linhex.c

能够在linux下指定的文件进行内容写零再删除

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

const int BUFSIZE = 1024;
//#define CHECK

int
main(int argc, char *argv[]) {

	int fd, i, j, len = 0, level;
	struct stat info;
	void *area;

	if (argc < 2) {
		printf("please enter at least a argument!\n");
		exit(1);
	}

#ifdef CHECK
	for (i = 0; i <= argc; ++i)
		printf("[%i]%s\n", i, argv[i]);
#endif

	level = 1;
	for (i = 0; i < argc; ++i) {
		if (!strncmp(argv[i], "-n", 2)) {
			level = atoi(argv[i + 1]);
			for (j = i; j < argc - i + 2; ++j) {
				argv[j] = argv[j + 2];
			}
			argc -= 2;
			break;
		}
	}

#ifdef CHECK
	for (i = 0; i <= argc; ++i)
		printf("[%i]%s\n", i, argv[i]);
#endif

	for (i = 1; i < argc; ++i) {
		fd = open(argv[i], O_RDWR);
		printf("file %s has been opened!\n", argv[i]);

		fstat(fd, &info);
		len = info.st_size;
		printf("the length of file %s is %i bytes!\n", argv[i], len);
		if (len != 0) {
			area = mmap(0, len, PROT_WRITE, MAP_SHARED, fd, 0);
			if (area == MAP_FAILED) {
				perror("mmap");
				exit(1);
			}
			for (j = 0; j < level; ++j) {
				memset(area, 0x00, len);
				msync(area, len, MS_SYNC);
				printf("file %s has zeroed %i times!\n", argv[i], j + 1);
			}
			munmap(area, len);
			close(fd);
			printf("file %s has been closed!\n", argv[i]);
		}
		else {
			close(fd);
		}
		rename(argv[i], "./abcde");
		sync();
		printf("file %s has been renamed!\n", argv[i]);
		unlink("./abcde");
		printf("file %s has been deleted!\n", argv[i]);
	}
	return 0;
}