move os differences to build.zig

Since windows is more of a framework model than a library model,
it is simpler to just start with a different entry point

build.zig

@@ -11,9 +11,15 @@ pub fn build(b: *std.build.Builder) void {
     // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall.
     const mode = b.standardReleaseOptions();
 
-    const exe = b.addExecutable("clipboard", "src/main.zig");
+    const exe = switch (target.getOs().tag) {
+        .linux => b.addExecutable("clipboard", "src/main-linux.zig"),
+        .windows => b.addExecutable("clipboard", "src/main-windows.zig"),
+        else => std.os.exit(1),
+    };
+
     exe.setTarget(target);
     exe.setBuildMode(mode);
+    exe.linkLibC();
     if (target.getOs().tag == .linux) {
         // LibX11 1.7.2: https://gitlab.freedesktop.org/xorg/lib/libx11/-/archive/libX11-1.7.2/libx11-libX11-1.7.2.tar.gz
         // LibXfixes 5.0.3: https://gitlab.freedesktop.org/xorg/lib/libxfixes/-/archive/libXfixes-5.0.3/libxfixes-libXfixes-5.0.3.tar.gz
@@ -21,7 +27,6 @@ pub fn build(b: *std.build.Builder) void {
         // We can download the above by taking each url and processing in a
         // command e.g.:
         // curl <url> | tar xz --wildcards '*.h'
-        exe.linkLibC();
         exe.addIncludeDir("libx11-libX11-1.7.2/include");
         exe.addIncludeDir("libxfixes-libXfixes-5.0.3/include");
         exe.addIncludeDir("xorgproto-xorgproto-2021.5/include");

src/main-linux.zig

@@ -5,6 +5,62 @@ const c = @cImport({
     @cInclude("X11/extensions/Xfixes.h");
 });
 
+pub fn main() !u8 {
+    var watch = false;
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer _ = gpa.deinit();
+    const allocator = &gpa.allocator;
+    var args = std.process.args();
+    defer args.deinit();
+    while (args.next(allocator)) |arg_or_err| {
+        const arg = try arg_or_err;
+        defer allocator.free(arg);
+        if (std.mem.eql(u8, arg, "-w")) {
+            watch = true;
+            break;
+        }
+    }
+    clipboardAction(watch) catch return 1;
+    return 0;
+}
+
+pub fn clipboardAction(watch: bool) !void {
+    const stdout = std.io.getStdOut().writer();
+    var display: *c.Display = c.XOpenDisplay(null).?;
+    defer _ = c.XCloseDisplay(display);
+    const default_screen = c.XDefaultScreen(display);
+    var color = c.XBlackPixel(display, default_screen);
+    var window = c.XCreateSimpleWindow(display, c.XDefaultRootWindow(display), 0, 0, 1, 1, 0, color, color);
+    defer _ = c.XDestroyWindow(display, window);
+    // Watch will not return
+    if (watch) try watchClip(display, window, "CLIPBOARD", stdout);
+    var result = (try printSelection(display, window, "CLIPBOARD", "UTF8_STRING", stdout)) or
+        (try printSelection(display, window, "CLIPBOARD", "STRING", stdout));
+    if (!result) return error.ClipboardActionFailed;
+}
+
+fn watchClip(display: *c.Display, window: c.Window, bufname: [*c]const u8, writer: anytype) !void {
+    var event_base: c_int = undefined;
+    var error_base: c_int = undefined;
+    var event: c.XEvent = undefined;
+    var bufid = c.XInternAtom(display, bufname, c.False);
+
+    _ = c.XFixesQueryExtension(display, &event_base, &error_base);
+    _ = c.XFixesSelectSelectionInput(display, c.XDefaultRootWindow(display), bufid, c.XFixesSetSelectionOwnerNotifyMask);
+
+    while (true) {
+        _ = c.XNextEvent(display, &event);
+
+        if (event.type == event_base + c.XFixesSelectionNotify and
+            event.xselection.property == bufid)
+        {
+            _ = try writer.print("y", .{});
+            if (!try printSelection(display, window, bufname, "UTF8_STRING", writer))
+                _ = try printSelection(display, window, bufname, "STRING", writer);
+        }
+    }
+}
+
 fn printSelection(display: *c.Display, window: c.Window, bufname: [*c]const u8, fmtname: [*c]const u8, writer: anytype) !bool {
     var ressize: c_ulong = undefined;
     var restail: c_ulong = undefined;
@@ -30,6 +86,13 @@ fn printSelection(display: *c.Display, window: c.Window, bufname: [*c]const u8,
 
         if (fmtid == incrid) {
             ressize = 1;
+            var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+            defer _ = gpa.deinit();
+            var arena_allocator = std.heap.ArenaAllocator.init(&gpa.allocator);
+            defer arena_allocator.deinit();
+            var buffer = std.ArrayList(u8).init(&arena_allocator.allocator);
+            defer buffer.deinit();
+            // try writer.print("BIG:", .{});
             while (ressize > 0) {
                 _ = c.XNextEvent(display, &event);
                 while (event.type != c.PropertyNotify or event.xproperty.atom != propid or event.xproperty.state != c.PropertyNewValue) {
@@ -37,61 +100,12 @@ fn printSelection(display: *c.Display, window: c.Window, bufname: [*c]const u8,
                 }
 
                 _ = c.XGetWindowProperty(display, window, propid, 0, c.LONG_MAX / 4, c.True, c.AnyPropertyType, &fmtid, &resbits, &ressize, &restail, &result);
-                defer _ = c.XFree(result);
+                //defer _ = c.XFree(result); // Creates double free error, but not sure why
-                try writer.print("{s}", .{result});
+                try buffer.appendSlice(try std.fmt.allocPrint(&arena_allocator.allocator, "{s}", .{result}));
             }
+            try writer.print("{s}", .{buffer.items});
         }
         return true;
     } else // request failed, e.g. owner can't convert to the target format
     return false;
 }
-
-fn watch(display: *c.Display, window: c.Window, bufname: [*c]const u8, writer: anytype) !void {
-    var event_base: c_int = undefined;
-    var error_base: c_int = undefined;
-    var event: c.XEvent = undefined;
-    var bufid = c.XInternAtom(display, bufname, c.False);
-
-    _ = c.XFixesQueryExtension(display, &event_base, &error_base);
-    _ = c.XFixesSelectSelectionInput(display, c.XDefaultRootWindow(display), bufid, c.XFixesSetSelectionOwnerNotifyMask);
-
-    while (true) {
-        _ = c.XNextEvent(display, &event);
-
-        // _ = try writer.print("{d} == {d} + {d}. {d} == {d}", .{ event.type, event_base, c.XFixesSelectionNotify, event.xselection.selection, bufid });
-        // _ = std.debug.print("{}", .{event.xselection});
-
-        if (event.type == event_base + c.XFixesSelectionNotify and
-            event.xselection.property == bufid)
-        {
-            _ = try writer.print("y", .{});
-            if (!try printSelection(display, window, bufname, "UTF8_STRING", writer))
-                _ = try printSelection(display, window, bufname, "STRING", writer);
-        }
-    }
-}
-
-pub fn clipboardAction() !void {
-    const stdout = std.io.getStdOut().writer();
-    var display: *c.Display = c.XOpenDisplay(null).?;
-    defer _ = c.XCloseDisplay(display);
-    const default_screen = c.XDefaultScreen(display);
-    var color = c.XBlackPixel(display, default_screen);
-    var window = c.XCreateSimpleWindow(display, c.XDefaultRootWindow(display), 0, 0, 1, 1, 0, color, color);
-    defer _ = c.XDestroyWindow(display, window);
-    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
-    defer _ = gpa.deinit();
-    const allocator = &gpa.allocator;
-    var args = std.process.args();
-    defer args.deinit();
-    while (args.next(allocator)) |arg_or_err| {
-        const arg = try arg_or_err;
-        defer allocator.free(arg);
-        if (std.mem.eql(u8, arg, "-w")) {
-            try watch(display, window, "CLIPBOARD", stdout);
-        }
-    }
-    var result = (try printSelection(display, window, "CLIPBOARD", "UTF8_STRING", stdout)) or
-        (try printSelection(display, window, "CLIPBOARD", "STRING", stdout));
-    if (!result) return error.ClipboardActionFailed;
-}

src/main-windows.zig

@@ -0,0 +1,10 @@
+const std = @import("std");
+const win = @cImport({
+    @cInclude("windows.h");
+});
+pub fn clipboardAction(watch: bool) !void {
+    _ = watch;
+    const stdout = std.io.getStdOut().writer();
+    try stdout.print("All your codebase are belong to us", .{});
+    try stdout.print("{d}", .{win.HINSTANCE});
+}

src/main.zig

@@ -1,11 +0,0 @@
-const std = @import("std");
-
-pub fn main() !u8 {
-    if (std.builtin.os.tag == .linux) {
-        @import("linux.zig").clipboardAction() catch return 1;
-    }
-    if (std.builtin.os.tag == .windows) {
-        @import("windows.zig").clipboardAction() catch return 1;
-    }
-    return 0;
-}

src/windows.zig

@@ -1,6 +0,0 @@
-const std = @import("std");
-
-pub fn clipboardAction() !void {
-    const stdout = std.io.getStdOut().writer();
-    try stdout.print("All your codebase are belong to us", .{});
-}