Re: [Qemu-devel] [PATCH V2] Support logging xen-guest console

[Chun Yan Liu]

On Thursday, June 23, 2011 02:22:37 AM Anthony Liguori wrote:
> On 06/22/2011 02:26 AM, Chunyan Liu wrote:
> > Add code to support logging xen-domU console, as what xenconsoled does.
> > Log info will be saved in /var/log/xen/console/guest-domUname.log.
> 
> It needs to be specified by command line.  It's not appropriate to
> assume qemu is running as root with access to a non-user directory.

Sorry, I'm late to reply. I just come back from vocation. Thanks for your 
remindness. But I think adding a command line option to qemu seems not proper, 
after all, it's a function to xen only. Like XENCONSOLED_TRACE, use 
XENCONSOLED_LOGDIR environment variable instead. Will post V3.

Thanks,
Chunyan

> Regards,
> 
> Anthony Liguori
> 
> > Signed-off-by: Chunyan Liu<address@hidden>
> > ---
> > 
> >   hw/xen_console.c |   71
> >   ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files
> >   changed, 71 insertions(+), 0 deletions(-)
> > 
> > diff --git a/hw/xen_console.c b/hw/xen_console.c
> > index c6c8163..f898e4f 100644
> > --- a/hw/xen_console.c
> > +++ b/hw/xen_console.c
> > @@ -36,6 +36,8 @@
> > 
> >   #include "qemu-char.h"
> >   #include "xen_backend.h"
> > 
> > +static int log_guest = 0;
> > +
> > 
> >   struct buffer {
> >   
> >       uint8_t *data;
> >       size_t consumed;
> > 
> > @@ -52,8 +54,24 @@ struct XenConsole {
> > 
> >       void              *sring;
> >       CharDriverState   *chr;
> >       int               backlog;
> > 
> > +    int               log_fd;
> > 
> >   };
> > 
> > +static int write_all(int fd, const char* buf, size_t len)
> > +{
> > +    while (len) {
> > +        ssize_t ret = write(fd, buf, len);
> > +        if (ret == -1&&  errno == EINTR)
> > +            continue;
> > +        if (ret<  0)
> > +            return -1;
> > +        len -= ret;
> > +        buf += ret;
> > +    }
> > +
> > +    return 0;
> > +}
> > +
> > 
> >   static void buffer_append(struct XenConsole *con)
> >   {
> >   
> >       struct buffer *buffer =&con->buffer;
> > 
> > @@ -81,6 +99,15 @@ static void buffer_append(struct XenConsole *con)
> > 
> >       intf->out_cons = cons;
> >       xen_be_send_notify(&con->xendev);
> > 
> > +    if (con->log_fd != -1) {
> > +        int logret;
> > +        logret = write_all(con->log_fd, buffer->data + buffer->size -
> > size, size); +        if (logret<  0) {
> > +            xen_be_printf(&con->xendev, 1, "Write to log failed on
> > domain %d: %d (%s)\n", +                      con->xendev.dom, errno,
> > strerror(errno)); +        }
> > +     }
> > +
> > 
> >       if (buffer->max_capacity&&
> >     
> >     buffer->size>  buffer->max_capacity) {
> >     /* Discard the middle of the data. */
> > 
> > @@ -174,12 +201,43 @@ static void xencons_send(struct XenConsole *con)
> > 
> >       }
> >   
> >   }
> > 
> > +static int create_domain_log(struct XenConsole *con)
> > +{
> > +    char *logfile;
> > +    char *path, *domname;
> > +    int fd;
> > +    const char *logdir = "/var/log/xen/console";
> > +
> > +    path = xs_get_domain_path(xenstore, con->xendev.dom);
> > +    domname = xenstore_read_str(path, "name");
> > +    free(path);
> > +    if (!domname)
> > +        return -1;
> > +
> > +    if (mkdir(logdir, 0755)&&  errno != EEXIST)
> > +    {
> > +        xen_be_printf(&con->xendev, 1,  "Directory %s does not exist and
> > fail to create it!", logdir); +        return -1;
> > +    }
> > +
> > +    asprintf(&logfile, "%s/guest-%s.log", logdir, domname);
> > +    qemu_free(domname);
> > +
> > +    fd = open(logfile, O_WRONLY|O_CREAT|O_APPEND, 0644);
> > +    free(logfile);
> > +    if (fd == -1)
> > +        xen_be_printf(&con->xendev, 1,  "Failed to open log %s: %d
> > (%s)", logfile, errno, strerror(errno)); +
> > +    return fd;
> > +}
> > +
> > 
> >   /* --------------------------------------------------------------------
> >   */
> >   
> >   static int con_init(struct XenDevice *xendev)
> >   {
> >   
> >       struct XenConsole *con = container_of(xendev, struct XenConsole,
> >       xendev); char *type, *dom;
> > 
> > +    char *logenv = NULL;
> > 
> >       /* setup */
> >       dom = xs_get_domain_path(xenstore, con->xendev.dom);
> > 
> > @@ -198,6 +256,10 @@ static int con_init(struct XenDevice *xendev)
> > 
> >       else
> >       
> >           con->chr = serial_hds[con->xendev.dev];
> > 
> > +    logenv = getenv("XENCONSOLED_TRACE");
> > +    if (logenv != NULL&&  strlen(logenv) == strlen("guest")&& 
> > !strcmp(logenv, "guest")) { +        log_guest = 1;
> > +    }
> > 
> >       return 0;
> >   
> >   }
> > 
> > @@ -230,6 +292,9 @@ static int con_connect(struct XenDevice *xendev)
> > 
> >               con->xendev.remote_port,
> >               con->xendev.local_port,
> >               con->buffer.max_capacity);
> > 
> > +    con->log_fd = -1;
> > +    if (log_guest)
> > +         con->log_fd = create_domain_log(con);
> > 
> >       return 0;
> >   
> >   }
> > 
> > @@ -245,6 +310,12 @@ static void con_disconnect(struct XenDevice *xendev)
> > 
> >     munmap(con->sring, XC_PAGE_SIZE);
> >     con->sring = NULL;
> >     
> >       }
> > 
> > +
> > +    if (con->log_fd != -1) {
> > +        close(con->log_fd);
> > +        con->log_fd = -1;
> > +    }
> > +
> > 
> >   }
> >   
> >   static void con_event(struct XenDevice *xendev)