/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (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) 1984, 1986, 1987, 1988, 1989 AT&T */
/*        All Rights Reserved   */
/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include "uucp.h"

#include <unistd.h>
/* #include <sys/types.h> */
/* #include <sys/stat.h> */

static struct stat _st_buf;
static char lockname[BUFSIZ];

static void     stlock(char *);
static int      onelock(char *, char *, char *);

/*
 * make a lock file with given 'name'
 * If one already exists, send a signal 0 to the process--if
 * it fails, then unlink it and make a new one.
 *
 * input:
 *      name - name of the lock file to make
 *
 * return:
 *      0       -> success
 *      FAIL    -> failure
 */

GLOBAL int
mklock(char *name)
{
        static  char pid[SIZEOFPID+2] = { '\0' }; /* +2 for '\n' and NULL */
        static char tempfile[MAXNAMESIZE];

#ifdef V8
        char *cp;
#endif

        if (pid[0] == '\0') {
                (void) sprintf(pid, "%*ld\n", SIZEOFPID, (long)getpid());
                (void) sprintf(tempfile, "%s/LTMP.%ld", X_LOCKDIR,
                    (long)getpid());
        }

#ifdef V8       /* this wouldn't be a problem if we used lock directories */
                /* some day the truncation of system names will bite us */
        cp = rindex(name, '/');
        if (cp++ != CNULL)
                if (strlen(cp) > MAXBASENAME)
                        *(cp+MAXBASENAME) = NULLCHAR;
#endif /* V8 */
        if (onelock(pid, tempfile, name) == -1) {
                (void) unlink(tempfile);
                if (cklock(name)) {
                        return (FAIL);
                } else {
                        if (onelock(pid, tempfile, name)) {
                                (void) unlink(tempfile);
                                DEBUG(4, "ulockf failed in onelock()\n%s", "");
                                return (FAIL);
                        }
                }
        }

        stlock(name);
        return (0);
}

/*
 * check to see if the lock file exists and is still active
 * - use kill(pid,0)
 *
 * return:
 *      0       -> success (lock file removed - no longer active
 *      FAIL    -> lock file still active
 */
GLOBAL int
cklock(char *name)
{
        int ret;
        pid_t lpid = -1;
        char alpid[SIZEOFPID+2];        /* +2 for '\n' and NULL */
        int fd;

        fd = open(name, O_RDONLY);
        DEBUG(4, "ulockf name %s\n", name);
        if (fd == -1) {
                if (errno == ENOENT)  /* file does not exist -- OK */
                        return (0);
                DEBUG(4, "Lock File--can't read (errno %d) --remove it!\n",
                    errno);
                goto unlk;
        }
        ret = read(fd, (char *)alpid, SIZEOFPID + 1); /* +1 for '\n' */
        (void) close(fd);
        if (ret != (SIZEOFPID+1)) {

                DEBUG(4, "Lock File--bad format--remove it!\n%s", "");
                goto unlk;
        }
        lpid = (pid_t)strtol(alpid, NULL, 10);
        if ((ret = kill(lpid, 0)) == 0 || errno == EPERM) {
                DEBUG(4, "Lock File--process still active--not removed\n%s",
                    "");
                return (FAIL);
        } else { /* process no longer active */
                DEBUG(4, "kill pid (%ld), ", (long)lpid);
                DEBUG(4, "returned %d", ret);
                DEBUG(4, "--ok to remove lock file (%s)\n", name);
        }
unlk:

        if (unlink(name) != 0) {
                DEBUG(4, "ulockf failed in unlink()\n%s", "");
                return (FAIL);
        }
        return (0);
}

#define MAXLOCKS 10     /* maximum number of lock files */
static char *Lockfile[MAXLOCKS];
GLOBAL int Nlocks = 0;

/*
 * put name in list of lock files
 * return:
 *      none
 */
static void
stlock(char *name)
{
        int i;
        char *p;

        for (i = 0; i < Nlocks; i++) {
                if (Lockfile[i] == NULL)
                        break;
        }
        ASSERT(i < MAXLOCKS, "TOO MANY LOCKS", "", i);
        if (i >= Nlocks)
                i = Nlocks++;
        p = calloc((unsigned)strlen(name) + 1, sizeof (char));
        ASSERT(p != NULL, "CAN NOT ALLOCATE FOR", name, 0);
        (void) strcpy(p, name);
        Lockfile[i] = p;
}

/*
 * remove the named lock. If named lock is NULL,
 *      then remove all locks currently in list.
 * return:
 *      none
 */
GLOBAL void
rmlock(char *name)
{
        int i;
#ifdef V8
        char *cp;

        cp = rindex(name, '/');
        if (cp++ != CNULL)
                if (strlen(cp) > MAXBASENAME)
                        *(cp+MAXBASENAME) = NULLCHAR;
#endif /* V8 */


        for (i = 0; i < Nlocks; i++) {
                if (Lockfile[i] == NULL)
                        continue;
                if (name == NULL || EQUALS(name, Lockfile[i])) {
                        (void) unlink(Lockfile[i]);
                        free(Lockfile[i]);
                        Lockfile[i] = NULL;
                }
        }
}



/*
 * remove a lock file
 *
 * Parameters:
 *      pre -   Path and first part of file name of the lock file to be
 *              removed.
 *      s -     The suffix part of the lock file.  The name of the lock file
 *              will be derrived by concatenating pre, a period, and s.
 *
 * return:
 *      none
 */
GLOBAL void
delock(char *pre, char *s)
{
        char ln[MAXNAMESIZE];

        (void) sprintf(ln, "%s.%s", pre, s);
        BASENAME(ln, '/')[MAXBASENAME] = '\0';
        rmlock(ln);
}


/*
 * create lock file
 *
 * Parameters:
 *      pre -   Path and first part of file name of the lock file to be
 *              created.
 *      name -  The suffix part of the lock file.  The name of the lock file
 *              will be derrived by concatenating pre, a period, and name.
 *
 * return:
 *      0       -> success
 *      FAIL    -> failure
 */
GLOBAL int
mlock(char *pre, char *name)
{
        char lname[MAXNAMESIZE];

        /*
         * if name has a '/' in it, then it's a device name and it's
         * not in /dev (i.e., it's a remotely-mounted device or it's
         * in a subdirectory of /dev).  in either case, creating our normal
         * lockfile (/var/spool/locks/LCK..<dev>) is going to bomb if
         * <dev> is "/remote/dev/term/14" or "/dev/net/foo/clone", so never
         * mind.  since we're using advisory filelocks on the devices
         * themselves, it'll be safe.
         *
         * of course, programs and people who are used to looking at the
         * lockfiles to find out what's going on are going to be a trifle
         * misled.  we really need to re-consider the lockfile naming structure
         * to accomodate devices in directories other than /dev ... maybe in
         * the next release.
         */
        if (strchr(name, '/') != NULL)
                return (0);
        (void) sprintf(lname, "%s.%s", pre, BASENAME(name, '/'));
        BASENAME(lname, '/')[MAXBASENAME] = '\0';
        return (mklock(lname));
}

/*
 * makes a lock on behalf of pid.
 * input:
 *      pid - process id
 *      tempfile - name of a temporary in the same file system
 *      name - lock file name (full path name)
 * return:
 *      -1 - failed
 *      0  - lock made successfully
 */
static int
onelock(char *pid, char *tempfile, char *name)
{
        int fd;
        char    cb[100];

        fd = creat(tempfile, (mode_t)0444);
        if (fd < 0) {
                (void) sprintf(cb, "%s %s %d", tempfile, name, errno);
                logent("ULOCKC", cb);
                if ((errno == EMFILE) || (errno == ENFILE))
                        (void) unlink(tempfile);
                return (-1);
        }
        /* +1 for '\n' */
        if (write(fd, pid, SIZEOFPID + 1) != (SIZEOFPID + 1)) {
                (void) sprintf(cb, "%s %s %d", tempfile, name, errno);
                logent("ULOCKW", cb);
                (void) unlink(tempfile);
                return (-1);
        }
        (void) chmod(tempfile, (mode_t)0444);
        (void) chown(tempfile, UUCPUID, UUCPGID);
        (void) close(fd);
        if (link(tempfile, name) < 0) {
                DEBUG(4, "%s: ", strerror(errno));
                DEBUG(4, "link(%s, ", tempfile);
                DEBUG(4, "%s)\n", name);
                if (unlink(tempfile) < 0) {
                        (void) sprintf(cb, "ULK err %s %d", tempfile,  errno);
                        logent("ULOCKLNK", cb);
                }
                return (-1);
        }
        if (unlink(tempfile) < 0) {
                (void) sprintf(cb, "%s %d", tempfile, errno);
                logent("ULOCKF", cb);
        }
        return (0);
}

/*
 * fd_mklock(fd) - lock the device indicated by fd is possible
 *
 * return -
 *      SUCCESS - this process now has the fd locked
 *      FAIL - this process was not able to lock the fd
 */

GLOBAL int
fd_mklock(int fd)
{
        int tries = 0;

        if (fstat(fd, &_st_buf) != 0)
                return (FAIL);

        (void) sprintf(lockname, "%s.%3.3lu.%3.3lu.%3.3lu", L_LOCK,
            (unsigned long) major(_st_buf.st_dev),
            (unsigned long) major(_st_buf.st_rdev),
            (unsigned long) minor(_st_buf.st_rdev));

        if (mklock(lockname) == FAIL)
                return (FAIL);

        while (lockf(fd, F_TLOCK, 0L) != 0) {
                DEBUG(7, "fd_mklock: lockf returns %d\n", errno);
                if ((++tries >= MAX_LOCKTRY) || (errno != EAGAIN)) {
                        rmlock(lockname);
                        logent("fd_mklock", "lockf failed");
                        return (FAIL);
                }
                (void) sleep(2);
        }
        DEBUG(7, "fd_mklock: ok\n%s", "");
        return (SUCCESS);
}

/*
 * fn_cklock(name) - determine if the device indicated by name is locked
 *
 * return -
 *      SUCCESS - the name is not locked
 *      FAIL - the name is locked by another process
 */

GLOBAL int
fn_cklock(char *name)
{
        /* we temporarily use lockname to hold full path name */
        (void) sprintf(lockname, "%s%s", (*name == '/' ? "" : "/dev/"), name);

        if (stat(lockname, &_st_buf) != 0)
                return (FAIL);

        (void) sprintf(lockname, "%s.%3.3lu.%3.3lu.%3.3lu", L_LOCK,
            (unsigned long) major(_st_buf.st_dev),
            (unsigned long) major(_st_buf.st_rdev),
            (unsigned long) minor(_st_buf.st_rdev));

        return (cklock(lockname));
}

/*
 * fd_cklock(fd) - determine if the device indicated by fd is locked
 *
 * return -
 *      SUCCESS - the fd is not locked
 *      FAIL - the fd is locked by another process
 */

GLOBAL int
fd_cklock(int fd)
{
        if (fstat(fd, &_st_buf) != 0)
                return (FAIL);

        (void) sprintf(lockname, "%s.%3.3lu.%3.3lu.%3.3lu", L_LOCK,
            (unsigned long) major(_st_buf.st_dev),
            (unsigned long) major(_st_buf.st_rdev),
            (unsigned long) minor(_st_buf.st_rdev));

        if (cklock(lockname) == FAIL)
                return (FAIL);
        else
                return (lockf(fd, F_TEST, 0L));
}

/*
 * remove the locks associated with the device file descriptor
 *
 * return -
 *      SUCCESS - both BNU lock file and advisory locks removed
 *      FAIL -
 */

GLOBAL void
fd_rmlock(int fd)
{
        if (fstat(fd, &_st_buf) == 0) {
                (void) sprintf(lockname, "%s.%3.3lu.%3.3lu.%3.3lu", L_LOCK,
                    (unsigned long) major(_st_buf.st_dev),
                    (unsigned long) major(_st_buf.st_rdev),
                    (unsigned long) minor(_st_buf.st_rdev));
                rmlock(lockname);
        }
        (void) lockf(fd, F_ULOCK, 0L);
}