Content-type: text/html Man page of uswitch

uswitch

Section: System Calls (2)
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NAME

uswitch - Get or set compatibility environment specific behavior for a calling process through the uswitch value.  

SYNOPSIS

#include <sys/uswitch.h>

long uswitch( long cmd, long mask );
 

PARAMETERS

Specifies the requested actions. The valid cmd values are: Returns the current uswitch value for the calling process. If mask is non-zero, it returns the status of specific uswitch bit-mask(s). Changes the current uswitch value for the calling process as specified by the mask bit-mask(s). The following bit-masks are valid when specified with either of the values for the cmd parameter: Specifies System V NULL pointer behavior. Specifies process requests enhanced core file naming.
 

DESCRIPTION

The uswitch system call is used to get or change the compatibility environment specific behavior in Tru64 UNIX. Any changes affect the calling process and its children.

When the USW_NULLP bit of uswitch is set to 1, the System V method of treating NULL pointers is applied. In this method, references to a NULL pointer always returns zero (0). When this bit-mask is reset to zero (0), subsequent references to a NULL pointer generate a segmentation violation signal (SIGSEGV).

When the USW_CORE bit of uswitch is set to 1, the process requests enhanced core file naming. The bit-mask, when set, can be inherited when the process forks. The bit-mask is cleared when an exec system call is executed. See core(4) for more information about core files.

Any write(2) references to NULL pointers generate a segmentation violation signal (SIGSEGV) regardless of the uswitch value.
 

NOTES

Usage of this system call may make the application non-portable.
 

RETURN VALUES

Upon successful completion, either the current or new uswitch value for mask is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.
 

ERRORS

If the uswitch system call fails, the uswitch value remains unchanged and errno is set to the following: The mask is greater than USW_MAX or less than USW_MIN.
 

EXAMPLES

The following code sample sets the bit mask for System V NULL pointer behavior:

long uswitch_val;

... uswitch_val = uswitch(USC_GET,0); /* Gets current value*/ uswitch(USC_SET, uswitch_val | USW_NULLP); /* Sets USW_NULLP bit */ The following code sample sets the bit mask for enhanced core file names:

long uswitch_val;

... uswitch_val = uswitch(USC_GET,0); /* Gets current value*/ uswitch(USC_SET, uswitch_val | USW_CORE); /* Sets USW_CORE bit */


 

Index

NAME
SYNOPSIS
PARAMETERS
DESCRIPTION
NOTES
RETURN VALUES
ERRORS
EXAMPLES

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Time: 02:40:16 GMT, October 02, 2010