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-rw-r--r--lib/std/debug/leb128.zig256
1 files changed, 256 insertions, 0 deletions
diff --git a/lib/std/debug/leb128.zig b/lib/std/debug/leb128.zig
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index 0000000000..cb59c5b0d2
--- /dev/null
+++ b/lib/std/debug/leb128.zig
@@ -0,0 +1,256 @@
+const std = @import("std");
+const testing = std.testing;
+
+pub fn readULEB128(comptime T: type, in_stream: var) !T {
+ const ShiftT = @IntType(false, std.math.log2(T.bit_count));
+
+ var result: T = 0;
+ var shift: usize = 0;
+
+ while (true) {
+ const byte = try in_stream.readByte();
+
+ if (shift > T.bit_count)
+ return error.Overflow;
+
+ var operand: T = undefined;
+ if (@shlWithOverflow(T, byte & 0x7f, @intCast(ShiftT, shift), &operand))
+ return error.Overflow;
+
+ result |= operand;
+
+ if ((byte & 0x80) == 0)
+ return result;
+
+ shift += 7;
+ }
+}
+
+pub fn readULEB128Mem(comptime T: type, ptr: *[*]const u8) !T {
+ const ShiftT = @IntType(false, std.math.log2(T.bit_count));
+
+ var result: T = 0;
+ var shift: usize = 0;
+ var i: usize = 0;
+
+ while (true) : (i += 1) {
+ const byte = ptr.*[i];
+
+ if (shift > T.bit_count)
+ return error.Overflow;
+
+ var operand: T = undefined;
+ if (@shlWithOverflow(T, byte & 0x7f, @intCast(ShiftT, shift), &operand))
+ return error.Overflow;
+
+ result |= operand;
+
+ if ((byte & 0x80) == 0) {
+ ptr.* += i + 1;
+ return result;
+ }
+
+ shift += 7;
+ }
+}
+
+pub fn readILEB128(comptime T: type, in_stream: var) !T {
+ const UT = @IntType(false, T.bit_count);
+ const ShiftT = @IntType(false, std.math.log2(T.bit_count));
+
+ var result: UT = 0;
+ var shift: usize = 0;
+
+ while (true) {
+ const byte = u8(try in_stream.readByte());
+
+ if (shift > T.bit_count)
+ return error.Overflow;
+
+ var operand: UT = undefined;
+ if (@shlWithOverflow(UT, UT(byte & 0x7f), @intCast(ShiftT, shift), &operand)) {
+ if (byte != 0x7f)
+ return error.Overflow;
+ }
+
+ result |= operand;
+
+ shift += 7;
+
+ if ((byte & 0x80) == 0) {
+ if (shift < T.bit_count and (byte & 0x40) != 0) {
+ result |= @bitCast(UT, @intCast(T, -1)) << @intCast(ShiftT, shift);
+ }
+ return @bitCast(T, result);
+ }
+ }
+}
+
+pub fn readILEB128Mem(comptime T: type, ptr: *[*]const u8) !T {
+ const UT = @IntType(false, T.bit_count);
+ const ShiftT = @IntType(false, std.math.log2(T.bit_count));
+
+ var result: UT = 0;
+ var shift: usize = 0;
+ var i: usize = 0;
+
+ while (true) : (i += 1) {
+ const byte = ptr.*[i];
+
+ if (shift > T.bit_count)
+ return error.Overflow;
+
+ var operand: UT = undefined;
+ if (@shlWithOverflow(UT, UT(byte & 0x7f), @intCast(ShiftT, shift), &operand)) {
+ if (byte != 0x7f)
+ return error.Overflow;
+ }
+
+ result |= operand;
+
+ shift += 7;
+
+ if ((byte & 0x80) == 0) {
+ if (shift < T.bit_count and (byte & 0x40) != 0) {
+ result |= @bitCast(UT, @intCast(T, -1)) << @intCast(ShiftT, shift);
+ }
+ ptr.* += i + 1;
+ return @bitCast(T, result);
+ }
+ }
+}
+
+fn test_read_stream_ileb128(comptime T: type, encoded: []const u8) !T {
+ var in_stream = std.io.SliceInStream.init(encoded);
+ return try readILEB128(T, &in_stream.stream);
+}
+
+fn test_read_stream_uleb128(comptime T: type, encoded: []const u8) !T {
+ var in_stream = std.io.SliceInStream.init(encoded);
+ return try readULEB128(T, &in_stream.stream);
+}
+
+fn test_read_ileb128(comptime T: type, encoded: []const u8) !T {
+ var in_stream = std.io.SliceInStream.init(encoded);
+ const v1 = readILEB128(T, &in_stream.stream);
+ var in_ptr = encoded.ptr;
+ const v2 = readILEB128Mem(T, &in_ptr);
+ testing.expectEqual(v1, v2);
+ return v1;
+}
+
+fn test_read_uleb128(comptime T: type, encoded: []const u8) !T {
+ var in_stream = std.io.SliceInStream.init(encoded);
+ const v1 = readULEB128(T, &in_stream.stream);
+ var in_ptr = encoded.ptr;
+ const v2 = readULEB128Mem(T, &in_ptr);
+ testing.expectEqual(v1, v2);
+ 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"));
+
+ // Overflow
+ testing.expectError(error.Overflow, test_read_ileb128(i8, "\x80\x80\x40"));
+ testing.expectError(error.Overflow, test_read_ileb128(i16, "\x80\x80\x80\x40"));
+ testing.expectError(error.Overflow, test_read_ileb128(i32, "\x80\x80\x80\x80\x40"));
+ testing.expectError(error.Overflow, test_read_ileb128(i64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x40"));
+ testing.expectError(error.Overflow, test_read_ileb128(i8, "\xff\x7e"));
+
+ // Decode SLEB128
+ testing.expect((try test_read_ileb128(i64, "\x00")) == 0);
+ testing.expect((try test_read_ileb128(i64, "\x01")) == 1);
+ testing.expect((try test_read_ileb128(i64, "\x3f")) == 63);
+ testing.expect((try test_read_ileb128(i64, "\x40")) == -64);
+ testing.expect((try test_read_ileb128(i64, "\x41")) == -63);
+ testing.expect((try test_read_ileb128(i64, "\x7f")) == -1);
+ testing.expect((try test_read_ileb128(i64, "\x80\x01")) == 128);
+ testing.expect((try test_read_ileb128(i64, "\x81\x01")) == 129);
+ testing.expect((try test_read_ileb128(i64, "\xff\x7e")) == -129);
+ testing.expect((try test_read_ileb128(i64, "\x80\x7f")) == -128);
+ testing.expect((try test_read_ileb128(i64, "\x81\x7f")) == -127);
+ testing.expect((try test_read_ileb128(i64, "\xc0\x00")) == 64);
+ testing.expect((try test_read_ileb128(i64, "\xc7\x9f\x7f")) == -12345);
+ testing.expect((try test_read_ileb128(i8, "\xff\x7f")) == -1);
+ testing.expect((try test_read_ileb128(i16, "\xff\xff\x7f")) == -1);
+ testing.expect((try test_read_ileb128(i32, "\xff\xff\xff\xff\x7f")) == -1);
+ testing.expect((try test_read_ileb128(i32, "\x80\x80\x80\x80\x08")) == -0x80000000);
+ testing.expect((try test_read_ileb128(i64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x01")) == @bitCast(i64, @intCast(u64, 0x8000000000000000)));
+ testing.expect((try test_read_ileb128(i64, "\x80\x80\x80\x80\x80\x80\x80\x80\x40")) == -0x4000000000000000);
+ testing.expect((try test_read_ileb128(i64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x7f")) == -0x8000000000000000);
+
+ // Decode unnormalized SLEB128 with extra padding bytes.
+ testing.expect((try test_read_ileb128(i64, "\x80\x00")) == 0);
+ testing.expect((try test_read_ileb128(i64, "\x80\x80\x00")) == 0);
+ testing.expect((try test_read_ileb128(i64, "\xff\x00")) == 0x7f);
+ 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" {
+ // Truncated
+ testing.expectError(error.EndOfStream, test_read_stream_uleb128(u64, "\x80"));
+
+ // Overflow
+ testing.expectError(error.Overflow, test_read_uleb128(u8, "\x80\x02"));
+ testing.expectError(error.Overflow, test_read_uleb128(u8, "\x80\x80\x40"));
+ testing.expectError(error.Overflow, test_read_uleb128(u16, "\x80\x80\x84"));
+ testing.expectError(error.Overflow, test_read_uleb128(u16, "\x80\x80\x80\x40"));
+ testing.expectError(error.Overflow, test_read_uleb128(u32, "\x80\x80\x80\x80\x90"));
+ testing.expectError(error.Overflow, test_read_uleb128(u32, "\x80\x80\x80\x80\x40"));
+ testing.expectError(error.Overflow, test_read_uleb128(u64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x40"));
+
+ // Decode ULEB128
+ testing.expect((try test_read_uleb128(u64, "\x00")) == 0);
+ testing.expect((try test_read_uleb128(u64, "\x01")) == 1);
+ testing.expect((try test_read_uleb128(u64, "\x3f")) == 63);
+ testing.expect((try test_read_uleb128(u64, "\x40")) == 64);
+ testing.expect((try test_read_uleb128(u64, "\x7f")) == 0x7f);
+ testing.expect((try test_read_uleb128(u64, "\x80\x01")) == 0x80);
+ testing.expect((try test_read_uleb128(u64, "\x81\x01")) == 0x81);
+ testing.expect((try test_read_uleb128(u64, "\x90\x01")) == 0x90);
+ testing.expect((try test_read_uleb128(u64, "\xff\x01")) == 0xff);
+ testing.expect((try test_read_uleb128(u64, "\x80\x02")) == 0x100);
+ testing.expect((try test_read_uleb128(u64, "\x81\x02")) == 0x101);
+ testing.expect((try test_read_uleb128(u64, "\x80\xc1\x80\x80\x10")) == 4294975616);
+ testing.expect((try test_read_uleb128(u64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x01")) == 0x8000000000000000);
+
+ // Decode ULEB128 with extra padding bytes
+ testing.expect((try test_read_uleb128(u64, "\x80\x00")) == 0);
+ testing.expect((try test_read_uleb128(u64, "\x80\x80\x00")) == 0);
+ testing.expect((try test_read_uleb128(u64, "\xff\x00")) == 0x7f);
+ 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");
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-12-27 19:48:50 +0000