bunpen: pasta setup (ip ...): never outlive parent bunpen instance

pkgs/by-name/bunpen/restrict/ns/multiprocess.ha

@@ -8,6 +8,7 @@ use log;
 use os;
 use os::exec;
 use rt;
+use rt::ext;
 use unix::signal;
 
 // fork and:
@@ -65,6 +66,51 @@ fn wait_and_propagate(child_pid: os::exec::process) (void | os::exec::error) = {
   os::exit(rc);  // propagate exit code
 };
 
+// run the provided command in a new process, and wait for its return.
+// under the hood:
+// 1. fork
+// 2. in child: execvpe
+// 3. in parent: wait for child
+export fn shellvpe(name: str, argv: []str, envp: []str = []) (os::exec::status | os::exec::error | rt::errno) = {
+  return match (fork_and_die_with_parent()?) {
+    case void =>
+      errors::ext::check("shellvpe", rt::ext::execvpe(name, argv, envp));
+      assert(false, "unreachable");
+      return os::exec::status { ... };
+    case let child_pid: os::exec::process =>
+      yield wait_child(child_pid);
+  };
+};
+
+// same as `shellvpe(name, argv, envp)` but fallback to `name=default` if `name`
+// isn't found on PATH
+export fn shellvpe_or_default(default: str, name: str, argv: []str, envp: []str = []) (os::exec::status | os::exec::error | rt::errno) = {
+  return match (fork_and_die_with_parent()?) {
+    case void =>
+      errors::ext::check("shellvpe", rt::ext::execvpe_or_default(default, name, argv, envp));
+      assert(false, "unreachable");
+      return os::exec::status { ... };
+    case let child_pid: os::exec::process =>
+      yield wait_child(child_pid);
+  };
+};
+
+// fn wait_child(child_pid: os::exec::process) (os::exec::status | os::exec::error) = {
+//   for (true) {
+//     match (os::exec::wait(&child_pid)) {
+//       case let e: os::exec::error => match (e) {
+//         case errors::interrupted =>
+//           // i guess before the days of `poll`, `wait` had to wait on either the
+//           // child OR a signal sent to this pid; so we need to retry if the
+//           // reason we woke isn't because the child died...
+//           void;
+//         case => return e;
+//       };
+//       case let status: os::exec::status => return status;
+//     };
+//   };
+// };
+
 // block until the provided child exits, and then return its exit status.
 // this function actually waits on *any* child, in a loop, but only returns the
 // exit code for the specific child of interest.

pkgs/by-name/bunpen/restrict/ns/pasta.ha

@@ -123,7 +123,7 @@ fn config_routing_in_ns(net: restrict::net_subset) (void | os::exec::error | rt:
   // forward dns to the desired endpoint
   let dnsdest = fmt::asprintf("{}:53", net.dns);
   defer free(dnsdest);
-  let rc = rt::ext::shellvpe_or_default(
+  let rc = shellvpe_or_default(
     config::IPTABLES,
     "iptables",
     [
@@ -147,7 +147,7 @@ fn config_routing_in_ns(net: restrict::net_subset) (void | os::exec::error | rt:
   // therefore, set it up *now*, and delete the addrs, and then since it's
   // already up they won't re-appear when we exec pasta.
 
-  let rc = rt::ext::shellvpe_or_default(
+  let rc = shellvpe_or_default(
     config::IP,
     "ip",
     [
@@ -159,7 +159,7 @@ fn config_routing_in_ns(net: restrict::net_subset) (void | os::exec::error | rt:
   )?;
   log::printfln("[namespace/pasta] 'ip link set lo up' exited {}", rc.status);
 
-  let rc = rt::ext::shellvpe_or_default(
+  let rc = shellvpe_or_default(
     config::IP,
     "ip",
     [

pkgs/by-name/bunpen/rt/ext/exec.ha

@@ -47,51 +47,6 @@ export fn execvpe_or_default(default: str, name: str, argv: []str, envp: []str =
   };
 };
 
-// run the provided command in a new process, and wait for its return.
-// under the hood:
-// 1. fork
-// 2. in child: execvpe
-// 3. in parent: wait for child
-export fn shellvpe(name: str, argv: []str, envp: []str = []) (os::exec::status | os::exec::error) = {
-  return match (os::exec::fork()) {
-    case void =>
-      errors::ext::check("shellvpe", execvpe(name, argv, envp));
-      assert(false, "unreachable");
-      return os::exec::status { ... };
-    case let child_pid: os::exec::process =>
-      yield wait_child(child_pid);
-  };
-};
-
-// same as `shellvpe(name, argv, envp)` but fallback to `name=default` if `name`
-// isn't found on PATH
-export fn shellvpe_or_default(default: str, name: str, argv: []str, envp: []str = []) (os::exec::status | os::exec::error) = {
-  return match (os::exec::fork()) {
-    case void =>
-      errors::ext::check("shellvpe", execvpe_or_default(default, name, argv, envp));
-      assert(false, "unreachable");
-      return os::exec::status { ... };
-    case let child_pid: os::exec::process =>
-      yield wait_child(child_pid);
-  };
-};
-
-fn wait_child(child_pid: os::exec::process) (os::exec::status | os::exec::error) = {
-  for (true) {
-    match (os::exec::wait(&child_pid)) {
-      case let e: os::exec::error => match (e) {
-        case errors::interrupted =>
-          // i guess before the days of `poll`, `wait` had to wait on either the
-          // child OR a signal sent to this pid; so we need to retry if the
-          // reason we woke isn't because the child died...
-          void;
-        case => return e;
-      };
-      case let status: os::exec::status => return status;
-    };
-  };
-};
-
 // allocate and return a NULL-terminated array of pointers to c strings.
 // caller is responsible for free'ing the resulting array AND its strings.
 fn to_cstr_array(strs: []str) []nullable *const c::char = {