Add more tests for pagerhist

kitty/history.c

@@ -203,16 +203,24 @@ pagerhist_write_bytes(PagerHistoryBuf *ph, const uint8_t *buf, size_t sz) {
     return true;
 }
 
-static inline void
+static inline bool
 pagerhist_ensure_start_is_valid_utf8(PagerHistoryBuf *ph) {
     uint32_t state = UTF8_ACCEPT, codep;
-    while (ph->length) {
-        decode_utf8(&state, &codep, ph->buffer[ph->start]);
+    size_t pos = ph->start, count = 0;
+    size_t last_reject_at = 0;
+    while (count < ph->length) {
+        decode_utf8(&state, &codep, ph->buffer[pos]);
+        count++;
         if (state == UTF8_ACCEPT) break;
-        if (state == UTF8_REJECT) state = UTF8_ACCEPT;
-        ph->start = ph->start == ph->buffer_size - 1 ? 0 : ph->start + 1;
-        ph->length--;
+        if (state == UTF8_REJECT) { state = UTF8_ACCEPT; last_reject_at = count; }
+        pos = pos == ph->buffer_size - 1 ? 0: pos + 1;
     }
+    if (last_reject_at) {
+        ph->start = (ph->start + last_reject_at) % ph->buffer_size;
+        ph->length -= last_reject_at;
+        return true;
+    }
+    return false;
 }
 
 static inline bool

kitty_tests/screen.py

@@ -477,6 +477,9 @@ class TestScreen(BaseTest):
         def line(i):
             q.append('\x1b[m' + f'{i}' * s.columns + '\r')
 
+        def w(x):
+            s.historybuf.pagerhist_write(x)
+
         def test():
             expected = ''.join(q)
             maxlen = hsz
@@ -497,6 +500,21 @@ class TestScreen(BaseTest):
         s.draw('8' * s.columns), line(4), test()
         s.draw('9' * s.columns), line(5), test()
 
+        s = self.create_screen(options={'scrollback_pager_history_size': 2048})
+        text = '\x1b[msoft\r\x1b[mbreak\nnext😼cat'
+        w(text)
+        self.ae(contents(), text + '\n')
+        s.historybuf.pagerhist_rewrap(2)
+        self.ae(contents(), '\x1b[mso\rft\x1b[m\rbr\rea\rk\nne\rxt\r😼\rca\rt\n')
+
+        s = self.create_screen(options={'scrollback_pager_history_size': 8})
+        w('😼')
+        self.ae(contents(), '😼\n')
+        w('abcd')
+        self.ae(contents(), '😼abcd\n')
+        w('e')
+        self.ae(contents(), 'abcde\n')
+
     def test_user_marking(self):
 
         def cells(*a, y=0, mark=3):