Re: [PATCH v5 09/18] tests/qtest: Use send/recv for socket communication

[Bin Meng <bmeng.cn@gmail.com>]

On Wed, Oct 19, 2022 at 12:47 AM Alex Bennée <alex.bennee@linaro.org> wrote:
>
>
> Bin Meng <bmeng.cn@gmail.com> writes:
>
> > 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>
> > ---
> >
> > (no changes since v2)
> >
> > 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 036745e586..adf2b21bd9 100644
> > --- a/include/qemu/sockets.h
> > +++ b/include/qemu/sockets.h
> > @@ -33,6 +33,8 @@ int qemu_socketpair(int domain, int type, int protocol, int sv[2]);
> >  #endif
> >
> >  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 4f4b2d6477..8228262938 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;
>
> Hmm something goes wrong here:
>
> FAILED: tests/qtest/libqos/libqos.fa.p/.._libqtest.c.o
> cc -m64 -mcx16 -Itests/qtest/libqos/libqos.fa.p -Itests/qtest/libqos -I../../tests/qtest/libqos -I. -Iqapi -Itrace -Iui -Iui/shader -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -fdiagnostics-color=auto -Wall -Winvalid-pch -Werror -std=gnu11 -O2 -g -isystem /home/alex/lsrc/qemu.git/linux-headers -isystem linux-headers -iquote . -iquote /home/alex/lsrc/qemu.git -iquote /home/alex/lsrc/qemu.git/include -iquote /home/alex/lsrc/qemu.git/tcg/i386 -pthread -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wundef -Wwrite-strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv -Wold-style-declaration -Wold-style-definition -Wtype-limits -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body -Wnested-externs -Wendif-labels -Wexpansion-to-defined -Wimplicit-fallthrough=2 -Wno-missing-include-dirs -Wno-shift-negative-value -Wno-psabi -fstack-protector-strong -fPIE -MD -MQ tests/qtest/libqos/libqos.fa.p/.._libqtest.c.o -MF tests/qtest/libqos/libqos.fa.p/.._libqtest.c.o.d -o tests/qtest/libqos/libqos.fa.p/.._libqtest.c.o -c ../../tests/qtest/libqtest.c
> ../../tests/qtest/libqtest.c: In function ‘socket_send’:
> ../../tests/qtest/libqtest.c:431:19: error: implicit declaration of function ‘qemu_send_full’; did you mean ‘qemu_write_full’? [-Werror=implicit-function-declaration]
>   431 |     ssize_t res = qemu_send_full(fd, buf, size);
>       |                   ^~~~~~~~~~~~~~
>       |                   qemu_write_full
> ../../tests/qtest/libqtest.c:431:19: error: nested extern declaration of ‘qemu_send_full’ [-Werror=nested-externs]
> cc1: all warnings being treated as errors
>
>
> dropping this patch.
>

This is weird. It does not reproduce on my side, neither did the QEMU CI.

Regards,
Bin