fopen android,fopen.c - Android社区 - https://www.androidos.net.cn/-优快云博客

/*-

* This code is derived from software contributed to Berkeley by

* Chris Torek.

* 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 of the University 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 REGENTS 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 REGENTS 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.

#if defined(LIBC_SCCS) && !defined(lint)

static char sccsid[] = "@(#)fopen.c8.1 (Berkeley) 6/4/93";

#endif /* LIBC_SCCS and not lint */

#include __FBSDID("$FreeBSD$");

#include "namespace.h"

#include #include #include #include #include #include #include #include "un-namespace.h"

#include "local.h"

FILE *

fopen(const char * __restrict file, const char * __restrict mode)

{

FILE *fp;

int f;

int flags, oflags;

if ((flags = __sflags(mode, &oflags)) == 0)

return (NULL);

if ((fp = __sfp()) == NULL)

return (NULL);

if ((f = _open(file, oflags, DEFFILEMODE)) < 0) {

fp->_flags = 0;/* release */

return (NULL);

}

* File descriptors are a full int, but _file is only a short.

* If we get a valid file descriptor that is greater than

* SHRT_MAX, then the fd will get sign-extended into an

* invalid file descriptor. Handle this case by failing the

* open.

if (f > SHRT_MAX) {

fp->_flags = 0;/* release */

_close(f);

errno = EMFILE;

return (NULL);

}

fp->_file = f;

fp->_flags = flags;

fp->_cookie = fp;

fp->_read = __sread;

fp->_write = __swrite;

fp->_seek = __sseek;

fp->_close = __sclose;

* When opening in append mode, even though we use O_APPEND,

* we need to seek to the end so that ftell() gets the right

* answer. If the user then alters the seek pointer, or

* the file extends, this will fail, but there is not much

* we can do about this. (We could set __SAPP and check in

* fseek and ftell.)

if (oflags & O_APPEND)

(void)_sseek(fp, (fpos_t)0, SEEK_END);

return (fp);

}

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