Re: [Qemu-devel] [PATCH V2 1/3] qemu-iotests: add unix socket help program

[Luiz Capitulino <lcapitulino@redhat.com>]

On Tue, 27 Aug 2013 10:52:09 +0800
Wenchao Xia <xiawenc@linux.vnet.ibm.com> wrote:

> This program can do a sendmsg call to transfer fd with unix
> socket, which is not supported in python2.
> 
> The built binary will not be deleted in clean, but it is a
> existing issue in ./tests, which should be solved in another
> patch.

Review comments in addition to Eric's.

> 
> Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
> ---
>  configure                              |    2 +-
>  tests/Makefile                         |    4 +-
>  tests/qemu-iotests/socket_scm_helper.c |  119 ++++++++++++++++++++++++++++++++
>  3 files changed, 123 insertions(+), 2 deletions(-)
>  create mode 100644 tests/qemu-iotests/socket_scm_helper.c
> 
> diff --git a/configure b/configure
> index 0a55c20..5080c38 100755
> --- a/configure
> +++ b/configure
> @@ -4544,7 +4544,7 @@ if [ "$dtc_internal" = "yes" ]; then
>  fi
>  
>  # build tree in object directory in case the source is not in the current directory
> -DIRS="tests tests/tcg tests/tcg/cris tests/tcg/lm32 tests/libqos tests/qapi-schema tests/tcg/xtensa"
> +DIRS="tests tests/tcg tests/tcg/cris tests/tcg/lm32 tests/libqos tests/qapi-schema tests/tcg/xtensa tests/qemu-iotests"
>  DIRS="$DIRS pc-bios/optionrom pc-bios/spapr-rtas pc-bios/s390-ccw"
>  DIRS="$DIRS roms/seabios roms/vgabios"
>  DIRS="$DIRS qapi-generated"
> diff --git a/tests/Makefile b/tests/Makefile
> index baba9e9..d2f3fcb 100644
> --- a/tests/Makefile
> +++ b/tests/Makefile
> @@ -172,6 +172,8 @@ tests/boot-order-test$(EXESUF): tests/boot-order-test.o $(libqos-obj-y)
>  tests/tmp105-test$(EXESUF): tests/tmp105-test.o $(libqos-omap-obj-y)
>  tests/i440fx-test$(EXESUF): tests/i440fx-test.o $(libqos-pc-obj-y)
>  tests/fw_cfg-test$(EXESUF): tests/fw_cfg-test.o $(libqos-pc-obj-y)
> +tests/qemu-iotests/socket_scm_helper$(EXESUF): tests/qemu-iotests/socket_scm_helper.o
> +	$(call LINK, $^)
>  
>  # QTest rules
>  
> @@ -250,7 +252,7 @@ check-report.html: check-report.xml
>  # Other tests
>  
>  .PHONY: check-tests/qemu-iotests-quick.sh
> -check-tests/qemu-iotests-quick.sh: tests/qemu-iotests-quick.sh qemu-img$(EXESUF) qemu-io$(EXESUF)
> +check-tests/qemu-iotests-quick.sh: tests/qemu-iotests-quick.sh qemu-img$(EXESUF) qemu-io$(EXESUF) tests/qemu-iotests/socket_scm_helper$(EXESUF)
>  	$<
>  
>  .PHONY: check-tests/test-qapi.py
> diff --git a/tests/qemu-iotests/socket_scm_helper.c b/tests/qemu-iotests/socket_scm_helper.c
> new file mode 100644
> index 0000000..1955a3e
> --- /dev/null
> +++ b/tests/qemu-iotests/socket_scm_helper.c
> @@ -0,0 +1,119 @@
> +/*
> + * SCM_RIGHT with unix socket help program for test
> + *
> + * Copyright IBM, Inc. 2013
> + *
> + * Authors:
> + *  Wenchao Xia    <xiawenc@linux.vnet.ibm.com>
> + *
> + * This work is licensed under the terms of the GNU LGPL, version 2 or later.
> + * See the COPYING.LIB file in the top-level directory.
> + */
> +
> +#include <stdio.h>
> +#include <errno.h>
> +#include <sys/socket.h>
> +#include <sys/un.h>
> +#include <stdlib.h>
> +
> +/* #define SOCKET_SCM_DEBUG */
> +
> +static int send_fd(int fd, int fd_to_send, const char *data, size_t len)
> +{
> +    struct msghdr msg;
> +    struct iovec iov[1];
> +    int ret;
> +    char control[CMSG_SPACE(sizeof(int))];
> +    struct cmsghdr *cmsg;
> +
> +    if (fd < 0) {
> +        fprintf(stderr, "Socket fd is invalid.\n");
> +        return -1;
> +    }
> +    if (fd_to_send < 0) {
> +        fprintf(stderr, "Fd to send is invalid.\n");
> +        return -1;
> +    }
> +    if (data == NULL || len <= 0) {
> +        fprintf(stderr, "Data buffer must be valid.\n");
> +        return -1;
> +    }

I haven't looked at the test itself yet, but my idea for the helper was
to have something like "pass-fd < file > < qmp-socket >". So, what the
helper does is to open 'file' and pass its fd to 'qmp-socket'. Seems
simpler to me.

> +
> +    memset(&msg, 0, sizeof(msg));
> +    memset(control, 0, sizeof(control));
> +
> +    iov[0].iov_base = (void *)data;
> +    iov[0].iov_len = len;
> +
> +    msg.msg_iov = iov;
> +    msg.msg_iovlen = 1;
> +
> +    msg.msg_control = control;
> +    msg.msg_controllen = sizeof(control);
> +
> +    cmsg = CMSG_FIRSTHDR(&msg);
> +
> +    cmsg->cmsg_len = CMSG_LEN(sizeof(int));
> +    cmsg->cmsg_level = SOL_SOCKET;
> +    cmsg->cmsg_type = SCM_RIGHTS;
> +    memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));
> +
> +    do {
> +        ret = sendmsg(fd, &msg, 0);
> +    } while (ret < 0 && errno == EINTR);
> +
> +    if (ret < 0) {
> +        fprintf(stderr, "Failed to send msg, reason: %s.\n", strerror(errno));
> +    }
> +
> +    return ret;
> +}
> +
> +/*
> + * To make things simple, the caller need to specify:
> + * 1. socket fd.
> + * 2. fd to send.
> + * 3. msg to send.
> + */
> +int main(int argc, char **argv, char **envp)
> +{
> +    int sock, fd, ret, buflen;
> +    const char *buf;
> +#ifdef SOCKET_SCM_DEBUG
> +    int i;
> +    for (i = 0; i < argc; i++) {
> +        fprintf(stderr, "Parameter %d: %s.\n", i, argv[i]);
> +    }
> +#endif
> +
> +    if (argc < 4) {
> +        fprintf(stderr,
> +                "Invalid parameter, use it as:\n"
> +                "%s SOCKET_FD FD_TO_SEND MSG.\n",
> +                argv[0]);
> +        return 1;
> +    }

Some like "usage: %s < socket-fd > < fd-to-send > < msg >\n" is more
readable, IMO.

> +
> +    errno = 0;
> +    sock = strtol(argv[1], NULL, 10);
> +    if (errno) {
> +        fprintf(stderr, "Failed in strtol for socket fd, reason: %s.\n",
> +                strerror(errno));
> +        return 1;
> +    }

Apart from what Eric suggested, you could move this to a function.

> +    fd = strtol(argv[2], NULL, 10);
> +    if (errno) {
> +        fprintf(stderr, "Failed in strtol for fd to send, reason: %s.\n",
> +                strerror(errno));
> +        return 1;
> +    }
> +
> +    buf = argv[3];
> +    buflen = strlen(buf);
> +
> +    ret = send_fd(sock, fd, buf, buflen);
> +    if (ret < 0) {
> +        return 1;
> +    }
> +    return 0;
> +}