70 lines
2.5 KiB
C
70 lines
2.5 KiB
C
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/****************************************************************************
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* libs/libc/misc/lib_ftok.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 <sys/types.h>
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#include <sys/stat.h>
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#include <sys/ipc.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: ftok
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*
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* Description:
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* Convert a pathname and a project identifier to a System V IPC key.
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* The ftok() function uses the identity of the file named by the given
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* pathname (which must refer to an existing, accessible file) and the
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* least significant 8 bits of proj_id (which must be nonzero) to
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* generate a key_t type System V IPC key, suitable for use with
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* msgget(2), semget(2), or shmget(2).
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*
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* Input Parameters:
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* pathname - identity of the file name
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* proj_id - The value that uniquely project identifies.
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*
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* Returned Value:
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* On success, the generated key_t value is returned.
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* On failure -1 is returned, with errno indicating the error as for the
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* stat(2) system call.
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*
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****************************************************************************/
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key_t ftok(FAR const char *pathname, int proj_id)
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{
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struct stat st;
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if (stat(pathname, &st) < 0)
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{
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return (key_t)-1;
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}
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return ((key_t)proj_id << 24 |
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(key_t)(st.st_dev & 0xff) << 16 |
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(key_t)(st.st_ino & 0xffff));
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}
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