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MachO.zig
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MachO.zig
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const MachO = @This();
const std = @import("std");
const Allocator = std.mem.Allocator;
const assert = std.debug.assert;
const fs = std.fs;
const log = std.log.scoped(.link);
const macho = std.macho;
const codegen = @import("../codegen.zig");
const math = std.math;
const mem = std.mem;
const trace = @import("../tracy.zig").trace;
const Type = @import("../type.zig").Type;
const build_options = @import("build_options");
const Module = @import("../Module.zig");
const Compilation = @import("../Compilation.zig");
const link = @import("../link.zig");
const File = link.File;
const Cache = @import("../Cache.zig");
const target_util = @import("../target.zig");
const Trie = @import("MachO/Trie.zig");
pub const base_tag: File.Tag = File.Tag.macho;
const LoadCommand = union(enum) {
Segment: macho.segment_command_64,
LinkeditData: macho.linkedit_data_command,
Symtab: macho.symtab_command,
Dysymtab: macho.dysymtab_command,
DyldInfo: macho.dyld_info_command,
Dylinker: macho.dylinker_command,
Dylib: macho.dylib_command,
EntryPoint: macho.entry_point_command,
pub fn cmdsize(self: LoadCommand) u32 {
return switch (self) {
.Segment => |x| x.cmdsize,
.LinkeditData => |x| x.cmdsize,
.Symtab => |x| x.cmdsize,
.Dysymtab => |x| x.cmdsize,
.DyldInfo => |x| x.cmdsize,
.Dylinker => |x| x.cmdsize,
.Dylib => |x| x.cmdsize,
.EntryPoint => |x| x.cmdsize,
};
}
pub fn write(self: LoadCommand, file: *fs.File, offset: u64) !void {
return switch (self) {
.Segment => |cmd| writeGeneric(cmd, file, offset),
.LinkeditData => |cmd| writeGeneric(cmd, file, offset),
.Symtab => |cmd| writeGeneric(cmd, file, offset),
.Dysymtab => |cmd| writeGeneric(cmd, file, offset),
.DyldInfo => |cmd| writeGeneric(cmd, file, offset),
.Dylinker => |cmd| writeGeneric(cmd, file, offset),
.Dylib => |cmd| writeGeneric(cmd, file, offset),
.EntryPoint => |cmd| writeGeneric(cmd, file, offset),
};
}
fn writeGeneric(cmd: anytype, file: *fs.File, offset: u64) !void {
const slice = [1]@TypeOf(cmd){cmd};
return file.pwriteAll(mem.sliceAsBytes(slice[0..1]), offset);
}
};
base: File,
/// Table of all load commands
load_commands: std.ArrayListUnmanaged(LoadCommand) = .{},
/// __PAGEZERO segment
pagezero_segment_cmd_index: ?u16 = null,
/// __TEXT segment
text_segment_cmd_index: ?u16 = null,
/// __DATA segment
data_segment_cmd_index: ?u16 = null,
/// __LINKEDIT segment
linkedit_segment_cmd_index: ?u16 = null,
/// Dyld info
dyld_info_cmd_index: ?u16 = null,
/// Symbol table
symtab_cmd_index: ?u16 = null,
/// Dynamic symbol table
dysymtab_cmd_index: ?u16 = null,
/// Path to dyld linker
dylinker_cmd_index: ?u16 = null,
/// Path to libSystem
libsystem_cmd_index: ?u16 = null,
/// Data-in-code section of __LINKEDIT segment
data_in_code_cmd_index: ?u16 = null,
/// Address to entry point function
function_starts_cmd_index: ?u16 = null,
/// Main/entry point
/// Specifies offset wrt __TEXT segment start address to the main entry point
/// of the binary.
main_cmd_index: ?u16 = null,
/// Table of all sections
sections: std.ArrayListUnmanaged(macho.section_64) = .{},
/// __TEXT,__text section
text_section_index: ?u16 = null,
/// __DATA,__got section
got_section_index: ?u16 = null,
entry_addr: ?u64 = null,
/// Table of all local symbols
/// Internally references string table for names (which are optional).
local_symbols: std.ArrayListUnmanaged(macho.nlist_64) = .{},
/// Table of all defined global symbols
global_symbols: std.ArrayListUnmanaged(macho.nlist_64) = .{},
/// Table of all undefined symbols
undef_symbols: std.ArrayListUnmanaged(macho.nlist_64) = .{},
global_symbol_free_list: std.ArrayListUnmanaged(u32) = .{},
dyld_stub_binder_index: ?u16 = null,
/// Table of symbol names aka the string table.
string_table: std.ArrayListUnmanaged(u8) = .{},
/// Table of symbol vaddr values. The values is the absolute vaddr value.
/// If the vaddr of the executable __TEXT segment vaddr changes, the entire offset
/// table needs to be rewritten.
offset_table: std.ArrayListUnmanaged(u64) = .{},
error_flags: File.ErrorFlags = File.ErrorFlags{},
cmd_table_dirty: bool = false,
/// Pointer to the last allocated text block
last_text_block: ?*TextBlock = null,
/// `alloc_num / alloc_den` is the factor of padding when allocating.
const alloc_num = 4;
const alloc_den = 3;
/// Default path to dyld
/// TODO instead of hardcoding it, we should probably look through some env vars and search paths
/// instead but this will do for now.
const DEFAULT_DYLD_PATH: [*:0]const u8 = "/usr/lib/dyld";
/// Default lib search path
/// TODO instead of hardcoding it, we should probably look through some env vars and search paths
/// instead but this will do for now.
const DEFAULT_LIB_SEARCH_PATH: []const u8 = "/usr/lib";
const LIB_SYSTEM_NAME: [*:0]const u8 = "System";
/// TODO we should search for libSystem and fail if it doesn't exist, instead of hardcoding it
const LIB_SYSTEM_PATH: [*:0]const u8 = DEFAULT_LIB_SEARCH_PATH ++ "/libSystem.B.dylib";
pub const TextBlock = struct {
/// Each decl always gets a local symbol with the fully qualified name.
/// The vaddr and size are found here directly.
/// The file offset is found by computing the vaddr offset from the section vaddr
/// the symbol references, and adding that to the file offset of the section.
/// If this field is 0, it means the codegen size = 0 and there is no symbol or
/// offset table entry.
local_sym_index: u32,
/// Index into offset table
/// This field is undefined for symbols with size = 0.
offset_table_index: u32,
/// Size of this text block
/// Unlike in Elf, we need to store the size of this symbol as part of
/// the TextBlock since macho.nlist_64 lacks this information.
size: u64,
/// Points to the previous and next neighbours
prev: ?*TextBlock,
next: ?*TextBlock,
pub const empty = TextBlock{
.local_sym_index = 0,
.offset_table_index = undefined,
.size = 0,
.prev = null,
.next = null,
};
};
pub const Export = struct {
sym_index: ?u32 = null,
};
pub const SrcFn = struct {
pub const empty = SrcFn{};
};
pub fn openPath(allocator: *Allocator, sub_path: []const u8, options: link.Options) !*MachO {
assert(options.object_format == .macho);
if (options.use_llvm) return error.LLVM_BackendIsTODO_ForMachO; // TODO
if (options.use_lld) return error.LLD_LinkingIsTODO_ForMachO; // TODO
const file = try options.emit.?.directory.handle.createFile(sub_path, .{
.truncate = false,
.read = true,
.mode = link.determineMode(options),
});
errdefer file.close();
const self = try createEmpty(allocator, options);
errdefer self.base.destroy();
self.base.file = file;
// Index 0 is always a null symbol.
try self.local_symbols.append(allocator, .{
.n_strx = 0,
.n_type = 0,
.n_sect = 0,
.n_desc = 0,
.n_value = 0,
});
switch (options.output_mode) {
.Exe => {},
.Obj => {},
.Lib => return error.TODOImplementWritingLibFiles,
}
try self.populateMissingMetadata();
return self;
}
pub fn createEmpty(gpa: *Allocator, options: link.Options) !*MachO {
const self = try gpa.create(MachO);
self.* = .{
.base = .{
.tag = .macho,
.options = options,
.allocator = gpa,
.file = null,
},
};
return self;
}
pub fn flush(self: *MachO, comp: *Compilation) !void {
if (build_options.have_llvm and self.base.options.use_lld) {
return self.linkWithLLD(comp);
} else {
switch (self.base.options.effectiveOutputMode()) {
.Exe, .Obj => {},
.Lib => return error.TODOImplementWritingLibFiles,
}
return self.flushModule(comp);
}
}
pub fn flushModule(self: *MachO, comp: *Compilation) !void {
const tracy = trace(@src());
defer tracy.end();
// Unfortunately these have to be buffered and done at the end because MachO does not allow
// mixing local, global and undefined symbols within a symbol table.
try self.writeAllGlobalSymbols();
try self.writeAllUndefSymbols();
try self.writeStringTable();
switch (self.base.options.output_mode) {
.Exe => {
// Write export trie.
try self.writeExportTrie();
if (self.entry_addr) |addr| {
// Update LC_MAIN with entry offset
const text_segment = self.load_commands.items[self.text_segment_cmd_index.?].Segment;
const main_cmd = &self.load_commands.items[self.main_cmd_index.?].EntryPoint;
main_cmd.entryoff = addr - text_segment.vmaddr;
}
{
// Update dynamic symbol table.
const nlocals = @intCast(u32, self.local_symbols.items.len);
const nglobals = @intCast(u32, self.global_symbols.items.len);
const nundefs = @intCast(u32, self.undef_symbols.items.len);
const dysymtab = &self.load_commands.items[self.dysymtab_cmd_index.?].Dysymtab;
dysymtab.nlocalsym = nlocals;
dysymtab.iextdefsym = nlocals;
dysymtab.nextdefsym = nglobals;
dysymtab.iundefsym = nlocals + nglobals;
dysymtab.nundefsym = nundefs;
}
{
// Write path to dyld loader.
var off: usize = @sizeOf(macho.mach_header_64);
for (self.load_commands.items) |cmd| {
if (cmd == .Dylinker) break;
off += cmd.cmdsize();
}
const cmd = &self.load_commands.items[self.dylinker_cmd_index.?].Dylinker;
off += cmd.name;
log.debug("writing LC_LOAD_DYLINKER path to dyld at 0x{x}\n", .{off});
try self.base.file.?.pwriteAll(mem.spanZ(DEFAULT_DYLD_PATH), off);
}
{
// Write path to libSystem.
var off: usize = @sizeOf(macho.mach_header_64);
for (self.load_commands.items) |cmd| {
if (cmd == .Dylib) break;
off += cmd.cmdsize();
}
const cmd = &self.load_commands.items[self.libsystem_cmd_index.?].Dylib;
off += cmd.dylib.name;
log.debug("writing LC_LOAD_DYLIB path to libSystem at 0x{x}\n", .{off});
try self.base.file.?.pwriteAll(mem.spanZ(LIB_SYSTEM_PATH), off);
}
},
.Obj => {},
.Lib => return error.TODOImplementWritingLibFiles,
}
if (self.cmd_table_dirty) try self.writeCmdHeaders();
{
// Update symbol table.
const nlocals = @intCast(u32, self.local_symbols.items.len);
const nglobals = @intCast(u32, self.global_symbols.items.len);
const nundefs = @intCast(u32, self.undef_symbols.items.len);
const symtab = &self.load_commands.items[self.symtab_cmd_index.?].Symtab;
symtab.nsyms = nlocals + nglobals + nundefs;
}
if (self.entry_addr == null and self.base.options.output_mode == .Exe) {
log.debug("flushing. no_entry_point_found = true\n", .{});
self.error_flags.no_entry_point_found = true;
} else {
log.debug("flushing. no_entry_point_found = false\n", .{});
self.error_flags.no_entry_point_found = false;
try self.writeMachOHeader();
}
}
fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
const tracy = trace(@src());
defer tracy.end();
var arena_allocator = std.heap.ArenaAllocator.init(self.base.allocator);
defer arena_allocator.deinit();
const arena = &arena_allocator.allocator;
const directory = self.base.options.emit.?.directory; // Just an alias to make it shorter to type.
// If there is no Zig code to compile, then we should skip flushing the output file because it
// will not be part of the linker line anyway.
const module_obj_path: ?[]const u8 = if (self.base.options.module) |module| blk: {
const use_stage1 = build_options.is_stage1 and self.base.options.use_llvm;
if (use_stage1) {
const obj_basename = try std.zig.binNameAlloc(arena, .{
.root_name = self.base.options.root_name,
.target = self.base.options.target,
.output_mode = .Obj,
});
const o_directory = self.base.options.module.?.zig_cache_artifact_directory;
const full_obj_path = try o_directory.join(arena, &[_][]const u8{obj_basename});
break :blk full_obj_path;
}
try self.flushModule(comp);
const obj_basename = self.base.intermediary_basename.?;
const full_obj_path = try directory.join(arena, &[_][]const u8{obj_basename});
break :blk full_obj_path;
} else null;
const is_lib = self.base.options.output_mode == .Lib;
const is_dyn_lib = self.base.options.link_mode == .Dynamic and is_lib;
const is_exe_or_dyn_lib = is_dyn_lib or self.base.options.output_mode == .Exe;
const target = self.base.options.target;
const stack_size = self.base.options.stack_size_override orelse 16777216;
const allow_shlib_undefined = self.base.options.allow_shlib_undefined orelse !self.base.options.is_native_os;
const id_symlink_basename = "lld.id";
var man: Cache.Manifest = undefined;
defer if (!self.base.options.disable_lld_caching) man.deinit();
var digest: [Cache.hex_digest_len]u8 = undefined;
if (!self.base.options.disable_lld_caching) {
man = comp.cache_parent.obtain();
// We are about to obtain this lock, so here we give other processes a chance first.
self.base.releaseLock();
try man.addOptionalFile(self.base.options.linker_script);
try man.addOptionalFile(self.base.options.version_script);
try man.addListOfFiles(self.base.options.objects);
for (comp.c_object_table.items()) |entry| {
_ = try man.addFile(entry.key.status.success.object_path, null);
}
try man.addOptionalFile(module_obj_path);
// We can skip hashing libc and libc++ components that we are in charge of building from Zig
// installation sources because they are always a product of the compiler version + target information.
man.hash.add(stack_size);
man.hash.add(self.base.options.rdynamic);
man.hash.addListOfBytes(self.base.options.extra_lld_args);
man.hash.addListOfBytes(self.base.options.lib_dirs);
man.hash.addListOfBytes(self.base.options.framework_dirs);
man.hash.addListOfBytes(self.base.options.frameworks);
man.hash.addListOfBytes(self.base.options.rpath_list);
man.hash.add(self.base.options.is_compiler_rt_or_libc);
man.hash.add(self.base.options.z_nodelete);
man.hash.add(self.base.options.z_defs);
if (is_dyn_lib) {
man.hash.addOptional(self.base.options.version);
}
man.hash.addStringSet(self.base.options.system_libs);
man.hash.add(allow_shlib_undefined);
man.hash.add(self.base.options.bind_global_refs_locally);
// We don't actually care whether it's a cache hit or miss; we just need the digest and the lock.
_ = try man.hit();
digest = man.final();
var prev_digest_buf: [digest.len]u8 = undefined;
const prev_digest: []u8 = directory.handle.readLink(id_symlink_basename, &prev_digest_buf) catch |err| blk: {
log.debug("MachO LLD new_digest={} readlink error: {}", .{ digest, @errorName(err) });
// Handle this as a cache miss.
break :blk prev_digest_buf[0..0];
};
if (mem.eql(u8, prev_digest, &digest)) {
log.debug("MachO LLD digest={} match - skipping invocation", .{digest});
// Hot diggity dog! The output binary is already there.
self.base.lock = man.toOwnedLock();
return;
}
log.debug("MachO LLD prev_digest={} new_digest={}", .{ prev_digest, digest });
// We are about to change the output file to be different, so we invalidate the build hash now.
directory.handle.deleteFile(id_symlink_basename) catch |err| switch (err) {
error.FileNotFound => {},
else => |e| return e,
};
}
const full_out_path = try directory.join(arena, &[_][]const u8{self.base.options.emit.?.sub_path});
if (self.base.options.output_mode == .Obj) {
// LLD's MachO driver does not support the equvialent of `-r` so we do a simple file copy
// here. TODO: think carefully about how we can avoid this redundant operation when doing
// build-obj. See also the corresponding TODO in linkAsArchive.
const the_object_path = blk: {
if (self.base.options.objects.len != 0)
break :blk self.base.options.objects[0];
if (comp.c_object_table.count() != 0)
break :blk comp.c_object_table.items()[0].key.status.success.object_path;
if (module_obj_path) |p|
break :blk p;
// TODO I think this is unreachable. Audit this situation when solving the above TODO
// regarding eliding redundant object -> object transformations.
return error.NoObjectsToLink;
};
// This can happen when using --enable-cache and using the stage1 backend. In this case
// we can skip the file copy.
if (!mem.eql(u8, the_object_path, full_out_path)) {
try fs.cwd().copyFile(the_object_path, fs.cwd(), full_out_path, .{});
}
} else {
// Create an LLD command line and invoke it.
var argv = std.ArrayList([]const u8).init(self.base.allocator);
defer argv.deinit();
// Even though we're calling LLD as a library it thinks the first argument is its own exe name.
try argv.append("lld");
try argv.append("-error-limit");
try argv.append("0");
try argv.append("-demangle");
if (self.base.options.rdynamic) {
try argv.append("--export-dynamic");
}
try argv.appendSlice(self.base.options.extra_lld_args);
if (self.base.options.z_nodelete) {
try argv.append("-z");
try argv.append("nodelete");
}
if (self.base.options.z_defs) {
try argv.append("-z");
try argv.append("defs");
}
if (is_dyn_lib) {
try argv.append("-static");
} else {
try argv.append("-dynamic");
}
if (is_dyn_lib) {
try argv.append("-dylib");
if (self.base.options.version) |ver| {
const compat_vers = try std.fmt.allocPrint(arena, "{d}.0.0", .{ver.major});
try argv.append("-compatibility_version");
try argv.append(compat_vers);
const cur_vers = try std.fmt.allocPrint(arena, "{d}.{d}.{d}", .{ ver.major, ver.minor, ver.patch });
try argv.append("-current_version");
try argv.append(cur_vers);
}
// TODO getting an error when running an executable when doing this rpath thing
//Buf *dylib_install_name = buf_sprintf("@rpath/lib%s.%" ZIG_PRI_usize ".dylib",
// buf_ptr(g->root_out_name), g->version_major);
//try argv.append("-install_name");
//try argv.append(buf_ptr(dylib_install_name));
}
try argv.append("-arch");
try argv.append(darwinArchString(target.cpu.arch));
switch (target.os.tag) {
.macosx => {
try argv.append("-macosx_version_min");
},
.ios, .tvos, .watchos => switch (target.cpu.arch) {
.i386, .x86_64 => {
try argv.append("-ios_simulator_version_min");
},
else => {
try argv.append("-iphoneos_version_min");
},
},
else => unreachable,
}
const ver = target.os.version_range.semver.min;
const version_string = try std.fmt.allocPrint(arena, "{d}.{d}.{d}", .{ ver.major, ver.minor, ver.patch });
try argv.append(version_string);
try argv.append("-sdk_version");
try argv.append(version_string);
if (target_util.requiresPIE(target) and self.base.options.output_mode == .Exe) {
try argv.append("-pie");
}
try argv.append("-o");
try argv.append(full_out_path);
// rpaths
var rpath_table = std.StringHashMap(void).init(self.base.allocator);
defer rpath_table.deinit();
for (self.base.options.rpath_list) |rpath| {
if ((try rpath_table.fetchPut(rpath, {})) == null) {
try argv.append("-rpath");
try argv.append(rpath);
}
}
if (is_dyn_lib) {
if ((try rpath_table.fetchPut(full_out_path, {})) == null) {
try argv.append("-rpath");
try argv.append(full_out_path);
}
}
for (self.base.options.lib_dirs) |lib_dir| {
try argv.append("-L");
try argv.append(lib_dir);
}
// Positional arguments to the linker such as object files.
try argv.appendSlice(self.base.options.objects);
for (comp.c_object_table.items()) |entry| {
try argv.append(entry.key.status.success.object_path);
}
if (module_obj_path) |p| {
try argv.append(p);
}
// compiler_rt on darwin is missing some stuff, so we still build it and rely on LinkOnce
if (is_exe_or_dyn_lib and !self.base.options.is_compiler_rt_or_libc) {
try argv.append(comp.compiler_rt_static_lib.?.full_object_path);
}
// Shared libraries.
const system_libs = self.base.options.system_libs.items();
try argv.ensureCapacity(argv.items.len + system_libs.len);
for (system_libs) |entry| {
const link_lib = entry.key;
// By this time, we depend on these libs being dynamically linked libraries and not static libraries
// (the check for that needs to be earlier), but they could be full paths to .dylib files, in which
// case we want to avoid prepending "-l".
const ext = Compilation.classifyFileExt(link_lib);
const arg = if (ext == .shared_library) link_lib else try std.fmt.allocPrint(arena, "-l{}", .{link_lib});
argv.appendAssumeCapacity(arg);
}
// libc++ dep
if (self.base.options.link_libcpp) {
try argv.append(comp.libcxxabi_static_lib.?.full_object_path);
try argv.append(comp.libcxx_static_lib.?.full_object_path);
}
// On Darwin, libSystem has libc in it, but also you have to use it
// to make syscalls because the syscall numbers are not documented
// and change between versions. So we always link against libSystem.
// LLD craps out if you do -lSystem cross compiling, so until that
// codebase gets some love from the new maintainers we're left with
// this dirty hack.
if (self.base.options.is_native_os) {
try argv.append("-lSystem");
}
for (self.base.options.framework_dirs) |framework_dir| {
try argv.append("-F");
try argv.append(framework_dir);
}
for (self.base.options.frameworks) |framework| {
try argv.append("-framework");
try argv.append(framework);
}
if (allow_shlib_undefined) {
try argv.append("-undefined");
try argv.append("dynamic_lookup");
}
if (self.base.options.bind_global_refs_locally) {
try argv.append("-Bsymbolic");
}
if (self.base.options.verbose_link) {
Compilation.dump_argv(argv.items);
}
const new_argv = try arena.allocSentinel(?[*:0]const u8, argv.items.len, null);
for (argv.items) |arg, i| {
new_argv[i] = try arena.dupeZ(u8, arg);
}
var stderr_context: LLDContext = .{
.macho = self,
.data = std.ArrayList(u8).init(self.base.allocator),
};
defer stderr_context.data.deinit();
var stdout_context: LLDContext = .{
.macho = self,
.data = std.ArrayList(u8).init(self.base.allocator),
};
defer stdout_context.data.deinit();
const llvm = @import("../llvm.zig");
const ok = llvm.Link(
.MachO,
new_argv.ptr,
new_argv.len,
append_diagnostic,
@ptrToInt(&stdout_context),
@ptrToInt(&stderr_context),
);
if (stderr_context.oom or stdout_context.oom) return error.OutOfMemory;
if (stdout_context.data.items.len != 0) {
std.log.warn("unexpected LLD stdout: {}", .{stdout_context.data.items});
}
if (!ok) {
// TODO parse this output and surface with the Compilation API rather than
// directly outputting to stderr here.
std.debug.print("{}", .{stderr_context.data.items});
return error.LLDReportedFailure;
}
if (stderr_context.data.items.len != 0) {
std.log.warn("unexpected LLD stderr: {}", .{stderr_context.data.items});
}
}
if (!self.base.options.disable_lld_caching) {
// Update the dangling symlink with the digest. If it fails we can continue; it only
// means that the next invocation will have an unnecessary cache miss.
directory.handle.symLink(&digest, id_symlink_basename, .{}) catch |err| {
std.log.warn("failed to save linking hash digest symlink: {}", .{@errorName(err)});
};
// Again failure here only means an unnecessary cache miss.
man.writeManifest() catch |err| {
std.log.warn("failed to write cache manifest when linking: {}", .{@errorName(err)});
};
// We hang on to this lock so that the output file path can be used without
// other processes clobbering it.
self.base.lock = man.toOwnedLock();
}
}
const LLDContext = struct {
data: std.ArrayList(u8),
macho: *MachO,
oom: bool = false,
};
fn append_diagnostic(context: usize, ptr: [*]const u8, len: usize) callconv(.C) void {
const lld_context = @intToPtr(*LLDContext, context);
const msg = ptr[0..len];
lld_context.data.appendSlice(msg) catch |err| switch (err) {
error.OutOfMemory => lld_context.oom = true,
};
}
fn darwinArchString(arch: std.Target.Cpu.Arch) []const u8 {
return switch (arch) {
.aarch64, .aarch64_be, .aarch64_32 => "arm64",
.thumb, .arm => "arm",
.thumbeb, .armeb => "armeb",
.powerpc => "ppc",
.powerpc64 => "ppc64",
.powerpc64le => "ppc64le",
else => @tagName(arch),
};
}
pub fn deinit(self: *MachO) void {
self.offset_table.deinit(self.base.allocator);
self.string_table.deinit(self.base.allocator);
self.undef_symbols.deinit(self.base.allocator);
self.global_symbols.deinit(self.base.allocator);
self.global_symbol_free_list.deinit(self.base.allocator);
self.local_symbols.deinit(self.base.allocator);
self.sections.deinit(self.base.allocator);
self.load_commands.deinit(self.base.allocator);
}
pub fn allocateDeclIndexes(self: *MachO, decl: *Module.Decl) !void {
if (decl.link.macho.local_sym_index != 0) return;
try self.local_symbols.ensureCapacity(self.base.allocator, self.local_symbols.items.len + 1);
try self.offset_table.ensureCapacity(self.base.allocator, self.offset_table.items.len + 1);
log.debug("allocating symbol index {} for {}\n", .{ self.local_symbols.items.len, decl.name });
decl.link.macho.local_sym_index = @intCast(u32, self.local_symbols.items.len);
_ = self.local_symbols.addOneAssumeCapacity();
decl.link.macho.offset_table_index = @intCast(u32, self.offset_table.items.len);
_ = self.offset_table.addOneAssumeCapacity();
self.local_symbols.items[decl.link.macho.local_sym_index] = .{
.n_strx = 0,
.n_type = 0,
.n_sect = 0,
.n_desc = 0,
.n_value = 0,
};
self.offset_table.items[decl.link.macho.offset_table_index] = 0;
}
pub fn updateDecl(self: *MachO, module: *Module, decl: *Module.Decl) !void {
const tracy = trace(@src());
defer tracy.end();
var code_buffer = std.ArrayList(u8).init(self.base.allocator);
defer code_buffer.deinit();
const typed_value = decl.typed_value.most_recent.typed_value;
const res = try codegen.generateSymbol(&self.base, decl.src(), typed_value, &code_buffer, .none);
const code = switch (res) {
.externally_managed => |x| x,
.appended => code_buffer.items,
.fail => |em| {
decl.analysis = .codegen_failure;
try module.failed_decls.put(module.gpa, decl, em);
return;
},
};
const required_alignment = typed_value.ty.abiAlignment(self.base.options.target);
const symbol = &self.local_symbols.items[decl.link.macho.local_sym_index];
const decl_name = mem.spanZ(decl.name);
const name_str_index = try self.makeString(decl_name);
const addr = try self.allocateTextBlock(&decl.link.macho, code.len, required_alignment);
log.debug("allocated text block for {} at 0x{x}\n", .{ decl_name, addr });
symbol.* = .{
.n_strx = name_str_index,
.n_type = macho.N_SECT,
.n_sect = @intCast(u8, self.text_section_index.?) + 1,
.n_desc = 0,
.n_value = addr,
};
self.offset_table.items[decl.link.macho.offset_table_index] = addr;
try self.writeSymbol(decl.link.macho.local_sym_index);
try self.writeOffsetTableEntry(decl.link.macho.offset_table_index);
const text_section = self.sections.items[self.text_section_index.?];
const section_offset = symbol.n_value - text_section.addr;
const file_offset = text_section.offset + section_offset;
try self.base.file.?.pwriteAll(code, file_offset);
// Since we updated the vaddr and the size, each corresponding export symbol also needs to be updated.
const decl_exports = module.decl_exports.get(decl) orelse &[0]*Module.Export{};
try self.updateDeclExports(module, decl, decl_exports);
}
pub fn updateDeclLineNumber(self: *MachO, module: *Module, decl: *const Module.Decl) !void {}
pub fn updateDeclExports(
self: *MachO,
module: *Module,
decl: *const Module.Decl,
exports: []const *Module.Export,
) !void {
const tracy = trace(@src());
defer tracy.end();
try self.global_symbols.ensureCapacity(self.base.allocator, self.global_symbols.items.len + exports.len);
if (decl.link.macho.local_sym_index == 0) return;
const decl_sym = &self.local_symbols.items[decl.link.macho.local_sym_index];
for (exports) |exp| {
if (exp.options.section) |section_name| {
if (!mem.eql(u8, section_name, "__text")) {
try module.failed_exports.ensureCapacity(module.gpa, module.failed_exports.items().len + 1);
module.failed_exports.putAssumeCapacityNoClobber(
exp,
try Compilation.ErrorMsg.create(self.base.allocator, 0, "Unimplemented: ExportOptions.section", .{}),
);
continue;
}
}
const n_desc = switch (exp.options.linkage) {
.Internal => macho.REFERENCE_FLAG_PRIVATE_DEFINED,
.Strong => blk: {
if (mem.eql(u8, exp.options.name, "_start")) {
self.entry_addr = decl_sym.n_value;
}
break :blk macho.REFERENCE_FLAG_DEFINED;
},
.Weak => macho.N_WEAK_REF,
.LinkOnce => {
try module.failed_exports.ensureCapacity(module.gpa, module.failed_exports.items().len + 1);
module.failed_exports.putAssumeCapacityNoClobber(
exp,
try Compilation.ErrorMsg.create(self.base.allocator, 0, "Unimplemented: GlobalLinkage.LinkOnce", .{}),
);
continue;
},
};
const n_type = decl_sym.n_type | macho.N_EXT;
if (exp.link.macho.sym_index) |i| {
const sym = &self.global_symbols.items[i];
sym.* = .{
.n_strx = try self.updateString(sym.n_strx, exp.options.name),
.n_type = n_type,
.n_sect = @intCast(u8, self.text_section_index.?) + 1,
.n_desc = n_desc,
.n_value = decl_sym.n_value,
};
} else {
const name_str_index = try self.makeString(exp.options.name);
const i = if (self.global_symbol_free_list.popOrNull()) |i| i else blk: {
_ = self.global_symbols.addOneAssumeCapacity();
break :blk self.global_symbols.items.len - 1;
};
self.global_symbols.items[i] = .{
.n_strx = name_str_index,
.n_type = n_type,
.n_sect = @intCast(u8, self.text_section_index.?) + 1,
.n_desc = n_desc,
.n_value = decl_sym.n_value,
};
exp.link.macho.sym_index = @intCast(u32, i);
}
}
}
pub fn deleteExport(self: *MachO, exp: Export) void {
const sym_index = exp.sym_index orelse return;
self.global_symbol_free_list.append(self.base.allocator, sym_index) catch {};
self.global_symbols.items[sym_index].n_type = 0;
}
pub fn freeDecl(self: *MachO, decl: *Module.Decl) void {}
pub fn getDeclVAddr(self: *MachO, decl: *const Module.Decl) u64 {
assert(decl.link.macho.local_sym_index != 0);
return self.local_symbols.items[decl.link.macho.local_sym_index].n_value;
}
pub fn populateMissingMetadata(self: *MachO) !void {
switch (self.base.options.output_mode) {
.Exe => {},
.Obj => return error.TODOImplementWritingObjFiles,
.Lib => return error.TODOImplementWritingLibFiles,
}
if (self.pagezero_segment_cmd_index == null) {
self.pagezero_segment_cmd_index = @intCast(u16, self.load_commands.items.len);
try self.load_commands.append(self.base.allocator, .{
.Segment = .{
.cmd = macho.LC_SEGMENT_64,
.cmdsize = @sizeOf(macho.segment_command_64),
.segname = makeStaticString("__PAGEZERO"),
.vmaddr = 0,
.vmsize = 0x100000000, // size always set to 4GB
.fileoff = 0,
.filesize = 0,
.maxprot = 0,
.initprot = 0,
.nsects = 0,
.flags = 0,
},
});
self.cmd_table_dirty = true;
}
if (self.text_segment_cmd_index == null) {
self.text_segment_cmd_index = @intCast(u16, self.load_commands.items.len);
const prot = macho.VM_PROT_READ | macho.VM_PROT_EXECUTE;
try self.load_commands.append(self.base.allocator, .{
.Segment = .{
.cmd = macho.LC_SEGMENT_64,
.cmdsize = @sizeOf(macho.segment_command_64),
.segname = makeStaticString("__TEXT"),
.vmaddr = 0x100000000, // always starts at 4GB
.vmsize = 0,
.fileoff = 0,
.filesize = 0,
.maxprot = prot,
.initprot = prot,
.nsects = 0,
.flags = 0,
},
});
self.cmd_table_dirty = true;
}
if (self.text_section_index == null) {
self.text_section_index = @intCast(u16, self.sections.items.len);
const text_segment = &self.load_commands.items[self.text_segment_cmd_index.?].Segment;
text_segment.cmdsize += @sizeOf(macho.section_64);
text_segment.nsects += 1;
const file_size = mem.alignForwardGeneric(u64, self.base.options.program_code_size_hint, 0x1000);
const off = @intCast(u32, self.findFreeSpace(file_size, 0x1000)); // TODO maybe findFreeSpace should return u32 directly?
const flags = macho.S_REGULAR | macho.S_ATTR_PURE_INSTRUCTIONS | macho.S_ATTR_SOME_INSTRUCTIONS;
log.debug("found __text section free space 0x{x} to 0x{x}\n", .{ off, off + file_size });
try self.sections.append(self.base.allocator, .{
.sectname = makeStaticString("__text"),
.segname = makeStaticString("__TEXT"),
.addr = text_segment.vmaddr + off,
.size = file_size,
.offset = off,
.@"align" = 12, // 2^12 = 4096
.reloff = 0,
.nreloc = 0,
.flags = flags,
.reserved1 = 0,
.reserved2 = 0,
.reserved3 = 0,
});
text_segment.vmsize = file_size + off; // We add off here since __TEXT segment includes everything prior to __text section.
text_segment.filesize = file_size + off;
}
if (self.data_segment_cmd_index == null) {
self.data_segment_cmd_index = @intCast(u16, self.load_commands.items.len);
const text_segment = &self.load_commands.items[self.text_segment_cmd_index.?].Segment;
const prot = macho.VM_PROT_READ | macho.VM_PROT_WRITE;
try self.load_commands.append(self.base.allocator, .{
.Segment = .{
.cmd = macho.LC_SEGMENT_64,
.cmdsize = @sizeOf(macho.segment_command_64),
.segname = makeStaticString("__DATA"),
.vmaddr = text_segment.vmaddr + text_segment.vmsize,
.vmsize = 0,
.fileoff = 0,
.filesize = 0,
.maxprot = prot,
.initprot = prot,
.nsects = 0,
.flags = 0,
},
});
self.cmd_table_dirty = true;
}
if (self.got_section_index == null) {
self.got_section_index = @intCast(u16, self.sections.items.len);
const data_segment = &self.load_commands.items[self.data_segment_cmd_index.?].Segment;
data_segment.cmdsize += @sizeOf(macho.section_64);
data_segment.nsects += 1;
const file_size = @sizeOf(u64) * self.base.options.symbol_count_hint;
const off = @intCast(u32, self.findFreeSpace(file_size, 0x1000));
log.debug("found __got section free space 0x{x} to 0x{x}\n", .{ off, off + file_size });
try self.sections.append(self.base.allocator, .{
.sectname = makeStaticString("__got"),
.segname = makeStaticString("__DATA"),
.addr = data_segment.vmaddr,