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Diffstat (limited to 'vendor/object/src/write/coff/writer.rs')
| -rw-r--r-- | vendor/object/src/write/coff/writer.rs | 518 |
1 files changed, 518 insertions, 0 deletions
diff --git a/vendor/object/src/write/coff/writer.rs b/vendor/object/src/write/coff/writer.rs new file mode 100644 index 0000000..8c7ada3 --- /dev/null +++ b/vendor/object/src/write/coff/writer.rs @@ -0,0 +1,518 @@ +//! Helper for writing COFF files. +use alloc::string::String; +use alloc::vec::Vec; +use core::mem; + +use crate::endian::{LittleEndian as LE, U16Bytes, U32Bytes, U16, U32}; +use crate::pe; +use crate::write::string::{StringId, StringTable}; +use crate::write::util; +use crate::write::{Error, Result, WritableBuffer}; + +/// A helper for writing COFF files. +/// +/// Writing uses a two phase approach. The first phase builds up all of the information +/// that may need to be known ahead of time: +/// - build string table +/// - reserve section indices +/// - reserve symbol indices +/// - reserve file ranges for headers and sections +/// +/// Some of the information has ordering requirements. For example, strings must be added +/// to the string table before reserving the file range for the string table. There are debug +/// asserts to check some of these requirements. +/// +/// The second phase writes everything out in order. Thus the caller must ensure writing +/// is in the same order that file ranges were reserved. There are debug asserts to assist +/// with checking this. +#[allow(missing_debug_implementations)] +pub struct Writer<'a> { + buffer: &'a mut dyn WritableBuffer, + len: usize, + + section_num: u16, + + symtab_offset: u32, + symtab_num: u32, + + strtab: StringTable<'a>, + strtab_len: usize, + strtab_offset: u32, + strtab_data: Vec<u8>, +} + +impl<'a> Writer<'a> { + /// Create a new `Writer`. + pub fn new(buffer: &'a mut dyn WritableBuffer) -> Self { + Writer { + buffer, + len: 0, + + section_num: 0, + + symtab_offset: 0, + symtab_num: 0, + + strtab: StringTable::default(), + strtab_len: 0, + strtab_offset: 0, + strtab_data: Vec::new(), + } + } + + /// Return the current file length that has been reserved. + pub fn reserved_len(&self) -> usize { + self.len + } + + /// Return the current file length that has been written. + #[allow(clippy::len_without_is_empty)] + pub fn len(&self) -> usize { + self.buffer.len() + } + + /// Reserve a file range with the given size and starting alignment. + /// + /// Returns the aligned offset of the start of the range. + pub fn reserve(&mut self, len: usize, align_start: usize) -> u32 { + if align_start > 1 { + self.len = util::align(self.len, align_start); + } + let offset = self.len; + self.len += len; + offset as u32 + } + + /// Write alignment padding bytes. + pub fn write_align(&mut self, align_start: usize) { + if align_start > 1 { + util::write_align(self.buffer, align_start); + } + } + + /// Write data. + pub fn write(&mut self, data: &[u8]) { + self.buffer.write_bytes(data); + } + + /// Reserve the file range up to the given file offset. + pub fn reserve_until(&mut self, offset: usize) { + debug_assert!(self.len <= offset); + self.len = offset; + } + + /// Write padding up to the given file offset. + pub fn pad_until(&mut self, offset: usize) { + debug_assert!(self.buffer.len() <= offset); + self.buffer.resize(offset); + } + + /// Reserve the range for the file header. + /// + /// This must be at the start of the file. + pub fn reserve_file_header(&mut self) { + debug_assert_eq!(self.len, 0); + self.reserve(mem::size_of::<pe::ImageFileHeader>(), 1); + } + + /// Write the file header. + /// + /// This must be at the start of the file. + /// + /// Fields that can be derived from known information are automatically set by this function. + pub fn write_file_header(&mut self, header: FileHeader) -> Result<()> { + debug_assert_eq!(self.buffer.len(), 0); + + // Start writing. + self.buffer + .reserve(self.len) + .map_err(|_| Error(String::from("Cannot allocate buffer")))?; + + // Write file header. + let header = pe::ImageFileHeader { + machine: U16::new(LE, header.machine), + number_of_sections: U16::new(LE, self.section_num), + time_date_stamp: U32::new(LE, header.time_date_stamp), + pointer_to_symbol_table: U32::new(LE, self.symtab_offset), + number_of_symbols: U32::new(LE, self.symtab_num), + size_of_optional_header: U16::default(), + characteristics: U16::new(LE, header.characteristics), + }; + self.buffer.write(&header); + + Ok(()) + } + + /// Reserve the range for the section headers. + pub fn reserve_section_headers(&mut self, section_num: u16) { + debug_assert_eq!(self.section_num, 0); + self.section_num = section_num; + self.reserve( + section_num as usize * mem::size_of::<pe::ImageSectionHeader>(), + 1, + ); + } + + /// Write a section header. + pub fn write_section_header(&mut self, section: SectionHeader) { + let mut coff_section = pe::ImageSectionHeader { + name: [0; 8], + virtual_size: U32::default(), + virtual_address: U32::default(), + size_of_raw_data: U32::new(LE, section.size_of_raw_data), + pointer_to_raw_data: U32::new(LE, section.pointer_to_raw_data), + pointer_to_relocations: U32::new(LE, section.pointer_to_relocations), + pointer_to_linenumbers: U32::new(LE, section.pointer_to_linenumbers), + number_of_relocations: if section.number_of_relocations > 0xffff { + U16::new(LE, 0xffff) + } else { + U16::new(LE, section.number_of_relocations as u16) + }, + number_of_linenumbers: U16::default(), + characteristics: U32::new(LE, section.characteristics), + }; + match section.name { + Name::Short(name) => coff_section.name = name, + Name::Long(str_id) => { + let mut str_offset = self.strtab.get_offset(str_id); + if str_offset <= 9_999_999 { + let mut name = [0; 7]; + let mut len = 0; + if str_offset == 0 { + name[6] = b'0'; + len = 1; + } else { + while str_offset != 0 { + let rem = (str_offset % 10) as u8; + str_offset /= 10; + name[6 - len] = b'0' + rem; + len += 1; + } + } + coff_section.name = [0; 8]; + coff_section.name[0] = b'/'; + coff_section.name[1..][..len].copy_from_slice(&name[7 - len..]); + } else { + debug_assert!(str_offset as u64 <= 0xf_ffff_ffff); + coff_section.name[0] = b'/'; + coff_section.name[1] = b'/'; + for i in 0..6 { + let rem = (str_offset % 64) as u8; + str_offset /= 64; + let c = match rem { + 0..=25 => b'A' + rem, + 26..=51 => b'a' + rem - 26, + 52..=61 => b'0' + rem - 52, + 62 => b'+', + 63 => b'/', + _ => unreachable!(), + }; + coff_section.name[7 - i] = c; + } + } + } + } + self.buffer.write(&coff_section); + } + + /// Reserve the range for the section data. + /// + /// Returns the aligned offset of the start of the range. + /// Does nothing and returns 0 if the length is zero. + pub fn reserve_section(&mut self, len: usize) -> u32 { + if len == 0 { + return 0; + } + // TODO: not sure what alignment is required here, but this seems to match LLVM + self.reserve(len, 4) + } + + /// Write the alignment bytes prior to section data. + /// + /// This is unneeded if you are using `write_section` or `write_section_zeroes` + /// for the data. + pub fn write_section_align(&mut self) { + util::write_align(self.buffer, 4); + } + + /// Write the section data. + /// + /// Writes alignment bytes prior to the data. + /// Does nothing if the data is empty. + pub fn write_section(&mut self, data: &[u8]) { + if data.is_empty() { + return; + } + self.write_section_align(); + self.buffer.write_bytes(data); + } + + /// Write the section data using zero bytes. + /// + /// Writes alignment bytes prior to the data. + /// Does nothing if the length is zero. + pub fn write_section_zeroes(&mut self, len: usize) { + if len == 0 { + return; + } + self.write_section_align(); + self.buffer.resize(self.buffer.len() + len); + } + + /// Reserve a file range for the given number of relocations. + /// + /// This will automatically reserve an extra relocation if there are more than 0xffff. + /// + /// Returns the offset of the range. + /// Does nothing and returns 0 if the count is zero. + pub fn reserve_relocations(&mut self, mut count: usize) -> u32 { + if count == 0 { + return 0; + } + if count > 0xffff { + count += 1; + } + self.reserve(count * mem::size_of::<pe::ImageRelocation>(), 1) + } + + /// Write a relocation containing the count if required. + /// + /// This should be called before writing the first relocation for a section. + pub fn write_relocations_count(&mut self, count: usize) { + if count > 0xffff { + let coff_relocation = pe::ImageRelocation { + virtual_address: U32Bytes::new(LE, count as u32 + 1), + symbol_table_index: U32Bytes::new(LE, 0), + typ: U16Bytes::new(LE, 0), + }; + self.buffer.write(&coff_relocation); + } + } + + /// Write a relocation. + pub fn write_relocation(&mut self, reloc: Relocation) { + let coff_relocation = pe::ImageRelocation { + virtual_address: U32Bytes::new(LE, reloc.virtual_address), + symbol_table_index: U32Bytes::new(LE, reloc.symbol), + typ: U16Bytes::new(LE, reloc.typ), + }; + self.buffer.write(&coff_relocation); + } + + /// Reserve a symbol table entry. + /// + /// This must be called before [`Self::reserve_symtab_strtab`]. + pub fn reserve_symbol_index(&mut self) -> u32 { + debug_assert_eq!(self.symtab_offset, 0); + let index = self.symtab_num; + self.symtab_num += 1; + index + } + + /// Reserve a number of symbol table entries. + pub fn reserve_symbol_indices(&mut self, count: u32) { + debug_assert_eq!(self.symtab_offset, 0); + self.symtab_num += count; + } + + /// Write a symbol table entry. + pub fn write_symbol(&mut self, symbol: Symbol) { + let mut coff_symbol = pe::ImageSymbol { + name: [0; 8], + value: U32Bytes::new(LE, symbol.value), + section_number: U16Bytes::new(LE, symbol.section_number), + typ: U16Bytes::new(LE, symbol.typ), + storage_class: symbol.storage_class, + number_of_aux_symbols: symbol.number_of_aux_symbols, + }; + match symbol.name { + Name::Short(name) => coff_symbol.name = name, + Name::Long(str_id) => { + let str_offset = self.strtab.get_offset(str_id); + coff_symbol.name[4..8].copy_from_slice(&u32::to_le_bytes(str_offset as u32)); + } + } + self.buffer.write(&coff_symbol); + } + + /// Reserve auxiliary symbols for a file name. + /// + /// Returns the number of auxiliary symbols required. + /// + /// This must be called before [`Self::reserve_symtab_strtab`]. + pub fn reserve_aux_file_name(&mut self, name: &[u8]) -> u8 { + debug_assert_eq!(self.symtab_offset, 0); + let aux_count = (name.len() + pe::IMAGE_SIZEOF_SYMBOL - 1) / pe::IMAGE_SIZEOF_SYMBOL; + self.symtab_num += aux_count as u32; + aux_count as u8 + } + + /// Write auxiliary symbols for a file name. + pub fn write_aux_file_name(&mut self, name: &[u8], aux_count: u8) { + let aux_len = aux_count as usize * pe::IMAGE_SIZEOF_SYMBOL; + debug_assert!(aux_len >= name.len()); + let old_len = self.buffer.len(); + self.buffer.write_bytes(name); + self.buffer.resize(old_len + aux_len); + } + + /// Reserve an auxiliary symbol for a section. + /// + /// Returns the number of auxiliary symbols required. + /// + /// This must be called before [`Self::reserve_symtab_strtab`]. + pub fn reserve_aux_section(&mut self) -> u8 { + debug_assert_eq!(self.symtab_offset, 0); + self.symtab_num += 1; + 1 + } + + /// Write an auxiliary symbol for a section. + pub fn write_aux_section(&mut self, section: AuxSymbolSection) { + let aux = pe::ImageAuxSymbolSection { + length: U32Bytes::new(LE, section.length), + number_of_relocations: if section.number_of_relocations > 0xffff { + U16Bytes::new(LE, 0xffff) + } else { + U16Bytes::new(LE, section.number_of_relocations as u16) + }, + number_of_linenumbers: U16Bytes::new(LE, section.number_of_linenumbers), + check_sum: U32Bytes::new(LE, section.check_sum), + number: U16Bytes::new(LE, section.number as u16), + selection: section.selection, + reserved: 0, + high_number: U16Bytes::new(LE, (section.number >> 16) as u16), + }; + self.buffer.write(&aux); + } + + /// Return the number of reserved symbol table entries. + pub fn symbol_count(&self) -> u32 { + self.symtab_num + } + + /// Add a string to the string table. + /// + /// This must be called before [`Self::reserve_symtab_strtab`]. + pub fn add_string(&mut self, name: &'a [u8]) -> StringId { + debug_assert_eq!(self.strtab_offset, 0); + self.strtab.add(name) + } + + /// Add a section or symbol name to the string table if required. + /// + /// This must be called before [`Self::reserve_symtab_strtab`]. + pub fn add_name(&mut self, name: &'a [u8]) -> Name { + if name.len() > 8 { + Name::Long(self.add_string(name)) + } else { + let mut short_name = [0; 8]; + short_name[..name.len()].copy_from_slice(name); + Name::Short(short_name) + } + } + + /// Reserve the range for the symbol table and string table. + /// + /// This must be called after functions that reserve symbol + /// indices or add strings. + pub fn reserve_symtab_strtab(&mut self) { + debug_assert_eq!(self.symtab_offset, 0); + self.symtab_offset = self.reserve(self.symtab_num as usize * pe::IMAGE_SIZEOF_SYMBOL, 1); + + debug_assert_eq!(self.strtab_offset, 0); + // First 4 bytes of strtab are the length. + self.strtab.write(4, &mut self.strtab_data); + self.strtab_len = self.strtab_data.len() + 4; + self.strtab_offset = self.reserve(self.strtab_len, 1); + } + + /// Write the string table. + pub fn write_strtab(&mut self) { + debug_assert_eq!(self.strtab_offset, self.buffer.len() as u32); + self.buffer + .write_bytes(&u32::to_le_bytes(self.strtab_len as u32)); + self.buffer.write_bytes(&self.strtab_data); + } +} + +/// Shortened and native endian version of [`pe::ImageFileHeader`]. +#[allow(missing_docs)] +#[derive(Debug, Default, Clone)] +pub struct FileHeader { + pub machine: u16, + pub time_date_stamp: u32, + pub characteristics: u16, +} + +/// A section or symbol name. +#[derive(Debug, Clone, Copy)] +pub enum Name { + /// An inline name. + Short([u8; 8]), + /// An id of a string table entry. + Long(StringId), +} + +impl Default for Name { + fn default() -> Name { + Name::Short([0; 8]) + } +} + +// From isn't useful. +#[allow(clippy::from_over_into)] +impl<'a> Into<Name> for &'a [u8; 8] { + fn into(self) -> Name { + Name::Short(*self) + } +} + +/// Native endian version of [`pe::ImageSectionHeader`]. +#[allow(missing_docs)] +#[derive(Debug, Default, Clone)] +pub struct SectionHeader { + pub name: Name, + pub size_of_raw_data: u32, + pub pointer_to_raw_data: u32, + pub pointer_to_relocations: u32, + pub pointer_to_linenumbers: u32, + /// This will automatically be clamped if there are more than 0xffff. + pub number_of_relocations: u32, + pub number_of_linenumbers: u16, + pub characteristics: u32, +} + +/// Native endian version of [`pe::ImageSymbol`]. +#[allow(missing_docs)] +#[derive(Debug, Default, Clone)] +pub struct Symbol { + pub name: Name, + pub value: u32, + pub section_number: u16, + pub typ: u16, + pub storage_class: u8, + pub number_of_aux_symbols: u8, +} + +/// Native endian version of [`pe::ImageAuxSymbolSection`]. +#[allow(missing_docs)] +#[derive(Debug, Default, Clone)] +pub struct AuxSymbolSection { + pub length: u32, + /// This will automatically be clamped if there are more than 0xffff. + pub number_of_relocations: u32, + pub number_of_linenumbers: u16, + pub check_sum: u32, + pub number: u32, + pub selection: u8, +} + +/// Native endian version of [`pe::ImageRelocation`]. +#[allow(missing_docs)] +#[derive(Debug, Default, Clone)] +pub struct Relocation { + pub virtual_address: u32, + pub symbol: u32, + pub typ: u16, +} |