lib/libsffs/main.c

   1 /* This file contains the SFFS initialization code and message loop.
   2  *
   3  * The entry points into this file are:
   4  *   sffs_init          initialization
   5  *   sffs_signal        signal handler
   6  *   sffs_loop          main message loop
   7  *
   8  * Created:
   9  *   April 2009 (D.C. van Moolenbroek)
  10  */
  11
  12 #include "inc.h"
  13
  14 /*===========================================================================*
  15  *                              sffs_init                                    *
  16  *===========================================================================*/
  17 int sffs_init(char *name, const struct sffs_table *table,
  18   struct sffs_params *params)
  19 {
  20 /* Initialize this file server. Called at startup time.
  21  */
  22   int i;
  23
  24   /* Make sure that the given path prefix doesn't end with a slash. */
  25   i = strlen(params->p_prefix);
  26   while (i > 0 && params->p_prefix[i - 1] == '/') i--;
  27   params->p_prefix[i] = 0;
  28
  29   state.s_mounted = FALSE;
  30   state.s_signaled = FALSE;
  31
  32   sffs_name = name;
  33   sffs_table = table;
  34   sffs_params = params;
  35
  36   return OK;
  37 }
  38
  39 /*===========================================================================*
  40  *                              sffs_signal                                  *
  41  *===========================================================================*/
  42 void sffs_signal(int signo)
  43 {
  44
  45   /* Only check for termination signal, ignore anything else. */
  46   if (signo != SIGTERM) return;
  47
  48   /* We can now terminate if we have also been unmounted. */
  49   state.s_signaled = TRUE;
  50
  51   if (state.s_mounted) {
  52         dprintf(("%s: got SIGTERM, still mounted\n", sffs_name));
  53   } else {
  54         dprintf(("%s: got SIGTERM, shutting down\n", sffs_name));
  55
  56         /* Break out of the main loop, giving the main program the chance to
  57          * perform further cleanup. This causes sef_receive() to return with
  58          * an EINTR error code.
  59          */
  60         sef_cancel();
  61   }
  62 }
  63
  64 /*===========================================================================*
  65  *                              get_work                                     *
  66  *===========================================================================*/
  67 static int get_work(who_e)
  68 endpoint_t *who_e;
  69 {
  70 /* Receive a request message from VFS. Return TRUE if a new message is ready
  71  * to be processed, or FALSE if sef_stop() was called from the signal handler.
  72  */
  73   int r;
  74
  75   if ((r = sef_receive(ANY, &m_in)) != OK) {
  76         if (r != EINTR)
  77                 panic("receive failed: %d", r);
  78
  79         return FALSE;
  80   }
  81
  82   *who_e = m_in.m_source;
  83   return TRUE;
  84 }
  85
  86 /*===========================================================================*
  87  *                              send_reply                                   *
  88  *===========================================================================*/
  89 static void send_reply(err, transid)
  90 int err;                                /* resulting error code */
  91 int transid;
  92 {
  93 /* Send a reply message to the requesting party, with the given error code.
  94  */
  95   int r;
  96
  97   m_out.m_type = err;
  98   if (IS_VFS_FS_TRANSID(transid)) {
  99         /* If a transaction ID was set, reset it */
 100         m_out.m_type = TRNS_ADD_ID(m_out.m_type, transid);
 101   }
 102   if ((r = send(m_in.m_source, &m_out)) != OK)
 103         printf("%s: send failed (%d)\n", sffs_name, r);
 104 }
 105
 106 /*===========================================================================*
 107  *                              sffs_loop                                    *
 108  *===========================================================================*/
 109 void sffs_loop(void)
 110 {
 111 /* The main function of this file server. After initializing, loop, receiving
 112  * one request from VFS at a time, processing it, and sending a reply back to
 113  * VFS. Termination occurs when we both have been unmounted and have received
 114  * a termination signal.
 115  */
 116   endpoint_t who_e;
 117   int call_nr, err, transid;
 118
 119   while (state.s_mounted || !state.s_signaled) {
 120         if (!get_work(&who_e))
 121                 continue;       /* Recheck running conditions */
 122
 123         transid = TRNS_GET_ID(m_in.m_type);
 124         m_in.m_type = TRNS_DEL_ID(m_in.m_type);
 125         if (m_in.m_type == 0) {
 126                 assert(!IS_VFS_FS_TRANSID(transid));
 127                 m_in.m_type = transid;          /* Backwards compat. */
 128                 transid = 0;
 129         } else
 130                 assert(IS_VFS_FS_TRANSID(transid));
 131
 132         call_nr = m_in.m_type;
 133         if (who_e != VFS_PROC_NR) {
 134                 continue;
 135         }
 136
 137         if (state.s_mounted || call_nr == REQ_READSUPER) {
 138                 call_nr -= VFS_BASE;
 139
 140                 dprintf(("%s: call %d\n", sffs_name, call_nr));
 141
 142                 if (call_nr >= 0 && call_nr < NREQS) {
 143                         err = (*call_vec[call_nr])();
 144                 } else {
 145                         err = ENOSYS;
 146                 }
 147
 148                 dprintf(("%s: call %d result %d\n", sffs_name, call_nr, err));
 149         }
 150         else err = EINVAL;
 151
 152         send_reply(err, transid);
 153   }
 154 }