metaforce/hecl/lib/winsupport.cpp

#include <cstdlib>
#include <cstdint>
#include <cstring>
#include <string>
#include "hecl/winsupport.hpp"

/*
 * The memmem() function finds the start of the first occurrence of the
 * substring 'needle' of length 'nlen' in the memory area 'haystack' of
 * length 'hlen'.
 *
 * The return value is a pointer to the beginning of the sub-string, or
 * NULL if the substring is not found.
 */
void* memmem(const void* haystack, size_t hlen, const void* needle, size_t nlen) {
  int needle_first;
  const uint8_t* p = static_cast<const uint8_t*>(haystack);
  size_t plen = hlen;

  if (!nlen)
    return NULL;

  needle_first = *(unsigned char*)needle;

  while (plen >= nlen && (p = static_cast<const uint8_t*>(memchr(p, needle_first, plen - nlen + 1)))) {
    if (!memcmp(p, needle, nlen))
      return (void*)p;

    p++;
    plen = hlen - (p - static_cast<const uint8_t*>(haystack));
  }

  return NULL;
}

int asprintf(char** buf, const char* format, ...) {
  va_list ap;
  va_start(ap, format);
  int len = vsnprintf(nullptr, 0, format, ap);
  va_end(ap);
  *buf = (char*)malloc(len + 1);
  va_start(ap, format);
  vsnprintf(*buf, len + 1, format, ap);
  va_end(ap);
  return len;
}