zig/std/special/bootstrap.zig
2017-12-19 02:39:43 -05:00

65 lines
1.9 KiB
Zig

// This file is in a package which has the root source file exposed as "@root".
// It is included in the compilation unit when exporting an executable.
const root = @import("@root");
const std = @import("std");
const builtin = @import("builtin");
var argc_ptr: &usize = undefined;
comptime {
const strong_linkage = builtin.GlobalLinkage.Strong;
if (builtin.link_libc) {
@export("main", main, strong_linkage);
} else if (builtin.os == builtin.Os.windows) {
@export("WinMainCRTStartup", WinMainCRTStartup, strong_linkage);
} else {
@export("_start", _start, strong_linkage);
}
}
nakedcc fn _start() -> noreturn {
switch (builtin.arch) {
builtin.Arch.x86_64 => {
argc_ptr = asm("lea (%%rsp), %[argc]": [argc] "=r" (-> &usize));
},
builtin.Arch.i386 => {
argc_ptr = asm("lea (%%esp), %[argc]": [argc] "=r" (-> &usize));
},
else => @compileError("unsupported arch"),
}
// If LLVM inlines stack variables into _start, they will overwrite
// the command line argument data.
@noInlineCall(posixCallMainAndExit);
}
extern fn WinMainCRTStartup() -> noreturn {
@setAlignStack(16);
root.main() %% std.os.windows.ExitProcess(1);
std.os.windows.ExitProcess(0);
}
fn posixCallMainAndExit() -> noreturn {
const argc = *argc_ptr;
const argv = @ptrCast(&&u8, &argc_ptr[1]);
const envp = @ptrCast(&?&u8, &argv[argc + 1]);
callMain(argc, argv, envp) %% std.os.posix.exit(1);
std.os.posix.exit(0);
}
fn callMain(argc: usize, argv: &&u8, envp: &?&u8) -> %void {
std.os.ArgIteratorPosix.raw = argv[0..argc];
var env_count: usize = 0;
while (envp[env_count] != null) : (env_count += 1) {}
std.os.posix_environ_raw = @ptrCast(&&u8, envp)[0..env_count];
return root.main();
}
extern fn main(c_argc: i32, c_argv: &&u8, c_envp: &?&u8) -> i32 {
callMain(usize(c_argc), c_argv, c_envp) %% return 1;
return 0;
}