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      1 /*
      2  * Copyright (C) 2008 The Android Open Source Project
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  *  * Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  *  * Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in
     12  *    the documentation and/or other materials provided with the
     13  *    distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     16  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     17  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     18  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
     19  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
     20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
     21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
     22  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
     25  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  */
     28 #include <errno.h>
     29 #include <signal.h>
     30 #include <string.h>
     31 #include <time.h>
     32 
     33 int __rt_sigtimedwait(const sigset_t *uthese, siginfo_t *uinfo, const struct timespec *uts, size_t sigsetsize);
     34 
     35 /* ok, this is really subtle: <asm/signal.h> defines sigset_t differently
     36  * when you're in the kernel or in the C library.
     37  *
     38  * in the kernel, this is an array of 2 32-bit unsigned longs
     39  * in the C library, this is a single 32-bit unsigned long
     40  *
     41  * moreover, the kernel implementation of rt_sigtimedwait doesn't
     42  * accept anything except kernel-sized signal sets (probably a bug !)
     43  *
     44  * we thus need to create a fake kernel sigset !!
     45  */
     46 
     47 int sigwait(const sigset_t *set, int *sig)
     48 {
     49     int  ret;
     50 #ifdef __mips__
     51     /* use a union to get rid of aliasing warnings. On MIPS sigset_t is 128 bits */
     52     union {
     53       sigset_t       kernel_sigset;
     54       sigset_t       dummy_sigset;
     55     } u;
     56     u.dummy_sigset = *set;
     57 #else
     58     /* use a union to get rid of aliasing warnings */
     59     union {
     60       unsigned long  kernel_sigset[2];
     61       sigset_t       dummy_sigset;
     62     } u;
     63 
     64     u.kernel_sigset[0] = *set;
     65     u.kernel_sigset[1] = 0;  /* no real-time signals supported ? */
     66 #endif
     67     for (;;)
     68     {
     69      /* __rt_sigtimedwait can return EAGAIN or EINTR, we need to loop
     70       * around them since sigwait is only allowed to return EINVAL
     71       */
     72       ret = __rt_sigtimedwait ( &u.dummy_sigset, NULL, NULL, sizeof(u.kernel_sigset));
     73       if (ret >= 0)
     74         break;
     75 
     76       if (errno != EAGAIN && errno != EINTR)
     77         return errno;
     78     }
     79 
     80     *sig = ret;
     81     return 0;
     82 }
     83 
     84