Perforce File Type Options

Automatic type detection and file type usage recommendations

PROBLEM

What Perforce filetypes should I use?

SOLUTION

Automatic File Type Detection

The Perforce Server identifies binary and text files based on whether it detects non-text characters in the first 8192 bytes of the file. Revisions of binary files are stored intact, but text files are diffed with the previous revision and only the changes (the "deltas") are stored.

Overriding Automatic File Type Detection

To override the Perforce file type detection logic when required, you can map operating system file types to Perforce file types using the Perforce typemap feature. For example, Postscript files are textual in format, but because (1) diffs between revisions are not useful and (2) diffing huge Postscript files can adversely affect server performance, you can use typemap to specify that Postscript files be stored as type binary, which are not diffed by default.

Basic File Typing Guidelines

Some basic guidelines for assigning file types:

• If the file is textual and can be meaningfully diffed, store it as text.
  Example: README files.
   
• If the file is textual but cannot be meaningfully diffed, choose binary or text+C. 
  Example: Large application-generated text files, Postscript files.

Recommendations

Acrobat (PDF) files

If you store PDF files in your depot, map them to the binary file type. PDF files have a textual header that can cause old (pre-2000.1) Perforce clients to identify them as text files.

Avoiding Accidental File Truncation

Some operating systems (notably Windows), interpret the Control-Z character (decimal 26 or hex 0x1a) as the end of file. To prevent inadvertent truncation, never store binary file content as text.

Very Large Text Files

Some programs generate very large text files. For example, certain chip design files can have file sizes up to 100MB. In general, storing text files over 2MB in RCS format is inefficient. Such large text files should generally be stored as compressed text (text+C) to avoid the overhead of computing deltas when editing files or accessing old revisions.

Common File Types

The following table lists some recommended Perforce file types and attributes for common file types.

Extension	Perforce file type	Description
.asp	text	Active server page file
.avi	binary+F	Video for Windows file
.bmp	binary	Windows bitmap file
.btr	binary	Btrieve database file
.cnf	text	Conference link file
.css	text	Cascading style sheet file
.doc	binary	Microsoft Word document
.dot	binary	Microsoft Word template
.exp	binary+w	Export file (Microsoft Visual C++)
.gif	binary+F	GIF graphic file
.htm	text	HTML file
.html	text	HTML file
.ico	binary	Icon file
.inc	text	Active Server include file
.ini	text+w	Initial application settings file
.jpg	binary	JPEG graphic file
.js	text	JavaScript language source code file
.lib	binary+w	Library file (several programming languages)
.log	text+w	Log file
.mpg	binary+F	MPEG video file
.pdf	binary	Adobe PDF file
.pdm	text+w	Sybase Power Designer file
.ppt	binary	Microsoft Powerpoint file
.xls	binary+w	Microsoft Excel file
.zip	binary+F	Compressed archive file

Additional Resources

For more information about Perforce file types, including handling of Unicode files, please refer to Appendix B of the P4 User's Guide.

For more information about using p4 typemap, refer to the Perforce Command Reference and the Perforce System Administrator's Guide.