/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>

  This program can be distributed under the terms of the GNU LGPLv2.
  See the file COPYING.LIB.
*/

module c.fuse.fuse_common;

public import c.fuse.fuse_opt;

import core.sys.posix.config;
import core.sys.posix.sys.types;

import std.bitmanip;
import std.stdint;

enum FUSE_MAJOR_VERSION = 2;
enum FUSE_MINOR_VERSION = 9;

auto FUSE_MAKE_VERSION(Maj, Min)(Maj maj, Min min) { return ((maj) * 10 + (min)); }
enum FUSE_VERSION = FUSE_MAKE_VERSION(FUSE_MAJOR_VERSION, FUSE_MINOR_VERSION);

static assert(_FILE_OFFSET_BITS == 64);

extern (C):

/**
 * Information about open files
 *
 * Changed in version 2.5
 */
struct fuse_file_info
{
    /** Open flags. Available in open() and release() */
    int flags;

    /** Old file handle, don't use */
    c_ulong fh_old;

    /** In case of a write operation indicates if this was caused by a
      writepage */
    int writepage;

    mixin(bitfields!(
        /** Can be filled in by open, to use direct I/O on this file.
          Introduced in version 2.4 */
        uint, q{direct_io}, 1,

        /** Can be filled in by open, to indicate, that cached file data
          need not be invalidated.  Introduced in version 2.4 */
        uint, q{keep_cache}, 1,

        /** Indicates a flush operation.  Set in flush operation, also
          maybe set in highlevel lock operation and lowlevel release
          operation. Introduced in version 2.6 */
        uint, q{flush}, 1,

        /** Can be filled in by open, to indicate that the file is not
          seekable.  Introduced in version 2.8 */
        uint, q{nonseekable}, 1,

        /* Indicates that flock locks for this file should be
           released.  If set, lock_owner shall contain a valid value.
           May only be set in ->release().  Introduced in version
           2.9 */
        uint, q{flock_release}, 1,

        /** Padding.  Do not use*/
        uint, q{padding}, 27,
    ));

    /** File handle.  May be filled in by filesystem in open().
      Available in all other file operations */
    uint64_t fh;

    /** Lock owner id.  Available in locking operations and flush */
    uint64_t lock_owner;
}
version (D_LP64)
    static assert(fuse_file_info.sizeof == 40);
else
    static assert(fuse_file_info.sizeof == 32);

/**
 * Capability bits for 'fuse_conn_info.capable' and 'fuse_conn_info.want'
 *
 * FUSE_CAP_ASYNC_READ: filesystem supports asynchronous read requests
 * FUSE_CAP_POSIX_LOCKS: filesystem supports "remote" locking
 * FUSE_CAP_ATOMIC_O_TRUNC: filesystem handles the O_TRUNC open flag
 * FUSE_CAP_EXPORT_SUPPORT: filesystem handles lookups of "." and ".."
 * FUSE_CAP_BIG_WRITES: filesystem can handle write size larger than 4kB
 * FUSE_CAP_DONT_MASK: don't apply umask to file mode on create operations
 * FUSE_CAP_SPLICE_WRITE: ability to use splice() to write to the fuse device
 * FUSE_CAP_SPLICE_MOVE: ability to move data to the fuse device with splice()
 * FUSE_CAP_SPLICE_READ: ability to use splice() to read from the fuse device
 * FUSE_CAP_IOCTL_DIR: ioctl support on directories
 */
enum FUSE_CAP_ASYNC_READ = (1 << 0);
enum FUSE_CAP_POSIX_LOCKS = (1 << 1);
enum FUSE_CAP_ATOMIC_O_TRUNC = (1 << 3);
enum FUSE_CAP_EXPORT_SUPPORT = (1 << 4);
enum FUSE_CAP_BIG_WRITES = (1 << 5);
enum FUSE_CAP_DONT_MASK = (1 << 6);
enum FUSE_CAP_SPLICE_WRITE = (1 << 7);
enum FUSE_CAP_SPLICE_MOVE = (1 << 8);
enum FUSE_CAP_SPLICE_READ = (1 << 9);
enum FUSE_CAP_FLOCK_LOCKS = (1 << 10);
enum FUSE_CAP_IOCTL_DIR = (1 << 11);

/**
 * Ioctl flags
 *
 * FUSE_IOCTL_COMPAT: 32bit compat ioctl on 64bit machine
 * FUSE_IOCTL_UNRESTRICTED: not restricted to well-formed ioctls, retry allowed
 * FUSE_IOCTL_RETRY: retry with new iovecs
 * FUSE_IOCTL_DIR: is a directory
 *
 * FUSE_IOCTL_MAX_IOV: maximum of in_iovecs + out_iovecs
 */
enum FUSE_IOCTL_COMPAT = (1 << 0);
enum FUSE_IOCTL_UNRESTRICTED = (1 << 1);
enum FUSE_IOCTL_RETRY = (1 << 2);
enum FUSE_IOCTL_DIR = 	(1 << 4);

enum FUSE_IOCTL_MAX_IOV = 256;

/**
 * Connection information, passed to the ->init() method
 *
 * Some of the elements are read-write, these can be changed to
 * indicate the value requested by the filesystem.  The requested
 * value must usually be smaller than the indicated value.
 */
struct fuse_conn_info
{
    /**
     * Major version of the protocol (read-only)
     */
    uint proto_major;

    /**
     * Minor version of the protocol (read-only)
     */
    uint proto_minor;

    /**
     * Is asynchronous read supported (read-write)
     */
    uint async_read;

    /**
     * Maximum size of the write buffer
     */
    uint max_write;

    /**
     * Maximum readahead
     */
    uint max_readahead;

    /**
     * Capability flags, that the kernel supports
     */
    uint capable;

    /**
     * Capability flags, that the filesystem wants to enable
     */
    uint want;

    /**
     * Maximum number of backgrounded requests
     */
    uint max_background;

    /**
     * Kernel congestion threshold parameter
     */
    uint congestion_threshold;

    /**
     * For future use.
     */
    uint[23] reserved;
}
static assert(fuse_conn_info.sizeof == 128);

struct fuse_session;
struct fuse_chan;
struct fuse_pollhandle;

/**
 * Create a FUSE mountpoint
 *
 * Returns a control file descriptor suitable for passing to
 * fuse_new()
 *
 * @param mountpoint the mount point path
 * @param args argument vector
 * @return the communication channel on success, NULL on failure
 */
fuse_chan* fuse_mount(const char* mountpoint, fuse_args *args);

/**
 * Umount a FUSE mountpoint
 *
 * @param mountpoint the mount point path
 * @param ch the communication channel
 */
void fuse_unmount(const char* mountpoint, fuse_chan *ch);

/**
 * Parse common options
 *
 * The following options are parsed:
 *
 *   '-f'	     foreground
 *   '-d' '-odebug'  foreground, but keep the debug option
 *   '-s'	     single threaded
 *   '-h' '--help'   help
 *   '-ho'	     help without header
 *   '-ofsname=..'   file system name, if not present, then set to the program
 *		     name
 *
 * All parameters may be NULL
 *
 * @param args argument vector
 * @param mountpoint the returned mountpoint, should be freed after use
 * @param multithreaded set to 1 unless the '-s' option is present
 * @param foreground set to 1 if one of the relevant options is present
 * @return 0 on success, -1 on failure
 */
int fuse_parse_cmdline(fuse_args* args, char** mountpoint,
		       int* multithreaded, int* foreground);

/**
 * Go into the background
 *
 * @param foreground if true, stay in the foreground
 * @return 0 on success, -1 on failure
 */
int fuse_daemonize(int foreground);

/**
 * Get the version of the library
 *
 * @return the version
 */
int fuse_version();

/**
 * Destroy poll handle
 *
 * @param ph the poll handle
 */
void fuse_pollhandle_destroy(fuse_pollhandle* ph);

/* ----------------------------------------------------------- *
 * Data buffer						       *
 * ----------------------------------------------------------- */

/**
 * Buffer flags
 */
enum fuse_buf_flags
{
	/**
	 * Buffer contains a file descriptor
	 *
	 * If this flag is set, the .fd field is valid, otherwise the
	 * .mem fields is valid.
	 */
	FUSE_BUF_IS_FD		= (1 << 1),

	/**
	 * Seek on the file descriptor
	 *
	 * If this flag is set then the .pos field is valid and is
	 * used to seek to the given offset before performing
	 * operation on file descriptor.
	 */
	FUSE_BUF_FD_SEEK	= (1 << 2),

	/**
	 * Retry operation on file descriptor
	 *
	 * If this flag is set then retry operation on file descriptor
	 * until .size bytes have been copied or an error or EOF is
	 * detected.
	 */
	FUSE_BUF_FD_RETRY	= (1 << 3),
}
enum FUSE_BUF_IS_FD    = fuse_buf_flags.FUSE_BUF_IS_FD;
enum FUSE_BUF_FD_SEEK  = fuse_buf_flags.FUSE_BUF_FD_SEEK;
enum FUSE_BUF_FD_RETRY = fuse_buf_flags.FUSE_BUF_FD_RETRY;

/**
 * Buffer copy flags
 */
enum fuse_buf_copy_flags
{
	/**
	 * Don't use splice(2)
	 *
	 * Always fall back to using read and write instead of
	 * splice(2) to copy data from one file descriptor to another.
	 *
	 * If this flag is not set, then only fall back if splice is
	 * unavailable.
	 */
	FUSE_BUF_NO_SPLICE	= (1 << 1),

	/**
	 * Force splice
	 *
	 * Always use splice(2) to copy data from one file descriptor
	 * to another.  If splice is not available, return -EINVAL.
	 */
	FUSE_BUF_FORCE_SPLICE	= (1 << 2),

	/**
	 * Try to move data with splice.
	 *
	 * If splice is used, try to move pages from the source to the
	 * destination instead of copying.  See documentation of
	 * SPLICE_F_MOVE in splice(2) man page.
	 */
	FUSE_BUF_SPLICE_MOVE	= (1 << 3),

	/**
	 * Don't block on the pipe when copying data with splice
	 *
	 * Makes the operations on the pipe non-blocking (if the pipe
	 * is full or empty).  See SPLICE_F_NONBLOCK in the splice(2)
	 * man page.
	 */
	FUSE_BUF_SPLICE_NONBLOCK= (1 << 4),
}
enum FUSE_BUF_NO_SPLICE       = fuse_buf_copy_flags.FUSE_BUF_NO_SPLICE;
enum FUSE_BUF_FORCE_SPLICE    = fuse_buf_copy_flags.FUSE_BUF_FORCE_SPLICE;
enum FUSE_BUF_SPLICE_MOVE     = fuse_buf_copy_flags.FUSE_BUF_SPLICE_MOVE;
enum FUSE_BUF_SPLICE_NONBLOCK = fuse_buf_copy_flags.FUSE_BUF_SPLICE_NONBLOCK;

/**
 * Single data buffer
 *
 * Generic data buffer for I/O, extended attributes, etc...  Data may
 * be supplied as a memory pointer or as a file descriptor
 */
struct fuse_buf
{
	/**
	 * Size of data in bytes
	 */
	size_t size;

	/**
	 * Buffer flags
	 */
	fuse_buf_flags flags;

	/**
	 * Memory pointer
	 *
	 * Used unless FUSE_BUF_IS_FD flag is set.
	 */
	void* mem;

	/**
	 * File descriptor
	 *
	 * Used if FUSE_BUF_IS_FD flag is set.
	 */
	int fd;

	/**
	 * File position
	 *
	 * Used if FUSE_BUF_FD_SEEK flag is set.
	 */
	off_t pos;
}

/**
 * Data buffer vector
 *
 * An array of data buffers, each containing a memory pointer or a
 * file descriptor.
 *
 * Allocate dynamically to add more than one buffer.
 */
struct fuse_bufvec
{
	/**
	 * Number of buffers in the array
	 */
	size_t count;

	/**
	 * Index of current buffer within the array
	 */
	size_t idx;

	/**
	 * Current offset within the current buffer
	 */
	size_t off;

	/**
	 * Array of buffers
	 */
	fuse_buf[1] buf;
}

/* Initialize bufvec with a single buffer of given size */
fuse_bufvec FUSE_BUFVEC_INIT()(size_t size__)
{
    fuse_bufvec result = {
		/* .count= */ 1,
		/* .idx =  */ 0,
		/* .off =  */ 0,
		/* .buf =  */ [ /* [0] = */ {
			/* .size =  */ (size__),
			/* .flags = */ cast(fuse_buf_flags) 0,
			/* .mem =   */ null,
			/* .fd =    */ -1,
			/* .pos =   */ 0,
		} ]
	};
    return result;
}

/**
 * Get total size of data in a fuse buffer vector
 *
 * @param bufv buffer vector
 * @return size of data
 */
size_t fuse_buf_size(const fuse_bufvec* bufv);

/**
 * Copy data from one buffer vector to another
 *
 * @param dst destination buffer vector
 * @param src source buffer vector
 * @param flags flags controlling the copy
 * @return actual number of bytes copied or -errno on error
 */
ssize_t fuse_buf_copy(fuse_bufvec* dst, fuse_bufvec* src,
		      fuse_buf_copy_flags flags);

/* ----------------------------------------------------------- *
 * Signal handling					       *
 * ----------------------------------------------------------- */

/**
 * Exit session on HUP, TERM and INT signals and ignore PIPE signal
 *
 * Stores session in a global variable.	 May only be called once per
 * process until fuse_remove_signal_handlers() is called.
 *
 * @param se the session to exit
 * @return 0 on success, -1 on failure
 */
int fuse_set_signal_handlers(fuse_session* se);

/**
 * Restore default signal handlers
 *
 * Resets global session.  After this fuse_set_signal_handlers() may
 * be called again.
 *
 * @param se the same session as given in fuse_set_signal_handlers()
 */
void fuse_remove_signal_handlers(fuse_session* se);

/* ----------------------------------------------------------- *
 * Compatibility stuff					       *
 * ----------------------------------------------------------- */

/// See FuseCompat in fuse.d.
mixin template FuseCommonCompat(uint FUSE_USE_VERSION = default_FUSE_USE_VERSION)
{
    import c.fuse.fuse;
    static if (FUSE_USE_VERSION < 26)
    {
        version (FreeBSD)
        {
            static if (FUSE_USE_VERSION < 25)
                static assert(false, "On FreeBSD API version 25 or greater must be used");
        }
        import c.fuse.fuse_common_compat;
        alias fuse_unmount = fuse_unmount_compat22;
        static if (FUSE_USE_VERSION == 25)
        {
            enum FUSE_MINOR_VERSION = 5;
            alias fuse_mount = fuse_mount_compat25;
        }
        else static if (FUSE_USE_VERSION == 24 || FUSE_USE_VERSION == 22)
        {
            enum FUSE_MINOR_VERSION = 4;
            alias fuse_mount = fuse_mount_compat22;
        }
        else static if (FUSE_USE_VERSION == 21)
        {
            enum FUSE_MINOR_VERSION = 1;
            alias fuse_mount = fuse_mount_compat22;
        }
        else static if (FUSE_USE_VERSION == 11)
        {
            pragma(msg, "Compatibility with API version 11 is deprecated");
            enum FUSE_MAJOR_VERSION = 1;
            enum FUSE_MINOR_VERSION = 1;
			alias fuse_mount = fuse_mount_compat1;
		}
		else
			static assert(false, "Compatibility with API version other than 21, 22, 24, 25 and 11 not supported");
    }
}

enum default_FUSE_USE_VERSION = 21;