/*

 * 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 (c) 2010, Oracle and/or it's affiliates.  All rights reserved.

 */

/*

 * This compiles to a module that can be preloaded during a build.  If this

 * is preloaded, it interposes on time(2), gettimeofday(3C), and

 * clock_gethrtime(3C) and returns a constant number of seconds since epoch

 * when the execname matches one of the desired "programs" and TIME_CONSTANT

 * contains an integer value to be returned.

 */

#include <stdlib.h>

#include <ucontext.h>

#include <dlfcn.h>

#include <strings.h>

#include <time.h>

/* The list of programs that we want to use a constant time. */

static char *programs[] = { "autogen", "bash", "cpp", "cc1", "date", "doxygen",

	"erl", "javadoc", "ksh", "ksh93", "ld", "perl", "perl5.8.4", "perl5.10",

	"ruby", "sh", NULL };

static int

stack_info(uintptr_t pc, int signo, void *arg)

{

	Dl_info info;

	void *sym;

	if (dladdr1((void *)pc, &info, &sym, RTLD_DL_SYMENT) != NULL) {

		if (strstr(info.dli_fname, ".so") == NULL)

			*(char **)arg = (char *)info.dli_fname;

	}

	return (0);

}

static char *

my_execname()

{

	static char *execname;

	if (execname == NULL) {

		ucontext_t ctx;

		if (getcontext(&ctx) == 0)

			walkcontext(&ctx, stack_info, &execname);

		if (execname != NULL) {

			char *s = strrchr(execname, '/');

			if (s != NULL)

				execname = ++s;

		}

	}

	return (execname);

}

static time_t

time_constant()

{

	char *execname = my_execname();

	time_t result = -1;

	if (execname != NULL) {

		int i;

		for (i = 0; programs[i] != NULL; i++)

			if (strcmp(execname, programs[i]) == 0) {

				static char *time_string;

				if (time_string == NULL)

					time_string = getenv("TIME_CONSTANT");

				if (time_string != NULL)

					result = atoll(time_string);

				break;

			}

	}

	return (result);

}

time_t

time(time_t *ptr)

{

	time_t result = time_constant();

	if (result == (time_t)-1) {

		static time_t (*fptr)(time_t *);

		if (fptr == NULL)

			fptr = (time_t (*)(time_t *))dlsym(RTLD_NEXT, "time");

		result = (fptr)(ptr);

	} else if (ptr != NULL)

			*ptr = result;

	return (result);

}

int

gettimeofday(struct timeval *tp, void *tzp)

{

	static int (*fptr)(struct timeval *, void *);

	int result = -1;

	if (fptr == NULL)

		fptr = (int (*)(struct timeval *, void *))dlsym(RTLD_NEXT,

				"gettimeofday");

	if ((result = (fptr)(tp, tzp)) == 0) {

		time_t curtime = time_constant();

		if (curtime != (time_t)-1)

			tp->tv_sec = curtime;

	}

	return (result);

}

int

clock_gettime(clockid_t clock_id, struct timespec *tp)

{

	static int (*fptr)(clockid_t, struct timespec *);

	int result = -1;

	if (fptr == NULL)

		fptr = (int (*)(clockid_t, struct timespec *))dlsym(RTLD_NEXT,

				"clock_gettime");

	if ((result = (fptr)(clock_id, tp)) == 0) {

		time_t curtime = time_constant();

		if (curtime != (time_t)-1)

			tp->tv_sec = curtime;

	}

	return (result);

}