io: make libuv more 64-bit safe

Continuation of jn/64-safe, for the required breaking changes to make
write_queue_size also safe internally for I/O on 32-bit machines.

Refs: #5076

docs/src/misc.rst

@@ -282,7 +282,7 @@ API
     .. warning:: Don't call libuv functions after calling
                  :c:func:`uv_library_shutdown()`.
 
-.. c:function:: uv_buf_t uv_buf_init(char* base, unsigned int len)
+.. c:function:: uv_buf_t uv_buf_init(char* base, size_t len)
 
     Constructor for :c:type:`uv_buf_t`.
 
@@ -290,6 +290,8 @@ API
     `base` and `len` members of the uv_buf_t struct. The user is responsible for
     freeing `base` after the uv_buf_t is done. Return struct passed by value.
 
+    .. versionchanged:: 2.0.0 `buf.len` is capped to INT32_MAX.
+
 .. c:function:: char** uv_setup_args(int argc, char** argv)
 
     Store the program arguments. Required for getting / setting the process title

docs/src/stream.rst

@@ -78,10 +78,12 @@ Data types
 Public members
 ^^^^^^^^^^^^^^
 
-.. c:member:: size_t uv_stream_t.write_queue_size
+.. c:member:: uint64_t uv_stream_t.write_queue_size
 
     Contains the amount of queued bytes waiting to be sent. Readonly.
 
+    .. versionchanged:: 2.0.0 Made uint64_t to avoid overflow.
+
 .. c:member:: uv_stream_t* uv_connect_t.handle
 
     Pointer to the stream where this connection request is running.
@@ -254,10 +256,11 @@ API
 
     .. versionchanged:: 1.4.0 UNIX implementation added.
 
-.. c:function:: size_t uv_stream_get_write_queue_size(const uv_stream_t* stream)
+.. c:function:: uint64_t uv_stream_get_write_queue_size(const uv_stream_t* stream)
 
     Returns `stream->write_queue_size`.
 
     .. versionadded:: 1.19.0
+    .. versionchanged:: 2.0.0 Return type made uint64_t
 
 .. seealso:: The :c:type:`uv_handle_t` API functions also apply.

include/uv.h

@@ -562,7 +562,7 @@ UV_EXTERN int uv_socketpair(int type,
 
 #define UV_STREAM_FIELDS                                                      \
   /* number of bytes queued for writing */                                    \
-  size_t write_queue_size;                                                    \
+  uint64_t write_queue_size;                                                  \
   uv_alloc_cb alloc_cb;                                                       \
   uv_read_cb read_cb;                                                         \
   /* private */                                                               \
@@ -580,7 +580,7 @@ struct uv_stream_s {
   UV_STREAM_FIELDS
 };
 
-UV_EXTERN size_t uv_stream_get_write_queue_size(const uv_stream_t* stream);
+UV_EXTERN uint64_t uv_stream_get_write_queue_size(const uv_stream_t* stream);
 
 UV_EXTERN int uv_listen(uv_stream_t* stream, int backlog, uv_connection_cb cb);
 UV_EXTERN int uv_accept(uv_stream_t* server, uv_stream_t* client);

src/uv-common.c

@@ -191,7 +191,7 @@ size_t uv_loop_size(void) {
 uv_buf_t uv_buf_init(char* base, size_t len) {
   uv_buf_t buf;
   buf.base = base;
-  buf.len = len;
+  buf.len = len > INT32_MAX ? INT32_MAX : len;
   return buf;
 }
 

src/uv-data-getter-setters.c

@@ -78,7 +78,7 @@ void uv_req_set_data(uv_req_t* req, void* data) {
   req->data = data;
 }
 
-size_t uv_stream_get_write_queue_size(const uv_stream_t* stream) {
+uint64_t uv_stream_get_write_queue_size(const uv_stream_t* stream) {
   return stream->write_queue_size;
 }
 

test/test-buf.c

@@ -18,21 +18,29 @@
 
 #include <stdint.h>
 
+
 TEST_IMPL(buf_large) {
   uv_buf_t buf;
 
   buf = uv_buf_init(NULL, SIZE_MAX);
+  ASSERT(buf.len == INT32_MAX);
+
 #ifdef _WIN32
   WSABUF* wbuf;
 
   wbuf = (WSABUF*) &buf;
   ASSERT(wbuf->len == buf.len);
+  ASSERT(sizeof(uv_buf_t) == sizeof(WSABUF));
+  ASSERT(sizeof(((uv_buf_t*) 0)->base) ==
+         sizeof(((WSABUF*) 0)->buf));
+  ASSERT(sizeof(((uv_buf_t*) 0)->len) == sizeof(((WSABUF*) 0)->len));
+  ASSERT(offsetof(uv_buf_t, base) == offsetof(WSABUF, buf));
+  ASSERT(offsetof(uv_buf_t, len) == offsetof(WSABUF, len));
 #else
   struct iovec* iobuf;
 
   iobuf = (struct iovec*) &buf;
   ASSERT(iobuf->iov_len == buf.len);
-  ASSERT(buf.len == SIZE_MAX);
 
   /* Verify that uv_buf_t is ABI-compatible with struct iovec. */
   ASSERT(sizeof(uv_buf_t) == sizeof(struct iovec));