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#define _GNU_SOURCE
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <string.h>
/* needs to be multiple of softblock size of filesystem */
#define SIZE (512 * 32)
void usage(char *command)
{
fprintf(stderr, "usage: %s FILENAME SIZE\n", command);
exit(1);
}
int main(int argc, char *argv[])
{
int fd;
void *address;
if (argc != 3) usage(argv[0]);
if ((fd = open(argv[1], O_CREAT | O_DIRECT | O_RDWR, 0666)) < 0) {
fprintf(stderr, "ERROR: failed to open `%s': %s \n",
argv[1], strerror(errno));
exit(1);
} else {
/* Align memory -- required by O_DIRECT flag */
int ret = posix_memalign(&address, SIZE, SIZE);
if (ret < 0) {
close(fd);
return -1;
}
memset(address, atoi(argv[2]), SIZE);
/* fillup the memory in chunks of SIZE */
while(write(fd, address, SIZE) > 0){};
close(fd);
}
return 0;
}
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