1 files changed, 47 insertions, 12 deletions

diff --git a/src/snapshot.c b/src/snapshot.c
index 29ed98c..6578c9a 100644
--- a/src/snapshot.c
+++ b/src/snapshot.c
@@ -73,6 +73,20 @@ static bool reserve(struct term_snapshot *s, int cols, int rows)
     return true;
 }
 
+/* The public contract makes every failed update an empty, retryable snapshot. */
+static void invalidate(struct term_snapshot *s)
+{
+    s->view = (struct term_view){ .palette = s->palette };
+    s->source = 0;
+    s->arena_len = 0;
+    s->arena_dead = 0;
+    if (s->row_cap > 0) {
+        memset(s->keys, 0, (size_t)s->row_cap * sizeof(*s->keys));
+        memset(s->row_clusters, 0, (size_t)s->row_cap * sizeof(*s->row_clusters));
+        memset(s->selection, 0, (size_t)s->row_cap * sizeof(*s->selection));
+    }
+}
+
 /* Attribute contributions of the low and high byte of cell flags. */
 static uint16_t lo_attrs[256], hi_attrs[256];
 static uint8_t hi_underline[256];
@@ -100,7 +114,8 @@ void term_snapshot_tables_init(void)
     }
 }
 
-static uint32_t arena_add(struct term_snapshot *s, const struct gstore *g, uint32_t handle)
+static uint32_t arena_add(struct term_snapshot *s, const struct gstore *g, uint32_t handle,
+                          bool *ok)
 {
     uint32_t cps[GRAPHEME_MAX_LEN];
     int n = term_gstore_expand(g, handle, cps, GRAPHEME_MAX_LEN);
@@ -110,8 +125,10 @@ static uint32_t arena_add(struct term_snapshot *s, const struct gstore *g, uint3
         uint32_t cap = term_grow_cap32(s->arena_cap ? s->arena_cap * 2 : 256,
                                        s->arena_len + (uint32_t)n + 1);
         uint32_t *a = realloc(s->arena, cap * sizeof(*a));
-        if (!a)
-            return cps[0];
+        if (!a) {
+            *ok = false;
+            return 0;
+        }
         s->arena = a;
         s->arena_cap = cap;
     }
@@ -125,7 +142,7 @@ static uint32_t arena_add(struct term_snapshot *s, const struct gstore *g, uint3
 /* Convert one stored row; returns the number of arena words it added. */
 static uint32_t convert_row(struct term_snapshot *s, const struct gstore *g,
                             struct term_cell *dst,
-                            const struct cell *src, int cols)
+                            const struct cell *src, int cols, bool *ok)
 {
     uint32_t before = s->arena_len;
     for (int x = 0; x < cols; x++) {
@@ -138,8 +155,11 @@ static uint32_t convert_row(struct term_snapshot *s, const struct gstore *g,
         uint32_t text = c->c;
         if (TERM_EXPECT(text < 0x20, 0))
             text = text ? ' ' : 0;
-        else if (TERM_EXPECT(grapheme_is_handle(text), 0))
-            text = arena_add(s, g, text);
+        else if (TERM_EXPECT(grapheme_is_handle(text), 0)) {
+            text = arena_add(s, g, text, ok);
+            if (!*ok)
+                return 0;
+        }
         dst[x] = (struct term_cell){
             .text = text,
             .fg = c->fg,
@@ -158,8 +178,7 @@ static bool term_snapshot_update_inner(struct term_snapshot *s, struct term *t)
         return false;
     int cols = t->cols, rows = t->rows;
     if (!reserve(s, cols, rows)) {
-        s->view.size = (struct term_vector2i){ 0 };
-        s->source = 0;
+        invalidate(s);
         return false;
     }
 
@@ -175,13 +194,17 @@ static bool term_snapshot_update_inner(struct term_snapshot *s, struct term *t)
 
     bool changed = all;
     term_hist_prepare_rows(&t->hist, cols);
-    if (!term_hist_view_sync(&t->view, &t->hist, cols))
+    if (!term_hist_view_sync(&t->view, &t->hist, cols)) {
+        invalidate(s);
         return false;
+    }
     term_hist_view_refine(&t->view, &t->hist, cols, rows);
     uint64_t stack_keys[256];
     uint64_t *new_keys = rows <= 256 ? stack_keys : malloc((size_t)rows * sizeof(uint64_t));
-    if (!new_keys)
+    if (!new_keys) {
+        invalidate(s);
         return false;
+    }
     for (int y = 0; y < rows; y++)
         new_keys[y] = term_screen_view_row_key(t, y);
 
@@ -230,6 +253,8 @@ static bool term_snapshot_update_inner(struct term_snapshot *s, struct term *t)
 
     if (scrolled > 0) {
         int k = scrolled;
+        for (int y = 0; y < k; y++)
+            s->arena_dead += s->row_clusters[y];
         memmove(s->cells, s->cells + (size_t)k * cols,
                 (size_t)(rows - k) * cols * sizeof(struct term_cell));
         memmove(s->row_clusters, s->row_clusters + k,
@@ -247,7 +272,15 @@ static bool term_snapshot_update_inner(struct term_snapshot *s, struct term *t)
         if (!all)
             s->arena_dead += s->row_clusters[y];
         const struct cell *src = term_screen_view_row(t, y);
-        s->row_clusters[y] = convert_row(s, t->gstore, s->cells + (size_t)y * cols, src, cols);
+        bool converted = true;
+        s->row_clusters[y] = convert_row(s, t->gstore, s->cells + (size_t)y * cols,
+                                         src, cols, &converted);
+        if (!converted) {
+            if (new_keys != stack_keys)
+                free(new_keys);
+            invalidate(s);
+            return false;
+        }
         s->keys[y] = key;
         changed = true;
     }
@@ -256,8 +289,10 @@ static bool term_snapshot_update_inner(struct term_snapshot *s, struct term *t)
 
     int stack[2][256];
     int *c0 = rows <= 256 ? stack[0] : malloc((size_t)rows * 2 * sizeof(int));
-    if (!c0)
+    if (!c0) {
+        invalidate(s);
         return false;
+    }
     int *c1 = rows <= 256 ? stack[1] : c0 + rows;
     term_selection_view_spans(t, c0, c1);
     for (int y = 0; y < rows; y++) {