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

[Thomas Huth <thuth@redhat.com>]

On 19/10/2022 09.09, Bin Meng wrote:
> 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.

I think it needs an #include statement from an earlier patch?

  Thomas