#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>

/*
 * Usage: cp-catalog <read_size>
 *
 * Read the catalog from beginning to end. Read 'read_size' bytes
 * on each read.
 *
 * To ensure that a bug in catalog_read() in the kernel code is fixed.
 * 	cp-catalog 5 > /tmp/catalog-5
 * 	cp-catalog  > /tmp/catalog-4096
 * 	diff /tmp/catalog-5 /tmp/catalog-4096
 *
 * If both files are identical and size is about 256K, the bug is fixed.
 */
#define CATALOG	"/sys/bus/event_source/devices/hv_24x7/interface/catalog"
#define TMP_CATALOG	"/tmp/catalog"

main(int argc, char *argv[])
{
	int read_size, rfd, wfd, rc;
	struct stat stat_buf;
	char *input_file;
	char buf[4096];
	char output_file[256];

	read_size = 4096;
	if (argc > 1)
		read_size = atoi(argv[1]);

	if (read_size > sizeof(buf))
		read_size = sizeof(buf);

	input_file = CATALOG;
	sprintf(output_file, "%s-%d", TMP_CATALOG, read_size);

	rfd = open(input_file, O_RDONLY);
	if (rfd < 0) {
		perror(input_file);
		_Exit(1);
	}

	wfd  = open(output_file, O_WRONLY|O_CREAT|O_TRUNC);
	if (wfd < 0) {
		perror(output_file);
		_Exit(1);
	}

	while(1) {
		memset(buf, 0, sizeof(buf));
		rc = read(rfd, buf, read_size);
		if (rc <= 0)
			break;
		if (write(wfd, buf, rc) != rc) {
			perror("write()");
			break;
		}
	}
	if (fstat(wfd, &stat_buf) < 0) {
		perror("fstat()");
		_Exit(1);
	}
	printf("catalog size %zd\n", stat_buf.st_size);
}