Allow setting PGID in std.process.Child.spawn

lib/std/c.zig

@@ -9167,6 +9167,7 @@ pub extern "c" fn setreuid(ruid: uid_t, euid: uid_t) c_int;
 pub extern "c" fn setregid(rgid: gid_t, egid: gid_t) c_int;
 pub extern "c" fn setresuid(ruid: uid_t, euid: uid_t, suid: uid_t) c_int;
 pub extern "c" fn setresgid(rgid: gid_t, egid: gid_t, sgid: gid_t) c_int;
+pub extern "c" fn setpgid(pid: pid_t, pgid: pid_t) c_int;
 
 pub extern "c" fn malloc(usize) ?*anyopaque;
 pub extern "c" fn realloc(?*anyopaque, usize) ?*anyopaque;

lib/std/os/linux.zig

@@ -1551,6 +1551,10 @@ pub fn setresgid(rgid: gid_t, egid: gid_t, sgid: gid_t) usize {
     }
 }
 
+pub fn setpgid(pid: pid_t, pgid: pid_t) usize {
+    return syscall2(.setpgid, @intCast(pid), @intCast(pgid));
+}
+
 pub fn getgroups(size: usize, list: *gid_t) usize {
     if (@hasField(SYS, "getgroups32")) {
         return syscall2(.getgroups32, size, @intFromPtr(list));

lib/std/posix.zig

@@ -3415,6 +3415,24 @@ pub fn setregid(rgid: gid_t, egid: gid_t) SetIdError!void {
     }
 }
 
+pub const SetPgidError = error{
+    ProcessAlreadyExec,
+    InvalidProcessGroupId,
+    PermissionDenied,
+    ProcessNotFound,
+} || UnexpectedError;
+
+pub fn setpgid(pid: pid_t, pgid: pid_t) SetPgidError!void {
+    switch (errno(system.setpgid(pid, pgid))) {
+        .SUCCESS => return,
+        .ACCES => return error.ProcessAlreadyExec,
+        .INVAL => return error.InvalidProcessGroupId,
+        .PERM => return error.PermissionDenied,
+        .SRCH => return error.ProcessNotFound,
+        else => |err| return unexpectedErrno(err),
+    }
+}
+
 /// Test whether a file descriptor refers to a terminal.
 pub fn isatty(handle: fd_t) bool {
     if (native_os == .windows) {

lib/std/process/Child.zig

@@ -63,6 +63,9 @@ uid: if (native_os == .windows or native_os == .wasi) void else ?posix.uid_t,
 /// Set to change the group id when spawning the child process.
 gid: if (native_os == .windows or native_os == .wasi) void else ?posix.gid_t,
 
+/// Set to change the process group id when spawning the child process.
+pgid: if (native_os == .windows or native_os == .wasi) void else ?posix.pid_t,
+
 /// Set to change the current working directory when spawning the child process.
 cwd: ?[]const u8,
 /// Set to change the current working directory when spawning the child process.
@@ -168,6 +171,7 @@ pub const SpawnError = error{
 } ||
     posix.ExecveError ||
     posix.SetIdError ||
+    posix.SetPgidError ||
     posix.ChangeCurDirError ||
     windows.CreateProcessError ||
     windows.GetProcessMemoryInfoError ||
@@ -213,6 +217,7 @@ pub fn init(argv: []const []const u8, allocator: mem.Allocator) ChildProcess {
         .cwd = null,
         .uid = if (native_os == .windows or native_os == .wasi) {} else null,
         .gid = if (native_os == .windows or native_os == .wasi) {} else null,
+        .pgid = if (native_os == .windows or native_os == .wasi) {} else null,
         .stdin = null,
         .stdout = null,
         .stderr = null,
@@ -675,6 +680,10 @@ fn spawnPosix(self: *ChildProcess) SpawnError!void {
             posix.setreuid(uid, uid) catch |err| forkChildErrReport(err_pipe[1], err);
         }
 
+        if (self.pgid) |pid| {
+            posix.setpgid(0, pid) catch |err| forkChildErrReport(err_pipe[1], err);
+        }
+
         const err = switch (self.expand_arg0) {
             .expand => posix.execvpeZ_expandArg0(.expand, argv_buf.ptr[0].?, argv_buf.ptr, envp),
             .no_expand => posix.execvpeZ_expandArg0(.no_expand, argv_buf.ptr[0].?, argv_buf.ptr, envp),