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76 lines
3.4 KiB
C
76 lines
3.4 KiB
C
/******************************************************************************
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* *
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* License Agreement *
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* *
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* Copyright (c) 2004 Altera Corporation, San Jose, California, USA. *
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* All rights reserved. *
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* *
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* Permission is hereby granted, free of charge, to any person obtaining a *
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* copy of this software and associated documentation files (the "Software"), *
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* to deal in the Software without restriction, including without limitation *
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* the rights to use, copy, modify, merge, publish, distribute, sublicense, *
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* and/or sell copies of the Software, and to permit persons to whom the *
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* Software is furnished to do so, subject to the following conditions: *
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* *
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* The above copyright notice and this permission notice shall be included in *
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* all copies or substantial portions of the Software. *
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* *
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR *
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE *
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER *
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING *
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER *
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* DEALINGS IN THE SOFTWARE. *
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* *
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* This agreement shall be governed in all respects by the laws of the State *
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* of California and by the laws of the United States of America. *
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* *
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* Altera does not recommend, suggest or require that this reference design *
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* file be used in conjunction or combination with any other product. *
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******************************************************************************/
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#include <errno.h>
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#include "priv/alt_file.h"
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/*
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* alt_fd_lock() is called as a consequence of an ioctl call to gain exclusive
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* access to a device, i.e.:
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*
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* ioctl (fd, TIOCEXCL, NULL);
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*
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* If there are no other open file descriptors which reference the same
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* device, then alt_fd_lock() will grant the lock. Further calls to open()
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* for this device will fail until the lock is released.
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*
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* This is done by calling close() for this file descriptor, or by calling:
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*
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* ioctl (fd, TIOCNXCL, NULL);
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*
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* The return value is zero for success, or negative in the case of failure.
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*/
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int alt_fd_lock (alt_fd* fd)
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{
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int i;
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int rc = 0;
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ALT_SEM_PEND(alt_fd_list_lock, 0);
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for (i = 0; i < alt_max_fd; i++)
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{
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if ((&alt_fd_list[i] != fd) && (alt_fd_list[i].dev == fd->dev))
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{
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rc = -EACCES;
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goto alt_fd_lock_exit;
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}
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}
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fd->fd_flags |= ALT_FD_EXCL;
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alt_fd_lock_exit:
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ALT_SEM_POST(alt_fd_list_lock);
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return rc;
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}
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