refactor: flatten http buffers

runtime/include/current_sandbox_send_response.h

@@ -25,7 +25,7 @@ current_sandbox_send_response()
 {
 	struct sandbox *sandbox = current_sandbox_get();
 	assert(sandbox != NULL);
-	struct vec_u8 *response = sandbox->response;
+	struct vec_u8 *response = &sandbox->response;
 	assert(response != NULL);
 
 	int rc;

runtime/include/sandbox_functions.h

@@ -48,12 +48,8 @@ static inline void
 sandbox_free_http_buffers(struct sandbox *sandbox)
 {
 	assert(sandbox);
-	assert(sandbox->request);
-	assert(sandbox->response);
-	vec_u8_free(sandbox->request);
-	vec_u8_free(sandbox->response);
-	sandbox->request  = NULL;
-	sandbox->response = NULL;
+	vec_u8_deinit(&sandbox->request);
+	vec_u8_deinit(&sandbox->response);
 }
 
 /**

runtime/include/sandbox_receive_request.h

@@ -27,7 +27,7 @@ sandbox_receive_request(struct sandbox *sandbox)
 
 	int rc = 0;
 
-	struct vec_u8 *request = sandbox->request;
+	struct vec_u8 *request = &sandbox->request;
 	assert(request->length == 0);
 	assert(request->capacity > 0);
 

runtime/include/sandbox_types.h

@@ -50,8 +50,8 @@ struct sandbox {
 	int                 client_socket_descriptor;
 	http_parser         http_parser;
 	struct http_request http_request;
-	struct vec_u8 *     request;
-	struct vec_u8 *     response;
+	struct vec_u8       request;
+	struct vec_u8       response;
 
 	/* WebAssembly Module State */
 	struct module *module; /* the module this is an instance of */

runtime/include/vec_u8.h

@@ -4,34 +4,108 @@
 #include <stdlib.h>
 
 struct vec_u8 {
-	size_t  length;
-	size_t  capacity;
-	uint8_t buffer[];
+	size_t   length;
+	size_t   capacity;
+	uint8_t *buffer;
 };
 
+static inline struct vec_u8 *vec_u8_alloc(void);
+static inline int            vec_u8_init(struct vec_u8 *self, size_t capacity);
+static inline struct vec_u8 *vec_u8_new(size_t capacity);
+static inline void           vec_u8_deinit(struct vec_u8 *self);
+static inline void           vec_u8_free(struct vec_u8 *self);
+static inline void           vec_u8_delete(struct vec_u8 *self);
+
+/**
+ * Allocates an uninitialized vec on the heap'
+ * @returns a pointer to an uninitialized vec on the heap
+ */
 static inline struct vec_u8 *
-vec_u8_alloc(size_t capacity)
+vec_u8_alloc(void)
 {
-	return (struct vec_u8 *)calloc(1, sizeof(struct vec_u8) + capacity * sizeof(uint8_t));
+	return (struct vec_u8 *)calloc(1, sizeof(struct vec_u8));
 }
 
-static inline void
+/**
+ * Initializes a vec, allocating a backing buffer for the provided capcity
+ * @param self pointer to an uninitialized vec
+ * @param capacity
+ * @returns 0 on success, -1 on failure
+ */
+static inline int
 vec_u8_init(struct vec_u8 *self, size_t capacity)
 {
+	if (capacity == 0) {
+		self->buffer = NULL;
+	} else {
+		self->buffer = calloc(capacity, sizeof(uint8_t));
+		if (self->buffer == NULL) return -1;
+	}
+
 	self->length   = 0;
 	self->capacity = capacity;
+
+	return 0;
 }
 
+/**
+ * Allocate and initialize a vec with a backing buffer
+ * @param capacity
+ * @returns a pointer to an initialized vec on the heap, ready for use
+ */
 static inline struct vec_u8 *
 vec_u8_new(size_t capacity)
 {
-	struct vec_u8 *self = vec_u8_alloc(capacity);
-	vec_u8_init(self, capacity);
+	struct vec_u8 *self = vec_u8_alloc();
+	if (self == NULL) return self;
+
+	int rc = vec_u8_init(self, capacity);
+	if (rc < 0) {
+		vec_u8_free(self);
+		return NULL;
+	}
+
 	return self;
 }
 
+/**
+ * Deinitialize a vec, clearing out members and releasing the backing buffer
+ * @param self
+ */
+static inline void
+vec_u8_deinit(struct vec_u8 *self)
+{
+	if (self->capacity == 0) {
+		assert(self->buffer == NULL);
+		assert(self->length == 0);
+	}
+
+	free(self->buffer);
+	self->buffer   = NULL;
+	self->length   = 0;
+	self->capacity = 0;
+}
+
+/**
+ * Frees a vec struct allocated on the heap
+ * Assumes that the vec has already been deinitialized
+ */
 static inline void
 vec_u8_free(struct vec_u8 *self)
 {
+	assert(self->buffer == NULL);
+	assert(self->length == 0);
+	assert(self->capacity == 0);
 	free(self);
 }
+
+/**
+ * Deinitializes and frees a vec allocated to the heap
+ * @param self
+ */
+static inline void
+vec_u8_delete(struct vec_u8 *self)
+{
+	vec_u8_deinit(self);
+	vec_u8_free(self);
+}

runtime/src/libc/syscall.c

@@ -135,18 +135,19 @@ wasm_read(int32_t filedes, int32_t buf_offset, int32_t nbyte)
 int32_t
 wasm_write(int32_t fd, int32_t buf_offset, int32_t buf_size)
 {
-	struct sandbox *s      = current_sandbox_get();
-	char *          buffer = current_sandbox_get_ptr_void(buf_offset, buf_size);
+	struct sandbox *s        = current_sandbox_get();
+	char *          buffer   = current_sandbox_get_ptr_void(buf_offset, buf_size);
+	struct vec_u8 * response = &s->response;
 
 	if (fd == STDERR_FILENO) { write(STDERR_FILENO, buffer, buf_size); }
 
 	if (fd == STDOUT_FILENO) {
-		int buffer_remaining = s->response->capacity - s->response->length;
+		int buffer_remaining = response->capacity - response->length;
 		int to_write         = buffer_remaining > buf_size ? buf_size : buffer_remaining;
 
 		if (to_write == 0) return 0;
-		memcpy(&s->response->buffer[s->response->length], buffer, to_write);
-		s->response->length += to_write;
+		memcpy(&response->buffer[response->length], buffer, to_write);
+		response->length += to_write;
 
 		return to_write;
 	}

runtime/src/sandbox.c

@@ -74,12 +74,13 @@ sandbox_free_stack(struct sandbox *sandbox)
 static inline int
 sandbox_allocate_http_buffers(struct sandbox *self)
 {
-	self->request = vec_u8_new(self->module->max_request_size);
-	if (self->request == NULL) return -1;
+	int rc;
+	rc = vec_u8_init(&self->request, self->module->max_request_size);
+	if (rc < 0) return -1;
 
-	self->response = vec_u8_new(self->module->max_response_size);
-	if (self->response == NULL) {
-		vec_u8_free(self->request);
+	rc = vec_u8_init(&self->response, self->module->max_response_size);
+	if (rc < 0) {
+		vec_u8_deinit(&self->request);
 		return -1;
 	}