Re: [Xen-devel] [PATCH] ocaml/xenctrl: Make failwith_xc() thread safe

[Dave Scott <Dave.Scott@xxxxxxxxxx>]

Looks ok to me.

Signed-off-by: David Scott <dave.scott@xxxxxxxxxx>

> On 28 Jan 2015, at 17:55, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> 
> The static error_str[] buffer is not thread-safe, and 1024 bytes is
> unreasonably large.  Reduce to 256 bytes (which is still much larger than any
> current use), and move it to being a stack variable.
> 
> Also, propagate the Noreturn attribute from caml_raise_with_string().
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> CC: Dave Scott <Dave.Scott@xxxxxxxxxxxxx>
> CC: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
> CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> ---
> tools/ocaml/libs/xc/xenctrl_stubs.c |   15 ++++++++-------
> 1 file changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c 
> b/tools/ocaml/libs/xc/xenctrl_stubs.c
> index 92d064f..6a95528 100644
> --- a/tools/ocaml/libs/xc/xenctrl_stubs.c
> +++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
> @@ -51,21 +51,22 @@
>       i1 = (uint32_t) Int64_val(Field(input, 0)); \
>       i2 = ((Field(input, 1) == Val_none) ? 0xffffffff : (uint32_t) 
> Int64_val(Field(Field(input, 1), 0)));
> 
> -#define ERROR_STRLEN 1024
> -void failwith_xc(xc_interface *xch)
> +static void Noreturn failwith_xc(xc_interface *xch)
> {
> -     static char error_str[ERROR_STRLEN];
> +     char error_str[256];
>       if (xch) {
>               const xc_error *error = xc_get_last_error(xch);
>               if (error->code == XC_ERROR_NONE)
> -                     snprintf(error_str, ERROR_STRLEN, "%d: %s", errno, 
> strerror(errno));
> +                     snprintf(error_str, sizeof(error_str),
> +                              "%d: %s", errno, strerror(errno));
>               else
> -                     snprintf(error_str, ERROR_STRLEN, "%d: %s: %s",
> -                              error->code,
> +                     snprintf(error_str, sizeof(error_str),
> +                              "%d: %s: %s", error->code,
>                                xc_error_code_to_desc(error->code),
>                                error->message);
>       } else {
> -             snprintf(error_str, ERROR_STRLEN, "Unable to open XC 
> interface");
> +             snprintf(error_str, sizeof(error_str),
> +                      "Unable to open XC interface");
>       }
>       caml_raise_with_string(*caml_named_value("xc.error"), error_str);
> }
> -- 
> 1.7.10.4
> 
> 
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> Xen-devel@xxxxxxxxxxxxx
> http://lists.xen.org/xen-devel


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