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
       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 following 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, including other
	       threads.

       Note: This function is not thread safe, because it shares a return buffer 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 following 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 neces-
	       sary 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,  including  other
	       threads.

       Note: This function is not thread safe, because it shares a return buffer 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 following 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 returned 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 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 following 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 returned message.

       errnum  The error value to be decoded, usually obtained from the errno global variable just before this function is called.  This is neces-
	       sary 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 0.52
       Copyright (C) 2008 Peter Miller

AUTHOR

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

																   explain_open(3)