LibACPI: Add support for strings

Co-authored-by: RatcheT2497 <[email protected]>

Userland/Libraries/LibACPI/Interpreter.cpp

@@ -195,7 +195,7 @@ ErrorOr<Object> Interpreter::finalize_value_opcode(OpcodeFrame& frame)
     case Opcode::WordPrefix:
     case Opcode::DWordPrefix:
     case Opcode::QWordPrefix:
-        VERIFY(frame.operand(0).is<u64>());
+    case Opcode::StringPrefix:
         return frame.operand(0);
 
     default:
@@ -315,6 +315,12 @@ ErrorOr<IterationDecision> Interpreter::read_operand(TableStream& stream, Operan
         TRY(top_opcode_frame.finish_operand(value, stream.offset()));
         return IterationDecision::Continue;
     }
+    case OperandType::String: {
+        DEBUG_LOG("Reading string...");
+        auto value = TRY(stream.read_string());
+        TRY(top_opcode_frame.finish_operand(String(value), stream.offset()));
+        return IterationDecision::Continue;
+    }
 
     // https://uefi.org/specs/ACPI/6.6/20_AML_Specification.html#fieldelement
     case OperandType::FieldElement: {

Userland/Libraries/LibACPI/Object.h

@@ -16,8 +16,21 @@
 
 namespace ACPI::AML {
 
+class String {
+public:
+    String(ByteBuffer buffer)
+        : m_buffer(move(buffer))
+    {
+    }
+
+    ByteBuffer& buffer() { return m_buffer; }
+
+private:
+    ByteBuffer m_buffer;
+};
+
 template<typename T>
-concept IsNodeData = OneOf<T, u64, NameString>;
+concept IsNodeData = OneOf<T, u64, String, NameString>;
 
 class Object {
 public:
@@ -50,7 +63,7 @@ public:
     }
 
 protected:
-    Variant<AK::Empty, u64, NameString> m_data;
+    Variant<AK::Empty, u64, String, NameString> m_data;
 };
 
 }
@@ -64,6 +77,9 @@ struct AK::Formatter<::ACPI::AML::Object> : AK::Formatter<FormatString> {
             return AK::Formatter<FormatString>::format(builder, "(Decimal: {}, Hexadecimal: {:X})"sv, value, value);
         }
 
+        if (object.is<::ACPI::AML::String>())
+            return AK::Formatter<FormatString>::format(builder, "'{}'"sv, StringView(MUST(object.as<::ACPI::AML::String>()).buffer()));
+
         if (object.is<::ACPI::AML::NameString>())
             return AK::Formatter<FormatString>::format(builder, "{}"sv, TRY(MUST(object.as<::ACPI::AML::NameString>()).to_string()));
 

Userland/Libraries/LibACPI/OpcodeFrame.cpp

@@ -25,6 +25,7 @@ constexpr static Array<OperandType, 2> BYTE_CONST_OPERANDS = { OperandType::Byte
 constexpr static Array<OperandType, 2> WORD_CONST_OPERANDS = { OperandType::WordData, OperandType::End };
 constexpr static Array<OperandType, 2> DWORD_CONST_OPERANDS = { OperandType::DWordData, OperandType::End };
 constexpr static Array<OperandType, 2> QWORD_CONST_OPERANDS = { OperandType::QWordData, OperandType::End };
+constexpr static Array<OperandType, 2> STRING_CONST_OPERANDS = { OperandType::String, OperandType::End };
 
 constexpr static Array<OperandType, 4> METHOD_OPERANDS = {
     OperandType::PackageLength,
@@ -68,6 +69,8 @@ static ErrorOr<ReadonlySpan<OperandType>> get_opcode_operand_template(Opcode opc
         return DWORD_CONST_OPERANDS.span();
     case Opcode::QWordPrefix:
         return QWORD_CONST_OPERANDS.span();
+    case Opcode::StringPrefix:
+        return STRING_CONST_OPERANDS.span();
 
     case Opcode::ScopeOp:
         return SCOPE_OPERANDS.span();
@@ -123,6 +126,7 @@ bool OpcodeFrame::filter_opcode_for_next_operand(Opcode opcode)
     case OperandType::WordData:
     case OperandType::DWordData:
     case OperandType::QWordData:
+    case OperandType::String:
     case OperandType::FieldElement:
         return false;
 

Userland/Libraries/LibACPI/OpcodeFrame.h

@@ -20,6 +20,7 @@ enum class OperandType : u8 {
     WordData,
     DWordData,
     QWordData,
+    String,
 
     FieldElement,
     TermArg,

Userland/Libraries/LibACPI/TableStream.cpp

@@ -45,6 +45,33 @@ ErrorOr<u32> TableStream::read_package_length()
     return value;
 }
 
+// https://uefi.org/specs/ACPI/6.6/20_AML_Specification.html#stringprefix
+ErrorOr<ByteBuffer> TableStream::read_string()
+{
+    size_t start = offset();
+
+    u8 b = TRY(read_value<u8>());
+    if (b == 0)
+        return ByteBuffer::create_uninitialized(0);
+
+    do {
+        if (b > 0x7f) {
+            warnln("Invalid character in string: {} at offset {}", b, offset());
+            return Error::from_string_view_or_print_error_and_return_errno("Invalid character in string!"sv, EINVAL);
+        }
+
+        b = TRY(read_value<u8>());
+    } while (b != 0);
+
+    size_t size = offset() - start;
+    TRY(seek(start));
+
+    auto span = TRY(read_in_place<u8 const>(size - 1));
+    // Skip over null byte so it doesn't end up in the buffer.
+    TRY(seek(1, SeekMode::FromCurrentPosition));
+    return ByteBuffer::copy(span);
+}
+
 // https://uefi.org/specs/ACPI/6.6/20_AML_Specification.html#namestring
 ErrorOr<NameString> TableStream::read_name_string()
 {

Userland/Libraries/LibACPI/TableStream.h

@@ -24,6 +24,7 @@ public:
 
     ErrorOr<Opcode> read_opcode();
     ErrorOr<u32> read_package_length();
+    ErrorOr<ByteBuffer> read_string();
     ErrorOr<NameString> read_name_string();
 
     ErrorOr<u8> peek_byte();