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use std::fmt; use symbolic_common::{Arch, AsSelf, DebugId, Language, Name}; use crate::error::{SymCacheError, SymCacheErrorKind}; use crate::format; /// A platform independent symbolication cache. /// /// Use [`SymCacheWriter`] writer to create SymCaches, including the conversion from object files. /// /// [`SymCacheWriter`]: struct.SymCacheWriter.html pub struct SymCache<'a> { header: format::Header, data: &'a [u8], } impl<'a> SymCache<'a> { /// Parses a SymCache from a binary buffer. pub fn parse(mut data: &'a [u8]) -> Result<Self, SymCacheError> { let header = format::Header::parse(data)?; // The first version of SymCaches used to store offsets relative to the end of the header. This // was corrected in version 2 to store file-absolute offsets. if header.preamble.version == 1 { let offset = std::mem::size_of::<format::HeaderV1>(); if data.len() > offset { data = &data[offset..]; } else { data = &[]; } } Ok(SymCache { header, data }) } /// The version of the SymCache file format. pub fn version(&self) -> u32 { self.header.preamble.version } /// The architecture of the symbol file. pub fn arch(&self) -> Arch { Arch::from_u32(self.header.arch) } /// The debuig identifier of the cache file. pub fn debug_id(&self) -> DebugId { self.header.debug_id } /// Returns true if line information is included. pub fn has_line_info(&self) -> bool { self.header.has_line_records != 0 } /// Returns true if file information is included. pub fn has_file_info(&self) -> bool { // See the writers: if there is file information, there are also lines. self.has_line_info() } /// Returns an iterator over all functions. pub fn functions(&self) -> Functions<'a> { Functions { functions: self.header.functions, symbols: self.header.symbols, files: self.header.files, data: self.data, index: 0, } } /// Given an address this looks up the symbol at that point. /// /// Because of inling information this returns a vector of zero or /// more symbols. If nothing is found then the return value will be /// an empty vector. pub fn lookup(&self, addr: u64) -> Result<Lookup<'a, '_>, SymCacheError> { let funcs = self.function_records()?; // Functions in the function segment are ordered by start address // primarily and by depth secondarily. As a result we want to have // a secondary comparison by the item index. let mut current_id = match funcs.binary_search_by_key(&addr, format::FuncRecord::addr_start) { Ok(index) => index, Err(0) => return Ok(Lookup::empty(self)), Err(next) => next - 1, }; // Seek forward to the deepest inlined function at the same address. while let Some(current_fn) = funcs.get(current_id + 1) { if current_fn.addr_start() != funcs[current_id].addr_start() { break; } current_id += 1; } // Find the function with the line record closest to the address. There are multiple ways // this lookup can go: // a. The current function referred to by `current_id` contains the line record responsible // for the address. However, line records only store the beginning and not the end of // their range, so we need to check for case (d). // b. The current function is top-level ends before the search address. This can happen due // to incomplete debug information or padding sections in the code. There is no match // for this case. // c. Same as 2, but for inline functions. Even though the inlinee doesn't match, one of // its ancestors might still cover with its range. They have to be checked until one // covers the range. Still, case (d) can apply additionally. // d. Even though a function covers the search address, it might be interleaved with // another function that started earlier but contains a line record closer to the search // address. See below for the lookup strategy. let mut closest = None; // Since functions with overlapping ranges can exist, we need to check multiple functions // until we hit a point where we believe no more functions can overlap. Theoretically, this // is the very start of the list. FOR PERFORMANCE REASONS, THIS IMPLEMENATION ONLY CHECKS // FOR OVERLAPS IN INLINE FUNCTIONS. let mut last_id = current_id; loop { let current_fn = &funcs[current_id]; // If the current function covers the address, resolve the closest line record before // the search address. If it is closer than what we've seen before, this is a better // candidate, otherwise we can discard this function. if current_fn.addr_in_range(addr) { let current_addr = self .run_to_line(current_fn, addr)? // A lookup of `None` indicates that there was no line record at all, so just // assume the function's start address as start of the line. .map_or(current_fn.addr_start(), |(line_addr, _, _)| line_addr); if closest.map_or(true, |(_, _, a)| current_addr > a) { closest = Some((current_id, current_fn, current_addr)); } } // We are currently looking at an inline function. Since we're scanning linearly, ensure // that we're also including its parent. This might be from a completely different // inlining branch, so honor the existing `last_id` value as it might be lower. if let Some(parent_id) = current_fn.parent(current_id) { last_id = parent_id.min(last_id); } // We've checked the last function (inclusive), so bail out. if current_id == 0 || current_id == last_id { break; } // Continue with the immediate predecessor. This is not necessarily the inlining parent, // it might be a completely unrelated function from a different branch. Still, it might // cover the search address, so we cannot jump to the parent directly. current_id -= 1; } let (closest_id, closest_fn) = match closest { Some((closest_id, closest_fn, _)) => (closest_id, closest_fn), None => return Ok(Lookup::empty(self)), }; Ok(Lookup { cache: self, funcs, current: Some((addr, closest_id, closest_fn)), inner: None, }) } /// Resolves the raw list of `FuncRecords` from the funcs segment. fn function_records(&self) -> Result<&'a [format::FuncRecord], SymCacheError> { self.header.functions.read(self.data) } /// Locates the source line record for an instruction address within a function. /// /// This function runs through all line records of the given function and /// returns the line closest to the specified instruction. `addr` must be /// within the function range, otherwise the response is implementation /// defined. However, `addr` may point to any address within an instruction. /// /// Returns some tuple containing: /// - `.0`: First instruction address of the source line /// - `.1`: File id of the source file containing this line /// - `.2`: Line number in the file /// /// Returns `None` if the function does not have line records. fn run_to_line( &self, fun: &format::FuncRecord, addr: u64, ) -> Result<Option<(u64, u16, u32)>, SymCacheError> { let records = fun.line_records.read(self.data)?; if records.is_empty() { // A non-empty function without line records can happen in a couple // of cases: // 1. There was no line information present while generating the // symcache. This could be due to unsupported debug symbols or // because they were stripped during the build process. // 2. The symbol was not pulled from debug info but a symbol table. // such function records will generally have an estimated "size" // but never line records. // 3. The body of this function consists of only inlined function // calls. The actual line records of the address range will be // found in the inlined `FuncRecord`s. The `SymCacheWriter` will // try to emit synthetic line records in this case, but they // will be missing if there is not enough debug information. return Ok(None); } // Because of how we determine the outer address on expanding // inlines the first address might actually already be missing // the record. Because of that we pick in any case the first // record as fallback. let mut file_id = records[0].file_id; let mut line = u32::from(records[0].line); let mut running_addr = fun.addr_start(); let mut line_addr = running_addr; for rec in records { // Keep running until we exceed the search address running_addr += u64::from(rec.addr_off); if running_addr > addr { break; } // Remember the starting address of the current line. There might be // multiple line records for a single line if `addr_off` overflows. // So only update `line_addr` if we actually hit a new line. if u32::from(rec.line) != line { line_addr = running_addr; } line = u32::from(rec.line); file_id = rec.file_id; } Ok(Some((line_addr, file_id, line))) } /// Extracts source line information for an instruction address within the /// given `FuncRecord`. /// /// For parents of inlined frames, pass `Some(inner)` to `inner_sym`; /// otherwise None. /// /// This function tries to resolve the source file and line in which the /// corresponding instruction was defined and resolves the full path and /// file name. /// /// The location is first searched within the line records of this function. /// If the function has no own instructions (e.g. due to complete inlining), /// this information is taken from `inner_sym`. If that fails, the file and /// line information will be empty (0 or ""). fn build_line_info( &self, fun: &'a format::FuncRecord, addr: u64, inner_sym: Option<(u32, u64, &'a str, &'a str)>, ) -> Result<LineInfo<'a>, SymCacheError> { let (line, line_addr, filename, base_dir) = if let Some((line_addr, file_id, line)) = self.run_to_line(fun, addr)? { // A missing file record indicates a bad symcache. let file_record = read_file_record(self.data, self.header.files, file_id)? .ok_or_else(|| SymCacheErrorKind::BadCacheFile)?; // The address was found in the function's line records, so use // it directly. This should is the default case for all valid // debugging information and the majority of all frames. ( line, line_addr, file_record.filename.read_str(self.data)?, file_record.base_dir.read_str(self.data)?, ) } else if let Some(inner_sym) = inner_sym { // The source line was not declared in this function. This // happens, if the function body consists of a single inlined // function call. Usually, the `SymCacheWriter` should emit a // synthetic line record in this case; but if debug symbols did // not provide sufficient information, we will still hit this // case. Use the inlined frame's source location as a // replacement to point somewhere useful. inner_sym } else { // We were unable to find any source code. This can happen for // synthetic functions, such as Swift method thunks. In that // case, we can only return empty line information. Also top- // level functions without line records pulled from the symbol // table will hit this branch. (0, 0, "", "") }; Ok(LineInfo { arch: self.arch(), debug_id: self.debug_id(), sym_addr: fun.addr_start(), line_addr, instr_addr: addr, line, lang: Language::from_u32(fun.lang.into()), symbol: read_symbol(self.data, self.header.symbols, fun.symbol_id())?, filename, base_dir, comp_dir: fun.comp_dir.read_str(self.data)?, }) } } impl<'slf, 'd: 'slf> AsSelf<'slf> for SymCache<'d> { type Ref = SymCache<'slf>; fn as_self(&'slf self) -> &Self::Ref { self } } impl fmt::Debug for SymCache<'_> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_struct("SymCache") .field("debug_id", &self.debug_id()) .field("arch", &self.arch()) .field("has_line_info", &self.has_line_info()) .field("has_file_info", &self.has_file_info()) .field("functions", &self.function_records().unwrap_or(&[]).len()) .finish() } } /// An iterator over line matches for an address lookup. #[derive(Clone)] pub struct Lookup<'a, 'c> { cache: &'c SymCache<'a>, funcs: &'a [format::FuncRecord], current: Option<(u64, usize, &'a format::FuncRecord)>, inner: Option<(u32, u64, &'a str, &'a str)>, } impl<'a, 'c> Lookup<'a, 'c> { fn empty(cache: &'c SymCache<'a>) -> Self { Lookup { cache, funcs: &[], current: None, inner: None, } } /// Collects all line matches into a collection. pub fn collect<B>(self) -> Result<B, SymCacheError> where B: std::iter::FromIterator<LineInfo<'a>>, { Iterator::collect(self) } } impl<'a, 'c> Iterator for Lookup<'a, 'c> { type Item = Result<LineInfo<'a>, SymCacheError>; fn next(&mut self) -> Option<Self::Item> { let (addr, id, fun) = self.current?; let line_result = self.cache.build_line_info(fun, addr, None); self.current = fun .parent(id) .map(|parent_id| (fun.addr_start(), parent_id, &self.funcs[parent_id])); if let Ok(ref line_info) = line_result { self.inner = Some(( line_info.line(), line_info.line_address(), line_info.filename(), line_info.compilation_dir(), )); } Some(line_result) } } impl fmt::Debug for Lookup<'_, '_> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { let mut list = f.debug_list(); for line in self.clone() { match line { Ok(line) => { list.entry(&line); } Err(error) => { return error.fmt(f); } } } list.finish() } } /// Information on a matched source line. #[derive(Clone, Debug, Eq, PartialEq)] pub struct LineInfo<'a> { arch: Arch, debug_id: DebugId, sym_addr: u64, line_addr: u64, instr_addr: u64, line: u32, lang: Language, symbol: Option<&'a str>, filename: &'a str, base_dir: &'a str, comp_dir: &'a str, } impl<'a> LineInfo<'a> { /// Architecture of the image referenced by this line. pub fn arch(&self) -> Arch { self.arch } /// Debug identifier of the image referenced by this line. pub fn debug_id(&self) -> DebugId { self.debug_id } /// The instruction address where the enclosing function starts. pub fn function_address(&self) -> u64 { self.sym_addr } /// The instruction address where the line starts. pub fn line_address(&self) -> u64 { self.line_addr } /// The actual instruction address. pub fn instruction_address(&self) -> u64 { self.instr_addr } /// The compilation directory of the function. pub fn compilation_dir(&self) -> &'a str { self.comp_dir } /// The base dir of the current line. pub fn base_dir(&self) -> &str { self.base_dir } /// The filename of the current line. pub fn filename(&self) -> &'a str { self.filename } /// The fully joined path and file name. pub fn path(&self) -> String { symbolic_common::join_path(self.base_dir, self.filename) } /// The line number within the file. pub fn line(&self) -> u32 { self.line } /// The source code language. pub fn language(&self) -> Language { self.lang } /// The string value of the symbol (mangled). pub fn symbol(&self) -> &'a str { self.symbol.unwrap_or("?") } /// The name of the function suitable for demangling. /// /// Use `symbolic::demangle` for demangling this symbol. pub fn function_name(&self) -> Name { Name::with_language(self.symbol(), self.language()) } } impl fmt::Display for LineInfo<'_> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "{}", self.function_name())?; if f.alternate() { let path = self.path(); let line = self.line(); let lang = self.language(); if path != "" || line != 0 || lang != Language::Unknown { write!(f, "\n ")?; if path != "" { write!(f, " at {}", path)?; } if line != 0 { write!(f, " line {}", line)?; } if lang != Language::Unknown { write!(f, " lang {}", lang)?; } } } Ok(()) } } /// An iterator over all functions in a `SymCache`. #[derive(Clone, Debug)] pub struct Functions<'a> { functions: format::Seg<format::FuncRecord>, symbols: format::Seg<format::Seg<u8, u16>>, files: format::Seg<format::FileRecord, u16>, data: &'a [u8], index: u32, } impl<'a> Iterator for Functions<'a> { type Item = Result<Function<'a>, SymCacheError>; fn next(&mut self) -> Option<Self::Item> { let record = match self.functions.get(self.data, self.index) { Ok(Some(record)) => record, Ok(None) => return None, Err(error) => return Some(Err(error)), }; let function = Some(Ok(Function { record, symbols: self.symbols, files: self.files, data: self.data, index: self.index, })); self.index += 1; function } } /// A function in a `SymCache`. /// /// This can be an actual function, an inlined function, or a public symbol. #[derive(Clone)] pub struct Function<'a> { record: &'a format::FuncRecord, symbols: format::Seg<format::Seg<u8, u16>>, files: format::Seg<format::FileRecord, u16>, data: &'a [u8], index: u32, } impl<'a> Function<'a> { /// The ID of the function. pub fn id(&self) -> usize { self.index as usize } /// The ID of the parent function, if this function was inlined. pub fn parent_id(&self) -> Option<usize> { self.record.parent(self.id()) } /// The address where the function starts. pub fn address(&self) -> u64 { self.record.addr_start() } /// The raw name of the function. pub fn symbol(&self) -> &'a str { read_symbol(self.data, self.symbols, self.record.symbol_id()) .unwrap_or(None) .unwrap_or("?") } /// The language of the function. pub fn language(&self) -> Language { Language::from_u32(self.record.lang.into()) } /// The name of the function suitable for demangling. /// /// Use `symbolic::demangle` for demangling this symbol. pub fn name(&self) -> Name { Name::with_language(self.symbol(), self.language()) } /// The compilation dir of the function. pub fn compilation_dir(&self) -> &str { self.record.comp_dir.read_str(self.data).unwrap_or("") } /// An iterator over all lines in the function. pub fn lines(&self) -> Lines<'a> { Lines { lines: self.record.line_records, files: self.files, data: self.data, address: 0, index: 0, } } } /// Helper for printing a human-readable debug representation of line records. struct LinesDebug<'a>(Lines<'a>); impl fmt::Debug for LinesDebug<'_> { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { let mut list = f.debug_list(); for line in self.0.clone() { match line { Ok(line) => { list.entry(&line); } Err(error) => { return error.fmt(f); } } } list.finish() } } impl fmt::Debug for Function<'_> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_struct("Function") .field("id", &self.id()) .field("parent_id", &self.parent_id()) .field("symbol", &self.symbol()) .field("address", &self.address()) .field("compilation_dir", &self.compilation_dir()) .field("language", &self.language()) .field("lines", &LinesDebug(self.lines())) .finish() } } /// An iterator over lines of a SymCache function. #[derive(Clone)] pub struct Lines<'a> { lines: format::Seg<format::LineRecord, u16>, files: format::Seg<format::FileRecord, u16>, data: &'a [u8], address: u64, index: u16, } impl<'a> Iterator for Lines<'a> { type Item = Result<Line<'a>, SymCacheError>; fn next(&mut self) -> Option<Self::Item> { let record = match self.lines.get(self.data, self.index) { Ok(Some(record)) => record, Ok(None) => return None, Err(error) => return Some(Err(error)), }; self.address += u64::from(record.addr_off); self.index += 1; Some(Ok(Line { record, file: read_file_record(self.data, self.files, record.file_id).unwrap_or(None), address: self.address, data: self.data, })) } } /// A line covered by a [`Function`](struct.Function.html). pub struct Line<'a> { record: &'a format::LineRecord, file: Option<&'a format::FileRecord>, data: &'a [u8], address: u64, } impl<'a> Line<'a> { /// The address of the line. pub fn address(&self) -> u64 { self.address } /// The line number of the line. pub fn line(&self) -> u16 { self.record.line } /// The base_dir of the line. pub fn base_dir(&self) -> &str { match self.file { Some(ref record) => record.base_dir.read_str(self.data).unwrap_or(""), None => "", } } /// The filename of the line. pub fn filename(&self) -> &'a str { match self.file { Some(ref record) => record.filename.read_str(self.data).unwrap_or(""), None => "", } } } impl fmt::Debug for Line<'_> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_struct("Line") .field("address", &self.address()) .field("line", &self.line()) .field("base_dir", &self.base_dir()) .field("filename", &self.filename()) .finish() } } /// Look up a single symbol. fn read_symbol( data: &[u8], symbols: format::Seg<format::Seg<u8, u16>>, index: u32, ) -> Result<Option<&str>, SymCacheError> { if index == !0 { Ok(None) } else if let Some(symbol) = symbols.get(data, index)? { symbol.read_str(data).map(Some) } else { Ok(None) } } /// Look up a file record. fn read_file_record( data: &[u8], files: format::Seg<format::FileRecord, u16>, index: u16, ) -> Result<Option<&format::FileRecord>, SymCacheError> { if index == !0 { Ok(None) } else { files.get(data, index) } }