* Number of bytes actually copied will be returned, which is
* min(bytes, iov_size(iov)-offset)
* `Offset' must point to the inside of iovec.
- * It is okay to use very large value for `bytes' since we're
- * limited by the size of the iovec anyway, provided that the
- * buffer pointed to by buf has enough space. One possible
- * such "large" value is -1 (sinice size_t is unsigned),
- * so specifying `-1' as `bytes' means 'up to the end of iovec'.
*/
size_t iov_from_buf_full(const struct iovec *iov, unsigned int iov_cnt,
size_t offset, const void *buf, size_t bytes);
size_t iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt,
- size_t offset, void *buf, size_t bytes);
+ size_t offset, void *buf, size_t bytes);
static inline size_t
iov_from_buf(const struct iovec *iov, unsigned int iov_cnt,
* up to the end of it, will be filled with the specified value.
* Function return actual number of bytes processed, which is
* min(size, iov_size(iov) - offset).
- * Again, it is okay to use large value for `bytes' to mean "up to the end".
*/
size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt,
size_t offset, int fillc, size_t bytes);
size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt,
size_t bytes);
+/* Information needed to undo an iov_discard_*() operation */
+typedef struct {
+ struct iovec *modified_iov;
+ struct iovec orig;
+} IOVDiscardUndo;
+
+/*
+ * Undo an iov_discard_front_undoable() or iov_discard_back_undoable()
+ * operation. If multiple operations are made then each one needs a separate
+ * IOVDiscardUndo and iov_discard_undo() must be called in the reverse order
+ * that the operations were made.
+ */
+void iov_discard_undo(IOVDiscardUndo *undo);
+
+/*
+ * Undoable versions of iov_discard_front() and iov_discard_back(). Use
+ * iov_discard_undo() to reset to the state before the discard operations.
+ */
+size_t iov_discard_front_undoable(struct iovec **iov, unsigned int *iov_cnt,
+ size_t bytes, IOVDiscardUndo *undo);
+size_t iov_discard_back_undoable(struct iovec *iov, unsigned int *iov_cnt,
+ size_t bytes, IOVDiscardUndo *undo);
+
typedef struct QEMUIOVector {
struct iovec *iov;
int niov;
- int nalloc;
- size_t size;
+
+ /*
+ * For external @iov (qemu_iovec_init_external()) or allocated @iov
+ * (qemu_iovec_init()), @size is the cumulative size of iovecs and
+ * @local_iov is invalid and unused.
+ *
+ * For embedded @iov (QEMU_IOVEC_INIT_BUF() or qemu_iovec_init_buf()),
+ * @iov is equal to &@local_iov, and @size is valid, as it has same
+ * offset and type as @local_iov.iov_len, which is guaranteed by
+ * static assertion below.
+ *
+ * @nalloc is always valid and is -1 both for embedded and external
+ * cases. It is included in the union only to ensure the padding prior
+ * to the @size field will not result in a 0-length array.
+ */
+ union {
+ struct {
+ int nalloc;
+ struct iovec local_iov;
+ };
+ struct {
+ char __pad[sizeof(int) + offsetof(struct iovec, iov_len)];
+ size_t size;
+ };
+ };
} QEMUIOVector;
+QEMU_BUILD_BUG_ON(offsetof(QEMUIOVector, size) !=
+ offsetof(QEMUIOVector, local_iov.iov_len));
+
+#define QEMU_IOVEC_INIT_BUF(self, buf, len) \
+{ \
+ .iov = &(self).local_iov, \
+ .niov = 1, \
+ .nalloc = -1, \
+ .local_iov = { \
+ .iov_base = (void *)(buf), /* cast away const */ \
+ .iov_len = (len), \
+ }, \
+}
+
+/*
+ * qemu_iovec_init_buf
+ *
+ * Initialize embedded QEMUIOVector.
+ *
+ * Note: "const" is used over @buf pointer to make it simple to pass
+ * const pointers, appearing in read functions. Then this "const" is
+ * cast away by QEMU_IOVEC_INIT_BUF().
+ */
+static inline void qemu_iovec_init_buf(QEMUIOVector *qiov,
+ const void *buf, size_t len)
+{
+ *qiov = (QEMUIOVector) QEMU_IOVEC_INIT_BUF(*qiov, buf, len);
+}
+
+static inline void *qemu_iovec_buf(QEMUIOVector *qiov)
+{
+ /* Only supports embedded iov */
+ assert(qiov->nalloc == -1 && qiov->iov == &qiov->local_iov);
+
+ return qiov->local_iov.iov_base;
+}
+
void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint);
void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov);
+int qemu_iovec_init_extended(
+ QEMUIOVector *qiov,
+ void *head_buf, size_t head_len,
+ QEMUIOVector *mid_qiov, size_t mid_offset, size_t mid_len,
+ void *tail_buf, size_t tail_len);
+void qemu_iovec_init_slice(QEMUIOVector *qiov, QEMUIOVector *source,
+ size_t offset, size_t len);
+int qemu_iovec_subvec_niov(QEMUIOVector *qiov, size_t offset, size_t len);
void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len);
void qemu_iovec_concat(QEMUIOVector *dst,
QEMUIOVector *src, size_t soffset, size_t sbytes);
size_t qemu_iovec_concat_iov(QEMUIOVector *dst,
struct iovec *src_iov, unsigned int src_cnt,
size_t soffset, size_t sbytes);
-bool qemu_iovec_is_zero(QEMUIOVector *qiov);
+bool qemu_iovec_is_zero(QEMUIOVector *qiov, size_t qiov_offeset, size_t bytes);
void qemu_iovec_destroy(QEMUIOVector *qiov);
void qemu_iovec_reset(QEMUIOVector *qiov);
size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset,
projects / qemu.git / blobdiff