all: Make usbi_os_backend.get_[active_]config_descriptor return len

Since commit 5e479f1821d3294fb1cc70c5867c69eca2551de7:
"Core: Avoid short read failures on broken descriptors"

usbi_os_backend.get_[active_]config_descriptor no longer return on error
(under Linux) when returning less bytes then requested. But
libusb_get_[active_]config_descriptor still not only requests wTotalLength
bytes, but also blindly assumes that on success it has gotten wTotalLength
bytes.

This patch fixes this, it changes all usbi_os_backend.get_*config_descriptor
implementations to return the actual length on success and uses this value as
the descriptor size in parse_configuration().

Note that the linux and wince backends were already returning the actual
length and thus are not touched.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>

5 files changed, 13 insertions, 10 deletions

diff --git a/libusb/descriptor.c b/libusb/descriptor.c
index 9047352..74d3365 100644
--- a/libusb/descriptor.c
+++ b/libusb/descriptor.c
@@ -338,17 +338,15 @@ static void clear_configuration(struct libusb_config_descriptor *config)
 
 static int parse_configuration(struct libusb_context *ctx,
 	struct libusb_config_descriptor *config, unsigned char *buffer,
-	int host_endian)
+	int size, int host_endian)
 {
 	int i;
 	int r;
-	int size;
 	size_t tmp;
 	struct usb_descriptor_header header;
 	struct libusb_interface *usb_interface;
 
 	usbi_parse_descriptor(buffer, "bbwbbbbb", config, host_endian);
-	size = config->wTotalLength;
 
 	if (config->bNumInterfaces > USB_MAXINTERFACES) {
 		usbi_err(ctx, "too many interfaces (%d)", config->bNumInterfaces);
@@ -521,7 +519,7 @@ int API_EXPORTED libusb_get_active_config_descriptor(libusb_device *dev,
 	if (r < 0)
 		goto err;
 
-	r = parse_configuration(dev->ctx, _config, buf, host_endian);
+	r = parse_configuration(dev->ctx, _config, buf, r, host_endian);
 	if (r < 0) {
 		usbi_err(dev->ctx, "parse_configuration failed with error %d", r);
 		goto err;
@@ -591,7 +589,7 @@ int API_EXPORTED libusb_get_config_descriptor(libusb_device *dev,
 	if (r < 0)
 		goto err;
 
-	r = parse_configuration(dev->ctx, _config, buf, host_endian);
+	r = parse_configuration(dev->ctx, _config, buf, r, host_endian);
 	if (r < 0) {
 		usbi_err(dev->ctx, "parse_configuration failed with error %d", r);
 		goto err;
diff --git a/libusb/os/darwin_usb.c b/libusb/os/darwin_usb.c
index 74e34cf..f9bd479 100644
--- a/libusb/os/darwin_usb.c
+++ b/libusb/os/darwin_usb.c
@@ -515,6 +515,7 @@ static int darwin_get_config_descriptor(struct libusb_device *dev, uint8_t confi
   struct darwin_device_priv *priv = (struct darwin_device_priv *)dev->os_priv;
   IOUSBConfigurationDescriptorPtr desc;
   IOReturn kresult;
+  int ret;
 
   if (!priv || !priv->device)
     return LIBUSB_ERROR_OTHER;
@@ -531,7 +532,11 @@ static int darwin_get_config_descriptor(struct libusb_device *dev, uint8_t confi
     *host_endian = 0;
   }
 
-  return darwin_to_libusb (kresult);
+  ret = darwin_to_libusb (kresult);
+  if (ret != LIBUSB_SUCCESS)
+    return ret;
+
+  return len;
 }
 
 /* check whether the os has configured the device */
diff --git a/libusb/os/openbsd_usb.c b/libusb/os/openbsd_usb.c
index 353385b..06aaff4 100644
--- a/libusb/os/openbsd_usb.c
+++ b/libusb/os/openbsd_usb.c
@@ -269,7 +269,7 @@ obsd_get_active_config_descriptor(struct libusb_device *dev,
 
 	*host_endian = 0;
 
-	return (LIBUSB_SUCCESS);
+	return len;
 }
 
 int
@@ -307,7 +307,7 @@ obsd_get_config_descriptor(struct libusb_device *dev, uint8_t idx,
 
 	*host_endian = 0;
 
-	return (LIBUSB_SUCCESS);
+	return len;
 }
 
 int
diff --git a/libusb/os/windows_usb.c b/libusb/os/windows_usb.c
index b07d193..061a0f8 100644
--- a/libusb/os/windows_usb.c
+++ b/libusb/os/windows_usb.c
@@ -1758,7 +1758,7 @@ static int windows_get_config_descriptor(struct libusb_device *dev, uint8_t conf
 	size = min(config_header->wTotalLength, len);
 	memcpy(buffer, priv->config_descriptor[config_index], size);
 
-	return LIBUSB_SUCCESS;
+	return size;
 }
 
 /*
diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index 0efafb3..8f8d647 100644
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 10709
+#define LIBUSB_NANO 10710