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explain_fopen(3)	   Library Functions Manual	      explain_fopen(3)

NAME
       explain_fopen - explain fopen(3)	errors

SYNOPSIS
       #include	<libexplain/fopen.h>
       const char *explain_fopen(const char *path, const char *mode);
       const  char  *explain_errno_fopen(int  errnum,  const char *path, const
       char *mode);
       void explain_message_fopen(char *message, int message_size, const  char
       *path, const char *mode);
       void  explain_message_errno_fopen(char  *message, int message_size, int
       errnum, const char *path, const char *mode);

DESCRIPTION
       These functions may be used to obtain explanations for fopen(3) errors.

   explain_fopen
       const char *explain_fopen(const char *path, const char *mode);

       The explain_fopen function is used to obtain an explanation of an error
       returned	 by the	fopen(3) 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:
	      FILE *fp = fopen(path, mode);
	      if (!fp)
	      {
		  const	char *message =	explain_fopen(path, mode);
		  fprintf(stderr, '%s0,	message);
		  exit(EXIT_FAILURE);
	      }

       path    The  original  path,  exactly  as passed	to the fopen(3)	system
	       call.

       mode    The original mode, exactly as passed  to	 the  fopen(3)	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_fopen
       const char *explain_errno_fopen(int errnum,  const  char	 *path,	 const
       char *mode);

       The explain_errno_fopen function	is used	to obtain an explanation of an
       error returned by the fopen(3) 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:
	      FILE *fp = fopen(path, mode);
	      if (!fp)
	      {
		  const	char *message =	explain_errno_fopen(err, path, mode);
		  fprintf(stderr, '%s0,	message);
		  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.

       path    The  original  path,  exactly  as passed	to the fopen(3)	system
	       call.

       mode    The original mode, exactly as passed  to	 the  fopen(3)	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_fopen
       void explain_message_fopen(char *message, int message_size, const  char
       *path, const char *mode);

       The  explain_message_fopen function is used to obtain an	explanation of
       an error	returned by the	fopen(3) 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:
	      FILE *fp = fopen(path, mode);
	      if (!fp)
	      {
		  char message[3000];
		  explain_message_fopen(message, sizeof(message), path,	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.

       path    The  original  path,  exactly  as passed	to the fopen(3)	system
	       call.

       mode    The original mode, exactly as passed  to	 the  fopen(3)	system
	       call

   explain_message_errno_fopen
       void  explain_message_errno_fopen(char  *message, int message_size, int
       errnum, const char *path, const char *mode);

       The explain_message_errno_fopen function	is used	to obtain an  explana-
       tion  of	 an error returned by the fopen(3) 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:
	      FILE *fp = fopen(path, mode);
	      if (!fp)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_fopen(message, sizeof(message),	err, path,
		      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.

       path    The  original  path,  exactly  as passed	to the fopen(3)	system
	       call.

       mode    The original mode, exactly as passed  to	 the  fopen(3)	system
	       call.

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2008 Peter	Miller

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

							      explain_fopen(3)

NAME | SYNOPSIS | DESCRIPTION | COPYRIGHT | AUTHOR

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