Unicodeandcodepages

Unicode and codepage awareness

The many functions that deal with filenames in the sysutils routines have been changed from AnsiString to RawByteString so they do not perform implicit codepage conversions to the ANSI code page. At the same time, overloaded versions that accept a Unicode string have been created.

For routines that access actual OS functions using single-byte string APIS, the strings are converted to ensure that the OS routine receives a string with the correct encoding when using single-byte strings. This encoding is normally the DefaultFileSystemCodePage encoding.

On systems with a Unicode I/O API (2-byte strings), the native API is used, meaning that Unicode strings will be passed on as-is, but single-byte strings will be converted (implicitly) to Unicode.

The following is a minimal list of functions that have been changed and duplicated:

Name	Description
FileCreate	Create a new file and return a handle to it.
FileOpen	Open an existing file and return a file handle
FileExists	Check whether a particular file exists in the file system.
DirectoryExists	Check whether a directory exists in the file system.
FileSetDate	Set the date of a file.
FileGetAttr	Return attributes of a file.
FileSetAttr	Set the attributes of a file.
DeleteFile	Delete a file from the file system.
RenameFile	Rename a file.
FileSearch	Search for a file in a path.
ExeSearch	Search for an executable
FindFirst	Start a file search and return a findhandle
FindNext	Find the next entry in a findhandle.
FindClose	Close a find handle
FileIsReadOnly	Check whether a file is read-only.
GetCurrentDir	Return the current working directory of the application.
SetCurrentDir	Set the current directory of the application.

The following functions do not interact with the OS, but may nevertheless change the codepage of the strings involved in their operation:

Name	Description
ChangeFileExt	Change the extension of a filename.
ExtractFilePath	Extract the path from a filename.
ExtractFileDrive	Extract the drive part from a filename.
ExtractFileName	Extract the filename part from a full path filename.
ExtractFileExt	Return the extension from a filename.
ExtractFileDir	Extract the drive and directory part of a filename.
ExtractShortPathName	Returns a 8.3 path name
ExpandFileName	Expand a relative filename to an absolute filename.
ExpandFileNameCase	Expand a filename entered as case insensitive to the full path as stored on the disk.
ExtractRelativepath	Extract a relative path from a filename, given a base directory.
ExpandUNCFileName	Expand a relative filename to an absolute UNC filename.
IncludeTrailingPathDelimiter	Add trailing directory separator to a pathname, if needed.
IncludeTrailingBackslash	Add trailing directory separator to a pathname, if needed.
ExcludeTrailingBackslash	Strip trailing directory separator from a pathname, if needed.
ExcludeTrailingPathDelimiter	Strip trailing directory separator from a pathname, if needed.
IncludeLeadingPathDelimiter	Prepend a path delimiter if there is not already one.
ExcludeLeadingPathDelimiter	Strip the leading path delimiter of a path
IsPathDelimiter	Is the character at the given position a pathdelimiter ?
DoDirSeparators	Convert known directory separators to the current directory separator.
SetDirSeparators	Set the directory separators to the known directory separators.
GetDirs	Return a list of directory names from a path.
ConcatPaths	Concatenate an array of paths to form a single path
GetEnvironmentVariable	Return the value of an environment variable.