I have created a browser extension that allows to navigate through local images using arrow keys. To do that, it fetches the directory index and adds images, which are next to the currently opened one, to the DOM. E.g. when you open file:///path/to/image.png in Firefox, the content script of the add…

There may be a way… Cannot open local file from dial opened 08:19PM - 01 Mar 21 UTC (UTC) closed 10:10PM - 29 Jan 22 UTC (UTC) [image] maharvey …

Thanks for pointing this out. I already found this issue comment some time ago. Unfortunately, it’s for another use case where you want to have a link to a local file on a web page. This workaround enables file:/// links which are otherwise not clickable. But it would be great to have a similar way …

[image] nikolockenvitz: I also tried adding "file:///*" to permissions in manifest - also didn’t work. I don’t know if Firefox supports the filesystem: scheme in extension CSPs, or if that would even help in this case, but I can’t think of anything else :frowning: [image] content_se…

Thanks. But this does not work for my use case. While Firefox recognizes the filesystem: scheme, it still does not allow to fetch anything from the local files. In my understanding, CSP is just an additional security measure: If you cannot load a resource because it’s a blocked Cross-Origin Request,…

https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Working_with_files outlines all file system interactions that should work.

Thanks @freaktechnik and @hans_squared ! It seems it’s not possible at the moment. In the meantime I had another idea how to enable file access without disabling the security measure completely. One could create an extension that intercepts all file:// requests and blocks them unless they are from a…

How to access local files from an extension?

Add-ons Development

hans_squared (Hans Squared) February 9, 2022, 12:52pm 7

I just saw that Firefox supports https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/extension/isAllowedFileSchemeAccess

But actually allowing file:// scheme access hasn’t been implemented:

Topic		Replies	Views
Opening links to local files file:// Development	9	34949	August 2, 2021
Requesting `file:///*` permission dynamically via `browser.permissions.request()` Development webextensions-api , permissions	1	99	June 24, 2026
Securely incorporating local resources into an extension page Development	3	620	November 28, 2020
Is there a browser preference that will permit extensions to fetch from local disk? Development	4	1323	August 31, 2020
Load local files (images and or CSS) in SDK add-on Development	10	3862	February 17, 2016

How to access local files from an extension?

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