terminal-util: introduce openpt_allocate()

Allocating a pty is done in a couple of places so let's introduce a new helper
which does the job.

Also the new function, as well as openpt_in_namespace(), returns both pty
master and slave so the callers don't need to know about the pty slave
allocation details.

For the same reasons machine_openpt() prototype has also been changed to return
both pty master and slave so callers don't need to allocate a pty slave which
might be in a different namespace.

Finally openpt_in_namespace() has been renamed into
openpt_allocate_in_namespace().

src/machine/machine-dbus.c

@@ -423,14 +423,10 @@ int bus_machine_method_open_pty(sd_bus_message *message, void *userdata, sd_bus_
         if (r == 0)
                 return 1; /* Will call us back */
 
-        master = machine_openpt(m, O_RDWR|O_NOCTTY|O_CLOEXEC);
+        master = machine_openpt(m, O_RDWR|O_NOCTTY|O_CLOEXEC, &pty_name);
         if (master < 0)
                 return master;
 
-        r = ptsname_namespace(master, &pty_name);
-        if (r < 0)
-                return r;
-
         r = sd_bus_message_new_method_return(message, &reply);
         if (r < 0)
                 return r;
@@ -514,17 +510,12 @@ int bus_machine_method_open_login(sd_bus_message *message, void *userdata, sd_bu
         if (r == 0)
                 return 1; /* Will call us back */
 
-        master = machine_openpt(m, O_RDWR|O_NOCTTY|O_CLOEXEC);
+        master = machine_openpt(m, O_RDWR|O_NOCTTY|O_CLOEXEC, &pty_name);
         if (master < 0)
                 return master;
 
-        r = ptsname_namespace(master, &pty_name);
-        if (r < 0)
-                return r;
-
         p = path_startswith(pty_name, "/dev/pts/");
-        if (!p)
-                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "PTS name %s is invalid", pty_name);
+        assert(p);
 
         r = container_bus_new(m, error, &allocated_bus);
         if (r < 0)
@@ -630,14 +621,10 @@ int bus_machine_method_open_shell(sd_bus_message *message, void *userdata, sd_bu
         if (r == 0)
                 return 1; /* Will call us back */
 
-        master = machine_openpt(m, O_RDWR|O_NOCTTY|O_CLOEXEC);
+        master = machine_openpt(m, O_RDWR|O_NOCTTY|O_CLOEXEC, &pty_name);
         if (master < 0)
                 return master;
 
-        r = ptsname_namespace(master, &pty_name);
-        if (r < 0)
-                return r;
-
         p = path_startswith(pty_name, "/dev/pts/");
         assert(p);
 

src/machine/machine.c

@@ -530,29 +530,20 @@ int machine_kill(Machine *m, KillWho who, int signo) {
         return manager_kill_unit(m->manager, m->unit, signo, NULL);
 }
 
-int machine_openpt(Machine *m, int flags) {
+int machine_openpt(Machine *m, int flags, char **ret_slave) {
         assert(m);
 
         switch (m->class) {
 
-        case MACHINE_HOST: {
-                int fd;
+        case MACHINE_HOST:
 
-                fd = posix_openpt(flags);
-                if (fd < 0)
-                        return -errno;
-
-                if (unlockpt(fd) < 0)
-                        return -errno;
-
-                return fd;
-        }
+                return openpt_allocate(flags, ret_slave);
 
         case MACHINE_CONTAINER:
                 if (m->leader <= 0)
                         return -EINVAL;
 
-                return openpt_in_namespace(m->leader, flags);
+                return openpt_allocate_in_namespace(m->leader, flags, ret_slave);
 
         default:
                 return -EOPNOTSUPP;

src/machine/machine.h

@@ -89,7 +89,7 @@ MachineState machine_state_from_string(const char *s) _pure_;
 const char *kill_who_to_string(KillWho k) _const_;
 KillWho kill_who_from_string(const char *s) _pure_;
 
-int machine_openpt(Machine *m, int flags);
+int machine_openpt(Machine *m, int flags, char **ret_slave);
 int machine_open_terminal(Machine *m, const char *path, int mode);
 
 int machine_get_uid_shift(Machine *m, uid_t *ret);