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explain_open(3)		   Library Functions Manual	       explain_open(3)

NAME
       explain_open - explain open(2) errors

SYNOPSIS
       #include	<libexplain/open.h>
       const char *explain_open(const char *pathname, int flags, int mode);
       const  char  *explain_errno_open(int  errnum, const char	*pathname, int
       flags, int mode);
       void explain_message_open(char *message,	int message_size,  const  char
       *pathname, int flags, int mode);
       void  explain_message_errno_open(char  *message,	 int message_size, int
       errnum, const char *pathname, int flags,	int mode);

DESCRIPTION
       These functions may be used to obtains explanations for open(2) errors.

   explain_open(const char *pathname, int flags, int mode);
       const char *explain_open(const char *pathname, int flags, int mode);

       The explain_open	function is used to obtain an explanation of an	 error
       returned	 by  the open(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:
	      int fd = open(pathname, flags, mode);
	      if (fd < 0)
	      {
		  fprintf(stderr, '%s0,	explain_open(pathname, flags, mode));
		  exit(EXIT_FAILURE);
	      }

       pathname
	       The  original pathname, exactly as passed to the	open(2)	system
	       call.

       flags   The original flags, exactly as passed  to  the  open(2)	system
	       call.

       mode    The original mode, exactly as passed to the open(2) system call
	       (or zero	if the original	call didn't need a mode	argument).

       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_open
       const  char  *explain_errno_open(int  errnum, const char	*pathname, int
       flags, int mode);

       The explain_errno_open function is used to obtain an explanation	of  an
       error  returned by the open(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:
	      int fd = open(pathname, flags, mode);
	      if (fd < 0)
	      {
		  int err = errno;
		  fprintf(stderr, '%s0,	explain_errno_open(err,	pathname,
		      flags, mode));
		  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.

       pathname
	       The original pathname, exactly as passed	to the open(2)	system
	       call.

       flags   The  original  flags,  exactly  as passed to the	open(2)	system
	       call.

       mode    The original mode, exactly as passed to the open(2) system call
	       (or zero	if the original	call didn't need a mode	argument).

       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_open
       void explain_message_open(char *message,	int message_size,  const  char
       *pathname, int flags, int mode);

       The  explain_message_open  function is used to obtain an	explanation of
       an error	returned by the	open(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:
	      int fd = open(pathname, flags, mode);
	      if (fd < 0)
	      {
		  char message[3000];
		  explain_message_open(message,	sizeof(message), pathname, flags,
		      mode);
		  fprintf(stderr, '%s0,	message);
		  exit(EXIT_FAILURE);
	      }

       message The location in which to	store the returned message.  Because a
	       message	return	buffer	has  been  supplied,  this function is
	       thread safe.

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

       pathname
	       The  original pathname, exactly as passed to the	open(2)	system
	       call.

       flags   The original flags, exactly as passed  to  the  open(2)	system
	       call.

       mode    The original mode, exactly as passed to the open(2) system call
	       (or zero	if the original	call didn't need a mode	argument).

   explain_message_errno_open
       void explain_message_errno_open(char *message,  int  message_size,  int
       errnum, const char *pathname, int flags,	int mode);

       The  explain_message_errno_open	function is used to obtain an explana-
       tion of an error	returned by the	open(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 exameple:
	      int fd = open(pathname, flags, mode);
	      if (fd < 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_open(message, sizeof(message), err, pathname,
		      flags, mode);
		  fprintf(stderr, '%s0,	message);
		  exit(EXIT_FAILURE);
	      }

       message The location in which to	store the returned message.  Because a
	       message return buffer  has  been	 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.

       pathname
	       The original pathname, exactly as passed	to the open(2)	system
	       call.

       flags   The  original  flags,  exactly  as passed to the	open(2)	system
	       call.

       mode    The original mode, exactly as passed to the open(2) system call
	       (or zero	if the original	call didn't need a mode	argument).

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2008 Peter	Miller

AUTHOR
       Written by Peter	Miller <pmiller@opensource.org.au>

							       explain_open(3)

NAME | SYNOPSIS | DESCRIPTION | COPYRIGHT | AUTHOR

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