More Bytecode and Attributes support

src/bytecode.rs

@@ -0,0 +1,68 @@
+use core::fmt::Debug;
+use core::fmt;
+
+pub struct Bytecode {
+    pub code: Box<[u8]>
+}
+
+impl Bytecode {
+    pub fn opcodes(&self) -> Box<[Instruction]> {
+        let mut v = Vec::with_capacity(self.code.len());
+        
+        let mut i = 0;
+        while i < self.code.len() {
+            let opcode = self.code[i];
+
+            let (instruction, offset) = match opcode {
+                0x12 => (Instruction::LoadConstant(self.code[i+1]), 2),
+                0x2A => (Instruction::LoadReference0(), 1),
+                0x2B => (Instruction::LoadReference1(), 1),
+                0x2C => (Instruction::LoadReference2(), 1),
+                0x2D => (Instruction::LoadReference3(), 1),
+                0x59 => (Instruction::Duplicate(), 1),
+                0xB0 => (Instruction::ReturnReference(), 1),
+                0xB1 => (Instruction::ReturnVoid(), 1),
+                0xB2 => (Instruction::GetStatic(self.code[i+1], self.code[i+2]), 3),
+                0xB4 => (Instruction::GetField(self.code[i+1], self.code[i+2]), 3),
+                0xB5 => (Instruction::PutField(self.code[i+1], self.code[i+2]), 3),
+                0xB6 => (Instruction::InvokeVirtual(self.code[i+1], self.code[i+2]), 3),
+                0xB7 => (Instruction::InvokeSpecial(self.code[i+1], self.code[i+2]), 3),
+                0xBB => (Instruction::NewObject(self.code[i+1], self.code[i+2]), 3),
+                _ => (Instruction::Unknown(opcode), 1)
+            };
+
+            v.push(instruction);
+            i += offset;
+        }
+
+        v.into_boxed_slice()
+    }
+}
+
+impl Debug for Bytecode {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
+        f.debug_list()
+            .entries(self.opcodes())
+            .finish()
+    }
+}
+
+#[derive(Debug)]
+#[repr(u8)]
+pub enum Instruction {
+    LoadConstant(u8)      = 0x12, // Push from constant pool
+    LoadReference0()      = 0x2A, // Load local variable reference onto stack
+    LoadReference1()      = 0x2B, // Load local variable reference onto stack
+    LoadReference2()      = 0x2C, // Load local variable reference onto stack
+    LoadReference3()      = 0x2D, // Load local variable reference onto stack
+    Duplicate()           = 0x59, // duplicate top stack value
+    ReturnReference()     = 0xB0, // return top-ref from current function
+    ReturnVoid()          = 0xB1, // return void from function
+    GetStatic(u8, u8)     = 0xB2, // get static field from class
+    GetField(u8, u8)      = 0xB4, // get field from class
+    PutField(u8, u8)      = 0xB5, // set field to a value
+    InvokeVirtual(u8, u8) = 0xB6, // invoke function on a class
+    InvokeSpecial(u8, u8) = 0xB7, // invoke instance method
+    NewObject(u8, u8)     = 0xBB, // Create a new object from a constant-pool reference
+    Unknown(u8),
+}

src/classfile.rs

@@ -3,6 +3,7 @@ use std::error::Error as ErrorTrait;
 use core::fmt::{Display, Formatter, Debug};
 use core::str::Utf8Error;
 
+use crate::bytecode::Bytecode;
 
 #[derive(Debug)]
 pub enum Error {
@@ -135,7 +136,7 @@ impl JavaClassFile {
 
             methods_vec.into_boxed_slice()
         };
-        let attributes = AttributeInfo::array_from_reader(reader, &constant_pool)?;
+        let attributes = AttributeInfo::array_from_reader(reader, &constant_pool, true)?;
 
         Ok(
             JavaClassFile {
@@ -472,7 +473,7 @@ impl FieldInfo {
                access_flags: AccessFlagMask { mask: read_u16(reader)? },
                name_index: read_u16(reader)?,
                descriptor_index: read_u16(reader)?,
-               attributes: AttributeInfo::array_from_reader(reader, pool)?,
+               attributes: AttributeInfo::array_from_reader(reader, pool, true)?,
             }
         )
     }
@@ -530,11 +531,178 @@ impl LineNumberTableAttributeData {
     }
 }
 
+#[derive(Debug)] 
+pub struct ExceptionTableEntry {
+    start_pc: u16,
+    end_pc: u16,
+    handler_pc: u16,
+    catch_type: u16,
+}
+
+impl ExceptionTableEntry {
+    fn from_reader(reader: &mut dyn Read) -> Result<Self, Error> {
+        Ok(
+            ExceptionTableEntry {
+                start_pc: read_u16(reader)?,
+                end_pc: read_u16(reader)?,
+                handler_pc: read_u16(reader)?,
+                catch_type: read_u16(reader)?,
+            }
+        )
+    }
+}
+
+#[derive(Debug)] 
+pub struct CodeAttributeData {
+    max_stack: u16,
+    max_locals: u16,
+    code: Bytecode,
+    exception_table: Box<[ExceptionTableEntry]>,
+    attributes: Box<[AttributeInfo]>,
+}
+
+impl CodeAttributeData {
+    fn from_reader(reader: &mut dyn Read, pool: &Box<[ConstantPoolInfo]>) -> Result<Self, Error> {
+        let max_stack  = read_u16(reader)?;
+        let max_locals = read_u16(reader)?;
+
+        let code_length = read_u32(reader)?;
+        let code        = read_buffer(reader, code_length.try_into()?)?;
+
+        let exception_length = read_u16(reader)?;
+        let exception_table  = {
+            let mut v = Vec::with_capacity(exception_length.into());
+            
+            for _i in 0..exception_length {
+                v.push(ExceptionTableEntry::from_reader(reader)?);
+            }
+
+            v.into_boxed_slice()
+        };
+
+        let attributes = AttributeInfo::array_from_reader(reader, pool, false)?;
+
+        Ok(
+            CodeAttributeData {
+                max_stack,
+                max_locals,
+                code: Bytecode { code },
+                exception_table,
+                attributes
+            }
+        )
+    }
+}
+
+#[derive(Debug)] 
+pub struct SourceFileAttributeData {
+    source_file_index: u16,
+}
+
+impl SourceFileAttributeData {
+    fn from_reader(reader: &mut dyn Read) -> Result<Self, Error> {
+        Ok(
+            SourceFileAttributeData {
+                source_file_index: read_u16(reader)?,
+            }
+        )
+    }
+}
+
+#[derive(Debug)] 
+pub struct SignatureAttributeData {
+    signature_index: u16,
+}
+
+impl SignatureAttributeData {
+    fn from_reader(reader: &mut dyn Read) -> Result<Self, Error> {
+        Ok(
+            SignatureAttributeData {
+                signature_index: read_u16(reader)?,
+            }
+        )
+    }
+}
+
+#[derive(Debug)] 
+pub struct InnerClassesAttributeEntry {
+    inner_class_info_index: u16,
+    outer_class_info_index: u16,
+    inner_name_index: u16,
+    outer_name_index: u16,
+}
+
+impl InnerClassesAttributeEntry {
+    fn from_reader(reader: &mut dyn Read) -> Result<Self, Error> {
+        Ok(
+            InnerClassesAttributeEntry {
+                inner_class_info_index: read_u16(reader)?,
+                outer_class_info_index: read_u16(reader)?,
+                inner_name_index: read_u16(reader)?,
+                outer_name_index: read_u16(reader)?,
+            }
+        )
+    }
+}
+
+#[derive(Debug)] 
+pub struct InnerClassesAttributeData {
+    classes: Box<[InnerClassesAttributeEntry]>
+}
+
+impl InnerClassesAttributeData {
+    fn from_reader(reader: &mut dyn Read) -> Result<Self, Error> {
+        Ok(
+            InnerClassesAttributeData {
+                classes: {
+                    let length = read_u16(reader)?;
+                    let mut v = Vec::with_capacity(length.into());
+
+                    for _i in 0..length {
+                        v.push(InnerClassesAttributeEntry::from_reader(reader)?);
+                    }
+
+                    v.into_boxed_slice()
+                }
+            }
+        )
+    }
+}
+
+#[derive(Debug)] 
+pub struct NestMembersAttributeData {
+    class_indices: Box<[u16]>
+}
+
+impl NestMembersAttributeData {
+    fn from_reader(reader: &mut dyn Read) -> Result<Self, Error> {
+        Ok(
+            NestMembersAttributeData {
+                class_indices: {
+                    let length = read_u16(reader)?;
+                    let mut v = Vec::with_capacity(length.into());
+
+                    for _i in 0..length {
+                        v.push(read_u16(reader)?);
+                    }
+
+                    v.into_boxed_slice()
+                }
+            }
+        )
+    }
+}
+
 #[derive(Debug)] 
 pub enum AttributeData {
+    Code(CodeAttributeData),
+    Signature(SignatureAttributeData),
+    NestMembers(NestMembersAttributeData),
+    SourceFile(SourceFileAttributeData),
+    InnerClasses(InnerClassesAttributeData),
     ConstantValue(ConstantValueAttributeData),
     LineNumberTable(LineNumberTableAttributeData),
-    UnknownAttribute(UnknownAttributeData),
+    Unknown(UnknownAttributeData),
 }
 
 #[derive(Debug)] 
@@ -544,22 +712,21 @@ pub struct AttributeInfo {
 }
 
 impl AttributeInfo {
-    fn array_from_reader(reader: &mut dyn Read, pool: &Box<[ConstantPoolInfo]>) -> Result<Box<[Self]>, Error> {
+    fn array_from_reader(reader: &mut dyn Read, pool: &Box<[ConstantPoolInfo]>, allow_code_attr: bool) -> Result<Box<[Self]>, Error> {
        let length = read_u16(reader)?;
        let mut attr_vec = Vec::with_capacity(length.into());
 
        for _i in 0..length {
-            let attribute = AttributeInfo::from_reader(reader, &pool)?;
-            println!("{:#?}", attribute);
+            let attribute = AttributeInfo::from_reader(reader, &pool, allow_code_attr)?;
             attr_vec.push(attribute);
        }
 
        Ok(attr_vec.into_boxed_slice())
     }
 
-    fn from_reader(reader: &mut dyn Read, pool: &Box<[ConstantPoolInfo]>) -> Result<Self, Error> {
-        let attribute_name_index: u16   = read_u16(reader)?;
-        let attribute_byte_size:  usize = read_u32(reader)?.try_into()?;
+    fn from_reader(reader: &mut dyn Read, pool: &Box<[ConstantPoolInfo]>, allow_code_attr: bool) -> Result<Self, Error> {
+        let attribute_name_index: u16   = read_u16(reader)? - 1;
+        let _attribute_byte_size: usize = read_u32(reader)?.try_into()?;
 
         let data = {
             let name_entry = &pool[attribute_name_index as usize];
@@ -569,19 +736,35 @@ impl AttributeInfo {
             };
 
             match &utf8[..] {
-//               "ConstantValue" => AttributeData::ConstantValue(
-//                   ConstantValueAttributeData {
-//                       constant_value_index: read_u16(reader)?,
-//                   }
-//               ),
-//
-//               "LineNumberTable" => AttributeData::LineNumberTable(
-//                   LineNumberTableAttributeData::from_reader(reader)?
-//               ),
+               "ConstantValue" => AttributeData::ConstantValue(
+                   ConstantValueAttributeData {
+                       constant_value_index: read_u16(reader)?,
+                   }
+               ),
 
-                &_ => AttributeData::UnknownAttribute(
+               "LineNumberTable" => AttributeData::LineNumberTable(
+                   LineNumberTableAttributeData::from_reader(reader)?
+               ),
+
+               "Code" => if allow_code_attr { 
+                   AttributeData::Code(
+                    CodeAttributeData::from_reader(reader, pool)?
+                    ) 
+               } else {
+                   return Err(Error::BadFileError("Nested Code attributes are forbidden.".to_string()));
+               },
+
+               "SourceFile" => AttributeData::SourceFile(SourceFileAttributeData::from_reader(reader)?),
+
+               "Signature" =>  AttributeData::Signature(SignatureAttributeData::from_reader(reader)?),
+
+               "InnerClasses" =>  AttributeData::InnerClasses(InnerClassesAttributeData::from_reader(reader)?),
+
+               "NestMembers" => AttributeData::NestMembers(NestMembersAttributeData::from_reader(reader)?),
+
+                &_ => AttributeData::Unknown(
                     UnknownAttributeData {
-                        info: read_buffer(reader, attribute_byte_size)?,
+                        info: read_buffer(reader, _attribute_byte_size)?,
                     }
                 )
             }
@@ -611,7 +794,7 @@ impl MethodInfo {
                 access_flags: AccessFlagMask { mask: read_u16(reader)? },
                 name_index: read_u16(reader)?,
                 descriptor_index: read_u16(reader)?,
-                attributes: AttributeInfo::array_from_reader(reader, pool)?
+                attributes: AttributeInfo::array_from_reader(reader, pool, true)?
             }
         )
     }

src/main.rs

@@ -1,9 +1,10 @@
 use std::fs::File;
 
 mod classfile;
+mod bytecode;
 
 fn main() {
-    let class_file = classfile::JavaClassFile::new(&mut File::open("Main.class").unwrap()).unwrap();
+    let class_file = classfile::JavaClassFile::new(&mut File::open("class/HashMap.class").unwrap()).unwrap();
 
     println!("{:#?}", class_file);
 }