# lib.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/xmas-elf-0.7.0/src/lib.rs`.
Keywords: rust, rustlang, rust-lang

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    #![no_std]
    #![warn(box_pointers, missing_copy_implementations, missing_debug_implementations)]
    #![warn(unused_extern_crates, unused_import_braces, unused_qualifications, unused_results)]
    #![warn(variant_size_differences)]

    // TODO move to a module
    macro_rules! check {
        ($e:expr) => {
            if !$e {
                return Err("");
            }
        };
        ($e:expr, $msg: expr) => {
            if !$e {
                return Err($msg);
            }
        };
    }

    #[cfg(feature = "compression")]
    extern crate std;
    #[cfg(feature = "compression")]
    extern crate flate2;

    extern crate zero;

    pub mod header;
    pub mod sections;
    pub mod program;
    pub mod symbol_table;
    pub mod dynamic;
    pub mod hash;

    use header::Header;
    use sections::{SectionHeader, SectionIter};
    use program::{ProgramHeader, ProgramIter};
    use zero::{read, read_str};

    pub type P32 = u32;
    pub type P64 = u64;

    #[derive(Debug)]
    pub struct ElfFile<'a> {
        pub input: &'a [u8],
        pub header: Header<'a>,
    }

    impl<'a> ElfFile<'a> {
        pub fn new(input: &'a [u8]) -> Result<ElfFile<'a>, &'static str> {
            let header = try!(header::parse_header(input));
            Ok(ElfFile {
                input: input,
                header: header,
            })
        }

        pub fn section_header(&self, index: u16) -> Result<SectionHeader<'a>, &'static str> {
            sections::parse_section_header(self.input, self.header, index)
        }

        pub fn section_iter<'b>(&'b self) -> SectionIter<'b, 'a> {
            SectionIter {
                file: self,
                next_index: 0,
            }
        }

        pub fn program_header(&self, index: u16) -> Result<ProgramHeader<'a>, &'static str> {
            program::parse_program_header(self.input, self.header, index)
        }

        pub fn program_iter<'b>(&'b self) -> ProgramIter<'b, 'a> {
            ProgramIter {
                file: self,
                next_index: 0,
            }
        }

        pub fn get_shstr(&self, index: u32) -> Result<&'a str, &'static str> {
            self.get_shstr_table().map(|shstr_table| read_str(&shstr_table[(index as usize)..]))
        }

        pub fn get_string(&self, index: u32) -> Result<&'a str, &'static str> {
            let header = try!(self.find_section_by_name(".strtab").ok_or("no .strtab section"));
            if try!(header.get_type()) != sections::ShType::StrTab {
                return Err("expected .strtab to be StrTab");
            }
            Ok(read_str(&header.raw_data(self)[(index as usize)..]))
        }

        pub fn get_dyn_string(&self, index: u32) -> Result<&'a str, &'static str> {
            let header = try!(self.find_section_by_name(".dynstr").ok_or("no .dynstr section"));
            Ok(read_str(&header.raw_data(self)[(index as usize)..]))
        }

        // This is really, stupidly slow. Not sure how to fix that, perhaps keeping
        // a HashTable mapping names to section header indices?
        pub fn find_section_by_name(&self, name: &str) -> Option<SectionHeader<'a>> {
            for sect in self.section_iter() {
                if let Ok(sect_name) = sect.get_name(self) {
                    if sect_name == name {
                        return Some(sect);
                    }
                }
            }

            None
        }

        fn get_shstr_table(&self) -> Result<&'a [u8], &'static str> {
            // TODO cache this?
            let header = self.section_header(self.header.pt2.sh_str_index());
            header.map(|h| &self.input[(h.offset() as usize)..])
        }
    }

    /// A trait for things that are common ELF conventions but not part of the ELF
    /// specification.
    pub trait Extensions<'a> {
        /// Parse and return the value of the .note.gnu.build-id section, if it
        /// exists and is well-formed.
        fn get_gnu_buildid(&self) -> Option<&'a [u8]>;

        /// Parse and return the value of the .gnu_debuglink section, if it
        /// exists and is well-formed.
        fn get_gnu_debuglink(&self) -> Option<(&'a str, u32)>;
    }

    impl<'a> Extensions<'a> for ElfFile<'a> {
        fn get_gnu_buildid(&self) -> Option<&'a [u8]> {
            self.find_section_by_name(".note.gnu.build-id")
                .and_then(|header| header.get_data(self).ok())
                .and_then(|data| match data {
                    // Handle Note32 if it's ever implemented!
                    sections::SectionData::Note64(header, data) => Some((header, data)),
                    _ => None,
                })
                .and_then(|(header, data)| {
                    // Check for NT_GNU_BUILD_ID
                    if header.type_() != 0x3 {
                        return None;
                    }

                    if header.name(data) != "GNU" {
                        return None;
                    }

                    Some(header.desc(data))
                })
        }

        fn get_gnu_debuglink(&self) -> Option<(&'a str, u32)> {
            self.find_section_by_name(".gnu_debuglink")
                .map(|header| header.raw_data(self))
                .and_then(|data| {
                    let file = read_str(data);
                    // Round up to the nearest multiple of 4.
                    let checksum_pos = ((file.len() + 4) / 4) * 4;
                    let checksum: u32 = *read(&data[checksum_pos..]);
                    Some((file, checksum))
                })
        }
    }

    #[cfg(test)]
    #[macro_use]
    extern crate std;

    #[cfg(test)]
    mod test {
        use std::prelude::v1::*;

        use std::mem;

        use super::*;
        use header::{HeaderPt1, HeaderPt2_};

        fn mk_elf_header(class: u8) -> Vec<u8> {
            let header_size = mem::size_of::<HeaderPt1>() +
                              match class {
                1 => mem::size_of::<HeaderPt2_<P32>>(),
                2 => mem::size_of::<HeaderPt2_<P64>>(),
                _ => 0,
            };
            let mut header = vec![0x7f, 'E' as u8, 'L' as u8, 'F' as u8];
            let data = 1u8;
            let version = 1u8;
            header.extend_from_slice(&[class, data, version]);
            header.resize(header_size, 0);
            header
        }

        #[test]
        fn interpret_class() {
            assert!(ElfFile::new(&mk_elf_header(0)).is_err());
            assert!(ElfFile::new(&mk_elf_header(1)).is_ok());
            assert!(ElfFile::new(&mk_elf_header(2)).is_ok());
            assert!(ElfFile::new(&mk_elf_header(42u8)).is_err());
        }
    }