Merge pull request #8 from kubkon/handle-args

Implement different zld drivers via symlinks and refactor usage/options per driver

Author: kubkon

README.md

@@ -12,7 +12,8 @@ You will need latest Zig in your path. You can get nightly binaries from [here](
 $ zig build
 ```
 
-This will create the `zld` binary in `zig-out/bin/zld`. You can then use it like you'd use a standard linker.
+This will create the `ld.zld` (Elf), `ld64.zld` (MachO) and `link-zld` (Coff) binaries in `zig-out/bin/`.
+You can then use it like you'd use a standard linker.
 
 ```
 $ cat <<EOF > hello.c
@@ -30,8 +31,11 @@ $ clang -c hello.c
 # Or, create .o using zig cc
 $ zig cc -c hello.c
 
-# Link away!
-$ ./zig-out/bin/zld hello.o -o hello
+# On macOS
+$ ./zig-out/bin/ld64.zld hello.o -o hello
+
+# On Linux
+$ ./zig-out/bin/ld.zld hello.o -o hello
 
 # Run!
 $ ./hello

build.zig

@@ -1,14 +1,16 @@
-const Builder = @import("std").build.Builder;
+const std = @import("std");
+const fs = std.fs;
+const log = std.log;
+
+const Allocator = std.mem.Allocator;
+const Builder = std.build.Builder;
+const FileSource = std.build.FileSource;
+const LibExeObjStep = std.build.LibExeObjStep;
+const InstallDir = std.build.InstallDir;
+const Step = std.build.Step;
 
 pub fn build(b: *Builder) 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 release options allow the person running `zig build` to select
-    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall.
     const mode = b.standardReleaseOptions();
 
     const enable_logging = b.option(bool, "log", "Whether to enable logging") orelse false;
@@ -27,17 +29,13 @@ pub fn build(b: *Builder) void {
     const exe_opts = b.addOptions();
     exe.addOptions("build_options", exe_opts);
     exe_opts.addOption(bool, "enable_logging", enable_logging);
-
     exe.install();
 
-    const run_cmd = exe.run();
-    run_cmd.step.dependOn(b.getInstallStep());
-    if (b.args) |args| {
-        run_cmd.addArgs(args);
-    }
+    const elf_symlink = symlink(exe, "ld.zld");
+    elf_symlink.step.dependOn(&exe.step);
 
-    const run_step = b.step("run", "Run the app");
-    run_step.dependOn(&run_cmd.step);
+    const macho_symlink = symlink(exe, "ld64.zld");
+    macho_symlink.step.dependOn(&exe.step);
 
     const tests = b.addTest("src/test.zig");
     tests.setBuildMode(mode);
@@ -47,8 +45,52 @@ pub fn build(b: *Builder) void {
     const test_opts = b.addOptions();
     tests.addOptions("build_options", test_opts);
     test_opts.addOption(bool, "enable_qemu", is_qemu_enabled);
+    test_opts.addOption(bool, "enable_logging", enable_logging);
 
     const test_step = b.step("test", "Run library and end-to-end tests");
-    test_step.dependOn(&exe.step);
     test_step.dependOn(&tests.step);
 }
+
+fn symlink(exe: *LibExeObjStep, name: []const u8) *CreateSymlinkStep {
+    const step = CreateSymlinkStep.create(exe.builder, exe.getOutputSource(), name);
+    exe.builder.getInstallStep().dependOn(&step.step);
+    return step;
+}
+
+const CreateSymlinkStep = struct {
+    pub const base_id = .custom;
+
+    step: Step,
+    builder: *Builder,
+    source: FileSource,
+    target: []const u8,
+
+    pub fn create(
+        builder: *Builder,
+        source: FileSource,
+        target: []const u8,
+    ) *CreateSymlinkStep {
+        const self = builder.allocator.create(CreateSymlinkStep) catch unreachable;
+        self.* = CreateSymlinkStep{
+            .builder = builder,
+            .step = Step.init(.log, builder.fmt("symlink {s} -> {s}", .{
+                source.getDisplayName(),
+                target,
+            }), builder.allocator, make),
+            .source = source,
+            .target = builder.dupe(target),
+        };
+        return self;
+    }
+
+    fn make(step: *Step) anyerror!void {
+        const self = @fieldParentPtr(CreateSymlinkStep, "step", step);
+        const rel_source = fs.path.basename(self.source.getPath(self.builder));
+        const source_path = self.builder.getInstallPath(.bin, rel_source);
+        const target_path = self.builder.getInstallPath(.bin, self.target);
+        fs.atomicSymLink(self.builder.allocator, source_path, target_path) catch |err| {
+            log.err("Unable to symlink {s} -> {s}", .{ source_path, target_path });
+            return err;
+        };
+    }
+};

src/Coff.zig

@@ -10,15 +10,17 @@ const mem = std.mem;
 
 const Allocator = mem.Allocator;
 const Object = @import("Coff/Object.zig");
+pub const Options = @import("Coff/Options.zig");
 const Zld = @import("Zld.zig");
 
 pub const base_tag = Zld.Tag.coff;
 
 base: Zld,
+options: Options,
 
 objects: std.ArrayListUnmanaged(Object) = .{},
 
-pub fn openPath(allocator: Allocator, options: Zld.Options) !*Coff {
+pub fn openPath(allocator: Allocator, options: Options) !*Coff {
     const file = try options.emit.directory.createFile(options.emit.sub_path, .{
         .truncate = true,
         .read = true,
@@ -34,32 +36,30 @@ pub fn openPath(allocator: Allocator, options: Zld.Options) !*Coff {
     return self;
 }
 
-fn createEmpty(gpa: Allocator, options: Zld.Options) !*Coff {
+fn createEmpty(gpa: Allocator, options: Options) !*Coff {
     const self = try gpa.create(Coff);
 
     self.* = .{
         .base = .{
             .tag = .coff,
-            .options = options,
             .allocator = gpa,
             .file = undefined,
         },
+        .options = options,
     };
 
     return self;
 }
 
 pub fn deinit(self: *Coff) void {
-    self.closeFiles();
-
     for (self.objects.items) |*object| {
         object.deinit(self.base.allocator);
     }
 
     self.objects.deinit(self.base.allocator);
 }
 
-pub fn closeFiles(self: Coff) void {
+pub fn closeFiles(self: *const Coff) void {
     for (self.objects.items) |object| {
         object.file.close();
     }
@@ -70,9 +70,9 @@ pub fn flush(self: *Coff) !void {
 
     var positionals = std.ArrayList([]const u8).init(gpa);
     defer positionals.deinit();
-    try positionals.ensureTotalCapacity(self.base.options.positionals.len);
+    try positionals.ensureTotalCapacity(self.options.positionals.len);
 
-    for (self.base.options.positionals) |obj| {
+    for (self.options.positionals) |obj| {
         positionals.appendAssumeCapacity(obj.path);
     }
 
@@ -110,7 +110,7 @@ fn parseObject(self: *Coff, path: []const u8) !bool {
         .file = file,
     };
 
-    object.parse(self.base.allocator, self.base.options.target) catch |err| switch (err) {
+    object.parse(self.base.allocator, self.options.target.cpu_arch.?) catch |err| switch (err) {
         error.EndOfStream => {
             object.deinit(self.base.allocator);
             return false;

src/Coff/Object.zig

@@ -96,10 +96,10 @@ pub const IMAGE_SYM_CLASS_SECTION = 104;
 pub const IMAGE_SYM_CLASS_WEAK_EXTERNAL = 105;
 pub const IMAGE_SYM_CLASS_CLR_TOKEN = 107;
 
-// comptime {
-//     assert(@sizeOf(Symbol) == 18);
-//     assert(@sizeOf(CoffHeader) == 20);
-// }
+comptime {
+    assert(@sizeOf(Symbol) == 18);
+    assert(@sizeOf(CoffHeader) == 20);
+}
 
 pub fn deinit(self: *Object, allocator: Allocator) void {
     self.symtab.deinit(allocator);
@@ -108,7 +108,7 @@ pub fn deinit(self: *Object, allocator: Allocator) void {
     allocator.free(self.name);
 }
 
-pub fn parse(self: *Object, allocator: Allocator, target: std.Target) !void {
+pub fn parse(self: *Object, allocator: Allocator, cpu_arch: std.Target.Cpu.Arch) !void {
     const reader = self.file.reader();
     const header = try reader.readStruct(CoffHeader);
 
@@ -117,10 +117,10 @@ pub fn parse(self: *Object, allocator: Allocator, target: std.Target) !void {
         return error.NotObject;
     }
 
-    if (header.machine != @enumToInt(target.cpu.arch.toCoffMachine())) {
+    if (header.machine != @enumToInt(cpu_arch.toCoffMachine())) {
         log.debug("Invalid architecture {any}, expected {any}", .{
             header.machine,
-            target.cpu.arch.toCoffMachine(),
+            cpu_arch.toCoffMachine(),
         });
         return error.InvalidCpuArch;
     }

src/Coff/Options.zig

@@ -0,0 +1,91 @@
+const Options = @This();
+
+const std = @import("std");
+const builtin = @import("builtin");
+const io = std.io;
+const mem = std.mem;
+const process = std.process;
+
+const Allocator = mem.Allocator;
+const CrossTarget = std.zig.CrossTarget;
+const Coff = @import("../Coff.zig");
+const Zld = @import("../Zld.zig");
+
+const usage =
+    \\Usage: link-zld [files...]
+    \\
+    \\General Options:
+    \\-l[name]                      Specify library to link against
+    \\-L[path]                      Specify library search dir
+    \\-o [path]                     Specify output path for the final artifact
+    \\-h, --help                    Print this help and exit
+    \\--debug-log [scope]           Turn on debugging logs for [scope] (requires zld compiled with -Dlog)
+;
+
+emit: Zld.Emit,
+output_mode: Zld.OutputMode,
+target: CrossTarget,
+positionals: []const Zld.LinkObject,
+libs: std.StringArrayHashMap(Zld.SystemLib),
+lib_dirs: []const []const u8,
+
+pub fn parseArgs(arena: Allocator, ctx: Zld.MainCtx) !Options {
+    if (ctx.args.len == 0) {
+        ctx.printSuccess("{s}", .{usage});
+    }
+
+    var positionals = std.ArrayList(Zld.LinkObject).init(arena);
+    var libs = std.StringArrayHashMap(Zld.SystemLib).init(arena);
+    var lib_dirs = std.ArrayList([]const u8).init(arena);
+    var out_path: ?[]const u8 = null;
+
+    const Iterator = struct {
+        args: []const []const u8,
+        i: usize = 0,
+        fn next(it: *@This()) ?[]const u8 {
+            if (it.i >= it.args.len) {
+                return null;
+            }
+            defer it.i += 1;
+            return it.args[it.i];
+        }
+    };
+    var args_iter = Iterator{ .args = ctx.args };
+
+    while (args_iter.next()) |arg| {
+        if (mem.eql(u8, arg, "--help") or mem.eql(u8, arg, "-h")) {
+            ctx.printSuccess("{s}", .{usage});
+        } else if (mem.eql(u8, arg, "--debug-log")) {
+            const scope = args_iter.next() orelse ctx.printFailure("Expected log scope after {s}", .{arg});
+            try ctx.log_scopes.append(scope);
+        } else if (mem.startsWith(u8, arg, "-l")) {
+            try libs.put(arg[2..], .{});
+        } else if (mem.startsWith(u8, arg, "-L")) {
+            try lib_dirs.append(arg[2..]);
+        } else if (mem.eql(u8, arg, "-o")) {
+            out_path = args_iter.next() orelse
+                ctx.printFailure("Expected output path after {s}", .{arg});
+        } else {
+            try positionals.append(.{
+                .path = arg,
+                .must_link = true,
+            });
+        }
+    }
+
+    if (positionals.items.len == 0) {
+        ctx.printFailure("Expected at least one input .o file", .{});
+    }
+
+    return Options{
+        .emit = .{
+            .directory = std.fs.cwd(),
+            .sub_path = out_path orelse "a.out",
+        },
+        .target = CrossTarget.fromTarget(builtin.target),
+        .output_mode = .exe,
+        .positionals = positionals.items,
+        .libs = libs,
+        .lib_dirs = lib_dirs.items,
+    };
+}