text: //===-- sanitizer_libc.cc -------------------------------------------------===//
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // This file is shared between AddressSanitizer and ThreadSanitizer
  // run-time libraries. See sanitizer_libc.h for details.
  //===----------------------------------------------------------------------===//
  
  #include "sanitizer_allocator_internal.h"
  #include "sanitizer_common.h"
  #include "sanitizer_libc.h"
  
  namespace __sanitizer {
  
  s64 internal_atoll(const char *nptr) {
    return internal_simple_strtoll(nptr, nullptr, 10);
  }
  
  void *internal_memchr(const void *s, int c, uptr n) {
    const char *t = (const char *)s;
    for (uptr i = 0; i < n; ++i, ++t)
      if (*t == c)
        return reinterpret_cast<void *>(const_cast<char *>(t));
    return nullptr;
  }
  
  void *internal_memrchr(const void *s, int c, uptr n) {
    const char *t = (const char *)s;
    void *res = nullptr;
    for (uptr i = 0; i < n; ++i, ++t) {
      if (*t == c) res = reinterpret_cast<void *>(const_cast<char *>(t));
    }
    return res;
  }
  
  int internal_memcmp(const void* s1, const void* s2, uptr n) {
    const char *t1 = (const char *)s1;
    const char *t2 = (const char *)s2;
    for (uptr i = 0; i < n; ++i, ++t1, ++t2)
      if (*t1 != *t2)
        return *t1 < *t2 ? -1 : 1;
    return 0;
  }
  
  void *internal_memcpy(void *dest, const void *src, uptr n) {
    char *d = (char*)dest;
    const char *s = (const char *)src;
    for (uptr i = 0; i < n; ++i)
      d[i] = s[i];
    return dest;
  }
  
  void *internal_memmove(void *dest, const void *src, uptr n) {
    char *d = (char*)dest;
    const char *s = (const char *)src;
    sptr i, signed_n = (sptr)n;
    CHECK_GE(signed_n, 0);
    if (d < s) {
      for (i = 0; i < signed_n; ++i)
        d[i] = s[i];
    } else {
      if (d > s && signed_n > 0)
        for (i = signed_n - 1; i >= 0 ; --i) {
          d[i] = s[i];
        }
    }
    return dest;
  }
  
  // Semi-fast bzero for 16-aligned data. Still far from peak performance.
  void internal_bzero_aligned16(void *s, uptr n) {
    struct ALIGNED(16) S16 { u64 a, b; };
    CHECK_EQ((reinterpret_cast<uptr>(s) | n) & 15, 0);
    for (S16 *p = reinterpret_cast<S16*>(s), *end = p + n / 16; p < end; p++) {
      p->a = p->b = 0;
      // Make sure this does not become memset.
      SanitizerBreakOptimization(nullptr);
    }
  }
  
  void *internal_memset(void* s, int c, uptr n) {
    // The next line prevents Clang from making a call to memset() instead of the
    // loop below.
    // FIXME: building the runtime with -ffreestanding is a better idea. However
    // there currently are linktime problems due to PR12396.
    char volatile *t = (char*)s;
    for (uptr i = 0; i < n; ++i, ++t) {
      *t = c;
    }
    return s;
  }
  
  uptr internal_strcspn(const char *s, const char *reject) {
    uptr i;
    for (i = 0; s[i]; i++) {
      if (internal_strchr(reject, s[i]))
        return i;
    }
    return i;
  }
  
  char* internal_strdup(const char *s) {
    uptr len = internal_strlen(s);
    char *s2 = (char*)InternalAlloc(len + 1);
    internal_memcpy(s2, s, len);
    s2[len] = 0;
    return s2;
  }
  
  char* internal_strndup(const char *s, uptr n) {
    uptr len = internal_strnlen(s, n);
    char *s2 = (char*)InternalAlloc(len + 1);
    internal_memcpy(s2, s, len);
    s2[len] = 0;
    return s2;
  }
  
  int internal_strcmp(const char *s1, const char *s2) {
    while (true) {
      unsigned c1 = *s1;
      unsigned c2 = *s2;
      if (c1 != c2) return (c1 < c2) ? -1 : 1;
      if (c1 == 0) break;
      s1++;
      s2++;
    }
    return 0;
  }
  
  int internal_strncmp(const char *s1, const char *s2, uptr n) {
    for (uptr i = 0; i < n; i++) {
      unsigned c1 = *s1;
      unsigned c2 = *s2;
      if (c1 != c2) return (c1 < c2) ? -1 : 1;
      if (c1 == 0) break;
      s1++;
      s2++;
    }
    return 0;
  }
  
  char* internal_strchr(const char *s, int c) {
    while (true) {
      if (*s == (char)c)
        return const_cast<char *>(s);
      if (*s == 0)
        return nullptr;
      s++;
    }
  }
  
  char *internal_strchrnul(const char *s, int c) {
    char *res = internal_strchr(s, c);
    if (!res)
      res = const_cast<char *>(s) + internal_strlen(s);
    return res;
  }
  
  char *internal_strrchr(const char *s, int c) {
    const char *res = nullptr;
    for (uptr i = 0; s[i]; i++) {
      if (s[i] == c) res = s + i;
    }
    return const_cast<char *>(res);
  }
  
  uptr internal_strlen(const char *s) {
    uptr i = 0;
    while (s[i]) i++;
    return i;
  }
  
  uptr internal_strlcat(char *dst, const char *src, uptr maxlen) {
    const uptr srclen = internal_strlen(src);
    const uptr dstlen = internal_strnlen(dst, maxlen);
    if (dstlen == maxlen) return maxlen + srclen;
    if (srclen < maxlen - dstlen) {
      internal_memmove(dst + dstlen, src, srclen + 1);
    } else {
      internal_memmove(dst + dstlen, src, maxlen - dstlen - 1);
      dst[maxlen - 1] = '\0';
    }
    return dstlen + srclen;
  }
  
  char *internal_strncat(char *dst, const char *src, uptr n) {
    uptr len = internal_strlen(dst);
    uptr i;
    for (i = 0; i < n && src[i]; i++)
      dst[len + i] = src[i];
    dst[len + i] = 0;
    return dst;
  }
  
  uptr internal_strlcpy(char *dst, const char *src, uptr maxlen) {
    const uptr srclen = internal_strlen(src);
    if (srclen < maxlen) {
      internal_memmove(dst, src, srclen + 1);
    } else if (maxlen != 0) {
      internal_memmove(dst, src, maxlen - 1);
      dst[maxlen - 1] = '\0';
    }
    return srclen;
  }
  
  char *internal_strncpy(char *dst, const char *src, uptr n) {
    uptr i;
    for (i = 0; i < n && src[i]; i++)
      dst[i] = src[i];
    internal_memset(dst + i, '\0', n - i);
    return dst;
  }
  
  uptr internal_strnlen(const char *s, uptr maxlen) {
    uptr i = 0;
    while (i < maxlen && s[i]) i++;
    return i;
  }
  
  char *internal_strstr(const char *haystack, const char *needle) {
    // This is O(N^2), but we are not using it in hot places.
    uptr len1 = internal_strlen(haystack);
    uptr len2 = internal_strlen(needle);
    if (len1 < len2) return nullptr;
    for (uptr pos = 0; pos <= len1 - len2; pos++) {
      if (internal_memcmp(haystack + pos, needle, len2) == 0)
        return const_cast<char *>(haystack) + pos;
    }
    return nullptr;
  }
  
  uptr internal_wcslen(const wchar_t *s) {
    uptr i = 0;
    while (s[i]) i++;
    return i;
  }
  
  s64 internal_simple_strtoll(const char *nptr, char **endptr, int base) {
    CHECK_EQ(base, 10);
    while (IsSpace(*nptr)) nptr++;
    int sgn = 1;
    u64 res = 0;
    bool have_digits = false;
    char *old_nptr = const_cast<char *>(nptr);
    if (*nptr == '+') {
      sgn = 1;
      nptr++;
    } else if (*nptr == '-') {
      sgn = -1;
      nptr++;
    }
    while (IsDigit(*nptr)) {
      res = (res <= UINT64_MAX / 10) ? res * 10 : UINT64_MAX;
      int digit = ((*nptr) - '0');
      res = (res <= UINT64_MAX - digit) ? res + digit : UINT64_MAX;
      have_digits = true;
      nptr++;
    }
    if (endptr) {
      *endptr = (have_digits) ? const_cast<char *>(nptr) : old_nptr;
    }
    if (sgn > 0) {
      return (s64)(Min((u64)INT64_MAX, res));
    } else {
      return (res > INT64_MAX) ? INT64_MIN : ((s64)res * -1);
    }
  }
  
  bool mem_is_zero(const char *beg, uptr size) {
    CHECK_LE(size, 1ULL << FIRST_32_SECOND_64(30, 40));  // Sanity check.
    const char *end = beg + size;
    uptr *aligned_beg = (uptr *)RoundUpTo((uptr)beg, sizeof(uptr));
    uptr *aligned_end = (uptr *)RoundDownTo((uptr)end, sizeof(uptr));
    uptr all = 0;
    // Prologue.
    for (const char *mem = beg; mem < (char*)aligned_beg && mem < end; mem++)
      all |= *mem;
    // Aligned loop.
    for (; aligned_beg < aligned_end; aligned_beg++)
      all |= *aligned_beg;
    // Epilogue.
    if ((char*)aligned_end >= beg)
      for (const char *mem = (char*)aligned_end; mem < end; mem++)
        all |= *mem;
    return all == 0;
  }
  
  } // namespace __sanitizer
  