(const struct parser_state *state, const char *mode, struct
 			break;
 
 		case MODE_OP:
-			file_change = 0;
-			dir_change = 0;
-
 			switch (*i) {
 			case 'u':
+				file_change = (expr->file_mode >> 6) & 07;
+				dir_change = (expr->dir_mode >> 6) & 07;
+				break;
 			case 'g':
+				file_change = (expr->file_mode >> 3) & 07;
+				dir_change = (expr->dir_mode >> 3) & 07;
+				break;
 			case 'o':
-				// PERMCOPY (e.g. u=g) has no effect for -perm
-				mstate = MODE_ACTION_APPLY;
+				file_change = expr->file_mode & 07;
+				dir_change = expr->dir_mode & 07;
 				break;
 
 			default:
+				file_change = 0;
+				dir_change = 0;
 				mstate = MODE_PERM;
 				continue;
 			}
+
+			file_change |= (file_change << 6) | (file_change << 3);
+			file_change &= who;
+			dir_change |= (dir_change << 6) | (dir_change << 3);
+			dir_change &= who;
+			mstate = MODE_ACTION_APPLY;
 			break;
 
 		case MODE_PERM:
diff --git a/tests.sh b/tests.sh
index c518f33..2fce23b 100755
--- a/tests.sh
+++ b/tests.sh
@@ -164,6 +164,7 @@ posix_tests=(
     test_perm_symbolic
     test_perm_symbolic_minus
     test_perm_leading_plus_symbolic_minus
+    test_permcopy
     test_ok_stdin
     test_parens
     test_bang
@@ -833,6 +834,10 @@ function test_perm_octal_plus() {
     ! $BFS perms -perm +777 2>/dev/null
 }
 
+function test_permcopy() {
+    bfs_diff perms -perm u+rw,g+u-w,o=g
+}
+
 function test_ok_stdin() {
     # -ok should *not* close stdin
     # See https://savannah.gnu.org/bugs/?24561
diff --git a/tests/test_permcopy.out b/tests/test_permcopy.out
new file mode 100644
index 0000000..4e64e49
--- /dev/null
+++ b/tests/test_permcopy.out
@@ -0,0 +1 @@
+perms/rw