core: Introduce accessor functions for structure private data

The backend private data for the internal library structures has been
accessed through a zero-length os_priv array of type unsigned char.
This approach had two particular disadvantages:

  1) A special attribute was needed on the 'os_priv' member to ensure
     that the field was properly aligned to a natural pointer alignment.
     The support needed for this is not available in every compiler.

  2) Each access to the private data areas required an explicit cast
     from unsigned char to the type required by the backend.

This change reworks the way the private data is accessed by the
backends. New accessor functions return the private data as a void
pointer type, removing the need for an explicit cast (except for Haiku,
which is C++). The special alignment attribute trickery is also replaced
by simple pointer arithmetic.

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>

1 files changed, 24 insertions, 29 deletions

diff --git a/libusb/os/windows_common.c b/libusb/os/windows_common.c
index 3a11c56..4cf0cdf 100644
--- a/libusb/os/windows_common.c
+++ b/libusb/os/windows_common.c
@@ -100,11 +100,6 @@ const char *windows_error_str(DWORD error_code)
 }
 #endif
 
-static inline struct windows_context_priv *_context_priv(struct libusb_context *ctx)
-{
-	return (struct windows_context_priv *)ctx->os_priv;
-}
-
 /* Hash table functions - modified From glibc 2.3.2:
    [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
    [Knuth]            The Art of Computer Programming, part 3 (6.4)  */
@@ -402,7 +397,7 @@ static void get_windows_version(void)
 static void windows_transfer_callback(const struct windows_backend *backend,
 	struct usbi_transfer *itransfer, DWORD error, DWORD bytes_transferred)
 {
-	struct windows_transfer_priv *transfer_priv = get_transfer_priv(itransfer);
+	struct windows_transfer_priv *transfer_priv = usbi_get_transfer_priv(itransfer);
 	enum libusb_transfer_status status, istatus;
 
 	usbi_dbg("handling I/O completion with errcode %lu, length %lu",
@@ -456,7 +451,7 @@ static void windows_transfer_callback(const struct windows_backend *backend,
 
 static int windows_init(struct libusb_context *ctx)
 {
-	struct windows_context_priv *priv = _context_priv(ctx);
+	struct windows_context_priv *priv = usbi_get_context_priv(ctx);
 	char mutex_name[11 + 8 + 1]; // strlen("libusb_init") + (32-bit hex PID) + '\0'
 	HANDLE mutex;
 	int r = LIBUSB_ERROR_OTHER;
@@ -561,7 +556,7 @@ static void windows_exit(struct libusb_context *ctx)
 
 static int windows_set_option(struct libusb_context *ctx, enum libusb_option option, va_list ap)
 {
-	struct windows_context_priv *priv = _context_priv(ctx);
+	struct windows_context_priv *priv = usbi_get_context_priv(ctx);
 
 	UNUSED(ap);
 
@@ -582,26 +577,26 @@ static int windows_set_option(struct libusb_context *ctx, enum libusb_option opt
 
 static int windows_get_device_list(struct libusb_context *ctx, struct discovered_devs **discdevs)
 {
-	struct windows_context_priv *priv = _context_priv(ctx);
+	struct windows_context_priv *priv = usbi_get_context_priv(ctx);
 	return priv->backend->get_device_list(ctx, discdevs);
 }
 
 static int windows_open(struct libusb_device_handle *dev_handle)
 {
-	struct windows_context_priv *priv = _context_priv(HANDLE_CTX(dev_handle));
+	struct windows_context_priv *priv = usbi_get_context_priv(HANDLE_CTX(dev_handle));
 	return priv->backend->open(dev_handle);
 }
 
 static void windows_close(struct libusb_device_handle *dev_handle)
 {
-	struct windows_context_priv *priv = _context_priv(HANDLE_CTX(dev_handle));
+	struct windows_context_priv *priv = usbi_get_context_priv(HANDLE_CTX(dev_handle));
 	priv->backend->close(dev_handle);
 }
 
 static int windows_get_device_descriptor(struct libusb_device *dev,
 	unsigned char *buffer, int *host_endian)
 {
-	struct windows_context_priv *priv = _context_priv(DEVICE_CTX(dev));
+	struct windows_context_priv *priv = usbi_get_context_priv(DEVICE_CTX(dev));
 	*host_endian = 0;
 	return priv->backend->get_device_descriptor(dev, buffer);
 }
@@ -609,7 +604,7 @@ static int windows_get_device_descriptor(struct libusb_device *dev,
 static int windows_get_active_config_descriptor(struct libusb_device *dev,
 	unsigned char *buffer, size_t len, int *host_endian)
 {
-	struct windows_context_priv *priv = _context_priv(DEVICE_CTX(dev));
+	struct windows_context_priv *priv = usbi_get_context_priv(DEVICE_CTX(dev));
 	*host_endian = 0;
 	return priv->backend->get_active_config_descriptor(dev, buffer, len);
 }
@@ -617,7 +612,7 @@ static int windows_get_active_config_descriptor(struct libusb_device *dev,
 static int windows_get_config_descriptor(struct libusb_device *dev,
 	uint8_t config_index, unsigned char *buffer, size_t len, int *host_endian)
 {
-	struct windows_context_priv *priv = _context_priv(DEVICE_CTX(dev));
+	struct windows_context_priv *priv = usbi_get_context_priv(DEVICE_CTX(dev));
 	*host_endian = 0;
 	return priv->backend->get_config_descriptor(dev, config_index, buffer, len);
 }
@@ -625,57 +620,57 @@ static int windows_get_config_descriptor(struct libusb_device *dev,
 static int windows_get_config_descriptor_by_value(struct libusb_device *dev,
 	uint8_t bConfigurationValue, unsigned char **buffer, int *host_endian)
 {
-	struct windows_context_priv *priv = _context_priv(DEVICE_CTX(dev));
+	struct windows_context_priv *priv = usbi_get_context_priv(DEVICE_CTX(dev));
 	*host_endian = 0;
 	return priv->backend->get_config_descriptor_by_value(dev, bConfigurationValue, buffer);
 }
 
 static int windows_get_configuration(struct libusb_device_handle *dev_handle, int *config)
 {
-	struct windows_context_priv *priv = _context_priv(HANDLE_CTX(dev_handle));
+	struct windows_context_priv *priv = usbi_get_context_priv(HANDLE_CTX(dev_handle));
 	return priv->backend->get_configuration(dev_handle, config);
 }
 
 static int windows_set_configuration(struct libusb_device_handle *dev_handle, int config)
 {
-	struct windows_context_priv *priv = _context_priv(HANDLE_CTX(dev_handle));
+	struct windows_context_priv *priv = usbi_get_context_priv(HANDLE_CTX(dev_handle));
 	return priv->backend->set_configuration(dev_handle, config);
 }
 
 static int windows_claim_interface(struct libusb_device_handle *dev_handle, int interface_number)
 {
-	struct windows_context_priv *priv = _context_priv(HANDLE_CTX(dev_handle));
+	struct windows_context_priv *priv = usbi_get_context_priv(HANDLE_CTX(dev_handle));
 	return priv->backend->claim_interface(dev_handle, interface_number);
 }
 
 static int windows_release_interface(struct libusb_device_handle *dev_handle, int interface_number)
 {
-	struct windows_context_priv *priv = _context_priv(HANDLE_CTX(dev_handle));
+	struct windows_context_priv *priv = usbi_get_context_priv(HANDLE_CTX(dev_handle));
 	return priv->backend->release_interface(dev_handle, interface_number);
 }
 
 static int windows_set_interface_altsetting(struct libusb_device_handle *dev_handle,
 	int interface_number, int altsetting)
 {
-	struct windows_context_priv *priv = _context_priv(HANDLE_CTX(dev_handle));
+	struct windows_context_priv *priv = usbi_get_context_priv(HANDLE_CTX(dev_handle));
 	return priv->backend->set_interface_altsetting(dev_handle, interface_number, altsetting);
 }
 
 static int windows_clear_halt(struct libusb_device_handle *dev_handle, unsigned char endpoint)
 {
-	struct windows_context_priv *priv = _context_priv(HANDLE_CTX(dev_handle));
+	struct windows_context_priv *priv = usbi_get_context_priv(HANDLE_CTX(dev_handle));
 	return priv->backend->clear_halt(dev_handle, endpoint);
 }
 
 static int windows_reset_device(struct libusb_device_handle *dev_handle)
 {
-	struct windows_context_priv *priv = _context_priv(HANDLE_CTX(dev_handle));
+	struct windows_context_priv *priv = usbi_get_context_priv(HANDLE_CTX(dev_handle));
 	return priv->backend->reset_device(dev_handle);
 }
 
 static void windows_destroy_device(struct libusb_device *dev)
 {
-	struct windows_context_priv *priv = _context_priv(DEVICE_CTX(dev));
+	struct windows_context_priv *priv = usbi_get_context_priv(DEVICE_CTX(dev));
 	priv->backend->destroy_device(dev);
 }
 
@@ -683,8 +678,8 @@ static int windows_submit_transfer(struct usbi_transfer *itransfer)
 {
 	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
 	struct libusb_context *ctx = TRANSFER_CTX(transfer);
-	struct windows_context_priv *priv = _context_priv(ctx);
-	struct windows_transfer_priv *transfer_priv = get_transfer_priv(itransfer);
+	struct windows_context_priv *priv = usbi_get_context_priv(ctx);
+	struct windows_transfer_priv *transfer_priv = usbi_get_transfer_priv(itransfer);
 	short events;
 	int r;
 
@@ -749,8 +744,8 @@ static int windows_submit_transfer(struct usbi_transfer *itransfer)
 
 static int windows_cancel_transfer(struct usbi_transfer *itransfer)
 {
-	struct windows_context_priv *priv = _context_priv(ITRANSFER_CTX(itransfer));
-	struct windows_transfer_priv *transfer_priv = get_transfer_priv(itransfer);
+	struct windows_context_priv *priv = usbi_get_context_priv(ITRANSFER_CTX(itransfer));
+	struct windows_transfer_priv *transfer_priv = usbi_get_transfer_priv(itransfer);
 
 	// Try CancelIoEx() on the transfer
 	// If that fails, fall back to the backend's cancel_transfer()
@@ -769,7 +764,7 @@ static int windows_cancel_transfer(struct usbi_transfer *itransfer)
 
 static int windows_handle_events(struct libusb_context *ctx, struct pollfd *fds, usbi_nfds_t nfds, int num_ready)
 {
-	struct windows_context_priv *priv = _context_priv(ctx);
+	struct windows_context_priv *priv = usbi_get_context_priv(ctx);
 	struct usbi_transfer *itransfer;
 	struct windows_transfer_priv *transfer_priv;
 	DWORD result, bytes_transferred;
@@ -788,7 +783,7 @@ static int windows_handle_events(struct libusb_context *ctx, struct pollfd *fds,
 		transfer_priv = NULL;
 		usbi_mutex_lock(&ctx->flying_transfers_lock);
 		list_for_each_entry(itransfer, &ctx->flying_transfers, list, struct usbi_transfer) {
-			transfer_priv = get_transfer_priv(itransfer);
+			transfer_priv = usbi_get_transfer_priv(itransfer);
 			if (transfer_priv->pollable_fd.fd == fds[i].fd)
 				break;
 			transfer_priv = NULL;