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https://github.com/ziglang/zig.git
synced 2026-01-20 22:35:24 +00:00
elf: Iterate over headers w/o need for allocator
This commit is contained in:
Jay Petacat
Andrew Kelley
parent
0d31877444
commit
cf15b4c269
@ -46,9 +46,10 @@ const BinaryElfOutput = struct {
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.segments = ArrayList(*BinaryElfSegment).init(allocator),
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.sections = ArrayList(*BinaryElfSection).init(allocator),
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};
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const elf_hdrs = try std.elf.readAllHeaders(allocator, elf_file);
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const elf_hdr = try std.elf.readHeader(elf_file);
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for (elf_hdrs.section_headers) |section, i| {
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var section_headers = elf_hdr.section_header_iterator(elf_file);
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while (try section_headers.next()) |section| {
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if (sectionValidForOutput(section)) {
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const newSection = try allocator.create(BinaryElfSection);
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@ -61,7 +62,8 @@ const BinaryElfOutput = struct {
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}
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}
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for (elf_hdrs.program_headers) |phdr, i| {
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var program_headers = elf_hdr.program_header_iterator(elf_file);
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while (try program_headers.next()) |phdr| {
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if (phdr.p_type == elf.PT_LOAD) {
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const newSegment = try allocator.create(BinaryElfSegment);
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265
lib/std/elf.zig
265
lib/std/elf.zig
@ -341,6 +341,20 @@ const Header = struct {
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shentsize: u16,
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shnum: u16,
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shstrndx: u16,
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pub fn program_header_iterator(self: Header, file: File) ProgramHeaderIterator {
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return .{
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.elf_header = self,
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.file = file,
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};
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}
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pub fn section_header_iterator(self: Header, file: File) SectionHeaderIterator {
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return .{
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.elf_header = self,
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.file = file,
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};
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}
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};
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pub fn readHeader(file: File) !Header {
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@ -378,144 +392,137 @@ pub fn readHeader(file: File) !Header {
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});
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}
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/// All integers are native endian.
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pub const AllHeaders = struct {
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header: Header,
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section_headers: []Elf64_Shdr,
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program_headers: []Elf64_Phdr,
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allocator: *mem.Allocator,
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pub const ProgramHeaderIterator = struct {
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elf_header: Header,
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file: File,
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index: usize = 0,
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pub fn next(self: *ProgramHeaderIterator) !?Elf64_Phdr {
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if (self.index >= self.elf_header.phnum) return null;
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defer self.index += 1;
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if (self.elf_header.is_64) {
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var phdr: Elf64_Phdr = undefined;
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const offset = self.elf_header.phoff + @sizeOf(@TypeOf(phdr)) * self.index;
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try preadNoEof(self.file, mem.asBytes(&phdr), offset);
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// ELF endianness matches native endianness.
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if (self.elf_header.endian == std.builtin.endian) return phdr;
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// Convert fields to native endianness.
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return Elf64_Phdr{
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.p_type = @byteSwap(@TypeOf(phdr.p_type), phdr.p_type),
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.p_offset = @byteSwap(@TypeOf(phdr.p_offset), phdr.p_offset),
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.p_vaddr = @byteSwap(@TypeOf(phdr.p_vaddr), phdr.p_vaddr),
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.p_paddr = @byteSwap(@TypeOf(phdr.p_paddr), phdr.p_paddr),
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.p_filesz = @byteSwap(@TypeOf(phdr.p_filesz), phdr.p_filesz),
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.p_memsz = @byteSwap(@TypeOf(phdr.p_memsz), phdr.p_memsz),
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.p_flags = @byteSwap(@TypeOf(phdr.p_flags), phdr.p_flags),
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.p_align = @byteSwap(@TypeOf(phdr.p_align), phdr.p_align),
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};
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}
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var phdr: Elf32_Phdr = undefined;
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const offset = self.elf_header.phoff + @sizeOf(@TypeOf(phdr)) * self.index;
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try preadNoEof(self.file, mem.asBytes(&phdr), offset);
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// ELF endianness does NOT match native endianness.
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if (self.elf_header.endian != std.builtin.endian) {
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// Convert fields to native endianness.
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phdr = .{
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.p_type = @byteSwap(@TypeOf(phdr.p_type), phdr.p_type),
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.p_offset = @byteSwap(@TypeOf(phdr.p_offset), phdr.p_offset),
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.p_vaddr = @byteSwap(@TypeOf(phdr.p_vaddr), phdr.p_vaddr),
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.p_paddr = @byteSwap(@TypeOf(phdr.p_paddr), phdr.p_paddr),
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.p_filesz = @byteSwap(@TypeOf(phdr.p_filesz), phdr.p_filesz),
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.p_memsz = @byteSwap(@TypeOf(phdr.p_memsz), phdr.p_memsz),
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.p_flags = @byteSwap(@TypeOf(phdr.p_flags), phdr.p_flags),
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.p_align = @byteSwap(@TypeOf(phdr.p_align), phdr.p_align),
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};
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}
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// Convert 32-bit header to 64-bit.
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return Elf64_Phdr{
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.p_type = phdr.p_type,
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.p_offset = phdr.p_offset,
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.p_vaddr = phdr.p_vaddr,
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.p_paddr = phdr.p_paddr,
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.p_filesz = phdr.p_filesz,
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.p_memsz = phdr.p_memsz,
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.p_flags = phdr.p_flags,
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.p_align = phdr.p_align,
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};
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}
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};
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pub fn readAllHeaders(allocator: *mem.Allocator, file: File) !AllHeaders {
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var hdrs: AllHeaders = .{
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.allocator = allocator,
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.header = try readHeader(file),
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.section_headers = undefined,
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.program_headers = undefined,
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};
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const is_64 = hdrs.header.is_64;
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const need_bswap = hdrs.header.endian != std.builtin.endian;
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pub const SectionHeaderIterator = struct {
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elf_header: Header,
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file: File,
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index: usize = 0,
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hdrs.section_headers = try allocator.alloc(Elf64_Shdr, hdrs.header.shnum);
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errdefer allocator.free(hdrs.section_headers);
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pub fn next(self: *SectionHeaderIterator) !?Elf64_Shdr {
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if (self.index >= self.elf_header.shnum) return null;
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defer self.index += 1;
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hdrs.program_headers = try allocator.alloc(Elf64_Phdr, hdrs.header.phnum);
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errdefer allocator.free(hdrs.program_headers);
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if (self.elf_header.is_64) {
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var shdr: Elf64_Shdr = undefined;
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const offset = self.elf_header.phoff + @sizeOf(@TypeOf(shdr)) * self.index;
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try preadNoEof(self.file, mem.asBytes(&shdr), offset);
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// If the ELF file is 64-bit and same-endianness, then all we have to do is
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// yeet the bytes into memory.
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// If only the endianness is different, they can be simply byte swapped.
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if (is_64) {
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const shdr_buf = std.mem.sliceAsBytes(hdrs.section_headers);
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const phdr_buf = std.mem.sliceAsBytes(hdrs.program_headers);
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try preadNoEof(file, shdr_buf, hdrs.header.shoff);
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try preadNoEof(file, phdr_buf, hdrs.header.phoff);
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// ELF endianness matches native endianness.
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if (self.elf_header.endian == std.builtin.endian) return shdr;
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if (need_bswap) {
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for (hdrs.section_headers) |*shdr| {
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shdr.* = .{
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.sh_name = @byteSwap(@TypeOf(shdr.sh_name), shdr.sh_name),
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.sh_type = @byteSwap(@TypeOf(shdr.sh_type), shdr.sh_type),
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.sh_flags = @byteSwap(@TypeOf(shdr.sh_flags), shdr.sh_flags),
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.sh_addr = @byteSwap(@TypeOf(shdr.sh_addr), shdr.sh_addr),
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.sh_offset = @byteSwap(@TypeOf(shdr.sh_offset), shdr.sh_offset),
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.sh_size = @byteSwap(@TypeOf(shdr.sh_size), shdr.sh_size),
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.sh_link = @byteSwap(@TypeOf(shdr.sh_link), shdr.sh_link),
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.sh_info = @byteSwap(@TypeOf(shdr.sh_info), shdr.sh_info),
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.sh_addralign = @byteSwap(@TypeOf(shdr.sh_addralign), shdr.sh_addralign),
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.sh_entsize = @byteSwap(@TypeOf(shdr.sh_entsize), shdr.sh_entsize),
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};
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}
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for (hdrs.program_headers) |*phdr| {
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phdr.* = .{
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.p_type = @byteSwap(@TypeOf(phdr.p_type), phdr.p_type),
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.p_offset = @byteSwap(@TypeOf(phdr.p_offset), phdr.p_offset),
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.p_vaddr = @byteSwap(@TypeOf(phdr.p_vaddr), phdr.p_vaddr),
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.p_paddr = @byteSwap(@TypeOf(phdr.p_paddr), phdr.p_paddr),
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.p_filesz = @byteSwap(@TypeOf(phdr.p_filesz), phdr.p_filesz),
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.p_memsz = @byteSwap(@TypeOf(phdr.p_memsz), phdr.p_memsz),
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.p_flags = @byteSwap(@TypeOf(phdr.p_flags), phdr.p_flags),
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.p_align = @byteSwap(@TypeOf(phdr.p_align), phdr.p_align),
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};
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}
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// Convert fields to native endianness.
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return Elf64_Shdr{
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.sh_name = @byteSwap(@TypeOf(shdr.sh_name), shdr.sh_name),
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.sh_type = @byteSwap(@TypeOf(shdr.sh_type), shdr.sh_type),
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.sh_flags = @byteSwap(@TypeOf(shdr.sh_flags), shdr.sh_flags),
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.sh_addr = @byteSwap(@TypeOf(shdr.sh_addr), shdr.sh_addr),
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.sh_offset = @byteSwap(@TypeOf(shdr.sh_offset), shdr.sh_offset),
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.sh_size = @byteSwap(@TypeOf(shdr.sh_size), shdr.sh_size),
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.sh_link = @byteSwap(@TypeOf(shdr.sh_link), shdr.sh_link),
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.sh_info = @byteSwap(@TypeOf(shdr.sh_info), shdr.sh_info),
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.sh_addralign = @byteSwap(@TypeOf(shdr.sh_addralign), shdr.sh_addralign),
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.sh_entsize = @byteSwap(@TypeOf(shdr.sh_entsize), shdr.sh_entsize),
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};
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}
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return hdrs;
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var shdr: Elf32_Shdr = undefined;
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const offset = self.elf_header.shoff + @sizeOf(@TypeOf(shdr)) * self.index;
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try preadNoEof(self.file, mem.asBytes(&shdr), offset);
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// ELF endianness does NOT match native endianness.
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if (self.elf_header.endian != std.builtin.endian) {
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// Convert fields to native endianness.
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shdr = .{
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.sh_name = @byteSwap(@TypeOf(shdr.sh_name), shdr.sh_name),
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.sh_type = @byteSwap(@TypeOf(shdr.sh_type), shdr.sh_type),
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.sh_flags = @byteSwap(@TypeOf(shdr.sh_flags), shdr.sh_flags),
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.sh_addr = @byteSwap(@TypeOf(shdr.sh_addr), shdr.sh_addr),
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.sh_offset = @byteSwap(@TypeOf(shdr.sh_offset), shdr.sh_offset),
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.sh_size = @byteSwap(@TypeOf(shdr.sh_size), shdr.sh_size),
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.sh_link = @byteSwap(@TypeOf(shdr.sh_link), shdr.sh_link),
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.sh_info = @byteSwap(@TypeOf(shdr.sh_info), shdr.sh_info),
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.sh_addralign = @byteSwap(@TypeOf(shdr.sh_addralign), shdr.sh_addralign),
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.sh_entsize = @byteSwap(@TypeOf(shdr.sh_entsize), shdr.sh_entsize),
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};
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}
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// Convert 32-bit header to 64-bit.
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return Elf64_Shdr{
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.sh_name = shdr.sh_name,
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.sh_type = shdr.sh_type,
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.sh_flags = shdr.sh_flags,
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.sh_addr = shdr.sh_addr,
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.sh_offset = shdr.sh_offset,
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.sh_size = shdr.sh_size,
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.sh_link = shdr.sh_link,
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.sh_info = shdr.sh_info,
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.sh_addralign = shdr.sh_addralign,
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.sh_entsize = shdr.sh_entsize,
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};
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}
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const shdrs_32 = try allocator.alloc(Elf32_Shdr, hdrs.header.shnum);
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defer allocator.free(shdrs_32);
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const phdrs_32 = try allocator.alloc(Elf32_Phdr, hdrs.header.phnum);
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defer allocator.free(phdrs_32);
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const shdr_buf = std.mem.sliceAsBytes(shdrs_32);
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const phdr_buf = std.mem.sliceAsBytes(phdrs_32);
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try preadNoEof(file, shdr_buf, hdrs.header.shoff);
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try preadNoEof(file, phdr_buf, hdrs.header.phoff);
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if (need_bswap) {
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for (hdrs.section_headers) |*shdr, i| {
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const o = shdrs_32[i];
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shdr.* = .{
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.sh_name = @byteSwap(@TypeOf(o.sh_name), o.sh_name),
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.sh_type = @byteSwap(@TypeOf(o.sh_type), o.sh_type),
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.sh_flags = @byteSwap(@TypeOf(o.sh_flags), o.sh_flags),
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.sh_addr = @byteSwap(@TypeOf(o.sh_addr), o.sh_addr),
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.sh_offset = @byteSwap(@TypeOf(o.sh_offset), o.sh_offset),
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.sh_size = @byteSwap(@TypeOf(o.sh_size), o.sh_size),
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.sh_link = @byteSwap(@TypeOf(o.sh_link), o.sh_link),
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.sh_info = @byteSwap(@TypeOf(o.sh_info), o.sh_info),
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.sh_addralign = @byteSwap(@TypeOf(o.sh_addralign), o.sh_addralign),
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.sh_entsize = @byteSwap(@TypeOf(o.sh_entsize), o.sh_entsize),
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};
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}
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for (hdrs.program_headers) |*phdr, i| {
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const o = phdrs_32[i];
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phdr.* = .{
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.p_type = @byteSwap(@TypeOf(o.p_type), o.p_type),
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.p_offset = @byteSwap(@TypeOf(o.p_offset), o.p_offset),
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.p_vaddr = @byteSwap(@TypeOf(o.p_vaddr), o.p_vaddr),
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.p_paddr = @byteSwap(@TypeOf(o.p_paddr), o.p_paddr),
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.p_filesz = @byteSwap(@TypeOf(o.p_filesz), o.p_filesz),
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.p_memsz = @byteSwap(@TypeOf(o.p_memsz), o.p_memsz),
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.p_flags = @byteSwap(@TypeOf(o.p_flags), o.p_flags),
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.p_align = @byteSwap(@TypeOf(o.p_align), o.p_align),
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};
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}
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} else {
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for (hdrs.section_headers) |*shdr, i| {
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const o = shdrs_32[i];
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shdr.* = .{
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.sh_name = o.sh_name,
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.sh_type = o.sh_type,
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.sh_flags = o.sh_flags,
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.sh_addr = o.sh_addr,
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.sh_offset = o.sh_offset,
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.sh_size = o.sh_size,
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.sh_link = o.sh_link,
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.sh_info = o.sh_info,
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.sh_addralign = o.sh_addralign,
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.sh_entsize = o.sh_entsize,
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};
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}
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for (hdrs.program_headers) |*phdr, i| {
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const o = phdrs_32[i];
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phdr.* = .{
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.p_type = o.p_type,
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.p_offset = o.p_offset,
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.p_vaddr = o.p_vaddr,
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.p_paddr = o.p_paddr,
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.p_filesz = o.p_filesz,
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.p_memsz = o.p_memsz,
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.p_flags = o.p_flags,
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.p_align = o.p_align,
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};
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}
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}
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return hdrs;
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}
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};
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pub fn int(is_64: bool, need_bswap: bool, int_32: anytype, int_64: anytype) @TypeOf(int_64) {
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if (is_64) {
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