[Qemu-devel] Re: [RFC][PATCH v5 07/21] virtagent: add va.getfile RPC

[Michael Roth]

On 12/06/2010 04:06 PM, Adam Litke wrote:
> On Fri, 2010-12-03 at 12:03 -0600, Michael Roth wrote:
> > Add RPC to retrieve a guest file. This interface is intended
> > for smaller reads like peeking at logs and /proc and such.
> >
> > Signed-off-by: Michael Roth<address@hidden>
> > ---
> >   virtagent-server.c |   59 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >   1 files changed, 59 insertions(+), 0 deletions(-)
> >
> > diff --git a/virtagent-server.c b/virtagent-server.c
> > index 36fbae2..a430b58 100644
> > --- a/virtagent-server.c
> > +++ b/virtagent-server.c
> > @@ -26,12 +26,71 @@ static bool va_enable_syslog = false; /* enable syslog'ing 
> > of RPCs */
> >       syslog(LOG_INFO, "virtagent, %s", msg_buf); \
> >   } while(0)
> >
> > +/* RPC functions common to guest/host daemons */
> > +
> > +/* va_getfile(): return file contents
> > + * rpc return values:
> > + *   - base64-encoded file contents
> > + */
> > +static xmlrpc_value *va_getfile(xmlrpc_env *env,
> > +                                xmlrpc_value *param,
> > +                                void *user_data)
> > +{
> > +    const char *path;
> > +    char *file_contents = NULL;
> > +    char buf[VA_FILEBUF_LEN];
> > +    int fd, ret, count = 0;
> > +    xmlrpc_value *result = NULL;
> > +
> > +    /* parse argument array */
> > +    xmlrpc_decompose_value(env, param, "(s)",&path);
> > +    if (env->fault_occurred) {
> > +        return NULL;
> > +    }
> > +
> > +    SLOG("va_getfile(), path:%s", path);
>
> I would log all calls (even those that would fail
> xmlrpc_decompose_value(). You might catch someone trying to do something
> tricky.

Agreed, I'll fix this up for the next round

> > +
> > +    fd = open(path, O_RDONLY);
> > +    if (fd == -1) {
> > +        LOG("open failed: %s", strerror(errno));
> > +        xmlrpc_faultf(env, "open failed: %s", strerror(errno));
> > +        return NULL;
> > +    }
> > +
> > +    while ((ret = read(fd, buf, VA_FILEBUF_LEN))>  0) {
> > +        file_contents = qemu_realloc(file_contents, count + VA_FILEBUF_LEN);
> > +        memcpy(file_contents + count, buf, ret);
> > +        count += ret;
> > +        if (count>  VA_GETFILE_MAX) {
> > +            xmlrpc_faultf(env, "max file size (%d bytes) exceeded",
> > +                          VA_GETFILE_MAX);
> > +            goto EXIT_CLOSE_BAD;
> > +        }
> > +    }
> > +    if (ret == -1) {
> > +        LOG("read failed: %s", strerror(errno));
> > +        xmlrpc_faultf(env, "read failed: %s", strerror(errno));
> > +        goto EXIT_CLOSE_BAD;
> > +    }
> > +
> > +    result = xmlrpc_build_value(env, "6", file_contents, count);
> > +
> > +EXIT_CLOSE_BAD:
> > +    if (file_contents) {
> > +        qemu_free(file_contents);
> > +    }
> > +    close(fd);
> > +    return result;
> > +}
> > +
> >   typedef struct RPCFunction {
> >       xmlrpc_value *(*func)(xmlrpc_env *env, xmlrpc_value *param, void *unused);
> >       const char *func_name;
> >   } RPCFunction;
> >
> >   static RPCFunction guest_functions[] = {
> > +    { .func = va_getfile,
> > +      .func_name = "va.getfile" },
> >       { NULL, NULL }
> >   };
> >   static RPCFunction host_functions[] = {