iovec: initial implementation

kernel-src/include/kernel/iovec.h

@@ -0,0 +1,67 @@
+#ifndef _IOVEC_H
+#define _IOVEC_H
+
+#include <stddef.h>
+#include <stdbool.h>
+#include <ringbuffer.h>
+
+typedef struct {
+	void *addr;
+	size_t len;
+} iovec_t;
+
+typedef struct {
+	iovec_t *iovec;
+	size_t count;
+
+	iovec_t *current;
+	uintmax_t current_offset;
+
+	uintmax_t total_offset;
+	size_t total_size;
+} iovec_iterator_t;
+
+// checks if all iovec[x].addr is an userspace address
+bool iovec_user_check(iovec_t *iovec, size_t count);
+
+// returns the sum of the size of all iovecs
+size_t iovec_size(iovec_t *iovec, size_t count);
+
+// initializes an iovec iterator
+void iovec_iterator_init(iovec_iterator_t *iovec_iterator, iovec_t *iovec, size_t count);
+
+// skips skip_count bytes in the iovec iterator, returns the remaining number of bytes
+size_t iovec_iterator_skip(iovec_iterator_t *iovec_iterator, size_t skip_count);
+
+// sets the current offset of the iovec iterator to offset, returns the remaining number of bytes
+size_t iovec_iterator_set(iovec_iterator_t *iovec_iterator, size_t offset);
+
+// copies byte_count bytes from the iovec_iterator into buffer
+// NOTE: the iovec can have userspace addresses. in this case, the copy can possibly fail with EFAULT
+int iovec_iterator_copy_to_buffer(iovec_iterator_t *iovec_iterator, void *buffer, size_t byte_count);
+
+// copies byte_count bytes from buffer into the iovec_iterator
+// NOTE: the iovec can have userspace addresses. in this case, the copy can possibly fail with EFAULT
+int iovec_iterator_copy_from_buffer(iovec_iterator_t *iovec_iterator, void *buffer, size_t byte_count);
+
+// copies byte_count bytes from the iovec_iterator into the ringbuffer
+// returns the number of bytes copied
+// NOTE: the iovec can have userspace addresses. in this case, the copy can possibly fail by returning RINGBUFFER_USER_COPY_FAILED
+size_t iovec_iterator_copy_to_ringbuffer(iovec_iterator_t *iovec_iterator, ringbuffer_t *ringbuffer, size_t byte_count);
+
+// copies byte_count bytes from the ringbuffer into the iovec_iterator
+// returns the number of bytes copied
+// NOTE: the iovec can have userspace addresses. in this case, the copy can possibly fail with RINGBUFFER_USER_COPY_FAILED
+size_t iovec_iterator_copy_from_ringbuffer(iovec_iterator_t *iovec_iterator, ringbuffer_t *ringbuffer, size_t byte_count);
+
+// copies byte_count bytes from the ringbuffer into the iovec_iterator, without moving the ringbuffer read pointer
+// returns the number of bytes copied
+// NOTE: the iovec can have userspace addresses. in this case, the copy can possibly fail with RINGBUFFER_USER_COPY_FAILED
+size_t iovec_iterator_peek_from_ringbuffer(iovec_iterator_t *iovec_iterator, ringbuffer_t *ringbuffer, size_t byte_count, uintmax_t ringbuffer_offset);
+
+// returns the physical address of the next page in the iovec_iterator, adding a reference count while at it
+// fails with EINVAL if the iterator does not currently point to the start of a page or there is not enough space for a page
+// fails with EFAULT if the page is not mapped
+int iovec_iterator_next_page(iovec_iterator_t *iovec_iterator, void **page);
+
+#endif