summary refs log tree commit diff stats
path: root/doc/docgen_sample.nim
diff options
context:
space:
mode:
authorAraq <rumpf_a@web.de>2018-10-02 15:51:33 +0200
committerAraq <rumpf_a@web.de>2018-10-02 16:18:16 +0200
commitae901b327246f66c4082d09fedbc35ee6a42421b (patch)
treec012b7fec0263851dd2e8e71bf46a3b90fde0110 /doc/docgen_sample.nim
parentf98352a49800b5b8536af49af3bcee0ca6b54a44 (diff)
downloadNim-ae901b327246f66c4082d09fedbc35ee6a42421b.tar.gz
fixes #7351
Diffstat (limited to 'doc/docgen_sample.nim')
0 files changed, 0 insertions, 0 deletions
103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247
#
#
#            Nim's Runtime Library
#        (c) Copyright 2014 Nim Contributors
#
#    See the file "copying.txt", included in this
#    distribution, for details about the copyright.
#

## :Authors: Zahary Karadjov, Andreas Rumpf
##
## This module provides support for `memory mapped files`:idx:
## (Posix's `mmap`:idx:) on the different operating systems.

when defined(windows):
  import winlean
elif defined(posix):
  import posix
else:
  {.error: "the memfiles module is not supported on your operating system!".}

import os

type
  MemFile* = object  ## represents a memory mapped file
    mem*: pointer    ## a pointer to the memory mapped file. The pointer
                     ## can be used directly to change the contents of the
                     ## file, if it was opened with write access.
    size*: int       ## size of the memory mapped file

    when defined(windows):
      fHandle: int
      mapHandle: int 
    else:
      handle: cint

{.deprecated: [TMemFile: MemFile].}

proc mapMem*(m: var MemFile, mode: FileMode = fmRead,
             mappedSize = -1, offset = 0): pointer =
  var readonly = mode == fmRead
  when defined(windows):
    result = mapViewOfFileEx(
      m.mapHandle,
      if readonly: FILE_MAP_READ else: FILE_MAP_WRITE,
      int32(offset shr 32),
      int32(offset and 0xffffffff),
      if mappedSize == -1: 0 else: mappedSize,
      nil)
    if result == nil:
      raiseOSError(osLastError())
  else:
    assert mappedSize > 0
    result = mmap(
      nil,
      mappedSize,
      if readonly: PROT_READ else: PROT_READ or PROT_WRITE,
      if readonly: (MAP_PRIVATE or MAP_POPULATE) else: (MAP_SHARED or MAP_POPULATE),
      m.handle, offset)
    if result == cast[pointer](MAP_FAILED):
      raiseOSError(osLastError())


proc unmapMem*(f: var MemFile, p: pointer, size: int) =
  ## unmaps the memory region ``(p, <p+size)`` of the mapped file `f`.
  ## All changes are written back to the file system, if `f` was opened
  ## with write access. ``size`` must be of exactly the size that was requested
  ## via ``mapMem``.
  when defined(windows):
    if unmapViewOfFile(p) == 0: raiseOSError(osLastError())
  else:
    if munmap(p, size) != 0: raiseOSError(osLastError())


proc open*(filename: string, mode: FileMode = fmRead,
           mappedSize = -1, offset = 0, newFileSize = -1): MemFile =
  ## opens a memory mapped file. If this fails, ``EOS`` is raised.
  ## `newFileSize` can only be set if the file does not exist and is opened
  ## with write access (e.g., with fmReadWrite). `mappedSize` and `offset`
  ## can be used to map only a slice of the file. Example:
  ##
  ## .. code-block:: nim
  ##   var
  ##     mm, mm_full, mm_half: MemFile
  ##
  ##   mm = memfiles.open("/tmp/test.mmap", mode = fmWrite, newFileSize = 1024)    # Create a new file
  ##   mm.close()
  ##
  ##   # Read the whole file, would fail if newFileSize was set
  ##   mm_full = memfiles.open("/tmp/test.mmap", mode = fmReadWrite, mappedSize = -1)
  ##
  ##   # Read the first 512 bytes
  ##   mm_half = memfiles.open("/tmp/test.mmap", mode = fmReadWrite, mappedSize = 512)

  # The file can be resized only when write mode is used:
  assert newFileSize == -1 or mode != fmRead
  var readonly = mode == fmRead

  template rollback =
    result.mem = nil
    result.size = 0

  when defined(windows):
    template fail(errCode: OSErrorCode, msg: expr) =
      rollback()
      if result.fHandle != 0: discard closeHandle(result.fHandle)
      if result.mapHandle != 0: discard closeHandle(result.mapHandle)
      raiseOSError(errCode)
      # return false
      #raise newException(EIO, msg)

    template callCreateFile(winApiProc, filename: expr): expr =
      winApiProc(
        filename,
        if readonly: GENERIC_READ else: GENERIC_ALL,
        FILE_SHARE_READ,
        nil,
        if newFileSize != -1: CREATE_ALWAYS else: OPEN_EXISTING,
        if readonly: FILE_ATTRIBUTE_READONLY else: FILE_ATTRIBUTE_TEMPORARY,
        0)

    when useWinUnicode:
      result.fHandle = callCreateFile(createFileW, newWideCString(filename))
    else:
      result.fHandle = callCreateFile(createFileA, filename)

    if result.fHandle == INVALID_HANDLE_VALUE:
      fail(osLastError(), "error opening file")

    if newFileSize != -1:
      var 
        sizeHigh = int32(newFileSize shr 32)
        sizeLow  = int32(newFileSize and 0xffffffff)

      var status = setFilePointer(result.fHandle, sizeLow, addr(sizeHigh),
                                  FILE_BEGIN)
      let lastErr = osLastError()
      if (status == INVALID_SET_FILE_POINTER and lastErr.int32 != NO_ERROR) or
         (setEndOfFile(result.fHandle) == 0):
        fail(lastErr, "error setting file size")

    # since the strings are always 'nil', we simply always call
    # CreateFileMappingW which should be slightly faster anyway:
    result.mapHandle = createFileMappingW(
      result.fHandle, nil,
      if readonly: PAGE_READONLY else: PAGE_READWRITE,
      0, 0, nil)

    if result.mapHandle == 0:
      fail(osLastError(), "error creating mapping")

    result.mem = mapViewOfFileEx(
      result.mapHandle,
      if readonly: FILE_MAP_READ else: FILE_MAP_WRITE,
      int32(offset shr 32),
      int32(offset and 0xffffffff),
      if mappedSize == -1: 0 else: mappedSize,
      nil)

    if result.mem == nil:
      fail(osLastError(), "error mapping view")

    var hi, low: int32
    low = getFileSize(result.fHandle, addr(hi))
    if low == INVALID_FILE_SIZE:
      fail(osLastError(), "error getting file size")
    else:
      var fileSize = (int64(hi) shr 32) or low
      if mappedSize != -1: result.size = min(fileSize, mappedSize).int
      else: result.size = fileSize.int

  else:
    template fail(errCode: OSErrorCode, msg: expr) =
      rollback()
      if result.handle != 0: discard close(result.handle)
      raiseOSError(errCode)
  
    var flags = if readonly: O_RDONLY else: O_RDWR

    if newFileSize != -1:
      flags = flags or O_CREAT or O_TRUNC
      var permissions_mode = S_IRUSR or S_IWUSR
      result.handle = open(filename, flags, permissions_mode)
    else:
      result.handle = open(filename, flags)

    if result.handle == -1:
      # XXX: errno is supposed to be set here
      # Is there an exception that wraps it?
      fail(osLastError(), "error opening file")

    if newFileSize != -1:
      if ftruncate(result.handle, newFileSize) == -1:
        fail(osLastError(), "error setting file size")

    if mappedSize != -1:
      result.size = mappedSize
    else:
      var stat: TStat
      if fstat(result.handle, stat) != -1:
        # XXX: Hmm, this could be unsafe
        # Why is mmap taking int anyway?
        result.size = int(stat.st_size)
      else:
        fail(osLastError(), "error getting file size")

    result.mem = mmap(
      nil,
      result.size,
      if readonly: PROT_READ else: PROT_READ or PROT_WRITE,
      if readonly: (MAP_PRIVATE or MAP_POPULATE) else: (MAP_SHARED or MAP_POPULATE),
      result.handle,
      offset)

    if result.mem == cast[pointer](MAP_FAILED):
      fail(osLastError(), "file mapping failed")

proc close*(f: var MemFile) =
  ## closes the memory mapped file `f`. All changes are written back to the
  ## file system, if `f` was opened with write access.
  
  var error = false
  var lastErr: OSErrorCode

  when defined(windows):
    if f.fHandle != INVALID_HANDLE_VALUE:
      error = unmapViewOfFile(f.mem) == 0
      lastErr = osLastError()
      error = (closeHandle(f.mapHandle) == 0) or error
      error = (closeHandle(f.fHandle) == 0) or error
  else:
    if f.handle != 0:
      error = munmap(f.mem, f.size) != 0
      lastErr = osLastError()
      error = (close(f.handle) != 0) or error

  f.size = 0
  f.mem = nil

  when defined(windows):
    f.fHandle = 0
    f.mapHandle = 0
  else:
    f.handle = 0
  
  if error: raiseOSError(lastErr)