Re: [Qemu-devel] [RFC][PATCH 07/10] virtagent: add getdmesg RPC

[Anthony Liguori <anthony@codemonkey.ws>]

On 10/22/2010 01:46 PM, Michael Roth wrote:
> Add RPC to view guest dmesg output.
>
> Signed-off-by: Michael Roth<mdroth@linux.vnet.ibm.com>
> ---
>   virtagent-daemon.c |   45 +++++++++++++++++++++++++++++++++++++++++++++
>   virtagent-daemon.h |    1 +
>   2 files changed, 46 insertions(+), 0 deletions(-)
>
> diff --git a/virtagent-daemon.c b/virtagent-daemon.c
> index fad0f64..6aaa987 100644
> --- a/virtagent-daemon.c
> +++ b/virtagent-daemon.c
> @@ -72,6 +72,48 @@ EXIT_CLOSE_BAD:
>       return result;
>   }
>
> +/* getdmesg(): return dmesg output
> + * rpc return values:
> + *   - dmesg output as a string
> + */
> +static xmlrpc_value *getdmesg(xmlrpc_env *env,
> +                              xmlrpc_value *param,
> +                              void *user_data)
> +{
> +    char *dmesg_buf = NULL, cmd[256];
> +    char c;
> +    int pos = 0;
> +    xmlrpc_value *result = NULL;
> +    FILE *pipe;
> +
> +    dmesg_buf = qemu_mallocz(VA_DMESG_LEN + 2048);
> +    sprintf(cmd, "dmesg -s %d", VA_DMESG_LEN);
> +
> +    //pipe = popen(cmd, "r");
> +    pipe = popen("dmesg -s 16000", "r");
> +    if (pipe == NULL) {
> +        LOG("popen failed: %s", strerror(errno));
> +        xmlrpc_faultf(env, "popen failed: %s", strerror(errno));
> +        goto EXIT_NOCLOSE;
> +    }
> +
> +    while ((c = fgetc(pipe)) != EOF&&  pos<  VA_DMESG_LEN) {
> +        dmesg_buf[pos] = c;
> +        pos++;
> +    }
>    

fgetc seems a bit odd here.  Why not fread?

Regards,

Anthony Liguori

> +    dmesg_buf[pos++] = '\0';
> +    TRACE("dmesg:\n%s", dmesg_buf);
> +
> +    result = xmlrpc_build_value(env, "s", dmesg_buf);
> +    pclose(pipe);
> +EXIT_NOCLOSE:
> +    if (dmesg_buf) {
> +        qemu_free(dmesg_buf);
> +    }
> +
> +    return result;
> +}
> +
>   static int va_accept(int listen_fd) {
>       struct sockaddr_in saddr;
>       struct sockaddr *addr;
> @@ -101,6 +143,8 @@ typedef struct RPCFunction {
>   static RPCFunction guest_functions[] = {
>       { .func = getfile,
>         .func_name = "getfile" },
> +    { .func = getdmesg,
> +      .func_name = "getdmesg" },
>       { NULL, NULL }
>   };
>   static RPCFunction host_functions[] = {
> @@ -165,6 +209,7 @@ int va_server_loop(int listen_fd, bool is_host)
>           XMLRPC_MEMBLOCK_FREE(char, rpc_response);
>   out:
>           closesocket(fd);
> +        xmlrpc_env_clean(&env);
>       }
>
>       return 0;
> diff --git a/virtagent-daemon.h b/virtagent-daemon.h
> index bb197d0..adcbc9a 100644
> --- a/virtagent-daemon.h
> +++ b/virtagent-daemon.h
> @@ -16,5 +16,6 @@
>   #define HOST_AGENT_PATH "/tmp/virtagent-host.sock"
>   #define VA_GETFILE_MAX 1<<  30
>   #define VA_FILEBUF_LEN 16384
> +#define VA_DMESG_LEN 16384
>
>   int va_server_loop(int listen_fd, bool is_host);
>