Re: [PATCH 2/2] libxl: Compile regular expression where it is used

[Jim Fehlig <jfehlig@xxxxxxxx>]

Jim Fehlig wrote:
> The regular expression used to determine guest capabilities
> was compiled in libxlCapsInitHost() but used in libxlCapsInitGuests().
> Move compilation to libxlCapsInitGuests() where it is used, and free
> the compiled regex after use.  Ensure not to free the regex if
> compilation fails.
>
> Signed-off-by: Jim Fehlig <jfehlig@xxxxxxxx>
> ---
>  src/libxl/libxl_conf.c | 29 +++++++++++++++--------------
>  1 file changed, 15 insertions(+), 14 deletions(-)
>
> diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
> index fcb278b..c7be7aa 100644
> --- a/src/libxl/libxl_conf.c
> +++ b/src/libxl/libxl_conf.c
> @@ -61,8 +61,7 @@ struct guest_arch {
>      int ia64_be;
>  };
>  
> -static const char *xen_cap_re = "(xen|hvm)-[[:digit:]]+\\.[[:digit:]]+-(x86_32|x86_64|ia64|powerpc64)(p|be)?";
> -static regex_t xen_cap_rec;
> +#define XEN_CAP_REGEX "(xen|hvm)-[[:digit:]]+\\.[[:digit:]]+-(x86_32|x86_64|ia64|powerpc64)(p|be)?";
>   

Opps, that's not quite right.  The version I actually compiled and
tested doesn't have the trailing ';' on the #define :).

Regards,
Jim

>  
>  
>  static virClassPtr libxlDriverConfigClass;
> @@ -103,20 +102,9 @@ libxlDriverConfigDispose(void *obj)
>  static int
>  libxlCapsInitHost(libxl_ctx *ctx, virCapsPtr caps)
>  {
> -    int err;
>      libxl_physinfo phy_info;
>      int host_pae;
>  
> -    err = regcomp(&xen_cap_rec, xen_cap_re, REG_EXTENDED);
> -    if (err != 0) {
> -        char error[100];
> -        regerror(err, &xen_cap_rec, error, sizeof(error));
> -        regfree(&xen_cap_rec);
> -        virReportError(VIR_ERR_INTERNAL_ERROR,
> -                       _("Failed to compile regex %s"), error);
> -        return -1;
> -    }
> -
>      if (libxl_get_physinfo(ctx, &phy_info) != 0) {
>          virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>                         _("Failed to get node physical info from libxenlight"));
> @@ -249,6 +237,8 @@ static int
>  libxlCapsInitGuests(libxl_ctx *ctx, virCapsPtr caps)
>  {
>      const libxl_version_info *ver_info;
> +    int err;
> +    regex_t regex;
>      char *str, *token;
>      regmatch_t subs[4];
>      char *saveptr = NULL;
> @@ -265,6 +255,16 @@ libxlCapsInitGuests(libxl_ctx *ctx, virCapsPtr caps)
>                         _("Failed to get version info from libxenlight"));
>          return -1;
>      }
> +
> +    err = regcomp(&regex, XEN_CAP_REGEX, REG_EXTENDED);
> +    if (err != 0) {
> +        char error[100];
> +        regerror(err, &regex, error, sizeof(error));
> +        virReportError(VIR_ERR_INTERNAL_ERROR,
> +                       _("Failed to compile regex %s"), error);
> +        return -1;
> +    }
> +
>      /* Format of capabilities string is documented in the code in
>       * xen-unstable.hg/xen/arch/.../setup.c.
>       *
> @@ -294,7 +294,7 @@ libxlCapsInitGuests(libxl_ctx *ctx, virCapsPtr caps)
>           nr_guest_archs < sizeof(guest_archs) / sizeof(guest_archs[0])
>                   && (token = strtok_r(str, " ", &saveptr)) != NULL;
>           str = NULL) {
> -        if (regexec(&xen_cap_rec, token, sizeof(subs) / sizeof(subs[0]),
> +        if (regexec(&regex, token, sizeof(subs) / sizeof(subs[0]),
>                      subs, 0) == 0) {
>              int hvm = STRPREFIX(&token[subs[1].rm_so], "hvm");
>              virArch arch;
> @@ -353,6 +353,7 @@ libxlCapsInitGuests(libxl_ctx *ctx, virCapsPtr caps)
>                  guest_archs[i].ia64_be = ia64_be;
>          }
>      }
> +    regfree(&regex);
>  
>      for (i = 0; i < nr_guest_archs; ++i) {
>          virCapsGuestPtr guest;
>   

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