Re: [Xen-devel] Using "xl create" without domain config file

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

W. Michael Petullo writes ("Re: [Xen-devel] Using "xl create" without domain 
config file"):
> [...]
> > Another alternative would be to special-case the string "/dev/null"
> > (in xl, not libxl) and not read a config file at all in that case.
> 
> This patch treats /dev/null as a special case.

Thanks, this is going in the right direction I think.  Just two
niggles:

> diff -r 435493696053 tools/libxl/xl_cmdimpl.c
> --- a/tools/libxl/xl_cmdimpl.c  Fri May 25 08:18:47 2012 +0100
> +++ b/tools/libxl/xl_cmdimpl.c  Thu Jun 07 22:40:58 2012 -0500
> @@ -1454,10 +1454,13 @@ static int create_domain(struct domain_c
> 
>      if (config_file) {
>          free(config_data);  config_data = 0;
...
> +        // /dev/null represents special case (read config. from command line)

libxl coding style uses /*...*/ comments.

> +        if (strcmp(config_file, "/dev/null")) {
> +            ret = libxl_read_file_contents(&ctx, config_file,
> +                                           &config_data, &config_len);

I think this fails to set config_len to 0 in the /dev/null case, which
it should do.  Although config_len is initialised to 0 it may have
been set to a non-0 value from the length of the old config file if
we're doing a restore, and in this case it needs to be rezeroed.

> +            if (ret) { fprintf(stderr, "Failed to read config file: %s: 
> %s\n",
> +                               config_file, strerror(errno)); return 
> ERROR_FAIL; }
> +        }
>          if (!restore_file && extra_config && strlen(extra_config)) {
>              if (config_len > INT_MAX - (strlen(extra_config) + 2 + 1)) {
>                  fprintf(stderr, "Failed to attach extra configration\n");

thanks,
Ian.

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