Re: [Qemu-devel] [PATCH] New scriptarg=... -net parameter allows passing of an argument

[Anthony Liguori <anthony@codemonkey.ws>]

Ian Jackson wrote:
> Previously, network scripts would have to do all of their work based
> only on the script name and interface name.  If the script's behaviour
> is supposed to be different for different network interfaces this
> might involve constructing a special script for each interface with
> the associated need to delete it etc.
>   

env args should get passed down to the script although I can see an 
argument for being able to specify this in -net.  My only suggestion 
would be to use an env arg instead of "$2" as it will make it easier to 
extend in the future.

Regards,

Anthony Liguori

> With this patch it is possible to specify
>   -net=...,scriptarg=<extra-info>
> which gets passed as a $2 to the qemu-ifup script.
>
> Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
>
> ---
>  vl.c |   27 +++++++++++++++++++--------
>  1 files changed, 19 insertions(+), 8 deletions(-)
>
> diff --git a/vl.c b/vl.c
> index 229b536..28f6fe0 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -3963,6 +3963,7 @@ typedef struct TAPState {
>      VLANClientState *vc;
>      int fd;
>      char down_script[1024];
> +    char script_arg[1024];
>  } TAPState;
>  
>  static void tap_receive(void *opaque, const uint8_t *buf, int size)
> @@ -4198,10 +4199,11 @@ static int tap_open(char *ifname, int ifname_size)
>  }
>  #endif
>  
> -static int launch_script(const char *setup_script, const char *ifname, int fd)
> +static int launch_script(const char *setup_script, const char *ifname,
> +			 const char *script_arg, int fd)
>  {
>      int pid, status;
> -    char *args[3];
> +    char *args[4];
>      char **parg;
>  
>          /* try to launch network script */
> @@ -4219,6 +4221,8 @@ static int launch_script(const char *setup_script, const char *ifname, int fd)
>                  parg = args;
>                  *parg++ = (char *)setup_script;
>                  *parg++ = (char *)ifname;
> +                if (script_arg && script_arg[0])
> +                    *parg++ = (char *)script_arg;
>                  *parg++ = NULL;
>                  execv(setup_script, args);
>                  _exit(1);
> @@ -4235,7 +4239,8 @@ static int launch_script(const char *setup_script, const char *ifname, int fd)
>  }
>  
>  static int net_tap_init(VLANState *vlan, const char *ifname1,
> -                        const char *setup_script, const char *down_script)
> +                        const char *setup_script, const char *down_script,
> +                        const char *script_arg)
>  {
>      TAPState *s;
>      int fd;
> @@ -4252,7 +4257,7 @@ static int net_tap_init(VLANState *vlan, const char *ifname1,
>      if (!setup_script || !strcmp(setup_script, "no"))
>          setup_script = "";
>      if (setup_script[0] != '\0') {
> -	if (launch_script(setup_script, ifname, fd))
> +	if (launch_script(setup_script, ifname, script_arg, fd))
>  	    return -1;
>      }
>      s = net_tap_fd_init(vlan, fd);
> @@ -4262,6 +4267,8 @@ static int net_tap_init(VLANState *vlan, const char *ifname1,
>               "tap: ifname=%s setup_script=%s", ifname, setup_script);
>      if (down_script && strcmp(down_script, "no"))
>          snprintf(s->down_script, sizeof(s->down_script), "%s", down_script);
> +    if (script_arg && script_arg[0])
> +        snprintf(s->script_arg, sizeof(s->script_arg), "%s", script_arg);
>      return 0;
>  }
>  
> @@ -4854,7 +4861,7 @@ static int net_client_init(const char *str)
>  #else
>      if (!strcmp(device, "tap")) {
>          char ifname[64];
> -        char setup_script[1024], down_script[1024];
> +        char setup_script[1024], down_script[1024], script_arg[1024];
>          int fd;
>          vlan->nb_host_devs++;
>          if (get_param_value(buf, sizeof(buf), "fd", p) > 0) {
> @@ -4873,7 +4880,10 @@ static int net_client_init(const char *str)
>              if (get_param_value(down_script, sizeof(down_script), "downscript", p) == 0) {
>                  pstrcpy(down_script, sizeof(down_script), DEFAULT_NETWORK_DOWN_SCRIPT);
>              }
> -            ret = net_tap_init(vlan, ifname, setup_script, down_script);
> +            if (get_param_value(script_arg, sizeof(script_arg), "scriptarg", p) == 0) {
> +                pstrcpy(script_arg, sizeof(script_arg), "");
> +            }
> +            ret = net_tap_init(vlan, ifname, setup_script, down_script, script_arg);
>          }
>      } else
>  #endif
> @@ -7191,11 +7201,12 @@ static void help(int exitcode)
>             "-net tap[,vlan=n],ifname=name\n"
>             "                connect the host TAP network interface to VLAN 'n'\n"
>  #else
> -           "-net tap[,vlan=n][,fd=h][,ifname=name][,script=file][,downscript=dfile]\n"
> +           "-net tap[,vlan=n][,fd=h][,ifname=name][,script=file][,downscript=dfile][,scriptarg=extraargument]\n"
>             "                connect the host TAP network interface to VLAN 'n' and use the\n"
>             "                network scripts 'file' (default=%s)\n"
>             "                and 'dfile' (default=%s);\n"
>             "                use '[down]script=no' to disable script execution;\n"
> +           "                use 'scriptarg=...' to pass an additional (nonempty) argument;\n"
>             "                use 'fd=h' to connect to an already opened TAP interface\n"
>  #endif
>             "-net socket[,vlan=n][,fd=h][,listen=[host]:port][,connect=host:port]\n"
> @@ -8638,7 +8649,7 @@ int main(int argc, char **argv)
>  
>                  if (sscanf(vc->info_str, "tap: ifname=%63s ", ifname) == 1 &&
>                      s->down_script[0])
> -                    launch_script(s->down_script, ifname, s->fd);
> +                    launch_script(s->down_script, ifname, s->script_arg, s->fd);
>              }
>          }
>      }
>