sheepdog: move coroutine send/recv function to generic code

Outside coroutines, avoid busy waiting on EAGAIN by temporarily
making the socket blocking.

The API of qemu_recvv/qemu_sendv is slightly different from
do_readv/do_writev because they do not handle coroutines.  It
returns the number of bytes written before encountering an
EAGAIN.  The specificity of yielding on EAGAIN is entirely in
qemu-coroutine.c.

Reviewed-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 31 insertions, 1 deletions

diff --git a/qemu-common.h b/qemu-common.h
index 5c3f3af6aa..6ab7dfb1b9 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -175,7 +175,7 @@ ssize_t qemu_write_full(int fd, const void *buf, size_t count)
     QEMU_WARN_UNUSED_RESULT;
 ssize_t qemu_send_full(int fd, const void *buf, size_t count, int flags)
     QEMU_WARN_UNUSED_RESULT;
-ssize_t qemu_recv_full(int fd, const void *buf, size_t count, int flags)
+ssize_t qemu_recv_full(int fd, void *buf, size_t count, int flags)
     QEMU_WARN_UNUSED_RESULT;
 void qemu_set_cloexec(int fd);
 
@@ -190,6 +190,9 @@ 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);
@@ -276,6 +279,33 @@ struct qemu_work_item {
 void qemu_init_vcpu(void *env);
 #endif
 
+/**
+ * Sends an iovec (or optionally a part of it) down a socket, yielding
+ * when the socket is full.
+ */
+int qemu_co_sendv(int sockfd, struct iovec *iov,
+                  int len, int iov_offset);
+
+/**
+ * Receives data into an iovec (or optionally into a part of it) from
+ * a socket, yielding when there is no data in the socket.
+ */
+int qemu_co_recvv(int sockfd, struct iovec *iov,
+                  int len, int iov_offset);
+
+
+/**
+ * Sends a buffer down a socket, yielding when the socket is full.
+ */
+int qemu_co_send(int sockfd, void *buf, int len);
+
+/**
+ * Receives data into a buffer from a socket, yielding when there
+ * is no data in the socket.
+ */
+int qemu_co_recv(int sockfd, void *buf, int len);
+
+
 typedef struct QEMUIOVector {
     struct iovec *iov;
     int niov;