diff options
Diffstat (limited to 'nuttx/sched/errno_getptr.c')
-rw-r--r-- | nuttx/sched/errno_getptr.c | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/nuttx/sched/errno_getptr.c b/nuttx/sched/errno_getptr.c new file mode 100644 index 000000000..0b27768da --- /dev/null +++ b/nuttx/sched/errno_getptr.c @@ -0,0 +1,117 @@ +/**************************************************************************** + * sched/errno_getptr.c + * + * Copyright (C) 2007, 2008, 2011 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <gnutt@nuttx.org> + * + * 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 NuttX 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 <nuttx/config.h> +#include <sched.h> +#include <errno.h> +#include <nuttx/arch.h> +#include "os_internal.h" + +/**************************************************************************** + * Pre-processor Definitions + ****************************************************************************/ + +#undef get_errno_ptr +#undef errno + +/**************************************************************************** + * Private Data + ****************************************************************************/ + +static int g_irqerrno; + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: get_errno_ptr + * + * Description: + * Return a pointer to the thread specific errno. + * + * Parameters: + * None + * + * Return Value: + * A pointer to the per-thread errno variable. + * + * Assumptions: + * + ****************************************************************************/ + +FAR int *get_errno_ptr(void) +{ + /* Check if this function was called from an interrupt handler. In that + * case, we have to do things a little differently to prevent the interrupt + * handler from modifying the tasks errno value. + */ + + if (!up_interrupt_context()) + { + /* We were called from the normal tasking context. Verify that the + * task at the head of the ready-to-run list is actually running. It + * may not be running during very brief times during context switching + * logic (see, for example, task_deletecurrent.c). + */ + + FAR _TCB *rtcb = (FAR _TCB*)g_readytorun.head; + if (rtcb->task_state == TSTATE_TASK_RUNNING) + { + /* Yes.. the task is running normally. Return a reference to the + * thread-private errno in the TCB of the running task. + */ + + return &rtcb->pterrno; + } + } + + /* We were called either from (1) an interrupt handler or (2) from normally + * code but in an unhealthy state. In either event, do not permit access to + * the errno in the TCB of the task at the head of the ready-to-run list. + * Instead, use a separate errno just for interrupt handlers. Of course, this + * would have to change if we ever wanted to support nested interrupts or if + * we really cared about the stability of the errno during those "unhealthy + * states." + */ + + return &g_irqerrno; +} + + |