From d336336c8164859e4527cbb9f3df189f8bb406de Mon Sep 17 00:00:00 2001
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Mon, 24 Sep 2012 13:02:52 +0200
Subject: iov: add iov_cpy

Add API to copy part of iovec safely.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 iov.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

(limited to 'iov.c')

diff --git a/iov.c b/iov.c
index c6a66f0afe..b7378bf7ce 100644
--- a/iov.c
+++ b/iov.c
@@ -228,3 +228,26 @@ void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
         fprintf(fp, "\n");
     }
 }
+
+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)
+{
+    size_t len;
+    unsigned int i, j;
+    for (i = 0, j = 0; i < iov_cnt && j < dst_iov_cnt && bytes; i++) {
+        if (offset >= iov[i].iov_len) {
+            offset -= iov[i].iov_len;
+            continue;
+        }
+        len = MIN(bytes, iov[i].iov_len - offset);
+
+        dst_iov[j].iov_base = iov[i].iov_base + offset;
+        dst_iov[j].iov_len = len;
+        j++;
+        bytes -= len;
+        offset = 0;
+    }
+    assert(offset == 0);
+    return j;
+}
-- 
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