OS-???? [lx] SIGEV_THREAD_ID emulation needed

*** 23,35 ****
--- 23,39 ----
   * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   * Copyright 2015 Joyent, Inc.
   */
  
+ #include <sys/syscall.h>
+ 
  #include <errno.h>
+ #include <stdlib.h>
  #include <string.h>
  #include <time.h>
+ #include <unistd.h>
  #include <sys/resource.h>
  #include <sys/lx_misc.h>
  #include <sys/lx_syscall.h>
  #include <lx_signum.h>
  
*** 111,124 ****
  static int ltos_sigev[] = {
          SIGEV_SIGNAL,
          SIGEV_NONE,
          SIGEV_THREAD,
          0,              /* Linux skips event 3 */
!         SIGEV_THREAD    /* the Linux SIGEV_THREAD_ID */
  };
  
  #define LX_SIGEV_MAX    (sizeof (ltos_sigev) / sizeof (ltos_sigev[0]))
  
  long
  lx_clock_nanosleep(int clock, int flags, struct timespec *rqtp,
      struct timespec *rmtp)
  {
--- 115,129 ----
  static int ltos_sigev[] = {
          SIGEV_SIGNAL,
          SIGEV_NONE,
          SIGEV_THREAD,
          0,              /* Linux skips event 3 */
!         SIGEV_THREAD    /* Linux SIGEV_THREAD_ID -- see lx_sigev_thread_id() */
  };
  
  #define LX_SIGEV_MAX            (sizeof (ltos_sigev) / sizeof (ltos_sigev[0]))
+ #define LX_SIGEV_THREAD_ID      4
  
  long
  lx_clock_nanosleep(int clock, int flags, struct timespec *rqtp,
      struct timespec *rmtp)
  {
*** 161,170 ****
--- 166,191 ----
  {
          return (-EPERM);
  }
  
  /*
+  * Notification function for use with native SIGEV_THREAD in order to
+  * emulate Linux SIGEV_THREAD_ID. Native SIGEV_THREAD is used as the
+  * timer mechanism and B_SIGEV_THREAD_ID performs the actual event
+  * delivery to the appropriate lx tid.
+  */
+ static void
+ lx_sigev_thread_id(union sigval sival)
+ {
+         lx_sigevent_t *lev = (lx_sigevent_t *)sival.sival_ptr;
+         syscall(SYS_brand, B_SIGEV_THREAD_ID, lev->lx_sigev_un.lx_tid,
+             lev->lx_sigev_signo, lev->lx_sigev_value);
+         free(lev);
+ }
+ 
+ 
+ /*
   * The Illumos timer_create man page says it accepts the following clocks:
   *   CLOCK_REALTIME (3) wall clock
   *   CLOCK_VIRTUAL (1)  user CPU usage clock - No Backend
   *   CLOCK_PROF (2)     user and system CPU usage clock - No Backend
   *   CLOCK_HIGHRES (4)  non-adjustable, high-resolution clock
*** 191,204 ****
          sev.sigev_notify = ltos_sigev[lev.lx_sigev_notify];
          sev.sigev_signo = ltos_signo[lev.lx_sigev_signo];
          sev.sigev_value = lev.lx_sigev_value;
  
          /*
!          * The sigevent sigev_notify_function and sigev_notify_attributes
!          * members are not used by timer_create, so no conversion is needed.
           */
  
          return ((timer_create(ltos_timer[clock], &sev, tid) < 0) ? -errno : 0);
  }
  
  long
  lx_timer_settime(timer_t tid, int flags, struct itimerspec *new_val,
--- 212,271 ----
          sev.sigev_notify = ltos_sigev[lev.lx_sigev_notify];
          sev.sigev_signo = ltos_signo[lev.lx_sigev_signo];
          sev.sigev_value = lev.lx_sigev_value;
  
          /*
!          * Assume all Linux libc implementations map SIGEV_THREAD to
!          * SIGEV_THREAD_ID and ignore passed-in attributes.
           */
+         sev.sigev_notify_attributes = NULL;
  
+         if (lev.lx_sigev_notify == LX_SIGEV_THREAD_ID) {
+                 pid_t caller_pid = getpid();
+                 pid_t target_pid;
+                 int rval;
+ 
+                 if ((rval = lx_lpid_to_spair(lev.lx_sigev_un.lx_tid,
+                             &target_pid, NULL)) != 0) {
+ 
+                         /*
+                          * Attempt to stick to the defined ERRORS in
+                          * timer_create(2).
+                          */
+                         if (rval == -ESRCH)
+                                 return (-EINVAL);
+ 
+                         return (rval);
+                 }
+ 
+                 /*
+                  * The caller of SIGEV_THREAD_ID must be in the same
+                  * process as the target thread.
+                  */
+                 if (caller_pid != target_pid)
+                         return (-EINVAL);
+ 
+                 /*
+                  * Pass the original lx sigevent_t to the native
+                  * notify function so that it may pass it to the lx
+                  * helper thread. It is the responsibility of
+                  * lx_sigev_thread_id() to free lev_copy after the
+                  * information is relayed to lx.
+                  */
+                 lx_sigevent_t *lev_copy = malloc(sizeof (lx_sigevent_t));
+                 if (lev_copy == NULL)
+                         return (-ENOMEM);
+ 
+                 if (uucopy(&lev, lev_copy, sizeof (lx_sigevent_t)) < 0) {
+                         free(lev_copy);
+                         return (-EFAULT);
+                 }
+ 
+                 sev.sigev_notify_function = lx_sigev_thread_id;
+                 sev.sigev_value.sival_ptr = lev_copy;
+         }
+ 
          return ((timer_create(ltos_timer[clock], &sev, tid) < 0) ? -errno : 0);
  }
  
  long
  lx_timer_settime(timer_t tid, int flags, struct itimerspec *new_val,