sleep
Owner: IIIlllIIIllI URL: git@github.com:nyangkosense/sleep.git
init
Commit be2f6f447a21bdbaea004b3c61e270333cb5d0ea by IIIlllIIIllI <seb.michalk@gmail.com> on 2025-12-14 09:40:34 +0100
diff --git a/build.zig b/build.zig
new file mode 100644
index 0000000..64012ac
--- /dev/null
+++ b/build.zig
@@ -0,0 +1,116 @@
+const std = @import("std");
+
+// Although this function looks imperative, note that its job is to
+// declaratively construct a build graph that will be executed by an external
+// runner.
+pub fn build(b: *std.Build) void {
+ // Standard target options allows the person running `zig build` to choose
+ // what target to build for. Here we do not override the defaults, which
+ // means any target is allowed, and the default is native. Other options
+ // for restricting supported target set are available.
+ const target = b.standardTargetOptions(.{});
+
+ // Standard optimization options allow the person running `zig build` to select
+ // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
+ // set a preferred release mode, allowing the user to decide how to optimize.
+ const optimize = b.standardOptimizeOption(.{});
+
+ // This creates a "module", which represents a collection of source files alongside
+ // some compilation options, such as optimization mode and linked system libraries.
+ // Every executable or library we compile will be based on one or more modules.
+ const lib_mod = b.createModule(.{
+ // `root_source_file` is the Zig "entry point" of the module. If a module
+ // only contains e.g. external object files, you can make this `null`.
+ // In this case the main source file is merely a path, however, in more
+ // complicated build scripts, this could be a generated file.
+ .root_source_file = b.path("sleep.zig"),
+ .target = target,
+ .optimize = optimize,
+ });
+
+ // We will also create a module for our other entry point, 'main.zig'.
+ const exe_mod = b.createModule(.{
+ // `root_source_file` is the Zig "entry point" of the module. If a module
+ // only contains e.g. external object files, you can make this `null`.
+ // In this case the main source file is merely a path, however, in more
+ // complicated build scripts, this could be a generated file.
+ .root_source_file = b.path("sleep.zig"),
+ .target = target,
+ .optimize = optimize,
+ });
+
+ // Modules can depend on one another using the `std.Build.Module.addImport` function.
+ // This is what allows Zig source code to use `@import("foo")` where 'foo' is not a
+ // file path. In this case, we set up `exe_mod` to import `lib_mod`.
+ exe_mod.addImport("sleep_lib", lib_mod);
+
+ // Now, we will create a static library based on the module we created above.
+ // This creates a `std.Build.Step.Compile`, which is the build step responsible
+ // for actually invoking the compiler.
+ const lib = b.addLibrary(.{
+ .linkage = .static,
+ .name = "sleep",
+ .root_module = lib_mod,
+ });
+
+ // This declares intent for the library to be installed into the standard
+ // location when the user invokes the "install" step (the default step when
+ // running `zig build`).
+ b.installArtifact(lib);
+
+ // This creates another `std.Build.Step.Compile`, but this one builds an executable
+ // rather than a static library.
+ const exe = b.addExecutable(.{
+ .name = "sleep",
+ .root_module = exe_mod,
+ });
+
+ // This declares intent for the executable to be installed into the
+ // standard location when the user invokes the "install" step (the default
+ // step when running `zig build`).
+ b.installArtifact(exe);
+
+ // This *creates* a Run step in the build graph, to be executed when another
+ // step is evaluated that depends on it. The next line below will establish
+ // such a dependency.
+ const run_cmd = b.addRunArtifact(exe);
+
+ // By making the run step depend on the install step, it will be run from the
+ // installation directory rather than directly from within the cache directory.
+ // This is not necessary, however, if the application depends on other installed
+ // files, this ensures they will be present and in the expected location.
+ run_cmd.step.dependOn(b.getInstallStep());
+
+ // This allows the user to pass arguments to the application in the build
+ // command itself, like this: `zig build run -- arg1 arg2 etc`
+ if (b.args) |args| {
+ run_cmd.addArgs(args);
+ }
+
+ // This creates a build step. It will be visible in the `zig build --help` menu,
+ // and can be selected like this: `zig build run`
+ // This will evaluate the `run` step rather than the default, which is "install".
+ const run_step = b.step("run", "Run the app");
+ run_step.dependOn(&run_cmd.step);
+
+ // Creates a step for unit testing. This only builds the test executable
+ // but does not run it.
+ const lib_unit_tests = b.addTest(.{
+ .root_module = lib_mod,
+ });
+
+ const run_lib_unit_tests = b.addRunArtifact(lib_unit_tests);
+
+ const exe_unit_tests = b.addTest(.{
+ .root_module = exe_mod,
+ });
+
+ const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);
+
+ // Similar to creating the run step earlier, this exposes a `test` step to
+ // the `zig build --help` menu, providing a way for the user to request
+ // running the unit tests.
+ const test_step = b.step("test", "Run unit tests");
+ test_step.dependOn(&run_lib_unit_tests.step);
+ test_step.dependOn(&run_exe_unit_tests.step);
+}
diff --git a/build.zig.zon b/build.zig.zon
new file mode 100644
index 0000000..dcbcfc9
--- /dev/null
+++ b/build.zig.zon
@@ -0,0 +1,86 @@
+.{
+ // This is the default name used by packages depending on this one. For
+ // example, when a user runs `zig fetch --save <url>`, this field is used
+ // as the key in the `dependencies` table. Although the user can choose a
+ // different name, most users will stick with this provided value.
+ //
+ // It is redundant to include "zig" in this name because it is already
+ // within the Zig package namespace.
+ .name = .sleep,
+
+ // This is a [Semantic Version](https://semver.org/).
+ // In a future version of Zig it will be used for package deduplication.
+ .version = "0.0.0",
+
+ // Together with name, this represents a globally unique package
+ // identifier. This field is generated by the Zig toolchain when the
+ // package is first created, and then *never changes*. This allows
+ // unambiguous detection of one package being an updated version of
+ // another.
+ //
+ // When forking a Zig project, this id should be regenerated (delete the
+ // field and run `zig build`) if the upstream project is still maintained.
+ // Otherwise, the fork is *hostile*, attempting to take control over the
+ // original project's identity. Thus it is recommended to leave the comment
+ // on the following line intact, so that it shows up in code reviews that
+ // modify the field.
+ .fingerprint = 0xf33c2ac7aa3b32d, // Changing this has security and trust implications.
+
+ // Tracks the earliest Zig version that the package considers to be a
+ // supported use case.
+ .minimum_zig_version = "0.14.0",
+
+ // This field is optional.
+ // Each dependency must either provide a `url` and `hash`, or a `path`.
+ // `zig build --fetch` can be used to fetch all dependencies of a package, recursively.
+ // Once all dependencies are fetched, `zig build` no longer requires
+ // internet connectivity.
+ .dependencies = .{
+ // See `zig fetch --save <url>` for a command-line interface for adding dependencies.
+ //.example = .{
+ // // When updating this field to a new URL, be sure to delete the corresponding
+ // // `hash`, otherwise you are communicating that you expect to find the old hash at
+ // // the new URL. If the contents of a URL change this will result in a hash mismatch
+ // // which will prevent zig from using it.
+ // .url = "https://example.com/foo.tar.gz",
+ //
+ // // This is computed from the file contents of the directory of files that is
+ // // obtained after fetching `url` and applying the inclusion rules given by
+ // // `paths`.
+ // //
+ // // This field is the source of truth; packages do not come from a `url`; they
+ // // come from a `hash`. `url` is just one of many possible mirrors for how to
+ // // obtain a package matching this `hash`.
+ // //
+ // // Uses the [multihash](https://multiformats.io/multihash/) format.
+ // .hash = "...",
+ //
+ // // When this is provided, the package is found in a directory relative to the
+ // // build root. In this case the package's hash is irrelevant and therefore not
+ // // computed. This field and `url` are mutually exclusive.
+ // .path = "foo",
+ //
+ // // When this is set to `true`, a package is declared to be lazily
+ // // fetched. This makes the dependency only get fetched if it is
+ // // actually used.
+ // .lazy = false,
+ //},
+ },
+
+ // Specifies the set of files and directories that are included in this package.
+ // Only files and directories listed here are included in the `hash` that
+ // is computed for this package. Only files listed here will remain on disk
+ // when using the zig package manager. As a rule of thumb, one should list
+ // files required for compilation plus any license(s).
+ // Paths are relative to the build root. Use the empty string (`""`) to refer to
+ // the build root itself.
+ // A directory listed here means that all files within, recursively, are included.
+ .paths = .{
+ "build.zig",
+ "build.zig.zon",
+ "src",
+ // For example...
+ //"LICENSE",
+ //"README.md",
+ },
+}
diff --git a/readme.txt b/readme.txt
new file mode 100644
index 0000000..a7066f3
--- /dev/null
+++ b/readme.txt
@@ -0,0 +1,10 @@
+sleep — tiny Zig sleep(1) clone using raw syscalls and a naked _start.
+
+build: ./zig-linux-x86_64-0.14.0/zig build
+run: ./zig-out/bin/sleep 2.5
+
+notes:
+- no libc, no stdlib entry, only write/nanosleep/exit syscalls.
+- parses integer or fractional seconds up to 9 decimal places.
+- retries on EINTR using remaining time from nanosleep.
+- _start sets up args manually; keep runtime safety off there.
diff --git a/sleep.zig b/sleep.zig
new file mode 100644
index 0000000..2cd043b
--- /dev/null
+++ b/sleep.zig
@@ -0,0 +1,181 @@
+// sleep.zig
+
+const syscall = struct {
+ pub const write = 1;
+ pub const nanosleep = 35;
+ pub const exit = 60;
+};
+
+const EINTR = 4;
+const MAX_SECONDS = 2147483647; // INT_MAX
+
+fn writeSyscall(fd: u32, buf: [*]const u8, count: usize) usize {
+ var result: usize = undefined;
+ asm volatile (
+ \\ mov %[syscall_num], %%rax
+ \\ mov %[fd], %%rdi
+ \\ mov %[buf], %%rsi
+ \\ mov %[count], %%rdx
+ \\ syscall
+ : [result] "={rax}" (result)
+ : [syscall_num] "r" (@as(usize, syscall.write)),
+ [fd] "r" (@as(usize, fd)),
+ [buf] "r" (@intFromPtr(buf)),
+ [count] "r" (count)
+ : "rax", "rdi", "rsi", "rdx", "rcx", "r11", "memory"
+ );
+ return result;
+}
+
+fn nanosleepSyscall(req: *const Timespec, rem: ?*Timespec) isize {
+ var result: isize = undefined;
+ asm volatile (
+ \\ mov %[syscall_num], %%rax
+ \\ mov %[req], %%rdi
+ \\ mov %[rem], %%rsi
+ \\ syscall
+ : [result] "={rax}" (result)
+ : [syscall_num] "r" (@as(usize, syscall.nanosleep)),
+ [req] "r" (@intFromPtr(req)),
+ [rem] "r" (if (rem) |r| @intFromPtr(r) else @as(usize, 0))
+ : "rax", "rdi", "rsi", "rcx", "r11", "memory"
+ );
+ return result;
+}
+
+fn exitSyscall(code: u8) noreturn {
+ asm volatile (
+ \\ mov %[syscall_num], %%rax
+ \\ mov %[code], %%rdi
+ \\ syscall
+ :
+ : [syscall_num] "r" (@as(usize, syscall.exit)),
+ [code] "r" (@as(usize, code))
+ : "rax", "rdi", "memory"
+ );
+ unreachable;
+}
+
+const Timespec = extern struct {
+ tv_sec: u64,
+ tv_nsec: u64,
+};
+
+const ParseResult = struct {
+ seconds: u64,
+ nanos: u64,
+};
+
+fn parseTime(str: [*:0]const u8) ?ParseResult {
+ var seconds: u64 = 0;
+ var nanos: u64 = 0;
+ var i: usize = 0;
+ var saw_dot = false;
+ var decimal_places: u32 = 0;
+
+ if (str[0] == 0) return null;
+
+ while (str[i] != 0) : (i += 1) {
+ const c = str[i];
+
+ if (c == '.') {
+ if (saw_dot) return null; // Multiple dots
+ saw_dot = true;
+ continue;
+ }
+
+ if (c < '0' or c > '9') return null;
+
+ const digit = c - '0';
+
+ if (!saw_dot) {
+ const new_seconds = seconds * 10 + digit;
+ if (new_seconds < seconds or new_seconds > MAX_SECONDS) return null;
+ seconds = new_seconds;
+ } else {
+ if (decimal_places >= 9) continue;
+ nanos = nanos * 10 + digit;
+ decimal_places += 1;
+ }
+ }
+
+ while (decimal_places < 9) : (decimal_places += 1) {
+ nanos *= 10;
+ }
+
+ return ParseResult{ .seconds = seconds, .nanos = nanos };
+}
+
+fn writeNumber(n: u64) void {
+ if (n == 0) {
+ _ = writeSyscall(1, "0", 1);
+ return;
+ }
+
+ var buf: [20]u8 = undefined; // u64 max is 20 digits
+ var i: usize = 0;
+ var num = n;
+
+ while (num > 0) : (i += 1) {
+ buf[i] = @as(u8, @intCast(num % 10)) + '0';
+ num /= 10;
+ }
+
+ var j: usize = 0;
+ while (j < i) : (j += 1) {
+ const c = buf[i - 1 - j];
+ _ = writeSyscall(1, &c, 1);
+ }
+}
+
+fn start(stack_ptr: [*]usize) noreturn {
+ const argc = stack_ptr[0];
+ const argv: [*][*:0]u8 = @ptrCast(stack_ptr + 1);
+
+ if (argc != 2) {
+ const usage_msg = "Usage: sleep NUMBER[.FRACTION]\n";
+ _ = writeSyscall(2, usage_msg, usage_msg.len);
+ exitSyscall(1);
+ }
+
+ const parsed = parseTime(argv[1]) orelse {
+ const error_msg = "sleep: invalid time interval\n";
+ _ = writeSyscall(2, error_msg, error_msg.len);
+ exitSyscall(1);
+ };
+
+ var req = Timespec{
+ .tv_sec = parsed.seconds,
+ .tv_nsec = parsed.nanos,
+ };
+ var rem = Timespec{
+ .tv_sec = 0,
+ .tv_nsec = 0,
+ };
+
+ while (true) {
+ const result = nanosleepSyscall(&req, &rem);
+
+ if (result == 0) break;
+
+ const err = @as(usize, @bitCast(-result));
+ if (err != EINTR) break;
+
+ req = rem;
+ }
+
+ exitSyscall(0);
+}
+
+pub export fn _start() callconv(.Naked) noreturn {
+ @setRuntimeSafety(false);
+ asm volatile (
+ \\ xor %edi, %edi
+ \\ mov %rsp, %rsi
+ \\ jmp *%[start_fn]
+ :
+ : [start_fn] "r" (&start)
+ : "rdi", "rsi", "memory"
+ );
+ unreachable;
+}