Cleaner freeing of input line, proper SIGINT handling

src/main.zig

@@ -11,7 +11,7 @@ pub fn main() anyerror!void {
     while (true) {
         
         var input = prompt.readline("topiku> ") orelse break;
-        defer std.c.free(&input);
+        defer prompt.free(input);
         
         try stdout.print(">>> {s}\n", .{input});
     }

src/prompt.zig

@@ -5,8 +5,11 @@ const ceditline = @cImport({
 const std = @import("std");
 const io = std.io;
 
-pub fn readline(prompt: [*c]const u8) ?[]u8 {
-    var line = ceditline.readline(@as([*c]const u8, prompt));
+const __sighandler = ?fn (c_int) callconv(.C) void;
+extern fn signal(sig: c_int, handler: __sighandler) __sighandler;
+
+pub fn readline(prompt: []const u8) ?[]u8 {
+    var line = ceditline.readline(@as([*c]const u8, prompt.ptr));
     if (line == 0) {
         std.c.free(line);
         return null;
@@ -14,8 +17,18 @@ pub fn readline(prompt: [*c]const u8) ?[]u8 {
     return std.mem.sliceTo(line, 0);
 }
 
+pub fn free(slice: []u8) void {
+    std.c.free(slice.ptr);
+}
+
 pub fn init() void {
     ceditline.rl_initialize();
+    _ = signal(std.os.SIG.INT, exit);
+}
+
+fn exit(_ : c_int) callconv(.C) void {
+    deinit();
+    std.os.exit(0);
 }
 
 pub fn deinit() void {