Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
explain_setpgrp(3)	   Library Functions Manual	    explain_setpgrp(3)

NAME
       explain_setpgrp - explain setpgrp(2) errors

SYNOPSIS
       #include	<libexplain/setpgrp.h>
       const char *explain_setpgrp(pid_t pid, pid_t pgid);
       const char *explain_errno_setpgrp(int errnum, pid_t pid,	pid_t pgid);
       void explain_message_setpgrp(char *message, int message_size, pid_t
       pid, pid_t pgid);
       void explain_message_errno_setpgrp(char *message, int message_size, int
       errnum, pid_t pid, pid_t	pgid);

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

       Note: the setpgrp(2) function has two implementations.	The  System  V
       version has no arguments, while the BSD version has two arguments.  For
       simplicity of implementation, the argument list seen here includes  the
       pid and pgid arguments.

       The  System V getpgid() semantics can be	obtained by calling setpgrp(0,
       0) on systems with the BSD version, and this is the API for libexplain,
       even on systems that do not use the BSD API.

   explain_setpgrp
       const char *explain_setpgrp(pid_t pid, pid_t pgid);

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

       pid     The  original  pid,  exactly as passed to the setpgrp(2)	system
	       call.

       pgid    The original pgid, exactly as passed to the  setpgrp(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 (setpgrp(pid, pgid) < 0)
	      {
		  fprintf(stderr, "%s\n", explain_setpgrp(pid, pgid));
		  exit(EXIT_FAILURE);
	      }

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

   explain_errno_setpgrp
       const char *explain_errno_setpgrp(int errnum, pid_t pid,	pid_t pgid);

       The explain_errno_setpgrp function is used to obtain an explanation  of
       an  error returned by the setpgrp(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.

       pid     The  original  pid,  exactly as passed to the setpgrp(2)	system
	       call.

       pgid    The original pgid, exactly as passed to the  setpgrp(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 (setpgrp(pid, pgid) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_setpgrp(err, pid,
		  pgid));
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_setpgrp
       void explain_message_setpgrp(char *message, int message_size, pid_t
       pid, pid_t pgid);

       The explain_message_setpgrp function is used to obtain  an  explanation
       of  an error returned by	the setpgrp(2) system call. The	least the mes-
       sage 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.

       pid     The  original  pid,  exactly as passed to the setpgrp(2)	system
	       call.

       pgid    The original pgid, exactly as passed to the  setpgrp(2)	system
	       call.

       Example:	 This  function	is intended to be used in a fashion similar to
       the following example:
	      if (setpgrp(pid, pgid) < 0)
	      {
		  char message[3000];
		  explain_message_setpgrp(message, sizeof(message), pid,
		  pgid);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_errno_setpgrp
       void explain_message_errno_setpgrp(char *message, int message_size, int
       errnum, pid_t pid, pid_t	pgid);

       The  explain_message_errno_setpgrp function is used to obtain an	expla-
       nation of an error returned by the setpgrp(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  de-
       tail.

       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.

       pid     The original pid, exactly as passed to  the  setpgrp(2)	system
	       call.

       pgid    The  original  pgid, exactly as passed to the setpgrp(2)	system
	       call.

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

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

SEE ALSO
       setpgrp(2)
	       set process group

       explain_setpgrp_or_die(3)
	       set process group and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2011 Peter	Miller

							    explain_setpgrp(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=explain_setpgrp&sektion=3&manpath=FreeBSD+12.2-RELEASE+and+Ports>

home | help