Merge remote-tracking branch 'mjt/mjt-iov2' into staging

* mjt/mjt-iov2:
  rewrite iov_send_recv() and move it to iov.c
  cleanup qemu_co_sendv(), qemu_co_recvv() and friends
  export iov_send_recv() and use it in iov_send() and iov_recv()
  rename qemu_sendv to iov_send, change proto and move declarations to iov.h
  change qemu_iovec_to_buf() to match other to,from_buf functions
  consolidate qemu_iovec_copy() and qemu_iovec_concat() and make them consistent
  allow qemu_iovec_from_buffer() to specify offset from which to start copying
  consolidate qemu_iovec_memset{,_skip}() into single function and use existing iov_memset()
  rewrite iov_* functions
  change iov_* function prototypes to be more appropriate
  virtio-serial-bus: use correct lengths in control_out() message

Conflicts:
	tests/Makefile

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 71 insertions, 6 deletions

diff --git a/iov.h b/iov.h
index 94d2f78284..381f37a546 100644
--- a/iov.h
+++ b/iov.h
@@ -1,10 +1,11 @@
 /*
- * Helpers for getting linearized buffers from iov / filling buffers into iovs
+ * Helpers for using (partial) iovecs.
  *
  * Copyright (C) 2010 Red Hat, Inc.
  *
  * Author(s):
  *  Amit Shah <amit.shah@redhat.com>
+ *  Michael Tokarev <mjt@tls.msk.ru>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
@@ -12,12 +13,76 @@
 
 #include "qemu-common.h"
 
+/**
+ * count and return data size, in bytes, of an iovec
+ * starting at `iov' of `iov_cnt' number of elements.
+ */
+size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt);
+
+/**
+ * Copy from single continuous buffer to scatter-gather vector of buffers
+ * (iovec) and back like memcpy() between two continuous memory regions.
+ * Data in single continuous buffer starting at address `buf' and
+ * `bytes' bytes long will be copied to/from an iovec `iov' with
+ * `iov_cnt' number of elements, starting at byte position `offset'
+ * within the iovec.  If the iovec does not contain enough space,
+ * only part of data will be copied, up to the end of the iovec.
+ * 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(struct iovec *iov, unsigned int iov_cnt,
-                    const void *buf, size_t iov_off, size_t size);
+                    size_t offset, const void *buf, size_t bytes);
 size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
-                  void *buf, size_t iov_off, size_t size);
-size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt);
-size_t iov_clear(const struct iovec *iov, const unsigned int iov_cnt,
-                 size_t iov_off, size_t size);
+                  size_t offset, void *buf, size_t bytes);
+
+/**
+ * Set data bytes pointed out by iovec `iov' of size `iov_cnt' elements,
+ * starting at byte offset `start', to value `fillc', repeating it
+ * `bytes' number of times.  `Offset' must point to the inside of iovec.
+ * If `bytes' is large enough, only last bytes portion of iovec,
+ * 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);
+
+/*
+ * Send/recv data from/to iovec buffers directly
+ *
+ * `offset' bytes in the beginning of iovec buffer are skipped and
+ * next `bytes' bytes are used, which must be within data of iovec.
+ *
+ *   r = iov_send_recv(sockfd, iov, iovcnt, offset, bytes, true);
+ *
+ * is logically equivalent to
+ *
+ *   char *buf = malloc(bytes);
+ *   iov_to_buf(iov, iovcnt, offset, buf, bytes);
+ *   r = send(sockfd, buf, bytes, 0);
+ *   free(buf);
+ *
+ * For iov_send_recv() _whole_ area being sent or received
+ * should be within the iovec, not only beginning of it.
+ */
+ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt,
+                      size_t offset, size_t bytes, bool do_send);
+#define iov_recv(sockfd, iov, iov_cnt, offset, bytes) \
+  iov_send_recv(sockfd, iov, iov_cnt, offset, bytes, false)
+#define iov_send(sockfd, iov, iov_cnt, offset, bytes) \
+  iov_send_recv(sockfd, iov, iov_cnt, offset, bytes, true)
+
+/**
+ * Produce a text hexdump of iovec `iov' with `iov_cnt' number of elements
+ * in file `fp', prefixing each line with `prefix' and processing not more
+ * than `limit' data bytes.
+ */
 void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
                  FILE *fp, const char *prefix, size_t limit);