Document correctness findings and save reproduction probe

1 files changed, 80 insertions, 0 deletions

diff --git a/tests/correctness_probe.c b/tests/correctness_probe.c
new file mode 100644
index 0000000..0b55211
--- /dev/null
+++ b/tests/correctness_probe.c
@@ -0,0 +1,80 @@
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+/* Include the implementation to inspect snapshot arena accounting. Link
+ * against the static library so snapshot.c is compiled only here. */
+#include "../src/snapshot.c"
+
+static int fail_realloc;
+static int fail_resize_calloc;
+void *__real_realloc(void *, size_t);
+void *__real_calloc(size_t, size_t);
+void *__wrap_calloc(size_t n, size_t size)
+{
+    if (fail_resize_calloc && n == 2 && size == sizeof(struct srow)) {
+        fail_resize_calloc = 0;
+        return NULL;
+    }
+    return __real_calloc(n, size);
+}
+void *__wrap_realloc(void *ptr, size_t size)
+{
+    if (fail_realloc) { fail_realloc = 0; return NULL; }
+    return __real_realloc(ptr, size);
+}
+
+int main(void)
+{
+    struct term_options options = { .size = { 8, 3 }, .scrollback = 5 };
+    struct term *t = term_new(&options);
+    struct term_snapshot *s = term_snapshot_new();
+    assert(t && s && term_snapshot_update(s, t));
+    const char accented[] = "e\xcc\x81";
+    term_feed(t, accented, sizeof(accented) - 1, 0);
+    fail_realloc = 1;
+    bool ok = term_snapshot_update(s, t);
+    uint32_t cps[16];
+    int n = term_snapshot_cluster(s, term_snapshot_row(s, 0)[0].text, cps, 16);
+    printf("snapshot arena allocation failure: update=%d cluster_length=%d (expected false, or length 2)\n", ok, n);
+    assert(term_snapshot_update(s, t));
+    n = term_snapshot_cluster(s, term_snapshot_row(s, 0)[0].text, cps, 16);
+    printf("retry after allocation recovers: cluster_length=%d (expected 2)\n", n);
+    term_snapshot_free(s);
+    term_free(t);
+
+    options.size.y = 24;
+    t = term_new(&options);
+    s = term_snapshot_new();
+    assert(t && s);
+    const char line[] = "e\xcc\x81\r\n";
+    for (int i = 1; i <= 10000; i++) {
+        term_feed(t, line, sizeof(line) - 1, 0);
+        assert(term_snapshot_update(s, t));
+        if (i == 1000 || i == 10000)
+            printf("after %d lines: arena_words=%u dead_words=%u history_rows=%d\n",
+                   i, s->arena_len, s->arena_dead, term_history_rows(t));
+    }
+    term_snapshot_free(s);
+    term_free(t);
+
+    options.size = (struct term_vector2i){ 8, 4 };
+    t = term_new(&options);
+    s = term_snapshot_new();
+    assert(t && s);
+    const char rows[] = "A\r\nB\r\nC\r\nD";
+    term_feed(t, rows, sizeof(rows) - 1, 0);
+    assert(term_snapshot_update(s, t));
+    printf("before failed height shrink: top=%c cursor_y=%d history=%d\n",
+           (char)term_snapshot_row(s, 0)[0].text, term_cursor(t).pos.y, term_history_rows(t));
+    fail_resize_calloc = 1;
+    ok = term_resize(t, (struct term_vector2i){ 8, 2 });
+    assert(!fail_resize_calloc);
+    assert(term_snapshot_update(s, t));
+    printf("after failed height shrink: resize=%d height=%d top=%c cursor_y=%d history=%d\n",
+           ok, term_size(t).y, (char)term_snapshot_row(s, 0)[0].text,
+           term_cursor(t).pos.y, term_history_rows(t));
+    term_snapshot_free(s);
+    term_free(t);
+    return 0;
+}