/*
 * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@backplane.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name of The DragonFly Project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific, prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/event.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>

typedef struct monitor_elm {
        const char *path;
        int     fd;
} *monitor_elm_t;

static void usage(int exit_code);
static void monitor_add(const char *path);
static void monitor_events(void);

static int VerboseOpt;
static int QuietOpt;
static int ExitOpt;
static int KQueueFd;
static int NumFiles;
static int MaxFiles;
static monitor_elm_t *Elms;

int
main(int ac, char **av)
{
        int ch;
        int i;

        while ((ch = getopt(ac, av, "qvx")) != -1) {
                switch (ch) {
                case 'q':
                        if (VerboseOpt > 0)
                                --VerboseOpt;
                        else
                                ++QuietOpt;
                        break;
                case 'v':
                        if (QuietOpt > 0)
                                --QuietOpt;
                        else
                                ++VerboseOpt;
                        break;
                case 'x':
                        ExitOpt = 1;
                        break;
                default:
                        usage(1);
                        /* not reached */
                }
        }
        ac -= optind;
        av += optind;

        if (ac < 1) {
                usage(1);
                /* not reached */
        }

        if ((KQueueFd = kqueue()) < 0) {
                perror("kqueue");
                exit(1);
        }
        NumFiles = MaxFiles = 16;
        Elms = calloc(MaxFiles, sizeof(monitor_elm_t));

        for (i = 0; i < ac; ++i) {
                monitor_add(av[i]);
        }
        fflush(stdout);
        do {
                monitor_events();
                fflush(stdout);
        } while (ExitOpt == 0);
        exit(0);
}

static
void
monitor_add(const char *path)
{
        monitor_elm_t elm;
        struct kevent kev;
        int n;

        elm = malloc(sizeof(*elm));
        bzero(elm, sizeof(*elm));
        elm->path = path;
        elm->fd = open(path, O_RDONLY);
        if (elm->fd < 0) {
                printf("%s\tnot found\n", path);
                return;
        }
        EV_SET(&kev, elm->fd, EVFILT_VNODE, EV_ADD|EV_ENABLE|EV_CLEAR,
               NOTE_DELETE|NOTE_WRITE|NOTE_EXTEND|NOTE_ATTRIB|
               NOTE_LINK|NOTE_RENAME|NOTE_REVOKE,
               0, NULL);
        n = kevent(KQueueFd, &kev, 1, NULL, 0, NULL);
        if (n < 0) {
                perror("kqueue");
                exit(1);
        }

        if (elm->fd >= NumFiles) {
                MaxFiles = (elm->fd + 16) * 3 / 2;
                Elms = realloc(Elms, MaxFiles * sizeof(elm));
                bzero(&Elms[NumFiles], (MaxFiles - NumFiles) * sizeof(elm));
                NumFiles = MaxFiles;
        }
        Elms[elm->fd] = elm;
}

static
void
monitor_events(void)
{
        struct kevent kev_array[1];
        struct kevent *kev;
        monitor_elm_t elm;
        struct stat st;
        int bno;
        int i;
        int n;

        n = kevent(KQueueFd, NULL, 0, kev_array, 1, NULL);
        for (i = 0; i < n; ++i) {
                kev = &kev_array[i];
                elm = Elms[kev->ident];
                printf("%-23s", elm->path);
                if (VerboseOpt && fstat(kev->ident, &st) == 0 &&
                    S_ISREG(st.st_mode)) {
                        printf(" %10jd", (intmax_t)st.st_size);
                }
                while (QuietOpt == 0 && (bno = ffs(kev->fflags)) > 0) {
                        printf(" ");
                        --bno;
                        kev->fflags &= ~(1 << bno);
                        switch (1 << bno) {
                        case NOTE_DELETE:
                                printf("delete");
                                break;
                        case NOTE_WRITE:
                                printf("write");
                                break;
                        case NOTE_EXTEND:
                                printf("extend");
                                break;
                        case NOTE_ATTRIB:
                                printf("attrib");
                                break;
                        case NOTE_LINK:
                                printf("link");
                                break;
                        case NOTE_RENAME:
                                printf("rename");
                                break;
                        case NOTE_REVOKE:
                                printf("revoke");
                                break;
                        default:
                                printf("%08x", 1 << bno);
                                break;
                        }
                }
                printf("\n");
        }
}

static
void
usage(int exit_code)
{
        fprintf(stderr,
                "monitor [-vx] files...\n"
                "    -v      Be more verbose\n"
                "    -x      Exit after first event reported\n"
        );
        exit(exit_code);
}