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Copy pathc.zig
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674 lines (615 loc) · 20.8 KB
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//! This is Zig's multi-target implementation of libc.
//! When builtin.link_libc is true, we need to export all the functions and
//! provide an entire C API.
//! Otherwise, only the functions which LLVM generates calls to need to be generated,
//! such as memcpy, memset, and some math functions.
const std = @import("std");
const builtin = @import("builtin");
const math = std.math;
const isNan = std.math.isNan;
const maxInt = std.math.maxInt;
const native_os = builtin.os.tag;
const native_arch = builtin.cpu.arch;
const native_abi = builtin.abi;
const is_wasm = switch (native_arch) {
.wasm32, .wasm64 => true,
else => false,
};
const is_msvc = switch (native_abi) {
.msvc => true,
else => false,
};
const is_freestanding = switch (native_os) {
.freestanding => true,
else => false,
};
comptime {
if (is_freestanding and is_wasm and builtin.link_libc) {
@export(wasm_start, .{ .name = "_start", .linkage = .Strong });
}
if (native_os == .linux) {
@export(clone, .{ .name = "clone" });
}
@export(memset, .{ .name = "memset", .linkage = .Strong });
@export(__memset, .{ .name = "__memset", .linkage = .Strong });
@export(memcpy, .{ .name = "memcpy", .linkage = .Strong });
@export(memmove, .{ .name = "memmove", .linkage = .Strong });
@export(memcmp, .{ .name = "memcmp", .linkage = .Strong });
@export(bcmp, .{ .name = "bcmp", .linkage = .Strong });
if (builtin.link_libc) {
@export(strcmp, .{ .name = "strcmp", .linkage = .Strong });
@export(strncmp, .{ .name = "strncmp", .linkage = .Strong });
@export(strerror, .{ .name = "strerror", .linkage = .Strong });
@export(strlen, .{ .name = "strlen", .linkage = .Strong });
@export(strcpy, .{ .name = "strcpy", .linkage = .Strong });
@export(strncpy, .{ .name = "strncpy", .linkage = .Strong });
@export(strcat, .{ .name = "strcat", .linkage = .Strong });
@export(strncat, .{ .name = "strncat", .linkage = .Strong });
} else if (is_msvc) {
@export(_fltused, .{ .name = "_fltused", .linkage = .Strong });
}
}
// Avoid dragging in the runtime safety mechanisms into this .o file,
// unless we're trying to test this file.
pub fn panic(msg: []const u8, error_return_trace: ?*std.builtin.StackTrace) noreturn {
@setCold(true);
_ = error_return_trace;
if (builtin.is_test) {
std.debug.panic("{s}", .{msg});
}
if (native_os != .freestanding and native_os != .other) {
std.os.abort();
}
while (true) {}
}
extern fn main(argc: c_int, argv: [*:null]?[*:0]u8) c_int;
fn wasm_start() callconv(.C) void {
_ = main(0, undefined);
}
fn memset(dest: ?[*]u8, c: u8, len: usize) callconv(.C) ?[*]u8 {
@setRuntimeSafety(false);
if (len != 0) {
var d = dest.?;
var n = len;
while (true) {
d.* = c;
n -= 1;
if (n == 0) break;
d += 1;
}
}
return dest;
}
fn __memset(dest: ?[*]u8, c: u8, n: usize, dest_n: usize) callconv(.C) ?[*]u8 {
if (dest_n < n)
@panic("buffer overflow");
return memset(dest, c, n);
}
fn memcpy(noalias dest: ?[*]u8, noalias src: ?[*]const u8, len: usize) callconv(.C) ?[*]u8 {
@setRuntimeSafety(false);
if (len != 0) {
var d = dest.?;
var s = src.?;
var n = len;
while (true) {
d[0] = s[0];
n -= 1;
if (n == 0) break;
d += 1;
s += 1;
}
}
return dest;
}
fn memmove(dest: ?[*]u8, src: ?[*]const u8, n: usize) callconv(.C) ?[*]u8 {
@setRuntimeSafety(false);
if (@ptrToInt(dest) < @ptrToInt(src)) {
var index: usize = 0;
while (index != n) : (index += 1) {
dest.?[index] = src.?[index];
}
} else {
var index = n;
while (index != 0) {
index -= 1;
dest.?[index] = src.?[index];
}
}
return dest;
}
fn memcmp(vl: ?[*]const u8, vr: ?[*]const u8, n: usize) callconv(.C) c_int {
@setRuntimeSafety(false);
var index: usize = 0;
while (index != n) : (index += 1) {
const compare_val = @bitCast(i8, vl.?[index] -% vr.?[index]);
if (compare_val != 0) {
return compare_val;
}
}
return 0;
}
test "memcmp" {
const base_arr = &[_]u8{ 1, 1, 1 };
const arr1 = &[_]u8{ 1, 1, 1 };
const arr2 = &[_]u8{ 1, 0, 1 };
const arr3 = &[_]u8{ 1, 2, 1 };
try std.testing.expect(memcmp(base_arr[0..], arr1[0..], base_arr.len) == 0);
try std.testing.expect(memcmp(base_arr[0..], arr2[0..], base_arr.len) > 0);
try std.testing.expect(memcmp(base_arr[0..], arr3[0..], base_arr.len) < 0);
}
fn bcmp(vl: [*]allowzero const u8, vr: [*]allowzero const u8, n: usize) callconv(.C) c_int {
@setRuntimeSafety(false);
var index: usize = 0;
while (index != n) : (index += 1) {
if (vl[index] != vr[index]) {
return 1;
}
}
return 0;
}
test "bcmp" {
const base_arr = &[_]u8{ 1, 1, 1 };
const arr1 = &[_]u8{ 1, 1, 1 };
const arr2 = &[_]u8{ 1, 0, 1 };
const arr3 = &[_]u8{ 1, 2, 1 };
try std.testing.expect(bcmp(base_arr[0..], arr1[0..], base_arr.len) == 0);
try std.testing.expect(bcmp(base_arr[0..], arr2[0..], base_arr.len) != 0);
try std.testing.expect(bcmp(base_arr[0..], arr3[0..], base_arr.len) != 0);
}
var _fltused: c_int = 1;
fn strcpy(dest: [*:0]u8, src: [*:0]const u8) callconv(.C) [*:0]u8 {
var i: usize = 0;
while (src[i] != 0) : (i += 1) {
dest[i] = src[i];
}
dest[i] = 0;
return dest;
}
test "strcpy" {
var s1: [9:0]u8 = undefined;
s1[0] = 0;
_ = strcpy(&s1, "foobarbaz");
try std.testing.expectEqualSlices(u8, "foobarbaz", std.mem.sliceTo(&s1, 0));
}
fn strncpy(dest: [*:0]u8, src: [*:0]const u8, n: usize) callconv(.C) [*:0]u8 {
var i: usize = 0;
while (i < n and src[i] != 0) : (i += 1) {
dest[i] = src[i];
}
while (i < n) : (i += 1) {
dest[i] = 0;
}
return dest;
}
test "strncpy" {
var s1: [9:0]u8 = undefined;
s1[0] = 0;
_ = strncpy(&s1, "foobarbaz", @sizeOf(@TypeOf(s1)));
try std.testing.expectEqualSlices(u8, "foobarbaz", std.mem.sliceTo(&s1, 0));
}
fn strcat(dest: [*:0]u8, src: [*:0]const u8) callconv(.C) [*:0]u8 {
var dest_end: usize = 0;
while (dest[dest_end] != 0) : (dest_end += 1) {}
var i: usize = 0;
while (src[i] != 0) : (i += 1) {
dest[dest_end + i] = src[i];
}
dest[dest_end + i] = 0;
return dest;
}
test "strcat" {
var s1: [9:0]u8 = undefined;
s1[0] = 0;
_ = strcat(&s1, "foo");
_ = strcat(&s1, "bar");
_ = strcat(&s1, "baz");
try std.testing.expectEqualSlices(u8, "foobarbaz", std.mem.sliceTo(&s1, 0));
}
fn strncat(dest: [*:0]u8, src: [*:0]const u8, avail: usize) callconv(.C) [*:0]u8 {
var dest_end: usize = 0;
while (dest[dest_end] != 0) : (dest_end += 1) {}
var i: usize = 0;
while (i < avail and src[i] != 0) : (i += 1) {
dest[dest_end + i] = src[i];
}
dest[dest_end + i] = 0;
return dest;
}
test "strncat" {
var s1: [9:0]u8 = undefined;
s1[0] = 0;
_ = strncat(&s1, "foo1111", 3);
_ = strncat(&s1, "bar1111", 3);
_ = strncat(&s1, "baz1111", 3);
try std.testing.expectEqualSlices(u8, "foobarbaz", std.mem.sliceTo(&s1, 0));
}
fn strcmp(s1: [*:0]const u8, s2: [*:0]const u8) callconv(.C) c_int {
return std.cstr.cmp(s1, s2);
}
fn strlen(s: [*:0]const u8) callconv(.C) usize {
return std.mem.len(s);
}
fn strncmp(_l: [*:0]const u8, _r: [*:0]const u8, _n: usize) callconv(.C) c_int {
if (_n == 0) return 0;
var l = _l;
var r = _r;
var n = _n - 1;
while (l[0] != 0 and r[0] != 0 and n != 0 and l[0] == r[0]) {
l += 1;
r += 1;
n -= 1;
}
return @as(c_int, l[0]) - @as(c_int, r[0]);
}
fn strerror(errnum: c_int) callconv(.C) [*:0]const u8 {
_ = errnum;
return "TODO strerror implementation";
}
test "strncmp" {
try std.testing.expect(strncmp("a", "b", 1) == -1);
try std.testing.expect(strncmp("a", "c", 1) == -2);
try std.testing.expect(strncmp("b", "a", 1) == 1);
try std.testing.expect(strncmp("\xff", "\x02", 1) == 253);
}
// TODO we should be able to put this directly in std/linux/x86_64.zig but
// it causes a segfault in release mode. this is a workaround of calling it
// across .o file boundaries. fix comptime @ptrCast of nakedcc functions.
fn clone() callconv(.Naked) void {
switch (native_arch) {
.i386 => {
// __clone(func, stack, flags, arg, ptid, tls, ctid)
// +8, +12, +16, +20, +24, +28, +32
// syscall(SYS_clone, flags, stack, ptid, tls, ctid)
// eax, ebx, ecx, edx, esi, edi
asm volatile (
\\ push %%ebp
\\ mov %%esp,%%ebp
\\ push %%ebx
\\ push %%esi
\\ push %%edi
\\ // Setup the arguments
\\ mov 16(%%ebp),%%ebx
\\ mov 12(%%ebp),%%ecx
\\ and $-16,%%ecx
\\ sub $20,%%ecx
\\ mov 20(%%ebp),%%eax
\\ mov %%eax,4(%%ecx)
\\ mov 8(%%ebp),%%eax
\\ mov %%eax,0(%%ecx)
\\ mov 24(%%ebp),%%edx
\\ mov 28(%%ebp),%%esi
\\ mov 32(%%ebp),%%edi
\\ mov $120,%%eax
\\ int $128
\\ test %%eax,%%eax
\\ jnz 1f
\\ pop %%eax
\\ xor %%ebp,%%ebp
\\ call *%%eax
\\ mov %%eax,%%ebx
\\ xor %%eax,%%eax
\\ inc %%eax
\\ int $128
\\ hlt
\\1:
\\ pop %%edi
\\ pop %%esi
\\ pop %%ebx
\\ pop %%ebp
\\ ret
);
},
.x86_64 => {
asm volatile (
\\ xor %%eax,%%eax
\\ mov $56,%%al // SYS_clone
\\ mov %%rdi,%%r11
\\ mov %%rdx,%%rdi
\\ mov %%r8,%%rdx
\\ mov %%r9,%%r8
\\ mov 8(%%rsp),%%r10
\\ mov %%r11,%%r9
\\ and $-16,%%rsi
\\ sub $8,%%rsi
\\ mov %%rcx,(%%rsi)
\\ syscall
\\ test %%eax,%%eax
\\ jnz 1f
\\ xor %%ebp,%%ebp
\\ pop %%rdi
\\ call *%%r9
\\ mov %%eax,%%edi
\\ xor %%eax,%%eax
\\ mov $60,%%al // SYS_exit
\\ syscall
\\ hlt
\\1: ret
\\
);
},
.aarch64 => {
// __clone(func, stack, flags, arg, ptid, tls, ctid)
// x0, x1, w2, x3, x4, x5, x6
// syscall(SYS_clone, flags, stack, ptid, tls, ctid)
// x8, x0, x1, x2, x3, x4
asm volatile (
\\ // align stack and save func,arg
\\ and x1,x1,#-16
\\ stp x0,x3,[x1,#-16]!
\\
\\ // syscall
\\ uxtw x0,w2
\\ mov x2,x4
\\ mov x3,x5
\\ mov x4,x6
\\ mov x8,#220 // SYS_clone
\\ svc #0
\\
\\ cbz x0,1f
\\ // parent
\\ ret
\\ // child
\\1: ldp x1,x0,[sp],#16
\\ blr x1
\\ mov x8,#93 // SYS_exit
\\ svc #0
);
},
.arm, .thumb => {
// __clone(func, stack, flags, arg, ptid, tls, ctid)
// r0, r1, r2, r3, +0, +4, +8
// syscall(SYS_clone, flags, stack, ptid, tls, ctid)
// r7 r0, r1, r2, r3, r4
asm volatile (
\\ stmfd sp!,{r4,r5,r6,r7}
\\ mov r7,#120
\\ mov r6,r3
\\ mov r5,r0
\\ mov r0,r2
\\ and r1,r1,#-16
\\ ldr r2,[sp,#16]
\\ ldr r3,[sp,#20]
\\ ldr r4,[sp,#24]
\\ svc 0
\\ tst r0,r0
8000
\\ beq 1f
\\ ldmfd sp!,{r4,r5,r6,r7}
\\ bx lr
\\
\\1: mov r0,r6
\\ bl 3f
\\2: mov r7,#1
\\ svc 0
\\ b 2b
\\3: bx r5
);
},
.riscv64 => {
// __clone(func, stack, flags, arg, ptid, tls, ctid)
// a0, a1, a2, a3, a4, a5, a6
// syscall(SYS_clone, flags, stack, ptid, tls, ctid)
// a7 a0, a1, a2, a3, a4
asm volatile (
\\ # Save func and arg to stack
\\ addi a1, a1, -16
\\ sd a0, 0(a1)
\\ sd a3, 8(a1)
\\
\\ # Call SYS_clone
\\ mv a0, a2
\\ mv a2, a4
\\ mv a3, a5
\\ mv a4, a6
\\ li a7, 220 # SYS_clone
\\ ecall
\\
\\ beqz a0, 1f
\\ # Parent
\\ ret
\\
\\ # Child
\\1: ld a1, 0(sp)
\\ ld a0, 8(sp)
\\ jalr a1
\\
\\ # Exit
\\ li a7, 93 # SYS_exit
\\ ecall
);
},
.mips, .mipsel => {
// __clone(func, stack, flags, arg, ptid, tls, ctid)
// 3, 4, 5, 6, 7, 8, 9
// syscall(SYS_clone, flags, stack, ptid, tls, ctid)
// 2 4, 5, 6, 7, 8
asm volatile (
\\ # Save function pointer and argument pointer on new thread stack
\\ and $5, $5, -8
\\ subu $5, $5, 16
\\ sw $4, 0($5)
\\ sw $7, 4($5)
\\ # Shuffle (fn,sp,fl,arg,ptid,tls,ctid) to (fl,sp,ptid,tls,ctid)
\\ move $4, $6
\\ lw $6, 16($sp)
\\ lw $7, 20($sp)
\\ lw $9, 24($sp)
\\ subu $sp, $sp, 16
\\ sw $9, 16($sp)
\\ li $2, 4120
\\ syscall
\\ beq $7, $0, 1f
\\ nop
\\ addu $sp, $sp, 16
\\ jr $ra
\\ subu $2, $0, $2
\\1:
\\ beq $2, $0, 1f
\\ nop
\\ addu $sp, $sp, 16
\\ jr $ra
\\ nop
\\1:
\\ lw $25, 0($sp)
\\ lw $4, 4($sp)
\\ jalr $25
\\ nop
\\ move $4, $2
\\ li $2, 4001
\\ syscall
);
},
.powerpc => {
// __clone(func, stack, flags, arg, ptid, tls, ctid)
// 3, 4, 5, 6, 7, 8, 9
// syscall(SYS_clone, flags, stack, ptid, tls, ctid)
// 0 3, 4, 5, 6, 7
asm volatile (
\\# store non-volatile regs r30, r31 on stack in order to put our
\\# start func and its arg there
\\stwu 30, -16(1)
\\stw 31, 4(1)
\\
\\# save r3 (func) into r30, and r6(arg) into r31
\\mr 30, 3
\\mr 31, 6
\\
\\# create initial stack frame for new thread
\\clrrwi 4, 4, 4
\\li 0, 0
\\stwu 0, -16(4)
\\
\\#move c into first arg
\\mr 3, 5
\\#mr 4, 4
\\mr 5, 7
\\mr 6, 8
\\mr 7, 9
\\
\\# move syscall number into r0
\\li 0, 120
\\
\\sc
\\
\\# check for syscall error
\\bns+ 1f # jump to label 1 if no summary overflow.
\\#else
\\neg 3, 3 #negate the result (errno)
\\1:
\\# compare sc result with 0
\\cmpwi cr7, 3, 0
\\
\\# if not 0, jump to end
\\bne cr7, 2f
\\
\\#else: we're the child
\\#call funcptr: move arg (d) into r3
\\mr 3, 31
\\#move r30 (funcptr) into CTR reg
\\mtctr 30
\\# call CTR reg
\\bctrl
\\# mov SYS_exit into r0 (the exit param is already in r3)
\\li 0, 1
\\sc
\\
\\2:
\\
\\# restore stack
\\lwz 30, 0(1)
\\lwz 31, 4(1)
\\addi 1, 1, 16
\\
\\blr
);
},
.powerpc64, .powerpc64le => {
// __clone(func, stack, flags, arg, ptid, tls, ctid)
// 3, 4, 5, 6, 7, 8, 9
// syscall(SYS_clone, flags, stack, ptid, tls, ctid)
// 0 3, 4, 5, 6, 7
asm volatile (
\\ # create initial stack frame for new thread
\\ clrrdi 4, 4, 4
\\ li 0, 0
\\ stdu 0,-32(4)
\\
\\ # save fn and arg to child stack
\\ std 3, 8(4)
\\ std 6, 16(4)
\\
\\ # shuffle args into correct registers and call SYS_clone
\\ mr 3, 5
\\ #mr 4, 4
\\ mr 5, 7
\\ mr 6, 8
\\ mr 7, 9
\\ li 0, 120 # SYS_clone = 120
\\ sc
\\
\\ # if error, negate return (errno)
\\ bns+ 1f
\\ neg 3, 3
\\
\\1:
\\ # if we're the parent, return
\\ cmpwi cr7, 3, 0
\\ bnelr cr7
\\
\\ # we're the child. call fn(arg)
\\ ld 3, 16(1)
\\ ld 12, 8(1)
\\ mtctr 12
\\ bctrl
\\
\\ # call SYS_exit. exit code is already in r3 from fn return value
\\ li 0, 1 # SYS_exit = 1
\\ sc
);
},
.sparc64 => {
// __clone(func, stack, flags, arg, ptid, tls, ctid)
// i0, i1, i2, i3, i4, i5, sp
// syscall(SYS_clone, flags, stack, ptid, tls, ctid)
// g1 o0, o1, o2, o3, o4
asm volatile (
\\ save %%sp, -192, %%sp
\\ # Save the func pointer and the arg pointer
\\ mov %%i0, %%g2
\\ mov %%i3, %%g3
\\ # Shuffle the arguments
\\ mov 217, %%g1
\\ mov %%i2, %%o0
\\ # Add some extra space for the initial frame
\\ sub %%i1, 176 + 2047, %%o1
\\ mov %%i4, %%o2
\\ mov %%i5, %%o3
\\ ldx [%%fp + 0x8af], %%o4
\\ t 0x6d
\\ bcs,pn %%xcc, 2f
\\ nop
\\ # The child pid is returned in o0 while o1 tells if this
\\ # process is # the child (=1) or the parent (=0).
\\ brnz %%o1, 1f
\\ nop
\\ # Parent process, return the child pid
\\ mov %%o0, %%i0
\\ ret
\\ restore
\\1:
\\ # Child process, call func(arg)
\\ mov %%g0, %%fp
\\ call %%g2
\\ mov %%g3, %%o0
\\ # Exit
\\ mov 1, %%g1
\\ t 0x6d
\\2:
\\ # The syscall failed
\\ sub %%g0, %%o0, %%i0
\\ ret
\\ restore
);
},
else => @compileError("Implement clone() for this arch."),
}
}