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POModify libusb to accept file descriptor
 

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  1. POModify libusb to accept file descriptor
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    <p>I modified libusb1.0 open function as follows:</p> <pre><code>static int op_open2(struct libusb_device_handle *handle, int fd) { struct linux_device_handle_priv *hpriv = _device_handle_priv(handle); hpriv-&gt;fd = fd; return usbi_add_pollfd(HANDLE_CTX(handle), hpriv-&gt;fd, POLLOUT); } </code></pre> <p>where fd was obtained via <a href="http://developer.android.com/reference/android/hardware/usb/UsbDeviceConnection.html#getFileDescriptor%28%29" rel="nofollow">android.hardware.usb.UsbDeviceConnection.html#getFileDescriptor()</a></p> <pre><code>final UsbDeviceConnection connection = manager.openDevice(device); return connection.getFileDescriptor(); </code></pre> <p>Unfortunatelly I keep getting an error when I call</p> <pre><code>static int op_claim_interface(struct libusb_device_handle *handle, int iface) { int fd = _device_handle_priv(handle)-&gt;fd; int r = ioctl(fd, IOCTL_USBFS_CLAIMINTF, &amp;iface); if (r) { if (errno == ENOENT) return LIBUSB_ERROR_NOT_FOUND; else if (errno == EBUSY) return LIBUSB_ERROR_BUSY; else if (errno == ENODEV) return LIBUSB_ERROR_NO_DEVICE; usbi_err(HANDLE_CTX(handle), "claim interface failed, error %d errno %d", r, errno); return LIBUSB_ERROR_OTHER; } return 0; } </code></pre> <p><strong>claim interface failed, error -1 errno 9</strong></p> <p>which is translated to "Bad file number". The file descriptor I get from Java is a positive integer!</p> <p>The only other small detail is that my native code runs as a separate binary that is spawned with a Java ProcessBuilder. But they share the same uid, so I presume the USB permissions I have from Java should still apply for libusb.</p> <p>I don't need to be platform independent, so any hacks would do the job :)</p> <p>Any thoughts would be much appreciated!</p> <p>Additional information! The output I get from <strong>lsof</strong> is (shortened to stress the most interesting part of it)</p> <pre><code>my.activity 13374 u0_a62 exe ??? ??? ??? ??? /system/bin/app_process my.activity 13374 u0_a62 0 ??? ??? ??? ??? /dev/null my.activity 13374 u0_a62 1 ??? ??? ??? ??? /dev/null my.activity 13374 u0_a62 2 ??? ??? ??? ??? /dev/null my.activity 13374 u0_a62 3 ??? ??? ??? ??? /dev/log/main my.activity 13374 u0_a62 4 ??? ??? ??? ??? /dev/log/radio my.activity 13374 u0_a62 5 ??? ??? ??? ??? /dev/log/events my.activity 13374 u0_a62 6 ??? ??? ??? ??? /dev/log/system my.activity 13374 u0_a62 7 ??? ??? ??? ??? /system/framework/core.jar my.activity 13374 u0_a62 8 ??? ??? ??? ??? /system/framework/core-junit.jar my.activity 13374 u0_a62 9 ??? ??? ??? ??? /dev/__properties__ (deleted) ... my.activity 13374 u0_a62 44 ??? ??? ??? ??? /dev/bus/usb/002/002 ... my.activity 13374 u0_a62 51 ??? ??? ??? ??? pipe:[51015] my.activity 13374 u0_a62 53 ??? ??? ??? ??? pipe:[51016] ... my_exe 13546 u0_a62 exe ??? ??? ??? ??? /data/data/my.activity/files/my_exe my_exe 13546 u0_a62 0 ??? ??? ??? ??? pipe:[51015] my_exe 13546 u0_a62 1 ??? ??? ??? ??? pipe:[51016] my_exe 13546 u0_a62 2 ??? ??? ??? ??? pipe:[51016] my_exe 13546 u0_a62 3 ??? ??? ??? ??? /dev/log/main my_exe 13546 u0_a62 4 ??? ??? ??? ??? /dev/log/radio my_exe 13546 u0_a62 5 ??? ??? ??? ??? /dev/log/events my_exe 13546 u0_a62 6 ??? ??? ??? ??? /dev/log/system my_exe 13546 u0_a62 9 ??? ??? ??? ??? /dev/__properties__ (deleted) my_exe 13546 u0_a62 mem ??? b3:09 0 302530 /data/data/my.activity/files/my_exe my_exe 13546 u0_a62 mem ??? b3:09 36864 302530 /data/data/my.activity/files/my_exe my_exe 13546 u0_a62 mem ??? b3:09 40960 302530 /data/data/my.activity/files/my_exe my_exe 13546 u0_a62 mem ??? b3:03 0 200 /system/bin/linker my_exe 13546 u0_a62 mem ??? b3:03 57344 200 /system/bin/linker my_exe 13546 u0_a62 mem ??? b3:03 61440 200 /system/bin/linker </code></pre> <p>Which makes me think that the file descriptor 44 that I pass to my_exe is actually not inherited!</p>
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