// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Platform-specific code for Linux goes here. For the POSIX-compatible
// parts, the implementation is in platform-posix.cc.

#include <pthread.h>
#include <semaphore.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/syscall.h>
#include <sys/time.h>

// Ubuntu Dapper requires memory pages to be marked as
// executable. Otherwise, OS raises an exception when executing code
// in that page.
#include <errno.h>
#include <fcntl.h>  // open
#include <stdarg.h>
#include <strings.h>    // index
#include <sys/mman.h>   // mmap & munmap
#include <sys/stat.h>   // open
#include <sys/types.h>  // mmap & munmap
#include <unistd.h>     // sysconf

// GLibc on ARM defines mcontext_t has a typedef for 'struct sigcontext'.
// Old versions of the C library <signal.h> didn't define the type.
#if defined(__ANDROID__) && !defined(__BIONIC_HAVE_UCONTEXT_T) && \
    (defined(__arm__) || defined(__aarch64__)) &&                 \
    !defined(__BIONIC_HAVE_STRUCT_SIGCONTEXT)
#include <asm/sigcontext.h>  // NOLINT
#endif

#include <cmath>

#undef MAP_TYPE

#include "src/base/macros.h"
#include "src/base/platform/platform-posix-time.h"
#include "src/base/platform/platform-posix.h"
#include "src/base/platform/platform.h"

namespace v8 {
namespace base {

#ifdef __arm__

bool OS::ArmUsingHardFloat() {
// GCC versions 4.6 and above define __ARM_PCS or __ARM_PCS_VFP to specify
// the Floating Point ABI used (PCS stands for Procedure Call Standard).
// We use these as well as a couple of other defines to statically determine
// what FP ABI used.
// GCC versions 4.4 and below don't support hard-fp.
// GCC versions 4.5 may support hard-fp without defining __ARM_PCS or
// __ARM_PCS_VFP.

#define GCC_VERSION \
  (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__)
#if GCC_VERSION >= 40600 && !defined(__clang__)
#if defined(__ARM_PCS_VFP)
  return true;
#else
  return false;
#endif

#elif GCC_VERSION < 40500 && !defined(__clang__)
  return false;

#else
#if defined(__ARM_PCS_VFP)
  return true;
#elif defined(__ARM_PCS) || defined(__SOFTFP__) || defined(__SOFTFP) || \
    !defined(__VFP_FP__)
  return false;
#else
#error \
    "Your version of compiler does not report the FP ABI compiled for."     \
       "Please report it on this issue"                                        \
       "http://code.google.com/p/v8/issues/detail?id=2140"

#endif
#endif
#undef GCC_VERSION
}

#endif  // def __arm__

TimezoneCache* OS::CreateTimezoneCache() {
  return new PosixDefaultTimezoneCache();
}

// Constants used for mmap.
static const int kMmapFd = -1;
static const int kMmapFdOffset = 0;

void* OS::Allocate(const size_t requested, size_t* allocated,
                   OS::MemoryPermission access, void* hint) {
  const size_t msize = RoundUp(requested, AllocateAlignment());
  int prot = GetProtectionFromMemoryPermission(access);
  void* mbase = mmap(hint, msize, prot, MAP_PRIVATE | MAP_ANONYMOUS, kMmapFd,
                     kMmapFdOffset);
  if (mbase == MAP_FAILED) return nullptr;
  *allocated = msize;
  return mbase;
}

// static
void* OS::ReserveRegion(size_t size, void* hint) {
  void* result =
      mmap(hint, size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE,
           kMmapFd, kMmapFdOffset);

  if (result == MAP_FAILED) return nullptr;
  return result;
}

// static
void* OS::ReserveAlignedRegion(size_t size, size_t alignment, void* hint,
                               size_t* allocated) {
  DCHECK((alignment % OS::AllocateAlignment()) == 0);
  hint = AlignedAddress(hint, alignment);
  size_t request_size =
      RoundUp(size + alignment, static_cast<intptr_t>(OS::AllocateAlignment()));
  void* result = ReserveRegion(request_size, hint);
  if (result == nullptr) {
    *allocated = 0;
    return nullptr;
  }

  uint8_t* base = static_cast<uint8_t*>(result);
  uint8_t* aligned_base = RoundUp(base, alignment);
  DCHECK_LE(base, aligned_base);

  // Unmap extra memory reserved before and after the desired block.
  if (aligned_base != base) {
    size_t prefix_size = static_cast<size_t>(aligned_base - base);
    OS::Free(base, prefix_size);
    request_size -= prefix_size;
  }

  size_t aligned_size = RoundUp(size, OS::AllocateAlignment());
  DCHECK_LE(aligned_size, request_size);

  if (aligned_size != request_size) {
    size_t suffix_size = request_size - aligned_size;
    OS::Free(aligned_base + aligned_size, suffix_size);
    request_size -= suffix_size;
  }

  DCHECK(aligned_size == request_size);

  *allocated = aligned_size;
  return static_cast<void*>(aligned_base);
}

// static
bool OS::CommitRegion(void* address, size_t size, bool is_executable) {
  int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
  if (MAP_FAILED == mmap(address, size, prot,
                         MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, kMmapFd,
                         kMmapFdOffset)) {
    return false;
  }

  return true;
}

// static
bool OS::UncommitRegion(void* address, size_t size) {
  return mmap(address, size, PROT_NONE,
              MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE | MAP_FIXED, kMmapFd,
              kMmapFdOffset) != MAP_FAILED;
}

// static
bool OS::ReleaseRegion(void* address, size_t size) {
  return munmap(address, size) == 0;
}

// static
bool OS::ReleasePartialRegion(void* address, size_t size) {
  return munmap(address, size) == 0;
}

// static
bool OS::HasLazyCommits() { return true; }

std::vector<OS::SharedLibraryAddress> OS::GetSharedLibraryAddresses() {
  std::vector<SharedLibraryAddress> result;
  // This function assumes that the layout of the file is as follows:
  // hex_start_addr-hex_end_addr rwxp <unused data> [binary_file_name]
  // If we encounter an unexpected situation we abort scanning further entries.
  FILE* fp = fopen("/proc/self/maps", "r");
  if (fp == NULL) return result;

  // Allocate enough room to be able to store a full file name.
  const int kLibNameLen = FILENAME_MAX + 1;
  char* lib_name = reinterpret_cast<char*>(malloc(kLibNameLen));

  // This loop will terminate once the scanning hits an EOF.
  while (true) {
    uintptr_t start, end;
    char attr_r, attr_w, attr_x, attr_p;
    // Parse the addresses and permission bits at the beginning of the line.
    if (fscanf(fp, "%" V8PRIxPTR "-%" V8PRIxPTR, &start, &end) != 2) break;
    if (fscanf(fp, " %c%c%c%c", &attr_r, &attr_w, &attr_x, &attr_p) != 4) break;

    int c;
    if (attr_r == 'r' && attr_w != 'w' && attr_x == 'x') {
      // Found a read-only executable entry. Skip characters until we reach
      // the beginning of the filename or the end of the line.
      do {
        c = getc(fp);
      } while ((c != EOF) && (c != '\n') && (c != '/') && (c != '['));
      if (c == EOF) break;  // EOF: Was unexpected, just exit.

      // Process the filename if found.
      if ((c == '/') || (c == '[')) {
        // Push the '/' or '[' back into the stream to be read below.
        ungetc(c, fp);

        // Read to the end of the line. Exit if the read fails.
        if (fgets(lib_name, kLibNameLen, fp) == NULL) break;

        // Drop the newline character read by fgets. We do not need to check
        // for a zero-length string because we know that we at least read the
        // '/' or '[' character.
        lib_name[strlen(lib_name) - 1] = '\0';
      } else {
        // No library name found, just record the raw address range.
        snprintf(lib_name, kLibNameLen, "%08" V8PRIxPTR "-%08" V8PRIxPTR, start,
                 end);
      }
      result.push_back(SharedLibraryAddress(lib_name, start, end));
    } else {
      // Entry not describing executable data. Skip to end of line to set up
      // reading the next entry.
      do {
        c = getc(fp);
      } while ((c != EOF) && (c != '\n'));
      if (c == EOF) break;
    }
  }
  free(lib_name);
  fclose(fp);
  return result;
}

void OS::SignalCodeMovingGC(void* hint) {
  // Support for ll_prof.py.
  //
  // The Linux profiler built into the kernel logs all mmap's with
  // PROT_EXEC so that analysis tools can properly attribute ticks. We
  // do a mmap with a name known by ll_prof.py and immediately munmap
  // it. This injects a GC marker into the stream of events generated
  // by the kernel and allows us to synchronize V8 code log and the
  // kernel log.
  long size = sysconf(_SC_PAGESIZE);  // NOLINT(runtime/int)
  FILE* f = fopen(OS::GetGCFakeMMapFile(), "w+");
  if (f == NULL) {
    OS::PrintError("Failed to open %s\n", OS::GetGCFakeMMapFile());
    OS::Abort();
  }
  void* addr =
      mmap(hint, size, PROT_READ | PROT_EXEC, MAP_PRIVATE, fileno(f), 0);
  DCHECK_NE(MAP_FAILED, addr);
  OS::Free(addr, size);
  fclose(f);
}

}  // namespace base
}  // namespace v8