vde-2/libvdeplug/libvdeplug_dyn.h

   1 /*
   2  * libvdeplug - A library to connect to a VDE Switch.
   3  * dynamic loading version (requires libdl).
   4  *
   5  * Copyright (C) 2006,2007 Renzo Davoli, University of Bologna
   6  *
   7  * This library is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU Lesser General Public License as published by
   9  * the Free Software Foundation version 2.1 of the License, or (at
  10  * your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
  20  */
  21
  22 /* Use this include file when you need to write an application that can
  23  * benefit from vde when available.
  24  * Linking libvdeplug to your programs you force your application users
  25  * to have the library installed (otherway the dynamic linker complies
  26  * and the program does not start).
  27  *
  28  *
  29  * usage:
  30  * define a struct vdepluglib variable;
  31  * eg:
  32  *         struct vdepluglib vdeplug;
  33  *
  34  * test the availability of the library and load it:
  35  *
  36  *         libvdeplug_dynopen(vdeplug);
  37  * if vdeplug.dl_handle is not NULL the library is ready otherwise it is
  38  * not available in the target system.
  39  *
  40  * if libvdeplug does exist the library function can be called
  41  * in this way:
  42  *         libvde.vde_open(....)
  43  *         libvde.vde_read(....)
  44  *         libvde.vde_open(....)
  45  *         libvde.vde_recv(....)
  46  *         libvde.vde_send(....)
  47  *         libvde.vde_datafd(....)
  48  *         libvde.vde_ctlfd(....)
  49  *         libvde.vde_close(....)
  50  * libvdeplug_dynclose(vdeplug) can be used to deallocate the dynamic library
  51  * when needed.
  52  *************************************************/
  53
  54 #ifndef _VDEDYNLIB_H
  55 #define _VDEDYNLIB_H
  56 #include <sys/types.h>
  57 #include <dlfcn.h>
  58 #define LIBVDEPLUG_INTERFACE_VERSION 1
  59
  60 struct vdeconn;
  61
  62 typedef struct vdeconn VDECONN;
  63
  64 /* Open a VDE connection.
  65  * vde_open_options:
  66  *   port: connect to a specific port of the switch (0=any)
  67  *   group: change the ownership of the communication port to a specific group
  68  *        (NULL=no change)
  69  *   mode: set communication port mode (if 0 standard socket mode applies)
  70  */
  71 struct vde_open_args {
  72         int port;
  73         char *group;
  74         mode_t mode;
  75 };
  76
  77 /* vde_open args:
  78  *   vde_switch: switch id (path)
  79  *   descr: description (it will appear in the port description on the switch)
  80  */
  81 #define vde_open(vde_switch,descr,open_args) \
  82         vde_open_real((vde_switch),(descr),LIBVDEPLUG_INTERFACE_VERSION,(open_args))
  83
  84 struct vdepluglib {
  85         void *dl_handle;
  86         VDECONN * (*vde_open_real)(const char *vde_switch,char *descr,int interface_version, struct vde_open_args *open_args);
  87         size_t (* vde_recv)(VDECONN *conn,char *buf,size_t len,int flags);
  88         size_t (* vde_send)(VDECONN *conn,const char *buf,size_t len,int flags);
  89         int (* vde_datafd)(VDECONN *conn);
  90         int (* vde_ctlfd)(VDECONN *conn);
  91         int (* vde_close)(VDECONN *conn);
  92 };
  93
  94 typedef VDECONN * (* VDE_OPEN_REAL_T)(const char *vde_switch,char *descr,int interface_version, struct vde_open_args *open_args);
  95 typedef size_t (* VDE_RECV_T)(VDECONN *conn,char *buf,size_t len,int flags);
  96 typedef size_t (* VDE_SEND_T)(VDECONN *conn,const char *buf,size_t len,int flags);
  97 typedef int (* VDE_INT_FUN)(VDECONN *conn);
  98 #define libvdeplug_dynopen(x) ({ \
  99         (x).dl_handle=dlopen("libvdeplug.so",RTLD_NOW); \
 100         if ((x).dl_handle) { \
 101                 (x).vde_open_real=(VDE_OPEN_REAL_T) dlsym((x).dl_handle,"vde_open_real"); \
 102                 (x).vde_recv=(VDE_RECV_T) dlsym((x).dl_handle,"vde_recv"); \
 103                 (x).vde_send=(VDE_SEND_T) dlsym((x).dl_handle,"vde_send"); \
 104                 (x).vde_datafd=(VDE_INT_FUN) dlsym((x).dl_handle,"vde_datafd"); \
 105                 (x).vde_ctlfd=(VDE_INT_FUN) dlsym((x).dl_handle,"vde_ctlfd"); \
 106                 (x).vde_close=(VDE_INT_FUN) dlsym((x).dl_handle,"vde_close"); \
 107                 } else { \
 108                 (x).vde_open_real=NULL; \
 109                 (x).vde_send= NULL; \
 110                 (x).vde_recv= NULL; \
 111                 (x).vde_datafd= (x).vde_ctlfd= (x).vde_close= NULL; \
 112                 }\
 113                 })
 114
 115 #define libvdeplug_dynclose(x) ({ \
 116                 dlclose((x).dl_handle); \
 117                 })
 118
 119 #endif