#include <errno.h>
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>

#include "stdio_impl.h"

ssize_t getdelim(char **restrict s, size_t *restrict n, int delim, FILE *restrict f) {
  char *tmp;
  unsigned char *z;
  size_t k;
  size_t i = 0;
  int c;

  FLOCK(f);

  if (!n || !s) {
    f->mode |= f->mode - 1;
    f->flags |= F_ERR;
    FUNLOCK(f);
    errno = EINVAL;
    return -1;
  }

  if (!*s)
    *n = 0;

  for (;;) {
    if (f->rpos != f->rend) {
      z = memchr(f->rpos, delim, f->rend - f->rpos);
      k = z ? z - f->rpos + 1 : f->rend - f->rpos;
    } else {
      z = 0;
      k = 0;
    }
    if (i + k >= *n) {
      size_t m = i + k + 2;
      if (!z && m < SIZE_MAX / 4)
        m += m / 2;
      tmp = realloc(*s, m);
      if (!tmp) {
        m = i + k + 2;
        tmp = realloc(*s, m);
        if (!tmp) {
          /* Copy as much as fits and ensure no
           * pushback remains in the FILE buf. */
          k = *n - i;
          memcpy(*s + i, f->rpos, k);
          f->rpos += k;
          f->mode |= f->mode - 1;
          f->flags |= F_ERR;
          FUNLOCK(f);
          errno = ENOMEM;
          return -1;
        }
      }
      *s = tmp;
      *n = m;
    }
    if (k) {
      memcpy(*s + i, f->rpos, k);
      f->rpos += k;
      i += k;
    }
    if (z)
      break;
    if ((c = getc_unlocked(f)) == EOF) {
      if (!i || !feof(f)) {
        FUNLOCK(f);
        return -1;
      }
      break;
    }
    /* If the byte read by getc won't fit without growing the
     * output buffer, push it back for next iteration. */
    if (i + 1 >= *n)
      *--f->rpos = c;
    else if (((*s)[i++] = c) == delim)
      break;
  }
  (*s)[i] = 0;

  FUNLOCK(f);

  return i;
}

weak_alias(getdelim, __getdelim);