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explain_shmctl(3)	   Library Functions Manual	     explain_shmctl(3)

NAME
       explain_shmctl -	explain	shmctl(2) errors

SYNOPSIS
       #include	<libexplain/shmctl.h>
       const char *explain_shmctl(int shmid, int command, struct shmid_ds
       *data);
       const char *explain_errno_shmctl(int errnum, int	shmid, int command,
       struct shmid_ds *data);
       void explain_message_shmctl(char	*message, int message_size, int	shmid,
       int command, struct shmid_ds *data);
       void explain_message_errno_shmctl(char *message,	int message_size, int
       errnum, int shmid, int command, struct shmid_ds *data);

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

   explain_shmctl
       const char *explain_shmctl(int shmid, int command, struct shmid_ds
       *data);

       The  explain_shmctl function is used to obtain an explanation of	an er-
       ror returned by the shmctl(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.

       shmid   The  original  shmid, exactly as	passed to the shmctl(2)	system
	       call.

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

       data    The  original  data,  exactly as	passed to the shmctl(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 buf-
       fer across all threads, and many	other functions	in this	library.

       Example:	 This  function	is intended to be used in a fashion similar to
       the following example:
	      if (shmctl(shmid,	command, data) < 0)
	      {
		  fprintf(stderr, "%s\n", explain_shmctl(shmid,	command,
		  data));
		  exit(EXIT_FAILURE);
	      }

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

   explain_errno_shmctl
       const char *explain_errno_shmctl(int errnum, int	shmid, int command,
       struct shmid_ds *data);

       The  explain_errno_shmctl  function is used to obtain an	explanation of
       an error	returned by the	shmctl(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.

       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.

       shmid   The original shmid, exactly as passed to	the  shmctl(2)	system
	       call.

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

       data    The original data, exactly as passed to	the  shmctl(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 buf-
       fer across all threads, and many	other functions	in this	library.

       Example:	This function is intended to be	used in	a fashion  similar  to
       the following example:
	      if (shmctl(shmid,	command, data) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_shmctl(err, shmid,
		  command, data));
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_shmctl
       void explain_message_shmctl(char	*message, int message_size, int	shmid,
       int command, struct shmid_ds *data);

       The explain_message_shmctl function is used to obtain an	explanation of
       an  error  returned by the shmctl(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.

       message The location in which to	store the returned message. If a suit-
	       able 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.

       shmid   The  original  shmid, exactly as	passed to the shmctl(2)	system
	       call.

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

       data    The  original  data,  exactly as	passed to the shmctl(2)	system
	       call.

       Example:	This function is intended to be	used in	a fashion  similar  to
       the following example:
	      if (shmctl(shmid,	command, data) < 0)
	      {
		  char message[3000];
		  explain_message_shmctl(message, sizeof(message), shmid, com-
		  mand,	data);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_errno_shmctl
       void explain_message_errno_shmctl(char *message,	int message_size, int
       errnum, int shmid, int command, struct shmid_ds *data);

       The explain_message_errno_shmctl	function is used to obtain an explana-
       tion  of	 an error returned by the shmctl(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.

       message The location in which to	store the returned message. If a suit-
	       able 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.

       shmid   The original shmid, exactly as passed to	the  shmctl(2)	system
	       call.

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

       data    The original data, exactly as passed to	the  shmctl(2)	system
	       call.

       Example:	 This  function	is intended to be used in a fashion similar to
       the following example:
	      if (shmctl(shmid,	command, data) < 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_shmctl(message,	sizeof(message), err,
		  shmid, command, data);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

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

SEE ALSO
       shmctl(2)
	       shared memory control

       explain_shmctl_or_die(3)
	       shared memory control and report	errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2011 Peter	Miller

							     explain_shmctl(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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