coff: Add initial Coff support

src/Coff.zig

@@ -0,0 +1,59 @@
+const Coff = @This();
+
+const std = @import("std");
+const assert = std.debug.assert;
+const coff = std.coff;
+const fs = std.fs;
+const log = std.log.scoped(.coff);
+const mem = std.mem;
+
+const Allocator = mem.Allocator;
+const Zld = @import("Zld.zig");
+
+pub const base_tag = Zld.Tag.coff;
+
+base: Zld,
+
+pub fn openPath(allocator: *Allocator, options: Zld.Options) !*Coff {
+    const file = try options.emit.directory.createFile(options.emit.sub_path, .{
+        .truncate = true,
+        .read = true,
+        .mode = if (std.Target.current.os.tag == .windows) 0 else 0o777,
+    });
+    errdefer file.close();
+
+    const self = try createEmpty(allocator, options);
+    errdefer allocator.destroy(self);
+
+    self.base.file = file;
+
+    return self;
+}
+
+fn createEmpty(gpa: *Allocator, options: Zld.Options) !*Coff {
+    const self = try gpa.create(Coff);
+
+    self.* = .{
+        .base = .{
+            .tag = .coff,
+            .options = options,
+            .allocator = gpa,
+            .file = undefined,
+        },
+    };
+
+    return self;
+}
+
+pub fn deinit(self: *Coff) void {
+    _ = self;
+}
+
+pub fn closeFiles(self: Coff) void {
+    _ = self;
+}
+
+pub fn flush(self: *Coff) !void {
+    _ = self;
+    return error.TODOFlushInCoffLinker;
+}

src/Zld.zig

@@ -9,6 +9,7 @@ const process = std.process;
 const Allocator = mem.Allocator;
 const Elf = @import("Elf.zig");
 const MachO = @import("MachO.zig");
+const Coff = @import("Coff.zig");
 
 tag: Tag,
 allocator: *Allocator,
@@ -50,7 +51,7 @@ pub fn openPath(allocator: *Allocator, options: Options) !*Zld {
     return switch (options.target.os.tag) {
         .linux => &(try Elf.openPath(allocator, options)).base,
         .macos => &(try MachO.openPath(allocator, options)).base,
-        .windows => error.TODOCoffLinker,
+        .windows => &(try Coff.openPath(allocator, options)).base,
         else => error.Unimplemented,
     };
 }
@@ -59,15 +60,15 @@ pub fn deinit(base: *Zld) void {
     switch (base.tag) {
         .elf => @fieldParentPtr(Elf, "base", base).deinit(),
         .macho => @fieldParentPtr(MachO, "base", base).deinit(),
-        else => {},
+        .coff => @fieldParentPtr(Coff, "base", base).deinit(),
     }
 }
 
 pub fn closeFiles(base: Zld) void {
     switch (base.tag) {
         .elf => @fieldParentPtr(Elf, "base", &base).closeFiles(),
         .macho => @fieldParentPtr(MachO, "base", &base).closeFiles(),
-        else => {},
+        .coff => @fieldParentPtr(Coff, "base", &base).closeFiles(),
     }
     base.file.close();
 }
@@ -76,6 +77,6 @@ pub fn flush(base: *Zld) !void {
     switch (base.tag) {
         .elf => try @fieldParentPtr(Elf, "base", base).flush(),
         .macho => try @fieldParentPtr(MachO, "base", base).flush(),
-        .coff => return error.TODOCoffLinker,
+        .coff => try @fieldParentPtr(Coff, "base", base).flush(),
     }
 }