/* Memory mapping wrappers.
 * ARM and MinGW ports contributed by Hideo Okuma and Tomoyuki Yoshimura at
 * NICT.
 */
#include "util/mmap.hh"

#include "util/exception.hh"
#include "util/file.hh"

#include <iostream>

#include <assert.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdlib.h>

#if defined(_WIN32) || defined(_WIN64)
#include <windows.h>
#include <io.h>
#else
#include <sys/mman.h>
#endif

namespace util {

long SizePage() {
#if defined(_WIN32) || defined(_WIN64)
  SYSTEM_INFO si;
  GetSystemInfo(&si);
  return si.dwAllocationGranularity;
#else
  return sysconf(_SC_PAGE_SIZE);
#endif
}

void SyncOrThrow(void *start, size_t length) {
#if defined(_WIN32) || defined(_WIN64)
  UTIL_THROW_IF(!::FlushViewOfFile(start, length), ErrnoException, "Failed to sync mmap");
#else
  UTIL_THROW_IF(msync(start, length, MS_SYNC), ErrnoException, "Failed to sync mmap");
#endif
}

void UnmapOrThrow(void *start, size_t length) {
#if defined(_WIN32) || defined(_WIN64)
  UTIL_THROW_IF(!::UnmapViewOfFile(start), ErrnoException, "Failed to unmap a file");
#else
  UTIL_THROW_IF(munmap(start, length), ErrnoException, "munmap failed");
#endif
}

scoped_mmap::~scoped_mmap() {
  if (data_ != (void*)-1) {
    try {
      // Thanks Denis Filimonov for pointing out NFS likes msync first.  
      SyncOrThrow(data_, size_);
      UnmapOrThrow(data_, size_);
    } catch (const util::ErrnoException &e) {
      std::cerr << e.what();
      abort();
    }
  }
}

void scoped_memory::reset(void *data, std::size_t size, Alloc source) {
  switch(source_) {
    case MMAP_ALLOCATED:
      scoped_mmap(data_, size_);
      break;
    case ARRAY_ALLOCATED:
      delete [] reinterpret_cast<char*>(data_);
      break;
    case MALLOC_ALLOCATED:
      free(data_);
      break;
    case NONE_ALLOCATED:
      break;
  }
  data_ = data;
  size_ = size;
  source_ = source;
}

void scoped_memory::call_realloc(std::size_t size) {
  assert(source_ == MALLOC_ALLOCATED || source_ == NONE_ALLOCATED);
  void *new_data = realloc(data_, size);
  if (!new_data) {
    reset();
  } else {
    reset(new_data, size, MALLOC_ALLOCATED);
  }
}

void *MapOrThrow(std::size_t size, bool for_write, int flags, bool prefault, int fd, uint64_t offset) {
#ifdef MAP_POPULATE // Linux specific
  if (prefault) {
    flags |= MAP_POPULATE;
  }
#endif
#if defined(_WIN32) || defined(_WIN64)
  int protectC = for_write ? PAGE_READWRITE : PAGE_READONLY;
  int protectM = for_write ? FILE_MAP_WRITE : FILE_MAP_READ;
  HANDLE hMapping = CreateFileMapping((HANDLE)_get_osfhandle(fd), NULL, protectC, 0, size + offset, NULL);
  UTIL_THROW_IF(!hMapping, ErrnoException, "CreateFileMapping failed");
  LPVOID ret = MapViewOfFile(hMapping, protectM, 0, offset, size);
  CloseHandle(hMapping);
  UTIL_THROW_IF(!ret, ErrnoException, "MapViewOfFile failed");
#else
  int protect = for_write ? (PROT_READ | PROT_WRITE) : PROT_READ;
  void *ret = mmap(NULL, size, protect, flags, fd, offset);
  UTIL_THROW_IF(ret == MAP_FAILED, ErrnoException, "mmap failed for size " << size << " at offset " << offset);
#endif
  return ret;
}

const int kFileFlags =
#if defined(_WIN32) || defined(_WIN64)
  0 // MapOrThrow ignores flags on windows
#elif defined(MAP_FILE)
  MAP_FILE | MAP_SHARED
#else
  MAP_SHARED
#endif
  ;

void MapRead(LoadMethod method, int fd, uint64_t offset, std::size_t size, scoped_memory &out) {
  switch (method) {
    case LAZY:
      out.reset(MapOrThrow(size, false, kFileFlags, false, fd, offset), size, scoped_memory::MMAP_ALLOCATED);
      break;
    case POPULATE_OR_LAZY:
#ifdef MAP_POPULATE
    case POPULATE_OR_READ:
#endif
      out.reset(MapOrThrow(size, false, kFileFlags, true, fd, offset), size, scoped_memory::MMAP_ALLOCATED);
      break;
#ifndef MAP_POPULATE
    case POPULATE_OR_READ:
#endif
    case READ:
      out.reset(malloc(size), size, scoped_memory::MALLOC_ALLOCATED);
      if (!out.get()) UTIL_THROW(util::ErrnoException, "Allocating " << size << " bytes with malloc");
      SeekOrThrow(fd, offset);
      ReadOrThrow(fd, out.get(), size);
      break;
  }
}

void *MapAnonymous(std::size_t size) {
  return MapOrThrow(size, true,
#if defined(_WIN32) || defined(_WIN64)
      0 // MapOrThrow ignores the flags anyway.
#elif defined(MAP_ANONYMOUS)
      MAP_ANONYMOUS | MAP_PRIVATE // Linux
#else
      MAP_ANON | MAP_PRIVATE // BSD
#endif
      , false, -1, 0);
}

void *MapZeroedWrite(int fd, std::size_t size) {
  ResizeOrThrow(fd, 0);
  ResizeOrThrow(fd, size);
  return MapOrThrow(size, true, kFileFlags, false, fd, 0);
}

namespace {

int CreateOrThrow(const char *name) {
  int ret;
#if defined(_WIN32) || defined(_WIN64)
  UTIL_THROW_IF(-1 == (ret = _open(name, _O_CREAT | _O_TRUNC | _O_RDWR, _S_IREAD | _S_IWRITE)), ErrnoException, "while creating " << name);
#else
  UTIL_THROW_IF(-1 == (ret = open(name, O_CREAT | O_TRUNC | O_RDWR, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)), ErrnoException, "while creating " << name);
#endif
  return ret;
}

} // namespace

void *MapZeroedWrite(const char *name, std::size_t size, scoped_fd &file) {
  file.reset(CreateOrThrow(name));
  try {
    return MapZeroedWrite(file.get(), size);
  } catch (ErrnoException &e) {
    e << " in file " << name;
    throw;
  }
}

} // namespace util