NAME

       explain_settimeofday - explain settimeofday(2) errors

SYNOPSIS

       #include <libexplain/settimeofday.h>
       const char *explain_settimeofday(const struct timeval *tv, const struct timezone *tz);
       const char *explain_errno_settimeofday(int errnum, const struct timeval *tv, const struct
       timezone *tz);
       void explain_message_settimeofday(char *message, int message_size, const struct timeval
       *tv, const struct timezone *tz);
       void explain_message_errno_settimeofday(char *message, int message_size, int errnum, const
       struct timeval *tv, const struct timezone *tz);

DESCRIPTION

       These  functions  may  be  used  to  obtain  explanations  for  errors  returned  by   the
       settimeofday(2) system call.

   explain_settimeofday
       const char *explain_settimeofday(const struct timeval *tv, const struct timezone *tz);

       The explain_settimeofday function is used to obtain an explanation of an error returned by
       the settimeofday(2) system call. The least the  message  will  contain  is  the  value  of
       strerror(errno),  but usually it will do much better, and indicate the underlying cause in
       more detail.

       The errno global variable will be used to obtain the error value to be decoded.

       tv      The original tv, exactly as passed to the settimeofday(2) system call.

       tz      The original tz, exactly as passed to the settimeofday(2) system call.

       Returns:
               The message explaining the error. This message buffer is shared by all  libexplain
               functions  which  do  not  supply  a  buffer in their argument list.  This will be
               overwritten by the next call to any libexplain function which shares this  buffer,
               including other threads.

       Note:  This  function  is  not  thread  safe, because it shares a return buffer across all
       threads, and many other functions in this library.

       Example: This function is intended to be used  in  a  fashion  similar  to  the  following
       example:
              if (settimeofday(tv, tz) < 0)
              {
                  fprintf(stderr, "%s\n", explain_settimeofday(tv, tz));
                  exit(EXIT_FAILURE);
              }

       The  above  code  example  is available pre-packaged as the explain_settimeofday_or_die(3)
       function.

   explain_errno_settimeofday
       const char *explain_errno_settimeofday(int errnum, const struct timeval *tv, const struct
       timezone *tz);

       The  explain_errno_settimeofday  function  is  used  to  obtain an explanation of an error
       returned by the settimeofday(2) system call. The least the message  will  contain  is  the
       value  of strerror(errno), but usually it will do much better, and indicate the underlying
       cause in more detail.

       errnum  The error value to be decoded, usually obtained from  the  errno  global  variable
               just  before  this  function  is called. This is necessary if you need to call any
               code between the system call to be explained and this function, because many  libc
               functions will alter the value of errno.

       tv      The original tv, exactly as passed to the settimeofday(2) system call.

       tz      The original tz, exactly as passed to the settimeofday(2) system call.

       Returns:
               The  message explaining the error. This message buffer is shared by all libexplain
               functions which do not supply a buffer in  their  argument  list.   This  will  be
               overwritten  by the next call to any libexplain function which shares this buffer,
               including other threads.

       Note: This function is not thread safe, because it  shares  a  return  buffer  across  all
       threads, and many other functions in this library.

       Example:  This  function  is  intended  to  be  used in a fashion similar to the following
       example:
              if (settimeofday(tv, tz) < 0)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_settimeofday(err, tv, tz));
                  exit(EXIT_FAILURE);
              }

       The above code example is available  pre-packaged  as  the  explain_settimeofday_or_die(3)
       function.

   explain_message_settimeofday
       void explain_message_settimeofday(char *message, int message_size, const struct timeval
       *tv, const struct timezone *tz);

       The explain_message_settimeofday function is used to obtain an  explanation  of  an  error
       returned  by  the  settimeofday(2)  system call. The least the message will contain is the
       value of strerror(errno), but usually it will do much better, and indicate the  underlying
       cause in more detail.

       The errno global variable will be used to obtain the error value to be decoded.

       message The  location in which to store the returned message. If a suitable message return
               buffer is supplied, this function is thread safe.

       message_size
               The size in bytes of the location in which to store the returned message.

       tv      The original tv, exactly as passed to the settimeofday(2) system call.

       tz      The original tz, exactly as passed to the settimeofday(2) system call.

       Example: This function is intended to be used  in  a  fashion  similar  to  the  following
       example:
              if (settimeofday(tv, tz) < 0)
              {
                  char message[3000];
                  explain_message_settimeofday(message, sizeof(message), tv, tz);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       The  above  code  example  is available pre-packaged as the explain_settimeofday_or_die(3)
       function.

   explain_message_errno_settimeofday
       void explain_message_errno_settimeofday(char *message, int message_size, int errnum, const
       struct timeval *tv, const struct timezone *tz);

       The  explain_message_errno_settimeofday  function  is  used to obtain an explanation of an
       error returned by the settimeofday(2) system call. The least the message will  contain  is
       the  value  of  strerror(errno),  but  usually  it  will  do much better, and indicate the
       underlying cause in more detail.

       message The location in which to store the returned message. If a suitable message  return
               buffer is supplied, this function is thread safe.

       message_size
               The size in bytes of the location in which to store the returned message.

       errnum  The  error  value  to  be decoded, usually obtained from the errno global variable
               just before this function is called. This is necessary if you  need  to  call  any
               code  between the system call to be explained and this function, because many libc
               functions will alter the value of errno.

       tv      The original tv, exactly as passed to the settimeofday(2) system call.

       tz      The original tz, exactly as passed to the settimeofday(2) system call.

       Example: This function is intended to be used  in  a  fashion  similar  to  the  following
       example:
              if (settimeofday(tv, tz) < 0)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_settimeofday(message, sizeof(message), err, tv, tz);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       The  above  code  example  is available pre-packaged as the explain_settimeofday_or_die(3)
       function.

SEE ALSO

       settimeofday(2)
               sets system time

       explain_settimeofday_or_die(3)
               sets system time and report errors

COPYRIGHT

       libexplain version 1.4
       Copyright (C) 2013 Peter Miller

                                                                          explain_settimeofday(3)