crabc 0.7.7

A Rust musl-compatible libc with a dynamic linker
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// Copyright (c) 2026 Meng Zhuo
// SPDX-License-Identifier: BSD-3-Clause

#![allow(dead_code)]

// Architecture layer for the standalone loader.
//
// Used as a normal module from main.rs.  Contains the raw syscall ABI, the
// active Arch alias, SYS_MMAP and the loader's sys_mmap wrapper.

// ============================================================
// Architecture selection
// ============================================================

// ============================================================
// Syscall ABI
// ============================================================

pub trait Syscalls {
    unsafe fn syscall0(n: i64) -> i64;
    unsafe fn syscall1(n: i64, a1: i64) -> i64;
    unsafe fn syscall2(n: i64, a1: i64, a2: i64) -> i64;
    unsafe fn syscall3(n: i64, a1: i64, a2: i64, a3: i64) -> i64;
    unsafe fn syscall4(n: i64, a1: i64, a2: i64, a3: i64, a4: i64) -> i64;
    unsafe fn syscall5(n: i64, a1: i64, a2: i64, a3: i64, a4: i64, a5: i64) -> i64;
    unsafe fn syscall6(n: i64, a1: i64, a2: i64, a3: i64, a4: i64, a5: i64, a6: i64) -> i64;
    unsafe fn syscall_noreturn1(n: i64, a1: i64) -> !;
}

pub struct X86_64;

// x86_64
#[cfg(target_arch = "x86_64")]
impl Syscalls for X86_64 {
    #[inline]
    unsafe fn syscall0(n: i64) -> i64 {
        let result: i64;
        unsafe {
            core::arch::asm!(
                "syscall",
                inlateout("rax") n => result,
                lateout("rcx") _,
                lateout("r11") _,
            );
        }
        result
    }

    #[inline]
    unsafe fn syscall1(n: i64, a1: i64) -> i64 {
        let result: i64;
        unsafe {
            core::arch::asm!(
                "syscall",
                inlateout("rax") n => result,
                in("rdi") a1,
                lateout("rcx") _,
                lateout("r11") _,
            );
        }
        result
    }

    #[inline]
    unsafe fn syscall2(n: i64, a1: i64, a2: i64) -> i64 {
        let result: i64;
        unsafe {
            core::arch::asm!(
                "syscall",
                inlateout("rax") n => result,
                in("rdi") a1,
                in("rsi") a2,
                lateout("rcx") _,
                lateout("r11") _,
            );
        }
        result
    }

    #[inline]
    unsafe fn syscall3(n: i64, a1: i64, a2: i64, a3: i64) -> i64 {
        let result: i64;
        unsafe {
            core::arch::asm!(
                "syscall",
                inlateout("rax") n => result,
                in("rdi") a1,
                in("rsi") a2,
                in("rdx") a3,
                lateout("rcx") _,
                lateout("r11") _,
            );
        }
        result
    }

    #[inline]
    unsafe fn syscall4(n: i64, a1: i64, a2: i64, a3: i64, a4: i64) -> i64 {
        let result: i64;
        unsafe {
            core::arch::asm!(
                "syscall",
                inlateout("rax") n => result,
                in("rdi") a1,
                in("rsi") a2,
                in("rdx") a3,
                in("r10") a4,
                lateout("rcx") _,
                lateout("r11") _,
            );
        }
        result
    }

    #[inline]
    unsafe fn syscall5(n: i64, a1: i64, a2: i64, a3: i64, a4: i64, a5: i64) -> i64 {
        let result: i64;
        unsafe {
            core::arch::asm!(
                "syscall",
                inlateout("rax") n => result,
                in("rdi") a1,
                in("rsi") a2,
                in("rdx") a3,
                in("r10") a4,
                in("r8") a5,
                lateout("rcx") _,
                lateout("r11") _,
            );
        }
        result
    }

    #[inline]
    unsafe fn syscall6(n: i64, a1: i64, a2: i64, a3: i64, a4: i64, a5: i64, a6: i64) -> i64 {
        let result: i64;
        unsafe {
            core::arch::asm!(
                "syscall",
                inlateout("rax") n => result,
                in("rdi") a1,
                in("rsi") a2,
                in("rdx") a3,
                in("r10") a4,
                in("r8") a5,
                in("r9") a6,
                lateout("rcx") _,
                lateout("r11") _,
            );
        }
        result
    }

    #[inline]
    unsafe fn syscall_noreturn1(n: i64, a1: i64) -> ! {
        unsafe {
            core::arch::asm!(
                "syscall",
                in("rax") n,
                in("rdi") a1,
                options(noreturn)
            );
        }
    }
}

pub struct Aarch64;

// aarch64
#[cfg(target_arch = "aarch64")]
impl Syscalls for Aarch64 {
    #[inline(always)]
    unsafe fn syscall0(n: i64) -> i64 {
        let result: i64;
        core::arch::asm!(
            "svc #0",
            inlateout("x8") n => _,
            lateout("x0") result,
            options(nostack),
        );
        result
    }
    #[inline(always)]
    unsafe fn syscall1(n: i64, a1: i64) -> i64 {
        let result: i64;
        core::arch::asm!(
            "svc #0",
            inlateout("x8") n => _,
            inlateout("x0") a1 => result,
            options(nostack),
        );
        result
    }
    #[inline(always)]
    unsafe fn syscall2(n: i64, a1: i64, a2: i64) -> i64 {
        let result: i64;
        core::arch::asm!(
            "svc #0",
            inlateout("x8") n => _,
            inlateout("x0") a1 => result,
            inlateout("x1") a2 => _,
            options(nostack),
        );
        result
    }
    #[inline(always)]
    unsafe fn syscall3(n: i64, a1: i64, a2: i64, a3: i64) -> i64 {
        let result: i64;
        core::arch::asm!(
            "svc #0",
            inlateout("x8") n => _,
            inlateout("x0") a1 => result,
            inlateout("x1") a2 => _,
            inlateout("x2") a3 => _,
            options(nostack),
        );
        result
    }
    #[inline(always)]
    unsafe fn syscall4(n: i64, a1: i64, a2: i64, a3: i64, a4: i64) -> i64 {
        let result: i64;
        core::arch::asm!(
            "svc #0",
            inlateout("x8") n => _,
            inlateout("x0") a1 => result,
            inlateout("x1") a2 => _,
            inlateout("x2") a3 => _,
            inlateout("x3") a4 => _,
            options(nostack),
        );
        result
    }
    #[inline(always)]
    unsafe fn syscall5(n: i64, a1: i64, a2: i64, a3: i64, a4: i64, a5: i64) -> i64 {
        let result: i64;
        core::arch::asm!(
            "svc #0",
            inlateout("x8") n => _,
            inlateout("x0") a1 => result,
            inlateout("x1") a2 => _,
            inlateout("x2") a3 => _,
            inlateout("x3") a4 => _,
            inlateout("x4") a5 => _,
            options(nostack),
        );
        result
    }
    #[inline(always)]
    unsafe fn syscall6(n: i64, a1: i64, a2: i64, a3: i64, a4: i64, a5: i64, a6: i64) -> i64 {
        let result: i64;
        core::arch::asm!(
            "svc #0",
            inlateout("x8") n => _,
            inlateout("x0") a1 => result,
            inlateout("x1") a2 => _,
            inlateout("x2") a3 => _,
            inlateout("x3") a4 => _,
            inlateout("x4") a5 => _,
            inlateout("x5") a6 => _,
            options(nostack),
        );
        result
    }
    #[inline(always)]
    unsafe fn syscall_noreturn1(n: i64, a1: i64) -> ! {
        core::arch::asm!(
            "svc #0",
            in("x8") n,
            in("x0") a1,
            options(noreturn, nostack),
        );
    }
}

pub struct Riscv64;

// riscv64
#[cfg(target_arch = "riscv64")]
impl Syscalls for Riscv64 {
    #[inline(always)]
    unsafe fn syscall0(n: i64) -> i64 {
        let result: i64;
        core::arch::asm!(
            "ecall",
            inlateout("a7") n => _,
            lateout("a0") result,
            options(nostack),
        );
        result
    }
    #[inline(always)]
    unsafe fn syscall1(n: i64, a1: i64) -> i64 {
        let result: i64;
        core::arch::asm!(
            "ecall",
            inlateout("a7") n => _,
            inlateout("a0") a1 => result,
            options(nostack),
        );
        result
    }
    #[inline(always)]
    unsafe fn syscall2(n: i64, a1: i64, a2: i64) -> i64 {
        let result: i64;
        core::arch::asm!(
            "ecall",
            inlateout("a7") n => _,
            inlateout("a0") a1 => result,
            inlateout("a1") a2 => _,
            options(nostack),
        );
        result
    }
    #[inline(always)]
    unsafe fn syscall3(n: i64, a1: i64, a2: i64, a3: i64) -> i64 {
        let result: i64;
        core::arch::asm!(
            "ecall",
            inlateout("a7") n => _,
            inlateout("a0") a1 => result,
            inlateout("a1") a2 => _,
            inlateout("a2") a3 => _,
            options(nostack),
        );
        result
    }
    #[inline(always)]
    unsafe fn syscall4(n: i64, a1: i64, a2: i64, a3: i64, a4: i64) -> i64 {
        let result: i64;
        core::arch::asm!(
            "ecall",
            inlateout("a7") n => _,
            inlateout("a0") a1 => result,
            inlateout("a1") a2 => _,
            inlateout("a2") a3 => _,
            inlateout("a3") a4 => _,
            options(nostack),
        );
        result
    }
    #[inline(always)]
    unsafe fn syscall5(n: i64, a1: i64, a2: i64, a3: i64, a4: i64, a5: i64) -> i64 {
        let result: i64;
        core::arch::asm!(
            "ecall",
            inlateout("a7") n => _,
            inlateout("a0") a1 => result,
            inlateout("a1") a2 => _,
            inlateout("a2") a3 => _,
            inlateout("a3") a4 => _,
            inlateout("a4") a5 => _,
            options(nostack),
        );
        result
    }
    #[inline(always)]
    unsafe fn syscall6(n: i64, a1: i64, a2: i64, a3: i64, a4: i64, a5: i64, a6: i64) -> i64 {
        let result: i64;
        core::arch::asm!(
            "ecall",
            inlateout("a7") n => _,
            inlateout("a0") a1 => result,
            inlateout("a1") a2 => _,
            inlateout("a2") a3 => _,
            inlateout("a3") a4 => _,
            inlateout("a4") a5 => _,
            inlateout("a5") a6 => _,
            options(nostack),
        );
        result
    }
    #[inline(always)]
    unsafe fn syscall_noreturn1(n: i64, a1: i64) -> ! {
        core::arch::asm!(
            "ecall",
            in("a7") n,
            in("a0") a1,
            options(noreturn, nostack),
        );
    }
}

// ============================================================
// Selected architecture
// ============================================================

// x86_64
#[cfg(target_arch = "x86_64")]
pub type Arch = X86_64;
// aarch64
#[cfg(target_arch = "aarch64")]
pub type Arch = Aarch64;
// riscv64
#[cfg(target_arch = "riscv64")]
pub type Arch = Riscv64;

// ============================================================
// Syscall numbers
// ============================================================

// x86_64
#[cfg(target_arch = "x86_64")]
mod sysnr {
    pub const SYS_MMAP: i64 = 9;
}
// aarch64
#[cfg(target_arch = "aarch64")]
mod sysnr {
    pub const SYS_MMAP: i64 = 222;
}
// riscv64
#[cfg(target_arch = "riscv64")]
mod sysnr {
    pub const SYS_MMAP: i64 = 222;
}
pub use sysnr::*;

// ============================================================
// Syscall wrappers
// ============================================================

/// Drop the loader's own thread pointer before jumping to a static target.
/// The target inherits the address space, and Rust's glibc TLS block is not
/// a crabc TCB: leaving %fs set makes crabc's static startup think TLS is
/// already initialized and skip building its own block.
#[inline]
pub unsafe fn clear_thread_pointer() {
    #[cfg(target_arch = "x86_64")]
    unsafe {
        const SYS_ARCH_PRCTL: i64 = 158;
        const ARCH_SET_FS: i64 = 0x1002;
        let _ = <Arch as Syscalls>::syscall2(SYS_ARCH_PRCTL, ARCH_SET_FS, 0);
    }
    #[cfg(target_arch = "aarch64")]
    unsafe {
        core::arch::asm!("msr tpidr_el0, {}", in(reg) 0usize, options(nostack));
    }
    #[cfg(target_arch = "riscv64")]
    unsafe {
        core::arch::asm!("mv tp, {}", in(reg) 0usize, options(nostack));
    }
}

#[inline]
pub unsafe fn sys_mmap(
    addr: *mut u8,
    length: usize,
    prot: i32,
    flags: i32,
    fd: i32,
    offset: i64,
) -> *mut u8 {
    unsafe {
        <Arch as Syscalls>::syscall6(
            SYS_MMAP,
            addr as i64,
            length as i64,
            prot as i64,
            flags as i64,
            fd as i64,
            offset,
        ) as *mut u8
    }
}