110 lines
3.6 KiB
Zig
110 lines
3.6 KiB
Zig
// This file is in a package which has the root source file exposed as "@root".
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// It is included in the compilation unit when exporting an executable.
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const root = @import("@root");
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const std = @import("std");
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const builtin = @import("builtin");
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var argc_ptr: &usize = undefined;
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comptime {
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const strong_linkage = builtin.GlobalLinkage.Strong;
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if (builtin.link_libc) {
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@export("main", main, strong_linkage);
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} else if (builtin.os == builtin.Os.windows) {
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@export("WinMainCRTStartup", WinMainCRTStartup, strong_linkage);
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} else if (builtin.os == builtin.Os.zen) {
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@export("_start", zen_start, strong_linkage);
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} else {
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@export("_start", _start, strong_linkage);
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}
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}
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extern fn zen_start() noreturn {
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std.os.posix.exit(@inlineCall(callMain));
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}
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nakedcc fn _start() noreturn {
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switch (builtin.arch) {
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builtin.Arch.x86_64 => {
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argc_ptr = asm ("lea (%%rsp), %[argc]" : [argc] "=r" (-> &usize));
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},
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builtin.Arch.i386 => {
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argc_ptr = asm ("lea (%%esp), %[argc]" : [argc] "=r" (-> &usize));
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},
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else => @compileError("unsupported arch"),
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}
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// If LLVM inlines stack variables into _start, they will overwrite
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// the command line argument data.
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@noInlineCall(posixCallMainAndExit);
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}
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extern fn WinMainCRTStartup() noreturn {
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@setAlignStack(16);
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std.os.windows.ExitProcess(callMain());
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}
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fn posixCallMainAndExit() noreturn {
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const argc = argc_ptr.*;
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const argv = @ptrCast(&&u8, &argc_ptr[1]);
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const envp_nullable = @ptrCast(&?&u8, &argv[argc + 1]);
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var envp_count: usize = 0;
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while (envp_nullable[envp_count]) |_| : (envp_count += 1) {}
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const envp = @ptrCast(&&u8, envp_nullable)[0..envp_count];
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if (builtin.os == builtin.Os.linux) {
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const auxv = &@ptrCast(&usize, envp.ptr)[envp_count + 1];
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var i: usize = 0;
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while (auxv[i] != 0) : (i += 2) {
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if (auxv[i] < std.os.linux_aux_raw.len) std.os.linux_aux_raw[auxv[i]] = auxv[i + 1];
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}
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std.debug.assert(std.os.linux_aux_raw[std.elf.AT_PAGESZ] == std.os.page_size);
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}
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std.os.posix.exit(callMainWithArgs(argc, argv, envp));
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}
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fn callMainWithArgs(argc: usize, argv: &&u8, envp: []&u8) u8 {
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std.os.ArgIteratorPosix.raw = argv[0..argc];
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std.os.posix_environ_raw = envp;
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return callMain();
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}
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extern fn main(c_argc: i32, c_argv: &&u8, c_envp: &?&u8) i32 {
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var env_count: usize = 0;
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while (c_envp[env_count] != null) : (env_count += 1) {}
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const envp = @ptrCast(&&u8, c_envp)[0..env_count];
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return callMainWithArgs(usize(c_argc), c_argv, envp);
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}
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fn callMain() u8 {
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switch (@typeId(@typeOf(root.main).ReturnType)) {
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builtin.TypeId.NoReturn => {
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root.main();
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},
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builtin.TypeId.Void => {
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root.main();
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return 0;
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},
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builtin.TypeId.Int => {
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if (@typeOf(root.main).ReturnType.bit_count != 8) {
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@compileError("expected return type of main to be 'u8', 'noreturn', 'void', or '!void'");
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}
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return root.main();
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},
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builtin.TypeId.ErrorUnion => {
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root.main() catch |err| {
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std.debug.warn("error: {}\n", @errorName(err));
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if (builtin.os != builtin.Os.zen) {
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if (@errorReturnTrace()) |trace| {
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std.debug.dumpStackTrace(trace);
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}
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}
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return 1;
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};
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return 0;
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},
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else => @compileError("expected return type of main to be 'u8', 'noreturn', 'void', or '!void'"),
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}
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}
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