/* 
   Unix SMB/CIFS implementation.
   Samba system utilities
   Copyright (C) Andrew Tridgell 1992-1998
   Copyright (C) Jeremy Allison 1998-2002
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"

/*
   The idea is that this file will eventually have wrappers around all
   important system calls in samba. The aims are:

   - to enable easier porting by putting OS dependent stuff in here

   - to allow for hooks into other "pseudo-filesystems"

   - to allow easier integration of things like the japanese extensions

   - to support the philosophy of Samba to expose the features of
     the OS within the SMB model. In general whatever file/printer/variable
     expansions/etc make sense to the OS should be acceptable to Samba.
*/



/*******************************************************************
 A wrapper for usleep in case we don't have one.
********************************************************************/

int sys_usleep(long usecs)
{
#ifndef HAVE_USLEEP
	struct timeval tval;
#endif

	/*
	 * We need this braindamage as the glibc usleep
	 * is not SPEC1170 complient... grumble... JRA.
	 */

	if(usecs < 0 || usecs > 1000000) {
		errno = EINVAL;
		return -1;
	}

#if HAVE_USLEEP
	usleep(usecs);
	return 0;
#else /* HAVE_USLEEP */
	/*
	 * Fake it with select...
	 */
	tval.tv_sec = 0;
	tval.tv_usec = usecs/1000;
	select(0,NULL,NULL,NULL,&tval);
	return 0;
#endif /* HAVE_USLEEP */
}

/**************************************************************************
 Wrapper for random().
****************************************************************************/

long sys_random(void)
{
#if defined(HAVE_RANDOM)
	return (long)random();
#elif defined(HAVE_RAND)
	return (long)rand();
#else
	DEBUG(0,("Error - no random function available !\n"));
	exit(1);
#endif
}

/**************************************************************************
 Wrapper for srandom().
****************************************************************************/

void sys_srandom(unsigned int seed)
{
#if defined(HAVE_SRANDOM)
	srandom(seed);
#elif defined(HAVE_SRAND)
	srand(seed);
#else
	DEBUG(0,("Error - no srandom function available !\n"));
	exit(1);
#endif
}

/**************************************************************************
 Wrapper for fork. Ensures that mypid is reset. Used so we can write
 a sys_getpid() that only does a system call *once*.
****************************************************************************/

static pid_t mypid = (pid_t)-1;

pid_t sys_fork(void)
{
	pid_t forkret = fork();

	if (forkret == (pid_t)0) /* Child - reset mypid so sys_getpid does a system call. */
		mypid = (pid_t) -1;

	return forkret;
}

/**************************************************************************
 Wrapper for getpid. Ensures we only do a system call *once*.
****************************************************************************/

pid_t sys_getpid(void)
{
	if (mypid == (pid_t)-1)
		mypid = getpid();

	return mypid;
}

/****************************************************************************
Check if we are setuid root.  Used in libsmb and smbpasswd paranoia checks.
****************************************************************************/
BOOL is_setuid_root(void) 
{
	return (geteuid() == (uid_t)0) && (getuid() != (uid_t)0);
}

/*******************************************************************
 Similar to select() but catch EINTR and continue.
********************************************************************/

int sys_select_intr(int maxfd, fd_set *readfds, fd_set *writefds, fd_set *errorfds, struct timeval *tval)
{
	int ret;
	fd_set *readfds2, readfds_buf, *writefds2, writefds_buf, *errorfds2, errorfds_buf;

	readfds2 = (readfds ? &readfds_buf : NULL);
	writefds2 = (writefds ? &writefds_buf : NULL);
	errorfds2 = (errorfds ? &errorfds_buf : NULL);

	do {
		if (readfds)
			readfds_buf = *readfds;
		if (writefds)
			writefds_buf = *writefds;
		if (errorfds)
			errorfds_buf = *errorfds;
		ret = select(maxfd, readfds2, writefds2, errorfds2, tval);
	} while (ret == -1 && errno == EINTR);

	if (readfds)
		*readfds = readfds_buf;
	if (writefds)
		*writefds = writefds_buf;
	if (errorfds)
		*errorfds = errorfds_buf;

	return ret;
}

/**************************************************************************
A wrapper for gethostbyname() that tries avoids looking up hostnames 
in the root domain, which can cause dial-on-demand links to come up for no
apparent reason.
****************************************************************************/

struct hostent *sys_gethostbyname(const char *name)
{
#ifdef REDUCE_ROOT_DNS_LOOKUPS
	char query[256], hostname[256];
	char *domain;

	/* Does this name have any dots in it? If so, make no change */

	if (strchr(name, '.'))
		return(gethostbyname(name));

	/* Get my hostname, which should have domain name 
		attached. If not, just do the gethostname on the
		original string. 
	*/

	gethostname(hostname, sizeof(hostname) - 1);
	hostname[sizeof(hostname) - 1] = 0;
	if ((domain = strchr(hostname, '.')) == NULL)
		return(gethostbyname(name));

	/* Attach domain name to query and do modified query.
		If names too large, just do gethostname on the
		original string.
	*/

	if((strlen(name) + strlen(domain)) >= sizeof(query))
		return(gethostbyname(name));

	slprintf(query, sizeof(query)-1, "%s%s", name, domain);
	return(gethostbyname(query));
#else /* REDUCE_ROOT_DNS_LOOKUPS */
	return(gethostbyname(name));
#endif /* REDUCE_ROOT_DNS_LOOKUPS */
}

/*******************************************************************
 An open() wrapper that will deal with 64 bit filesizes.
********************************************************************/

int sys_open(const char *path, int oflag, mode_t mode)
{
#if defined(HAVE_EXPLICIT_LARGEFILE_SUPPORT) && defined(HAVE_OPEN64)
	return open64(path, oflag, mode);
#else
	return open(path, oflag, mode);
#endif
}