lib/libhgfs/rpc.c

   1 /* Part of libhgfs - (c) 2009, D.C. van Moolenbroek */
   2
   3 #include "inc.h"
   4
   5 char rpc_buf[RPC_BUF_SIZE];
   6 char *rpc_ptr;
   7
   8 static struct channel rpc_chan;
   9
  10 /*===========================================================================*
  11  *                              rpc_open                                     *
  12  *===========================================================================*/
  13 int rpc_open()
  14 {
  15 /* Open a HGFS RPC backdoor channel to the VMware host, and make sure that it
  16  * is working. Return OK upon success, or a negative error code otherwise; in
  17  * particular, return EAGAIN if shared folders are disabled.
  18  */
  19   int r;
  20
  21   if ((r = channel_open(&rpc_chan, CH_OUT)) != OK)
  22         return r;
  23
  24   r = rpc_test();
  25
  26   if (r != OK)
  27         channel_close(&rpc_chan);
  28
  29   return r;
  30 }
  31
  32 /*===========================================================================*
  33  *                              rpc_query                                    *
  34  *===========================================================================*/
  35 int rpc_query()
  36 {
  37 /* Send a HGFS RPC query over the backdoor channel. Return OK upon success, or
  38  * a negative error code otherwise; EAGAIN is returned if shared folders are
  39  * disabled. In general, we make the assumption that the sender (= VMware)
  40  * speaks the protocol correctly. Hence, the callers of this function do not
  41  * check for lengths.
  42  */
  43   int r, len, id, err;
  44
  45   len = RPC_LEN;
  46
  47   /* A more robust version of this call could reopen the channel and
  48    * retry the request upon low-level failure.
  49    */
  50   r = channel_send(&rpc_chan, rpc_buf, len);
  51   if (r < 0) return r;
  52
  53   r = channel_recv(&rpc_chan, rpc_buf, sizeof(rpc_buf));
  54   if (r < 0) return r;
  55   if (r < 2 || (len > 2 && r < 10)) return EIO;
  56
  57   RPC_RESET;
  58
  59   if (RPC_NEXT8 != '1') return EAGAIN;
  60   if (RPC_NEXT8 != ' ') return EAGAIN;
  61
  62   if (len <= 2) return OK;
  63
  64   id = RPC_NEXT32;
  65   err = RPC_NEXT32;
  66
  67   return error_convert(err);
  68 }
  69
  70 /*===========================================================================*
  71  *                              rpc_test                                     *
  72  *===========================================================================*/
  73 int rpc_test()
  74 {
  75 /* Test whether HGFS communication is working. Return OK on success, EAGAIN if
  76  * shared folders are disabled, or another negative error code upon error.
  77  */
  78
  79   RPC_RESET;
  80   RPC_NEXT8 = 'f';
  81   RPC_NEXT8 = ' ';
  82
  83   return rpc_query();
  84 }
  85
  86 /*===========================================================================*
  87  *                              rpc_close                                    *
  88  *===========================================================================*/
  89 void rpc_close()
  90 {
  91 /* Close the HGFS RPC backdoor channel.
  92  */
  93
  94   channel_close(&rpc_chan);
  95 }