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Add 500ms max wait time for hid_write to complete on Windows

It appears that with some (presumably) flaky drivers or hardware that the WriteFile in hid_write never completes leading to GetOverlappedResult to block forever waiting for it.
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slouken committed Mar 3, 2020
1 parent 07000bf commit 96836ec643b2b01d459ebaa6dae559acae7caec1
Showing with 25 additions and 5 deletions.
  1. +25 −5 src/hidapi/windows/hid.c
@@ -63,6 +63,11 @@ typedef LONG NTSTATUS;

/*#define HIDAPI_USE_DDK*/

/* The timeout in milliseconds for waiting on WriteFile to
complete in hid_write. The longest observed time to do a output
report that we've seen is ~200-250ms so let's double that */
#define HID_WRITE_TIMEOUT_MILLISECONDS 500

#ifdef __cplusplus
extern "C" {
#endif
@@ -163,6 +168,7 @@ struct hid_device_ {
BOOL read_pending;
char *read_buf;
OVERLAPPED ol;
OVERLAPPED write_ol;
};

static hid_device *new_hid_device()
@@ -178,13 +184,16 @@ static hid_device *new_hid_device()
dev->read_buf = NULL;
memset(&dev->ol, 0, sizeof(dev->ol));
dev->ol.hEvent = CreateEvent(NULL, FALSE, FALSE /*initial state f=nonsignaled*/, NULL);
memset(&dev->write_ol, 0, sizeof(dev->write_ol));
dev->write_ol.hEvent = CreateEvent(NULL, FALSE, FALSE /*initial state f=nonsignaled*/, NULL);

return dev;
}

static void free_hid_device(hid_device *dev)
{
CloseHandle(dev->ol.hEvent);
CloseHandle(dev->write_ol.hEvent);
CloseHandle(dev->device_handle);
LocalFree(dev->last_error_str);
free(dev->read_buf);
@@ -678,14 +687,12 @@ int HID_API_EXPORT HID_API_CALL hid_write_output_report(hid_device *dev, const u
return -1;
}

int HID_API_EXPORT HID_API_CALL hid_write(hid_device *dev, const unsigned char *data, size_t length)
static int hid_write_timeout(hid_device *dev, const unsigned char *data, size_t length, int milliseconds)
{
DWORD bytes_written;
BOOL res;
size_t stashed_length = length;
OVERLAPPED ol;
unsigned char *buf;
memset(&ol, 0, sizeof(ol));

/* Make sure the right number of bytes are passed to WriteFile. Windows
expects the number of bytes which are in the _longest_ report (plus
@@ -710,7 +717,7 @@ int HID_API_EXPORT HID_API_CALL hid_write(hid_device *dev, const unsigned char *
}
else
{
res = WriteFile( dev->device_handle, buf, ( DWORD ) length, NULL, &ol );
res = WriteFile( dev->device_handle, buf, ( DWORD ) length, NULL, &dev->write_ol );
if (!res) {
if (GetLastError() != ERROR_IO_PENDING) {
/* WriteFile() failed. Return error. */
@@ -722,7 +729,16 @@ int HID_API_EXPORT HID_API_CALL hid_write(hid_device *dev, const unsigned char *

/* Wait here until the write is done. This makes
hid_write() synchronous. */
res = GetOverlappedResult(dev->device_handle, &ol, &bytes_written, TRUE/*wait*/);
res = WaitForSingleObject(dev->write_ol.hEvent, milliseconds);
if (res != WAIT_OBJECT_0)
{
// There was a Timeout.
bytes_written = (DWORD) -1;
register_error(dev, "WriteFile/WaitForSingleObject Timeout");
goto end_of_function;
}

res = GetOverlappedResult(dev->device_handle, &dev->write_ol, &bytes_written, FALSE/*F=don't_wait*/);
if (!res) {
/* The Write operation failed. */
register_error(dev, "WriteFile");
@@ -737,6 +753,10 @@ int HID_API_EXPORT HID_API_CALL hid_write(hid_device *dev, const unsigned char *
return bytes_written;
}

int HID_API_EXPORT HID_API_CALL hid_write(hid_device *dev, const unsigned char *data, size_t length)
{
return hid_write_timeout(dev, data, length, HID_WRITE_TIMEOUT_MILLISECONDS);
}

int HID_API_EXPORT HID_API_CALL hid_read_timeout(hid_device *dev, unsigned char *data, size_t length, int milliseconds)
{

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