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Re: [Xen-devel] [PATCH] libxl: prevent xl from running if xend is running.

Ian Jackson escribió:
Ian Campbell writes ("Re: [Xen-devel] [PATCH] libxl: prevent xl from running if xend 
      is running."):
On Tue, 2012-04-24 at 14:17 +0100, Ian Jackson wrote:
Can we somehow limit this to commands that actually change things ?
Having xl as a diagnostic tool even for xend-based systems is useful.
Perhaps a new flag in xl_cmdtable.h? Overriden by -f or -N (dry run).

Yes, something like that.

Do you mean to add a new "-f" option to each command that performs modifications, or modifying the cmd_spec struct to add something like "int modifies", and check that before trying to execute the command?

+        if (!access(locks[i], F_OK)&&  !force_execution) {
+            fprintf(stderr, "xend is running, which prevents xl from working "
+                            "correctly. If you still want to force the "
+                            "execution of xl please use the -f option\n");
+            exit(2);
+        }
If access fails with an unexpected error code (EACCES? EIO?) this will
blunder on.
It'll fail whether the error code is expected or not, won't it?

I think if access fails with EIO, it will return -1, and the if
condition will not be satisfied (!-1 = 0), so the fprintf and exit
will not be taken.


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