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      1 /* $NetBSD: buf.h,v 1.1 2022/01/22 07:54:57 pho Exp $ */
      2 
      3 /*
      4  * Copyright (c) 2021 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. The name of the author may not be used to endorse or promote
     16  *    products derived from this software without specific prior written
     17  *    permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
     20  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     21  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
     23  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
     25  * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     27  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
     28  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     29  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 #if !defined(_FUSE_BUF_H_)
     32 #define _FUSE_BUF_H_
     33 
     34 #include <sys/types.h>
     35 
     36 /* Data buffer API, appeared on FUSE 2.9. */
     37 
     38 #if !defined(FUSE_H_)
     39 #  error Do not include this header directly. Include <fuse.h> instead.
     40 #endif
     41 
     42 #ifdef __cplusplus
     43 extern "C" {
     44 #endif
     45 
     46 enum fuse_buf_flags {
     47 	/* The buffer is actually an fd: .mem is invalid but .fd and
     48 	 * .pos have valid values. */
     49 	FUSE_BUF_IS_FD		= (1 << 1),
     50 	/* The fd is seekable. */
     51 	FUSE_BUF_FD_SEEK	= (1 << 2),
     52 	/* Keep reading from/writing to the fd until reaching EOF. */
     53 	FUSE_BUF_FD_RETRY	= (1 << 3),
     54 };
     55 enum fuse_buf_copy_flags {
     56 	/* These flags are always ignored because splice(2) is a
     57 	 * Linux-specific syscall and there are no alternatives on
     58 	 * NetBSD atm. */
     59 	FUSE_BUF_NO_SPLICE		= (1 << 1),
     60 	FUSE_BUF_FORCE_SPLICE		= (1 << 2),
     61 	FUSE_BUF_SPLICE_MOVE		= (1 << 3),
     62 	FUSE_BUF_SPLICE_NONBLOCK	= (1 << 4),
     63 };
     64 struct fuse_buf {
     65 	size_t			size;
     66 	enum fuse_buf_flags	flags;
     67 	void			*mem;
     68 	int			fd;
     69 	off_t			pos;
     70 };
     71 struct fuse_bufvec {
     72 	/* The number of buffers in the vector. */
     73 	size_t		count;
     74 	/* The index of the current buffer in the vector. */
     75 	size_t		idx;
     76 	/* The current offset in the current buffer. */
     77 	size_t		off;
     78 	/* The vector of buffers. */
     79 	struct fuse_buf	buf[1];
     80 };
     81 #define FUSE_BUFVEC_INIT(size_)				\
     82 	((struct fuse_bufvec) {				\
     83 		/* .count = */ 1,			\
     84 		/* .idx = */ 0,				\
     85 		/* .off = */ 0,				\
     86 		/* .buf = */ {				\
     87 			/* [0] = */ {			\
     88 				/* .size = */ (size_)	\
     89 				/* .flags = */ (enum fuse_buf_flags)0,	\
     90 				/* .mem = */ NULL,	\
     91 				/* .fd = */ -1,		\
     92 				/* .pos = */ 0,		\
     93 			}				\
     94 		}					\
     95 	})
     96 
     97 /* Get the total size of data in a buffer vector. */
     98 size_t fuse_buf_size(const struct fuse_bufvec *bufv);
     99 
    100 /* Copy data from one buffer vector to another, and return the number
    101  * of octets that have been copied. */
    102 ssize_t fuse_buf_copy(struct fuse_bufvec *dstv, struct fuse_bufvec *srcv,
    103 					  enum fuse_buf_copy_flags flags);
    104 
    105 #ifdef __cplusplus
    106 }
    107 #endif
    108 
    109 #endif
    110