libdaemon/client/daemon-client.h

   1 /*
   2  * Copyright (C) 2011-2012 Red Hat, Inc.
   3  *
   4  * This file is part of LVM2.
   5  *
   6  * This copyrighted material is made available to anyone wishing to use,
   7  * modify, copy, or redistribute it subject to the terms and conditions
   8  * of the GNU Lesser General Public License v.2.1.
   9  *
  10  * You should have received a copy of the GNU Lesser General Public License
  11  * along with this program; if not, write to the Free Software Foundation,
  12  * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  13  */
  14
  15 #ifndef _LVM_DAEMON_COMMON_CLIENT_H
  16 #define _LVM_DAEMON_COMMON_CLIENT_H
  17
  18 #include "libdevmapper.h"
  19
  20 typedef struct {
  21         int socket_fd; /* the fd we use to talk to the daemon */
  22         const char *protocol;
  23         int protocol_version;  /* version of the protocol the daemon uses */
  24         int error;
  25 } daemon_handle;
  26
  27 typedef struct {
  28         const char *path; /* the binary of the daemon */
  29         const char *socket; /* path to the comms socket */
  30         unsigned autostart:1; /* start the daemon if not running? */
  31
  32         /*
  33          * If the following are not NULL/0, an attempt to talk to a daemon which
  34          * uses a different protocol or version will fail.
  35          */
  36         const char *protocol;
  37         int protocol_version;
  38 } daemon_info;
  39
  40 typedef struct {
  41         char *buffer;
  42         /*
  43          * The request looks like this:
  44          *    request = "id"
  45          *    arg_foo = "something"
  46          *    arg_bar = 3
  47          *    arg_wibble {
  48          *        something_special = "here"
  49          *        amount = 75
  50          *        knobs = [ "twiddle", "tweak" ]
  51          *    }
  52          */
  53         struct dm_config_tree *cft;
  54 } daemon_request;
  55
  56 typedef struct {
  57         int error; /* 0 for success */
  58         char *buffer; /* textual reply */
  59         struct dm_config_tree *cft; /* parsed reply, if available */
  60 } daemon_reply;
  61
  62 /*
  63  * Open the communication channel to the daemon. If the daemon is not running,
  64  * it may be autostarted based on the binary path provided in the info (this
  65  * will only happen if autostart is set to true). If the call fails for any
  66  * reason, daemon_handle_valid(h) for the response will return false. Otherwise,
  67  * the connection is good to start serving requests.
  68  */
  69 daemon_handle daemon_open(daemon_info i);
  70
  71 /*
  72  * Send a request to the daemon, waiting for the reply. All communication with
  73  * the daemon is synchronous. The function handles the IO details and parses the
  74  * response, handling common error conditions. See "daemon_reply" for details.
  75  *
  76  * In case the request contains a non-NULL buffer pointer, this buffer is sent
  77  * *verbatim* to the server. In this case, the cft pointer may be NULL (but will
  78  * be ignored even if non-NULL). If the buffer is NULL, the cft is required to
  79  * be a valid pointer, and is used to build up the request.
  80  */
  81 daemon_reply daemon_send(daemon_handle h, daemon_request r);
  82
  83 /*
  84  * A simple interface to daemon_send. This function just takes the command id
  85  * and possibly a list of parameters (of the form "name = %?", "value"). The
  86  * type (string, integer) of the value is indicated by a character substituted
  87  * for ? in %?: d for integer, s for string.
  88  */
  89 daemon_reply daemon_send_simple(daemon_handle h, const char *id, ...);
  90
  91 void daemon_reply_destroy(daemon_reply r);
  92
  93 static inline int daemon_reply_int(daemon_reply r, const char *path, int def) {
  94         return dm_config_find_int(r.cft->root, path, def);
  95 }
  96
  97 static inline const char *daemon_reply_str(daemon_reply r, const char *path, const char *def) {
  98         return dm_config_find_str(r.cft->root, path, def);
  99 }
 100
 101
 102 /* Shut down the communication to the daemon. Compulsory. */
 103 void daemon_close(daemon_handle h);
 104
 105 #endif