/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2019 Eugene Grosbein <eugen@FreeBSD.org>.
 * Contains code written by Alan Somers <asomers@FreeBSD.org>.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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/disk.h>
#include <sys/ioctl.h>
#include <sys/stat.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <libutil.h>
#include <limits.h>
#include <paths.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>

#include <sys/cdefs.h>
static bool     candelete(int fd);
static off_t    getsize(const char *path);
static int      opendev(const char *path, int flags);
static int      trim(const char *path, off_t offset, off_t length, bool dryrun, bool verbose);
static void     usage(const char *name);

int
main(int argc, char **argv)
{
        off_t offset, length;
        uint64_t usz;
        int ch, error;
        bool dryrun, verbose;
        char *fname, *name;

        error = 0;
        length = offset = 0;
        name = argv[0];
        dryrun = verbose = true;

        while ((ch = getopt(argc, argv, "Nfl:o:qr:v")) != -1)
                switch (ch) {
                case 'N':
                        dryrun = true;
                        verbose = true;
                        break;
                case 'f':
                        dryrun = false;
                        break;
                case 'l':
                case 'o':
                        if (expand_number(optarg, &usz) == -1 ||
                                        (off_t)usz < 0 || (usz == 0 && ch == 'l'))
                                errx(EX_USAGE,
                                        "invalid %s of the region: %s",
                                        ch == 'o' ? "offset" : "length",
                                        optarg);
                        if (ch == 'o')
                                offset = (off_t)usz;
                        else
                                length = (off_t)usz;
                        break;
                case 'q':
                        verbose = false;
                        break;
                case 'r':
                        if ((length = getsize(optarg)) == 0)
                                errx(EX_USAGE,
                                        "invalid zero length reference file"
                                        " for the region: %s", optarg);
                        break;
                case 'v':
                        verbose = true;
                        break;
                default:
                        usage(name);
                        /* NOTREACHED */
                }

        /*
         * Safety net: do not allow mistakes like
         *
         *      trim -f /dev/da0 -r rfile
         *
         * This would trim whole device then error on non-existing file -r.
         * Following check prevents this while allowing this form still:
         *
         *      trim -f -- /dev/da0 -r rfile
         */

        if (strcmp(argv[optind-1], "--") != 0) {
                for (ch = optind; ch < argc; ch++)
                        if (argv[ch][0] == '-')
                                usage(name);
        }

        argv += optind;
        argc -= optind;

        if (argc < 1)
                usage(name);

        if (dryrun)
                printf("dry run: add -f to actually perform the operation\n");

        while ((fname = *argv++) != NULL)
                if (trim(fname, offset, length, dryrun, verbose) < 0)
                        error++;

        return (error ? EXIT_FAILURE : EXIT_SUCCESS);
}

static bool
candelete(int fd)
{
        struct diocgattr_arg arg;

        strlcpy(arg.name, "GEOM::candelete", sizeof(arg.name));
        arg.len = sizeof(arg.value.i);
        if (ioctl(fd, DIOCGATTR, &arg) == 0)
                return (arg.value.i != 0);
        else
                return (false);
}

static int
opendev(const char *path, int flags)
{
        int fd;
        char *tstr;

        if ((fd = open(path, flags)) < 0) {
                if (errno == ENOENT && path[0] != '/') {
                        if (asprintf(&tstr, "%s%s", _PATH_DEV, path) < 0)
                                errx(EX_OSERR, "no memory");
                        fd = open(tstr, flags);
                        free(tstr);
                }
        }

        if (fd < 0)
                err(EX_NOINPUT, "open failed: %s", path);

        return (fd);
}

static off_t
getsize(const char *path)
{
        struct stat sb;
        off_t mediasize;
        int fd;

        fd = opendev(path, O_RDONLY | O_DIRECT);

        if (fstat(fd, &sb) < 0)
                err(EX_IOERR, "fstat failed: %s", path);

        if (S_ISREG(sb.st_mode) || S_ISDIR(sb.st_mode)) {
                close(fd);
                return (sb.st_size);
        }

        if (!S_ISCHR(sb.st_mode) && !S_ISBLK(sb.st_mode))
                errx(EX_DATAERR,
                        "invalid type of the file "
                        "(not regular, directory nor special device): %s",
                        path);

        if (ioctl(fd, DIOCGMEDIASIZE, &mediasize) < 0)
                err(EX_UNAVAILABLE,
                        "ioctl(DIOCGMEDIASIZE) failed, probably not a disk: "
                        "%s", path);

        close(fd);
        return (mediasize);
}

static int
trim(const char *path, off_t offset, off_t length, bool dryrun, bool verbose)
{
        off_t arg[2];
        int error, fd;

        if (length == 0)
                length = getsize(path);

        if (verbose)
                printf("trim %s offset %ju length %ju\n",
                    path, (uintmax_t)offset, (uintmax_t)length);

        if (dryrun)
                return (0);

        fd = opendev(path, O_RDWR | O_DIRECT);
        arg[0] = offset;
        arg[1] = length;

        error = ioctl(fd, DIOCGDELETE, arg);
        if (error < 0) {
                if (errno == EOPNOTSUPP && verbose && !candelete(fd))
                        warnx("%s: TRIM/UNMAP not supported by driver", path);
                else
                        warn("ioctl(DIOCGDELETE) failed: %s", path);
        }
        close(fd);
        return (error);
}

static void
usage(const char *name)
{
        (void)fprintf(stderr,
            "usage: %s [-[lo] offset[K|k|M|m|G|g|T|t|P|p|E|e]] [-r rfile] [-Nfqv] device ...\n",
            name);
        exit(EX_USAGE);
}