/* $OpenBSD: fusebuf.h,v 1.16 2025/09/06 06:15:52 helg Exp $ */
/*
 * Copyright (c) 2013 Sylvestre Gallon
 * Copyright (c) 2013 Martin Pieuchot
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef _SYS_FUSEBUF_H_
#define _SYS_FUSEBUF_H_

/*
 * Maximum size of the read or write buffer sent from the kernel for VFS
 * syscalls: read, readdir, readlink, write.
 */
#define FUSEBUFMAXSIZE  (4096*1024)

/* header at beginning of each fusebuf: */
struct fb_hdr {
        SIMPLEQ_ENTRY(fusebuf)  fh_next;        /* next buffer in chain */
        size_t                  fh_len;         /* Amount of data */
        int                     fh_err;         /* errno to pass back */
        int                     fh_type;        /* type of data */
        ino_t                   fh_ino;         /* Inode of this fusebuf */
        uint64_t                fh_uuid;        /* Uuid to track the answer */
        pid_t                   fh_tid;         /* calling proc thread id */
        uid_t                   fh_uid;         /* calling proc uid */
        gid_t                   fh_gid;         /* calling proc gid */
        mode_t                  fh_umask;       /* calling proc umask */
};

/* header for fuse file operations (like read/write/mkdir): */
struct fb_io {
        uint64_t        fi_fd;          /* fd where the io is performed */
        ino_t           fi_ino;         /* ino for the io */
        off_t           fi_off;         /* offset for the io */
        size_t          fi_len;         /* Length of data */
        mode_t          fi_mode;        /* mode for fd */
        uint32_t        fi_flags;       /* flags on transfer */
        dev_t           fi_rdev;        /* dev for mknod */
};

/*
 * An operation is issued by the kernel through fuse(4) when the
 * userland file system needs to execute an action (mkdir(2),
 * link(2), etc).
 *
 * F_databuf can be superior to FUSELEN for fusefs_read, fusefs_writes and
 * fusefs_readdir. If it is the case the transfer will be split in N
 * fusebuf with a changing offset in FD_io.
 *
 * When the userland file system answers to this operation it uses
 * the same ID (fh_uuid).
 */
struct fusebuf {
        struct fb_hdr   fb_hdr;
        union {
                struct statvfs  FD_stat;        /* vfs statfs */
                struct stat     FD_attr;        /* for attr vnops */
                struct fb_io    FD_io;          /* for file io vnops */
        } FD;
        uint8_t *fb_dat;                        /* data's */
};

#define fb_next         fb_hdr.fh_next
#define fb_len          fb_hdr.fh_len
#define fb_err          fb_hdr.fh_err
#define fb_type         fb_hdr.fh_type
#define fb_ino          fb_hdr.fh_ino
#define fb_uuid         fb_hdr.fh_uuid
#define fb_tid          fb_hdr.fh_tid
#define fb_uid          fb_hdr.fh_uid
#define fb_gid          fb_hdr.fh_gid
#define fb_umask        fb_hdr.fh_umask

#define fb_stat         FD.FD_stat
#define fb_attr         FD.FD_attr
#define fb_io_fd        FD.FD_io.fi_fd
#define fb_io_ino       FD.FD_io.fi_ino
#define fb_io_off       FD.FD_io.fi_off
#define fb_io_len       FD.FD_io.fi_len
#define fb_io_mode      FD.FD_io.fi_mode
#define fb_io_flags     FD.FD_io.fi_flags
#define fb_io_rdev      FD.FD_io.fi_rdev

/*
 * Macros for type conversion
 * fbtod(fb,t) -        convert fusebuf pointer to data pointer of correct
 *                      type
 */
#define fbtod(fb,t)     ((t)((fb)->fb_dat))

/* flags needed by setattr */
#define FUSE_FATTR_MODE         (1 << 0)
#define FUSE_FATTR_UID          (1 << 1)
#define FUSE_FATTR_GID          (1 << 2)
#define FUSE_FATTR_SIZE         (1 << 3)
#define FUSE_FATTR_ATIME        (1 << 4)
#define FUSE_FATTR_MTIME        (1 << 5)
#define FUSE_FATTR_FH           (1 << 6)

/* fusebuf types */
#define FBT_LOOKUP      0
#define FBT_GETATTR     1
#define FBT_SETATTR     2
#define FBT_READLINK    3
#define FBT_SYMLINK     4
#define FBT_MKNOD       5
#define FBT_MKDIR       6
#define FBT_UNLINK      7
#define FBT_RMDIR       8
#define FBT_RENAME      9
#define FBT_LINK        10
#define FBT_OPEN        11
#define FBT_READ        12
#define FBT_WRITE       13
#define FBT_STATFS      14
#define FBT_RELEASE     16
#define FBT_FSYNC       17
#define FBT_FLUSH       18
#define FBT_INIT        19
#define FBT_OPENDIR     20
#define FBT_READDIR     21
#define FBT_RELEASEDIR  22
#define FBT_FSYNCDIR    23
#define FBT_ACCESS      24
#define FBT_DESTROY     26
#define FBT_RECLAIM     27

#ifdef _KERNEL

/* fusebuf prototypes */
struct  fusebuf *fb_setup(size_t, ino_t, int, struct proc *);
int     fb_queue(dev_t, struct fusebuf *);
void    fb_delete(struct fusebuf *);

#endif /* _KERNEL */
#endif /* _SYS_FUSEBUF_H_ */