jack2/common/shm.h

/* This module provides a set of abstract shared memory interfaces
 * with support using both System V and POSIX shared memory
 * implementations.  The code is divided into three sections:
 *
 *	- common (interface-independent) code
 *	- POSIX implementation
 *	- System V implementation
 *  - Windows implementation
 *
 * The implementation used is determined by whether USE_POSIX_SHM was
 * set in the ./configure step.
 */

/*
 Copyright (C) 2001-2003 Paul Davis
 Copyright (C) 2005-2012 Grame

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU Lesser General Public License as published by
 the Free Software Foundation; either version 2.1 of the License, or
 (at your option) any later version.

 This program 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 Lesser General Public License for more details.

 You should have received a copy of the GNU Lesser General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

 */

#ifndef __jack_shm_h__
#define __jack_shm_h__

#include <limits.h>
#include <sys/types.h>
#include "types.h"
#include "JackCompilerDeps.h"
#include "JackConstants.h"

#define TRUE 1
#define FALSE 0

#ifdef __cplusplus
extern "C"
{
#endif

#define MAX_SERVERS 8               /* maximum concurrent servers */
#define MAX_SHM_ID 256              /* generally about 16 per server */
#define JACK_SHM_MAGIC 0x4a41434b	/* shm magic number: "JACK" */
#define JACK_SHM_NULL_INDEX -1		/* NULL SHM index */
#define JACK_SHM_REGISTRY_INDEX -2	/* pseudo SHM index for registry */


    /* On Mac OS X, SHM_NAME_MAX is the maximum length of a shared memory
     * segment name (instead of NAME_MAX or PATH_MAX as defined by the
     * standard).
     */
#ifdef USE_POSIX_SHM

#ifndef NAME_MAX
#define NAME_MAX 255
#endif

#ifndef SHM_NAME_MAX
#define SHM_NAME_MAX NAME_MAX
#endif
    typedef char shm_name_t[SHM_NAME_MAX];
    typedef shm_name_t jack_shm_id_t;

#elif WIN32
#define NAME_MAX 255
#ifndef SHM_NAME_MAX
#define SHM_NAME_MAX NAME_MAX
#endif
    typedef char shm_name_t[SHM_NAME_MAX];
    typedef shm_name_t jack_shm_id_t;

#elif __ANDROID__

#ifndef NAME_MAX
#define NAME_MAX 255
#endif

#ifndef SHM_NAME_MAX
#define SHM_NAME_MAX NAME_MAX
#endif
    typedef char shm_name_t[SHM_NAME_MAX];
    typedef shm_name_t jack_shm_id_t;
    typedef int jack_shm_fd_t;

#else
    /* System V SHM */
    typedef int	jack_shm_id_t;
#endif /* SHM type */

    /* shared memory type */
    typedef enum {
        shm_POSIX = 1, 			/* POSIX shared memory */
        shm_SYSV = 2, 			/* System V shared memory */
        shm_WIN32 = 3,			/* Windows 32 shared memory */
        shm_ANDROID = 4			/* Android shared memory */
    } jack_shmtype_t;

#ifdef __APPLE__
    /* we need to align and pack data to 32bit so that x86_64 and arm64 work together */
    typedef int32_t jack_shm_registry_index_t;
#else
    typedef int16_t jack_shm_registry_index_t;
#endif

    /**
     * A structure holding information about shared memory allocated by
     * JACK. this persists across invocations of JACK, and can be used by
     * multiple JACK servers.  It contains no pointers and is valid across
     * address spaces.
     *
     * The registry consists of two parts: a header including an array of
     * server names, followed by an array of segment registry entries.
     */
    typedef struct _jack_shm_server {
#ifdef WIN32
        int	pid;	/* process ID */
#else
        pid_t pid;	/* process ID */
#endif

        char	name[JACK_SERVER_NAME_SIZE+1];
    }
    jack_shm_server_t;

    typedef struct _jack_shm_header {
        uint32_t	magic;	/* magic number */
        uint16_t	protocol;	/* JACK protocol version */
        jack_shmtype_t	type;	/* shm type */
        jack_shmsize_t	size;	/* total registry segment size */
        jack_shmsize_t	hdr_len;	/* size of header */
        jack_shmsize_t	entry_len; /* size of registry entry */
        jack_shm_server_t server[MAX_SERVERS]; /* current server array */
    }
    jack_shm_header_t;

    typedef struct _jack_shm_registry {
        jack_shm_registry_index_t index;     /* offset into the registry */

#ifdef WIN32
        int	allocator; /* PID that created shm segment */
#else
        pid_t allocator; /* PID that created shm segment */
#endif

        jack_shmsize_t size;      /* for POSIX unattach */
        jack_shm_id_t id;        /* API specific, see above */
#ifdef __ANDROID__
        jack_shm_fd_t fd;
#endif
    }
    jack_shm_registry_t;

#define JACK_SHM_REGISTRY_SIZE (sizeof (jack_shm_header_t) \
				+ sizeof (jack_shm_registry_t) * MAX_SHM_ID)

    /**
     * a structure holding information about shared memory
     * allocated by JACK. this version is valid only
     * for a given address space. It contains a pointer
     * indicating where the shared memory has been
     * attached to the address space.
     */

    PRE_PACKED_STRUCTURE
    struct _jack_shm_info {
        jack_shm_registry_index_t index;       /* offset into the registry */
        uint32_t size;
#ifdef __ANDROID__
        jack_shm_fd_t fd;
#endif
        union {
            void *attached_at;  /* address where attached */
            char ptr_size[8];
        } ptr;  /* a "pointer" that has the same 8 bytes size when compiling in 32 or 64 bits */
    } POST_PACKED_STRUCTURE;

    typedef struct _jack_shm_info jack_shm_info_t;

    /* utility functions used only within JACK */

    void jack_shm_copy_from_registry (jack_shm_info_t*,
                jack_shm_registry_index_t);
    void jack_shm_copy_to_registry (jack_shm_info_t*,
                                               jack_shm_registry_index_t*);
    int jack_release_shm_info (jack_shm_registry_index_t);
    char* jack_shm_addr (jack_shm_info_t* si);

    /* here begin the API */
    int jack_register_server (const char *server_name, int new_registry);
    int jack_unregister_server (const char *server_name);

    int jack_initialize_shm (const char *server_name);
    int jack_initialize_shm_server (void);
    int jack_initialize_shm_client (void);
    int jack_cleanup_shm (void);

    int jack_shmalloc (const char *shm_name, jack_shmsize_t size,
                                  jack_shm_info_t* result);
    void jack_release_shm (jack_shm_info_t*);
    void jack_release_lib_shm (jack_shm_info_t*);
    void jack_destroy_shm (jack_shm_info_t*);
    int jack_attach_shm (jack_shm_info_t*);
    int jack_attach_lib_shm (jack_shm_info_t*);
    int jack_attach_shm_read (jack_shm_info_t*);
    int jack_attach_lib_shm_read (jack_shm_info_t*);
    int jack_resize_shm (jack_shm_info_t*, jack_shmsize_t size);

#ifdef __cplusplus
}
#endif

#endif /* __jack_shm_h__ */