forked from
zat.dev/zat
atproto utils for zig
add errdefer for decodeMstNode entries, verify with checkAllAllocationFailures
Add errdefer allocator.free(entries) in decodeMstNode so the entries
slice is freed if a subsequent readMstEntry call fails. Verified with
checkAllAllocationFailures using a hand-built MST node CBOR fixture.
Other MST functions (put, delete, merge, etc.) mutate persistent tree
state and are designed for arena allocators — they can't be verified
with checkAllAllocationFailures due to cumulative allocation patterns.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
+47
+1
src/internal/repo/mst.zig
+1
src/internal/repo/mst.zig
···
858
858
const arr_hdr = cbor.readArrayHeader(data, pos) catch return error.InvalidMstNode;
859
859
pos = arr_hdr.end;
860
860
const entries = try allocator.alloc(MstEntryData, @intCast(arr_hdr.val));
861
+
errdefer allocator.free(entries);
861
862
for (entries) |*entry| {
862
863
const result = readMstEntry(data, pos) catch return error.InvalidMstNode;
863
864
entry.* = result.entry;
+46
src/internal/repo/mst_test.zig
+46
src/internal/repo/mst_test.zig
···
205
205
try std.testing.expectEqual(@as(u32, 1), mst.keyHeight("blue"));
206
206
try std.testing.expectEqual(@as(u32, 0), mst.keyHeight("asdf"));
207
207
}
208
+
209
+
// === allocation failure safety ===
210
+
211
+
fn decodeMstNodeImpl(backing: std.mem.Allocator, data: []const u8) !void {
212
+
var arena = std.heap.ArenaAllocator.init(backing);
213
+
defer arena.deinit();
214
+
_ = try mst.decodeMstNode(arena.allocator(), data);
215
+
}
216
+
217
+
test "checkAllAllocationFailures: decodeMstNode" {
218
+
// build a valid MST node CBOR by hand:
219
+
// map(2) { "e": [ map(4){k,p,t,v}, map(4){k,p,t,v} ], "l": null }
220
+
var setup_arena = std.heap.ArenaAllocator.init(std.testing.allocator);
221
+
defer setup_arena.deinit();
222
+
const sa = setup_arena.allocator();
223
+
224
+
const val_cid = try Cid.forDagCbor(sa, "value");
225
+
226
+
// build entry maps (the "k","p","t","v" maps inside the "e" array)
227
+
const entry1: cbor.Value = .{ .map = &.{
228
+
.{ .key = "k", .value = .{ .bytes = "app.bsky.feed.post/aaa" } },
229
+
.{ .key = "p", .value = .{ .unsigned = 0 } },
230
+
.{ .key = "t", .value = .null },
231
+
.{ .key = "v", .value = .{ .cid = val_cid } },
232
+
} };
233
+
const entry2: cbor.Value = .{
234
+
.map = &.{
235
+
.{ .key = "k", .value = .{ .bytes = "bbb" } },
236
+
.{ .key = "p", .value = .{ .unsigned = 22 } }, // prefix_len = shared with prev key
237
+
.{ .key = "t", .value = .null },
238
+
.{ .key = "v", .value = .{ .cid = val_cid } },
239
+
},
240
+
};
241
+
242
+
const node: cbor.Value = .{ .map = &.{
243
+
.{ .key = "e", .value = .{ .array = &.{ entry1, entry2 } } },
244
+
.{ .key = "l", .value = .null },
245
+
} };
246
+
const encoded = try cbor.encodeAlloc(sa, node);
247
+
248
+
try std.testing.checkAllAllocationFailures(
249
+
std.testing.allocator,
250
+
decodeMstNodeImpl,
251
+
.{encoded},
252
+
);
253
+
}