/*

 * CDDL HEADER START

 *

 * The contents of this file are subject to the terms of the

 * Common Development and Distribution License (the "License").

 * You may not use this file except in compliance with the License.

 *

 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE

 * or http://www.opensolaris.org/os/licensing.

 * See the License for the specific language governing permissions

 * and limitations under the License.

 *

 * When distributing Covered Code, include this CDDL HEADER in each

 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.

 * If applicable, add the following below this CDDL HEADER, with the

 * fields enclosed by brackets "[]" replaced with your own identifying

 * information: Portions Copyright [yyyy] [name of copyright owner]

 *

 * CDDL HEADER END

 */

/*

 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.

 * Use is subject to license terms.

 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

#include <assert.h>

#include <errno.h>

#include <fcntl.h>

#include <stdarg.h>

#include <stdio.h>

#include <stdlib.h>

#include <strings.h>

#include <thread.h>

#include <unistd.h>

#include <sys/modctl.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <sys/lx_brand.h>

#include <sys/lx_debug.h>

#include <sys/lx_misc.h>

/* internal debugging state */

static char	*lx_debug_path = NULL;		/* debug output file path */

static char	lx_debug_path_buf[MAXPATHLEN];

void

lx_debug_enable(void)

{

	/* send all debugging output to /dev/tty */

	lx_debug_path = "/dev/tty";

	lx_debug("lx_debug: debugging output enabled: %s", lx_debug_path);

}

void

lx_debug_init(void)

{

	if (getenv("LX_DEBUG") == NULL)

		return;

	/*

	 * It's OK to use this value without any locking, as all callers can

	 * use the return value to decide whether extra work should be done

	 * before calling lx_debug().

	 *

	 * If debugging is disabled after a routine calls this function it

	 * doesn't really matter as lx_debug() will see debugging is disabled

	 * and will not output anything.

	 */

	lx_debug_enabled = 1;

	/* check if there's a debug log file specified */

	lx_debug_path = getenv("LX_DEBUG_FILE");

	if (lx_debug_path == NULL) {

		/* send all debugging output to /dev/tty */

		lx_debug_path = "/dev/tty";

	}

	(void) strlcpy(lx_debug_path_buf, lx_debug_path,

	    sizeof (lx_debug_path_buf));

	lx_debug_path = lx_debug_path_buf;

	lx_debug("lx_debug: debugging output ENABLED to path: \"%s\"",

	    lx_debug_path);

}

void

lx_debug(const char *msg, ...)

{

	va_list		ap;

	char		buf[LX_MSG_MAXLEN + 1];

	int		rv, fd, n;

	int		errno_backup;

	if (lx_debug_enabled == 0)

		return;

	errno_backup = errno;

	/* prefix the message with pid/tid */

	if ((n = snprintf(buf, sizeof (buf), "%u/%u: ",

	    getpid(), thr_self())) == -1) {

		errno = errno_backup;

		return;

	}

	/* format the message */

	va_start(ap, msg);

	rv = vsnprintf(&buf[n], sizeof (buf) - n, msg, ap);

	va_end(ap);

	if (rv == -1) {

		errno = errno_backup;

		return;

	}

	/* add a carrige return if there isn't one already */

	if ((buf[strlen(buf) - 1] != '\n') &&

	    (strlcat(buf, "\n", sizeof (buf)) >= sizeof (buf))) {

		errno = errno_backup;

		return;

	}

	/*

	 * Open the debugging output file.  note that we don't protect

	 * ourselves against exec or fork1 here.  if an mt process were

	 * to exec/fork1 while we're doing this they'd end up with an

	 * extra open desciptor in their fd space.  a'well.  shouldn't

	 * really matter.

	 */

	if ((fd = open(lx_debug_path,

	    O_WRONLY|O_APPEND|O_CREAT|O_NDELAY|O_NOCTTY, 0666)) == -1) {

		return;

	}

	(void) fchmod(fd, 0666);

	/* we retry in case of EINTR */

	do {

		rv = write(fd, buf, strlen(buf));

	} while ((rv == -1) && (errno == EINTR));

	(void) fsync(fd);

	(void) close(fd);

	errno = errno_backup;

}