| author |  Ian Johnson <ian@ianjohnson.dev> 2023-08-17 07:52:46-04:00 |
| committer |  GitHub <noreply@github.com> 2023-08-17 07:52:46-04:00 |
| log | f3f554b9b89cc39cf00b4df68bd3455e8ef34984 |
| tree | 819fed8d1bd38c4d6ce10dbdf1cc3def7aec5636 |
| parent | 5395c2786a2ea9fd70e8c91aab099976216089aa |
| signature |  Signed by PGP key 4AEE18F83AFDEB23 |
std.json: avoid stale pointers when parsing Value (#16864)
Closes #16861
Using `alloc_if_needed` when parsing a `Value` allows receiving a token
which points to the buffer of the underlying `Reader`. This token will
no longer be valid after the `Reader`'s buffer is refilled, which will
happen with large values. Using `alloc_always` avoids this issue by
ensuring the returned tokens always own their data independently of the
underlying buffer.2 files changed, 47 insertions(+), 7 deletions(-)
lib- std
lib/std/json/dynamic.zig+7-7
| ... | ... | @@ -93,11 +93,11 @@ pub const Value = union(enum) { |
| 93 | 93 | stack.items[stack.items.len - 1] == .array or |
| 94 | 94 | (stack.items[stack.items.len - 2] == .object and stack.items[stack.items.len - 1] == .string)); |
| 95 | 95 | |
| 96 | switch (try source.nextAlloc(allocator, .alloc_if_needed)) { | |
| 97 | inline .string, .allocated_string => |s| { | |
| 96 | switch (try source.nextAlloc(allocator, .alloc_always)) { | |
| 97 | .allocated_string => |s| { | |
| 98 | 98 | return try handleCompleteValue(&stack, allocator, source, Value{ .string = s }) orelse continue; |
| 99 | 99 | }, |
| 100 | inline .number, .allocated_number => |slice| { | |
| 100 | .allocated_number => |slice| { | |
| 101 | 101 | return try handleCompleteValue(&stack, allocator, source, Value.parseFromNumberSlice(slice)) orelse continue; |
| 102 | 102 | }, |
| 103 | 103 | |
| ... | ... | @@ -106,9 +106,9 @@ pub const Value = union(enum) { |
| 106 | 106 | .false => return try handleCompleteValue(&stack, allocator, source, Value{ .bool = false }) orelse continue, |
| 107 | 107 | |
| 108 | 108 | .object_begin => { |
| 109 | switch (try source.nextAlloc(allocator, .alloc_if_needed)) { | |
| 109 | switch (try source.nextAlloc(allocator, .alloc_always)) { | |
| 110 | 110 | .object_end => return try handleCompleteValue(&stack, allocator, source, Value{ .object = ObjectMap.init(allocator) }) orelse continue, |
| 111 | inline .string, .allocated_string => |key| { | |
| 111 | .allocated_string => |key| { | |
| 112 | 112 | try stack.appendSlice(&[_]Value{ |
| 113 | 113 | Value{ .object = ObjectMap.init(allocator) }, |
| 114 | 114 | Value{ .string = key }, |
| ... | ... | @@ -152,7 +152,7 @@ fn handleCompleteValue(stack: *Array, allocator: Allocator, source: anytype, val |
| 152 | 152 | |
| 153 | 153 | // This is an invalid state to leave the stack in, |
| 154 | 154 | // so we have to process the next token before we return. |
| 155 | switch (try source.nextAlloc(allocator, .alloc_if_needed)) { | |
| 155 | switch (try source.nextAlloc(allocator, .alloc_always)) { | |
| 156 | 156 | .object_end => { |
| 157 | 157 | // This object is complete. |
| 158 | 158 | value = stack.pop(); |
| ... | ... | @@ -160,7 +160,7 @@ fn handleCompleteValue(stack: *Array, allocator: Allocator, source: anytype, val |
| 160 | 160 | if (stack.items.len == 0) return value; |
| 161 | 161 | continue; |
| 162 | 162 | }, |
| 163 | inline .string, .allocated_string => |next_key| { | |
| 163 | .allocated_string => |next_key| { | |
| 164 | 164 | // We've got another key. |
| 165 | 165 | try stack.append(Value{ .string = next_key }); |
| 166 | 166 | // stack: [..., .object, .string] |
lib/std/json/dynamic_test.zig+40
| ... | ... | @@ -15,6 +15,7 @@ const parseFromValueLeaky = @import("static.zig").parseFromValueLeaky; |
| 15 | 15 | const ParseOptions = @import("static.zig").ParseOptions; |
| 16 | 16 | |
| 17 | 17 | const jsonReader = @import("scanner.zig").reader; |
| 18 | const JsonReader = @import("scanner.zig").Reader; | |
| 18 | 19 | |
| 19 | 20 | test "json.parser.dynamic" { |
| 20 | 21 | const s = |
| ... | ... | @@ -288,3 +289,42 @@ test "polymorphic parsing" { |
| 288 | 289 | try testing.expect(tree.div.color == .blue); |
| 289 | 290 | try testing.expectEqualStrings("Cancel", tree.div.children[1].button.caption); |
| 290 | 291 | } |
| 292 | ||
| 293 | test "long object value" { | |
| 294 | const value = "01234567890123456789"; | |
| 295 | const doc = "{\"key\":\"" ++ value ++ "\"}"; | |
| 296 | var fbs = std.io.fixedBufferStream(doc); | |
| 297 | var reader = smallBufferJsonReader(testing.allocator, fbs.reader()); | |
| 298 | defer reader.deinit(); | |
| 299 | var parsed = try parseFromTokenSource(Value, testing.allocator, &reader, .{}); | |
| 300 | defer parsed.deinit(); | |
| 301 | ||
| 302 | try testing.expectEqualStrings(value, parsed.value.object.get("key").?.string); | |
| 303 | } | |
| 304 | ||
| 305 | test "many object keys" { | |
| 306 | const doc = | |
| 307 | \\{ | |
| 308 | \\ "k1": "v1", | |
| 309 | \\ "k2": "v2", | |
| 310 | \\ "k3": "v3", | |
| 311 | \\ "k4": "v4", | |
| 312 | \\ "k5": "v5" | |
| 313 | \\} | |
| 314 | ; | |
| 315 | var fbs = std.io.fixedBufferStream(doc); | |
| 316 | var reader = smallBufferJsonReader(testing.allocator, fbs.reader()); | |
| 317 | defer reader.deinit(); | |
| 318 | var parsed = try parseFromTokenSource(Value, testing.allocator, &reader, .{}); | |
| 319 | defer parsed.deinit(); | |
| 320 | ||
| 321 | try testing.expectEqualStrings("v1", parsed.value.object.get("k1").?.string); | |
| 322 | try testing.expectEqualStrings("v2", parsed.value.object.get("k2").?.string); | |
| 323 | try testing.expectEqualStrings("v3", parsed.value.object.get("k3").?.string); | |
| 324 | try testing.expectEqualStrings("v4", parsed.value.object.get("k4").?.string); | |
| 325 | try testing.expectEqualStrings("v5", parsed.value.object.get("k5").?.string); | |
| 326 | } | |
| 327 | ||
| 328 | fn smallBufferJsonReader(allocator: Allocator, io_reader: anytype) JsonReader(16, @TypeOf(io_reader)) { | |
| 329 | return JsonReader(16, @TypeOf(io_reader)).init(allocator, io_reader); | |
| 330 | } |