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use std::fmt;
use crate::error::*;
use crate::header::{AccessFlags, Version};
use crate::reader::{
cpool::{self, ConstantPool},
decoding::*,
items::{Field, Method},
Attribute,
};
#[derive(Clone)]
pub struct Class<'input> {
version: Version,
pool: ConstantPool<'input>,
access_flags: AccessFlags,
this_class: cpool::Index<cpool::Class<'input>>,
super_class: Option<cpool::Index<cpool::Class<'input>>>,
interfaces: DecodeMany<'input, cpool::Index<cpool::Class<'input>>, u16>,
fields: DecodeMany<'input, Field<'input>, u16>,
methods: DecodeMany<'input, Method<'input>, u16>,
attributes: DecodeMany<'input, Attribute<'input>, u16>,
buffer_size: usize,
}
impl<'input> Class<'input> {
/// Initializes a class reader.
///
/// ```no_run
/// use noak::reader::Class;
///
/// # let data = &[];
/// let mut class = Class::new(data)?;
/// # Ok::<(), noak::error::DecodeError>(())
/// ```
pub fn new(v: &'input [u8]) -> Result<Class<'input>, DecodeError> {
let mut decoder = Decoder::new(v, Context::Start);
let version = read_header(&mut decoder)?;
decoder.set_context(Context::ConstantPool);
let pool = decoder.read()?;
decoder.set_context(Context::ClassInfo);
let access_flags = decoder.read()?;
let this_class = decoder.read()?;
let super_class = decoder.read()?;
decoder.set_context(Context::Interfaces);
let interfaces = decoder.read()?;
decoder.set_context(Context::Fields);
let fields = decoder.read()?;
decoder.set_context(Context::Methods);
let methods = decoder.read()?;
decoder.set_context(Context::Attributes);
let attributes = decoder.read()?;
let buffer_size = decoder.file_position();
Ok(Class {
version,
pool,
access_flags,
this_class,
super_class,
interfaces,
fields,
methods,
attributes,
buffer_size,
})
}
/// Returns the class version.
///
/// ```no_run
/// use noak::{Version, reader::Class};
///
/// # let data = &[];
/// let mut class = Class::new(data)?;
/// assert_eq!(class.version(), Version::latest());
/// # Ok::<(), noak::error::DecodeError>(())
/// ```
#[must_use]
pub fn version(&self) -> Version {
self.version
}
/// Returns the constant pool of this class.
///
/// ```no_run
/// use noak::reader::{cpool, Class};
///
/// # let data = &[];
/// # let index = cpool::Index::new(10)?;
/// let mut class = Class::new(data)?;
///
/// let item: &cpool::Utf8 = class.pool().get(index)?;
/// println!("Item: {}", item.content.display());
/// # Ok::<(), noak::error::DecodeError>(())
/// ```
pub fn pool(&self) -> &ConstantPool<'input> {
&self.pool
}
/// Returns the access flags of the class.
///
/// The flags returned may not be valid in this context.
///
/// ```no_run
/// use noak::reader::Class;
/// use noak::AccessFlags;
///
/// # let data = &[];
/// let mut class = Class::new(data)?;
/// let flags = class.access_flags();
/// assert!(flags.contains(AccessFlags::PUBLIC | AccessFlags::SUPER));
///
/// # Ok::<(), noak::error::DecodeError>(())
/// ```
pub fn access_flags(&self) -> AccessFlags {
self.access_flags
}
/// Returns the index of this class name.
///
/// ```no_run
/// use noak::reader::Class;
/// use noak::AccessFlags;
///
/// # let data = &[];
/// let mut class = Class::new(data)?;
/// let this_class = class.this_class();
/// println!("Class: {}", class.pool().retrieve(this_class)?.name.display());
/// # Ok::<(), noak::error::DecodeError>(())
/// ```
pub fn this_class(&self) -> cpool::Index<cpool::Class<'input>> {
self.this_class
}
pub fn super_class(&self) -> Option<cpool::Index<cpool::Class<'input>>> {
self.super_class
}
/// Returns an iterator over the interface indices into the constant pool.
///
/// ```no_run
/// use noak::reader::Class;
///
/// # let data = &[];
/// let mut class = Class::new(data)?;
/// for interface in class.interfaces() {
/// let interface = interface?;
/// println!("Interface: {}", class.pool().retrieve(interface)?.name.display());
/// }
/// # Ok::<(), noak::error::DecodeError>(())
/// ```
pub fn interfaces(&self) -> DecodeMany<'input, cpool::Index<cpool::Class<'input>>, u16> {
self.interfaces.clone()
}
/// Returns an iterator over the fields of this class.
///
/// ```no_run
/// use noak::reader::Class;
///
/// # let data = &[];
/// let mut class = Class::new(data)?;
/// for field in class.fields() {
/// let field = field?;
/// println!("Field name: {}", class.pool().retrieve(field.name())?.display());
/// }
/// # Ok::<(), noak::error::DecodeError>(())
/// ```
pub fn fields(&self) -> DecodeMany<'input, Field<'input>, u16> {
self.fields.clone()
}
/// Returns an iterator over the methods of this class.
///
/// ```no_run
/// use noak::reader::Class;
///
/// # let data = &[];
/// let mut class = Class::new(data)?;
/// for method in class.methods() {
/// let method = method?;
/// println!("Method name: {}", class.pool().retrieve(method.name())?.display());
/// }
/// # Ok::<(), noak::error::DecodeError>(())
/// ```
pub fn methods(&self) -> DecodeMany<'input, Method<'input>, u16> {
self.methods.clone()
}
/// Returns an iterator over the attributes of this class.
///
/// ```no_run
/// use noak::reader::{AttributeContent, Class};
///
/// # let data = &[];
/// let mut class = Class::new(data)?;
/// for attribute in class.attributes() {
/// let attribute = attribute?;
/// match attribute.read_content(class.pool())? {
/// AttributeContent::Deprecated(_) => println!("Class is deprecated"),
/// _ => {}
/// }
/// }
/// # Ok::<(), noak::error::DecodeError>(())
/// ```
pub fn attributes(&self) -> DecodeMany<'input, Attribute<'input>, u16> {
self.attributes.clone()
}
/// The number of bytes used by the class file.
pub fn buffer_size(&self) -> usize {
self.buffer_size
}
}
impl<'input> fmt::Debug for Class<'input> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Class").finish()
}
}
fn read_header(decoder: &mut Decoder<'_>) -> Result<Version, DecodeError> {
let magic: u32 = decoder.read()?;
if magic == 0xCAFE_BABE {
let minor = decoder.read()?;
let major = decoder.read()?;
Ok(Version { major, minor })
} else {
Err(DecodeError::from_decoder(DecodeErrorKind::InvalidPrefix, decoder))
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn valid_header() {
#[rustfmt::skip]
let mut decoder = Decoder::new(&[
// magic bytes
0xCA, 0xFE, 0xBA, 0xBE,
// minor version
0x00, 0x00,
// major version
0x00, 0x38,
], Context::Start);
let version = read_header(&mut decoder).unwrap();
assert_eq!(version, Version { major: 0x38, minor: 0 });
}
#[test]
fn invalid_header() {
#[rustfmt::skip]
let mut decoder = Decoder::new(&[
// invalid magic bytes
0xBE, 0xBA, 0xFE, 0xCA,
], Context::Start);
assert!(read_header(&mut decoder).is_err());
}
}