Simplify libusb_fill_control_transfer()

Transfer length can be inferred from the setup packet.

diff --git a/examples/dpfp.c b/examples/dpfp.c
index a5151f2..c56e8d8 100644 (file)
--- a/examples/dpfp.c
+++ b/examples/dpfp.c
@@ -168,8 +168,7 @@ static void cb_mode_changed(struct libusb_transfer *transfer)
 
 static int set_mode_async(unsigned char data)
 {
-       int bufsize = LIBUSB_CONTROL_SETUP_SIZE + 1;
-       unsigned char *buf = malloc(bufsize);
+       unsigned char *buf = malloc(LIBUSB_CONTROL_SETUP_SIZE + 1);
        struct libusb_transfer *transfer;
 
        if (!buf)
@@ -184,8 +183,8 @@ static int set_mode_async(unsigned char data)
        printf("async set mode %02x\n", data);
        libusb_fill_control_setup(buf, CTRL_OUT, USB_RQ, 0x4e, 0, 1);
        buf[LIBUSB_CONTROL_SETUP_SIZE] = data;
-       libusb_fill_control_transfer(transfer, devh, buf, bufsize,
-               cb_mode_changed, NULL, 1000);
+       libusb_fill_control_transfer(transfer, devh, buf, cb_mode_changed, NULL,
+               1000);
 
        return libusb_submit_transfer(transfer);
 }

diff --git a/libusb/libusb.h b/libusb/libusb.h
index 3413301..a697e4e 100644 (file)
--- a/libusb/libusb.h
+++ b/libusb/libusb.h
@@ -270,15 +270,17 @@ void libusb_free_transfer(struct libusb_transfer *transfer);
 
 static inline void libusb_fill_control_transfer(
        struct libusb_transfer *transfer, libusb_device_handle *dev_handle,
-       unsigned char *buffer, int length, libusb_transfer_cb_fn callback,
-       void *user_data, unsigned int timeout)
+       unsigned char *buffer, libusb_transfer_cb_fn callback, void *user_data,
+       unsigned int timeout)
 {
+       struct libusb_control_setup *setup = (struct libusb_control_setup *) buffer;
        transfer->dev_handle = dev_handle;
        transfer->endpoint = 0;
        transfer->endpoint_type = LIBUSB_ENDPOINT_TYPE_CONTROL;
        transfer->timeout = timeout;
        transfer->buffer = buffer;
-       transfer->length = length;
+       if (setup)
+               transfer->length = LIBUSB_CONTROL_SETUP_SIZE + setup->wLength;
        transfer->user_data = user_data;
        transfer->callback = callback;
 }

diff --git a/libusb/sync.c b/libusb/sync.c
index d400470..bfff4e9 100644 (file)
--- a/libusb/sync.c
+++ b/libusb/sync.c
@@ -39,14 +39,13 @@ API_EXPORTED int libusb_control_transfer(libusb_device_handle *dev_handle,
 {
        struct libusb_transfer *transfer = libusb_alloc_transfer();
        unsigned char *buffer;
-       int length = wLength + LIBUSB_CONTROL_SETUP_SIZE;
        int completed = 0;
        int r;
 
        if (!transfer)
                return -ENOMEM;
        
-       buffer = malloc(length);
+       buffer = malloc(LIBUSB_CONTROL_SETUP_SIZE + wLength);
        if (!buffer) {
                libusb_free_transfer(transfer);
                return -ENOMEM;
@@ -57,7 +56,7 @@ API_EXPORTED int libusb_control_transfer(libusb_device_handle *dev_handle,
        if ((bRequestType & LIBUSB_ENDPOINT_DIR_MASK) == LIBUSB_ENDPOINT_OUT)
                memcpy(buffer + LIBUSB_CONTROL_SETUP_SIZE, data, wLength);
 
-       libusb_fill_control_transfer(transfer, dev_handle, buffer, length,
+       libusb_fill_control_transfer(transfer, dev_handle, buffer,
                ctrl_transfer_cb, &completed, timeout);
        r = libusb_submit_transfer(transfer);
        if (r < 0) {