source: libwandio/wandio.h @ c909fad

/*
 * This file is part of libtrace
 *
 * Copyright (c) 2007,2008,2009,2010 The University of Waikato, Hamilton, 
 * New Zealand.
 *
 * Authors: Daniel Lawson 
 *          Perry Lorier
 *          Shane Alcock 
 *          
 * All rights reserved.
 *
 * This code has been developed by the University of Waikato WAND 
 * research group. For further information please see http://www.wand.net.nz/
 *
 * libtrace is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * libtrace is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with libtrace; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * $Id$
 *
 */

#ifndef IO_H 
#define IO_H 1 /**< Guard Define */
#include "config.h"
#include <sys/types.h>
#include <stdio.h>
#include <inttypes.h>
#include <stdbool.h>

#if __GNUC__ >= 4
        #ifdef LT_BUILDING_DLL
                #define DLLEXPORT __attribute__ ((visibility("default")))
                #define DLLLOCAL __attribute__ ((visibility("hidden")))
        #else
                #define DLLEXPORT
                #define DLLLOCAL
        #endif
#else
        #define DLLEXPORT
        #define DLLLOCAL
#endif

#if __GNUC__ >= 3 
#  define DEPRECATED __attribute__((deprecated))
#  define SIMPLE_FUNCTION __attribute__((pure))
#  define UNUSED __attribute__((unused))
#  define PACKED __attribute__((packed))
#  define PRINTF(formatpos,argpos) __attribute__((format(printf,formatpos,argpos)))
#else
#  define DEPRECATED
#  define SIMPLE_FUNCTION
#  define UNUSED
#  define PACKED 
#  define PRINTF(formatpos,argpos) 
#endif


/** @file
 *
 * @brief Header file dealing with the Libtrace IO sub-system
 *
 * @author Perry Lorier
 * @author Shane Alcock
 *
 * @version $Id$
 */

typedef struct io_t io_t; /**< Opaque IO handle structure for reading */
typedef struct iow_t iow_t; /**< Opaque IO handle structure for writing */

/** Structure defining a supported compression method */
struct compression_type {
        /** Name of the compression method */
        const char *name;
        /** Extension to add to the filename of files written using this 
         *  method */
        const char *ext;
        /** Internal type identifying the compression method */
        int compress_type;
};

/** The list of supported compression methods */
extern struct compression_type compression_type[];

/** Structure defining a libtrace IO reader module */
typedef struct {
        /** Module name */
        const char *name;

        /** Reads from the IO source into the provided buffer.
         *
         * @param io            The IO reader
         * @param buffer        The buffer to read into
         * @param len           The amount of space available in the buffer
         * @return The amount of bytes read, 0 if end of file is reached, -1
         * if an error occurs
         */
        off_t (*read)(io_t *io, void *buffer, off_t len);

        /** Reads from the IO source into the provided buffer but does not
         *  advance the read pointer.
         *
         * @param io            The IO reader
         * @param buffer        The buffer to read into
         * @param len           The amount of space available in the buffer
         * @return The amount of bytes read, 0 if end of file is reached, -1
         * if an error occurs
         */
        off_t (*peek)(io_t *io, void *buffer, off_t len);

        /** Returns the current offset of the read pointer for an IO source.
         *
         * @param io            The IO reader to get the read offset for
         * @return The offset of the read pointer, or -1 if an error occurs
         */
        off_t (*tell)(io_t *io);
        
        /** Moves the read pointer for an IO source.
         * 
         * @param io            The IO reader to move the read pointer for
         * @param offset        The new read pointer offset
         * @param whence        Where to start counting the new offset from.
         *                      whence can be one of three values: SEEK_SET,
         *                      SEEK_CUR and SEEK_END. See the lseek(2) manpage
         *                      for more details as to what these mean.
         * @return The value of the new read pointer, or -1 if an error occurs
         */
        off_t (*seek)(io_t *io, off_t offset, int whence);
        
        /** Closes an IO reader. This function should free the IO reader.
         *
         * @param io            The IO reader to close
         */
        void (*close)(io_t *io);
} io_source_t;

/** Structure defining a libtrace IO writer module */
typedef struct {
        /** The name of the module */
        const char *name;
        
        /** Writes the contents of a buffer using an IO writer.
         *
         * @param iow           The IO writer to write the data with
         * @param buffer        The buffer to be written
         * @param len           The amount of writable data in the buffer
         * @return The amount of data written, or -1 if an error occurs
         */
        off_t (*write)(iow_t *iow, const char *buffer, off_t len);

        /** Closes an IO writer. This function should free the IO writer. 
         *
         * @param iow           The IO writer to close
         */
        void (*close)(iow_t *iow);
} iow_source_t;

/** A libtrace IO reader */
struct io_t {
        /** The IO module that is used by the reader */
        io_source_t *source;
        /** Generic pointer to data required by the IO module */
        void *data;
};

/** A libtrace IO writer */
struct iow_t {
        /** The IO module that is used by the writer */
        iow_source_t *source;
        /** Generic pointer to data required by the IO module */
        void *data;
};

/** Enumeration of all supported compression methods */
enum {
        /** No compression */
        WANDIO_COMPRESS_NONE    = 0,
        /** Zlib compression */
        WANDIO_COMPRESS_ZLIB    = 1,
        /** Bzip compression */
        WANDIO_COMPRESS_BZ2     = 2,
        /** LZO compression */
        WANDIO_COMPRESS_LZO     = 3,
        /** All supported methods - used as a bitmask */
        WANDIO_COMPRESS_MASK    = 7
};

/** @name IO open functions
 *
 * These functions deal with creating and initialising a new IO reader or 
 * writer.
 *
 * @{
 */

io_t *bz_open(io_t *parent);
io_t *zlib_open(io_t *parent);
io_t *thread_open(io_t *parent);
io_t *peek_open(io_t *parent);
io_t *stdio_open(const char *filename);

iow_t *zlib_wopen(iow_t *child, int compress_level);
iow_t *bz_wopen(iow_t *child, int compress_level);
iow_t *lzo_wopen(iow_t *child, int compress_level);
iow_t *thread_wopen(iow_t *child);
iow_t *stdio_wopen(const char *filename, int fileflags);

/* @} */

/**
 * @name Libtrace IO API functions
 *
 * These are the functions that should be called by the format modules to open
 * and use files with the libtrace IO sub-system.
 *
 * @{ */

/** Creates a new libtrace IO reader and opens the provided file for reading.
 *
 * @param filename      The name of the file to open
 * @return A pointer to a new libtrace IO reader, or NULL if an error occurs
 *
 * This function will attempt to detect the compression format used for the
 * given file (if any), provided that libtrace was built with the appropriate
 * libraries.
 */
io_t *wandio_create(const char *filename);

/** Returns the current offset of the read pointer for a libtrace IO reader. 
 *
 * @param io            The IO reader to get the read offset for
 * @return The offset of the read pointer, or -1 if an error occurs
 */
off_t wandio_tell(io_t *io);

/** Changes the read pointer offset to the specified value for a libtrace IO
 * reader.
 *
 * @param io            The IO reader to adjust the read pointer for
 * @param offset        The new offset for the read pointer
 * @param whence        Indicates where to set the read pointer from. Can be 
 *                      one of SEEK_SET, SEEK_CUR or SEEK_END.
 * @return The new value for the read pointer, or -1 if an error occurs
 *
 * The arguments for this function are the same as those for lseek(2). See the
 * lseek(2) manpage for more details.
 */
off_t wandio_seek(io_t *io, off_t offset, int whence);

/** Reads from a libtrace IO reader into the provided buffer.
 *
 * @param io            The IO reader to read from
 * @param buffer        The buffer to read into
 * @param len           The size of the buffer
 * @return The amount of bytes read, 0 if EOF is reached, -1 if an error occurs
 */
off_t wandio_read(io_t *io, void *buffer, off_t len);

/** Reads from a libtrace IO reader into the provided buffer, but does not
 * update the read pointer.
 *
 * @param io            The IO reader to read from
 * @param buffer        The buffer to read into
 * @param len           The size of the buffer
 * @return The amount of bytes read, 0 if EOF is reached, -1 if an error occurs
 */
off_t wandio_peek(io_t *io, void *buffer, off_t len);

/** Destroys a libtrace IO reader, closing the file and freeing the reader
 * structure.
 *
 * @param io            The IO reader to destroy
 */
void wandio_destroy(io_t *io);

/** Creates a new libtrace IO writer and opens the provided file for writing.
 *
 * @param filename              The name of the file to open
 * @param compression_type      Compression type
 * @param compression_level     The compression level to use when writing
 * @param flags                 Flags to apply when opening the file, e.g.
 *                              O_CREATE
 * @return A pointer to the new libtrace IO writer, or NULL if an error occurs
 */
iow_t *wandio_wcreate(const char *filename, int compression_type, int compression_level, int flags);

/** Writes the contents of a buffer using a libtrace IO writer.
 *
 * @param iow           The IO writer to write the data with
 * @param buffer        The buffer to write out
 * @param len           The amount of writable data in the buffer
 * @return The amount of data written, or -1 if an error occurs
 */
off_t wandio_wwrite(iow_t *iow, const void *buffer, off_t len);

/** Destroys a libtrace IO writer, closing the file and freeing the writer
 * structure.
 *
 * @param iow           The IO writer to destroy
 */
void wandio_wdestroy(iow_t *iow);

/** @} */

/** @name libtraceio options 
 * @{ */
extern int force_directio_read;
extern int force_directio_write;
extern uint64_t write_waits;
extern uint64_t read_waits;
extern unsigned int use_threads;
extern unsigned int max_buffers;
/* @} */

#endif