Open Bug 123320 Opened 23 years ago Updated 2 years ago

.chm (Compiled HTML) Support


(Firefox :: File Handling, enhancement)





(Reporter: aros, Unassigned)



(Keywords: helpwanted, parity-ie)


(1 file)

From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.8+) Gecko/20020202

I want very much the mozilla to support micro$oft's .chm format (that stands for
compiled HTML)

Reproducible: Always
Steps to Reproduce:
1. Try to open any chm file
2. you'll get nothing :)

Actual Results:  no support

Expected Results:  Support
What this should be:
Summary => "[RFE] .chm (Compiled HTML) Support"

I'm not sure if we really should implement this.
Summary: This is not a bug but required feature → [RFE] .chm (Compiled HTML) Support
Since .chm is a Microsoft proprietary data format, I see no reason
for Mozilla supporting it.
Artem, is there a clear specification available that explains the .chm format?
I know this is filed, but I can't find it :-(.

chm is bascically a cab, which is like a zip.
Assignee: trudelle → dougt
Component: XP Apps → Networking: File
QA Contact: sairuh → benc
Summary: [RFE] .chm (Compiled HTML) Support → .chm (Compiled HTML) Support
Whiteboard: DUPEME
not related to file: protocol
Assignee: dougt → law
Component: Networking: File → File Handling
QA Contact: benc → sairuh
dougt: to support chm we will need the same sort of code as for jar. which afaik lives in necko. Otoh, the reason i sent it to Netwerk was because i hoped the QA could dupe it for me.
->future/helpwanted, cc ben
Keywords: helpwanted
Target Milestone: --- → Future
Those documents all nicely describe how one generates chm files using various
(mostly microsoft) tools.  The documents say nothing about:

1)  Reading a chm file in anything but the help viewer
2)  The actual format of the chm files

So as things stand the way to support chm would be to reverse-engineer the
format by trial and error... 
No dupes found. Confirming enhancement request.
Ever confirmed: true
Whiteboard: DUPEME
This Bug is Platform All, OS All; does that mean the request is to implement
.chm Support on all platforms? Like we did with Windows BMP and ICO (I think)?
.chm support is worth implementing at least on non Windows platforms
This would mean that I could create a set of documents or a book, pack it into a
.chm and give it to somebody(?).
Also, I guess it would be possible to pack multiple HTML pages on a website into
a single .chm file.
A parital description of the format is available at wotsit:
QA Contact: sairuh → petersen
Comment on attachment 129274 [details]
This is an LGPL library which provides a full support for CHM

Just a reminder, you can't commit LGPL code into mozilla. Code must be
Attachment #129274 - Attachment description: This is a library which provides a full support for CHM → This is an LGPL library which provides a full support for CHM
A dissassembly of .CHM format can be found here:

One can easily create a parser of .CHM using this draft ;)
Blocks: 82118
Whiteboard: parity-ie
This is an e-mail response I've got from CHMlib developer. He agree to relicense
his library to whatever license you need. Please, give me a point what to ask
him if this bug is still relevant. (His e-mail is

On Thu, Aug 04, 2005 at 11:22:51PM +0600, Artem S. Tashkinov wrote:

>> Hi there!
>> Mozilla developers in order to implement CHM files support require your 
>> library to be trilicensed. Please, visit 
>> for details.

I'm not opposed to "trilicensing" chmlib, I think, though I don't exactly know
what this means.  It's got to be made available under three different
licenses?  Or...  Can you point me at some information on what trilicensing
means in this context?

- jed explains how the
trilicense stuff works.

Past that, would need to be talked to about adding another
library into the mozilla tree, I guess.  And then someone would have to actually
do the work of making this library interact with Gecko in the right way.
Assignee: law → nobody
I own a software company which creates .html files with links to a chm file. An example of such a link is:

<A HREF = "mk:@MSITStore:C:\Program Files\RUG Tools\RUG-III Analyzer 1.31\Includes\MDS20Item.chm::/g1aactivitiesofdailylivingadlselfperformance7daylookback1.htm" target="_blank">G1aA</A>

I got this URL by using Micorosoft's HTML Help viewer program, right clicking on links, and seeing the properties.

Internet Explorer handles this fine, but Mozilla Firefox gives me the error message:

Firefox doesn't know how to open this address, because the protocol (mk) isn't associated with any program.

I am a novice user of Firefox, and I realize this bulletin board is for developers. But if you could tell me how I can get Firefox to associate a program with this protocol, and which program to use, or any other workaround for my clients, please let me know.

QA Contact: chrispetersen → file-handling
Product: Core → Firefox
Target Milestone: Future → ---
Version: Trunk → unspecified
Mass bug change to replace various 'parity' whiteboard flags with the new canonical keywords. (See bug 1443764 comment 13.)
Keywords: parity-ie
Whiteboard: parity-ie
Severity: normal → S3
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