GetFileInfo

test.nim

import os, times

when defined(Windows):
  import winlean

  proc openHandle(path: string, followSymlink=true): THandle =
    var flags = FILE_FLAG_BACKUP_SEMANTICS or FILE_ATTRIBUTE_NORMAL
    if not followSymlink:
      flags = flags or FILE_FLAG_OPEN_REPARSE_POINT

  proc get_osfhandle*(fd:TFileHandle): THandle {.
    importc:"__get_osfhandle", header:"<io.h>".}

  type
    DeviceId = int32
    FileId = int64
else:
  import posix
  type
    DeviceId = TDev
    FileId = TIno

type
  FileInfo = object
    ## Contains information associated with a file object.
    id: tuple[device: DeviceId, file: FileId] # Device and file id.
    kind: TPathComponent # Kind of file object - directory, symlink, etc.
    size: BiggestInt # Size of file.
    permissions: set[TFilePermission] # File permissions
    linkCount: BiggestInt # Number of hard links the file object has.
    lastAccessTime: TTime # Time file was last accessed.
    lastWriteTime: TTime # Time file was last modified/written to.
    creationTime: TTime # Time file was created. Not supported on all systems!

template rawToFormalFileInfo(rawInfo, formalInfo): expr =
  ## Transforms the native file info structure into the one nimrod uses.
  ## 'rawInfo' is either a 'TBY_HANDLE_FILE_INFORMATION' structure on Windows,
  ## or a 'TStat' structure on posix
  when defined(Windows):
    template toTime(e): expr = winTimeToUnixTime(rdFileTime(e))
    template merge(a, b): expr = a or (b shl 32)
    formalInfo.id.device = rawInfo.dwVolumeSerialNumber
    formalInfo.id.file = merge(rawInfo.nFileIndexLow, rawInfo.nFileIndexHigh)
    formalInfo.size = merge(rawInfo.nFileSizeLow, rawInfo.nFileSizeHigh)
    formalInfo.linkCount = rawInfo.nNumberOfLinks
    formalInfo.lastAccessTime = toTime(rawInfo.ftLastAccessTime)
    formalInfo.lastWriteTime = toTime(rawInfo.ftLastWriteTime)
    formalInfo.creationTime = toTime(rawInfo.ftCreationTime)
    
    # Retrieve basic permissions
    if (rawInfo.dwFileAttributes and FILE_ATTRIBUTE_READONLY) != 0'i32:
      formalInfo.permissions = {fpUserExec, fpUserRead, fpGroupExec, 
                                fpGroupRead, fpOthersExec, fpOthersRead}
    else:
      result.permissions = {fpUserExec..fpOthersRead}

    # Retrieve basic file kind
    result.kind = pcFile
    if (rawInfo.dwFileAttributes and FILE_ATTRIBUTE_DIRECTORY) != 0'i32:
      formalInfo.kind = pcDir
    if (rawInfo.dwFileAttributes and FILE_ATTRIBUTE_REPARSE_POINT) != 0'i32:
      formalInfo.kind = succ(result.kind)

  else:
    template checkAndIncludeMode(rawMode, formalMode: expr) = 
      if (rawInfo.st_mode and rawMode) != 0'i32:
        formalInfo.permissions.incl(formalMode)
    formalInfo.id = (rawInfo.st_dev, rawInfo.st_ino)
    formalInfo.size = rawInfo.st_size
    formalInfo.linkCount = rawInfo.st_Nlink
    formalInfo.lastAccessTime = rawInfo.st_atime
    formalInfo.lastWriteTime = rawInfo.st_mtime
    formalInfo.creationTime = rawInfo.st_ctime

    result.permissions = {}
    checkAndIncludeMode(S_IRUSR, fpUserRead)
    checkAndIncludeMode(S_IWUSR, fpUserWrite)
    checkAndIncludeMode(S_IXUSR, fpUserExec)

    checkAndIncludeMode(S_IRGRP, fpGroupRead)
    checkAndIncludeMode(S_IWGRP, fpGroupWrite)
    checkAndIncludeMode(S_IXGRP, fpGroupExec)

    checkAndIncludeMode(S_IROTH, fpOthersRead)
    checkAndIncludeMode(S_IWOTH, fpOthersWrite)
    checkAndIncludeMode(S_IXOTH, fpOthersExec)

    formalInfo.kind = pcFile
    if S_ISDIR(rawInfo.st_mode): formalInfo.kind = pcDir
    if S_ISLNK(rawInfo.st_mode): formalInfo.kind.inc()

proc getFileInfo*(handle: TFileHandle, result: var FileInfo) =
  ## Retrieves file information for the file object represented by the given
  ## handle.
  ##
  ## If the information cannot be retrieved, such as when the file handle
  ## is invalid, an error will be thrown.
  # Done: ID, Kind, Size, Permissions, Link Count
  when defined(Windows):
    var rawInfo: TBY_HANDLE_FILE_INFORMATION
    # We have to use the super special '_get_osfhandle' call (wrapped above)
    # To transform the C file descripter to a native file handle.
    var realHandle = get_osfhandle(handle)
    if getFileInformationByHandle(realHandle, addr rawInfo) == 0:
      osError(osLastError())
    rawToFormalFileInfo(rawInfo, result)
  else:
    var rawInfo: TStat
    if fstat(handle, rawInfo) < 0'i32:
      osError(osLastError())
    rawToFormalFileInfo(rawInfo, result)

proc getFileInfo*(path: string, followSymlink = true): FileInfo =
  ## Retrieves file information for the file object pointed to by `path`.
  ## 
  ## Due to intrinsic differences between operating systems, the information
  ## contained by the returned `FileInfo` structure will be slightly different
  ## across platforms, and in some cases, incomplete or inaccurate.
  ## 
  ## When `followSymlink` is true, symlinks are followed and the information
  ## retrieved is information related to the symlink's target. Otherwise,
  ## information on the symlink itself is retrieved.
  ## 
  ## If the information cannot be retrieved, such as when the path doesn't
  ## exist, or when permission restrictions prevent the program from retrieving
  ## file information, an error will be thrown.
  when defined(Windows):
    var 
      handle = openHandle(path, followSymlink)
      rawInfo: TBY_HANDLE_FILE_INFORMATION
    if handle == INVALID_HANDLE_VALUE:
      osError(osLastError())
    if getFileInformationByHandle(handle, addr rawInfo) == 0:
      osError(osLastError())
    rawToFormalFileInfo(rawInfo, result)
    discard closeHandle(handle)
  else:
    var rawInfo: TStat
    if followSymlink:
      if lstat(path, rawInfo) < 0'i32:
        osError(osLastError())
    else:
      if stat(path, rawInfo) < 0'i32:
        osError(osLastError())
    rawToFormalFileInfo(rawInfo, result)

when isMainModule:
  echo(repr(getFileInfo(getAppFilename())))