remove posix exposure in child_process

reason: nobody came up with a use case yet

Author: matu3ba

lib/std/child_process.zig

@@ -57,12 +57,6 @@ pub const ChildProcess = struct {
 
     expand_arg0: Arg0Expand,
 
-    /// Use this for additional posix spawn attributes.
-    /// Do not set spawn attribute flags and do not modify stdin, stdout, stderr
-    /// behavior, because those are set in the platform-specific spawn method.
-    posix_attr: if (os.hasPosixSpawn) ?os.posix_spawn.Attr else void,
-    posix_actions: if (os.hasPosixSpawn) ?os.posix_spawn.Actions else void,
-
     /// Darwin-only. Disable ASLR for the child process.
     disable_aslr: bool = false,
 
@@ -132,8 +126,6 @@ pub const ChildProcess = struct {
             .stdout_behavior = StdIo.Inherit,
             .stderr_behavior = StdIo.Inherit,
             .expand_arg0 = .no_expand,
-            .posix_attr = if (os.hasPosixSpawn) null else undefined,
-            .posix_actions = if (os.hasPosixSpawn) null else undefined,
         };
     }
 
@@ -149,7 +141,7 @@ pub const ChildProcess = struct {
             @compileError("the target operating system cannot spawn processes");
         }
 
-        if (os.hasPosixSpawn) {
+        if (comptime builtin.target.isDarwin()) {
             return self.spawnMacos();
         }
 
@@ -481,7 +473,7 @@ pub const ChildProcess = struct {
     }
 
     fn waitUnwrapped(self: *ChildProcess) !void {
-        const res: os.WaitPidResult = if (os.hasPosixSpawn)
+        const res: os.WaitPidResult = if (comptime builtin.target.isDarwin())
             try os.posix_spawn.waitpid(self.pid, 0)
         else
             os.waitpid(self.pid, 0);
@@ -561,10 +553,6 @@ pub const ChildProcess = struct {
     }
 
     fn spawnMacos(self: *ChildProcess) SpawnError!void {
-        // dont cleanup structure owned == initialized by user
-        const user_attr: bool = self.posix_attr != null;
-        const user_actions: bool = self.posix_actions != null;
-
         const pipe_flags = if (io.is_async) os.O.NONBLOCK else 0;
         const stdin_pipe = if (self.stdin_behavior == StdIo.Pipe) try os.pipe2(pipe_flags) else undefined;
         errdefer if (self.stdin_behavior == StdIo.Pipe) destroyPipe(stdin_pipe);
@@ -592,28 +580,28 @@ pub const ChildProcess = struct {
             undefined;
         defer if (any_ignore) os.close(dev_null_fd);
 
-        if (user_attr == false) self.posix_attr = try os.posix_spawn.Attr.init();
-        defer if (user_attr == false) self.posix_attr.?.deinit();
+        var attr = try os.posix_spawn.Attr.init();
+        defer attr.deinit();
         var flags: u16 = os.darwin.POSIX_SPAWN_SETSIGDEF | os.darwin.POSIX_SPAWN_SETSIGMASK;
         if (self.disable_aslr) {
             flags |= os.darwin._POSIX_SPAWN_DISABLE_ASLR;
         }
         if (self.start_suspended) {
             flags |= os.darwin.POSIX_SPAWN_START_SUSPENDED;
         }
-        try self.posix_attr.?.set(flags);
+        try attr.set(flags);
 
-        if (user_actions == false) self.posix_actions = try os.posix_spawn.Actions.init();
-        defer if (user_actions == false) self.posix_actions.?.deinit();
+        var actions = try os.posix_spawn.Actions.init();
+        defer actions.deinit();
 
-        try setUpChildIoPosixSpawn(self.stdin_behavior, &self.posix_actions.?, stdin_pipe, os.STDIN_FILENO, dev_null_fd);
-        try setUpChildIoPosixSpawn(self.stdout_behavior, &self.posix_actions.?, stdout_pipe, os.STDOUT_FILENO, dev_null_fd);
-        try setUpChildIoPosixSpawn(self.stderr_behavior, &self.posix_actions.?, stderr_pipe, os.STDERR_FILENO, dev_null_fd);
+        try setUpChildIoPosixSpawn(self.stdin_behavior, &actions, stdin_pipe, os.STDIN_FILENO, dev_null_fd);
+        try setUpChildIoPosixSpawn(self.stdout_behavior, &actions, stdout_pipe, os.STDOUT_FILENO, dev_null_fd);
+        try setUpChildIoPosixSpawn(self.stderr_behavior, &actions, stderr_pipe, os.STDERR_FILENO, dev_null_fd);
 
         if (self.cwd_dir) |cwd| {
-            try self.posix_actions.?.fchdir(cwd.fd);
+            try actions.fchdir(cwd.fd);
         } else if (self.cwd) |cwd| {
-            try self.posix_actions.?.chdir(cwd);
+            try actions.chdir(cwd);
         }
 
         var arena_allocator = std.heap.ArenaAllocator.init(self.allocator);
@@ -628,7 +616,7 @@ pub const ChildProcess = struct {
             break :m envp_buf.ptr;
         } else std.c.environ;
 
-        const pid = try os.posix_spawn.spawnp(self.argv[0], self.posix_actions.?, self.posix_attr.?, argv_buf, envp);
+        const pid = try os.posix_spawn.spawnp(self.argv[0], actions, attr, argv_buf, envp);
 
         if (self.stdin_behavior == StdIo.Pipe) {
             self.stdin = File{ .handle = stdin_pipe[1] };

lib/std/os.zig

@@ -44,8 +44,6 @@ pub const windows = @import("os/windows.zig");
 pub const posix_spawn = @import("os/posix_spawn.zig");
 pub const ptrace = @import("os/ptrace.zig");
 
-// Zig support for posix spawn on the platform
-pub const hasPosixSpawn = builtin.target.isDarwin();
 /// Pipe read side
 pub const pipe_rd = 0;
 /// Pipe write side

test/standalone/childprocess_extrapipe/child.zig

@@ -11,8 +11,7 @@ pub fn main() !void {
     _ = it.next() orelse unreachable; // skip binary name
     const s_handle = it.next() orelse unreachable;
     var file_handle = try std.os.stringToHandle(s_handle);
-    // TODO: Is there a way on Windows to let the Kernel disable inheritance
-    // after it is inherited in CreateProcess???
+
     if (builtin.target.os.tag == .windows) {
         // windows.HANDLE_FLAG_INHERIT is enabled
         var handle_flags: windows.DWORD = undefined;

test/standalone/childprocess_extrapipe/parent.zig

@@ -32,14 +32,6 @@ pub fn main() !void {
     // enabling of file inheritance directly before and closing directly after spawn
     // less time to leak => better
     {
-        // Besides being faster to spawn, posix_spawn enables to close pipe[pipe_wr]
-        // within the child before it is closed from Kernel after execv.
-        // Note, that posix_spawn is executed in the child, so it does not allow
-        // to minimize the leaking time of the parent's handle side.
-        if (os.hasPosixSpawn) child_proc.posix_actions = try os.posix_spawn.Actions.init();
-        defer if (os.hasPosixSpawn) child_proc.posix_actions.?.deinit();
-        if (os.hasPosixSpawn) try child_proc.posix_actions.?.close(pipe[pipe_wr]);
-
         try os.enableInheritance(pipe[pipe_rd]);
         defer os.close(pipe[pipe_rd]);