//===- Unix/Process.cpp - Unix Process Implementation --------- -*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file provides the generic Unix implementation of the Process class.

//

//===----------------------------------------------------------------------===//

#include "Unix.h"

#include "llvm/ADT/Hashing.h"

#include "llvm/ADT/StringRef.h"

#include "llvm/Config/config.h"

#include "llvm/Support/ManagedStatic.h"

#include <mutex>

#if HAVE_FCNTL_H

#include <fcntl.h>

#endif

#ifdef HAVE_SYS_TIME_H

#include <sys/time.h>

#endif

#ifdef HAVE_SYS_RESOURCE_H

#include <sys/resource.h>

#endif

#ifdef HAVE_SYS_STAT_H

#include <sys/stat.h>

#endif

#if HAVE_SIGNAL_H

#include <signal.h>

#endif

#if defined(HAVE_MALLINFO)

#include <malloc.h>

#endif

#if defined(HAVE_MALLCTL)

#include <malloc_np.h>

#endif

#ifdef HAVE_MALLOC_MALLOC_H

#include <malloc/malloc.h>

#endif

#ifdef HAVE_SYS_IOCTL_H

#  include <sys/ioctl.h>

#endif

#ifdef HAVE_TERMIOS_H

#  include <termios.h>

#endif

//===----------------------------------------------------------------------===//

//=== WARNING: Implementation here must contain only generic UNIX code that

//===          is guaranteed to work on *all* UNIX variants.

//===----------------------------------------------------------------------===//

using namespace llvm;

using namespace sys;

static std::pair<std::chrono::microseconds, std::chrono::microseconds> getRUsageTimes() {

#if defined(HAVE_GETRUSAGE)

  struct rusage RU;

  ::getrusage(RUSAGE_SELF, &RU);

  return { toDuration(RU.ru_utime), toDuration(RU.ru_stime) };

#else

#warning Cannot get usage times on this platform

  return { std::chrono::microseconds::zero(), std::chrono::microseconds::zero() };

#endif

}

Process::Pid Process::getProcessId() {

  static_assert(sizeof(Pid) >= sizeof(pid_t),

                "Process::Pid should be big enough to store pid_t");

  return Pid(::getpid());

}

// On Cygwin, getpagesize() returns 64k(AllocationGranularity) and

// offset in mmap(3) should be aligned to the AllocationGranularity.

Expected<unsigned> Process::getPageSize() {

#if defined(HAVE_GETPAGESIZE)

  static const int page_size = ::getpagesize();

#elif defined(HAVE_SYSCONF)

  static long page_size = ::sysconf(_SC_PAGE_SIZE);

#else

#error Cannot get the page size on this machine

#endif

  if (page_size == -1)

    return errorCodeToError(std::error_code(errno, std::generic_category()));

  return static_cast<unsigned>(page_size);

}

size_t Process::GetMallocUsage() {

#if defined(HAVE_MALLINFO)

  struct mallinfo mi;

  mi = ::mallinfo();

  return mi.uordblks;

#elif defined(HAVE_MALLOC_ZONE_STATISTICS) && defined(HAVE_MALLOC_MALLOC_H)

  malloc_statistics_t Stats;

  malloc_zone_statistics(malloc_default_zone(), &Stats);

  return Stats.size_in_use;   // darwin

#elif defined(HAVE_MALLCTL)

  size_t alloc, sz;

  sz = sizeof(size_t);

  if (mallctl("stats.allocated", &alloc, &sz, NULL, 0) == 0)

    return alloc;

  return 0;

#elif defined(HAVE_SBRK)

  // Note this is only an approximation and more closely resembles

  // the value returned by mallinfo in the arena field.

  static char *StartOfMemory = reinterpret_cast<char*>(::sbrk(0));

  char *EndOfMemory = (char*)sbrk(0);

  if (EndOfMemory != ((char*)-1) && StartOfMemory != ((char*)-1))

    return EndOfMemory - StartOfMemory;

  return 0;

#else

#warning Cannot get malloc info on this platform

  return 0;

#endif

}

void Process::GetTimeUsage(TimePoint<> &elapsed, std::chrono::nanoseconds &user_time,

                           std::chrono::nanoseconds &sys_time) {

  elapsed = std::chrono::system_clock::now();

  std::tie(user_time, sys_time) = getRUsageTimes();

}

#if defined(HAVE_MACH_MACH_H) && !defined(__GNU__)

#include <mach/mach.h>

#endif

// Some LLVM programs such as bugpoint produce core files as a normal part of

// their operation. To prevent the disk from filling up, this function

// does what's necessary to prevent their generation.

void Process::PreventCoreFiles() {

#if HAVE_SETRLIMIT

  struct rlimit rlim;

  rlim.rlim_cur = rlim.rlim_max = 0;

  setrlimit(RLIMIT_CORE, &rlim);

#endif

#if defined(HAVE_MACH_MACH_H) && !defined(__GNU__)

  // Disable crash reporting on Mac OS X 10.0-10.4

  // get information about the original set of exception ports for the task

  mach_msg_type_number_t Count = 0;

  exception_mask_t OriginalMasks[EXC_TYPES_COUNT];

  exception_port_t OriginalPorts[EXC_TYPES_COUNT];

  exception_behavior_t OriginalBehaviors[EXC_TYPES_COUNT];

  thread_state_flavor_t OriginalFlavors[EXC_TYPES_COUNT];

  kern_return_t err =

    task_get_exception_ports(mach_task_self(), EXC_MASK_ALL, OriginalMasks,

                             &Count, OriginalPorts, OriginalBehaviors,

                             OriginalFlavors);

  if (err == KERN_SUCCESS) {

    // replace each with MACH_PORT_NULL.

    for (unsigned i = 0; i != Count; ++i)

      task_set_exception_ports(mach_task_self(), OriginalMasks[i],

                               MACH_PORT_NULL, OriginalBehaviors[i],

                               OriginalFlavors[i]);

  }

  // Disable crash reporting on Mac OS X 10.5

  signal(SIGABRT, _exit);

  signal(SIGILL,  _exit);

  signal(SIGFPE,  _exit);

  signal(SIGSEGV, _exit);

  signal(SIGBUS,  _exit);

#endif

  coreFilesPrevented = true;

}

Optional<std::string> Process::GetEnv(StringRef Name) {

  std::string NameStr = Name.str();

  const char *Val = ::getenv(NameStr.c_str());

  if (!Val)

    return None;

  return std::string(Val);

}

namespace {

class FDCloser {

public:

  FDCloser(int &FD) : FD(FD), KeepOpen(false) {}

  void keepOpen() { KeepOpen = true; }

  ~FDCloser() {

    if (!KeepOpen && FD >= 0)

      ::close(FD);

  }

private:

  FDCloser(const FDCloser &) = delete;

  void operator=(const FDCloser &) = delete;

  int &FD;

  bool KeepOpen;

};

}

std::error_code Process::FixupStandardFileDescriptors() {

  int NullFD = -1;

  FDCloser FDC(NullFD);

  const int StandardFDs[] = {STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO};

  for (int StandardFD : StandardFDs) {

    struct stat st;

    errno = 0;

    if (RetryAfterSignal(-1, ::fstat, StandardFD, &st) < 0) {

      assert(errno && "expected errno to be set if fstat failed!");

      // fstat should return EBADF if the file descriptor is closed.

      if (errno != EBADF)

        return std::error_code(errno, std::generic_category());

    }

    // if fstat succeeds, move on to the next FD.

    if (!errno)

      continue;

    assert(errno == EBADF && "expected errno to have EBADF at this point!");

    if (NullFD < 0) {

      // Call ::open in a lambda to avoid overload resolution in

      // RetryAfterSignal when open is overloaded, such as in Bionic.

      auto Open = [&]() { return ::open("/dev/null", O_RDWR); };

      if ((NullFD = RetryAfterSignal(-1, Open)) < 0)

        return std::error_code(errno, std::generic_category());

    }

    if (NullFD == StandardFD)

      FDC.keepOpen();

    else if (dup2(NullFD, StandardFD) < 0)

      return std::error_code(errno, std::generic_category());

  }

  return std::error_code();

}

std::error_code Process::SafelyCloseFileDescriptor(int FD) {

  // Create a signal set filled with *all* signals.

  sigset_t FullSet;

  if (sigfillset(&FullSet) < 0)

    return std::error_code(errno, std::generic_category());

  // Atomically swap our current signal mask with a full mask.

  sigset_t SavedSet;

#if LLVM_ENABLE_THREADS

  if (int EC = pthread_sigmask(SIG_SETMASK, &FullSet, &SavedSet))

    return std::error_code(EC, std::generic_category());

#else

  if (sigprocmask(SIG_SETMASK, &FullSet, &SavedSet) < 0)

    return std::error_code(errno, std::generic_category());

#endif

  // Attempt to close the file descriptor.

  // We need to save the error, if one occurs, because our subsequent call to

  // pthread_sigmask might tamper with errno.

  int ErrnoFromClose = 0;

  if (::close(FD) < 0)

    ErrnoFromClose = errno;

  // Restore the signal mask back to what we saved earlier.

  int EC = 0;

#if LLVM_ENABLE_THREADS

  EC = pthread_sigmask(SIG_SETMASK, &SavedSet, nullptr);

#else

  if (sigprocmask(SIG_SETMASK, &SavedSet, nullptr) < 0)

    EC = errno;

#endif

  // The error code from close takes precedence over the one from

  // pthread_sigmask.

  if (ErrnoFromClose)

    return std::error_code(ErrnoFromClose, std::generic_category());

  return std::error_code(EC, std::generic_category());

}

bool Process::StandardInIsUserInput() {

  return FileDescriptorIsDisplayed(STDIN_FILENO);

}

bool Process::StandardOutIsDisplayed() {

  return FileDescriptorIsDisplayed(STDOUT_FILENO);

}

bool Process::StandardErrIsDisplayed() {

  return FileDescriptorIsDisplayed(STDERR_FILENO);

}

bool Process::FileDescriptorIsDisplayed(int fd) {

#if HAVE_ISATTY

  return isatty(fd);

#else

  // If we don't have isatty, just return false.

  return false;

#endif

}

static unsigned getColumns() {

  // If COLUMNS is defined in the environment, wrap to that many columns.

  if (const char *ColumnsStr = std::getenv("COLUMNS")) {

    int Columns = std::atoi(ColumnsStr);

    if (Columns > 0)

      return Columns;

  }

  // We used to call ioctl TIOCGWINSZ to determine the width. It is considered

  // unuseful.

  return 0;

}

unsigned Process::StandardOutColumns() {

  if (!StandardOutIsDisplayed())

    return 0;

  return getColumns();

}

unsigned Process::StandardErrColumns() {

  if (!StandardErrIsDisplayed())

    return 0;

  return getColumns();

}

#ifdef HAVE_TERMINFO

// We manually declare these extern functions because finding the correct

// headers from various terminfo, curses, or other sources is harder than

// writing their specs down.

extern "C" int setupterm(char *term, int filedes, int *errret);

extern "C" struct term *set_curterm(struct term *termp);

extern "C" int del_curterm(struct term *termp);

extern "C" int tigetnum(char *capname);

#endif

#ifdef HAVE_TERMINFO

static ManagedStatic<std::mutex> TermColorMutex;

#endif

static bool terminalHasColors(int fd) {

#ifdef HAVE_TERMINFO

  // First, acquire a global lock because these C routines are thread hostile.

  std::lock_guard<std::mutex> G(*TermColorMutex);

  int errret = 0;

  if (setupterm(nullptr, fd, &errret) != 0)

    // Regardless of why, if we can't get terminfo, we shouldn't try to print

    // colors.

    return false;

  // Test whether the terminal as set up supports color output. How to do this

  // isn't entirely obvious. We can use the curses routine 'has_colors' but it

  // would be nice to avoid a dependency on curses proper when we can make do

  // with a minimal terminfo parsing library. Also, we don't really care whether

  // the terminal supports the curses-specific color changing routines, merely

  // if it will interpret ANSI color escape codes in a reasonable way. Thus, the

  // strategy here is just to query the baseline colors capability and if it

  // supports colors at all to assume it will translate the escape codes into

  // whatever range of colors it does support. We can add more detailed tests

  // here if users report them as necessary.

  //

  // The 'tigetnum' routine returns -2 or -1 on errors, and might return 0 if

  // the terminfo says that no colors are supported.

  bool HasColors = tigetnum(const_cast<char *>("colors")) > 0;

  // Now extract the structure allocated by setupterm and free its memory

  // through a really silly dance.

  struct term *termp = set_curterm(nullptr);

  (void)del_curterm(termp); // Drop any errors here.

  // Return true if we found a color capabilities for the current terminal.

  if (HasColors)

    return true;

#else

  // When the terminfo database is not available, check if the current terminal

  // is one of terminals that are known to support ANSI color escape codes.

  if (const char *TermStr = std::getenv("TERM")) {

    return StringSwitch<bool>(TermStr)

      .Case("ansi", true)

      .Case("cygwin", true)

      .Case("linux", true)

      .StartsWith("screen", true)

      .StartsWith("xterm", true)

      .StartsWith("vt100", true)

      .StartsWith("rxvt", true)

      .EndsWith("color", true)

      .Default(false);

  }

#endif

  // Otherwise, be conservative.

  return false;

}

bool Process::FileDescriptorHasColors(int fd) {

  // A file descriptor has colors if it is displayed and the terminal has

  // colors.

  return FileDescriptorIsDisplayed(fd) && terminalHasColors(fd);

}

bool Process::StandardOutHasColors() {

  return FileDescriptorHasColors(STDOUT_FILENO);

}

bool Process::StandardErrHasColors() {

  return FileDescriptorHasColors(STDERR_FILENO);

}

void Process::UseANSIEscapeCodes(bool /*enable*/) {

  // No effect.

}

bool Process::ColorNeedsFlush() {

  // No, we use ANSI escape sequences.

  return false;

}

const char *Process::OutputColor(char code, bool bold, bool bg) {

  return colorcodes[bg?1:0][bold?1:0][code&7];

}

const char *Process::OutputBold(bool bg) {

  return "\033[1m";

}

const char *Process::OutputReverse() {

  return "\033[7m";

}

const char *Process::ResetColor() {

  return "\033[0m";

}

#if !HAVE_DECL_ARC4RANDOM

static unsigned GetRandomNumberSeed() {

  // Attempt to get the initial seed from /dev/urandom, if possible.

  int urandomFD = open("/dev/urandom", O_RDONLY);

  if (urandomFD != -1) {

    unsigned seed;

    // Don't use a buffered read to avoid reading more data

    // from /dev/urandom than we need.

    int count = read(urandomFD, (void *)&seed, sizeof(seed));

    close(urandomFD);

    // Return the seed if the read was successful.

    if (count == sizeof(seed))

      return seed;

  }

  // Otherwise, swizzle the current time and the process ID to form a reasonable

  // seed.

  const auto Now = std::chrono::high_resolution_clock::now();

  return hash_combine(Now.time_since_epoch().count(), ::getpid());

}

#endif

unsigned llvm::sys::Process::GetRandomNumber() {

#if HAVE_DECL_ARC4RANDOM

  return arc4random();

#else

  static int x = (static_cast<void>(::srand(GetRandomNumberSeed())), 0);

  (void)x;

  return ::rand();

#endif

}