change iov_* function prototypes to be more appropriate

Reorder arguments to be more natural, readable and
consistent with other iov_* functions, and change
argument names, from:
 iov_from_buf(iov, iov_cnt, buf, iov_off, size)
to
 iov_from_buf(iov, iov_cnt, offset, buf, bytes)

The result becomes natural English:

 copy data to this `iov' vector with `iov_cnt'
 elements starting at byte offset `offset'
 from memory buffer `buf', processing `bytes'
 bytes max.

(Try to read the original prototype this way).

Also change iov_clear() to more general iov_memset()
(it uses memset() internally anyway).

While at it, add comments to the header file
describing what the routines actually does.

The patch only renames argumens in the header, but
keeps old names in the implementation.  The next
patch will touch actual code to match.

Now, it might look wrong to pay so much attention
to so small things.  But we've so many badly designed
interfaces already so the whole thing becomes rather
confusing or error prone.  One example of this is
previous commit and small discussion which emerged
from it, with an outcome that the utility functions
like these aren't well-understdandable, leading to
strange usage cases.  That's why I paid quite some
attention to this set of functions and a few
others in subsequent patches.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

5 files changed, 11 insertions, 11 deletions

diff --git a/hw/rtl8139.c b/hw/rtl8139.c
index eb22d04fad..8128b64a0f 100644
--- a/hw/rtl8139.c
+++ b/hw/rtl8139.c
@@ -1783,7 +1783,7 @@ static void rtl8139_transfer_frame(RTL8139State *s, uint8_t *buf, int size,
         if (iov) {
             buf2_size = iov_size(iov, 3);
             buf2 = g_malloc(buf2_size);
-            iov_to_buf(iov, 3, buf2, 0, buf2_size);
+            iov_to_buf(iov, 3, 0, buf2, buf2_size);
             buf = buf2;
         }
 
diff --git a/hw/usb/core.c b/hw/usb/core.c
index 0e02da7601..2641685a32 100644
--- a/hw/usb/core.c
+++ b/hw/usb/core.c
@@ -522,10 +522,10 @@ void usb_packet_copy(USBPacket *p, void *ptr, size_t bytes)
     switch (p->pid) {
     case USB_TOKEN_SETUP:
     case USB_TOKEN_OUT:
-        iov_to_buf(p->iov.iov, p->iov.niov, ptr, p->result, bytes);
+        iov_to_buf(p->iov.iov, p->iov.niov, p->result, ptr, bytes);
         break;
     case USB_TOKEN_IN:
-        iov_from_buf(p->iov.iov, p->iov.niov, ptr, p->result, bytes);
+        iov_from_buf(p->iov.iov, p->iov.niov, p->result, ptr, bytes);
         break;
     default:
         fprintf(stderr, "%s: invalid pid: %x\n", __func__, p->pid);
@@ -539,7 +539,7 @@ void usb_packet_skip(USBPacket *p, size_t bytes)
     assert(p->result >= 0);
     assert(p->result + bytes <= p->iov.size);
     if (p->pid == USB_TOKEN_IN) {
-        iov_clear(p->iov.iov, p->iov.niov, p->result, bytes);
+        iov_memset(p->iov.iov, p->iov.niov, p->result, 0, bytes);
     }
     p->result += bytes;
 }
diff --git a/hw/virtio-balloon.c b/hw/virtio-balloon.c
index 075ed87e37..23effa40a0 100644
--- a/hw/virtio-balloon.c
+++ b/hw/virtio-balloon.c
@@ -77,7 +77,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
         size_t offset = 0;
         uint32_t pfn;
 
-        while (iov_to_buf(elem.out_sg, elem.out_num, &pfn, offset, 4) == 4) {
+        while (iov_to_buf(elem.out_sg, elem.out_num, offset, &pfn, 4) == 4) {
             ram_addr_t pa;
             ram_addr_t addr;
 
@@ -118,7 +118,7 @@ static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
      */
     reset_stats(s);
 
-    while (iov_to_buf(elem->out_sg, elem->out_num, &stat, offset, sizeof(stat))
+    while (iov_to_buf(elem->out_sg, elem->out_num, offset, &stat, sizeof(stat))
            == sizeof(stat)) {
         uint16_t tag = tswap16(stat.tag);
         uint64_t val = tswap64(stat.val);
diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 3f190d417e..533aa3d0f3 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -656,8 +656,8 @@ static ssize_t virtio_net_receive(VLANClientState *nc, const uint8_t *buf, size_
         }
 
         /* copy in packet.  ugh */
-        len = iov_from_buf(sg, elem.in_num,
-                           buf + offset, 0, size - offset);
+        len = iov_from_buf(sg, elem.in_num, 0,
+                           buf + offset, size - offset);
         total += len;
         offset += len;
         /* If buffers can't be merged, at this point we
diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
index 1e477e5a33..728f218dcf 100644
--- a/hw/virtio-serial-bus.c
+++ b/hw/virtio-serial-bus.c
@@ -106,8 +106,8 @@ static size_t write_to_port(VirtIOSerialPort *port,
             break;
         }
 
-        len = iov_from_buf(elem.in_sg, elem.in_num,
-                           buf + offset, 0, size - offset);
+        len = iov_from_buf(elem.in_sg, elem.in_num, 0,
+                           buf + offset, size - offset);
         offset += len;
 
         virtqueue_push(vq, &elem, len);
@@ -467,7 +467,7 @@ static void control_out(VirtIODevice *vdev, VirtQueue *vq)
             buf = g_malloc(cur_len);
             len = cur_len;
         }
-        iov_to_buf(elem.out_sg, elem.out_num, buf, 0, cur_len);
+        iov_to_buf(elem.out_sg, elem.out_num, 0, buf, cur_len);
 
         handle_control_message(vser, buf, cur_len);
         virtqueue_push(vq, &elem, 0);