rumpk/libs/membrane/libc_shim.zig

137 lines
3.5 KiB
Zig

const std = @import("std");
// --- 1. IO PRIMITIVES ---
// We import 'write' and 'exit' from libc.nim / clib.c (found in libnexus.a)
extern fn write(fd: i32, buf: [*]const u8, count: usize) isize;
extern fn exit(status: i32) noreturn;
export fn fputc(c: i32, stream: ?*anyopaque) i32 {
_ = stream;
const char = @as(u8, @intCast(c));
const buf = [1]u8{char};
_ = write(1, &buf, 1);
return c;
}
export fn fputs(s: [*]const u8, stream: ?*anyopaque) i32 {
_ = stream;
var len: usize = 0;
while (s[len] != 0) : (len += 1) {}
_ = write(1, s, len);
return 1;
}
// --- 2. THE MISSING SYMBOLS (STUBS) ---
// Nim checks for errors on streams. We say "No error".
export fn ferror(stream: ?*anyopaque) i32 {
_ = stream;
return 0;
}
export fn clearerr(stream: ?*anyopaque) void {
_ = stream;
}
// Nim looks for chars in memory (optimized scans).
export fn memchr(s: ?*const anyopaque, c: i32, n: usize) ?*anyopaque {
if (s) |src_ptr| {
const src: [*]const u8 = @ptrCast(src_ptr);
const target = @as(u8, @intCast(c));
var i: usize = 0;
while (i < n) : (i += 1) {
if (src[i] == target) return @ptrCast(@constCast(src + i));
}
}
return null;
}
extern fn ion_user_free(pkt: ion.IonPacket) void;
export fn read(fd: i32, buf: [*]u8, count: usize) isize {
if (fd != 0) return -1;
var pkt: ion.IonPacket = undefined;
while (!ion.sys_input_pop(&pkt)) {
nexus_yield();
}
const to_copy = @min(count, pkt.len);
const src = @as([*]const u8, @ptrFromInt(pkt.data));
@memcpy(buf[0..to_copy], src[0..to_copy]);
ion_user_free(pkt);
return @intCast(to_copy);
}
// Nim tries to read lines.
export fn fgets(s: [*]u8, size: i32, stream: ?*anyopaque) ?[*]u8 {
_ = stream;
if (size <= 0) return null;
var pkt: ion.IonPacket = undefined;
while (!ion.sys_input_pop(&pkt)) {
nexus_yield();
}
const to_copy = @min(@as(usize, @intCast(size - 1)), pkt.len);
const src = @as([*]const u8, @ptrFromInt(pkt.data));
@memcpy(s[0..to_copy], src[0..to_copy]);
s[to_copy] = 0;
ion_user_free(pkt);
return s;
}
export fn fgetc(stream: ?*anyopaque) i32 {
_ = stream;
var c: u8 = undefined;
const n = read(0, @ptrCast(&c), 1);
if (n <= 0) return -1;
return @intCast(c);
}
// Math stubs (sometimes needed)
export fn dlopen() void {}
export fn dlsym() void {}
export fn strerror(errnum: i32) [*]const u8 {
_ = errnum;
return "Unknown Error";
}
extern fn main(argc: i32, argv: [*]const [*]const u8) i32;
// _start relocated to subject_entry.S
const ion = @import("ion.zig");
// Sovereign Syscall: Push to CMD Ring
export fn nexus_syscall(cmd_id: u32, arg: u32) c_int {
// Construct Packet
var pkt = ion.CmdPacket{ .kind = cmd_id, .arg = arg, .id = [_]u8{0} ** 16 };
// Compute Provenance (SipHash)
const key = "\xde\xad\xbe\xef\xca\xfe\xba\xbe\x00\x01\x02\x03\x04\x05\x06\x07";
var hasher = std.crypto.auth.siphash.SipHash128(1, 3).init(key);
hasher.update(std.mem.asBytes(&pkt.kind));
hasher.update(std.mem.asBytes(&pkt.arg));
const hash_int = hasher.finalInt();
pkt.id = std.mem.toBytes(hash_int);
// Push to High-Priority CMD Ring
if (!ion.sys_cmd_push(pkt)) {
return -1; // Error: Ring full/backpressure
}
return 0; // Success
}
// Sovereign Yield: Return control to Kernel Scheduler
export fn nexus_yield() void {
const yield_ptr = @as(*const *const fn () void, @ptrFromInt(0x83000FF0));
yield_ptr.*();
}