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use crate::Elf;
use crate::ElfError;
use core::str;
use scroll_derive::Pread;
use bit_field::BitField;
#[derive(PartialEq, Eq)]
pub enum SectionType {
/// The first section in a valid ELF's section table will be a null section. It does not detail
/// a real section.
Null,
/// Contains information defined by the program.
ProgBits,
/// Contains a symbol table.
SymTab,
/// Contains a string table.
StrTab,
/// Contains "Rela"-type relocations.
Rela,
/// Contains a symbol hash table.
Hash,
/// Contains tables used during dynamic linking.
Dynamic,
/// Contains note information.
Note,
/// Defines a section as containing uninitialized space. This section does not take up any
/// space in the file and is usually loaded with `0`s during program loading.
NoBits,
/// Contains "Rel"-type relocations.
Rel,
/// Reserved by the spec.
ShLib,
/// Contains a dynamic loader symbol table.
DynSym,
/// A section with type `0x60000000` through `0x6fffffff` inclusive is defined to be
/// environment-specific.
Os(u32),
/// A section with type `0x70000000` through `0x7fffffff` inclusive is defined to be
/// processor-specific.
Proc(u32),
}
#[derive(Debug, Pread)]
#[repr(C)]
pub struct SectionHeader {
pub name: u32,
pub section_type: u32,
pub flags: u64,
pub address: u64,
pub offset: u64,
pub size: u64,
/// Some sections are 'linked' to another section. This field contains the index of the linked
/// section.
pub link: u32,
/// Can contain extra information about a section.
pub info: u32,
pub alignment: u64,
/// If this section contains a table, this is the size of one entry
pub entry_size: u64,
}
impl SectionHeader {
pub(crate) fn validate(&self) -> Result<(), ElfError> {
match self.section_type {
0..=11 | 0x60000000..=0x7fffffff => Ok(()),
_ => Err(ElfError::SectionInvalidType),
}?;
Ok(())
}
pub fn section_type(&self) -> SectionType {
match self.section_type {
0 => SectionType::Null,
1 => SectionType::ProgBits,
2 => SectionType::SymTab,
3 => SectionType::StrTab,
4 => SectionType::Rela,
5 => SectionType::Hash,
6 => SectionType::Dynamic,
7 => SectionType::Note,
8 => SectionType::NoBits,
9 => SectionType::Rel,
10 => SectionType::ShLib,
11 => SectionType::DynSym,
0x60000000..=0x6fffffff => SectionType::Os(self.section_type),
0x70000000..=0x7fffffff => SectionType::Proc(self.section_type),
_ => panic!("section_type called on section with invalid type. Was validate called?"),
}
}
pub fn name<'a>(&self, elf: &'a Elf) -> Option<&'a str> {
if self.name == 0 {
return None;
}
let string_table = elf.sections().nth(elf.header.string_table_index as usize)?;
crate::from_utf8_null_terminated(&string_table.data(elf)?[(self.name as usize)..]).ok()
}
/// Get this section's data, as a byte slice. Returns `None` if the image isn't represented in
/// the file (for example, `NoBits` sections don't have any data).
pub fn data<'a>(&self, elf: &'a Elf) -> Option<&'a [u8]> {
match self.section_type() {
SectionType::Null | SectionType::NoBits => return None,
_ => (),
}
Some(&elf.bytes[(self.offset as usize)..((self.offset + self.size) as usize)])
}
/// Whether this section contains writable data
pub fn is_writable(&self) -> bool {
self.flags.get_bit(0)
}
/// Whether this section should be allocated into the memory image of the program
pub fn is_allocated(&self) -> bool {
self.flags.get_bit(1)
}
/// Whether this section contains executable instructions
pub fn is_executable(&self) -> bool {
self.flags.get_bit(2)
}
}