Re: [PATCH v2 16/39] tests/qtest: Use send/recv for socket communication

["Marc-André Lureau" <marcandre.lureau@gmail.com>]

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On Tue, Sep 20, 2022 at 2:23 PM Bin Meng <bmeng.cn@gmail.com> wrote:

> From: Xuzhou Cheng <xuzhou.cheng@windriver.com>
>
> Socket communication in the libqtest and libqmp codes uses read()
> and write() which work on any file descriptor on *nix, and sockets
> in *nix are an example of a file descriptor.
>
> However sockets on Windows do not use *nix-style file descriptors,
> so read() and write() cannot be used on sockets on Windows.
> Switch over to use send() and recv() instead which work on both
> Windows and *nix.
>
> Signed-off-by: Xuzhou Cheng <xuzhou.cheng@windriver.com>
> Signed-off-by: Bin Meng <bin.meng@windriver.com>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>


> ---
>
> Changes in v2:
> - Introduce qemu_send_full() and use it
>
>  include/qemu/sockets.h |  2 ++
>  tests/qtest/libqmp.c   |  5 +++--
>  tests/qtest/libqtest.c |  4 ++--
>  util/osdep.c           | 33 +++++++++++++++++++++++++++++++++
>  4 files changed, 40 insertions(+), 4 deletions(-)
>
> diff --git a/include/qemu/sockets.h b/include/qemu/sockets.h
> index 038faa157f..8ff7832eba 100644
> --- a/include/qemu/sockets.h
> +++ b/include/qemu/sockets.h
> @@ -15,6 +15,8 @@ int inet_aton(const char *cp, struct in_addr *ia);
>  bool fd_is_socket(int fd);
>  int qemu_socket(int domain, int type, int protocol);
>  int qemu_accept(int s, struct sockaddr *addr, socklen_t *addrlen);
> +ssize_t qemu_send_full(int s, const void *buf, size_t count)
> +    G_GNUC_WARN_UNUSED_RESULT;
>  int socket_set_cork(int fd, int v);
>  int socket_set_nodelay(int fd);
>  void qemu_socket_set_block(int fd);
> diff --git a/tests/qtest/libqmp.c b/tests/qtest/libqmp.c
> index ade26c15f0..2b08382e5d 100644
> --- a/tests/qtest/libqmp.c
> +++ b/tests/qtest/libqmp.c
> @@ -23,6 +23,7 @@
>  #endif
>
>  #include "qemu/cutils.h"
> +#include "qemu/sockets.h"
>  #include "qapi/error.h"
>  #include "qapi/qmp/json-parser.h"
>  #include "qapi/qmp/qjson.h"
> @@ -36,7 +37,7 @@ typedef struct {
>
>  static void socket_send(int fd, const char *buf, size_t size)
>  {
> -    size_t res = qemu_write_full(fd, buf, size);
> +    ssize_t res = qemu_send_full(fd, buf, size);
>
>      assert(res == size);
>  }
> @@ -69,7 +70,7 @@ QDict *qmp_fd_receive(int fd)
>          ssize_t len;
>          char c;
>
> -        len = read(fd, &c, 1);
> +        len = recv(fd, &c, 1, 0);
>          if (len == -1 && errno == EINTR) {
>              continue;
>          }
> diff --git a/tests/qtest/libqtest.c b/tests/qtest/libqtest.c
> index a0f28ddf8e..a25a8b47d0 100644
> --- a/tests/qtest/libqtest.c
> +++ b/tests/qtest/libqtest.c
> @@ -436,7 +436,7 @@ void qtest_quit(QTestState *s)
>
>  static void socket_send(int fd, const char *buf, size_t size)
>  {
> -    size_t res = qemu_write_full(fd, buf, size);
> +    ssize_t res = qemu_send_full(fd, buf, size);
>
>      assert(res == size);
>  }
> @@ -468,7 +468,7 @@ static GString
> *qtest_client_socket_recv_line(QTestState *s)
>          ssize_t len;
>          char buffer[1024];
>
> -        len = read(s->fd, buffer, sizeof(buffer));
> +        len = recv(s->fd, buffer, sizeof(buffer), 0);
>          if (len == -1 && errno == EINTR) {
>              continue;
>          }
> diff --git a/util/osdep.c b/util/osdep.c
> index 60fcbbaebe..0342e754e1 100644
> --- a/util/osdep.c
> +++ b/util/osdep.c
> @@ -502,6 +502,39 @@ int qemu_accept(int s, struct sockaddr *addr,
> socklen_t *addrlen)
>      return ret;
>  }
>
> +/*
> + * A variant of send(2) which handles partial send.
> + *
> + * Return the number of bytes transferred over the socket.
> + * Set errno if fewer than `count' bytes are sent.
> + *
> + * This function don't work with non-blocking socket's.
> + * Any of the possibilities with non-blocking socket's is bad:
> + *   - return a short write (then name is wrong)
> + *   - busy wait adding (errno == EAGAIN) to the loop
> + */
> +ssize_t qemu_send_full(int s, const void *buf, size_t count)
> +{
> +    ssize_t ret = 0;
> +    ssize_t total = 0;
> +
> +    while (count) {
> +        ret = send(s, buf, count, 0);
> +        if (ret < 0) {
> +            if (errno == EINTR) {
> +                continue;
> +            }
> +            break;
> +        }
> +
> +        count -= ret;
> +        buf += ret;
> +        total += ret;
> +    }
> +
> +    return total;
> +}
> +
>  void qemu_set_hw_version(const char *version)
>  {
>      hw_version = version;
> --
> 2.34.1
>
>
>

-- 
Marc-André Lureau

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