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explain_gethostname(3)	   Library Functions Manual	explain_gethostname(3)

NAME
       explain_gethostname - explain gethostname(2) errors

SYNOPSIS
       #include	<libexplain/gethostname.h>
       const char *explain_gethostname(char *data, size_t data_size);
       const  char  *explain_errno_gethostname(int  errnum, char *data,	size_t
       data_size);
       void explain_message_gethostname(char *message, int message_size,  char
       *data, size_t data_size);
       void explain_message_errno_gethostname(char *message, int message_size,
       int errnum, char	*data, size_t data_size);

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

   explain_gethostname
       const char *explain_gethostname(char *data, size_t data_size);

       The explain_gethostname function	is used	to obtain an explanation of an
       error returned by the gethostname(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 (gethostname(data, data_size) < 0)
	      {
		  fprintf(stderr, "%s\n", explain_gethostname(data, data_size));
		  exit(EXIT_FAILURE);
	      }

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

       data    The original data, exactly as passed to the gethostname(2) sys-
	       tem call.

       data_size
	       The original data_size, exactly as passed to the	gethostname(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_gethostname
       const char *explain_errno_gethostname(int errnum,  char	*data,	size_t
       data_size);

       The explain_errno_gethostname function is used to obtain	an explanation
       of an error returned by the gethostname(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 (gethostname(data, data_size) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_gethostname(err, data, data_size));
		  exit(EXIT_FAILURE);
	      }

       The  above  code	example	is available pre-packaged as the explain_geth-
       ostname_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.

       data    The original data, exactly as passed to the gethostname(2) sys-
	       tem call.

       data_size
	       The original data_size, exactly as passed to the	gethostname(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_gethostname
       void  explain_message_gethostname(char *message,	int message_size, char
       *data, size_t data_size);

       The explain_message_gethostname function	is used	to obtain an  explana-
       tion of an error	returned by the	gethostname(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 (gethostname(data, data_size) < 0)
	      {
		  char message[3000];
		  explain_message_gethostname(message, sizeof(message),	data, data_size);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

       The above code example is available pre-packaged	as  the	 explain_geth-
       ostname_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
	       returned	message.

       data    The original data, exactly as passed to the gethostname(2) sys-
	       tem call.

       data_size
	       The original data_size, exactly as passed to the	gethostname(2)
	       system call.

   explain_message_errno_gethostname
       void explain_message_errno_gethostname(char *message, int message_size,
       int errnum, char	*data, size_t data_size);

       The  explain_message_errno_gethostname  function	 is  used to obtain an
       explanation of an error returned	by  the	 gethostname(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 (gethostname(data, data_size) < 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_gethostname(message, sizeof(message), err, data,
		      data_size);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

       The above code example is available pre-packaged	as  the	 explain_geth-
       ostname_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
	       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.

       data    The original data, exactly as passed to the gethostname(2) sys-
	       tem call.

       data_size
	       The original data_size, exactly as passed to the	gethostname(2)
	       system call.

SEE ALSO
       gethostname(2)
	       get/set hostname

       explain_gethostname_or_die(3)
	       get/set hostname	and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2009 Peter	Miller

							explain_gethostname(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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