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NAME

       explain_sethostname - explain sethostname(2) errors

SYNOPSIS

       #include <libexplain/sethostname.h>
       const char *explain_sethostname(const char *name, size_t name_size);
       const  char  *explain_errno_sethostname(int  errnum,  const char *name,
       size_t name_size);
       void explain_message_sethostname(char *message, int message_size, const
       char *name, size_t name_size);
       void explain_message_errno_sethostname(char *message, int message_size,
       int errnum, const char *name, size_t name_size);

DESCRIPTION

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

   explain_sethostname
       const char *explain_sethostname(const char *name, size_t name_size);

       The explain_sethostname function is used to obtain an explanation of an
       error returned by the sethostname(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 (sethostname(name, name_size) < 0)
              {
                  fprintf(stderr, "%s\n", explain_sethostname(name, name_size));
                  exit(EXIT_FAILURE);
              }

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

       name    The  original  name,  exactly  as  passed to the sethostname(2)
               system call.

       name_size
               The original name_size, exactly as passed to the sethostname(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_sethostname
       const char *explain_errno_sethostname(int  errnum,  const  char  *name,
       size_t name_size);

       The explain_errno_sethostname function is used to obtain an explanation
       of an error returned by the sethostname(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.

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

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

       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.

       name    The  original  name,  exactly  as  passed to the sethostname(2)
               system call.

       name_size
               The original name_size, exactly as passed to the sethostname(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_sethostname
       void explain_message_sethostname(char *message, int message_size, const
       char *name, size_t name_size);

       The   explain_message_sethostname   function   is  used  to  obtain  an
       explanation of an error returned by  the  sethostname(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 (sethostname(name, name_size) < 0)
              {
                  char message[3000];
                  explain_message_sethostname(message, sizeof(message), name, name_size);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

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

       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.

       name    The  original  name,  exactly  as  passed to the sethostname(2)
               system call.

       name_size
               The original name_size, exactly as passed to the sethostname(2)
               system call.

   explain_message_errno_sethostname
       void explain_message_errno_sethostname(char *message, int message_size,
       int errnum, const char *name, size_t name_size);

       The explain_message_errno_sethostname function is  used  to  obtain  an
       explanation  of  an  error  returned by the sethostname(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.

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

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

       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.

       name    The  original  name,  exactly  as  passed to the sethostname(2)
               system call.

       name_size
               The original name_size, exactly as passed to the sethostname(2)
               system call.

SEE ALSO

       sethostname(2)
               get/set hostname

       explain_sethostname_or_die(3)
               get/set hostname and report errors

COPYRIGHT

       libexplain version 0.19
       Copyright (C) 2009 Peter Miller

                                                        explain_sethostname(3)