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POC & Android kernel module: what happened with f_flags here?
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copied!<p>I have a self-coded kernel module in Android which I open with <code>O_RDONLY|O_NONBLOCK</code>.</p> <p><code>O_NONBLOCK</code> is <code>2048</code> in both the user-program and the kernel module.</p> <p>I checked that with </p> <pre><code>print..("O_NONBLOCK is %d", O_NONBLOCK) </code></pre> <p>in user- & kernel-space.</p> <p>But now, when I try to check if <code>O_NONBLOCK</code> was set, I got a really strange problem:</p> <pre><code>static int my_open(struct inode *inode, struct file *filp) { if (filp->f_flags & O_NONBLOCK) { printk("O_NONBLOCK"); } else { printk("NOT O_NONBLOCK"); printk("O_NONBLOCK in my_open is: %d", O_NONBLOCK); // -> prints 2048 printk("filp->f_flags in my_open is: %d", filp->f_flags); // -> prints 1, not 2048 or larger } .. } </code></pre> <p>I tried something else:</p> <pre><code>cat my_device </code></pre> <p>but again, <code>filp->f_flags</code> is <code>1</code>.</p> <p>I would assume maybe <code>0</code> for <code>O_RDONLY</code> but not <code>1</code> which means <code>O_WRONLY</code>.</p> <p>Anyone an idea or explanation?</p> <p>EDIT:</p> <p>I also <strong>don't</strong> expect <code>cat</code> beeing <code>O_NONBLOCK</code>, but <code>O_WRONLY</code> is totally wrong. </p> <p>I open it this way: </p> <pre><code>pcm->dfd=open(fname, O_RDONLY|O_NONBLOCK); </code></pre> <p>and there's no <code>fcntl</code> later (and that shouldn't affect <code>my_open</code> at all. But of course I also tried to "re-set" <code>O_NONBLOCK</code> with <code>fcntl</code> without luck.</p>

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