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NAME

       explain_gettimeofday - explain gettimeofday(2) errors

SYNOPSIS

       #include <libexplain/gettimeofday.h>
       const  char  *explain_gettimeofday(struct  timeval *tv, struct timezone
       *tz);
       const char *explain_errno_gettimeofday(int errnum, struct timeval  *tv,
       struct timezone *tz);
       void   explain_message_gettimeofday(char  *message,  int  message_size,
       struct timeval *tv, struct timezone *tz);
       void     explain_message_errno_gettimeofday(char     *message,      int
       message_size, int errnum, struct timeval *tv, struct timezone *tz);

DESCRIPTION

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

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

       The  explain_gettimeofday  function is used to obtain an explanation of
       an error returned by the gettimeofday(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.

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

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

       tz      The original tz,  exactly  as  passed  to  the  gettimeofday(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.

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

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

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

       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  gettimeofday(2)
               system call.

       tz      The  original  tz,  exactly  as  passed  to the gettimeofday(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.

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

       The explain_message_gettimeofday function may be  used  to   obtain  an
       explanation  of  an  error returned by the gettimeofday(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.

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

       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 gettimeofday(2)
               system call.

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

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

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

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

       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  gettimeofday(2)
               system call.

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

SEE ALSO

       gettimeofday(2)
               get time

       explain_gettimeofday_or_die(3)
               get time and report errors

COPYRIGHT

       libexplain version 0.19
       Copyright (C) 2008 Peter Miller

                                                       explain_gettimeofday(3)