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Diffstat (limited to 'vendor/object/src/write/mod.rs')
| -rw-r--r-- | vendor/object/src/write/mod.rs | 961 |
1 files changed, 961 insertions, 0 deletions
diff --git a/vendor/object/src/write/mod.rs b/vendor/object/src/write/mod.rs new file mode 100644 index 0000000..cea4d2e --- /dev/null +++ b/vendor/object/src/write/mod.rs @@ -0,0 +1,961 @@ +//! Interface for writing object files. + +use alloc::borrow::Cow; +use alloc::string::String; +use alloc::vec::Vec; +use core::{fmt, result, str}; +#[cfg(not(feature = "std"))] +use hashbrown::HashMap; +#[cfg(feature = "std")] +use std::{boxed::Box, collections::HashMap, error, io}; + +use crate::endian::{Endianness, U32, U64}; +use crate::{ + Architecture, BinaryFormat, ComdatKind, FileFlags, RelocationEncoding, RelocationKind, + SectionFlags, SectionKind, SubArchitecture, SymbolFlags, SymbolKind, SymbolScope, +}; + +#[cfg(feature = "coff")] +pub mod coff; +#[cfg(feature = "coff")] +pub use coff::CoffExportStyle; + +#[cfg(feature = "elf")] +pub mod elf; + +#[cfg(feature = "macho")] +mod macho; +#[cfg(feature = "macho")] +pub use macho::MachOBuildVersion; + +#[cfg(feature = "pe")] +pub mod pe; + +#[cfg(feature = "xcoff")] +mod xcoff; + +mod string; +pub use string::StringId; + +mod util; +pub use util::*; + +/// The error type used within the write module. +#[derive(Debug, Clone, PartialEq, Eq)] +pub struct Error(String); + +impl fmt::Display for Error { + #[inline] + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.write_str(&self.0) + } +} + +#[cfg(feature = "std")] +impl error::Error for Error {} + +/// The result type used within the write module. +pub type Result<T> = result::Result<T, Error>; + +/// A writable relocatable object file. +#[derive(Debug)] +pub struct Object<'a> { + format: BinaryFormat, + architecture: Architecture, + sub_architecture: Option<SubArchitecture>, + endian: Endianness, + sections: Vec<Section<'a>>, + standard_sections: HashMap<StandardSection, SectionId>, + symbols: Vec<Symbol>, + symbol_map: HashMap<Vec<u8>, SymbolId>, + stub_symbols: HashMap<SymbolId, SymbolId>, + comdats: Vec<Comdat>, + /// File flags that are specific to each file format. + pub flags: FileFlags, + /// The symbol name mangling scheme. + pub mangling: Mangling, + /// Mach-O "_tlv_bootstrap" symbol. + tlv_bootstrap: Option<SymbolId>, + /// Mach-O CPU subtype. + #[cfg(feature = "macho")] + macho_cpu_subtype: Option<u32>, + #[cfg(feature = "macho")] + macho_build_version: Option<MachOBuildVersion>, +} + +impl<'a> Object<'a> { + /// Create an empty object file. + pub fn new(format: BinaryFormat, architecture: Architecture, endian: Endianness) -> Object<'a> { + Object { + format, + architecture, + sub_architecture: None, + endian, + sections: Vec::new(), + standard_sections: HashMap::new(), + symbols: Vec::new(), + symbol_map: HashMap::new(), + stub_symbols: HashMap::new(), + comdats: Vec::new(), + flags: FileFlags::None, + mangling: Mangling::default(format, architecture), + tlv_bootstrap: None, + #[cfg(feature = "macho")] + macho_cpu_subtype: None, + #[cfg(feature = "macho")] + macho_build_version: None, + } + } + + /// Return the file format. + #[inline] + pub fn format(&self) -> BinaryFormat { + self.format + } + + /// Return the architecture. + #[inline] + pub fn architecture(&self) -> Architecture { + self.architecture + } + + /// Return the sub-architecture. + #[inline] + pub fn sub_architecture(&self) -> Option<SubArchitecture> { + self.sub_architecture + } + + /// Specify the sub-architecture. + pub fn set_sub_architecture(&mut self, sub_architecture: Option<SubArchitecture>) { + self.sub_architecture = sub_architecture; + } + + /// Return the current mangling setting. + #[inline] + pub fn mangling(&self) -> Mangling { + self.mangling + } + + /// Specify the mangling setting. + #[inline] + pub fn set_mangling(&mut self, mangling: Mangling) { + self.mangling = mangling; + } + + /// Return the name for a standard segment. + /// + /// This will vary based on the file format. + #[allow(unused_variables)] + pub fn segment_name(&self, segment: StandardSegment) -> &'static [u8] { + match self.format { + #[cfg(feature = "coff")] + BinaryFormat::Coff => &[], + #[cfg(feature = "elf")] + BinaryFormat::Elf => &[], + #[cfg(feature = "macho")] + BinaryFormat::MachO => self.macho_segment_name(segment), + _ => unimplemented!(), + } + } + + /// Get the section with the given `SectionId`. + #[inline] + pub fn section(&self, section: SectionId) -> &Section<'a> { + &self.sections[section.0] + } + + /// Mutably get the section with the given `SectionId`. + #[inline] + pub fn section_mut(&mut self, section: SectionId) -> &mut Section<'a> { + &mut self.sections[section.0] + } + + /// Set the data for an existing section. + /// + /// Must not be called for sections that already have data, or that contain uninitialized data. + pub fn set_section_data<T>(&mut self, section: SectionId, data: T, align: u64) + where + T: Into<Cow<'a, [u8]>>, + { + self.sections[section.0].set_data(data, align) + } + + /// Append data to an existing section. Returns the section offset of the data. + pub fn append_section_data(&mut self, section: SectionId, data: &[u8], align: u64) -> u64 { + self.sections[section.0].append_data(data, align) + } + + /// Append zero-initialized data to an existing section. Returns the section offset of the data. + pub fn append_section_bss(&mut self, section: SectionId, size: u64, align: u64) -> u64 { + self.sections[section.0].append_bss(size, align) + } + + /// Return the `SectionId` of a standard section. + /// + /// If the section doesn't already exist then it is created. + pub fn section_id(&mut self, section: StandardSection) -> SectionId { + self.standard_sections + .get(§ion) + .cloned() + .unwrap_or_else(|| { + let (segment, name, kind, flags) = self.section_info(section); + let id = self.add_section(segment.to_vec(), name.to_vec(), kind); + self.section_mut(id).flags = flags; + id + }) + } + + /// Add a new section and return its `SectionId`. + /// + /// This also creates a section symbol. + pub fn add_section(&mut self, segment: Vec<u8>, name: Vec<u8>, kind: SectionKind) -> SectionId { + let id = SectionId(self.sections.len()); + self.sections.push(Section { + segment, + name, + kind, + size: 0, + align: 1, + data: Cow::Borrowed(&[]), + relocations: Vec::new(), + symbol: None, + flags: SectionFlags::None, + }); + + // Add to self.standard_sections if required. This may match multiple standard sections. + let section = &self.sections[id.0]; + for standard_section in StandardSection::all() { + if !self.standard_sections.contains_key(standard_section) { + let (segment, name, kind, _flags) = self.section_info(*standard_section); + if segment == &*section.segment && name == &*section.name && kind == section.kind { + self.standard_sections.insert(*standard_section, id); + } + } + } + + id + } + + fn section_info( + &self, + section: StandardSection, + ) -> (&'static [u8], &'static [u8], SectionKind, SectionFlags) { + match self.format { + #[cfg(feature = "coff")] + BinaryFormat::Coff => self.coff_section_info(section), + #[cfg(feature = "elf")] + BinaryFormat::Elf => self.elf_section_info(section), + #[cfg(feature = "macho")] + BinaryFormat::MachO => self.macho_section_info(section), + #[cfg(feature = "xcoff")] + BinaryFormat::Xcoff => self.xcoff_section_info(section), + _ => unimplemented!(), + } + } + + /// Add a subsection. Returns the `SectionId` and section offset of the data. + pub fn add_subsection( + &mut self, + section: StandardSection, + name: &[u8], + data: &[u8], + align: u64, + ) -> (SectionId, u64) { + let section_id = if self.has_subsections_via_symbols() { + self.set_subsections_via_symbols(); + self.section_id(section) + } else { + let (segment, name, kind, flags) = self.subsection_info(section, name); + let id = self.add_section(segment.to_vec(), name, kind); + self.section_mut(id).flags = flags; + id + }; + let offset = self.append_section_data(section_id, data, align); + (section_id, offset) + } + + fn has_subsections_via_symbols(&self) -> bool { + match self.format { + BinaryFormat::Coff | BinaryFormat::Elf | BinaryFormat::Xcoff => false, + BinaryFormat::MachO => true, + _ => unimplemented!(), + } + } + + fn set_subsections_via_symbols(&mut self) { + match self.format { + #[cfg(feature = "macho")] + BinaryFormat::MachO => self.macho_set_subsections_via_symbols(), + _ => unimplemented!(), + } + } + + fn subsection_info( + &self, + section: StandardSection, + value: &[u8], + ) -> (&'static [u8], Vec<u8>, SectionKind, SectionFlags) { + let (segment, section, kind, flags) = self.section_info(section); + let name = self.subsection_name(section, value); + (segment, name, kind, flags) + } + + #[allow(unused_variables)] + fn subsection_name(&self, section: &[u8], value: &[u8]) -> Vec<u8> { + debug_assert!(!self.has_subsections_via_symbols()); + match self.format { + #[cfg(feature = "coff")] + BinaryFormat::Coff => self.coff_subsection_name(section, value), + #[cfg(feature = "elf")] + BinaryFormat::Elf => self.elf_subsection_name(section, value), + _ => unimplemented!(), + } + } + + /// Get the COMDAT section group with the given `ComdatId`. + #[inline] + pub fn comdat(&self, comdat: ComdatId) -> &Comdat { + &self.comdats[comdat.0] + } + + /// Mutably get the COMDAT section group with the given `ComdatId`. + #[inline] + pub fn comdat_mut(&mut self, comdat: ComdatId) -> &mut Comdat { + &mut self.comdats[comdat.0] + } + + /// Add a new COMDAT section group and return its `ComdatId`. + pub fn add_comdat(&mut self, comdat: Comdat) -> ComdatId { + let comdat_id = ComdatId(self.comdats.len()); + self.comdats.push(comdat); + comdat_id + } + + /// Get the `SymbolId` of the symbol with the given name. + pub fn symbol_id(&self, name: &[u8]) -> Option<SymbolId> { + self.symbol_map.get(name).cloned() + } + + /// Get the symbol with the given `SymbolId`. + #[inline] + pub fn symbol(&self, symbol: SymbolId) -> &Symbol { + &self.symbols[symbol.0] + } + + /// Mutably get the symbol with the given `SymbolId`. + #[inline] + pub fn symbol_mut(&mut self, symbol: SymbolId) -> &mut Symbol { + &mut self.symbols[symbol.0] + } + + /// Add a new symbol and return its `SymbolId`. + pub fn add_symbol(&mut self, mut symbol: Symbol) -> SymbolId { + // Defined symbols must have a scope. + debug_assert!(symbol.is_undefined() || symbol.scope != SymbolScope::Unknown); + if symbol.kind == SymbolKind::Section { + // There can only be one section symbol, but update its flags, since + // the automatically generated section symbol will have none. + let symbol_id = self.section_symbol(symbol.section.id().unwrap()); + if symbol.flags != SymbolFlags::None { + self.symbol_mut(symbol_id).flags = symbol.flags; + } + return symbol_id; + } + if !symbol.name.is_empty() + && (symbol.kind == SymbolKind::Text + || symbol.kind == SymbolKind::Data + || symbol.kind == SymbolKind::Tls) + { + let unmangled_name = symbol.name.clone(); + if let Some(prefix) = self.mangling.global_prefix() { + symbol.name.insert(0, prefix); + } + let symbol_id = self.add_raw_symbol(symbol); + self.symbol_map.insert(unmangled_name, symbol_id); + symbol_id + } else { + self.add_raw_symbol(symbol) + } + } + + fn add_raw_symbol(&mut self, symbol: Symbol) -> SymbolId { + let symbol_id = SymbolId(self.symbols.len()); + self.symbols.push(symbol); + symbol_id + } + + /// Return true if the file format supports `StandardSection::UninitializedTls`. + #[inline] + pub fn has_uninitialized_tls(&self) -> bool { + self.format != BinaryFormat::Coff + } + + /// Return true if the file format supports `StandardSection::Common`. + #[inline] + pub fn has_common(&self) -> bool { + self.format == BinaryFormat::MachO + } + + /// Add a new common symbol and return its `SymbolId`. + /// + /// For Mach-O, this appends the symbol to the `__common` section. + pub fn add_common_symbol(&mut self, mut symbol: Symbol, size: u64, align: u64) -> SymbolId { + if self.has_common() { + let symbol_id = self.add_symbol(symbol); + let section = self.section_id(StandardSection::Common); + self.add_symbol_bss(symbol_id, section, size, align); + symbol_id + } else { + symbol.section = SymbolSection::Common; + symbol.size = size; + self.add_symbol(symbol) + } + } + + /// Add a new file symbol and return its `SymbolId`. + pub fn add_file_symbol(&mut self, name: Vec<u8>) -> SymbolId { + self.add_raw_symbol(Symbol { + name, + value: 0, + size: 0, + kind: SymbolKind::File, + scope: SymbolScope::Compilation, + weak: false, + section: SymbolSection::None, + flags: SymbolFlags::None, + }) + } + + /// Get the symbol for a section. + pub fn section_symbol(&mut self, section_id: SectionId) -> SymbolId { + let section = &mut self.sections[section_id.0]; + if let Some(symbol) = section.symbol { + return symbol; + } + let name = if self.format == BinaryFormat::Coff { + section.name.clone() + } else { + Vec::new() + }; + let symbol_id = SymbolId(self.symbols.len()); + self.symbols.push(Symbol { + name, + value: 0, + size: 0, + kind: SymbolKind::Section, + scope: SymbolScope::Compilation, + weak: false, + section: SymbolSection::Section(section_id), + flags: SymbolFlags::None, + }); + section.symbol = Some(symbol_id); + symbol_id + } + + /// Append data to an existing section, and update a symbol to refer to it. + /// + /// For Mach-O, this also creates a `__thread_vars` entry for TLS symbols, and the + /// symbol will indirectly point to the added data via the `__thread_vars` entry. + /// + /// Returns the section offset of the data. + pub fn add_symbol_data( + &mut self, + symbol_id: SymbolId, + section: SectionId, + data: &[u8], + align: u64, + ) -> u64 { + let offset = self.append_section_data(section, data, align); + self.set_symbol_data(symbol_id, section, offset, data.len() as u64); + offset + } + + /// Append zero-initialized data to an existing section, and update a symbol to refer to it. + /// + /// For Mach-O, this also creates a `__thread_vars` entry for TLS symbols, and the + /// symbol will indirectly point to the added data via the `__thread_vars` entry. + /// + /// Returns the section offset of the data. + pub fn add_symbol_bss( + &mut self, + symbol_id: SymbolId, + section: SectionId, + size: u64, + align: u64, + ) -> u64 { + let offset = self.append_section_bss(section, size, align); + self.set_symbol_data(symbol_id, section, offset, size); + offset + } + + /// Update a symbol to refer to the given data within a section. + /// + /// For Mach-O, this also creates a `__thread_vars` entry for TLS symbols, and the + /// symbol will indirectly point to the data via the `__thread_vars` entry. + #[allow(unused_mut)] + pub fn set_symbol_data( + &mut self, + mut symbol_id: SymbolId, + section: SectionId, + offset: u64, + size: u64, + ) { + // Defined symbols must have a scope. + debug_assert!(self.symbol(symbol_id).scope != SymbolScope::Unknown); + match self.format { + #[cfg(feature = "macho")] + BinaryFormat::MachO => symbol_id = self.macho_add_thread_var(symbol_id), + _ => {} + } + let symbol = self.symbol_mut(symbol_id); + symbol.value = offset; + symbol.size = size; + symbol.section = SymbolSection::Section(section); + } + + /// Convert a symbol to a section symbol and offset. + /// + /// Returns `None` if the symbol does not have a section. + pub fn symbol_section_and_offset(&mut self, symbol_id: SymbolId) -> Option<(SymbolId, u64)> { + let symbol = self.symbol(symbol_id); + if symbol.kind == SymbolKind::Section { + return Some((symbol_id, 0)); + } + let symbol_offset = symbol.value; + let section = symbol.section.id()?; + let section_symbol = self.section_symbol(section); + Some((section_symbol, symbol_offset)) + } + + /// Add a relocation to a section. + /// + /// Relocations must only be added after the referenced symbols have been added + /// and defined (if applicable). + pub fn add_relocation(&mut self, section: SectionId, mut relocation: Relocation) -> Result<()> { + let addend = match self.format { + #[cfg(feature = "coff")] + BinaryFormat::Coff => self.coff_fixup_relocation(&mut relocation), + #[cfg(feature = "elf")] + BinaryFormat::Elf => self.elf_fixup_relocation(&mut relocation)?, + #[cfg(feature = "macho")] + BinaryFormat::MachO => self.macho_fixup_relocation(&mut relocation), + #[cfg(feature = "xcoff")] + BinaryFormat::Xcoff => self.xcoff_fixup_relocation(&mut relocation), + _ => unimplemented!(), + }; + if addend != 0 { + self.write_relocation_addend(section, &relocation, addend)?; + } + self.sections[section.0].relocations.push(relocation); + Ok(()) + } + + fn write_relocation_addend( + &mut self, + section: SectionId, + relocation: &Relocation, + addend: i64, + ) -> Result<()> { + let data = self.sections[section.0].data_mut(); + let offset = relocation.offset as usize; + match relocation.size { + 32 => data.write_at(offset, &U32::new(self.endian, addend as u32)), + 64 => data.write_at(offset, &U64::new(self.endian, addend as u64)), + _ => { + return Err(Error(format!( + "unimplemented relocation addend {:?}", + relocation + ))); + } + } + .map_err(|_| { + Error(format!( + "invalid relocation offset {}+{} (max {})", + relocation.offset, + relocation.size, + data.len() + )) + }) + } + + /// Write the object to a `Vec`. + pub fn write(&self) -> Result<Vec<u8>> { + let mut buffer = Vec::new(); + self.emit(&mut buffer)?; + Ok(buffer) + } + + /// Write the object to a `Write` implementation. + /// + /// Also flushes the writer. + /// + /// It is advisable to use a buffered writer like [`BufWriter`](std::io::BufWriter) + /// instead of an unbuffered writer like [`File`](std::fs::File). + #[cfg(feature = "std")] + pub fn write_stream<W: io::Write>(&self, w: W) -> result::Result<(), Box<dyn error::Error>> { + let mut stream = StreamingBuffer::new(w); + self.emit(&mut stream)?; + stream.result()?; + stream.into_inner().flush()?; + Ok(()) + } + + /// Write the object to a `WritableBuffer`. + pub fn emit(&self, buffer: &mut dyn WritableBuffer) -> Result<()> { + match self.format { + #[cfg(feature = "coff")] + BinaryFormat::Coff => self.coff_write(buffer), + #[cfg(feature = "elf")] + BinaryFormat::Elf => self.elf_write(buffer), + #[cfg(feature = "macho")] + BinaryFormat::MachO => self.macho_write(buffer), + #[cfg(feature = "xcoff")] + BinaryFormat::Xcoff => self.xcoff_write(buffer), + _ => unimplemented!(), + } + } +} + +/// A standard segment kind. +#[allow(missing_docs)] +#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] +#[non_exhaustive] +pub enum StandardSegment { + Text, + Data, + Debug, +} + +/// A standard section kind. +#[allow(missing_docs)] +#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] +#[non_exhaustive] +pub enum StandardSection { + Text, + Data, + ReadOnlyData, + ReadOnlyDataWithRel, + ReadOnlyString, + UninitializedData, + Tls, + /// Zero-fill TLS initializers. Unsupported for COFF. + UninitializedTls, + /// TLS variable structures. Only supported for Mach-O. + TlsVariables, + /// Common data. Only supported for Mach-O. + Common, + /// Notes for GNU properties. Only supported for ELF. + GnuProperty, +} + +impl StandardSection { + /// Return the section kind of a standard section. + pub fn kind(self) -> SectionKind { + match self { + StandardSection::Text => SectionKind::Text, + StandardSection::Data => SectionKind::Data, + StandardSection::ReadOnlyData => SectionKind::ReadOnlyData, + StandardSection::ReadOnlyDataWithRel => SectionKind::ReadOnlyDataWithRel, + StandardSection::ReadOnlyString => SectionKind::ReadOnlyString, + StandardSection::UninitializedData => SectionKind::UninitializedData, + StandardSection::Tls => SectionKind::Tls, + StandardSection::UninitializedTls => SectionKind::UninitializedTls, + StandardSection::TlsVariables => SectionKind::TlsVariables, + StandardSection::Common => SectionKind::Common, + StandardSection::GnuProperty => SectionKind::Note, + } + } + + // TODO: remembering to update this is error-prone, can we do better? + fn all() -> &'static [StandardSection] { + &[ + StandardSection::Text, + StandardSection::Data, + StandardSection::ReadOnlyData, + StandardSection::ReadOnlyDataWithRel, + StandardSection::ReadOnlyString, + StandardSection::UninitializedData, + StandardSection::Tls, + StandardSection::UninitializedTls, + StandardSection::TlsVariables, + StandardSection::Common, + StandardSection::GnuProperty, + ] + } +} + +/// An identifier used to reference a section. +#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] +pub struct SectionId(usize); + +/// A section in an object file. +#[derive(Debug)] +pub struct Section<'a> { + segment: Vec<u8>, + name: Vec<u8>, + kind: SectionKind, + size: u64, + align: u64, + data: Cow<'a, [u8]>, + relocations: Vec<Relocation>, + symbol: Option<SymbolId>, + /// Section flags that are specific to each file format. + pub flags: SectionFlags, +} + +impl<'a> Section<'a> { + /// Try to convert the name to a utf8 string. + #[inline] + pub fn name(&self) -> Option<&str> { + str::from_utf8(&self.name).ok() + } + + /// Try to convert the segment to a utf8 string. + #[inline] + pub fn segment(&self) -> Option<&str> { + str::from_utf8(&self.segment).ok() + } + + /// Return true if this section contains zerofill data. + #[inline] + pub fn is_bss(&self) -> bool { + self.kind.is_bss() + } + + /// Set the data for a section. + /// + /// Must not be called for sections that already have data, or that contain uninitialized data. + pub fn set_data<T>(&mut self, data: T, align: u64) + where + T: Into<Cow<'a, [u8]>>, + { + debug_assert!(!self.is_bss()); + debug_assert_eq!(align & (align - 1), 0); + debug_assert!(self.data.is_empty()); + self.data = data.into(); + self.size = self.data.len() as u64; + self.align = align; + } + + /// Append data to a section. + /// + /// Must not be called for sections that contain uninitialized data. + pub fn append_data(&mut self, append_data: &[u8], align: u64) -> u64 { + debug_assert!(!self.is_bss()); + debug_assert_eq!(align & (align - 1), 0); + if self.align < align { + self.align = align; + } + let align = align as usize; + let data = self.data.to_mut(); + let mut offset = data.len(); + if offset & (align - 1) != 0 { + offset += align - (offset & (align - 1)); + data.resize(offset, 0); + } + data.extend_from_slice(append_data); + self.size = data.len() as u64; + offset as u64 + } + + /// Append uninitialized data to a section. + /// + /// Must not be called for sections that contain initialized data. + pub fn append_bss(&mut self, size: u64, align: u64) -> u64 { + debug_assert!(self.is_bss()); + debug_assert_eq!(align & (align - 1), 0); + if self.align < align { + self.align = align; + } + let mut offset = self.size; + if offset & (align - 1) != 0 { + offset += align - (offset & (align - 1)); + self.size = offset; + } + self.size += size; + offset + } + + /// Returns the section as-built so far. + /// + /// This requires that the section is not a bss section. + pub fn data(&self) -> &[u8] { + debug_assert!(!self.is_bss()); + &self.data + } + + /// Returns the section as-built so far. + /// + /// This requires that the section is not a bss section. + pub fn data_mut(&mut self) -> &mut [u8] { + debug_assert!(!self.is_bss()); + self.data.to_mut() + } +} + +/// The section where a symbol is defined. +#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] +#[non_exhaustive] +pub enum SymbolSection { + /// The section is not applicable for this symbol (such as file symbols). + None, + /// The symbol is undefined. + Undefined, + /// The symbol has an absolute value. + Absolute, + /// The symbol is a zero-initialized symbol that will be combined with duplicate definitions. + Common, + /// The symbol is defined in the given section. + Section(SectionId), +} + +impl SymbolSection { + /// Returns the section id for the section where the symbol is defined. + /// + /// May return `None` if the symbol is not defined in a section. + #[inline] + pub fn id(self) -> Option<SectionId> { + if let SymbolSection::Section(id) = self { + Some(id) + } else { + None + } + } +} + +/// An identifier used to reference a symbol. +#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] +pub struct SymbolId(usize); + +/// A symbol in an object file. +#[derive(Debug)] +pub struct Symbol { + /// The name of the symbol. + pub name: Vec<u8>, + /// The value of the symbol. + /// + /// If the symbol defined in a section, then this is the section offset of the symbol. + pub value: u64, + /// The size of the symbol. + pub size: u64, + /// The kind of the symbol. + pub kind: SymbolKind, + /// The scope of the symbol. + pub scope: SymbolScope, + /// Whether the symbol has weak binding. + pub weak: bool, + /// The section containing the symbol. + pub section: SymbolSection, + /// Symbol flags that are specific to each file format. + pub flags: SymbolFlags<SectionId, SymbolId>, +} + +impl Symbol { + /// Try to convert the name to a utf8 string. + #[inline] + pub fn name(&self) -> Option<&str> { + str::from_utf8(&self.name).ok() + } + + /// Return true if the symbol is undefined. + #[inline] + pub fn is_undefined(&self) -> bool { + self.section == SymbolSection::Undefined + } + + /// Return true if the symbol is common data. + /// + /// Note: does not check for `SymbolSection::Section` with `SectionKind::Common`. + #[inline] + pub fn is_common(&self) -> bool { + self.section == SymbolSection::Common + } + + /// Return true if the symbol scope is local. + #[inline] + pub fn is_local(&self) -> bool { + self.scope == SymbolScope::Compilation + } +} + +/// A relocation in an object file. +#[derive(Debug)] +pub struct Relocation { + /// The section offset of the place of the relocation. + pub offset: u64, + /// The size in bits of the place of relocation. + pub size: u8, + /// The operation used to calculate the result of the relocation. + pub kind: RelocationKind, + /// Information about how the result of the relocation operation is encoded in the place. + pub encoding: RelocationEncoding, + /// The symbol referred to by the relocation. + /// + /// This may be a section symbol. + pub symbol: SymbolId, + /// The addend to use in the relocation calculation. + /// + /// This may be in addition to an implicit addend stored at the place of the relocation. + pub addend: i64, +} + +/// An identifier used to reference a COMDAT section group. +#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] +pub struct ComdatId(usize); + +/// A COMDAT section group. +#[derive(Debug)] +pub struct Comdat { + /// The COMDAT selection kind. + /// + /// This determines the way in which the linker resolves multiple definitions of the COMDAT + /// sections. + pub kind: ComdatKind, + /// The COMDAT symbol. + /// + /// If this symbol is referenced, then all sections in the group will be included by the + /// linker. + pub symbol: SymbolId, + /// The sections in the group. + pub sections: Vec<SectionId>, +} + +/// The symbol name mangling scheme. +#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] +#[non_exhaustive] +pub enum Mangling { + /// No symbol mangling. + None, + /// Windows COFF symbol mangling. + Coff, + /// Windows COFF i386 symbol mangling. + CoffI386, + /// ELF symbol mangling. + Elf, + /// Mach-O symbol mangling. + MachO, + /// Xcoff symbol mangling. + Xcoff, +} + +impl Mangling { + /// Return the default symboling mangling for the given format and architecture. + pub fn default(format: BinaryFormat, architecture: Architecture) -> Self { + match (format, architecture) { + (BinaryFormat::Coff, Architecture::I386) => Mangling::CoffI386, + (BinaryFormat::Coff, _) => Mangling::Coff, + (BinaryFormat::Elf, _) => Mangling::Elf, + (BinaryFormat::MachO, _) => Mangling::MachO, + (BinaryFormat::Xcoff, _) => Mangling::Xcoff, + _ => Mangling::None, + } + } + + /// Return the prefix to use for global symbols. + pub fn global_prefix(self) -> Option<u8> { + match self { + Mangling::None | Mangling::Elf | Mangling::Coff | Mangling::Xcoff => None, + Mangling::CoffI386 | Mangling::MachO => Some(b'_'), + } + } +} |