server/log.c

   1 /* nbdkit
   2  * Copyright (C) 2013-2018 Red Hat Inc.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
   7  *
   8  * * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *
  11  * * Redistributions in binary form must reproduce the above copyright
  12  * notice, this list of conditions and the following disclaimer in the
  13  * documentation and/or other materials provided with the distribution.
  14  *
  15  * * Neither the name of Red Hat nor the names of its contributors may be
  16  * used to endorse or promote products derived from this software without
  17  * specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  21  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  22  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
  23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  26  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  27  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  28  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  29  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #include <config.h>
  34
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <stdarg.h>
  38 #include <string.h>
  39 #include <errno.h>
  40
  41 #include "internal.h"
  42
  43 /* Call the right nbdkit_verror function depending on log_sink.
  44  * Note: preserves the previous value of errno.
  45  */
  46 void
  47 nbdkit_verror (const char *fs, va_list args)
  48 {
  49   switch (log_to) {
  50   case LOG_TO_DEFAULT:
  51     if (forked_into_background)
  52       log_syslog_verror (fs, args);
  53     else
  54       log_stderr_verror (fs, args);
  55     break;
  56   case LOG_TO_SYSLOG:
  57     log_syslog_verror (fs, args);
  58     break;
  59   case LOG_TO_STDERR:
  60     log_stderr_verror (fs, args);
  61     break;
  62   case LOG_TO_NULL:
  63     /* nothing */
  64     break;
  65   }
  66 }
  67
  68 /* Wrapper around nbdkit_verror.
  69  * Note: preserves the previous value of errno.
  70  */
  71 void
  72 nbdkit_error (const char *fs, ...)
  73 {
  74   va_list args;
  75
  76   va_start (args, fs);
  77   nbdkit_verror (fs, args);
  78   va_end (args);
  79 }
  80
  81 #if !HAVE_VFPRINTF_PERCENT_M
  82 /* Work around lack of %m in BSD */
  83 #undef vfprintf
  84
  85 /* Call the real vfprintf after first changing %m into strerror(errno). */
  86 int
  87 nbdkit_vfprintf(FILE *f, const char *fmt, va_list args)
  88 {
  89   char *repl = NULL;
  90   char *p = strstr (fmt, "%m"); /* assume strstr doesn't touch errno */
  91   int ret;
  92
  93   /* We only handle the first %m; if a user passes more than one, they
  94    * deserve broken output.
  95    */
  96   if (p && asprintf (&repl, "%.*s%s%s", (int) (p - fmt), fmt, strerror (errno),
  97                      p + 2) > 0)
  98     fmt = repl;
  99   ret = vfprintf (f, fmt, args);
 100   free (repl);
 101   return ret;
 102 }
 103 #endif