minix/lib/libhgfs/channel.c

   1 /* Part of libhgfs - (c) 2009, D.C. van Moolenbroek */
   2
   3 #include "inc.h"
   4
   5 #define CMD_XFER        0x1E            /* vmware backdoor transfer command */
   6
   7 enum {
   8   XFER_OPEN,                            /* open transfer channel */
   9   XFER_SENDLEN,                         /* specify length of data to send */
  10   XFER_SEND,                            /* send data */
  11   XFER_RECVLEN,                         /* get length of data to receive */
  12   XFER_RECV,                            /* receive data */
  13   XFER_RECVACK,                         /* acknowledge receipt of data */
  14   XFER_CLOSE                            /* close transfer channel */
  15 };
  16
  17 #define STATUS(p) (HIWORD((p)[2]) & 0xff)
  18
  19 /*===========================================================================*
  20  *                              channel_open                                 *
  21  *===========================================================================*/
  22 int channel_open(
  23         struct channel *ch,     /* struct describing the new channel */
  24         u32_t type              /* channel type: CH_IN or CH_OUT */
  25 )
  26 {
  27 /* Open a new backdoor channel. Upon success, the given channel structure will
  28  * be filled with information and can be used in subsequent channel calls.
  29  * Return OK on success, or a negative error code on error.
  30  */
  31   u32_t ptr[6];
  32
  33   ptr[1] = type | 0x80000000;
  34   ptr[2] = MAKELONG(CMD_XFER, XFER_OPEN);
  35
  36   backdoor(ptr);
  37
  38   if ((STATUS(ptr) & 1) == 0) return EIO;
  39
  40   ch->id = HIWORD(ptr[3]);
  41   ch->cookie1 = ptr[4];
  42   ch->cookie2 = ptr[5];
  43
  44   return OK;
  45 }
  46
  47 /*===========================================================================*
  48  *                              channel_close                                *
  49  *===========================================================================*/
  50 void channel_close(
  51         struct channel *ch      /* backdoor channel to close */
  52 )
  53 {
  54 /* Close a previously opened backdoor channel.
  55  */
  56   u32_t ptr[6];
  57
  58   ptr[2] = MAKELONG(CMD_XFER, XFER_CLOSE);
  59   ptr[3] = MAKELONG(0, ch->id);
  60   ptr[4] = ch->cookie1;
  61   ptr[5] = ch->cookie2;
  62
  63   backdoor(ptr);
  64 }
  65
  66 /*===========================================================================*
  67  *                              channel_send                                 *
  68  *===========================================================================*/
  69 int channel_send(
  70         struct channel *ch,     /* backdoor channel to send to */
  71         char *buf,              /* buffer to send data from */
  72         int len                 /* size of the data to send */
  73 )
  74 {
  75 /* Receive data over a backdoor channel. Return OK on success, or a negative
  76  * error code on error.
  77  */
  78   u32_t ptr[7];
  79
  80   ptr[1] = len;
  81   ptr[2] = MAKELONG(CMD_XFER, XFER_SENDLEN);
  82   ptr[3] = MAKELONG(0, ch->id);
  83   ptr[4] = ch->cookie1;
  84   ptr[5] = ch->cookie2;
  85
  86   backdoor(ptr);
  87
  88   if ((STATUS(ptr) & 1) == 0) return EIO;
  89
  90   if (len == 0) return OK;
  91
  92   ptr[1] = MAKELONG(0, 1);
  93   ptr[2] = len;
  94   ptr[3] = MAKELONG(0, ch->id);
  95   ptr[4] = (u32_t)buf;
  96   ptr[5] = ch->cookie2;
  97   ptr[6] = ch->cookie1;
  98
  99   backdoor_out(ptr);
 100
 101   return OK;
 102 }
 103
 104 /*===========================================================================*
 105  *                              channel_recv                                 *
 106  *===========================================================================*/
 107 int channel_recv(
 108         struct channel *ch,     /* backdoor channel to receive from */
 109         char *buf,              /* buffer to receive data into */
 110         int max                 /* size of the buffer */
 111 )
 112 {
 113 /* Receive data on a backdoor channel. Return the number of bytes received, or
 114  * a negative error code on error.
 115  */
 116   u32_t ptr[7];
 117   int len;
 118
 119   ptr[2] = MAKELONG(CMD_XFER, XFER_RECVLEN);
 120   ptr[3] = MAKELONG(0, ch->id);
 121   ptr[4] = ch->cookie1;
 122   ptr[5] = ch->cookie2;
 123
 124   backdoor(ptr);
 125
 126   if ((STATUS(ptr) & 0x81) == 0) return EIO;
 127
 128   if ((len = ptr[1]) == 0 || (STATUS(ptr) & 3) == 1) return 0;
 129
 130   if (len > max) return E2BIG;
 131
 132   ptr[1] = MAKELONG(0, 1);
 133   ptr[2] = len;
 134   ptr[3] = MAKELONG(0, ch->id);
 135   ptr[4] = ch->cookie1;
 136   ptr[5] = (u32_t)buf;
 137   ptr[6] = ch->cookie2;
 138
 139   backdoor_in(ptr);
 140
 141   ptr[1] = 1;
 142   ptr[2] = MAKELONG(CMD_XFER, XFER_RECVACK);
 143   ptr[3] = MAKELONG(0, ch->id);
 144   ptr[4] = ch->cookie1;
 145   ptr[5] = ch->cookie2;
 146
 147   backdoor(ptr);
 148
 149   return len;
 150 }