Re: [PATCH]: xl: catch invalid numeric domain ID

[Andre Przywara <andre.przywara@amd.com>]

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On 01/21/2011 08:03 PM, Ian Jackson wrote:
> Andre Przywara writes ("[PATCH]: xl: catch invalid numeric domain ID"):
>> if you run any domain specific xl command with an invalid (aka
>> non-existing) numeric domain ID, the command does not abort, but
>> proceeds with some bogus number:
>
> Thanks, but I'm not 100% convinced that it is impossible to ever get
> into a situation where a domain exists but has no name.  In that case,
> this patch of yours would leave an undestroyable domain.
>
> I think the right answer is to use libxl_domain_info to check whether
> the domain exists.  It returns ERROR_INVAL, without logging anything,
> if the domain does not exist.  On other failures xl destroy should
> probably carry on and attempt to destroy the domain.
OK, I looked around the bit, libxl_domain_info really seems to be the 
easiest solution. So please consider the attached patch. I am not 100% 
happy with it, actually I think find_domain should return an error 
value. In this case we could abort the commands gracefully (like xl list 
does) and avoid the rather impolite exit(2).
On the other hand I am not sure if fixing the 30 or so callers of 
find_domain() is appropriate in this state of development.
Please tell me if you prefer this more elaborated version and I will 
send a patch.

Regards,
Andre.

-- 
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany


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diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 359970b..deae3f7 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -163,12 +163,18 @@ static int cpupool_qualifier_to_cpupoolid(const char *p, uint32_t *poolid_r,
 static void find_domain(const char *p)
 {
     int rc, was_name;
+    libxl_dominfo info_buf;
 
     rc = domain_qualifier_to_domid(p, &domid, &was_name);
     if (rc) {
         fprintf(stderr, "%s is an invalid domain identifier (rc=%d)\n", p, rc);
         exit(2);
     }
+    rc = libxl_domain_info(&ctx, &info_buf, domid);
+    if (rc == ERROR_INVAL) {
+        fprintf(stderr, "Error: Domain \'%d\' does not exist.\n", domid);
+        exit(2);
+    }
     common_domname = was_name ? p : libxl_domid_to_name(&ctx, domid);
 }
 
@@ -3149,11 +3155,6 @@ int main_list(int argc, char **argv)
     } else if (optind == argc-1) {
         find_domain(argv[optind]);
         rc = libxl_domain_info(&ctx, &info_buf, domid);
-        if (rc == ERROR_INVAL) {
-            fprintf(stderr, "Error: Domain \'%s\' does not exist.\n",
-                argv[optind]);
-            return -rc;
-        }
         if (rc) {
             fprintf(stderr, "libxl_domain_info failed (code %d).\n", rc);
             return -rc;

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