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explain_sethostname(3)	   Library Functions Manual	explain_sethostname(3)

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 fol-
       lowing 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   ex-
       plain_sethostname_or_die(3) function.

       name    The original name, exactly as passed to the sethostname(2) sys-
	       tem 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 buf-
       fer 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  fol-
       lowing 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  ex-
       plain_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) sys-
	       tem 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 buf-
       fer 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  explana-
       tion 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 de-
       tail.

       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 fol-
       lowing 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   ex-
       plain_sethostname_or_die(3) function.

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

       message_size
	       The  size  in  bytes  of	the location in	which to store the re-
	       turned message.

       name    The original name, exactly as passed to the sethostname(2) sys-
	       tem 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 ex-
       planation 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 fol-
       lowing 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   ex-
       plain_sethostname_or_die(3) function.

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

       message_size
	       The  size  in  bytes  of	the location in	which to store the re-
	       turned 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) sys-
	       tem 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 1.3
       Copyright (C) 2009 Peter	Miller

							explain_sethostname(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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