usr/src/lib/libc/port/nsl/t_open.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22
  23 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
  24 /*        All Rights Reserved   */
  25
  26 /*
  27  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  28  * Use is subject to license terms.
  29  */
  30
  31 #pragma ident   "%Z%%M% %I%     %E% SMI"        /* SVr4.0 1.5.3.3 */
  32
  33 #include "mt.h"
  34 #include <stdlib.h>
  35 #include <string.h>
  36 #include <strings.h>
  37 #include <unistd.h>
  38 #include <errno.h>
  39 #include <stropts.h>
  40 #include <sys/stream.h>
  41 #define _SUN_TPI_VERSION 2
  42 #include <sys/tihdr.h>
  43 #include <sys/timod.h>
  44 #include <sys/stat.h>
  45 #include <xti.h>
  46 #include <fcntl.h>
  47 #include <signal.h>
  48 #include <assert.h>
  49 #include <syslog.h>
  50 #include <limits.h>
  51 #include "tx.h"
  52
  53 /*
  54  * If _tx_open is called for transport that doesn't understand T_CAPABILITY_REQ
  55  * TPI message, call to _t_create may fail the first time it is called with
  56  * given transport (in the rare case when transport shuts down the stream with
  57  * M_ERROR in reply to unknown T_CAPABILITY_REQ). In this case we may reopen the
  58  * stream again since timod will emulate T_CAPABILITY_REQ behaviour.
  59  *
  60  * _t_create sends T_CAPABILITY_REQ through TI_CAPABILITY ioctl.
  61  */
  62
  63 int
  64 _tx_open(const char *path, int flags, struct t_info *info, int api_semantics)
  65 {
  66         int retval, fd, sv_errno;
  67         int sv_terrno;
  68         int sv_errno_global;
  69         struct _ti_user *tiptr;
  70         sigset_t mask;
  71         int t_create_first_attempt = 1;
  72         int ticap_ioctl_failed = 0;
  73
  74         if (!(flags & O_RDWR)) {
  75                 t_errno = TBADFLAG;
  76                 return (-1);
  77         }
  78
  79         sv_errno_global = errno;
  80         sv_terrno = t_errno;
  81
  82 retry:
  83         if ((fd = open(path, flags)) < 0) {
  84                 t_errno = TSYSERR;
  85                 if (_T_IS_XTI(api_semantics) && errno == ENOENT)
  86                         /* XTI only */
  87                         t_errno = TBADNAME;
  88                 return (-1);
  89         }
  90         /*
  91          * is module already pushed
  92          */
  93         do {
  94                 retval = ioctl(fd, I_FIND, "timod");
  95         } while (retval < 0 && errno == EINTR);
  96
  97         if (retval < 0) {
  98                 sv_errno = errno;
  99
 100                 t_errno = TSYSERR;
 101                 (void) close(fd);
 102                 errno = sv_errno;
 103                 return (-1);
 104         }
 105
 106         if (retval == 0) {
 107                 /*
 108                  * "timod" not already on stream, then push it
 109                  */
 110                 do {
 111                         /*
 112                          * Assumes (correctly) that I_PUSH  is
 113                          * atomic w.r.t signals (EINTR error)
 114                          */
 115                         retval = ioctl(fd, I_PUSH, "timod");
 116                 } while (retval < 0 && errno == EINTR);
 117
 118                 if (retval < 0) {
 119                         int sv_errno = errno;
 120
 121                         t_errno = TSYSERR;
 122                         (void) close(fd);
 123                         errno = sv_errno;
 124                         return (-1);
 125                 }
 126         }
 127
 128         /*
 129          * _t_create() requires that all signals be blocked.
 130          * Note that sig_mutex_lock() only defers signals, it does not
 131          * block them, so interruptible syscalls could still get EINTR.
 132          */
 133         (void) thr_sigsetmask(SIG_SETMASK, &fillset, &mask);
 134         sig_mutex_lock(&_ti_userlock);
 135         /*
 136          * Call to _t_create may fail either because transport doesn't
 137          * understand T_CAPABILITY_REQ or for some other reason. It is nearly
 138          * impossible to distinguish between these cases so it is implicitly
 139          * assumed that it is always save to close and reopen the same stream
 140          * and that open/close doesn't have side effects. _t_create may fail
 141          * only once if its' failure is caused by unimplemented
 142          * T_CAPABILITY_REQ.
 143          */
 144         tiptr = _t_create(fd, info, api_semantics, &ticap_ioctl_failed);
 145         if (tiptr == NULL) {
 146                 /*
 147                  * If _t_create failed due to fail of ti_capability_req we may
 148                  * try to reopen the stream in the hope that timod will emulate
 149                  * TI_CAPABILITY and it will succeed when called again.
 150                  */
 151                 if (t_create_first_attempt == 1 && ticap_ioctl_failed == 1) {
 152                         t_create_first_attempt = 0;
 153                         (void) close(fd);
 154                         errno = sv_errno_global;
 155                         t_errno = sv_terrno;
 156                         sig_mutex_unlock(&_ti_userlock);
 157                         (void) thr_sigsetmask(SIG_SETMASK, &mask, NULL);
 158                         goto retry;
 159                 } else {
 160                         int sv_errno = errno;
 161                         (void) close(fd);
 162                         sig_mutex_unlock(&_ti_userlock);
 163                         (void) thr_sigsetmask(SIG_SETMASK, &mask, NULL);
 164                         errno = sv_errno;
 165                         return (-1);
 166                 }
 167         }
 168
 169         /*
 170          * _t_create synchronizes state witk kernel timod and
 171          * already sets it to T_UNBND - what it needs to be
 172          * be on T_OPEN event. No _T_TX_NEXTSTATE needed here.
 173          */
 174         sig_mutex_unlock(&_ti_userlock);
 175         (void) thr_sigsetmask(SIG_SETMASK, &mask, NULL);
 176
 177         do {
 178                 retval = ioctl(fd, I_FLUSH, FLUSHRW);
 179         } while (retval < 0 && errno == EINTR);
 180
 181         /*
 182          * We ignore other error cases (retval < 0) - assumption is
 183          * that I_FLUSH failures is temporary (e.g. ENOSR) or
 184          * otherwise benign failure on a this newly opened file
 185          * descriptor and not a critical failure.
 186          */
 187
 188         return (fd);
 189 }