Re: [libiberty] does anyone use regex.c with REGEX_MALLOC?

[Aldy Hernandez]

On 07/23/2016 06:33 AM, Aldy Hernandez wrote:

If the REGEX_MALLOC mode in regex.c is unused, can I rip it out?  I'd
like to replace it all with alloca with a malloc fallback.

And yes, I realize regex.c already does this most of the time:


      if (size1 > MAX_ALLOCA_SIZE)
        {
          wcs_string1 = TALLOC (size1 + 1, CHAR_T);
          mbs_offset1 = TALLOC (size1 + 1, int);
          is_binary = TALLOC (size1 + 1, char);
        }
      else
        {
          wcs_string1 = REGEX_TALLOC (size1 + 1, CHAR_T);
          mbs_offset1 = REGEX_TALLOC (size1 + 1, int);
          is_binary = REGEX_TALLOC (size1 + 1, char);
        }

But there are other uses of REGEX_TALLOC that seem to call alloca() 
without any bound checks (where REGEX_TALLOC can be defined as alloca):

  if (bufp->re_nsub)
    {
      regstart = REGEX_TALLOC (num_regs, const CHAR_T *);
      regend = REGEX_TALLOC (num_regs, const CHAR_T *);
      ...
      ...
    }

and:

      if (csize1 != 0)
        {
          string1 = REGEX_TALLOC (csize1 + 1, CHAR_T);
          mbs_offset1 = REGEX_TALLOC (csize1 + 1, int);
          is_binary = REGEX_TALLOC (csize1 + 1, char);
          ...
        }

etc etc.

Cheerios.
Aldy