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Elf2: improve dynamic linking support
This commit is contained in:
Jacob Young
parent
c9fa8e46df
commit
4f7a3c23e7
1 changed files with 109 additions and 23 deletions
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@ -743,7 +743,7 @@ pub const Reloc = extern struct {
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}
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};
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pub fn apply(reloc: *const Reloc, elf: *Elf) void {
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pub fn apply(reloc: *Reloc, elf: *Elf) void {
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assert(elf.ehdrField(.type) != .REL);
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const loc_ni = reloc.loc.get(elf).ni;
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switch (loc_ni) {
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@ -766,7 +766,7 @@ pub const Reloc = extern struct {
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elf.targetLoad(&target_sym.value) +% @as(u64, @bitCast(reloc.addend));
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switch (elf.ehdrField(.machine)) {
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else => |machine| @panic(@tagName(machine)),
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.X86_64 => switch (reloc.type.X86_64) {
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.X86_64 => type: switch (reloc.type.X86_64) {
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else => |kind| @panic(@tagName(kind)),
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.@"64" => std.mem.writeInt(
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u64,
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@ -852,6 +852,75 @@ pub const Reloc = extern struct {
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elf.targetLoad(&target_sym.size) +% @as(u64, @bitCast(reloc.addend)),
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target_endian,
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),
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.GOTPCRELX => {
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relax: switch (Symbol.Index.Shndx.fromSection(
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elf.targetLoad(&target_sym.shndx),
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)) {
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.UNDEF => {},
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else => {
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const inst = (loc_slice.ptr - 2)[0..2];
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if (inst[0] != 0xff) break :relax;
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const mod_rm: packed struct {
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rm: u3,
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opcode: u3,
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mod: u2,
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} = @bitCast(inst[1]);
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if (mod_rm.mod != 0b00) break :relax;
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if (mod_rm.rm != 0b101) break :relax;
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switch (mod_rm.opcode) {
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0, // incl 0x0(%rip)
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1, // decl 0x0(%rip)
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3, // lcall *0x0(%rip)
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5, // ljmp *0x0(%rip)
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6, // push 0x0(%rip)
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7, // ud 0x0(%rip)
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=> break :relax,
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2 => { // call *0x0(%rip)
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inst[1] = 0xe8; // call 0
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},
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4 => { // jmp *0x0(%rip)
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inst[1] = 0xe9; // jmp 0
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},
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}
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inst[0] = 0x48; // rex.W
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reloc.type.X86_64 = .PC32;
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continue :type .PC32;
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},
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}
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@panic("relax failure");
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},
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.REX_GOTPCRELX => {
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relax: switch (Symbol.Index.Shndx.fromSection(
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elf.targetLoad(&target_sym.shndx),
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)) {
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.UNDEF => {},
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else => {
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const inst = (loc_slice.ptr - 3)[0..3];
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const rex: packed struct {
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b: bool,
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x: bool,
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r: bool,
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w: bool,
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encoded4: u4,
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} = @bitCast(inst[0]);
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if (rex.encoded4 != 0b0100) break :relax;
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if (!rex.w) break :relax;
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if (rex.x) break :relax;
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if (inst[1] != 0x8b) break :relax; // mov
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const mod_rm: packed struct {
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rm: u3,
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r: u3,
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mod: u2,
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} = @bitCast(inst[2]);
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if (mod_rm.mod != 0b00) break :relax;
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if (mod_rm.rm != 0b101) break :relax;
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inst[1] = 0x8d; // lea
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reloc.type.X86_64 = .PC32;
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continue :type .PC32;
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},
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}
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@panic("relax failure");
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},
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},
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}
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},
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@ -1174,7 +1243,7 @@ fn initHeaders(
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}
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assert(elf.ni.shdr == try elf.mf.addLastChildNode(gpa, elf.ni.file, .{
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.size = elf.ehdrField(.shentsize) * elf.ehdrField(.shnum),
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.size = @as(u64, elf.ehdrField(.shentsize)) * elf.ehdrField(.shnum),
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.alignment = elf.mf.flags.block_size,
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.moved = true,
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.resized = true,
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@ -1191,7 +1260,7 @@ fn initHeaders(
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elf.phdrs.items[rodata_phndx] = elf.ni.rodata;
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assert(elf.ni.phdr == try elf.mf.addOnlyChildNode(gpa, elf.ni.rodata, .{
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.size = elf.ehdrField(.phentsize) * elf.ehdrField(.phnum),
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.size = @as(u64, elf.ehdrField(.phentsize)) * elf.ehdrField(.phnum),
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.alignment = addr_align,
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.moved = true,
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.resized = true,
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@ -2123,7 +2192,7 @@ fn loadObject(
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if (ehdr.machine != elf.ehdrField(.machine))
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return diags.failParse(path, "bad machine", .{});
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if (ehdr.shoff == 0 or ehdr.shnum <= 1) return;
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if (ehdr.shoff + ehdr.shentsize * ehdr.shnum > fl.size)
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if (ehdr.shoff + @as(ElfN.Off, ehdr.shentsize) * ehdr.shnum > fl.size)
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return diags.failParse(path, "bad section header location", .{});
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if (ehdr.shentsize < @sizeOf(ElfN.Shdr))
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return diags.failParse(path, "unsupported shentsize", .{});
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@ -2228,11 +2297,11 @@ fn loadObject(
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si.* = .null;
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const input_sym = try r.peekStruct(ElfN.Sym, target_endian);
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try r.discardAll64(symtab.shdr.entsize);
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if (input_sym.name >= strtab.len or input_sym.shndx == std.elf.SHN_UNDEF or
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input_sym.shndx >= ehdr.shnum) continue;
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if (input_sym.name >= strtab.len or input_sym.shndx >= ehdr.shnum) continue;
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switch (input_sym.info.type) {
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.NOTYPE, .OBJECT, .FUNC => {},
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.SECTION => {
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if (input_sym.shndx == std.elf.SHN_UNDEF) continue;
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const section = §ions[input_sym.shndx];
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if (input_sym.value == section.shdr.addr) si.* = section.si;
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continue;
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@ -2254,21 +2323,30 @@ fn loadObject(
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switch (input_sym.info.bind) {
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else => {},
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.GLOBAL => {
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const gop = elf.globals.getOrPutAssumeCapacity(elf.targetLoad(
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&@field(elf.symPtr(si.*), @tagName(class)).name,
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));
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if (gop.found_existing) switch (elf.targetLoad(
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switch (elf.symPtr(gop.value_ptr.*)) {
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inline else => |sym| &sym.info,
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const sym = @field(elf.symPtr(si.*), @tagName(class));
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const gop =
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elf.globals.getOrPutAssumeCapacity(elf.targetLoad(&sym.name));
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if (gop.found_existing) switch (input_sym.shndx) {
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std.elf.SHN_UNDEF => {},
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else => {
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const existing_sym =
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@field(elf.symPtr(gop.value_ptr.*), @tagName(class));
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switch (elf.targetLoad(&existing_sym.info).bind) {
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else => unreachable,
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.GLOBAL => switch (elf.targetLoad(&existing_sym.shndx)) {
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std.elf.SHN_UNDEF => {},
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else => return diags.failParse(
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path,
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"multiple definitions of '{s}'",
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.{name},
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),
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},
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.WEAK => {},
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}
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existing_sym.size = sym.size;
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existing_sym.shndx = sym.shndx;
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gop.value_ptr.flushMoved(elf, input_sym.value);
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},
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).bind) {
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else => unreachable,
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.GLOBAL => return diags.failParse(
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path,
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"multiple definitions of '{s}'",
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.{name},
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),
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.WEAK => {},
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};
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gop.value_ptr.* = si.*;
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},
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@ -2337,7 +2415,7 @@ fn loadDso(elf: *Elf, path: std.Build.Cache.Path, fr: *Io.File.Reader) !void {
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const r = &fr.interface;
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log.debug("loadDso({f})", .{path.fmtEscapeString()});
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const ident = try r.peek(std.elf.EI.NIDENT);
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const ident = try r.peek(std.elf.EI.OSABI);
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if (!std.mem.eql(u8, ident[0..std.elf.MAGIC.len], std.elf.MAGIC)) return error.BadMagic;
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if (!std.mem.eql(u8, ident[std.elf.MAGIC.len..], elf.mf.contents[std.elf.MAGIC.len..ident.len]))
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return diags.failParse(path, "bad ident", .{});
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@ -2621,7 +2699,7 @@ fn addSection(elf: *Elf, segment_ni: MappedFile.Node.Index, opts: struct {
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},
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};
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assert(shndx < @intFromEnum(Symbol.Index.Shndx.LORESERVE));
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break :shndx .{ @enumFromInt(shndx), elf.targetLoad(&ehdr.shentsize) * shnum };
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break :shndx .{ @enumFromInt(shndx), @as(u64, elf.targetLoad(&ehdr.shentsize)) * shnum };
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},
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};
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_, const shdr_node_size = elf.ni.shdr.location(&elf.mf).resolve(&elf.mf);
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@ -3720,6 +3798,14 @@ fn updateExportsInner(
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},
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}
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export_si.flushMoved(elf, value);
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if (elf.dynsym.getIndex(export_si)) |export_dsi| switch (elf.dynsymSlice()) {
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inline else => |dynsyms| {
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const dynsym = &dynsyms[export_dsi];
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elf.targetStore(&dynsym.value, @intCast(value));
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dynsym.size = @intCast(size);
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dynsym.shndx = shndx;
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},
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};
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}
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}
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