Stubs.cpp

//===--- Stubs.cpp - Swift Language ABI Runtime Stubs ---------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// Misc stubs for functions which should be defined in the core standard
// library, but are difficult or impossible to write in Swift at the
// moment.
//
//===----------------------------------------------------------------------===//

#if defined(__FreeBSD__)
#define _WITH_GETLINE
#endif

#include <sys/resource.h>
#include <sys/errno.h>
#include <unistd.h>
#include <climits>
#include <cstdarg>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <xlocale.h>
#include <limits>
#include "llvm/ADT/StringExtras.h"
#include "swift/Runtime/Debug.h"
#include "swift/Basic/Lazy.h"

static uint64_t uint64ToStringImpl(char *Buffer, uint64_t Value,
                                   int64_t Radix, bool Uppercase,
                                   bool Negative) {
  char *P = Buffer;
  uint64_t Y = Value;

  if (Y == 0) {
    *P++ = '0';
  } else if (Radix == 10) {
    while (Y) {
      *P++ = '0' + char(Y % 10);
      Y /= 10;
    }
  } else {
    unsigned Radix32 = Radix;
    while (Y) {
      *P++ = llvm::hexdigit(Y % Radix32, !Uppercase);
      Y /= Radix32;
    }
  }

  if (Negative)
    *P++ = '-';
  std::reverse(Buffer, P);
  return size_t(P - Buffer);
}

extern "C" uint64_t swift_int64ToString(char *Buffer, size_t BufferLength,
                                        int64_t Value, int64_t Radix,
                                        bool Uppercase) {
  if ((Radix >= 10 && BufferLength < 32) || (Radix < 10 && BufferLength < 65))
    swift::crash("swift_int64ToString: insufficient buffer size");

  if (Radix == 0 || Radix > 36)
    swift::crash("swift_int64ToString: invalid radix for string conversion");

  bool Negative = Value < 0;

  // Compute an absolute value safely, without using unary negation on INT_MIN,
  // which is undefined behavior.
  uint64_t UnsignedValue = Value;
  if (Negative) {
    // Assumes two's complement representation.
    UnsignedValue = ~UnsignedValue + 1;
  }

  return uint64ToStringImpl(Buffer, UnsignedValue, Radix, Uppercase,
                            Negative);
}

extern "C" uint64_t swift_uint64ToString(char *Buffer, intptr_t BufferLength,
                                         uint64_t Value, int64_t Radix,
                                         bool Uppercase) {
  if ((Radix >= 10 && BufferLength < 32) || (Radix < 10 && BufferLength < 64))
    swift::crash("swift_int64ToString: insufficient buffer size");

  if (Radix == 0 || Radix > 36)
    swift::crash("swift_int64ToString: invalid radix for string conversion");

  return uint64ToStringImpl(Buffer, Value, Radix, Uppercase,
                            /*Negative=*/false);
}

#if defined(__APPLE__) || defined(__FreeBSD__)
static inline locale_t getCLocale() {
  // On these platforms convenience functions from xlocale.h interpret nullptr
  // as C locale.
  return nullptr;
}
#else
static locale_t makeCLocale() {
  locale_t CLocale = newlocale(LC_ALL_MASK, "C", nullptr);
  if (!CLocale) {
    swift::crash("makeCLocale: newlocale() returned a null pointer");
  }
  return CLocale;
}

static locale_t getCLocale() {
  return SWIFT_LAZY_CONSTANT(makeCLocale());
}
#endif

#if defined(__APPLE__)
#define swift_snprintf_l snprintf_l
#else
static int swift_snprintf_l(char *Str, size_t StrSize, locale_t Locale,
                            const char *Format, ...) {
  if (Locale == nullptr) {
    Locale = getCLocale();
  }
  locale_t OldLocale = uselocale(Locale);

  va_list Args;
  va_start(Args, Format);
  int Result = std::vsnprintf(Str, StrSize, Format, Args);
  va_end(Args);

  uselocale(OldLocale);

  return Result;
}
#endif

template <typename T>
static uint64_t swift_floatingPointToString(char *Buffer, size_t BufferLength,
                                            T Value, const char *Format) {
  if (BufferLength < 32)
    swift::crash("swift_floatingPointToString: insufficient buffer size");

  const int Precision = std::numeric_limits<T>::digits10;

  // Pass a null locale to use the C locale.
  int i = swift_snprintf_l(Buffer, BufferLength, /*locale=*/nullptr, Format,
                           Precision, Value);

  if (i < 0)
    swift::crash(
        "swift_floatingPointToString: unexpected return value from sprintf");
  if (size_t(i) >= BufferLength)
    swift::crash("swift_floatingPointToString: insufficient buffer size");

  // Add ".0" to a float that (a) is not in scientific notation, (b) does not
  // already have a fractional part, (c) is not infinite, and (d) is not a NaN
  // value.
  if (strchr(Buffer, 'e') == nullptr && strchr(Buffer, '.') == nullptr &&
      strchr(Buffer, 'n') == nullptr) {
    Buffer[i++] = '.';
    Buffer[i++] = '0';
  }

  return i;
}

extern "C" uint64_t swift_float32ToString(char *Buffer, size_t BufferLength,
                                          float Value) {
  return swift_floatingPointToString<float>(Buffer, BufferLength, Value,
                                            "%0.*g");
}

extern "C" uint64_t swift_float64ToString(char *Buffer, size_t BufferLength,
                                          double Value) {
  return swift_floatingPointToString<double>(Buffer, BufferLength, Value,
                                             "%0.*g");
}

extern "C" uint64_t swift_float80ToString(char *Buffer, size_t BufferLength,
                                          long double Value) {
  return swift_floatingPointToString<long double>(Buffer, BufferLength, Value,
                                                  "%0.*Lg");
}

/// \param[out] LinePtr Replaced with the pointer to the malloc()-allocated
/// line.  Can be NULL if no characters were read.
///
/// \returns Size of character data returned in \c LinePtr, or -1
/// if an error occured, or EOF was reached.
extern "C" ssize_t swift_stdlib_readLine_stdin(char **LinePtr) {
  size_t Capacity = 0;
  return getline(LinePtr, &Capacity, stdin);
}

extern "C" float _swift_fmodf(float lhs, float rhs) {
    return fmodf(lhs, rhs);
}

extern "C" double _swift_fmod(double lhs, double rhs) {
    return fmod(lhs, rhs);
}

extern "C" long double _swift_fmodl(long double lhs, long double rhs) {
    return fmodl(lhs, rhs);
}


// Although this builtin is provided by clang rt builtins,
// it isn't provided by libgcc, which is the default
// runtime library on Linux, even when compiling with clang.
// This implementation is copied here to avoid a new dependency
// on compiler-rt on Linux.
// FIXME: rdar://14883575 Libcompiler_rt omits muloti4
#if __arm64__ || !defined(__APPLE__)

typedef int      ti_int __attribute__ ((mode (TI)));
extern "C"
ti_int
__muloti4(ti_int a, ti_int b, int* overflow)
{
    const int N = (int)(sizeof(ti_int) * CHAR_BIT);
    const ti_int MIN = (ti_int)1 << (N-1);
    const ti_int MAX = ~MIN;
    *overflow = 0;
    ti_int result = a * b;
    if (a == MIN)
    {
        if (b != 0 && b != 1)
	    *overflow = 1;
	return result;
    }
    if (b == MIN)
    {
        if (a != 0 && a != 1)
	    *overflow = 1;
        return result;
    }
    ti_int sa = a >> (N - 1);
    ti_int abs_a = (a ^ sa) - sa;
    ti_int sb = b >> (N - 1);
    ti_int abs_b = (b ^ sb) - sb;
    if (abs_a < 2 || abs_b < 2)
        return result;
    if (sa == sb)
    {
        if (abs_a > MAX / abs_b)
            *overflow = 1;
    }
    else
    {
        if (abs_a > MIN / -abs_b)
            *overflow = 1;
    }
    return result;
}

#endif

// We can't return Float80, but we can receive a pointer to one, so
// switch the return type and the out parameter on strtold.
template <typename T>
static const char *_swift_stdlib_strtoX_clocale_impl(
    const char * nptr, T* outResult, T huge,
    T (*posixImpl)(const char *, char **, locale_t)
) {
  char *EndPtr;
  errno = 0;
  const auto result = posixImpl(nptr, &EndPtr, getCLocale());
  *outResult = result;
  if (result == huge || result == -huge || result == 0.0 || result == -0.0) {
      if (errno == ERANGE)
          EndPtr = NULL;
  }
  return EndPtr;
}
    
extern "C" const char *_swift_stdlib_strtold_clocale(
  const char * nptr, void *outResult) {
  return _swift_stdlib_strtoX_clocale_impl(
    nptr, static_cast<long double*>(outResult), HUGE_VALL, strtold_l);
}

extern "C" const char *_swift_stdlib_strtod_clocale(
    const char * nptr, double *outResult) {
  return _swift_stdlib_strtoX_clocale_impl(
    nptr, outResult, HUGE_VAL, strtod_l);
}

extern "C" const char *_swift_stdlib_strtof_clocale(
    const char * nptr, float *outResult) {
  return _swift_stdlib_strtoX_clocale_impl(
    nptr, outResult, HUGE_VALF, strtof_l);
}

extern "C" void _swift_stdlib_flockfile_stdout() {
  flockfile(stdout);
}

extern "C" void _swift_stdlib_funlockfile_stdout() {
  funlockfile(stdout);
}

extern "C" int _swift_stdlib_putc_stderr(int C) {
  return putc(C, stderr);
}

extern "C" size_t _swift_stdlib_getHardwareConcurrency() {
  return sysconf(_SC_NPROCESSORS_ONLN);
}