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std: by default, disallow trailing data when parsing json

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daurnimator 2021-05-30 17:27:42 +10:00 committed by Veikka Tuominen
parent 556d3e3d80
commit 57cf9f7ea6
1 changed files with 25 additions and 6 deletions
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31
lib/std/json.zig
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@ -1464,6 +1464,8 @@ pub const ParseOptions = struct {
/// If false, finding an unknown field returns an error.
ignore_unknown_fields: bool = false,
allow_trailing_data: bool = false,
};
fn skipValue(tokens: *TokenStream) !void {
@ -1627,6 +1629,8 @@ fn parseInternal(comptime T: type, token: Token, tokens: *TokenStream, options:
.ObjectEnd => break,
.String => |stringToken| {
const key_source_slice = stringToken.slice(tokens.slice, tokens.i - 1);
var child_options = options;
child_options.allow_trailing_data = true;
var found = false;
inline for (structInfo.fields) |field, i| {
// TODO: using switches here segfault the compiler (#2727?)
@ -1643,24 +1647,24 @@ fn parseInternal(comptime T: type, token: Token, tokens: *TokenStream, options:
// }
if (options.duplicate_field_behavior == .UseFirst) {
// unconditonally ignore value. for comptime fields, this skips check against default_value
parseFree(field.field_type, try parse(field.field_type, tokens, options), options);
parseFree(field.field_type, try parse(field.field_type, tokens, child_options), child_options);
found = true;
break;
} else if (options.duplicate_field_behavior == .Error) {
return error.DuplicateJSONField;
} else if (options.duplicate_field_behavior == .UseLast) {
if (!field.is_comptime) {
parseFree(field.field_type, @field(r, field.name), options);
parseFree(field.field_type, @field(r, field.name), child_options);
}
fields_seen[i] = false;
}
}
if (field.is_comptime) {
if (!try parsesTo(field.field_type, field.default_value.?, tokens, options)) {
if (!try parsesTo(field.field_type, field.default_value.?, tokens, child_options)) {
return error.UnexpectedValue;
}
} else {
@field(r, field.name) = try parse(field.field_type, tokens, options);
@field(r, field.name) = try parse(field.field_type, tokens, child_options);
}
fields_seen[i] = true;
found = true;
@ -1697,6 +1701,8 @@ fn parseInternal(comptime T: type, token: Token, tokens: *TokenStream, options:
.ArrayBegin => {
var r: T = undefined;
var i: usize = 0;
var child_options = options;
child_options.allow_trailing_data = true;
errdefer {
// Without the r.len check `r[i]` is not allowed
if (r.len > 0) while (true) : (i -= 1) {
@ -1705,7 +1711,7 @@ fn parseInternal(comptime T: type, token: Token, tokens: *TokenStream, options:
};
}
while (i < r.len) : (i += 1) {
r[i] = try parse(arrayInfo.child, tokens, options);
r[i] = try parse(arrayInfo.child, tokens, child_options);
}
const tok = (try tokens.next()) orelse return error.UnexpectedEndOfJson;
switch (tok) {
@ -1786,7 +1792,13 @@ fn parseInternal(comptime T: type, token: Token, tokens: *TokenStream, options:
pub fn parse(comptime T: type, tokens: *TokenStream, options: ParseOptions) !T {
const token = (try tokens.next()) orelse return error.UnexpectedEndOfJson;
return parseInternal(T, token, tokens, options);
const r = try parseInternal(T, token, tokens, options);
errdefer parseFree(T, r, options);
if (!options.allow_trailing_data) {
if ((try tokens.next()) != null) unreachable;
assert(tokens.i >= tokens.slice.len);
}
return r;
}
/// Releases resources created by `parse`.
@ -1871,6 +1883,13 @@ test "parse into enum" {
try testing.expectError(error.InvalidEnumTag, parse(T, &TokenStream.init("\"Qux\""), ParseOptions{}));
}
test "parse with trailing data" {
try testing.expectEqual(false, try parse(bool, &TokenStream.init("falsed"), ParseOptions{ .allow_trailing_data = true }));
try testing.expectError(error.InvalidTopLevelTrailing, parse(bool, &TokenStream.init("falsed"), ParseOptions{ .allow_trailing_data = false }));
// trailing whitespace is okay
try testing.expectEqual(false, try parse(bool, &TokenStream.init("false \n"), ParseOptions{ .allow_trailing_data = false }));
}
test "parse into that allocates a slice" {
try testing.expectError(error.AllocatorRequired, parse([]u8, &TokenStream.init("\"foo\""), ParseOptions{}));