mirror of
https://github.com/autc04/Retro68.git
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279 lines
7.6 KiB
C
279 lines
7.6 KiB
C
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/* Copyright (C) 2007 Eric Blake
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* Permission to use, copy, modify, and distribute this software
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* is freely granted, provided that this notice is preserved.
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*/
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/*
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FUNCTION
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<<funopen>>, <<fropen>>, <<fwopen>>---open a stream with custom callbacks
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INDEX
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funopen
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INDEX
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fropen
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INDEX
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fwopen
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ANSI_SYNOPSIS
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#include <stdio.h>
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FILE *funopen(const void *<[cookie]>,
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int (*<[readfn]>) (void *cookie, char *buf, int n),
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int (*<[writefn]>) (void *cookie, const char *buf, int n),
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fpos_t (*<[seekfn]>) (void *cookie, fpos_t off, int whence),
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int (*<[closefn]>) (void *cookie));
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FILE *fropen(const void *<[cookie]>,
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int (*<[readfn]>) (void *cookie, char *buf, int n));
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FILE *fwopen(const void *<[cookie]>,
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int (*<[writefn]>) (void *cookie, const char *buf, int n));
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DESCRIPTION
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<<funopen>> creates a <<FILE>> stream where I/O is performed using
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custom callbacks. At least one of <[readfn]> and <[writefn]> must be
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provided, which determines whether the stream behaves with mode <"r">,
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<"w">, or <"r+">.
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<[readfn]> should return -1 on failure, or else the number of bytes
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read (0 on EOF). It is similar to <<read>>, except that <int> rather
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than <size_t> bounds a transaction size, and <[cookie]> will be passed
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as the first argument. A NULL <[readfn]> makes attempts to read the
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stream fail.
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<[writefn]> should return -1 on failure, or else the number of bytes
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written. It is similar to <<write>>, except that <int> rather than
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<size_t> bounds a transaction size, and <[cookie]> will be passed as
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the first argument. A NULL <[writefn]> makes attempts to write the
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stream fail.
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<[seekfn]> should return (fpos_t)-1 on failure, or else the current
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file position. It is similar to <<lseek>>, except that <[cookie]>
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will be passed as the first argument. A NULL <[seekfn]> makes the
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stream behave similarly to a pipe in relation to stdio functions that
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require positioning. This implementation assumes fpos_t and off_t are
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the same type.
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<[closefn]> should return -1 on failure, or 0 on success. It is
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similar to <<close>>, except that <[cookie]> will be passed as the
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first argument. A NULL <[closefn]> merely flushes all data then lets
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<<fclose>> succeed. A failed close will still invalidate the stream.
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Read and write I/O functions are allowed to change the underlying
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buffer on fully buffered or line buffered streams by calling
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<<setvbuf>>. They are also not required to completely fill or empty
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the buffer. They are not, however, allowed to change streams from
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unbuffered to buffered or to change the state of the line buffering
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flag. They must also be prepared to have read or write calls occur on
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buffers other than the one most recently specified.
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The functions <<fropen>> and <<fwopen>> are convenience macros around
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<<funopen>> that only use the specified callback.
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RETURNS
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The return value is an open FILE pointer on success. On error,
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<<NULL>> is returned, and <<errno>> will be set to EINVAL if a
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function pointer is missing, ENOMEM if the stream cannot be created,
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or EMFILE if too many streams are already open.
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PORTABILITY
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This function is a newlib extension, copying the prototype from BSD.
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It is not portable. See also the <<fopencookie>> interface from Linux.
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Supporting OS subroutines required: <<sbrk>>.
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*/
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#include <stdio.h>
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#include <errno.h>
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#include <sys/lock.h>
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#include "local.h"
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typedef int (*funread)(void *_cookie, char *_buf, int _n);
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typedef int (*funwrite)(void *_cookie, const char *_buf, int _n);
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#ifdef __LARGE64_FILES
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typedef _fpos64_t (*funseek)(void *_cookie, _fpos64_t _off, int _whence);
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#else
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typedef fpos_t (*funseek)(void *_cookie, fpos_t _off, int _whence);
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#endif
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typedef int (*funclose)(void *_cookie);
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typedef struct funcookie {
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void *cookie;
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funread readfn;
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funwrite writefn;
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funseek seekfn;
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funclose closefn;
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} funcookie;
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static _READ_WRITE_RETURN_TYPE
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_DEFUN(funreader, (ptr, cookie, buf, n),
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struct _reent *ptr _AND
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void *cookie _AND
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char *buf _AND
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int n)
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{
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int result;
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funcookie *c = (funcookie *) cookie;
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errno = 0;
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if ((result = c->readfn (c->cookie, buf, n)) < 0 && errno)
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ptr->_errno = errno;
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return result;
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}
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static _READ_WRITE_RETURN_TYPE
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_DEFUN(funwriter, (ptr, cookie, buf, n),
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struct _reent *ptr _AND
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void *cookie _AND
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const char *buf _AND
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int n)
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{
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int result;
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funcookie *c = (funcookie *) cookie;
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errno = 0;
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if ((result = c->writefn (c->cookie, buf, n)) < 0 && errno)
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ptr->_errno = errno;
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return result;
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}
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static _fpos_t
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_DEFUN(funseeker, (ptr, cookie, off, whence),
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struct _reent *ptr _AND
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void *cookie _AND
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_fpos_t off _AND
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int whence)
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{
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funcookie *c = (funcookie *) cookie;
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#ifndef __LARGE64_FILES
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fpos_t result;
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errno = 0;
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if ((result = c->seekfn (c->cookie, (fpos_t) off, whence)) < 0 && errno)
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ptr->_errno = errno;
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#else /* __LARGE64_FILES */
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_fpos64_t result;
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errno = 0;
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if ((result = c->seekfn (c->cookie, (_fpos64_t) off, whence)) < 0 && errno)
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ptr->_errno = errno;
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else if ((_fpos_t)result != result)
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{
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ptr->_errno = EOVERFLOW;
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result = -1;
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}
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#endif /* __LARGE64_FILES */
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return result;
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}
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#ifdef __LARGE64_FILES
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static _fpos64_t
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_DEFUN(funseeker64, (ptr, cookie, off, whence),
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struct _reent *ptr _AND
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void *cookie _AND
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_fpos64_t off _AND
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int whence)
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{
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_fpos64_t result;
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funcookie *c = (funcookie *) cookie;
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errno = 0;
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if ((result = c->seekfn (c->cookie, off, whence)) < 0 && errno)
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ptr->_errno = errno;
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return result;
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}
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#endif /* __LARGE64_FILES */
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static int
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_DEFUN(funcloser, (ptr, cookie),
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struct _reent *ptr _AND
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void *cookie)
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{
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int result = 0;
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funcookie *c = (funcookie *) cookie;
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if (c->closefn)
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{
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errno = 0;
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if ((result = c->closefn (c->cookie)) < 0 && errno)
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ptr->_errno = errno;
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}
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_free_r (ptr, c);
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return result;
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}
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FILE *
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_DEFUN(_funopen_r, (ptr, cookie, readfn, writefn, seekfn, closefn),
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struct _reent *ptr _AND
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const void *cookie _AND
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funread readfn _AND
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funwrite writefn _AND
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funseek seekfn _AND
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funclose closefn)
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{
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FILE *fp;
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funcookie *c;
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if (!readfn && !writefn)
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{
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ptr->_errno = EINVAL;
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return NULL;
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}
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if ((fp = __sfp (ptr)) == NULL)
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return NULL;
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if ((c = (funcookie *) _malloc_r (ptr, sizeof *c)) == NULL)
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{
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__sfp_lock_acquire ();
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fp->_flags = 0; /* release */
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#ifndef __SINGLE_THREAD__
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__lock_close_recursive (fp->_lock);
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#endif
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__sfp_lock_release ();
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return NULL;
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}
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_flockfile (fp);
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fp->_file = -1;
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c->cookie = (void *) cookie; /* cast away const */
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fp->_cookie = c;
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if (readfn)
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{
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c->readfn = readfn;
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fp->_read = funreader;
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if (writefn)
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{
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fp->_flags = __SRW;
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c->writefn = writefn;
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fp->_write = funwriter;
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}
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else
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{
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fp->_flags = __SRD;
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c->writefn = NULL;
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fp->_write = NULL;
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}
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}
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else
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{
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fp->_flags = __SWR;
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c->writefn = writefn;
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fp->_write = funwriter;
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c->readfn = NULL;
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fp->_read = NULL;
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}
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c->seekfn = seekfn;
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fp->_seek = seekfn ? funseeker : NULL;
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#ifdef __LARGE64_FILES
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fp->_seek64 = seekfn ? funseeker64 : NULL;
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fp->_flags |= __SL64;
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#endif
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c->closefn = closefn;
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fp->_close = funcloser;
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_funlockfile (fp);
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return fp;
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}
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#ifndef _REENT_ONLY
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FILE *
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_DEFUN(funopen, (cookie, readfn, writefn, seekfn, closefn),
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const void *cookie _AND
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funread readfn _AND
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funwrite writefn _AND
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funseek seekfn _AND
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funclose closefn)
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{
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return _funopen_r (_REENT, cookie, readfn, writefn, seekfn, closefn);
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}
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#endif /* !_REENT_ONLY */
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