From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:02:58 +0200 Subject: Adding upstream version 1.64.0+dfsg1. Signed-off-by: Daniel Baumann --- library/backtrace/src/symbolize/gimli/elf.rs | 423 +++++++++++++++++++++++++++ 1 file changed, 423 insertions(+) create mode 100644 library/backtrace/src/symbolize/gimli/elf.rs (limited to 'library/backtrace/src/symbolize/gimli/elf.rs') diff --git a/library/backtrace/src/symbolize/gimli/elf.rs b/library/backtrace/src/symbolize/gimli/elf.rs new file mode 100644 index 000000000..bc71ee2c9 --- /dev/null +++ b/library/backtrace/src/symbolize/gimli/elf.rs @@ -0,0 +1,423 @@ +use super::mystd::ffi::{OsStr, OsString}; +use super::mystd::fs; +use super::mystd::os::unix::ffi::{OsStrExt, OsStringExt}; +use super::mystd::path::{Path, PathBuf}; +use super::Either; +use super::{Context, Mapping, Stash, Vec}; +use core::convert::{TryFrom, TryInto}; +use core::str; +use object::elf::{ELFCOMPRESS_ZLIB, ELF_NOTE_GNU, NT_GNU_BUILD_ID, SHF_COMPRESSED}; +use object::read::elf::{CompressionHeader, FileHeader, SectionHeader, SectionTable, Sym}; +use object::read::StringTable; +use object::{BigEndian, Bytes, NativeEndian}; + +#[cfg(target_pointer_width = "32")] +type Elf = object::elf::FileHeader32; +#[cfg(target_pointer_width = "64")] +type Elf = object::elf::FileHeader64; + +impl Mapping { + pub fn new(path: &Path) -> Option { + let map = super::mmap(path)?; + Mapping::mk_or_other(map, |map, stash| { + let object = Object::parse(&map)?; + + // Try to locate an external debug file using the build ID. + if let Some(path_debug) = object.build_id().and_then(locate_build_id) { + if let Some(mapping) = Mapping::new_debug(path_debug, None) { + return Some(Either::A(mapping)); + } + } + + // Try to locate an external debug file using the GNU debug link section. + if let Some((path_debug, crc)) = object.gnu_debuglink_path(path) { + if let Some(mapping) = Mapping::new_debug(path_debug, Some(crc)) { + return Some(Either::A(mapping)); + } + } + + Context::new(stash, object, None).map(Either::B) + }) + } + + /// Load debuginfo from an external debug file. + fn new_debug(path: PathBuf, crc: Option) -> Option { + let map = super::mmap(&path)?; + Mapping::mk(map, |map, stash| { + let object = Object::parse(&map)?; + + if let Some(_crc) = crc { + // TODO: check crc + } + + // Try to locate a supplementary object file. + if let Some((path_sup, build_id_sup)) = object.gnu_debugaltlink_path(&path) { + if let Some(map_sup) = super::mmap(&path_sup) { + let map_sup = stash.set_mmap_aux(map_sup); + if let Some(sup) = Object::parse(map_sup) { + if sup.build_id() == Some(build_id_sup) { + return Context::new(stash, object, Some(sup)); + } + } + } + } + + Context::new(stash, object, None) + }) + } +} + +struct ParsedSym { + address: u64, + size: u64, + name: u32, +} + +pub struct Object<'a> { + /// Zero-sized type representing the native endianness. + /// + /// We could use a literal instead, but this helps ensure correctness. + endian: NativeEndian, + /// The entire file data. + data: &'a [u8], + sections: SectionTable<'a, Elf>, + strings: StringTable<'a>, + /// List of pre-parsed and sorted symbols by base address. + syms: Vec, +} + +impl<'a> Object<'a> { + fn parse(data: &'a [u8]) -> Option> { + let elf = Elf::parse(data).ok()?; + let endian = elf.endian().ok()?; + let sections = elf.sections(endian, data).ok()?; + let mut syms = sections + .symbols(endian, data, object::elf::SHT_SYMTAB) + .ok()?; + if syms.is_empty() { + syms = sections + .symbols(endian, data, object::elf::SHT_DYNSYM) + .ok()?; + } + let strings = syms.strings(); + + let mut syms = syms + .iter() + // Only look at function/object symbols. This mirrors what + // libbacktrace does and in general we're only symbolicating + // function addresses in theory. Object symbols correspond + // to data, and maybe someone's crazy enough to have a + // function go into static data? + .filter(|sym| { + let st_type = sym.st_type(); + st_type == object::elf::STT_FUNC || st_type == object::elf::STT_OBJECT + }) + // skip anything that's in an undefined section header, + // since it means it's an imported function and we're only + // symbolicating with locally defined functions. + .filter(|sym| sym.st_shndx(endian) != object::elf::SHN_UNDEF) + .map(|sym| { + let address = sym.st_value(endian).into(); + let size = sym.st_size(endian).into(); + let name = sym.st_name(endian); + ParsedSym { + address, + size, + name, + } + }) + .collect::>(); + syms.sort_unstable_by_key(|s| s.address); + Some(Object { + endian, + data, + sections, + strings, + syms, + }) + } + + pub fn section(&self, stash: &'a Stash, name: &str) -> Option<&'a [u8]> { + if let Some(section) = self.section_header(name) { + let mut data = Bytes(section.data(self.endian, self.data).ok()?); + + // Check for DWARF-standard (gABI) compression, i.e., as generated + // by ld's `--compress-debug-sections=zlib-gabi` flag. + let flags: u64 = section.sh_flags(self.endian).into(); + if (flags & u64::from(SHF_COMPRESSED)) == 0 { + // Not compressed. + return Some(data.0); + } + + let header = data.read::<::CompressionHeader>().ok()?; + if header.ch_type(self.endian) != ELFCOMPRESS_ZLIB { + // Zlib compression is the only known type. + return None; + } + let size = usize::try_from(header.ch_size(self.endian)).ok()?; + let buf = stash.allocate(size); + decompress_zlib(data.0, buf)?; + return Some(buf); + } + + // Check for the nonstandard GNU compression format, i.e., as generated + // by ld's `--compress-debug-sections=zlib-gnu` flag. This means that if + // we're actually asking for `.debug_info` then we need to look up a + // section named `.zdebug_info`. + if !name.starts_with(".debug_") { + return None; + } + let debug_name = name[7..].as_bytes(); + let compressed_section = self + .sections + .iter() + .filter_map(|header| { + let name = self.sections.section_name(self.endian, header).ok()?; + if name.starts_with(b".zdebug_") && &name[8..] == debug_name { + Some(header) + } else { + None + } + }) + .next()?; + let mut data = Bytes(compressed_section.data(self.endian, self.data).ok()?); + if data.read_bytes(8).ok()?.0 != b"ZLIB\0\0\0\0" { + return None; + } + let size = usize::try_from(data.read::>().ok()?.get(BigEndian)).ok()?; + let buf = stash.allocate(size); + decompress_zlib(data.0, buf)?; + Some(buf) + } + + fn section_header(&self, name: &str) -> Option<&::SectionHeader> { + self.sections + .section_by_name(self.endian, name.as_bytes()) + .map(|(_index, section)| section) + } + + pub fn search_symtab<'b>(&'b self, addr: u64) -> Option<&'b [u8]> { + // Same sort of binary search as Windows above + let i = match self.syms.binary_search_by_key(&addr, |sym| sym.address) { + Ok(i) => i, + Err(i) => i.checked_sub(1)?, + }; + let sym = self.syms.get(i)?; + if sym.address <= addr && addr <= sym.address + sym.size { + self.strings.get(sym.name).ok() + } else { + None + } + } + + pub(super) fn search_object_map(&self, _addr: u64) -> Option<(&Context<'_>, u64)> { + None + } + + fn build_id(&self) -> Option<&'a [u8]> { + for section in self.sections.iter() { + if let Ok(Some(mut notes)) = section.notes(self.endian, self.data) { + while let Ok(Some(note)) = notes.next() { + if note.name() == ELF_NOTE_GNU && note.n_type(self.endian) == NT_GNU_BUILD_ID { + return Some(note.desc()); + } + } + } + } + None + } + + // The contents of the ".gnu_debuglink" section is documented at: + // https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html + fn gnu_debuglink_path(&self, path: &Path) -> Option<(PathBuf, u32)> { + let section = self.section_header(".gnu_debuglink")?; + let data = section.data(self.endian, self.data).ok()?; + let len = data.iter().position(|x| *x == 0)?; + let filename = &data[..len]; + let offset = (len + 1 + 3) & !3; + let crc_bytes = data + .get(offset..offset + 4) + .and_then(|bytes| bytes.try_into().ok())?; + let crc = u32::from_ne_bytes(crc_bytes); + let path_debug = locate_debuglink(path, filename)?; + Some((path_debug, crc)) + } + + // The format of the ".gnu_debugaltlink" section is based on gdb. + fn gnu_debugaltlink_path(&self, path: &Path) -> Option<(PathBuf, &'a [u8])> { + let section = self.section_header(".gnu_debugaltlink")?; + let data = section.data(self.endian, self.data).ok()?; + let len = data.iter().position(|x| *x == 0)?; + let filename = &data[..len]; + let build_id = &data[len + 1..]; + let path_sup = locate_debugaltlink(path, filename, build_id)?; + Some((path_sup, build_id)) + } +} + +fn decompress_zlib(input: &[u8], output: &mut [u8]) -> Option<()> { + use miniz_oxide::inflate::core::inflate_flags::{ + TINFL_FLAG_PARSE_ZLIB_HEADER, TINFL_FLAG_USING_NON_WRAPPING_OUTPUT_BUF, + }; + use miniz_oxide::inflate::core::{decompress, DecompressorOxide}; + use miniz_oxide::inflate::TINFLStatus; + + let (status, in_read, out_read) = decompress( + &mut DecompressorOxide::new(), + input, + output, + 0, + TINFL_FLAG_USING_NON_WRAPPING_OUTPUT_BUF | TINFL_FLAG_PARSE_ZLIB_HEADER, + ); + if status == TINFLStatus::Done && in_read == input.len() && out_read == output.len() { + Some(()) + } else { + None + } +} + +const DEBUG_PATH: &[u8] = b"/usr/lib/debug"; + +fn debug_path_exists() -> bool { + cfg_if::cfg_if! { + if #[cfg(any(target_os = "freebsd", target_os = "linux"))] { + use core::sync::atomic::{AtomicU8, Ordering}; + static DEBUG_PATH_EXISTS: AtomicU8 = AtomicU8::new(0); + + let mut exists = DEBUG_PATH_EXISTS.load(Ordering::Relaxed); + if exists == 0 { + exists = if Path::new(OsStr::from_bytes(DEBUG_PATH)).is_dir() { + 1 + } else { + 2 + }; + DEBUG_PATH_EXISTS.store(exists, Ordering::Relaxed); + } + exists == 1 + } else { + false + } + } +} + +/// Locate a debug file based on its build ID. +/// +/// The format of build id paths is documented at: +/// https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html +fn locate_build_id(build_id: &[u8]) -> Option { + const BUILD_ID_PATH: &[u8] = b"/usr/lib/debug/.build-id/"; + const BUILD_ID_SUFFIX: &[u8] = b".debug"; + + if build_id.len() < 2 { + return None; + } + + if !debug_path_exists() { + return None; + } + + let mut path = + Vec::with_capacity(BUILD_ID_PATH.len() + BUILD_ID_SUFFIX.len() + build_id.len() * 2 + 1); + path.extend(BUILD_ID_PATH); + path.push(hex(build_id[0] >> 4)); + path.push(hex(build_id[0] & 0xf)); + path.push(b'/'); + for byte in &build_id[1..] { + path.push(hex(byte >> 4)); + path.push(hex(byte & 0xf)); + } + path.extend(BUILD_ID_SUFFIX); + Some(PathBuf::from(OsString::from_vec(path))) +} + +fn hex(byte: u8) -> u8 { + if byte < 10 { + b'0' + byte + } else { + b'a' + byte - 10 + } +} + +/// Locate a file specified in a `.gnu_debuglink` section. +/// +/// `path` is the file containing the section. +/// `filename` is from the contents of the section. +/// +/// Search order is based on gdb, documented at: +/// https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html +/// +/// gdb also allows the user to customize the debug search path, but we don't. +/// +/// gdb also supports debuginfod, but we don't yet. +fn locate_debuglink(path: &Path, filename: &[u8]) -> Option { + let path = fs::canonicalize(path).ok()?; + let parent = path.parent()?; + let mut f = PathBuf::from(OsString::with_capacity( + DEBUG_PATH.len() + parent.as_os_str().len() + filename.len() + 2, + )); + let filename = Path::new(OsStr::from_bytes(filename)); + + // Try "/parent/filename" if it differs from "path" + f.push(parent); + f.push(filename); + if f != path && f.is_file() { + return Some(f); + } + + // Try "/parent/.debug/filename" + let mut s = OsString::from(f); + s.clear(); + f = PathBuf::from(s); + f.push(parent); + f.push(".debug"); + f.push(filename); + if f.is_file() { + return Some(f); + } + + if debug_path_exists() { + // Try "/usr/lib/debug/parent/filename" + let mut s = OsString::from(f); + s.clear(); + f = PathBuf::from(s); + f.push(OsStr::from_bytes(DEBUG_PATH)); + f.push(parent.strip_prefix("/").unwrap()); + f.push(filename); + if f.is_file() { + return Some(f); + } + } + + None +} + +/// Locate a file specified in a `.gnu_debugaltlink` section. +/// +/// `path` is the file containing the section. +/// `filename` and `build_id` are the contents of the section. +/// +/// Search order is based on gdb: +/// - filename, which is either absolute or relative to `path` +/// - the build ID path under `BUILD_ID_PATH` +/// +/// gdb also allows the user to customize the debug search path, but we don't. +/// +/// gdb also supports debuginfod, but we don't yet. +fn locate_debugaltlink(path: &Path, filename: &[u8], build_id: &[u8]) -> Option { + let filename = Path::new(OsStr::from_bytes(filename)); + if filename.is_absolute() { + if filename.is_file() { + return Some(filename.into()); + } + } else { + let path = fs::canonicalize(path).ok()?; + let parent = path.parent()?; + let mut f = PathBuf::from(parent); + f.push(filename); + if f.is_file() { + return Some(f); + } + } + + locate_build_id(build_id) +} -- cgit v1.2.3