Adjust patch to use dlist_pop()

3 files changed, 11 insertions, 10 deletions

diff --git a/lib/llist.c b/lib/llist.c
index 596da40f..71a187db 100644
--- a/lib/llist.c
+++ b/lib/llist.c
@@ -37,8 +37,11 @@ void *dlist_pop(void *list)
 {
   struct double_list **pdlist = (struct double_list **)list, *dlist = *pdlist;
 
-  dlist->next->prev = dlist->prev;
-  dlist->prev->next = *pdlist = dlist->next;
+  if (dlist->next == dlist) *pdlist = 0;
+  else {
+    dlist->next->prev = dlist->prev;
+    dlist->prev->next = *pdlist = dlist->next;
+  }
 
   return dlist;
 }
diff --git a/scripts/test/test.test b/scripts/test/test.test
index a66dd3c6..f5011573 100755
--- a/scripts/test/test.test
+++ b/scripts/test/test.test
@@ -61,3 +61,7 @@ testing "test -gt" "arith_test -gt" "g\n" "" ""
 testing "test -ge" "arith_test -ge" "e\ng\n" "" ""
 testing "test -lt" "arith_test -lt" "l\n" "" ""
 testing "test -le" "arith_test -le" "l\ne\n" "" ""
+
+# test ! = -o a
+# test ! \( = -o a \)
+# test \( ! = \) -o a
diff --git a/toys/posix/patch.c b/toys/posix/patch.c
index bb443484..7fb6add3 100644
--- a/toys/posix/patch.c
+++ b/toys/posix/patch.c
@@ -204,18 +204,12 @@ static int apply_one_hunk(void)
         if (PATCH_DEBUG) fprintf(stderr, "NOT: %s\n", plist->data);
 
         TT.state = 3;
-        check = llist_pop(&buf);
-        check->prev->next = buf;
-        buf->prev = check->prev;
-        do_line(check);
+        do_line(check = dlist_pop(&buf));
         plist = TT.current_hunk;
 
         // If we've reached the end of the buffer without confirming a
         // match, read more lines.
-        if (check==buf) {
-          buf = 0;
-          break;
-        }
+        if (!buf) break;
         check = buf;
       } else {
         if (PATCH_DEBUG) fprintf(stderr, "MAYBE: %s\n", plist->data);