libusbhost: Limit bulk transfer requests to 16384 bytes
Otherwise the kernel will return an EINVAL error
Change-Id: I906472a4128eb26c5be7865142bc4a52464cf5f8
Bug: 4065217
Signed-off-by: Mike Lockwood <lockwood@android.com>
diff --git a/libusbhost/usbhost.c b/libusbhost/usbhost.c
index f5a7c3f..b1c967d 100644
--- a/libusbhost/usbhost.c
+++ b/libusbhost/usbhost.c
@@ -53,6 +53,9 @@
#define USB_FS_ID_SCANNER "/dev/bus/usb/%d/%d"
#define USB_FS_ID_FORMAT "/dev/bus/usb/%03d/%03d"
+// From drivers/usb/core/devio.c
+// I don't know why this isn't in a kernel header
+#define MAX_USBFS_BUFFER_SIZE 16384
struct usb_host_context {
int fd;
@@ -477,6 +480,10 @@
{
struct usbdevfs_bulktransfer ctrl;
+ // need to limit request size to avoid EINVAL
+ if (length > MAX_USBFS_BUFFER_SIZE)
+ length = MAX_USBFS_BUFFER_SIZE;
+
memset(&ctrl, 0, sizeof(ctrl));
ctrl.ep = endpoint;
ctrl.len = length;
@@ -531,7 +538,11 @@
urb->status = -1;
urb->buffer = req->buffer;
- urb->buffer_length = req->buffer_length;
+ // need to limit request size to avoid EINVAL
+ if (req->buffer_length > MAX_USBFS_BUFFER_SIZE)
+ urb->buffer_length = MAX_USBFS_BUFFER_SIZE;
+ else
+ urb->buffer_length = req->buffer_length;
do {
res = ioctl(req->dev->fd, USBDEVFS_SUBMITURB, urb);