How to check if a file has been opened by another application in C++?

Question

I know, that there\'s the is_open() function in C++, but I want one program to check if a file hasn\'t been opened by another application. Is there any way to d

Answer 1

The following code may work.

int main(int argc, char ** argv)
{
    int fd = open(argv[1], O_RDONLY);
    if (fd < 0) {
        perror("open");
        return 1;
    }

    if (fcntl(fd, F_SETLEASE, F_WRLCK) && EAGAIN == errno) {
        puts("file has been opened");
    }
    else {
        fcntl(fd, F_SETLEASE, F_UNLCK);
        puts("file has not been opened");
    }

    close(fd);
    return 0;
}