/* get_coverage - program to get coverage informations from Xen
 * 
 * Copyright (C) 2013  - Citrix Systems
 * -----
 *
 * 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 <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <inttypes.h>
#include <sys/mman.h>
#include <err.h>

typedef struct privcmd_hypercall
{
	uint64_t op;
	uint64_t arg[5];
} privcmd_hypercall_t;

#define IOCTL_PRIVCMD_HYPERCALL								 \
	_IOC(_IOC_NONE, 'P', 0, sizeof(privcmd_hypercall_t))

#define PAGE_SIZE 4096u

static int privcmd_fd = -1;

int get_gcov_info(int op, void *ptr)
{
	privcmd_hypercall_t hc[1];
	int ret;

	hc->op = 40; // TODO
	hc->arg[0] = op;
	hc->arg[1] = (intptr_t) ptr;
	ret = ioctl(privcmd_fd, IOCTL_PRIVCMD_HYPERCALL, hc);
	if (ret >= 0)
		return ret;
	return -errno;
}

int main(void)
{
	// open priv command
	privcmd_fd = open("/proc/xen/privcmd", O_RDWR);
	if (privcmd_fd < 0)
		err(1, "opening privcmd");

	// check support
	if (get_gcov_info(0, NULL) < 0)
		err(1, "checking coverage support");

	// allocate
	uint8_t *p = mmap(0, PAGE_SIZE, PROT_WRITE|PROT_READ, MAP_PRIVATE|MAP_ANON|MAP_LOCKED, -1, 0);
	if (p == (uint8_t *) -1)
		err(1, "allocating memory");

	// get total length
	uint32_t *ui = (uint32_t *) p;
	*ui = 0;
	if (get_gcov_info(1, ui) < 0)
		err(1, "getting total length");
	printf("returned %u bytes\n", (unsigned) *ui);

	// safe check
	uint32_t total_len = *ui;
	if (total_len > 16u * 1024u * 1024u)
		errx(1, "coverage size too big %u bytes\n", total_len);

	// reallocate
	munmap(p, PAGE_SIZE);
	size_t size = total_len + PAGE_SIZE;
	size -= (size % PAGE_SIZE);
	p = mmap(0, size, PROT_WRITE|PROT_READ, MAP_PRIVATE|MAP_ANON|MAP_LOCKED, -1, 0);
	if (p == (uint8_t *) -1)
		err(1, "mapping memory for coverage");

	// get data
	if (get_gcov_info(2, p) < 0)
		err(1, "getting coverage information");

	// write to a file
	FILE *f = fopen("gcda.dat", "w");
	if (!f)
		err(1, "opening output file");
	if (fwrite(p, 1, total_len, f) != total_len)
		err(1, "writing coverage to file");
	fclose(f);

	return 0;
}