[v2,3/5] regex: remove alloca usage on regex set_regs

  It syncs with gnulib version b6207ab38.  It replaces the regmatch_t
with a dynarray list.

Checked on x86_64-linux-gnu.
---
 posix/regexec.c | 40 ++++++++++++++++++----------------------
 1 file changed, 18 insertions(+), 22 deletions(-)
  

I will commit this shortly if no one opposes it.

On 13/01/2021 13:58, Adhemerval Zanella wrote:
> It syncs with gnulib version b6207ab38.  It replaces the regmatch_t
> with a dynarray list.
> 
> Checked on x86_64-linux-gnu.
> ---
>  posix/regexec.c | 40 ++++++++++++++++++----------------------
>  1 file changed, 18 insertions(+), 22 deletions(-)
> 
> diff --git a/posix/regexec.c b/posix/regexec.c
> index b083342f77..889b10be9c 100644
> --- a/posix/regexec.c
> +++ b/posix/regexec.c
> @@ -1355,6 +1355,12 @@ pop_fail_stack (struct re_fail_stack_t *fs, Idx *pidx, Idx nregs,
>    return fs->stack[num].node;
>  }
>  
> +
> +#define DYNARRAY_STRUCT  regmatch_list
> +#define DYNARRAY_ELEMENT regmatch_t
> +#define DYNARRAY_PREFIX  regmatch_list_
> +#include <malloc/dynarray-skeleton.c>
> +
>  /* Set the positions where the subexpressions are starts/ends to registers
>     PMATCH.
>     Note: We assume that pmatch[0] is already set, and
> @@ -1370,8 +1376,8 @@ set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch,
>    re_node_set eps_via_nodes;
>    struct re_fail_stack_t *fs;
>    struct re_fail_stack_t fs_body = { 0, 2, NULL };
> -  regmatch_t *prev_idx_match;
> -  bool prev_idx_match_malloced = false;
> +  struct regmatch_list prev_match;
> +  regmatch_list_init (&prev_match);
>  
>    DEBUG_ASSERT (nmatch > 1);
>    DEBUG_ASSERT (mctx->state_log != NULL);
> @@ -1388,18 +1394,13 @@ set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch,
>    cur_node = dfa->init_node;
>    re_node_set_init_empty (&eps_via_nodes);
>  
> -  if (__libc_use_alloca (nmatch * sizeof (regmatch_t)))
> -    prev_idx_match = (regmatch_t *) alloca (nmatch * sizeof (regmatch_t));
> -  else
> +  if (!regmatch_list_resize (&prev_match, nmatch))
>      {
> -      prev_idx_match = re_malloc (regmatch_t, nmatch);
> -      if (prev_idx_match == NULL)
> -	{
> -	  free_fail_stack_return (fs);
> -	  return REG_ESPACE;
> -	}
> -      prev_idx_match_malloced = true;
> +      regmatch_list_free (&prev_match);
> +      free_fail_stack_return (fs);
> +      return REG_ESPACE;
>      }
> +  regmatch_t *prev_idx_match = regmatch_list_begin (&prev_match);
>    memcpy (prev_idx_match, pmatch, sizeof (regmatch_t) * nmatch);
>  
>    for (idx = pmatch[0].rm_so; idx <= pmatch[0].rm_eo ;)
> @@ -1417,8 +1418,7 @@ set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch,
>  	      if (reg_idx == nmatch)
>  		{
>  		  re_node_set_free (&eps_via_nodes);
> -		  if (prev_idx_match_malloced)
> -		    re_free (prev_idx_match);
> +		  regmatch_list_free (&prev_match);
>  		  return free_fail_stack_return (fs);
>  		}
>  	      cur_node = pop_fail_stack (fs, &idx, nmatch, pmatch,
> @@ -1427,8 +1427,7 @@ set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch,
>  	  else
>  	    {
>  	      re_node_set_free (&eps_via_nodes);
> -	      if (prev_idx_match_malloced)
> -		re_free (prev_idx_match);
> +	      regmatch_list_free (&prev_match);
>  	      return REG_NOERROR;
>  	    }
>  	}
> @@ -1442,8 +1441,7 @@ set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch,
>  	  if (__glibc_unlikely (cur_node == -2))
>  	    {
>  	      re_node_set_free (&eps_via_nodes);
> -	      if (prev_idx_match_malloced)
> -		re_free (prev_idx_match);
> +	      regmatch_list_free (&prev_match);
>  	      free_fail_stack_return (fs);
>  	      return REG_ESPACE;
>  	    }
> @@ -1453,15 +1451,13 @@ set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch,
>  	  else
>  	    {
>  	      re_node_set_free (&eps_via_nodes);
> -	      if (prev_idx_match_malloced)
> -		re_free (prev_idx_match);
> +	      regmatch_list_free (&prev_match);
>  	      return REG_NOMATCH;
>  	    }
>  	}
>      }
>    re_node_set_free (&eps_via_nodes);
> -  if (prev_idx_match_malloced)
> -    re_free (prev_idx_match);
> +  regmatch_list_free (&prev_match);
>    return free_fail_stack_return (fs);
>  }
>  
>