fuse.h

Linux下fuse用户文件系统的的源代码

     * If this method is not implemented or under Linux kernel
     * versions earlier than 2.6.15, the mknod() and open() methods
     * will be called instead.
     *
     * Introduced in version 2.5
     */
    int (*create) (const char *, mode_t, struct fuse_file_info *);

    /**
     * Change the size of an open file
     *
     * This method is called instead of the truncate() method if the
     * truncation was invoked from an ftruncate() system call.
     *
     * If this method is not implemented or under Linux kernel
     * versions earlier than 2.6.15, the truncate() method will be
     * called instead.
     *
     * Introduced in version 2.5
     */
    int (*ftruncate) (const char *, off_t, struct fuse_file_info *);

    /**
     * Get attributes from an open file
     *
     * This method is called instead of the getattr() method if the
     * file information is available.
     *
     * Currently this is only called after the create() method if that
     * is implemented (see above).  Later it may be called for
     * invocations of fstat() too.
     *
     * Introduced in version 2.5
     */
    int (*fgetattr) (const char *, struct stat *, struct fuse_file_info *);

    /**
     * Perform POSIX file locking operation
     *
     * The cmd argument will be either F_GETLK, F_SETLK or F_SETLKW.
     *
     * For the meaning of fields in 'struct flock' see the man page
     * for fcntl(2).  The l_whence field will always be set to
     * SEEK_SET.
     *
     * For checking lock ownership, the 'fuse_file_info->owner'
     * argument must be used.
     *
     * For F_GETLK operation, the library will first check currently
     * held locks, and if a conflicting lock is found it will return
     * information without calling this method.  This ensures, that
     * for local locks the l_pid field is correctly filled in.  The
     * results may not be accurate in case of race conditions and in
     * the presence of hard links, but it's unlikly that an
     * application would rely on accurate GETLK results in these
     * cases.  If a conflicting lock is not found, this method will be
     * called, and the filesystem may fill out l_pid by a meaningful
     * value, or it may leave this field zero.
     *
     * For F_SETLK and F_SETLKW the l_pid field will be set to the pid
     * of the process performing the locking operation.
     *
     * Note: if this method is not implemented, the kernel will still
     * allow file locking to work locally.  Hence it is only
     * interesting for network filesystems and similar.
     *
     * Introduced in version 2.6
     */
    int (*lock) (const char *, struct fuse_file_info *, int cmd,
                 struct flock *);

    /**
     * Change the access and modification times of a file with
     * nanosecond resolution
     *
     * Introduced in version 2.6
     */
    int (*utimens) (const char *, const struct timespec tv[2]);

    /**
     * Map block index within file to block index within device
     *
     * Note: This makes sense only for block device backed filesystems
     * mounted with the 'blkdev' option
     *
     * Introduced in version 2.6
     */
    int (*bmap) (const char *, size_t blocksize, uint64_t *idx);
};

/** Extra context that may be needed by some filesystems
 *
 * The uid, gid and pid fields are not filled in case of a writepage
 * operation.
 */
struct fuse_context {
    /** Pointer to the fuse object */
    struct fuse *fuse;

    /** User ID of the calling process */
    uid_t uid;

    /** Group ID of the calling process */
    gid_t gid;

    /** Thread ID of the calling process */
    pid_t pid;

    /** Private filesystem data */
    void *private_data;
};

/*
 * Main function of FUSE.
 *
 * This is for the lazy.  This is all that has to be called from the
 * main() function.
 *
 * This function does the following:
 *   - parses command line options (-d -s and -h)
 *   - passes relevant mount options to the fuse_mount()
 *   - installs signal handlers for INT, HUP, TERM and PIPE
 *   - registers an exit handler to unmount the filesystem on program exit
 *   - creates a fuse handle
 *   - registers the operations
 *   - calls either the single-threaded or the multi-threaded event loop
 *
 * Note: this is currently implemented as a macro.
 *
 * @param argc the argument counter passed to the main() function
 * @param argv the argument vector passed to the main() function
 * @param op the file system operation
 * @param user_data user data set in context for init() method
 * @return 0 on success, nonzero on failure
 */
/*
int fuse_main(int argc, char *argv[], const struct fuse_operations *op,
              void *user_data);
*/
#define fuse_main(argc, argv, op, user_data) \
            fuse_main_real(argc, argv, op, sizeof(*(op)), user_data)

/* ----------------------------------------------------------- *
 * More detailed API                                           *
 * ----------------------------------------------------------- */

/**
 * Create a new FUSE filesystem.
 *
 * @param ch the communication channel
 * @param args argument vector
 * @param op the operations
 * @param op_size the size of the fuse_operations structure
 * @param user_data user data set in context for init() method
 * @return the created FUSE handle
 */
struct fuse *fuse_new(struct fuse_chan *ch, struct fuse_args *args,
                      const struct fuse_operations *op, size_t op_size,
                      void *user_data);

/**
 * Destroy the FUSE handle.
 *
 * The communication channel attached to the handle is also destroyed.
 *
 * NOTE: This function does not unmount the filesystem.  If this is
 * needed, call fuse_unmount() before calling this function.
 *
 * @param f the FUSE handle
 */
void fuse_destroy(struct fuse *f);

/**
 * FUSE event loop.
 *
 * Requests from the kernel are processed, and the appropriate
 * operations are called.
 *
 * @param f the FUSE handle
 * @return 0 if no error occurred, -1 otherwise
 */
int fuse_loop(struct fuse *f);

/**
 * Exit from event loop
 *
 * @param f the FUSE handle
 */
void fuse_exit(struct fuse *f);

/**
 * FUSE event loop with multiple threads
 *
 * Requests from the kernel are processed, and the appropriate
 * operations are called.  Request are processed in parallel by
 * distributing them between multiple threads.
 *
 * Calling this function requires the pthreads library to be linked to
 * the application.
 *
 * @param f the FUSE handle
 * @return 0 if no error occurred, -1 otherwise
 */
int fuse_loop_mt(struct fuse *f);

/**
 * Get the current context
 *
 * The context is only valid for the duration of a filesystem
 * operation, and thus must not be stored and used later.
 *
 * @return the context
 */
struct fuse_context *fuse_get_context(void);

/**
 * Check if a request has already been interrupted
 *
 * @param req request handle
 * @return 1 if the request has been interrupted, 0 otherwise
 */
int fuse_interrupted(void);

/**
 * Obsolete, doesn't do anything
 *
 * @return -EINVAL
 */
int fuse_invalidate(struct fuse *f, const char *path);

/* Deprecated, don't use */
int fuse_is_lib_option(const char *opt);

/**
 * The real main function
 *
 * Do not call this directly, use fuse_main()
 */
int fuse_main_real(int argc, char *argv[], const struct fuse_operations *op,
                   size_t op_size, void *user_data);

/* ----------------------------------------------------------- *
 * Advanced API for event handling, don't worry about this...  *
 * ----------------------------------------------------------- */

/* NOTE: the following functions are deprecated, and will be removed
   from the 3.0 API.  Use the lowlevel session functions instead */

/** Function type used to process commands */
typedef void (*fuse_processor_t)(struct fuse *, struct fuse_cmd *, void *);

/** This is the part of fuse_main() before the event loop */
struct fuse *fuse_setup(int argc, char *argv[],
                        const struct fuse_operations *op, size_t op_size,
                        char **mountpoint, int *multithreaded,
                        void *user_data);

/** This is the part of fuse_main() after the event loop */
void fuse_teardown(struct fuse *fuse, char *mountpoint);

/** Read a single command.  If none are read, return NULL */
struct fuse_cmd *fuse_read_cmd(struct fuse *f);

/** Process a single command */
void fuse_process_cmd(struct fuse *f, struct fuse_cmd *cmd);

/** Multi threaded event loop, which calls the custom command
    processor function */
int fuse_loop_mt_proc(struct fuse *f, fuse_processor_t proc, void *data);

/** Return the exited flag, which indicates if fuse_exit() has been
    called */
int fuse_exited(struct fuse *f);

/** This function is obsolete and implemented as a no-op */
void fuse_set_getcontext_func(struct fuse_context *(*func)(void));

/** Get session from fuse object */
struct fuse_session *fuse_get_session(struct fuse *f);

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

#if FUSE_USE_VERSION < 26
#  include "fuse_compat.h"
#  undef fuse_main
#  if FUSE_USE_VERSION == 25
#    define fuse_main(argc, argv, op) \
            fuse_main_real_compat25(argc, argv, op, sizeof(*(op)))
#    define fuse_new fuse_new_compat25
#    define fuse_setup fuse_setup_compat25
#    define fuse_teardown fuse_teardown_compat22
#    define fuse_operations fuse_operations_compat25
#  elif FUSE_USE_VERSION == 22
#    define fuse_main(argc, argv, op) \
            fuse_main_real_compat22(argc, argv, op, sizeof(*(op)))
#    define fuse_new fuse_new_compat22
#    define fuse_setup fuse_setup_compat22
#    define fuse_teardown fuse_teardown_compat22
#    define fuse_operations fuse_operations_compat22
#    define fuse_file_info fuse_file_info_compat
#  elif FUSE_USE_VERSION == 24
#    error Compatibility with high-level API version 24 not supported
#  else
#    define fuse_dirfil_t fuse_dirfil_t_compat
#    define __fuse_read_cmd fuse_read_cmd
#    define __fuse_process_cmd fuse_process_cmd
#    define __fuse_loop_mt fuse_loop_mt_proc
#    if FUSE_USE_VERSION == 21
#      define fuse_operations fuse_operations_compat2
#      define fuse_main fuse_main_compat2
#      define fuse_new fuse_new_compat2
#      define __fuse_setup fuse_setup_compat2
#      define __fuse_teardown fuse_teardown_compat22
#      define __fuse_exited fuse_exited
#      define __fuse_set_getcontext_func fuse_set_getcontext_func
#    else
#      define fuse_statfs fuse_statfs_compat1
#      define fuse_operations fuse_operations_compat1
#      define fuse_main fuse_main_compat1
#      define fuse_new fuse_new_compat1
#      define FUSE_DEBUG FUSE_DEBUG_COMPAT1
#    endif
#  endif
#endif

#ifdef __cplusplus
}
#endif

#endif /* _FUSE_H_ */