forked from Bananymous/banan-os
380 lines
8.8 KiB
C++
380 lines
8.8 KiB
C++
#include <BAN/ScopeGuard.h>
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#include <kernel/Process.h>
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#include <LibELF/ELF.h>
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#include <LibELF/Values.h>
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#include <fcntl.h>
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#define ELF_PRINT_HEADERS 0
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namespace LibELF
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{
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BAN::ErrorOr<ELF*> ELF::load_from_file(BAN::StringView file_path)
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{
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ELF* elf = nullptr;
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{
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BAN::Vector<uint8_t> data;
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int fd = TRY(Kernel::Process::current().open(file_path, O_RDONLY));
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BAN::ScopeGuard _([fd] { MUST(Kernel::Process::current().close(fd)); });
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struct stat st;
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TRY(Kernel::Process::current().fstat(fd, &st));
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TRY(data.resize(st.st_size));
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TRY(Kernel::Process::current().read(fd, data.data(), data.size()));
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elf = new ELF(BAN::move(data));
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ASSERT(elf);
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}
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if (auto res = elf->load(); res.is_error())
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{
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delete elf;
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return res.error();
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}
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return elf;
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}
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BAN::ErrorOr<void> ELF::load()
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{
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if (m_data.size() < EI_NIDENT)
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{
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dprintln("Too small ELF file");
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return BAN::Error::from_errno(EINVAL);
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}
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if (m_data[EI_MAG0] != ELFMAG0 ||
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m_data[EI_MAG1] != ELFMAG1 ||
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m_data[EI_MAG2] != ELFMAG2 ||
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m_data[EI_MAG3] != ELFMAG3)
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{
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dprintln("Invalid ELF header");
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return BAN::Error::from_errno(EINVAL);
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}
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if (m_data[EI_DATA] != ELFDATA2LSB)
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{
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dprintln("Only little-endian is supported");
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return BAN::Error::from_errno(EINVAL);
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}
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if (m_data[EI_VERSION] != EV_CURRENT)
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{
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dprintln("Invalid ELF version");
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return BAN::Error::from_errno(EINVAL);
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}
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if (m_data[EI_CLASS] == ELFCLASS64)
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{
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if (m_data.size() <= sizeof(Elf64FileHeader))
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{
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dprintln("Too small ELF file");
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return BAN::Error::from_errno(EINVAL);
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}
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auto& header = file_header64();
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if (!parse_elf64_file_header(header))
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return BAN::Error::from_errno(EINVAL);
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for (size_t i = 0; i < header.e_phnum; i++)
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{
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auto& program_header = program_header64(i);
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if (!parse_elf64_program_header(program_header))
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return BAN::Error::from_errno(EINVAL);
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}
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for (size_t i = 1; i < header.e_shnum; i++)
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{
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auto& section_header = section_header64(i);
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if (!parse_elf64_section_header(section_header))
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return BAN::Error::from_errno(EINVAL);
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}
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}
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else if (m_data[EI_CLASS] == ELFCLASS32)
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{
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if (m_data.size() <= sizeof(Elf32FileHeader))
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{
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dprintln("Too small ELF file");
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return BAN::Error::from_errno(EINVAL);
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}
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auto& header = file_header32();
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if (!parse_elf32_file_header(header))
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return BAN::Error::from_errno(EINVAL);
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for (size_t i = 0; i < header.e_phnum; i++)
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{
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auto& program_header = program_header32(i);
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if (!parse_elf32_program_header(program_header))
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return BAN::Error::from_errno(EINVAL);
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}
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for (size_t i = 1; i < header.e_shnum; i++)
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{
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auto& section_header = section_header32(i);
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if (!parse_elf32_section_header(section_header))
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return BAN::Error::from_errno(EINVAL);
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}
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}
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return {};
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}
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bool ELF::is_x86_32() const { return m_data[EI_CLASS] == ELFCLASS32; }
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bool ELF::is_x86_64() const { return m_data[EI_CLASS] == ELFCLASS64; }
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/*
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64 bit ELF
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*/
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const char* ELF::lookup_section_name64(uint32_t offset) const
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{
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return lookup_string64(file_header64().e_shstrndx, offset);
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}
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const char* ELF::lookup_string64(size_t table_index, uint32_t offset) const
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{
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if (table_index == SHN_UNDEF)
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return nullptr;
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auto& section_header = section_header64(table_index);
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return (const char*)m_data.data() + section_header.sh_offset + offset;
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}
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bool ELF::parse_elf64_file_header(const Elf64FileHeader& header)
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{
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if (header.e_type != ET_EXEC)
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{
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dprintln("Only executable files are supported");
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return false;
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}
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if (header.e_version != EV_CURRENT)
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{
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dprintln("Invalid ELF version");
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return false;
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}
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return true;
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}
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bool ELF::parse_elf64_program_header(const Elf64ProgramHeader& header)
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{
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#if ELF_PRINT_HEADERS
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dprintln("program header");
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dprintln(" type {H}", header.p_type);
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dprintln(" flags {H}", header.p_flags);
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dprintln(" offset {H}", header.p_offset);
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dprintln(" vaddr {H}", header.p_vaddr);
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dprintln(" paddr {H}", header.p_paddr);
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dprintln(" filesz {}", header.p_filesz);
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dprintln(" memsz {}", header.p_memsz);
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dprintln(" align {}", header.p_align);
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#endif
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(void)header;
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return true;
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}
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bool ELF::parse_elf64_section_header(const Elf64SectionHeader& header)
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{
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#if ELF_PRINT_HEADERS
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if (auto* name = lookup_section_name64(header.sh_name))
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dprintln("{}", name);
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switch (header.sh_type)
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{
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case SHT_NULL:
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dprintln(" SHT_NULL");
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break;
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case SHT_PROGBITS:
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dprintln(" SHT_PROGBITS");
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break;
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case SHT_SYMTAB:
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for (size_t i = 1; i < header.sh_size / header.sh_entsize; i++)
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{
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auto& symbol = ((const Elf64Symbol*)(m_data.data() + header.sh_offset))[i];
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if (auto* name = lookup_string64(header.sh_link, symbol.st_name))
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dprintln(" {}", name);
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}
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break;
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case SHT_STRTAB:
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dprintln(" SHT_STRTAB");
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break;
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case SHT_RELA:
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dprintln(" SHT_RELA");
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break;
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case SHT_NOBITS:
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dprintln(" SHT_NOBITS");
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break;
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case SHT_REL:
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dprintln(" SHT_REL");
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break;
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case SHT_SHLIB:
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dprintln(" SHT_SHLIB");
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break;
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case SHT_DYNSYM:
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dprintln(" SHT_DYNSYM");
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break;
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default:
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ASSERT(false);
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}
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#endif
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(void)header;
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return true;
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}
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const Elf64FileHeader& ELF::file_header64() const
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{
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ASSERT(is_x86_64());
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return *(const Elf64FileHeader*)m_data.data();
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}
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const Elf64ProgramHeader& ELF::program_header64(size_t index) const
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{
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ASSERT(is_x86_64());
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const auto& file_header = file_header64();
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ASSERT(index < file_header.e_phnum);
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return *(const Elf64ProgramHeader*)(m_data.data() + file_header.e_phoff + file_header.e_phentsize * index);
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}
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const Elf64SectionHeader& ELF::section_header64(size_t index) const
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{
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ASSERT(is_x86_64());
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const auto& file_header = file_header64();
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ASSERT(index < file_header.e_shnum);
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return *(const Elf64SectionHeader*)(m_data.data() + file_header.e_shoff + file_header.e_shentsize * index);
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}
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/*
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32 bit ELF
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*/
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const char* ELF::lookup_section_name32(uint32_t offset) const
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{
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return lookup_string32(file_header32().e_shstrndx, offset);
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}
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const char* ELF::lookup_string32(size_t table_index, uint32_t offset) const
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{
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if (table_index == SHN_UNDEF)
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return nullptr;
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auto& section_header = section_header32(table_index);
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return (const char*)m_data.data() + section_header.sh_offset + offset;
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}
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bool ELF::parse_elf32_file_header(const Elf32FileHeader& header)
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{
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if (header.e_type != ET_EXEC)
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{
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dprintln("Only executable files are supported");
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return false;
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}
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if (header.e_version != EV_CURRENT)
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{
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dprintln("Invalid ELF version");
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return false;
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}
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return true;
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}
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bool ELF::parse_elf32_program_header(const Elf32ProgramHeader& header)
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{
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#if ELF_PRINT_HEADERS
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dprintln("program header");
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dprintln(" type {H}", header.p_type);
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dprintln(" flags {H}", header.p_flags);
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dprintln(" offset {H}", header.p_offset);
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dprintln(" vaddr {H}", header.p_vaddr);
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dprintln(" paddr {H}", header.p_paddr);
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dprintln(" filesz {}", header.p_filesz);
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dprintln(" memsz {}", header.p_memsz);
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dprintln(" align {}", header.p_align);
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#endif
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(void)header;
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return true;
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}
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bool ELF::parse_elf32_section_header(const Elf32SectionHeader& header)
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{
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#if ELF_PRINT_HEADERS
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if (auto* name = lookup_section_name32(header.sh_name))
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dprintln("{}", name);
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switch (header.sh_type)
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{
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case SHT_NULL:
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dprintln(" SHT_NULL");
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break;
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case SHT_PROGBITS:
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dprintln(" SHT_PROGBITS");
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break;
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case SHT_SYMTAB:
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for (size_t i = 1; i < header.sh_size / header.sh_entsize; i++)
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{
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auto& symbol = ((const Elf32Symbol*)(m_data.data() + header.sh_offset))[i];
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if (auto* name = lookup_string32(header.sh_link, symbol.st_name))
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dprintln(" {}", name);
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}
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break;
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case SHT_STRTAB:
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dprintln(" SHT_STRTAB");
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break;
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case SHT_RELA:
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dprintln(" SHT_RELA");
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break;
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case SHT_NOBITS:
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dprintln(" SHT_NOBITS");
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break;
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case SHT_REL:
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dprintln(" SHT_REL");
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break;
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case SHT_SHLIB:
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dprintln(" SHT_SHLIB");
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break;
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case SHT_DYNSYM:
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dprintln(" SHT_DYNSYM");
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break;
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default:
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ASSERT(false);
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}
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#endif
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(void)header;
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return true;
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}
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const Elf32FileHeader& ELF::file_header32() const
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{
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ASSERT(is_x86_32());
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return *(const Elf32FileHeader*)m_data.data();
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}
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const Elf32ProgramHeader& ELF::program_header32(size_t index) const
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{
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ASSERT(is_x86_32());
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const auto& file_header = file_header32();
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ASSERT(index < file_header.e_phnum);
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return *(const Elf32ProgramHeader*)(m_data.data() + file_header.e_phoff + file_header.e_phentsize * index);
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}
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const Elf32SectionHeader& ELF::section_header32(size_t index) const
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{
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ASSERT(is_x86_32());
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const auto& file_header = file_header32();
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ASSERT(index < file_header.e_shnum);
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return *(const Elf32SectionHeader*)(m_data.data() + file_header.e_shoff + file_header.e_shentsize * index);
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}
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}
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