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      1 /* $NetBSD: refuse_log.c,v 1.2 2022/01/29 00:03:41 tnn Exp $ */
      2 
      3 /*
      4  * Copyright (c) 2021 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. The name of the author may not be used to endorse or promote
     16  *    products derived from this software without specific prior written
     17  *    permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
     20  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     21  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
     23  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
     25  * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     27  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
     28  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     29  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if !defined(lint)
     34 __RCSID("$NetBSD: refuse_log.c,v 1.2 2022/01/29 00:03:41 tnn Exp $");
     35 #endif /* !lint */
     36 
     37 #include <assert.h>
     38 #include <fuse_log.h>
     39 #if defined(MULTITHREADED_REFUSE)
     40 #	include <pthread.h>
     41 #endif
     42 #include <stdio.h>
     43 
     44 static void  __printflike(2, 0)
     45 default_log_func(enum fuse_log_level level __attribute__((__unused__)),
     46                  const char *fmt, va_list ap) {
     47     /* This function needs to be thread-safe. Calling vfprintf(3)
     48      * should be okay because POSIX mandates locking FILE* objects
     49      * internally. */
     50     vfprintf(stderr, fmt, ap);
     51 }
     52 
     53 #if defined(MULTITHREADED_REFUSE)
     54 static pthread_mutex_t	log_func_mutex = PTHREAD_MUTEX_INITIALIZER;
     55 #endif
     56 static fuse_log_func_t	log_func = default_log_func;
     57 
     58 void
     59 fuse_set_log_func(fuse_log_func_t func) {
     60 #if defined(MULTITHREADED_REFUSE)
     61     /* What we really need here is merely a memory barrier, but
     62      * locking a mutex is the easiest way to achieve that. */
     63     int rv;
     64 
     65     rv = pthread_mutex_lock(&log_func_mutex);
     66     assert(rv == 0);
     67 #endif
     68 
     69     if (func)
     70         log_func = func;
     71     else
     72         log_func = default_log_func;
     73 
     74 #if defined(MULTITHREADED_REFUSE)
     75     rv = pthread_mutex_unlock(&log_func_mutex);
     76     assert(rv == 0);
     77 #endif
     78 }
     79 
     80 void
     81 fuse_log(enum fuse_log_level level, const char *fmt, ...) {
     82     va_list ap;
     83 #if defined(MULTITHREADED_REFUSE)
     84     /* What we really need here is merely a memory barrier, but
     85      * locking a mutex is the easiest way to achieve that. */
     86     int rv;
     87 
     88     rv = pthread_mutex_lock(&log_func_mutex);
     89     assert(rv == 0);
     90 #endif
     91 
     92     va_start(ap, fmt);
     93     log_func(level, fmt, ap);
     94     va_end(ap);
     95 
     96 #if defined(MULTITHREADED_REFUSE)
     97     rv = pthread_mutex_unlock(&log_func_mutex);
     98     assert(rv == 0);
     99 #endif
    100 }
    101