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109 lines
3.2 KiB
C
109 lines
3.2 KiB
C
/* Copyright (C) 1991, 1992, 1993 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#include <ansidecl.h>
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#include <errno.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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/* Defined in fopen.c. */
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extern int EXFUN(__getmode, (CONST char *mode, __io_mode *mptr));
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/* Open a new stream that will read and/or write from the buffer in
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S, which is of LEN bytes. If the mode indicates appending, the
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buffer pointer is set to point to the first '\0' in the buffer.
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If S is NULL, the buffer is allocated by malloc and will be freed
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when the stream is closed. The only purpose of this is to write
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things and then read what's been written. If LEN is zero, writes will
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always return errors and reads will always return end-of-file.
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The stream is set up such that seeks and tells will always fail and
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once the buffer is full of written characters or empty of characters
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to read, attempted writes always return an output error and attempted
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reads always return end-of-file. */
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FILE *
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DEFUN(fmemopen, (s, len, mode),
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PTR s AND size_t len AND CONST char *mode)
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{
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__io_mode m;
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register FILE *stream;
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if (!__getmode (mode, &m))
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return NULL;
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stream = __newstream ();
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if (stream == NULL)
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return NULL;
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stream->__mode = m;
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/* Input gets EOF. */
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stream->__room_funcs.__input = NULL;
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/* Output gets error. */
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stream->__room_funcs.__output = NULL;
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/* Do nothing for close. */
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stream->__io_funcs.__close = NULL;
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/* Can't seek outside the buffer. */
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stream->__io_funcs.__seek = NULL;
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/* There is no associated file descriptor to fetch. */
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stream->__io_funcs.__fileno = NULL;
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stream->__seen = 1;
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stream->__userbuf = s != NULL && len > 0;
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if (s == NULL)
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{
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s = malloc (len);
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if (s == NULL)
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{
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int save = errno;
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(void) fclose (stream);
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errno = save;
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return NULL;
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}
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}
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stream->__buffer = (char *) s;
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stream->__bufsize = len;
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stream->__bufp = stream->__buffer;
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stream->__get_limit = (stream->__buffer +
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(stream->__mode.__read ? stream->__bufsize : 0));
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stream->__put_limit = (stream->__buffer +
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(stream->__mode.__write ? stream->__bufsize : 0));
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stream->__cookie = NULL;
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if (stream->__mode.__append)
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{
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char *p = memchr (stream->__bufp, '\0',
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stream->__get_limit - stream->__bufp);
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if (p == NULL)
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stream->__bufp = stream->__get_limit;
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else
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stream->__bufp = p;
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}
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else if (stream->__mode.__truncate)
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memset ((PTR) stream->__buffer, 0, len);
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return stream;
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}
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