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explain_pipe(3)		   Library Functions Manual	       explain_pipe(3)

NAME
       explain_pipe - explain pipe(2) errors

SYNOPSIS
       #include	<libexplain/pipe.h>
       const char *explain_pipe(int *pipefd);
       const char *explain_errno_pipe(int errnum, int *pipefd);
       void   explain_message_pipe(char	  *message,   int   message_size,  int
       *pipefd);
       void explain_message_errno_pipe(char *message,  int  message_size,  int
       errnum, int *pipefd);

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

   explain_pipe
       const char *explain_pipe(int *pipefd);

       The explain_pipe	function is used to obtain an explanation of an	 error
       returned	 by  the pipe(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 (pipe(pipefd) < 0)
	      {
		  fprintf(stderr, "%s\n", explain_pipe(pipefd));
		  exit(EXIT_FAILURE);
	      }

       The   above   code   example  is	 available  pre-packaged  as  the  ex-
       plain_pipe_or_die(3) function.

       pipefd  The original pipefd, exactly as passed to  the  pipe(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_pipe
       const char *explain_errno_pipe(int errnum, int *pipefd);

       The explain_errno_pipe function is used to obtain an explanation	of  an
       error  returned by the pipe(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 (pipe(pipefd) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_pipe(err, pipefd));
		  exit(EXIT_FAILURE);
	      }

       The  above  code	 example  is  available	 pre-packaged	as   the   ex-
       plain_pipe_or_die(3) function.

       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.

       pipefd  The  original  pipefd,  exactly as passed to the	pipe(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_pipe
       void   explain_message_pipe(char	  *message,   int   message_size,  int
       *pipefd);

       The explain_message_pipe	function may be	used to	 obtain	an explanation
       of an error returned by the pipe(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 (pipe(pipefd) < 0)
	      {
		  char message[3000];
		  explain_message_pipe(message,	sizeof(message), pipefd);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

       The   above   code   example  is	 available  pre-packaged  as  the  ex-
       plain_pipe_or_die(3) function.

       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.

       pipefd  The  original  pipefd,  exactly as passed to the	pipe(2)	system
	       call.

   explain_message_errno_pipe
       void explain_message_errno_pipe(char *message,  int  message_size,  int
       errnum, int *pipefd);

       The explain_message_errno_pipe function may be used to obtain an	expla-
       nation of an error returned by the pipe(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 (pipe(pipefd) < 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_pipe(message, sizeof(message), err, pipefd);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

       The   above   code   example  is	 available  pre-packaged  as  the  ex-
       plain_pipe_or_die(3) function.

       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.

       pipefd  The  original  pipefd,  exactly as passed to the	pipe(2)	system
	       call.

SEE ALSO
       pipe(2) create pipe

       explain_pipe_or_die(3)
	       create pipe and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2009 Peter	Miller

							       explain_pipe(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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