rename qemu_sendv to iov_send, change proto and move declarations to iov.h

Rename arguments and use size_t for sizes instead of int,
from
 int
 qemu_sendv(int sockfd, struct iovec *iov,
            int len, int iov_offset)
to
 ssize_t
 iov_send(int sockfd, struct iovec *iov,
          size_t offset, size_t bytes)

The main motivation was to make it clear that length
and offset are in _bytes_, not in iov elements: it was
very confusing before, because all standard functions
which deals with iovecs expects number of iovs, not
bytes, even the fact that struct iovec has iov_len and
iov_ prefix does not help.  With "bytes" and "offset",
especially since they're now size_t, it is much more
explicit.  Also change the return type to be ssize_t
instead of int.

This also changes it to match other iov-related functons,
but not _quite_: there's still no argument indicating
where iovec ends, ie, no iov_cnt parameter as used
in iov_size() and friends.  If will be added in subsequent
patch/rewrite.

All callers of qemu_sendv() and qemu_recvv() and
related, like qemu_co_sendv() and qemu_co_recvv(),
were checked to verify that it is safe to use unsigned
datatype instead of int.

Note that the order of arguments is changed to: offset
and bytes (len and iov_offset) are swapped with each
other.  This is to make them consistent with very similar
functions from qemu_iovec family, where offset always
follows qiov, to mean the place in it to start from.

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

cutils.c

@@ -376,43 +376,28 @@ int qemu_parse_fd(const char *param)
     return fd;
 }
 
-/*
- * Send/recv data with iovec buffers
- *
- * This function send/recv data from/to the iovec buffer directly.
- * The first `offset' bytes in the iovec buffer are skipped and next
- * `len' bytes are used.
- *
- * For example,
- *
- *   do_sendv_recvv(sockfd, iov, len, offset, 1);
- *
- * is equal to
- *
- *   char *buf = malloc(size);
- *   iov_to_buf(iov, iovcnt, buf, offset, size);
- *   send(sockfd, buf, size, 0);
- *   free(buf);
- */
-static int do_sendv_recvv(int sockfd, struct iovec *iov, int len, int offset,
+static ssize_t do_sendv_recvv(int sockfd, struct iovec *iov,
+                          size_t offset, size_t bytes,
                           int do_sendv)
 {
-    int ret, diff, iovlen;
+    int iovlen;
+    ssize_t ret;
+    size_t diff;
     struct iovec *last_iov;
 
     /* last_iov is inclusive, so count from one.  */
     iovlen = 1;
     last_iov = iov;
-    len += offset;
+    bytes += offset;
 
-    while (last_iov->iov_len < len) {
-        len -= last_iov->iov_len;
+    while (last_iov->iov_len < bytes) {
+        bytes -= last_iov->iov_len;
 
         last_iov++;
         iovlen++;
     }
 
-    diff = last_iov->iov_len - len;
+    diff = last_iov->iov_len - bytes;
     last_iov->iov_len -= diff;
 
     while (iov->iov_len <= offset) {
@@ -474,13 +459,13 @@ static int do_sendv_recvv(int sockfd, struct iovec *iov, int len, int offset,
     return ret;
 }
 
-int qemu_recvv(int sockfd, struct iovec *iov, int len, int iov_offset)
+ssize_t iov_recv(int sockfd, struct iovec *iov, size_t offset, size_t bytes)
 {
-    return do_sendv_recvv(sockfd, iov, len, iov_offset, 0);
+    return do_sendv_recvv(sockfd, iov, offset, bytes, 0);
 }
 
-int qemu_sendv(int sockfd, struct iovec *iov, int len, int iov_offset)
+ssize_t iov_send(int sockfd, struct iovec *iov, size_t offset, size_t bytes)
 {
-    return do_sendv_recvv(sockfd, iov, len, iov_offset, 1);
+    return do_sendv_recvv(sockfd, iov, offset, bytes, 1);
 }
 

iov.h

@@ -54,6 +54,24 @@ size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
 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(sockfd, iov, offset, bytes);
+ *
+ * is logically equivalent to
+ *
+ *   char *buf = malloc(bytes);
+ *   iov_to_buf(iov, iovcnt, offset, buf, bytes);
+ *   r = send(sockfd, buf, bytes, 0);
+ *   free(buf);
+ */
+ssize_t iov_recv(int sockfd, struct iovec *iov, size_t offset, size_t bytes);
+ssize_t iov_send(int sockfd, struct iovec *iov, size_t offset, size_t bytes);
+
 /**
  * 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

qemu-common.h

@@ -205,9 +205,6 @@ int qemu_pipe(int pipefd[2]);
 #define qemu_recv(sockfd, buf, len, flags) recv(sockfd, buf, len, flags)
 #endif
 
-int qemu_recvv(int sockfd, struct iovec *iov, int len, int iov_offset);
-int qemu_sendv(int sockfd, struct iovec *iov, int len, int iov_offset);
-
 /* Error handling.  */
 
 void QEMU_NORETURN hw_error(const char *fmt, ...) GCC_FMT_ATTR(1, 2);

qemu-coroutine-io.c

@@ -25,6 +25,7 @@
 #include "qemu-common.h"
 #include "qemu_socket.h"
 #include "qemu-coroutine.h"
+#include "iov.h"
 
 int coroutine_fn qemu_co_recvv(int sockfd, struct iovec *iov,
                                int len, int iov_offset)
@@ -32,7 +33,7 @@ int coroutine_fn qemu_co_recvv(int sockfd, struct iovec *iov,
     int total = 0;
     int ret;
     while (len) {
-        ret = qemu_recvv(sockfd, iov, len, iov_offset + total);
+        ret = iov_recv(sockfd, iov, iov_offset + total, len);
         if (ret < 0) {
             if (errno == EAGAIN) {
                 qemu_coroutine_yield();
@@ -58,7 +59,7 @@ int coroutine_fn qemu_co_sendv(int sockfd, struct iovec *iov,
     int total = 0;
     int ret;
     while (len) {
-        ret = qemu_sendv(sockfd, iov, len, iov_offset + total);
+        ret = iov_send(sockfd, iov, iov_offset + total, len);
         if (ret < 0) {
             if (errno == EAGAIN) {
                 qemu_coroutine_yield();