/*	$eterna: fdiscard-stuff.c,v 1.3 2020/12/25 23:40:19 mrg Exp $	*/

/*
 * Copyright (c) 2019, 2020 Matthew R. Green
 * All rights reserved.
 *
 * 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. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
 */

/* fdiscard(2) front-end -- TRIM support. */

#include <sys/param.h>
#include <sys/stat.h>
#include <sys/disk.h>
#include <sys/disklabel.h>
#include <sys/ioctl.h>

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <err.h>
#include <errno.h>
#include <assert.h>

static void
usage(const char* msg)
{
	/*
	 * -f first byte to discard.
	 * -s end offset.  total length is end_offset - first_byte.
	 * -R actually run it, default is no-run.
	 * -m max size to pass to fdiscard(2).  loops over this.
	 */
	fprintf(stderr, "%sUsage: fdiscard [-R] [-f first_byte] [-s end_offset] [-m max_per_call] <file>\n", msg);
	exit(1);
}

int
main(int argc, char *argv[])
{
	int norun = 1;
	off_t first_byte = 0, end_offset = 0;
	off_t max_per_call = 32 * 1024 * 1024;
	off_t discard_size;
	off_t size = 0;
	char *ep;
	int64_t val;
	int i;

	while ((i = getopt(argc, argv, "f:m:Rs:")) != -1) {
		switch (i) {
		case 'R':
			norun = 0;
			break;
		case 'f':
			if (dehumanize_number(optarg, &val) == -1 || val < 0)
				usage("bad -f\n");
			first_byte = val;
			break;
		case 'm':
			if (dehumanize_number(optarg, &val) == -1 || val < 0)
				usage("bad -m\n");
			max_per_call = val;
			break;
		case 's':
			if (dehumanize_number(optarg, &val) == -1 || val < 0)
				usage("bad -s\n");
			end_offset = val;
			break;
		default:
			usage("bad options\n");
		}
	}
	argc -= optind;
	argv += optind;

	if (argc != 1)
		usage("not one arg left\n");

	char *name = argv[0];
	int fd = open(name, O_RDWR);
	if (fd < 0)
		err(1, "open on %s", name);

	if (size == 0) {
		struct dkwedge_info dkw;
		if (ioctl(fd, DIOCGWEDGEINFO, &dkw) == 0) {
			size = dkw.dkw_size * DEV_BSIZE;
			printf("wedge size is %lld\n", size);
		}
	}

	if (size == 0) {
		struct disklabel dl;
		if (ioctl(fd, DIOCGDINFO, &dl) != -1) {
			char partchar = name[strlen(name)-1];
			assert(partchar >= 'a' && partchar <= 'p');
			int part = partchar - 'a';

			size = (uint64_t)dl.d_partitions[part].p_size * dl.d_secsize;
			printf("disklabel size is %lld\n", size);
		}
	}

	if (size == 0) {
		struct stat sb;
		if (fstat(fd, &sb) != -1) {
			size = sb.st_size;
			printf("stat size is %lld\n", size);
		}
	}

	if (size == 0) {
		fprintf(stderr, "unable to determine size.\n");
		exit(1);
	}
	printf("size = %lld\n", size);

	size -= first_byte;

	if (end_offset) {
		if (end_offset > size) {
			fprintf(stderr, "end_offset %lld > size %lld\n", end_offset, size);
			usage("");
		}
		size = end_offset;
	}

	printf("%sgoing to fdiscard on %s from %lld for %lld, %lld at a time\n", norun ? "not " : "", name, first_byte, size, max_per_call);

	int loop = 0;
	while (size > 0) {
		if (size > max_per_call)
			discard_size = max_per_call;
		else
			discard_size = size;
		if (norun == 0) {
			if (fdiscard(fd, first_byte, discard_size) == -1)
				err(1, "fdiscard");
		}
		first_byte += discard_size;
		size -= discard_size;
		printf(".");
		if (loop++ > 100) {
			loop = 0;
			printf("\n");
		}
	}
	if (loop != 0)
		printf("\n");

	return 0;
}