backtrace 0.3.48

use super::{Mapping, Path, Vec};
use object::read::elf::{FileHeader, SectionHeader, SectionTable, Sym};
use object::read::StringTable;
use object::{Bytes, NativeEndian};

#[cfg(target_pointer_width = "32")]
type Elf = object::elf::FileHeader32<NativeEndian>;
#[cfg(target_pointer_width = "64")]
type Elf = object::elf::FileHeader64<NativeEndian>;

impl Mapping {
    pub fn new(path: &Path) -> Option<Mapping> {
        let map = super::mmap(path)?;
        let cx = super::cx(Object::parse(&map)?)?;
        Some(mk!(Mapping { map, cx }))
    }
}

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: Bytes<'a>,
    sections: SectionTable<'a, Elf>,
    strings: StringTable<'a>,
    /// List of pre-parsed and sorted symbols by base address.
    syms: Vec<ParsedSym>,
}

impl<'a> Object<'a> {
    fn parse(data: &'a [u8]) -> Option<Object<'a>> {
        let data = object::Bytes(data);
        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::<Vec<_>>();
        syms.sort_unstable_by_key(|s| s.address);
        Some(Object {
            endian,
            data,
            sections,
            strings,
            syms,
        })
    }

    pub fn section(&self, name: &str) -> Option<&'a [u8]> {
        Some(
            self.sections
                .section_by_name(self.endian, name.as_bytes())?
                .1
                .data(self.endian, self.data)
                .ok()?
                .0,
        )
    }

    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
        }
    }
}