ee4c25f34e
pointer comparison is unsigned, when returning -errno will be converted to a large positive number, can not enter the error handling branch, therefore, the error code is returned directly and the sem is returned through the parameters. Signed-off-by: zhanghongyu <zhanghongyu@xiaomi.com>
126 lines
4.0 KiB
C
126 lines
4.0 KiB
C
/****************************************************************************
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* libs/libc/semaphore/sem_open.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdarg.h>
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#include <string.h>
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#include <assert.h>
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#include <errno.h>
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#include <nuttx/semaphore.h>
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#ifdef CONFIG_FS_NAMED_SEMAPHORES
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: sem_open
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*
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* Description:
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* This function establishes a connection between named semaphores and a
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* task. Following a call to sem_open() with the semaphore name, the task
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* may reference the semaphore associated with name using the address
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* returned by this call. The semaphore may be used in subsequent calls
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* to sem_wait(), sem_trywait(), and sem_post(). The semaphore remains
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* usable until the semaphore is closed by a successful call to
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* sem_close().
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*
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* If a task makes multiple calls to sem_open() with the same name, then
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* the same semaphore address is returned (provided there have been no
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* calls to sem_unlink()).
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*
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* Input Parameters:
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* name - Semaphore name
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* oflags - Semaphore creation options. This may either or both of the
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* following bit settings.
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* oflags = 0: Connect to the semaphore only if it already exists.
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* oflags = O_CREAT: Connect to the semaphore if it exists, otherwise
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* create the semaphore.
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* oflags = O_CREAT|O_EXCL: Create a new semaphore
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* unless one of this name already exists.
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* Optional parameters. When the O_CREAT flag is specified, two optional
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* parameters are expected:
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* 1. mode_t mode, and
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* 2. unsigned int value. This initial value of the semaphore. Valid
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* initial values of the semaphore must be less than or equal to
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* SEM_VALUE_MAX.
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*
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* Returned Value:
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* A pointer to sem_t or SEM_FAILED if unsuccessful.
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*
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* Assumptions:
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*
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****************************************************************************/
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FAR sem_t *sem_open(FAR const char *name, int oflags, ...)
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{
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FAR sem_t *sem;
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va_list ap;
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mode_t mode;
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unsigned int value;
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int errcode;
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/* Make sure that a non-NULL name is supplied */
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DEBUGASSERT(name != NULL);
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if (name[0] == '/')
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{
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if (strlen(name) >= PATH_MAX)
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{
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set_errno(ENAMETOOLONG);
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return SEM_FAILED;
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}
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if (strlen(strrchr(name, '/') + 1) >= NAME_MAX)
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{
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set_errno(ENAMETOOLONG);
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return SEM_FAILED;
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}
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}
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/* Off-load the variadic list */
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va_start(ap, oflags);
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mode = va_arg(ap, mode_t);
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value = va_arg(ap, unsigned int);
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va_end(ap);
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/* Let nxsem_open() do the work */
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errcode = nxsem_open(&sem, name, oflags, mode, value);
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if (errcode < 0)
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{
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set_errno(-errcode);
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return SEM_FAILED;
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}
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return sem;
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}
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#endif /* CONFIG_FS_NAMED_SEMAPHORES */
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