explain_fcntl(3)					     Library Functions Manual						  explain_fcntl(3)

NAME

       explain_fcntl - explain fcntl(2) errors

SYNOPSIS

       #include <libexplain/fcntl.h>
       const char *explain_fcntl(int fildes, int command, long arg);
       const char *explain_errno_fcntl(int errnum, int fildes, int command, long arg);
       void explain_message_fcntl(char *message, int message_size, int fildes, int command, long arg);
       void explain_message_errno_fcntl(char *message, int message_size, int errnum, int fildes, int command, long arg);

DESCRIPTION

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

   explain_fcntl
       const char *explain_fcntl(int fildes, int command, long arg);

       The  explain_fcntl  function is used to obtain an explanation of an error returned by the fcntl(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:
	      if (fcntl(fildes, command, arg) < 0)
	      {
		  fprintf(stderr, "%s
", explain_fcntl(fildes, command, arg));
		  exit(EXIT_FAILURE);
	      }

       fildes  The original fildes, exactly as passed to the fcntl(2) system call.

       command The original command, exactly as passed to the fcntl(2) system call.

       arg     The original arg, exactly as passed to the fcntl(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 buffer across all threads, and many other functions in this library.

   explain_errno_fcntl
       const char *explain_errno_fcntl(int errnum, int fildes, int command, long arg);

       The explain_errno_fcntl function is used to obtain an explanation of an error returned by the fcntl(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:
	      if (fcntl(fildes, command, arg) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s
", explain_errno_fcntl(err, fildes, command, arg));
		  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.

       fildes  The original fildes, exactly as passed to the fcntl(2) system call.

       command The original command, exactly as passed to the fcntl(2) system call.

       arg     The original arg, exactly as passed to the fcntl(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 buffer across all threads, and many other functions in this library.

   explain_message_fcntl
       void explain_message_fcntl(char *message, int message_size, int fildes, int command, long arg);

       The  explain_message_fcntl  function may be used to  obtain an explanation of an error returned by the fcntl(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:
	      if (fcntl(fildes, command, arg) < 0)
	      {
		  char message[3000];
		  explain_message_fcntl(message, sizeof(message), fildes, command, arg);
		  fprintf(stderr, "%s
", 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 returned message.

       fildes  The original fildes, exactly as passed to the fcntl(2) system call.

       command The original command, exactly as passed to the fcntl(2) system call.

       arg     The original arg, exactly as passed to the fcntl(2) system call.

   explain_message_errno_fcntl
       void explain_message_errno_fcntl(char *message, int message_size, int errnum, int fildes, int command, long arg);

       The  explain_message_errno_fcntl function may be used to obtain an explanation of an error returned by the fcntl(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:
	      if (fcntl(fildes, command, arg) < 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_fcntl(message, sizeof(message), err, fildes,
		      command, arg);
		  fprintf(stderr, "%s
", 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 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.

       fildes  The original fildes, exactly as passed to the fcntl(2) system call.

       command The original command, exactly as passed to the fcntl(2) system call.

       arg     The original arg, exactly as passed to the fcntl(2) system call.

SEE ALSO

       fcntl(2)
	       manipulate a file descriptor

       explain_fcntl_or_die(3)
	       manipulate a file descriptor and report errors

COPYRIGHT

       libexplain version 0.52
       Copyright (C) 2008 Peter Miller

																  explain_fcntl(3)