File Types

Synopsis

• text files,

• compressed binary files,

• native apple files on the Macintosh,

• Mac resource forks, and

• symbolic links.

When a file is opened for add, Perforce attempts to determine the type of the file automatically. If the file is a regular file or a symbolic link, its type is set accordingly. Perforce then examines the first 1024 bytes of the file to determine whether it is text or binary. If any non-text characters are found, the file is assumed to be binary; otherwise, the file is assumed to be text.

Perforce administrators can use the type mapping feature (p4 typemap) to override Perforce's default file type detection mechanism. This feature is useful for binary file formats (such as Adobe PDF, or Rich Text Format) where files can start with 1024 or more characters of ASCII text, and might otherwise be mistaken for text files.

The base Perforce file types are:

The file type modifiers are:

A file's type is normally preserved between revisions, but can be overridden or changed with the -t flag during add, edit, or reopen operations:

• p4 add -t filetype filespec adds the files as the specified type.

• p4 edit -t filetype filespec opens the file for edit as the specified type. The file's type is changed to the specified filetype only after it is submitted to the depot.

• p4 reopen -t filetype filespec changes the type of a file already open for add or edit.

Keyword Expansion

Usage Notes

• The type of an existing file can be determined with p4 opened or p4 files.

• Delta storage (the default mode with text files) is a method whereby only the differences (or deltas) between revisions of files are stored. Full file storage (the default mode with binary files) involves the storage of the entire file. The file's type determines whether full file or delta storage is used. Perforce uses RCS format for delta storage.

• Some of the file types are compressed to gzip format for storage in the depot. The compression occurs during the submission process, and decompression happens while syncing. The process is transparent to the user; the client workspace always contains the file as it was submitted.

• Symbolic links on non-UNIX clients appear as small text files containing a relative path to the linked file. Editing these files on a non-UNIX client should be done with caution, as submitting them to the depot may result in a symbolic link pointing to a nonexistent file on the UNIX client.

• Some file type changes do not affect earlier revisions stored in the depot. For instance, changing a file's type by adding the +S (temporary object) modifier tells Perforce to store only the head revision of the file in the depot. If you do this to a previously-existing file, any subsequent changes to the file will overwrite the one stored at the head revision, but revisions to the file stored in the depot before the +S modifier was used will remain unaffected.

• The modtime (+m) modifier is a special case: It is intended for use by developers who need to preserve a file's original timestamp. (Normally, Perforce updates the timestamp when a file is synced.) It allows a user to ensure that the timestamp of a file in a client workspace after a p4 sync will be the original timestamp existing on the file at the time of submission (that is, not the time at the Perforce server at time of submission, and not the time on the client at the time of sync).

The most common case where this is useful is development involving the third-party DLLs often encountered in Windows environments. Because the timestamps on such files are often used as proxies for versioning information (both within the development environment and also by the operating system), it is sometimes necessary to preserve the files' original timestamps regardless of a Perforce user's client settings.

The +m modifier on a file allows this to happen; if set, Perforce will ignore the modtime ("file's timestamp at time of submission") or nomodtime ("date and time on the client at time of sync") option setting of the client workspace when syncing the file, and always restore the file's original timestamp at the time of submit.

• Versions of Perforce prior to 99.1 used a set of keywords to specify file types. These keywords are still supported, but have been made redundant. The following table lists the old keywords alongside their current base file types and modifiers:

  Old Keyword	Description	Base Filetype	Modifiers
  text	Text file	text	none
  xtext	Executable text file	text	+x
  ktext	Text file with RCS keyword expansion	text	+k
  kxtext	Executable text file with RCS keyword expansion	text	+kx
  binary	Non-text file	binary	none
  xbinary	Executable binary file	binary	+x
  ctext	Compressed text file	text	+C
  cxtext	Compressed executable text file	text	+Cx
  symlink	Symbolic link	symlink	none
  resource	Macintosh resource fork	resource	none
  ltext	Long text file	text	+F
  xltext	Executable long text file	text	+Fx
  ubinary	Uncompressed binary file	binary	+F
  tempobj	Temporary object	binary	+S
  tempxobj	Temporary executable object	binary	+Sx