hurd/hurdsock.c

   1 /* _hurd_socket_server - Find the server for a socket domain.
   2    Copyright (C) 1991-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <hurd.h>
  20 #include <sys/socket.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <hurd/paths.h>
  24 #include <stdio.h>
  25 #include <_itoa.h>
  26 #include <lock-intern.h>        /* For `struct mutex'.  */
  27 #include "hurdmalloc.h"         /* XXX */
  28 #include "set-hooks.h"
  29
  30 static struct mutex lock;
  31
  32 static file_t *servers;
  33 static int max_domain = -1;
  34
  35 /* Return a port to the socket server for DOMAIN.
  36    Socket servers translate nodes in the directory _SERVERS_SOCKET
  37    (canonically /servers/socket).  These naming point nodes are named
  38    by the simplest decimal representation of the socket domain number,
  39    for example "/servers/socket/3".
  40
  41    Socket servers are assumed not to change very often.
  42    The library keeps all the server socket ports it has ever looked up,
  43    and does not look them up in /servers/socket more than once.  */
  44
  45 socket_t
  46 _hurd_socket_server (int domain, int dead)
  47 {
  48   socket_t server;
  49
  50   if (domain < 0)
  51     {
  52       errno = EAFNOSUPPORT;
  53       return MACH_PORT_NULL;
  54     }
  55
  56 retry:
  57   HURD_CRITICAL_BEGIN;
  58   __mutex_lock (&lock);
  59
  60   if (domain > max_domain)
  61     {
  62       error_t save = errno;
  63       file_t *new = realloc (servers, (domain + 1) * sizeof (file_t));
  64       if (new != NULL)
  65         {
  66           do
  67             new[++max_domain] = MACH_PORT_NULL;
  68           while (max_domain < domain);
  69           servers = new;
  70         }
  71       else
  72         /* No space to cache the port; we will just fetch it anew below.  */
  73         errno = save;
  74     }
  75
  76   if (dead && domain <= max_domain)
  77     {
  78       /* The user says the port we returned earlier (now in SERVERS[DOMAIN])
  79          was dead.  Clear the cache and fetch a new one below.  */
  80       __mach_port_deallocate (__mach_task_self (), servers[domain]);
  81       servers[domain] = MACH_PORT_NULL;
  82     }
  83
  84   if (domain > max_domain || servers[domain] == MACH_PORT_NULL)
  85     {
  86       char name[sizeof (_SERVERS_SOCKET) + 100];
  87       char *np = &name[sizeof (name)];
  88       *--np = '\0';
  89       np = _itoa (domain, np, 10, 0);
  90       *--np = '/';
  91       np -= sizeof (_SERVERS_SOCKET) - 1;
  92       memcpy (np, _SERVERS_SOCKET, sizeof (_SERVERS_SOCKET) - 1);
  93       server = __file_name_lookup (np, 0, 0);
  94       if (domain <= max_domain)
  95         servers[domain] = server;
  96     }
  97   else
  98     server = servers[domain];
  99
 100   if (server == MACH_PORT_NULL && errno == ENOENT)
 101     /* If the server node is absent, we don't support that protocol.  */
 102     errno = EAFNOSUPPORT;
 103
 104   __mutex_unlock (&lock);
 105   HURD_CRITICAL_END;
 106   if (server == MACH_PORT_NULL && errno == EINTR)
 107     /* Got a signal while inside an RPC of the critical section, retry again */
 108     goto retry;
 109
 110   return server;
 111 }
 112 \f
 113 static void attribute_used_retain
 114 init (void)
 115 {
 116   int i;
 117
 118   __mutex_init (&lock);
 119
 120   for (i = 0; i < max_domain; ++i)
 121     servers[i] = MACH_PORT_NULL;
 122 }
 123 SET_RELHOOK (_hurd_preinit_hook, init);