NuttX RTOS

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 273 insertions, 0 deletions

diff --git a/nuttx/sched/sig_action.c b/nuttx/sched/sig_action.c
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+/************************************************************
+ * sig_action.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <sys/types.h>
+#include <signal.h>
+#include <queue.h>
+#include <sched.h>
+#include "os_internal.h"
+#include "sig_internal.h"
+
+/************************************************************
+ * Definitions
+ ************************************************************/
+
+/************************************************************
+ * Private Type Declarations
+ ************************************************************/
+
+/************************************************************
+ * Global Variables
+ ************************************************************/
+
+/************************************************************
+ * Private Variables
+ ************************************************************/
+
+/************************************************************
+ * Private Functions
+ ************************************************************/
+
+/************************************************************
+ * Function: sig_allocateaction
+ *
+ * Description:
+ *   Allocate a new element for a sigaction queue
+ *
+ ************************************************************/
+
+static sigactq_t *sig_allocateaction(void)
+{
+  sigactq_t *sigact;
+
+  /* Try to get the signal action structure from the free list */
+
+  sigact = (sigactq_t*)sq_remfirst(&g_sigfreeaction);
+
+  /* Check if we got one. */
+
+  if (!sigact)
+    {
+      /* Add another block of signal actions to the list */
+
+      sig_allocateactionblock();
+
+      /* And try again */
+
+      sigact = (sigactq_t*)sq_remfirst(&g_sigfreeaction);
+      if (!sigact)
+        {
+          PANIC(OSERR_OUTOFMEMORY);
+        }
+  }
+
+  return sigact;
+}
+
+/************************************************************
+ * Public Functions
+ ************************************************************/
+
+/************************************************************
+ * Function: sigaction
+ *
+ * Description:
+ *   This function allows the calling process to examine
+ *   and/or specify the action to be associated with a
+ *   specific signal.
+ *
+ *   The structure sigaction, used to describe an action to
+ *   be taken, is defined to include the following members:
+ *
+ *   - sa_u.sa_handler:  Pointer to a signal-catching
+ *       function
+ *   - sa_u.sa_sigaction:  Alternative form of the
+ *       signal-catching function
+ *   - sa_mask: An additional set of signals to be blocked
+ *       during execution of a signal catching function
+ *   - sa_flags.  Special flags to affect the behavior of a
+ *       signal.
+ *
+ *   If the argument 'act' is not NULL, it points to a
+ *   structure specifying the action to be associated with
+ *   the specified signal.  If the argument 'oact' is not
+ *   NULL, the action previously associated with the signal
+ *   is stored in the location pointed to by the argument
+ *   'oact.'
+ *
+ *   When a signal is caught by a signal-catching function
+ *   installed by sigaction() function, a new signal mask is 
+ *   calculated and installed for the duration of the
+ *   signal-catching function.  This mask is formed by taking
+ *   the union of the current signal mask and the value of the
+ *   sa_mask for the signal being delivered and then including
+ *   the signal being delivered.  If and when the user's signal
+ *   handler returns, the original signal mask is restored.
+ *
+ *   Once an action is installed for a specific signal, it
+ *   remains installed until another action is explicitly
+ *   requested by another call to sigaction().
+ *
+ * Parameters:
+ *   sig - Signal of interest
+ *   act - Location of new handler
+ *   oact - Location to store only handler
+ *
+ * Return Value:
+ *   0 (OK), or -1 (ERROR) if the signal number is invalid.
+ *   (errno is not set)
+ *
+ * Assumptions:
+ *
+ * POSIX Compatibility:
+ * - Special values of sa_handler in the struct sigaction
+ *   act input not handled (SIG_DFL, SIG_IGN).
+ * - All sa_flags in struct sigaction of act input are
+ *   ignored (all treated like SA_SIGINFO).
+ *
+ ************************************************************/
+
+int sigaction(int signo, const struct sigaction *act,
+              struct sigaction *oact)
+{
+  _TCB      *rtcb = (_TCB*)g_readytorun.head;
+  sigactq_t *sigact;
+  int        ret = ERROR;  /* Assume failure */
+
+  /* Since sigactions can only be installed from the running
+   * thread of execution, no special precautions should be
+   * necessary. */
+
+  /* Verify the signal */
+
+  if (GOOD_SIGNO(signo))
+    {
+      ret = OK;  /* Assume success */
+
+      /* Find the signal in the sigactionq */
+
+      sigact = sig_findaction(rtcb, signo);
+
+      /* Return the old sigaction value if so requested */
+
+      if (oact)
+        {
+          if (sigact)
+            {
+              *oact = sigact->act;
+            }
+          else
+            {
+              /* There isn't an old value */
+
+              oact->sa_u._sa_handler = NULL;
+              oact->sa_mask = NULL_SIGNAL_SET;
+              oact->sa_flags = 0;
+            }
+        }
+
+      /* If no sigaction was found, but one is needed, then
+       * allocate one.
+       */
+
+      if (!sigact && act && act->sa_u._sa_handler)
+        {
+          sigact = sig_allocateaction();
+
+          /* An error has occurred if we could not allocate the sigaction */
+
+          if (!sigact)
+            {
+              ret = ERROR;
+            }
+          else
+            {
+              /* Put the signal number in the queue entry */
+
+              sigact->signo = (ubyte)signo;
+
+              /* Add the new sigaction to sigactionq */
+
+              sq_addlast((sq_entry_t*)sigact, &rtcb->sigactionq);
+            }
+        }
+
+      /* Set the new sigaction if so requested */
+
+      if ((sigact) && (act))
+        {
+          /* Check if it is a request to install a new handler */
+
+          if (act->sa_u._sa_handler)
+            {
+              sigact->act = *act;
+            }
+
+          /* No.. It is a request to remove the old handler */
+
+          else
+            {
+              /* Remove the old sigaction from sigactionq */
+
+              sq_rem((sq_entry_t*)sigact, &rtcb->sigactionq);
+
+              /* And deallocate it */
+
+              sig_releaseaction(sigact);
+            }
+        }
+    }
+
+  return ret;
+}
+
+/************************************************************
+ * Function:  sig_releaseaction
+ *
+ * Description:
+ *   Deallocate a sigaction Q entry
+ *
+ ************************************************************/
+
+void sig_releaseaction(sigactq_t *sigact)
+{
+  /* Just put it back on the free list */
+
+  sq_addlast((sq_entry_t*)sigact, &g_sigfreeaction);
+}