LHA/LHarc self-extracting archive
LHA/LHarc self-extracting archive refers to the various self-extracting archive formats associated with the LHarc/LHA family of compressed archive utilities.
Refer to LHA for information about the underlying archive format.
This article primarily covers files for the DOS platform. (TODO: Other platforms.)
Note that some relatives of LHA, such as LArc and PMA, have self-extracting archive formats that are not covered here.
Discussion
The usual manner of creating a self-extracting archive is to first create a normal (.LZH/.LHA) archive, then run the software on that non-executable archive using the "s" function.
LHarc v1.x can create archives in either COM or EXE format. LHA v2.x only supports EXE format.
Starting with v1.12, EXE files can be structured in two different ways: "Small model" (the default), or "Large model". Large model is selected by using the /x (v1.x) or /x1 (v2.x) option.
Identification
LHarc/LHA self-extracting archives contain a text message that will be printed when the files are extracted, which could be useful for format identification. Unfortunately, the message is not consistently located or formatted.
An example of such a message is "LHarc's SFX 1.13S (c) Yoshi, 1989". It contains a version number (which may only be approximate), and usually an "S" or "L" suffix indicating Small or Large model.
The following table summarizes most of the DOS formats.
| Exec. format | Versions | Model | Offset | Message begins... |
|---|---|---|---|---|
| DOS COM | 1.00 | 6 | "SFX of LHarc"
| |
| DOS COM | 1.12-1.13 | 6 | "LHarc's SFX"
| |
| DOS COM | 1.14β | 6 | "LHARC SFX"
| |
| DOS EXE | 1.00 | 38 | "SFX of LHarc"
| |
| DOS EXE | 1.12-1.13 | S | 38 | "LHarc's SFX"
|
| DOS EXE | 1.14β | S | 38 | "LHARC SFX"
|
| DOS EXE | 1.12-1.13 | L | 37 | "LHarc's SFX"
|
| DOS EXE | 1.14β | L | 37 | "LHARC SFX"
|
| DOS EXE | 2.05 | S or L | 36 | "LH's SFX"
|
| DOS EXE | 2.06-2.10 | S or L | 36 | "LHa's SFX"
|
| DOS EXE | 2.11-2.66 | S or L | 36 | "LHA's SFX"
|
Additionally, DOS COM files start with byte 0xeb.
Software
Refer to LHA#Software, especially the main LHarc/LHA software.
