Today its only possible to update webmin at once if a new release is provideded or update complete modules or themes from a WBM file. What's missimg is the posibility to provide patches to modules or themes...

PR #875 for a small but important typo leads me to think (again) about a patch functionality for webmin, see discussion webmin/authentic-theme#1069 with @qooob abbout this topic.

The solution seems to be straigthforward: Implement possibility for incremental updates from WMB files!
This is whats be done by this PR.

Whats in this PR:

• do not delete old module or theme if patch.info is provided
• WBM file contains only changed files and patch.info

very simply and IMHO straigthforward ...

What is this useful for:

• preparing a new release for a small fix is much work, so it's for small fixes that are important for some people but not worth a full release
• can be used from community to fix for external modules no more maintained, e.g. Commodo WAF Comodo WAF module authentic-theme#1054
  no more need for manual editing module files to make it work.
• individualisation, e.g. a company want's to have other icons or strings inculding the company name
• simple to use for not experienced end users like installing an additional module or theme
• ... (anything else including Webmin hotfixes or scripting by using postinstall.pl)

Why not simply update from repo?

• dev repo may be broken or have new, but not fully tested functionallty
• update from repo cannot fix external modules or provide induvidualisation
• even if @qooob plans to provide an UI, there is a risc for not experiend end users to break things

Content of patch.info:

• can contain every value allowed for module.info or theme.info, these are processed the same way as of now. e.g. requiring a minimum version of webmin or module or a special perl module:

name=Hotfix for spam
desc=Hotfix for spam
depends=spam/1.881
os_support=!windows

Test it:

• got to webmin install modules as you would do to install a regular module
• enter URL https://dealz.rrr.de/webmin/hotfix-spam-1881.tar.gz and hit "Install module"to fix issue from PR PR Update save_report.cgi #875

spam/save_report.cgi before

    if (!in{"spam_level_char_def"} && &char_check($in{"spam_level_char"})) {
        push(@adds, "all Level _STARS(".$in{ "spam_level_char"} .")_" );
        }

spam/save_report.cgi after

    if (!$in{"spam_level_char_def"} && &char_check($in{"spam_level_char"})) {
        push(@adds, "all Level _STARS(".$in{ "spam_level_char"} .")_" );
        }

• exchange grey-theme logos with others, e.g. company provided logo's:
  https://dealz.rrr.de/webmin/company-logos-gray-theme.tar.gz

Original:

After (Stressfree Icons):