1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139


#[derive(Debug)]
#[repr(packed)] // repr(C) would add unwanted padding before first_section
pub struct ElfSectionsTag {
    typ: u32,
    size: u32,
    pub number_of_sections: u32,
    entry_size: u32,
    shndx: u32, // string table
    first_section: ElfSection,
}

impl ElfSectionsTag {
    pub fn sections(&'static self) -> ElfSectionIter {
        ElfSectionIter {
            current_section: &self.first_section,
            remaining_sections: self.number_of_sections - 1,
            entry_size: self.entry_size,
        }
    }

    pub fn string_table(&self) -> &'static StringTable {
        unsafe {
            let string_table_ptr =
                (&self.first_section as *const ElfSection).offset(self.shndx as isize);
            &*((*string_table_ptr).addr as *const StringTable)
        }
    }
}

pub struct StringTable(u8);

impl StringTable {
    pub fn section_name(&self, section: &ElfSection) -> &'static str {
        use core::{str, slice};

        let name_ptr = unsafe {
            (&self.0 as *const u8).offset(section.name_index as isize)
        };
        let strlen = {
            let mut len = 0;
            while unsafe { *name_ptr.offset(len) } != 0 {
                len += 1;
            }
            len as usize
        };

        str::from_utf8( unsafe {
            slice::from_raw_parts(name_ptr, strlen)
        }).unwrap()
    }
}

#[derive(Clone)]
pub struct ElfSectionIter {
    current_section: &'static ElfSection,
    remaining_sections: u32,
    entry_size: u32,
}

impl Iterator for ElfSectionIter {
    type Item = &'static ElfSection;
    fn next(&mut self) -> Option<&'static ElfSection> {
        if self.remaining_sections == 0 {
            None
        } else {
            let section = self.current_section;
            let next_section_addr = (self.current_section as *const _ as u64) + self.entry_size as u64;
            self.current_section = unsafe{ &*(next_section_addr as *const ElfSection) };
            self.remaining_sections -= 1;
            if section.typ == ElfSectionType::Unused as u32 {
                self.next()
            } else {
                Some(section)
            }
        }
    }
}

#[derive(Debug)]
#[repr(C)]
pub struct ElfSection {
    name_index: u32,
    typ: u32,
    pub flags: u64,
    pub addr: u64,
    offset: u64,
    pub size: u64,
    link: u32,
    info: u32,
    addralign: u64,
    entry_size: u64,
}

impl ElfSection {
    pub fn start_address(&self) -> usize {
        self.addr as usize
    }

    pub fn end_address(&self) -> usize {
        (self.addr + self.size) as usize
    }

    pub fn flags(&self) -> ElfSectionFlags {
        ElfSectionFlags::from_bits_truncate(self.flags)
    }

    pub fn is_allocated(&self) -> bool {
        self.flags().contains(ELF_SECTION_ALLOCATED)
    }
}

#[repr(u32)]
pub enum ElfSectionType {
    Unused = 0,
    ProgramSection = 1,
    LinkerSymbolTable = 2,
    StringTable = 3,
    RelaRelocation = 4,
    SymbolHashTable = 5,
    DynamicLinkingTable = 6,
    Note = 7,
    Uninitialized = 8,
    RelRelocation = 9,
    Reserved = 10,
    DynamicLoaderSymbolTable = 11,
    // plus environment-specific use from 0x60000000 to 0x6FFFFFFF
    // plus processor-specific use from 0x70000000 to 0x7FFFFFFF
}

bitflags! {
    flags ElfSectionFlags: u64 {
        const ELF_SECTION_WRITABLE = 0x1,
        const ELF_SECTION_ALLOCATED = 0x2,
        const ELF_SECTION_EXECUTABLE = 0x4,
        // plus environment-specific use at 0x0F000000
        // plus processor-specific use at 0xF0000000
    }
}