[Qemu-devel] [PATCH V7 2/6] Adding utility function iov_net_csum_add() for iovec checksum calculation Adding utility function iov_rebuild() for smart iovec copy

[Dmitry Fleytman <dmitry@daynix.com>]

Signed-off-by: Dmitry Fleytman <dmitry@daynix.com>
Signed-off-by: Yan Vugenfirer <yan@daynix.com>
---
 Makefile.objs  |  1 +
 iov.c          | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 iov.h          | 13 +++++++++++++
 tests/Makefile |  2 +-
 4 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/Makefile.objs b/Makefile.objs
index 593a592..5400c6c 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -43,6 +43,7 @@ coroutine-obj-$(CONFIG_WIN32) += coroutine-win32.o
 
 block-obj-y = iov.o cache-utils.o qemu-option.o module.o async.o
 block-obj-y += nbd.o block.o blockjob.o aes.o qemu-config.o
+block-obj-y += net/checksum.o
 block-obj-y += thread-pool.o qemu-progress.o qemu-sockets.o uri.o notify.o
 block-obj-y += $(coroutine-obj-y) $(qobject-obj-y) $(version-obj-y)
 block-obj-$(CONFIG_POSIX) += event_notifier-posix.o aio-posix.o
diff --git a/iov.c b/iov.c
index a81eedc..c9fd128 100644
--- a/iov.c
+++ b/iov.c
@@ -17,6 +17,7 @@
  */
 
 #include "iov.h"
+#include "net/checksum.h"
 
 #ifdef _WIN32
 # include <windows.h>
@@ -252,6 +253,58 @@ unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt,
     return j;
 }
 
+size_t iov_rebuild(struct iovec *dst, unsigned int dst_cnt,
+                   const struct iovec *src, const unsigned int src_cnt,
+                   size_t src_off)
+{
+    size_t curr_src_off = 0;
+    unsigned int i, j = 0;
+
+    for (i = 0; i < src_cnt; i++) {
+        if (src_off < (curr_src_off + src[i].iov_len)) {
+            if (j == dst_cnt) {
+                return (size_t) -1;
+            }
+
+            dst[j].iov_len = curr_src_off + src[i].iov_len - src_off;
+            dst[j].iov_base = src[i].iov_base + (src_off - curr_src_off);
+
+            src_off += dst[j].iov_len;
+            j++;
+        }
+        curr_src_off += src[i].iov_len;
+    }
+    return j;
+}
+
+uint32_t
+iov_net_csum_add(const struct iovec *iov, const unsigned int iov_cnt,
+                 size_t iov_off, size_t size)
+{
+    size_t iovec_off, buf_off;
+    unsigned int i;
+    uint32_t res = 0;
+    uint32_t seq = 0;
+
+    iovec_off = 0;
+    buf_off = 0;
+    for (i = 0; i < iov_cnt && size; i++) {
+        if (iov_off < (iovec_off + iov[i].iov_len)) {
+            size_t len = MIN((iovec_off + iov[i].iov_len) - iov_off , size);
+            void *chunk_buf = iov[i].iov_base + (iov_off - iovec_off);
+
+            res += net_checksum_add_cont(len, chunk_buf, seq);
+            seq += len;
+
+            buf_off += len;
+            iov_off += len;
+            size -= len;
+        }
+        iovec_off += iov[i].iov_len;
+    }
+    return res;
+}
+
 /* io vectors */
 
 void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint)
diff --git a/iov.h b/iov.h
index 34c8ec9..9439eb7 100644
--- a/iov.h
+++ b/iov.h
@@ -95,3 +95,16 @@ void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
 unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt,
                  const struct iovec *iov, unsigned int iov_cnt,
                  size_t offset, size_t bytes);
+
+/**
+ * Copy data between scatter-gather vectors
+ */
+size_t iov_rebuild(struct iovec *dest, unsigned int dest_cnt,
+                   const struct iovec *src, const unsigned int src_cnt,
+                   size_t src_off);
+
+/**
+ * Checksum calculation for scatter-gather vector
+ */
+uint32_t iov_net_csum_add(const struct iovec *iov, const unsigned int iov_cnt,
+                          size_t iov_off, size_t size);
diff --git a/tests/Makefile b/tests/Makefile
index 9bf0765..8fb5241 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -49,7 +49,7 @@ tests/check-qlist$(EXESUF): tests/check-qlist.o qlist.o qint.o
 tests/check-qfloat$(EXESUF): tests/check-qfloat.o qfloat.o
 tests/check-qjson$(EXESUF): tests/check-qjson.o $(qobject-obj-y) qemu-tool.o
 tests/test-coroutine$(EXESUF): tests/test-coroutine.o $(coroutine-obj-y) $(tools-obj-y) $(block-obj-y) iov.o
-tests/test-iov$(EXESUF): tests/test-iov.o iov.o
+tests/test-iov$(EXESUF): tests/test-iov.o iov.o net/checksum.o
 
 tests/test-qapi-types.c tests/test-qapi-types.h :\
 $(SRC_PATH)/qapi-schema-test.json $(SRC_PATH)/scripts/qapi-types.py
-- 
1.7.11.7