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explain_link(3)		   Library Functions Manual	       explain_link(3)

NAME
       explain_link - explain link(2) errors

SYNOPSIS
       #include	<libexplain/link.h>
       const char *explain_link(const char *oldpath, const char	*newpath);
       const  char  *explain_errno_link(int errnum, const char *oldpath, const
       char *newpath);
       void explain_message_link(char *message,	int message_size,  const  char
       *oldpath, const char *newpath);
       void  explain_message_errno_link(char  *message,	 int message_size, int
       errnum, const char *oldpath, const char *newpath);

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

   explain_link
       const char *explain_link(const char *oldpath, const char	*newpath);

       The  explain_link function is used to obtain an explanation of an error
       returned	by the link(2) system call.  The least the message  will  con-
       tain  is	the value of strerror(errno), but usually it will do much bet-
       ter, 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 (link(oldpath,	newpath) < 0)
	      {
		  fprintf(stderr, "%s\n", explain_link(oldpath,	newpath));
		  exit(EXIT_FAILURE);
	      }

       oldpath The original oldpath, exactly as	passed to the  link(2)	system
	       call.

       newpath The  original  newpath, exactly as passed to the	link(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, in-
	       cluding 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_link
       const  char  *explain_errno_link(int errnum, const char *oldpath, const
       char *newpath);

       The explain_errno_link function is used to obtain an explanation	of  an
       error  returned by the link(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 fol-
       lowing example:
	      if (link(oldpath,	newpath) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_link(err, oldpath, newpath));
		  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.

       oldpath The original oldpath, exactly as	passed to the  link(2)	system
	       call.

       newpath The  original  newpath, exactly as passed to the	link(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, in-
	       cluding 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_link
       void  explain_message_link(char	*message, int message_size, const char
       *oldpath, const char *newpath);

       The explain_message_link	function may be	used to	 obtain	an explanation
       of an error returned by the link(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 (link(oldpath,	newpath) < 0)
	      {
		  char message[3000];
		  explain_message_link(message,	sizeof(message), oldpath, newpath);
		  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 re-
	       turned message.

       oldpath The original oldpath, exactly as	passed to the  link(2)	system
	       call.

       newpath The  original  newpath, exactly as passed to the	link(2)	system
	       call.

   explain_message_errno_link
       void explain_message_errno_link(char *message,  int  message_size,  int
       errnum, const char *oldpath, const char *newpath);

       The explain_message_errno_link function may be used to obtain an	expla-
       nation of an error returned by the link(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  fol-
       lowing example:
	      if (link(oldpath,	newpath) < 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_link(message, sizeof(message), err,
		      oldpath, newpath);
		  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 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.

       oldpath The original oldpath, exactly as	passed to the  link(2)	system
	       call.

       newpath The  original  newpath, exactly as passed to the	link(2)	system
	       call.

SEE ALSO
       link(2) make a new name for a file

       explain_link_or_die(3)
	       make a new name for a file and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2008 Peter	Miller

							       explain_link(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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