/* crypto/bio/bss_bio.c  -*- Mode: C; c-file-style: "eay" -*- */

 /* ====================================================================

  * Copyright (c) 1998-2003 The OpenSSL Project.  All rights reserved.

  *

  * 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. All advertising materials mentioning features or use of this

  *    software must display the following acknowledgment:

  *    "This product includes software developed by the OpenSSL Project

  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"

  *

  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to

  *    endorse or promote products derived from this software without

  *    prior written permission. For written permission, please contact

  *    openssl-core@openssl.org.

  *

  * 5. Products derived from this software may not be called "OpenSSL"

  *    nor may "OpenSSL" appear in their names without prior written

  *    permission of the OpenSSL Project.

  *

  * 6. Redistributions of any form whatsoever must retain the following

  *    acknowledgment:

  *    "This product includes software developed by the OpenSSL Project

  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"

  *

  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY

  * EXPRESSED 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 OpenSSL PROJECT OR

  * ITS 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.

  * ====================================================================

  *

  * This product includes cryptographic software written by Eric Young

  * (eay@cryptsoft.com).  This product includes software written by Tim

  * Hudson (tjh@cryptsoft.com).

  *

  */

 /*

  © Portions copyright (c) 2006 Nokia Corporation.  All rights reserved.

  */

 /* Special method for a BIO where the other endpoint is also a BIO

  * of this kind, handled by the same thread (i.e. the "peer" is actually

  * ourselves, wearing a different hat).

  * Such "BIO pairs" are mainly for using the SSL library with I/O interfaces

  * for which no specific BIO method is available.

  * See ssl/ssltest.c for some hints on how this can be used. */

 /* BIO_DEBUG implies BIO_PAIR_DEBUG */

 #ifdef BIO_DEBUG

 # ifndef BIO_PAIR_DEBUG

 #  define BIO_PAIR_DEBUG

 # endif

 #endif

 /* disable assert() unless BIO_PAIR_DEBUG has been defined */

 #ifndef BIO_PAIR_DEBUG

 # ifndef NDEBUG

 #  define NDEBUG

 # endif

 #endif

 #include <assert.h>

 #include <limits.h>

 #include <stdlib.h>

 #include <string.h>

 #include <openssl/bio.h>

 #include <openssl/err.h>

 #include <openssl/crypto.h>

 #include "e_os.h"

 #if (defined(SYMBIAN) && (defined(__WINSCW__) || defined(__WINS__)))

 #include "libcrypto_wsd_macros.h"

 #include "libcrypto_wsd.h"

 #endif

 /* VxWorks defines SSIZE_MAX with an empty value causing compile errors */

 #if defined(OPENSSL_SYS_VXWORKS)

 # undef SSIZE_MAX

 #endif

 #ifndef SSIZE_MAX

 # define SSIZE_MAX INT_MAX

 #endif

 static int bio_new(BIO *bio);

 static int bio_free(BIO *bio);

 static int bio_read(BIO *bio, char *buf, int size);

 static int bio_write(BIO *bio, const char *buf, int num);

 static long bio_ctrl(BIO *bio, int cmd, long num, void *ptr);

 static int bio_puts(BIO *bio, const char *str);

 static int bio_make_pair(BIO *bio1, BIO *bio2);

 static void bio_destroy_pair(BIO *bio);

 #ifndef EMULATOR

 static BIO_METHOD methods_biop =

 {

 	BIO_TYPE_BIO,

 	"BIO pair",

 	bio_write,

 	bio_read,

 	bio_puts,

 	NULL /* no bio_gets */,

 	bio_ctrl,

 	bio_new,

 	bio_free,

 	NULL /* no bio_callback_ctrl */

 };

 #else

 GET_STATIC_VAR_FROM_TLS(methods_biop,bss_bio,BIO_METHOD)

 #define methods_biop (*GET_WSD_VAR_NAME(methods_biop,bss_bio,s)())

 const BIO_METHOD temp_s_methods_biop =

 {

 	BIO_TYPE_BIO,

 	"BIO pair",

 	bio_write,

 	bio_read,

 	bio_puts,

 	NULL /* no bio_gets */,

 	bio_ctrl,

 	bio_new,

 	bio_free,

 	NULL /* no bio_callback_ctrl */

 };

 #endif	

 EXPORT_C BIO_METHOD *BIO_s_bio(void)

 	{

 	return &methods_biop;

 	}

 struct bio_bio_st

 {

 	BIO *peer;     /* NULL if buf == NULL.

 	                * If peer != NULL, then peer->ptr is also a bio_bio_st,

 	                * and its "peer" member points back to us.

 	                * peer != NULL iff init != 0 in the BIO. */

 	/* This is for what we write (i.e. reading uses peer's struct): */

 	int closed;     /* valid iff peer != NULL */

 	size_t len;     /* valid iff buf != NULL; 0 if peer == NULL */

 	size_t offset;  /* valid iff buf != NULL; 0 if len == 0 */

 	size_t size;

 	char *buf;      /* "size" elements (if != NULL) */

 	size_t request; /* valid iff peer != NULL; 0 if len != 0,

 	                 * otherwise set by peer to number of bytes

 	                 * it (unsuccessfully) tried to read,

 	                 * never more than buffer space (size-len) warrants. */

 };

 static int bio_new(BIO *bio)

 	{

 	struct bio_bio_st *b;

 	b = OPENSSL_malloc(sizeof *b);

 	if (b == NULL)

 		return 0;

 	b->peer = NULL;

 	b->size = 17*1024; /* enough for one TLS record (just a default) */

 	b->buf = NULL;

 	bio->ptr = b;

 	return 1;

 	}

 static int bio_free(BIO *bio)

 	{

 	struct bio_bio_st *b;

 	if (bio == NULL)

 		return 0;

 	b = bio->ptr;

 	assert(b != NULL);

 	if (b->peer)

 		bio_destroy_pair(bio);

 	if (b->buf != NULL)

 		{

 		OPENSSL_free(b->buf);

 		}

 	OPENSSL_free(b);

 	return 1;

 	}

 static int bio_read(BIO *bio, char *buf, int size_)

 	{

 	size_t size = size_;

 	size_t rest;

 	struct bio_bio_st *b, *peer_b;

 	BIO_clear_retry_flags(bio);

 	if (!bio->init)

 		return 0;

 	b = bio->ptr;

 	assert(b != NULL);

 	assert(b->peer != NULL);

 	peer_b = b->peer->ptr;

 	assert(peer_b != NULL);

 	assert(peer_b->buf != NULL);

 	peer_b->request = 0; /* will be set in "retry_read" situation */

 	if (buf == NULL || size == 0)

 		return 0;

 	if (peer_b->len == 0)

 		{

 		if (peer_b->closed)

 			return 0; /* writer has closed, and no data is left */

 		else

 			{

 			BIO_set_retry_read(bio); /* buffer is empty */

 			if (size <= peer_b->size)

 				peer_b->request = size;

 			else

 				/* don't ask for more than the peer can

 				 * deliver in one write */

 				peer_b->request = peer_b->size;

 			return -1;

 			}

 		}

 	/* we can read */

 	if (peer_b->len < size)

 		size = peer_b->len;

 	/* now read "size" bytes */

 	rest = size;

 	assert(rest > 0);

 	do /* one or two iterations */

 		{

 		size_t chunk;

 		assert(rest <= peer_b->len);

 		if (peer_b->offset + rest <= peer_b->size)

 			chunk = rest;

 		else

 			/* wrap around ring buffer */

 			chunk = peer_b->size - peer_b->offset;

 		assert(peer_b->offset + chunk <= peer_b->size);

 		memcpy(buf, peer_b->buf + peer_b->offset, chunk);

 		peer_b->len -= chunk;

 		if (peer_b->len)

 			{

 			peer_b->offset += chunk;

 			assert(peer_b->offset <= peer_b->size);

 			if (peer_b->offset == peer_b->size)

 				peer_b->offset = 0;

 			buf += chunk;

 			}

 		else

 			{

 			/* buffer now empty, no need to advance "buf" */

 			assert(chunk == rest);

 			peer_b->offset = 0;

 			}

 		rest -= chunk;

 		}

 	while (rest);

 	return size;

 	}

 /* non-copying interface: provide pointer to available data in buffer

  *    bio_nread0:  return number of available bytes

  *    bio_nread:   also advance index

  * (example usage:  bio_nread0(), read from buffer, bio_nread()

  *  or just         bio_nread(), read from buffer)

  */

 /* WARNING: The non-copying interface is largely untested as of yet

  * and may contain bugs. */

 static ssize_t bio_nread0(BIO *bio, char **buf)

 	{

 	struct bio_bio_st *b, *peer_b;

 	ssize_t num;

 	BIO_clear_retry_flags(bio);

 	if (!bio->init)

 		return 0;

 	b = bio->ptr;

 	assert(b != NULL);

 	assert(b->peer != NULL);

 	peer_b = b->peer->ptr;

 	assert(peer_b != NULL);

 	assert(peer_b->buf != NULL);

 	peer_b->request = 0;

 	if (peer_b->len == 0)

 		{

 		char dummy;

 		/* avoid code duplication -- nothing available for reading */

 		return bio_read(bio, &dummy, 1); /* returns 0 or -1 */

 		}

 	num = peer_b->len;

 	if (peer_b->size < peer_b->offset + num)

 		/* no ring buffer wrap-around for non-copying interface */

 		num = peer_b->size - peer_b->offset;

 	assert(num > 0);

 	if (buf != NULL)

 		*buf = peer_b->buf + peer_b->offset;

 	return num;

 	}

 static ssize_t bio_nread(BIO *bio, char **buf, size_t num_)

 	{

 	struct bio_bio_st *b, *peer_b;

 	ssize_t num, available;

 	if (num_ > SSIZE_MAX)

 		num = SSIZE_MAX;

 	else

 		num = (ssize_t)num_;

 	available = bio_nread0(bio, buf);

 	if (num > available)

 		num = available;

 	if (num <= 0)

 		return num;

 	b = bio->ptr;

 	peer_b = b->peer->ptr;

 	peer_b->len -= num;

 	if (peer_b->len) 

 		{

 		peer_b->offset += num;

 		assert(peer_b->offset <= peer_b->size);

 		if (peer_b->offset == peer_b->size)

 			peer_b->offset = 0;

 		}

 	else

 		peer_b->offset = 0;

 	return num;

 	}

 static int bio_write(BIO *bio, const char *buf, int num_)

 	{

 	size_t num = num_;

 	size_t rest;

 	struct bio_bio_st *b;

 	BIO_clear_retry_flags(bio);

 	if (!bio->init || buf == NULL || num == 0)

 		return 0;

 	b = bio->ptr;		

 	assert(b != NULL);

 	assert(b->peer != NULL);

 	assert(b->buf != NULL);

 	b->request = 0;

 	if (b->closed)

 		{

 		/* we already closed */

 		BIOerr(BIO_F_BIO_WRITE, BIO_R_BROKEN_PIPE);

 		return -1;

 		}

 	assert(b->len <= b->size);

 	if (b->len == b->size)

 		{

 		BIO_set_retry_write(bio); /* buffer is full */

 		return -1;

 		}

 	/* we can write */

 	if (num > b->size - b->len)

 		num = b->size - b->len;

 	/* now write "num" bytes */

 	rest = num;

 	assert(rest > 0);

 	do /* one or two iterations */

 		{

 		size_t write_offset;

 		size_t chunk;

 		assert(b->len + rest <= b->size);

 		write_offset = b->offset + b->len;

 		if (write_offset >= b->size)

 			write_offset -= b->size;

 		/* b->buf[write_offset] is the first byte we can write to. */

 		if (write_offset + rest <= b->size)

 			chunk = rest;

 		else

 			/* wrap around ring buffer */

 			chunk = b->size - write_offset;

 		memcpy(b->buf + write_offset, buf, chunk);

 		b->len += chunk;

 		assert(b->len <= b->size);

 		rest -= chunk;

 		buf += chunk;

 		}

 	while (rest);

 	return num;

 	}

 /* non-copying interface: provide pointer to region to write to

  *   bio_nwrite0:  check how much space is available

  *   bio_nwrite:   also increase length

  * (example usage:  bio_nwrite0(), write to buffer, bio_nwrite()

  *  or just         bio_nwrite(), write to buffer)

  */

 static ssize_t bio_nwrite0(BIO *bio, char **buf)

 	{

 	struct bio_bio_st *b;

 	size_t num;

 	size_t write_offset;

 	BIO_clear_retry_flags(bio);

 	if (!bio->init)

 		return 0;

 	b = bio->ptr;		

 	assert(b != NULL);

 	assert(b->peer != NULL);

 	assert(b->buf != NULL);

 	b->request = 0;

 	if (b->closed)

 		{

 		BIOerr(BIO_F_BIO_NWRITE0, BIO_R_BROKEN_PIPE);

 		return -1;

 		}

 	assert(b->len <= b->size);

 	if (b->len == b->size)

 		{

 		BIO_set_retry_write(bio);

 		return -1;

 		}

 	num = b->size - b->len;

 	write_offset = b->offset + b->len;

 	if (write_offset >= b->size)

 		write_offset -= b->size;

 	if (write_offset + num > b->size)

 		/* no ring buffer wrap-around for non-copying interface

 		 * (to fulfil the promise by BIO_ctrl_get_write_guarantee,

 		 * BIO_nwrite may have to be called twice) */

 		num = b->size - write_offset;

 	if (buf != NULL)

 		*buf = b->buf + write_offset;

 	assert(write_offset + num <= b->size);

 	return num;

 	}

 static ssize_t bio_nwrite(BIO *bio, char **buf, size_t num_)

 	{

 	struct bio_bio_st *b;

 	ssize_t num, space;

 	if (num_ > SSIZE_MAX)

 		num = SSIZE_MAX;

 	else

 		num = (ssize_t)num_;

 	space = bio_nwrite0(bio, buf);

 	if (num > space)

 		num = space;

 	if (num <= 0)

 		return num;

 	b = bio->ptr;

 	assert(b != NULL);

 	b->len += num;

 	assert(b->len <= b->size);

 	return num;

 	}

 static long bio_ctrl(BIO *bio, int cmd, long num, void *ptr)

 	{

 	long ret;

 	struct bio_bio_st *b = bio->ptr;

 	assert(b != NULL);

 	switch (cmd)

 		{

 	/* specific CTRL codes */

 	case BIO_C_SET_WRITE_BUF_SIZE:

 		if (b->peer)

 			{

 			BIOerr(BIO_F_BIO_CTRL, BIO_R_IN_USE);

 			ret = 0;

 			}

 		else if (num == 0)

 			{

 			BIOerr(BIO_F_BIO_CTRL, BIO_R_INVALID_ARGUMENT);

 			ret = 0;

 			}

 		else

 			{

 			size_t new_size = num;

 			if (b->size != new_size)

 				{

 				if (b->buf) 

 					{

 					OPENSSL_free(b->buf);

 					b->buf = NULL;

 					}

 				b->size = new_size;

 				}

 			ret = 1;

 			}

 		break;

 	case BIO_C_GET_WRITE_BUF_SIZE:

 		ret = (long) b->size;

 		break;

 	case BIO_C_MAKE_BIO_PAIR:

 		{

 		BIO *other_bio = ptr;

 		if (bio_make_pair(bio, other_bio))

 			ret = 1;

 		else

 			ret = 0;

 		}

 		break;

 	case BIO_C_DESTROY_BIO_PAIR:

 		/* Affects both BIOs in the pair -- call just once!

 		 * Or let BIO_free(bio1); BIO_free(bio2); do the job. */

 		bio_destroy_pair(bio);

 		ret = 1;

 		break;

 	case BIO_C_GET_WRITE_GUARANTEE:

 		/* How many bytes can the caller feed to the next write

 		 * without having to keep any? */

 		if (b->peer == NULL || b->closed)

 			ret = 0;

 		else

 			ret = (long) b->size - b->len;

 		break;

 	case BIO_C_GET_READ_REQUEST:

 		/* If the peer unsuccessfully tried to read, how many bytes

 		 * were requested?  (As with BIO_CTRL_PENDING, that number

 		 * can usually be treated as boolean.) */

 		ret = (long) b->request;

 		break;

 	case BIO_C_RESET_READ_REQUEST:

 		/* Reset request.  (Can be useful after read attempts

 		 * at the other side that are meant to be non-blocking,

 		 * e.g. when probing SSL_read to see if any data is

 		 * available.) */

 		b->request = 0;

 		ret = 1;

 		break;

 	case BIO_C_SHUTDOWN_WR:

 		/* similar to shutdown(..., SHUT_WR) */

 		b->closed = 1;

 		ret = 1;

 		break;

 	case BIO_C_NREAD0:

 		/* prepare for non-copying read */

 		ret = (long) bio_nread0(bio, ptr);

 		break;

 	case BIO_C_NREAD:

 		/* non-copying read */

 		ret = (long) bio_nread(bio, ptr, (size_t) num);

 		break;

 	case BIO_C_NWRITE0:

 		/* prepare for non-copying write */

 		ret = (long) bio_nwrite0(bio, ptr);

 		break;

 	case BIO_C_NWRITE:

 		/* non-copying write */

 		ret = (long) bio_nwrite(bio, ptr, (size_t) num);

 		break;

 	/* standard CTRL codes follow */

 	case BIO_CTRL_RESET:

 		if (b->buf != NULL)

 			{

 			b->len = 0;

 			b->offset = 0;

 			}

 		ret = 0;

 		break;		

 	case BIO_CTRL_GET_CLOSE:

 		ret = bio->shutdown;

 		break;

 	case BIO_CTRL_SET_CLOSE:

 		bio->shutdown = (int) num;

 		ret = 1;

 		break;

 	case BIO_CTRL_PENDING:

 		if (b->peer != NULL)

 			{

 			struct bio_bio_st *peer_b = b->peer->ptr;

 			ret = (long) peer_b->len;

 			}

 		else

 			ret = 0;

 		break;

 	case BIO_CTRL_WPENDING:

 		if (b->buf != NULL)

 			ret = (long) b->len;

 		else

 			ret = 0;

 		break;

 	case BIO_CTRL_DUP:

 		/* See BIO_dup_chain for circumstances we have to expect. */

 		{

 		BIO *other_bio = ptr;

 		struct bio_bio_st *other_b;

 		assert(other_bio != NULL);

 		other_b = other_bio->ptr;

 		assert(other_b != NULL);

 		assert(other_b->buf == NULL); /* other_bio is always fresh */

 		other_b->size = b->size;

 		}

 		ret = 1;

 		break;

 	case BIO_CTRL_FLUSH:

 		ret = 1;

 		break;

 	case BIO_CTRL_EOF:

 		{

 		BIO *other_bio = ptr;

 		if (other_bio)

 			{

 			struct bio_bio_st *other_b = other_bio->ptr;

 			assert(other_b != NULL);

 			ret = other_b->len == 0 && other_b->closed;

 			}

 		else

 			ret = 1;

 		}

 		break;

 	default:

 		ret = 0;

 		}

 	return ret;

 	}

 static int bio_puts(BIO *bio, const char *str)

 	{

 	return bio_write(bio, str, strlen(str));

 	}

 static int bio_make_pair(BIO *bio1, BIO *bio2)

 	{

 	struct bio_bio_st *b1, *b2;

 	assert(bio1 != NULL);

 	assert(bio2 != NULL);

 	b1 = bio1->ptr;

 	b2 = bio2->ptr;

 	if (b1->peer != NULL || b2->peer != NULL)

 		{

 		BIOerr(BIO_F_BIO_MAKE_PAIR, BIO_R_IN_USE);

 		return 0;

 		}

 	if (b1->buf == NULL)

 		{

 		b1->buf = OPENSSL_malloc(b1->size);

 		if (b1->buf == NULL)

 			{

 			BIOerr(BIO_F_BIO_MAKE_PAIR, ERR_R_MALLOC_FAILURE);

 			return 0;

 			}

 		b1->len = 0;

 		b1->offset = 0;

 		}

 	if (b2->buf == NULL)

 		{

 		b2->buf = OPENSSL_malloc(b2->size);

 		if (b2->buf == NULL)

 			{

 			BIOerr(BIO_F_BIO_MAKE_PAIR, ERR_R_MALLOC_FAILURE);

 			return 0;

 			}

 		b2->len = 0;

 		b2->offset = 0;

 		}

 	b1->peer = bio2;

 	b1->closed = 0;

 	b1->request = 0;

 	b2->peer = bio1;

 	b2->closed = 0;

 	b2->request = 0;

 	bio1->init = 1;

 	bio2->init = 1;

 	return 1;

 	}

 static void bio_destroy_pair(BIO *bio)

 	{

 	struct bio_bio_st *b = bio->ptr;

 	if (b != NULL)

 		{

 		BIO *peer_bio = b->peer;

 		if (peer_bio != NULL)

 			{

 			struct bio_bio_st *peer_b = peer_bio->ptr;

 			assert(peer_b != NULL);

 			assert(peer_b->peer == bio);

 			peer_b->peer = NULL;

 			peer_bio->init = 0;

 			assert(peer_b->buf != NULL);

 			peer_b->len = 0;

 			peer_b->offset = 0;

 			b->peer = NULL;

 			bio->init = 0;

 			assert(b->buf != NULL);

 			b->len = 0;

 			b->offset = 0;

 			}

 		}

 	}

 /* Exported convenience functions */

 EXPORT_C int BIO_new_bio_pair(BIO **bio1_p, size_t writebuf1,

 	BIO **bio2_p, size_t writebuf2)

 	 {

 	 BIO *bio1 = NULL, *bio2 = NULL;

 	 long r;

 	 int ret = 0;

 	 bio1 = BIO_new(BIO_s_bio());

 	 if (bio1 == NULL)

 		 goto err;

 	 bio2 = BIO_new(BIO_s_bio());

 	 if (bio2 == NULL)

 		 goto err;

 	 if (writebuf1)

 		 {

 		 r = BIO_set_write_buf_size(bio1, writebuf1);

 		 if (!r)

 			 goto err;

 		 }

 	 if (writebuf2)

 		 {

 		 r = BIO_set_write_buf_size(bio2, writebuf2);

 		 if (!r)

 			 goto err;

 		 }

 	 r = BIO_make_bio_pair(bio1, bio2);

 	 if (!r)

 		 goto err;

 	 ret = 1;

  err:

 	 if (ret == 0)

 		 {

 		 if (bio1)

 			 {

 			 BIO_free(bio1);

 			 bio1 = NULL;

 			 }

 		 if (bio2)

 			 {

 			 BIO_free(bio2);

 			 bio2 = NULL;

 			 }

 		 }

 	 *bio1_p = bio1;

 	 *bio2_p = bio2;

 	 return ret;

 	 }

 EXPORT_C size_t BIO_ctrl_get_write_guarantee(BIO *bio)

 	{

 	return BIO_ctrl(bio, BIO_C_GET_WRITE_GUARANTEE, 0, NULL);

 	}

 EXPORT_C size_t BIO_ctrl_get_read_request(BIO *bio)

 	{

 	return BIO_ctrl(bio, BIO_C_GET_READ_REQUEST, 0, NULL);

 	}

 EXPORT_C int BIO_ctrl_reset_read_request(BIO *bio)

 	{

 	return (BIO_ctrl(bio, BIO_C_RESET_READ_REQUEST, 0, NULL) != 0);

 	}

 /* BIO_nread0/nread/nwrite0/nwrite are available only for BIO pairs for now

  * (conceivably some other BIOs could allow non-copying reads and writes too.)

  */

 EXPORT_C int BIO_nread0(BIO *bio, char **buf)

 	{

 	long ret;

 	if (!bio->init)

 		{

 		BIOerr(BIO_F_BIO_NREAD0, BIO_R_UNINITIALIZED);

 		return -2;

 		}

 	ret = BIO_ctrl(bio, BIO_C_NREAD0, 0, buf);

 	if (ret > INT_MAX)

 		return INT_MAX;

 	else

 		return (int) ret;

 	}

 EXPORT_C int BIO_nread(BIO *bio, char **buf, int num)

 	{

 	int ret;

 	if (!bio->init)

 		{

 		BIOerr(BIO_F_BIO_NREAD, BIO_R_UNINITIALIZED);

 		return -2;

 		}

 	ret = (int) BIO_ctrl(bio, BIO_C_NREAD, num, buf);

 	if (ret > 0)

 		bio->num_read += ret;

 	return ret;

 	}

 EXPORT_C int BIO_nwrite0(BIO *bio, char **buf)

 	{

 	long ret;

 	if (!bio->init)

 		{

 		BIOerr(BIO_F_BIO_NWRITE0, BIO_R_UNINITIALIZED);

 		return -2;

 		}

 	ret = BIO_ctrl(bio, BIO_C_NWRITE0, 0, buf);

 	if (ret > INT_MAX)

 		return INT_MAX;

 	else

 		return (int) ret;

 	}

 EXPORT_C int BIO_nwrite(BIO *bio, char **buf, int num)

 	{

 	int ret;

 	if (!bio->init)

 		{

 		BIOerr(BIO_F_BIO_NWRITE, BIO_R_UNINITIALIZED);

 		return -2;

 		}

 	ret = BIO_ctrl(bio, BIO_C_NWRITE, num, buf);

 	if (ret > 0)

 		bio->num_read += ret;

 	return ret;

 	}