---
name: "tst_sig"
section: "3"
platform: "linux"
package: "ltp-dev"
version: "20091231+dfsg-1"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/tst_sig"
---

# tst\_sig(3)

set up for unexpected signals

## NAME

tst\_sig - set up for unexpected signals

## SYNOPSIS

```
#include "test.h"
void tst_sig(fork_flag, handler, cleanup)
char *fork_flag;
int (*handler)();
void (*cleanup)();
```

## DESCRIPTION

*Tst\_sig* is used by UNICOS test case programs to set up signal handling functions for unexpected signals.  This provides test cases with a graceful means of exiting following an unexpected interruption by a signal. *Tst\_sig* should be called only once by a test program.

The *fork\_flag* parameter is used to tell *tst\_sig* whether or not to ignore the SIGCLD signal caused by the death of a child process that had previously been created by the [*fork*(2)](/fork/2.md) system call (see [*signal*(2)](/signal/2.md) for more information on the SIGCLD signal).

Setting *fork\_flag* to FORK will cause *tst\_sig* to ignore the SIGCLD signal.  This option should be set if the test program directly (eg. call [*fork*(2)](/fork/2.md)) or indirectly (eg. call *system*(3S)) creates a child process.

Setting *fork\_flag* to NOFORK will cause *tst\_sig* to treat the SIGCLD signal just as any other unexpected signal (ie. the *handler* will be called). This option should be set by any test program which does not directly or indirectly create any child processes.

The *handler* parameter is a pointer to a function returning type int which is executed upon the receipt of an unexpected signal. The test program may pass a pointer to a signal handling function or it may elect to use a *default handler* supplied by *tst\_sig*.

The *default handler* is specified by passing DEF\_HANDLER as the *handler* argument.  Upon receipt of an unexpected signal, the *default handler* will generate [*tst\_res*(3)](/tst_res/3.md) messages for all test results that had not been completed at the time of the signal, execute the  *cleanup* routine, if provided, and call *tst\_exit*. Note: if the *default handler* is used, the variables **TCID** and **Tst\_count** must be defined and available to *tst\_sig* (see [*tst\_res*(3)](/tst_res/3.md)).

The *cleanup* parameter is a pointer to a user-defined function returning type void which is executed by the *default handler*.  The *cleanup* function should remove any files, directories, processes, etc. created by the test program. If no cleanup is required, this parameter should be set to NULL.

## EXAMPLES

```
#include "test.h"
/*
 * the TCID and TST_TOTAL variables must be available to tst_sig
 * if the default handler is used.  The default handler will call
 * tst_res(3) and will need this information.
 */
int TCID = "tsttcs01";  /* set test case identifier */
int TST_TOTAL = 5;        /* set total number of test results */
	void tst_sig();
	/*
	 * set up for unexpected signals:
	 *		no fork() system calls will be executed during the test run
	 *		use the default signal handler provided by tst_sig
	 *		no cleanup is necessary
	 */
	tst_sig(NOFORK, DEF_HANDLER, NULL);
	void tst_sig(), cleanup();
	int handler();
	/*
	 * set up for unexpected signals:
	 *		fork() system calls will be executed during the test run
	 *		use user-defined signal handler
	 *		use cleanup
	 */
	tst_sig(FORK, handler, cleanup);
```

## SEE ALSO

[signal(2)](/signal/2.md), [tst\_res(3)](/tst_res/3.md), tst\_setup(1).

## DIAGNOSTICS

*Tst\_sig* will output warnings in standard *tst\_res* format if it cannot set up the signal handlers.