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#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
int main()
{
char buf[409600];
ssize_t r;
int err;
int fd = open("shortfile", O_WRONLY|O_CREAT, 0644);
if (fd < 0) {
err = errno;
printf("error: open() failed with: %d (%s)\n", err, strerror(err));
exit(err);
}
printf("writing first 3 bytes of 10k file\n");
r = write(fd, "foo", 3);
if (r == -1) {
err = errno;
printf("error: write() failed with: %d (%s)\n", err, strerror(err));
close(fd);
exit(err);
}
r = ftruncate(fd, 10000);
if (r == -1) {
err = errno;
printf("error: ftruncate() failed with: %d (%s)\n", err, strerror(err));
close(fd);
exit(err);
}
fsync(fd);
close(fd);
printf("reading O_DIRECT\n");
fd = open("shortfile", O_RDONLY|O_DIRECT);
if (fd < 0) {
err = errno;
printf("error: open() failed with: %d (%s)\n", err, strerror(err));
exit(err);
}
r = read(fd, buf, sizeof(buf));
close(fd);
printf("got %d\n", (int)r);
if (r != 10000)
return 1;
return 0;
}
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