Can I make Firefox display a file of known type (from a Subversion repository) as text?

Question

When browsing a Subversion repository using Firefox and the http(s): URL, I want to take a quick look at text files in the browser itself. However, while Firefox displays unknown file types as text, when I click on a C header it only offers to save it or open it with MSVS (Visual Studio), not to display it.

Requirements

• One should be able to open a link as text in the browser in the same or a new tab or window.
  • Preferably also to retain the option to save or open in an application
• One should preferably be able to do so just using mouse clicks.
• While the problem may be related to the Subversion server, a solution for arbitrary sites is clearly preferable.
• A nice extra would be if one could configure the behaviour differently per site or page.

Constraints

• It is unlikely that I can get any settings changed in the Subversion server. (I can commit file and attribute modifications normally.)

Ideas and attempts

I suspect that the current behaviour is because .h is a known file type, but it used to behave differently even though MSVS was installed; the server may however have been older.

I hoped choosing “Open with Notepad” + “Do this automatically” would make it appear in the Options/Applications, letting me change it, but at first that did not work at all, until I thought of refreshing the options page! But even then, I only get the choice of downloading or opening with an application, while I want to open it as text in a Firefox tab.

Manually prefixing view-source: to the URL of the repository element works.

It occurs to me that defining an “application” that opens the URL prefixed by view-source: in Firefox (in a new tab or the same) might work.

(2017-01-13) Using Firefox Network Monitor I see that the file is served with mime-type text/x-c. The related information in mimeTypes.rdf is:

 <RDF:li RDF:resource="urn:mimetype:text/x-c"/>
 …
 <RDF:Description RDF:about="urn:mimetype:externalApplication:text/x-c"
                  NC:prettyName="notepad.exe"
                  NC:path="C:\Windows\System32\notepad.exe" />
 …
 <RDF:Description RDF:about="urn:mimetype:handler:text/x-c"
                  NC:alwaysAsk="true">
   <NC:externalApplication RDF:resource="urn:mimetype:externalApplication:text/x-c"/>
   <NC:possibleApplication RDF:resource="urn:handler:local:C:\Windows\System32\notepad.exe"/>
 </RDF:Description>
 …
 <RDF:Description RDF:about="urn:mimetype:text/x-c"
                  NC:value="text/x-c"
                  NC:editable="true"
                  NC:fileExtensions="h"
                  NC:description="C/C++ Header">
   <NC:handlerProp RDF:resource="urn:mimetype:handler:text/x-c"/>
 </RDF:Description>

Following Ben’s answer, setting the Subversion property svn:mime-type ↦ text/plain solves the problem – it is then served as such, but if that is not wanted, one may want to use the Mozilla documentation of mimeTypes.rdf to modify the treatment of text/x-c – but it is not clear to me how.

Related questions

• How to have Firefox save txt files automatically instead of opening in browser — This is the other way round: they want to prevent opening it in the browser; I want to force or offer that.
• Firefox — How to open a link (to any text-based file) in Vim? – This is about getting a desired application into the list. It mentions the interesting extension Open with, but that doesn’t really help.
• How can I make Google Chrome display a plain text HTTP response, rather than downloading it in a file? — This applies to Google Chrome and does not seem to offer a solution. It may however explain the change in behaviour: use of Content-disposition: attachment in the header? The trick of prefixing view-source: to the URL does work (for .h), but requires manual intervention.
• Make Chrome always open PDFs itself — This applies to Google Chrome but is somewhat similar; it also mentions a Chrome extension Redirector to remove Content-disposition: attachment, but I see no documentation there.
• How can I make Firefox annotate links which point to files such as PDFs, which won't be opened in Firefox? — Sounds powerful enough to do the job, but involves some programming and a learning curve, unless a script is available.

Notes

• _{Tagged with [svn] as it may depend on how the links are served.}
• _{Tagged with [windows] as it may depend on the known file types defined in MS Windows.}
• _{The Subversion server is a TeamForge/CollabNet^{© 2014} ¿unable to get version by any of the methods in SO / how-to-find-my-subversion-server-version-number?.}

Answer 1

Often SVN servers will automatically use a text context type when serving up .c/.h files, so I'm surprised this isn't already happening for you.

You can try setting the svn:mime-type property on these files to "text/plain", or verifying that a different mime type is not already set on those files. SVN servers use this property to determine the http content type in the response to a GET query. Experiment with one or two files before applying it globally, however!

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http://svnbook.red-bean.com/en/1.8/svn.advanced.props.file-portability.html#svn.advanced.props.special.mime-type