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Fix off-by-one error in LEB128 parsing

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LemonBoy 2019-05-15 09:41:38 +02:00 committed by Andrew Kelley
parent 057a5d4898
commit 787fd0f1be
1 changed files with 30 additions and 2 deletions
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32
std/debug/leb128.zig
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@ -46,7 +46,7 @@ pub fn readULEB128Mem(comptime T: type, ptr: *[*]const u8) !T {
result |= operand;
if ((byte & 0x80) == 0) {
ptr.* += i;
ptr.* += i + 1;
return result;
}
@ -114,7 +114,7 @@ pub fn readILEB128Mem(comptime T: type, ptr: *[*]const u8) !T {
if (shift < T.bit_count and (byte & 0x40) != 0) {
result |= @bitCast(UT, @intCast(T, -1)) << @intCast(ShiftT, shift);
}
ptr.* += i;
ptr.* += i + 1;
return @bitCast(T, result);
}
}
@ -148,6 +148,28 @@ fn test_read_uleb128(comptime T: type, encoded: []const u8) !T {
return v1;
}
fn test_read_ileb128_seq(comptime T: type, comptime N: usize, encoded: []const u8) void {
var in_stream = std.io.SliceInStream.init(encoded);
var in_ptr = encoded.ptr;
var i: usize = 0;
while (i < N) : (i += 1) {
const v1 = readILEB128(T, &in_stream.stream);
const v2 = readILEB128Mem(T, &in_ptr);
testing.expectEqual(v1, v2);
}
}
fn test_read_uleb128_seq(comptime T: type, comptime N: usize, encoded: []const u8) void {
var in_stream = std.io.SliceInStream.init(encoded);
var in_ptr = encoded.ptr;
var i: usize = 0;
while (i < N) : (i += 1) {
const v1 = readULEB128(T, &in_stream.stream);
const v2 = readULEB128Mem(T, &in_ptr);
testing.expectEqual(v1, v2);
}
}
test "deserialize signed LEB128" {
// Truncated
testing.expectError(error.EndOfStream, test_read_stream_ileb128(i64, "\x80"));
@ -188,6 +210,9 @@ test "deserialize signed LEB128" {
testing.expect((try test_read_ileb128(i64, "\xff\x80\x00")) == 0x7f);
testing.expect((try test_read_ileb128(i64, "\x80\x81\x00")) == 0x80);
testing.expect((try test_read_ileb128(i64, "\x80\x81\x80\x00")) == 0x80);
// Decode sequence of SLEB128 values
test_read_ileb128_seq(i64, 4, "\x81\x01\x3f\x80\x7f\x80\x80\x80\x00");
}
test "deserialize unsigned LEB128" {
@ -225,4 +250,7 @@ test "deserialize unsigned LEB128" {
testing.expect((try test_read_uleb128(u64, "\xff\x80\x00")) == 0x7f);
testing.expect((try test_read_uleb128(u64, "\x80\x81\x00")) == 0x80);
testing.expect((try test_read_uleb128(u64, "\x80\x81\x80\x00")) == 0x80);
// Decode sequence of ULEB128 values
test_read_uleb128_seq(u64, 4, "\x81\x01\x3f\x80\x7f\x80\x80\x80\x00");
}