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#include <sys/file.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int
main(int argc, char *argv[])
{
int fd = -1;
char *filename = NULL;
struct flock lock = {
0,
};
int i = 0;
int ret = -1;
if (argc != 2) {
fprintf(stderr, "Usage: %s <filename> ", argv[0]);
goto out;
}
filename = argv[1];
fd = open(filename, O_RDWR | O_CREAT, 0);
if (fd < 0) {
fprintf(stderr, "open (%s) failed (%s)\n", filename, strerror(errno));
goto out;
}
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 1;
lock.l_len = 1;
while (i < 100) {
lock.l_type = F_WRLCK;
ret = fcntl(fd, F_SETLK, &lock);
if (ret < 0) {
fprintf(stderr, "fcntl setlk failed (%s)\n", strerror(errno));
goto out;
}
lock.l_type = F_UNLCK;
ret = fcntl(fd, F_SETLK, &lock);
if (ret < 0) {
fprintf(stderr, "fcntl setlk failed (%s)\n", strerror(errno));
goto out;
}
i++;
}
ret = 0;
out:
return ret;
}
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