errstr(2) [plan9 man page]

ERRSTR(2)							System Calls Manual							 ERRSTR(2)

NAME

       errstr, werrstr - description of last system call error

SYNOPSIS

       #include <u.h>
       #include <libc.h>

       int errstr(char *err)

       void werrstr(char *fmt, ...)

DESCRIPTION

       When  a	system	call  fails it returns -1 and records a string describing the error in a per-process buffer.  Errstr swaps the contents of
       that buffer with the contents of the array err.	Err should contain at least ERRLEN characters (defined in <libc.h>).  Usually errstr  will
       be  called  with an empty string, but the exchange property provides a mechanism for libraries to set the return value for the next call to
       errstr.

       If no system call has generated an error since the last call to errstr with an empty string, the result is an empty string.

       The verb r in print(2) calls errstr and outputs the error string.

       Werrstr takes a print style format as its argument and uses it to format a string to pass to errstr.  The string returned  from	errstr	is
       discarded.

SOURCE

       /sys/src/libc/9syscall
       /sys/src/libc/9sys/werrstr.c

DIAGNOSTICS

       Errstr always returns 0.

SEE ALSO

       intro(2), perror(2)

																	 ERRSTR(2)

Razor2::Errorhandler(3pm)				User Contributed Perl Documentation				 Razor2::Errorhandler(3pm)

NAME

       Razor::Errorhandler - Error handling mechanism for Razor.

SYNOPSIS

	   package Foo;

	   use Razor::Errorhandler;
	   @ISA = qw(Razor::Errorhandler);

	   sub alive {
	       ..
	       ..
	       return
	       $self->error ("Awake, awake! Ring the alarum bell. 
			      Murther and treason!", $dagger)
		   if $self->murdered($king);
	   }

	   package main;

	   use Foo;
	   my $foo = new Foo;
	   $foo->alive($king) or print $foo->errstr();
	   # prints "Awake, awake! ... "

DESCRIPTION

       Razor::Errorhandler encapsulates the error handling mechanism used by the modules in Razor bundle. Razor::Errorhandler doesn't have a
       constructor and is meant to be inherited. The derived modules use its two methods, error() and errstr(), to communicate error messages to
       the caller.

       When a method of the derived module fails, it calls $self->error() and returns  to the caller. The error message passed to error() is made
       available to the caller through the errstr() accessor. error() also accepts a list of sensitive data that it wipes out (undef'es) before
       returning.

       The caller should never call errstr() to check for errors. errstr() should be called only when a method indicates (usually through an undef
       return value) that an error has occured. This is because errstr() is never overwritten and will always contain a value after the occurance
       of first error.

METHODS

       error($mesage, ($wipeme, $wipemetoo))
	   The first argument to error() is $message which is placed in $self->{errstr} and the remaining arguments are interpretted as variables
	   containing sensitive data that are wiped out from the memory. error() always returns undef.

       errstr()
	   errstr() is an accessor method for $self->{errstr}.

AUTHOR

       Vipul Ved Prakash, <mail@vipul.net>

SEE ALSO

       Razor::Client(3)

perl v5.14.2							    2005-08-03						 Razor2::Errorhandler(3pm)