cosmopolitan/tool/lambda/lib/calloc.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8                               :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/runtime/runtime.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/prot.h"

void *Calloc(size_t a, size_t b) {
  char *r;
  size_t z;
  static char *p;
  static size_t i;
  static size_t n;
  z = a * b;
  if (!p) {
    n = getgransize();
    p = mmap((void *)0x300000000000, getgransize(), PROT_READ | PROT_WRITE,
             MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
  }
  if (i + z > n) {
    mmap(p + i, getgransize(), PROT_READ | PROT_WRITE,
         MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
    n += getgransize();
  }
  r = p + i;
  i += z;
  return r;
}