Commit 9fb4d1fd6c

Andrew Kelley <superjoe30@gmail.com>
2017-09-08 05:10:23
std: os.ChildProcess knows when its child died
using signal handlers
1 parent 9dfaf31
src/ir.cpp
@@ -11513,6 +11513,28 @@ static TypeTableEntry *ir_analyze_instruction_field_ptr(IrAnalyze *ira, IrInstru
                         buf_ptr(&child_type->name), buf_ptr(field_name)));
                 return ira->codegen->builtin_types.entry_invalid;
             }
+        } else if (child_type->id == TypeTableEntryIdArray) {
+            if (buf_eql_str(field_name, "child")) {
+                bool ptr_is_const = true;
+                bool ptr_is_volatile = false;
+                return ir_analyze_const_ptr(ira, &field_ptr_instruction->base,
+                    create_const_type(ira->codegen, child_type->data.array.child_type),
+                    ira->codegen->builtin_types.entry_type,
+                    ConstPtrMutComptimeConst, ptr_is_const, ptr_is_volatile);
+            } else if (buf_eql_str(field_name, "len")) {
+                bool ptr_is_const = true;
+                bool ptr_is_volatile = false;
+                return ir_analyze_const_ptr(ira, &field_ptr_instruction->base,
+                    create_const_unsigned_negative(ira->codegen->builtin_types.entry_num_lit_int,
+                        child_type->data.array.len, false),
+                    ira->codegen->builtin_types.entry_num_lit_int,
+                    ConstPtrMutComptimeConst, ptr_is_const, ptr_is_volatile);
+            } else {
+                ir_add_error(ira, &field_ptr_instruction->base,
+                    buf_sprintf("type '%s' has no member called '%s'",
+                        buf_ptr(&child_type->name), buf_ptr(field_name)));
+                return ira->codegen->builtin_types.entry_invalid;
+            }
         } else {
             ir_add_error(ira, &field_ptr_instruction->base,
                 buf_sprintf("type '%s' does not support field access", buf_ptr(&child_type->name)));
std/os/child_process.zig
@@ -8,20 +8,31 @@ const assert = debug.assert;
 const BufMap = @import("../buf_map.zig").BufMap;
 const builtin = @import("builtin");
 const Os = builtin.Os;
+const LinkedList = @import("../linked_list.zig").LinkedList;
 
 error PermissionDenied;
 error ProcessNotFound;
 
+var children_nodes = LinkedList(&ChildProcess).init();
+
 pub const ChildProcess = struct {
     pid: i32,
+
     err_pipe: [2]i32,
+    llnode: LinkedList(&ChildProcess).Node,
+    allocator: &mem.Allocator,
+
+    stdin: ?&io.OutStream,
+    stdout: ?&io.InStream,
+    stderr: ?&io.InStream,
 
-    stdin: ?io.OutStream,
-    stdout: ?io.InStream,
-    stderr: ?io.InStream,
+    term: ?%Term,
+
+    /// Possibly called from a signal handler.
+    onTerm: ?fn(&ChildProcess),
 
     pub const Term = enum {
-        Clean: i32,
+        Exited: i32,
         Signal: i32,
         Stopped: i32,
         Unknown: i32,
@@ -34,13 +45,15 @@ pub const ChildProcess = struct {
         Close,
     };
 
+    /// onTerm can be called before `spawn` returns.
     pub fn spawn(exe_path: []const u8, args: []const []const u8,
         cwd: ?[]const u8, env_map: &const BufMap,
-        stdin: StdIo, stdout: StdIo, stderr: StdIo, allocator: &Allocator) -> %ChildProcess
+        stdin: StdIo, stdout: StdIo, stderr: StdIo,
+        onTerm: ?fn(&ChildProcess), allocator: &Allocator) -> %&ChildProcess
     {
         switch (builtin.os) {
             Os.linux, Os.macosx, Os.ios, Os.darwin => {
-                return spawnPosix(exe_path, args, cwd, env_map, stdin, stdout, stderr, allocator);
+                return spawnPosix(exe_path, args, cwd, env_map, stdin, stdout, stderr, onTerm, allocator);
             },
             else => @compileError("Unsupported OS"),
         }
@@ -48,6 +61,12 @@ pub const ChildProcess = struct {
 
     /// Forcibly terminates child process and then cleans up all resources.
     pub fn kill(self: &ChildProcess) -> %Term {
+        block_SIGCHLD();
+        defer restore_SIGCHLD();
+
+        if (self.term) |term| {
+            return term;
+        }
         const ret = posix.kill(self.pid, posix.SIGTERM);
         const err = posix.getErrno(ret);
         if (err > 0) {
@@ -58,37 +77,60 @@ pub const ChildProcess = struct {
                 else => error.Unexpected,
             };
         }
-        return self.wait();
+        self.waitUnwrapped();
+        return ??self.term;
     }
 
     /// Blocks until child process terminates and then cleans up all resources.
     pub fn wait(self: &ChildProcess) -> %Term {
-        defer {
-            os.posixClose(self.err_pipe[0]);
-            os.posixClose(self.err_pipe[1]);
-        };
+        block_SIGCHLD();
+        defer restore_SIGCHLD();
 
+        if (self.term) |term| {
+            return term;
+        }
+
+        self.waitUnwrapped();
+        return ??self.term;
+    }
+
+    fn waitUnwrapped(self: &ChildProcess) {
         var status: i32 = undefined;
         while (true) {
             const err = posix.getErrno(posix.waitpid(self.pid, &status, 0));
             if (err > 0) {
                 switch (err) {
-                    posix.EINVAL, posix.ECHILD => unreachable,
                     posix.EINTR => continue,
-                    else => {
-                        if (self.stdin) |*stdin| { stdin.close(); }
-                        if (self.stdout) |*stdout| { stdout.close(); }
-                        if (self.stderr) |*stderr| { stderr.close(); }
-                        return error.Unexpected;
-                    },
+                    else => unreachable,
                 }
             }
-            break;
+            self.cleanupStreams();
+            self.handleWaitResult(status);
+            return;
         }
+    }
+
+    fn handleWaitResult(self: &ChildProcess, status: i32) {
+        self.term = self.cleanupAfterWait(status);
+
+        if (self.onTerm) |onTerm| {
+            onTerm(self);
+        }
+    }
 
-        if (self.stdin) |*stdin| { stdin.close(); }
-        if (self.stdout) |*stdout| { stdout.close(); }
-        if (self.stderr) |*stderr| { stderr.close(); }
+    fn cleanupStreams(self: &ChildProcess) {
+        if (self.stdin) |stdin| { stdin.close(); self.allocator.free(stdin); }
+        if (self.stdout) |stdout| { stdout.close(); self.allocator.free(stdout); }
+        if (self.stderr) |stderr| { stderr.close(); self.allocator.free(stderr); }
+    }
+
+    fn cleanupAfterWait(self: &ChildProcess, status: i32) -> %Term {
+        children_nodes.remove(&self.llnode);
+
+        defer {
+            os.posixClose(self.err_pipe[0]);
+            os.posixClose(self.err_pipe[1]);
+        };
 
         // Write @maxValue(ErrInt) to the write end of the err_pipe. This is after
         // waitpid, so this write is guaranteed to be after the child
@@ -108,7 +150,7 @@ pub const ChildProcess = struct {
 
     fn statusToTerm(status: i32) -> Term {
         return if (posix.WIFEXITED(status)) {
-            Term.Clean { posix.WEXITSTATUS(status) }
+            Term.Exited { posix.WEXITSTATUS(status) }
         } else if (posix.WIFSIGNALED(status)) {
             Term.Signal { posix.WTERMSIG(status) }
         } else if (posix.WIFSTOPPED(status)) {
@@ -120,8 +162,12 @@ pub const ChildProcess = struct {
 
     fn spawnPosix(exe_path: []const u8, args: []const []const u8,
         maybe_cwd: ?[]const u8, env_map: &const BufMap,
-        stdin: StdIo, stdout: StdIo, stderr: StdIo, allocator: &Allocator) -> %ChildProcess
+        stdin: StdIo, stdout: StdIo, stderr: StdIo,
+        onTerm: ?fn(&ChildProcess), allocator: &Allocator) -> %&ChildProcess
     {
+        // TODO atomically set a flag saying that we already did this
+        install_SIGCHLD_handler();
+
         const stdin_pipe = if (stdin == StdIo.Pipe) %return makePipe() else undefined;
         %defer if (stdin == StdIo.Pipe) { destroyPipe(stdin_pipe); };
 
@@ -143,16 +189,39 @@ pub const ChildProcess = struct {
         const err_pipe = %return makePipe();
         %defer destroyPipe(err_pipe);
 
-        const pid = posix.fork();
-        const pid_err = posix.getErrno(pid);
+        const child = %return allocator.create(ChildProcess);
+        %defer allocator.destroy(child);
+
+        const stdin_ptr = if (stdin == StdIo.Pipe) {
+            %return allocator.create(io.OutStream)
+        } else {
+            null
+        };
+        const stdout_ptr = if (stdout == StdIo.Pipe) {
+            %return allocator.create(io.InStream)
+        } else {
+            null
+        };
+        const stderr_ptr = if (stderr == StdIo.Pipe) {
+            %return allocator.create(io.InStream)
+        } else {
+            null
+        };
+
+        block_SIGCHLD();
+        const pid_result = posix.fork();
+        const pid_err = posix.getErrno(pid_result);
         if (pid_err > 0) {
+            restore_SIGCHLD();
             return switch (pid_err) {
                 posix.EAGAIN, posix.ENOMEM, posix.ENOSYS => error.SystemResources,
                 else => error.Unexpected,
             };
         }
-        if (pid == 0) {
+        if (pid_result == 0) {
             // we are the child
+            restore_SIGCHLD();
+
             setUpChildIo(stdin, stdin_pipe[0], posix.STDIN_FILENO, dev_null_fd) %%
                 |err| forkChildErrReport(err_pipe[1], err);
             setUpChildIo(stdout, stdout_pipe[1], posix.STDOUT_FILENO, dev_null_fd) %%
@@ -170,45 +239,53 @@ pub const ChildProcess = struct {
         }
 
         // we are the parent
+        const pid = i32(pid_result);
+        if (stdin_ptr) |outstream| {
+            *outstream = io.OutStream {
+                .fd = stdin_pipe[1],
+                .handle = {},
+                .handle_id = {},
+                .buffer = undefined,
+                .index = 0,
+            };
+        }
+        if (stdout_ptr) |instream| {
+            *instream = io.InStream {
+                .fd = stdout_pipe[0],
+                .handle = {},
+                .handle_id = {},
+            };
+        }
+        if (stderr_ptr) |instream| {
+            *instream = io.InStream {
+                .fd = stderr_pipe[0],
+                .handle = {},
+                .handle_id = {},
+            };
+        }
+
+        *child = ChildProcess {
+            .allocator = allocator,
+            .pid = pid,
+            .err_pipe = err_pipe,
+            .llnode = LinkedList(&ChildProcess).Node.init(child),
+            .term = null,
+            .onTerm = onTerm,
+            .stdin = stdin_ptr,
+            .stdout = stdout_ptr,
+            .stderr = stderr_ptr,
+        };
+
+        children_nodes.prepend(&child.llnode);
+
+        restore_SIGCHLD();
+
         if (stdin == StdIo.Pipe) { os.posixClose(stdin_pipe[0]); }
         if (stdout == StdIo.Pipe) { os.posixClose(stdout_pipe[1]); }
         if (stderr == StdIo.Pipe) { os.posixClose(stderr_pipe[1]); }
         if (any_ignore) { os.posixClose(dev_null_fd); }
 
-        return ChildProcess {
-            .pid = i32(pid),
-            .err_pipe = err_pipe,
-
-            .stdin = if (stdin == StdIo.Pipe) {
-                io.OutStream {
-                    .fd = stdin_pipe[1],
-                    .handle = {},
-                    .handle_id = {},
-                    .buffer = undefined,
-                    .index = 0,
-                }
-            } else {
-                null
-            },
-            .stdout = if (stdout == StdIo.Pipe) {
-                io.InStream {
-                    .fd = stdout_pipe[0],
-                    .handle = {},
-                    .handle_id = {},
-                }
-            } else {
-                null
-            },
-            .stderr = if (stderr == StdIo.Pipe) {
-                io.InStream {
-                    .fd = stderr_pipe[0],
-                    .handle = {},
-                    .handle_id = {},
-                }
-            } else {
-                null
-            },
-        };
+        return child;
     }
 
     fn setUpChildIo(stdio: StdIo, pipe_fd: i32, std_fileno: i32, dev_null_fd: i32) -> %void {
@@ -258,3 +335,54 @@ fn readIntFd(fd: i32) -> %ErrInt {
     os.posixRead(fd, bytes[0..]) %% return error.SystemResources;
     return mem.readInt(bytes[0..], ErrInt, true);
 }
+
+extern fn sigchld_handler(_: i32) {
+    while (true) {
+        var status: i32 = undefined;
+        const pid_result = posix.waitpid(-1, &status, posix.WNOHANG);
+        const err = posix.getErrno(pid_result);
+        if (err == posix.ECHILD) {
+            return;
+        }
+        handleTerm(i32(pid_result), status);
+    }
+}
+
+fn handleTerm(pid: i32, status: i32) {
+    var it = children_nodes.first;
+    while (it) |node| : (it = node.next) {
+        if (node.data.pid == pid) {
+            assert(node.data.term == null);
+            node.data.handleWaitResult(status);
+            return;
+        }
+    }
+    unreachable;
+}
+
+const sigchld_set = {
+    var signal_set = posix.empty_sigset;
+    posix.sigaddset(&signal_set, posix.SIGCHLD);
+    signal_set
+};
+
+fn block_SIGCHLD() {
+    const err = posix.getErrno(posix.sigprocmask(posix.SIG_BLOCK, &sigchld_set, null));
+    assert(err == 0);
+}
+
+fn restore_SIGCHLD() {
+    const err = posix.getErrno(posix.sigprocmask(posix.SIG_UNBLOCK, &sigchld_set, null));
+    assert(err == 0);
+}
+
+const sigchld_action = posix.Sigaction {
+    .handler = sigchld_handler,
+    .mask = posix.empty_sigset,
+    .flags = posix.SA_RESTART | posix.SA_NOCLDSTOP,
+};
+
+fn install_SIGCHLD_handler() {
+    const err = posix.getErrno(posix.sigaction(posix.SIGCHLD, &sigchld_action, null));
+    assert(err == 0);
+}
std/os/linux.zig
@@ -1,3 +1,4 @@
+const assert = @import("../debug.zig").assert;
 const builtin = @import("builtin");
 const arch = switch (builtin.arch) {
     builtin.Arch.x86_64 => @import("linux_x86_64.zig"),
@@ -36,6 +37,22 @@ pub const MAP_STACK      = 0x20000;
 pub const MAP_HUGETLB    = 0x40000;
 pub const MAP_FILE       = 0;
 
+pub const WNOHANG    = 1;
+pub const WUNTRACED  = 2;
+pub const WSTOPPED   = 2;
+pub const WEXITED    = 4;
+pub const WCONTINUED = 8;
+pub const WNOWAIT    = 0x1000000;
+
+pub const SA_NOCLDSTOP  = 1;
+pub const SA_NOCLDWAIT  = 2;
+pub const SA_SIGINFO    = 4;
+pub const SA_ONSTACK    = 0x08000000;
+pub const SA_RESTART    = 0x10000000;
+pub const SA_NODEFER    = 0x40000000;
+pub const SA_RESETHAND  = 0x80000000;
+pub const SA_RESTORER   = 0x04000000;
+
 pub const SIGHUP    = 1;
 pub const SIGINT    = 2;
 pub const SIGQUIT   = 3;
@@ -100,9 +117,9 @@ pub const SEEK_SET = 0;
 pub const SEEK_CUR = 1;
 pub const SEEK_END = 2;
 
-const SIG_BLOCK   = 0;
-const SIG_UNBLOCK = 1;
-const SIG_SETMASK = 2;
+pub const SIG_BLOCK   = 0;
+pub const SIG_UNBLOCK = 1;
+pub const SIG_SETMASK = 2;
 
 pub const SOCK_STREAM = 1;
 pub const SOCK_DGRAM = 2;
@@ -448,7 +465,7 @@ pub fn getrandom(buf: &u8, count: usize, flags: u32) -> usize {
 }
 
 pub fn kill(pid: i32, sig: i32) -> usize {
-    arch.syscall2(arch.SYS_kill, usize(pid), usize(sig))
+    arch.syscall2(arch.SYS_kill, @bitCast(usize, isize(pid)), usize(sig))
 }
 
 pub fn unlink(path: &const u8) -> usize {
@@ -456,17 +473,65 @@ pub fn unlink(path: &const u8) -> usize {
 }
 
 pub fn waitpid(pid: i32, status: &i32, options: i32) -> usize {
-    arch.syscall4(arch.SYS_wait4, usize(pid), @ptrToInt(status), @bitCast(usize, isize(options)), 0)
+    arch.syscall4(arch.SYS_wait4, @bitCast(usize, isize(pid)), @ptrToInt(status), @bitCast(usize, isize(options)), 0)
 }
 
 pub fn nanosleep(req: &const timespec, rem: ?&timespec) -> usize {
     arch.syscall2(arch.SYS_nanosleep, @ptrToInt(req), @ptrToInt(rem))
 }
 
+pub fn sigprocmask(flags: u32, set: &const sigset_t, oldset: ?&sigset_t) -> usize {
+    arch.syscall4(arch.SYS_rt_sigprocmask, flags, @ptrToInt(set), @ptrToInt(oldset), NSIG/8)
+}
+
+pub fn sigaction(sig: u6, noalias act: &const Sigaction, noalias oact: ?&Sigaction) -> usize {
+    assert(sig >= 1);
+    assert(sig != SIGKILL);
+    assert(sig != SIGSTOP);
+    var ksa = k_sigaction {
+        .handler = act.handler,
+        .flags = act.flags | SA_RESTORER,
+        .mask = undefined,
+        .restorer = @ptrCast(extern fn(), arch.restore_rt),
+    };
+    var ksa_old: k_sigaction = undefined;
+    @memcpy(@ptrCast(&u8, &ksa.mask), @ptrCast(&const u8, &act.mask), 8);
+    const result = arch.syscall4(arch.SYS_rt_sigaction, sig, @ptrToInt(&ksa), @ptrToInt(&ksa_old), @sizeOf(@typeOf(ksa.mask)));
+    const err = getErrno(result);
+    if (err != 0) {
+        return result;
+    }
+    if (oact) |old| {
+        old.handler = ksa_old.handler;
+        old.flags = @truncate(u32, ksa_old.flags);
+        @memcpy(@ptrCast(&u8, &old.mask), @ptrCast(&const u8, &ksa_old.mask), @sizeOf(@typeOf(ksa_old.mask)));
+    }
+    return 0;
+}
+
 const NSIG = 65;
-const sigset_t = [128]u8;
-const all_mask = []u8 { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, };
-const app_mask = []u8 { 0xff, 0xff, 0xff, 0xfc, 0x7f, 0xff, 0xff, 0xff, };
+const sigset_t = [128 / @sizeOf(usize)]usize;
+const all_mask = []usize{@maxValue(usize)};
+const app_mask = []usize{0xfffffffc7fffffff};
+
+const k_sigaction = extern struct {
+    handler: extern fn(i32),
+    flags: usize,
+    restorer: extern fn(),
+    mask: [2]u32,
+};
+
+/// Renamed from `sigaction` to `Sigaction` to avoid conflict with the syscall.
+pub const Sigaction = struct {
+    handler: extern fn(i32),
+    mask: sigset_t,
+    flags: u32,
+};
+
+pub const SIG_ERR = @intToPtr(extern fn(i32), @maxValue(usize));
+pub const SIG_DFL = @intToPtr(extern fn(i32), 0);
+pub const SIG_IGN = @intToPtr(extern fn(i32), 1);
+pub const empty_sigset = []usize{0} ** sigset_t.len;
 
 pub fn raise(sig: i32) -> usize {
     var set: sigset_t = undefined;
@@ -489,6 +554,16 @@ fn restoreSignals(set: &sigset_t) {
     _ = arch.syscall4(arch.SYS_rt_sigprocmask, SIG_SETMASK, @ptrToInt(set), 0, NSIG/8);
 }
 
+pub fn sigaddset(set: &sigset_t, sig: u6) {
+    const s = sig - 1;
+    (*set)[usize(s) / usize.bit_count] |= usize(1) << (s & (usize.bit_count - 1));
+}
+
+pub fn sigismember(set: &const sigset_t, sig: u6) -> bool {
+    const s = sig - 1;
+    return ((*set)[usize(s) / usize.bit_count] & (usize(1) << (s & (usize.bit_count - 1)))) != 0;
+}
+
 
 pub const sa_family_t = u16;
 pub const socklen_t = u32;
std/os/linux_i386.zig
@@ -486,6 +486,23 @@ pub inline fn syscall6(number: usize, arg1: usize, arg2: usize, arg3: usize,
             [arg6] "{ebp}" (arg6))
 }
 
+pub nakedcc fn restore() {
+    asm volatile (
+        \\popl %%eax
+        \\movl $119, %%eax
+        \\int $0x80
+        :
+        :
+        : "rcx", "r11")
+}
+
+pub nakedcc fn restore_rt() {
+    asm volatile ("int $0x80"
+        :
+        : [number] "{eax}" (usize(SYS_rt_sigreturn))
+        : "rcx", "r11")
+}
+
 export struct msghdr {
     msg_name: &u8,
     msg_namelen: socklen_t,
std/os/linux_x86_64.zig
@@ -442,6 +442,14 @@ pub fn syscall6(number: usize, arg1: usize, arg2: usize, arg3: usize, arg4: usiz
         : "rcx", "r11")
 }
 
+pub nakedcc fn restore_rt() {
+    asm volatile ("syscall"
+        :
+        : [number] "{rax}" (usize(SYS_rt_sigreturn))
+        : "rcx", "r11")
+}
+
+
 pub const msghdr = extern struct {
     msg_name: &u8,
     msg_namelen: socklen_t,
std/build.zig
@@ -545,7 +545,7 @@ pub const Builder = struct {
         }
 
         var child = os.ChildProcess.spawn(exe_path, args, cwd, env_map,
-            StdIo.Inherit, StdIo.Inherit, StdIo.Inherit, self.allocator) %% |err|
+            StdIo.Inherit, StdIo.Inherit, StdIo.Inherit, null, self.allocator) %% |err|
         {
             %%io.stderr.printf("Unable to spawn {}: {}\n", exe_path, @errorName(err));
             return err;
@@ -556,7 +556,7 @@ pub const Builder = struct {
             return err;
         };
         switch (term) {
-            Term.Clean => |code| {
+            Term.Exited => |code| {
                 if (code != 0) {
                     %%io.stderr.printf("Process {} exited with error code {}\n", exe_path, code);
                     return error.UncleanExit;
std/linked_list.zig
@@ -1,7 +1,6 @@
 const debug = @import("debug.zig");
 const assert = debug.assert;
 const mem = @import("mem.zig");
-const Allocator = mem.Allocator;
 
 /// Generic doubly linked list.
 pub fn LinkedList(comptime T: type) -> type {
@@ -13,26 +12,29 @@ pub fn LinkedList(comptime T: type) -> type {
             prev: ?&Node,
             next: ?&Node,
             data: T,
+
+            pub fn init(data: &const T) -> Node {
+                Node {
+                    .data = *data,
+                    .prev = null,
+                    .next = null,
+                }
+            }
         };
 
         first: ?&Node,
         last:  ?&Node,
         len:   usize,
-        allocator: &Allocator,
 
         /// Initialize a linked list.
         ///
-        /// Arguments:
-        ///     allocator: Dynamic memory allocator.
-        ///
         /// Returns:
         ///     An empty linked list.
-        pub fn init(allocator: &Allocator) -> Self {
+        pub fn init() -> Self {
             Self {
                 .first = null,
                 .last  = null,
                 .len   = 0,
-                .allocator = allocator,
             }
         }
 
@@ -155,55 +157,38 @@ pub fn LinkedList(comptime T: type) -> type {
             return first;
         }
 
-        /// Allocate a new node.
-        ///
-        /// Returns:
-        ///     A pointer to the new node.
-        pub fn allocateNode(list: &Self) -> %&Node {
-            list.allocator.create(Node)
-        }
+    }
+}
 
-        /// Deallocate a node.
-        ///
-        /// Arguments:
-        ///     node: Pointer to the node to deallocate.
-        pub fn destroyNode(list: &Self, node: &Node) {
-            list.allocator.destroy(node);
-        }
+pub fn testAllocateNode(comptime T: type, list: &LinkedList(T), allocator: &mem.Allocator) -> %&LinkedList(T).Node {
+    allocator.create(LinkedList(T).Node)
+}
 
-        /// Allocate and initialize a node and its data.
-        ///
-        /// Arguments:
-        ///     data: The data to put inside the node.
-        ///
-        /// Returns:
-        ///     A pointer to the new node.
-        pub fn createNode(list: &Self, data: &const T) -> %&Node {
-            var node = %return list.allocateNode();
-            *node = Node {
-                .prev = null,
-                .next = null,
-                .data = *data,
-            };
-            return node;
-        }
-    }
+pub fn testDestroyNode(comptime T: type, list: &LinkedList(T), node: &LinkedList(T).Node, allocator: &mem.Allocator) {
+    allocator.destroy(node);
 }
 
-test "basic linked list test" {
-    var list = LinkedList(u32).init(&debug.global_allocator);
+pub fn testCreateNode(comptime T: type, list: &LinkedList(T), data: &const T, allocator: &mem.Allocator) -> %&LinkedList(T).Node {
+    var node = %return testAllocateNode(T, list, allocator);
+    *node = LinkedList(T).Node.init(data);
+    return node;
+}
 
-    var one   = %%list.createNode(1);
-    var two   = %%list.createNode(2);
-    var three = %%list.createNode(3);
-    var four  = %%list.createNode(4);
-    var five  = %%list.createNode(5);
+test "basic linked list test" {
+    const allocator = &debug.global_allocator;
+    var list = LinkedList(u32).init();
+
+    var one   = %%testCreateNode(u32, &list, 1, allocator);
+    var two   = %%testCreateNode(u32, &list, 2, allocator);
+    var three = %%testCreateNode(u32, &list, 3, allocator);
+    var four  = %%testCreateNode(u32, &list, 4, allocator);
+    var five  = %%testCreateNode(u32, &list, 5, allocator);
     defer {
-        list.destroyNode(one);
-        list.destroyNode(two);
-        list.destroyNode(three);
-        list.destroyNode(four);
-        list.destroyNode(five);
+        testDestroyNode(u32, &list, one, allocator);
+        testDestroyNode(u32, &list, two, allocator);
+        testDestroyNode(u32, &list, three, allocator);
+        testDestroyNode(u32, &list, four, allocator);
+        testDestroyNode(u32, &list, five, allocator);
     }
 
     list.append(two);               // {2}
std/mem.zig
@@ -49,11 +49,16 @@ pub const Allocator = struct {
     }
 
     fn free(self: &Allocator, memory: var) {
-        const const_slice = ([]const u8)(memory);
-        if (memory.len == 0)
-            return;
-        const ptr = @intToPtr(&u8, @ptrToInt(const_slice.ptr));
-        self.freeFn(self, ptr);
+        const ptr = if (@typeId(@typeOf(memory)) == builtin.TypeId.Pointer) {
+            memory
+        } else {
+            const const_slice = ([]const u8)(memory);
+            if (memory.len == 0)
+                return;
+            const_slice.ptr
+        };
+        const non_const_ptr = @intToPtr(&u8, @ptrToInt(ptr));
+        self.freeFn(self, non_const_ptr);
     }
 };
 
test/cases/array.zig
@@ -86,3 +86,13 @@ test "array literal with specified size" {
     assert(array[0] == 1);
     assert(array[1] == 2);
 }
+
+test "array child property" {
+    var x: [5]i32 = undefined;
+    assert(@typeOf(x).child == i32);
+}
+
+test "array len property" {
+    var x: [5]i32 = undefined;
+    assert(@typeOf(x).len == 5);
+}
test/tests.zig
@@ -238,7 +238,7 @@ pub const CompareOutputContext = struct {
             %%io.stderr.printf("Test {}/{} {}...", self.test_index+1, self.context.test_index, self.name);
 
             var child = os.ChildProcess.spawn(full_exe_path, [][]u8{}, null, &b.env_map,
-                StdIo.Ignore, StdIo.Pipe, StdIo.Pipe, b.allocator) %% |err|
+                StdIo.Ignore, StdIo.Pipe, StdIo.Pipe, null, b.allocator) %% |err|
             {
                 debug.panic("Unable to spawn {}: {}\n", full_exe_path, @errorName(err));
             };
@@ -253,7 +253,7 @@ pub const CompareOutputContext = struct {
                 debug.panic("Unable to spawn {}: {}\n", full_exe_path, @errorName(err));
             };
             switch (term) {
-                Term.Clean => |code| {
+                Term.Exited => |code| {
                     if (code != 0) {
                         %%io.stderr.printf("Process {} exited with error code {}\n", full_exe_path, code);
                         return error.TestFailed;
@@ -313,7 +313,7 @@ pub const CompareOutputContext = struct {
             %%io.stderr.printf("Test {}/{} {}...", self.test_index+1, self.context.test_index, self.name);
 
             var child = os.ChildProcess.spawn(full_exe_path, [][]u8{}, null, &b.env_map,
-                StdIo.Ignore, StdIo.Pipe, StdIo.Pipe, b.allocator) %% |err|
+                StdIo.Ignore, StdIo.Pipe, StdIo.Pipe, null, b.allocator) %% |err|
             {
                 debug.panic("Unable to spawn {}: {}\n", full_exe_path, @errorName(err));
             };
@@ -324,7 +324,7 @@ pub const CompareOutputContext = struct {
 
             const debug_trap_signal: i32 = 5;
             switch (term) {
-                Term.Clean => |code| {
+                Term.Exited => |code| {
                     %%io.stderr.printf("\nProgram expected to hit debug trap (signal {}) " ++
                         "but exited with return code {}\n", debug_trap_signal, code);
                     return error.TestFailed;
@@ -557,7 +557,7 @@ pub const CompileErrorContext = struct {
             }
 
             var child = os.ChildProcess.spawn(b.zig_exe, zig_args.toSliceConst(), null, &b.env_map,
-                StdIo.Ignore, StdIo.Pipe, StdIo.Pipe, b.allocator) %% |err|
+                StdIo.Ignore, StdIo.Pipe, StdIo.Pipe, null, b.allocator) %% |err|
             {
                 debug.panic("Unable to spawn {}: {}\n", b.zig_exe, @errorName(err));
             };
@@ -572,7 +572,7 @@ pub const CompileErrorContext = struct {
                 debug.panic("Unable to spawn {}: {}\n", b.zig_exe, @errorName(err));
             };
             switch (term) {
-                Term.Clean => |code| {
+                Term.Exited => |code| {
                     if (code == 0) {
                         %%io.stderr.printf("Compilation incorrectly succeeded\n");
                         return error.TestFailed;
@@ -819,7 +819,7 @@ pub const ParseCContext = struct {
             }
 
             var child = os.ChildProcess.spawn(b.zig_exe, zig_args.toSliceConst(), null, &b.env_map,
-                StdIo.Ignore, StdIo.Pipe, StdIo.Pipe, b.allocator) %% |err|
+                StdIo.Ignore, StdIo.Pipe, StdIo.Pipe, null, b.allocator) %% |err|
             {
                 debug.panic("Unable to spawn {}: {}\n", b.zig_exe, @errorName(err));
             };
@@ -834,7 +834,7 @@ pub const ParseCContext = struct {
                 debug.panic("Unable to spawn {}: {}\n", b.zig_exe, @errorName(err));
             };
             switch (term) {
-                Term.Clean => |code| {
+                Term.Exited => |code| {
                     if (code != 0) {
                         %%io.stderr.printf("Compilation failed with exit code {}\n", code);
                         return error.TestFailed;