GODRIVER-3707: Consolidate duplicate binary utility functions from bsoncore and wiremessage packages

internal/binaryutil/binaryutil.go

@@ -0,0 +1,135 @@
+// Copyright (C) MongoDB, Inc. 2025-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+// Package binaryutil provides utility functions for working with binary data.
+package binaryutil
+
+import (
+	"bytes"
+	"encoding/binary"
+)
+
+// Append32 appends a uint32 or int32 value to dst in little-endian byte order.
+// Byte shifting is done directly to prevent overflow security errors, in
+// compliance with gosec G115.
+//
+// See: https://cs.opensource.google/go/go/+/refs/tags/go1.19:src/encoding/binary/binary.go;l=92
+func Append32[T ~uint32 | ~int32](dst []byte, v T) []byte {
+	return append(dst,
+		byte(v),
+		byte(v>>8),
+		byte(v>>16),
+		byte(v>>24),
+	)
+}
+
+// Append64 appends a uint64 or int64 value to dst in little-endian byte order.
+// Byte shifting is done directly to prevent overflow security errors, in
+// compliance with gosec G115.
+//
+// See: https://cs.opensource.google/go/go/+/refs/tags/go1.19:src/encoding/binary/binary.go;l=119
+func Append64[T ~uint64 | ~int64](dst []byte, v T) []byte {
+	return append(dst,
+		byte(v),
+		byte(v>>8),
+		byte(v>>16),
+		byte(v>>24),
+		byte(v>>32),
+		byte(v>>40),
+		byte(v>>48),
+		byte(v>>56),
+	)
+}
+
+// ReadU32 reads a uint32 from src in little-endian byte order. ReadU32 and
+// ReadI32 are separate functions to avoid unsafe casting between unsigned and
+// signed integers.
+func ReadU32(src []byte) (uint32, []byte, bool) {
+	if len(src) < 4 {
+		return 0, src, false
+	}
+
+	return binary.LittleEndian.Uint32(src), src[4:], true
+}
+
+// ReadI32 reads an int32 from src in little-endian byte order.
+// Byte shifting is done directly to prevent overflow security errors, in
+// compliance with gosec G115. ReadU32 and ReadI32 are separate functions to
+// avoid unsafe casting between unsigned and signed integers.
+//
+// See: https://cs.opensource.google/go/go/+/refs/tags/go1.19:src/encoding/binary/binary.go;l=79
+func ReadI32(src []byte) (int32, []byte, bool) {
+	if len(src) < 4 {
+		return 0, src, false
+	}
+
+	_ = src[3] // bounds check hint to compiler
+
+	value := int32(src[0]) |
+		int32(src[1])<<8 |
+		int32(src[2])<<16 |
+		int32(src[3])<<24
+
+	return value, src[4:], true
+}
+
+// ReadU64 reads a uint64 from src in little-endian byte order. ReadU64 and
+// ReadI64 are separate functions to avoid unsafe casting between unsigned and
+// signed integers.
+func ReadU64(src []byte) (uint64, []byte, bool) {
+	if len(src) < 8 {
+		return 0, src, false
+	}
+
+	return binary.LittleEndian.Uint64(src), src[8:], true
+}
+
+// ReadI64 reads an int64 from src in little-endian byte order.
+// Byte shifting is done directly to prevent overflow security errors, in
+// compliance with gosec G115. ReadU64 and ReadI64 are separate functions to
+// avoid unsafe casting between unsigned and signed integers.
+//
+// See: https://cs.opensource.google/go/go/+/refs/tags/go1.19:src/encoding/binary/binary.go;l=101
+func ReadI64(src []byte) (int64, []byte, bool) {
+	if len(src) < 8 {
+		return 0, src, false
+	}
+
+	_ = src[7] // bounds check hint to compiler
+
+	value := int64(src[0]) |
+		int64(src[1])<<8 |
+		int64(src[2])<<16 |
+		int64(src[3])<<24 |
+		int64(src[4])<<32 |
+		int64(src[5])<<40 |
+		int64(src[6])<<48 |
+		int64(src[7])<<56
+
+	return value, src[8:], true
+}
+
+// ReadCStringBytes reads a null-terminated C string from src as a byte slice.
+// This is the base implementation used by ReadCString to ensure a single source
+// of truth for C string parsing logic.
+func ReadCStringBytes(src []byte) ([]byte, []byte, bool) {
+	idx := bytes.IndexByte(src, 0x00)
+	if idx < 0 {
+		return nil, src, false
+	}
+	return src[:idx], src[idx+1:], true
+}
+
+// ReadCString reads a null-terminated C string from src as a string.
+// It delegates to ReadCStringBytes to maintain a single source of truth for
+// C string parsing logic.
+func ReadCString(src []byte) (string, []byte, bool) {
+	cstr, rem, ok := ReadCStringBytes(src)
+	if !ok {
+		return "", src, false
+	}
+	return string(cstr), rem, true
+}