making libscp a real library

some fixes in configuration options

1 files changed, 146 insertions, 0 deletions

diff --git a/sesman/libscp/libscp_lock.c b/sesman/libscp/libscp_lock.c
new file mode 100644
index 00000000..abc110d6
--- /dev/null
+++ b/sesman/libscp/libscp_lock.c
@@ -0,0 +1,146 @@
+/*
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+   xrdp: A Remote Desktop Protocol server.
+   Copyright (C) Jay Sorg 2005-2007
+
+   session manager
+   linux only
+
+*/
+
+#include "libscp_lock.h"
+
+#include <semaphore.h>
+#include <pthread.h>
+
+pthread_mutex_t lock_fork;            /* this lock protects the counters */
+pthread_mutexattr_t lock_fork_attr;   /* mutex attributes */
+sem_t lock_fork_req;                  /* semaphore on which the process that are going to fork suspend on */
+sem_t lock_fork_wait;                 /* semaphore on which the suspended process wait on */
+int lock_fork_forkers_count;          /* threads that want to fork */
+int lock_fork_blockers_count;         /* threads thar are blocking fork */
+int lock_fork_waiting_count;          /* threads suspended until the fork finishes */
+
+void DEFAULT_CC
+scp_lock_init(void)
+{
+  /* initializing fork lock */
+  pthread_mutexattr_init(&lock_fork_attr);
+  pthread_mutex_init(&lock_fork, &lock_fork_attr);
+  sem_init(&lock_fork_req, 0, 0);
+  sem_init(&lock_fork_wait, 0, 0);
+
+  /* here we don't use locking because lock_init() should be called BEFORE */
+  /* any thread is created                                                 */
+  lock_fork_blockers_count=0;
+  lock_fork_waiting_count=0;
+  lock_fork_forkers_count=0;
+}
+
+/******************************************************************************/
+void DEFAULT_CC
+scp_lock_fork_request(void)
+{
+  /* lock mutex */
+  pthread_mutex_lock(&lock_fork);
+  if (lock_fork_blockers_count == 0)
+  {
+    /* if noone is blocking fork(), then we're allowed to fork */
+    sem_post(&lock_fork_req);
+  }
+  lock_fork_forkers_count++;
+  pthread_mutex_unlock(&lock_fork);
+
+  /* we wait to be allowed to fork() */
+  sem_wait(&lock_fork_req);
+}
+
+/******************************************************************************/
+void DEFAULT_CC
+scp_lock_fork_release(void)
+{
+  pthread_mutex_lock(&lock_fork);
+  lock_fork_forkers_count--;
+
+  /* if there's someone else that want to fork, we let him fork() */
+  if (lock_fork_forkers_count > 0)
+  {
+    sem_post(&lock_fork_req);
+  }
+
+  for (;lock_fork_waiting_count > 0; lock_fork_waiting_count--)
+  {
+    /* waking up the other processes */
+    sem_post(&lock_fork_wait);
+  }
+  pthread_mutex_unlock(&lock_fork);
+}
+
+/******************************************************************************/
+void DEFAULT_CC
+scp_lock_fork_critical_section_end(int blocking)
+{
+  //LOG_DBG("lock_fork_critical_secection_end()",0);
+  /* lock mutex */
+  pthread_mutex_lock(&lock_fork);
+
+  if (blocking == LIBSCP_LOCK_FORK_BLOCKER)
+  {
+    lock_fork_blockers_count--;
+  }
+
+  /* if there's someone who wants to fork and we're the last blocking */
+  /* then we let him go */
+  if ((lock_fork_blockers_count == 0) && (lock_fork_forkers_count>0))
+  {
+    sem_post(&lock_fork_req);
+  }
+  pthread_mutex_unlock(&lock_fork);
+}
+
+/******************************************************************************/
+int DEFAULT_CC
+scp_lock_fork_critical_section_start(void)
+{
+  //LOG_DBG("lock_fork_critical_secection_start()",0);
+  do
+  {
+    pthread_mutex_lock(&lock_fork);
+
+    /* someone requested to fork */
+    if (lock_fork_forkers_count > 0)
+    {
+      lock_fork_waiting_count++;
+      pthread_mutex_unlock(&lock_fork);
+
+      /* we wait until the fork finishes */
+      sem_wait(&lock_fork_wait);
+
+    }
+    else
+    {
+      /* no fork, so we can go on... */
+      lock_fork_blockers_count++;
+      pthread_mutex_unlock(&lock_fork);
+
+      return LIBSCP_LOCK_FORK_BLOCKER;
+    }
+  } while (1);
+
+  /* we'll never get here */
+  return LIBSCP_LOCK_FORK_WAITING;
+}
+