[libvirt] [PATCH 08/12] util: use GRegex in virCommandRunRegex

[Peter Krempa]

On Wed, Nov 13, 2019 at 16:48:49 +0100, Ján Tomko wrote:
> This saves us from allocating vars upfront, since GLib deals with
> that for us.
> 
> Signed-off-by: Ján Tomko <jtomko at redhat.com>
> ---
>  src/util/vircommand.c | 37 +++++++++++++------------------------
>  1 file changed, 13 insertions(+), 24 deletions(-)
> 
> diff --git a/src/util/vircommand.c b/src/util/vircommand.c
> index 49432ddfcb..1ab3dbc819 100644
> --- a/src/util/vircommand.c
> +++ b/src/util/vircommand.c
> @@ -22,7 +22,6 @@
>  #include <config.h>
>  
>  #include <poll.h>
> -#include <regex.h>
>  #include <signal.h>
>  #include <stdarg.h>
>  #include <sys/stat.h>
> @@ -3077,11 +3076,10 @@ virCommandRunRegex(virCommandPtr cmd,
>                     const char *prefix,
>                     int *exitstatus)
>  {
> -    int err;
> -    regex_t *reg;
> -    g_autofree regmatch_t *vars = NULL;
> +    GRegex **reg = NULL;
> +    g_autoptr(GMatchInfo) info = NULL;

This g_autoptr ...

>      size_t i, j, k;
> -    int totgroups = 0, ngroup = 0, maxvars = 0;
> +    int totgroups = 0, ngroup = 0;
>      char **groups;
>      g_autofree char *outbuf = NULL;
>      VIR_AUTOSTRINGLIST lines = NULL;
> @@ -3092,29 +3090,23 @@ virCommandRunRegex(virCommandPtr cmd,
>          return -1;
>  
>      for (i = 0; i < nregex; i++) {
> -        err = regcomp(&reg[i], regex[i], REG_EXTENDED);
> -        if (err != 0) {
> -            char error[100];
> -            regerror(err, &reg[i], error, sizeof(error));
> +        g_autoptr(GError) err = NULL;
> +        reg[i] = g_regex_new(regex[i], G_REGEX_OPTIMIZE, 0, &err);
> +        if (!reg[i]) {
>              virReportError(VIR_ERR_INTERNAL_ERROR,
> -                           _("Failed to compile regex %s"), error);
> +                           _("Failed to compile regex %s"), err->message);
>              for (j = 0; j < i; j++)
> -                regfree(&reg[j]);
> +                g_regex_unref(reg[j]);
>              VIR_FREE(reg);
>              return -1;
>          }
>  
>          totgroups += nvars[i];
> -        if (nvars[i] > maxvars)
> -            maxvars = nvars[i];
> -
>      }
>  
>      /* Storage for matched variables */
>      if (VIR_ALLOC_N(groups, totgroups) < 0)
>          goto cleanup;
> -    if (VIR_ALLOC_N(vars, maxvars+1) < 0)
> -        goto cleanup;
>  
>      virCommandSetOutputBuffer(cmd, &outbuf);
>      if (virCommandRun(cmd, exitstatus) < 0)
> @@ -3140,15 +3132,12 @@ virCommandRunRegex(virCommandPtr cmd,
>  
>          ngroup = 0;
>          for (i = 0; i < nregex; i++) {
> -            if (regexec(&reg[i], p, nvars[i]+1, vars, 0) != 0)
> +            if (!(g_regex_match(reg[i], p, 0, &info)))

... will not free the pointer returned here overwritten by the
iterating. The best will be to declare it just above.

>                  break;
>  
> -            /* NB vars[0] is the full pattern, so we offset j by 1 */
> -            for (j = 1; j <= nvars[i]; j++) {
> -                if (VIR_STRNDUP(groups[ngroup++], p + vars[j].rm_so,
> -                                vars[j].rm_eo - vars[j].rm_so) < 0)
> -                    goto cleanup;
> -            }
> +            /* NB match #0 is the full pattern, so we offset j by 1 */
> +            for (j = 1; j <= nvars[i]; j++)
> +                groups[ngroup++] = g_match_info_fetch(info, j);
>  
>          }
>          /* We've matched on the last regex, so callback time */
> @@ -3170,7 +3159,7 @@ virCommandRunRegex(virCommandPtr cmd,
>      }
>  
>      for (i = 0; i < nregex; i++)
> -        regfree(&reg[i]);
> +        g_regex_unref(reg[i]);
>  
>      VIR_FREE(reg);
>      return ret;

with the memleak fixed:

Reviewed-by: Peter Krempa <pkrempa at redhat.com>