Rewrite into more POSIX-compliant, portable, robust, composable and readable shell scripts

[9ao9ai9ar]

Closes #1855 and fixes #1810.

The rewrite is mostly complete, but there are still some parts left to fix, mainly in prefsCleaner.sh. Although currently I have marked the pull request as draft, I consider it structurally stable enough for review. Once I have merged the changes in 9ao9ai9ar:posix-sh-bugfix, I will mark this pull request as ready for review, or ready to be merged. Unfortunately, I can not tell when that will be, as I:

1. no longer have as much free time as before;
2. need time to study Firefox's source code and documentation and do some experimentation on my own to ensure the critical parts of the new code are correct and optimal;
3. need time to test and tick off the items in the test matrix below, which I came up with based on the supported build hosts and targets of Firefox;
4. need time to think about the different approaches to update and prune the user.js and prefs.js files, respectively, e.g. Linux auto updater (update when Firefox starts) #1696.

This is not the first POSIX solution to have ever been requested or presented, though certainly the most comprehensive one yet, so I hope this time the pull request really gets merged back to upstream and not closed off due to circumstances.

Target Platforms for Modern Desktop Versions of Firefox

Tier-1

• Windows
• macOS
• Fedora
• Debian
• Ubuntu

Tier-2

• openSUSE
• Arch Linux
• Alpine Linux
• NixOS

Tier-3

• FreeBSD
• OpenBSD
• NetBSD
• Solaris (11+)

Non-Tiered

• OpenIndiana
• Haiku (Iceweasel)

POSIX-Compatible Shells

• bash 3 (macOS)
• bash
• osh
• pdksh
• ksh93u+(m)
• mksh
• ash
• dash
• posh
• hush
• zsh (via emulate sh)
• yash
• mrsh
• gash
• pbosh

[MagicalDrizzle]

prefCleaner works fine for me, however updater doesn't seem to be able to append overrides.

[MagicalDrizzle]

Seems to be just a broken check? This fixes it and updater seems to work fine now.
if ! [ "$SKIPOVERRIDE" ]; > if [ "$SKIPOVERRIDE" = false ];

[MagicalDrizzle]

Error in both scripts - you were checking for the literal file named SCRIPT_FILE:

// from
SCRIPT_FILE=$(preadlink "$0") && [ -f SCRIPT_FILE ] || exit 1
// to
SCRIPT_FILE=$(preadlink "$0") && [ -f $SCRIPT_FILE ] || exit 1

and for your missing /bin/sh question - no it doesn't seem to work.

[jamesericdavidson]

@9ao9ai9ar Thoughts on using #!/usr/bin/env? sh could be busybox, the gimped version of Bash (which is not POSIX-compliant), etc.

[9ao9ai9ar]

@9ao9ai9ar Thoughts on using #!/usr/bin/env? sh could be busybox, the gimped version of Bash (which is not POSIX-compliant), etc.

The POSIX way to do it is to write a program to overwrite the shebang with the path of sh as determined by getconf PATH at install-time (see the relevant section in the POSIX document), but I think that is overkill and I would just ask the users to change it themselves if needed. My personal opinion is /bin/sh is better or at least no worse than /usr/bin/env sh because /usr might not be mounted, and the former allows specifying options to sh as an added bonus. I might reconsider the choice if /usr/bin/env sh somehow turns out to work better for the subset of operating systems the scripts are intended to support, but that doesn't seem likely now that I've verified modern Firefox is not available on Solaris 10.

[aartoni]

Hey @9ao9ai9ar @MagicalDrizzle I've noticed that progress on this PR is slowing down, so I'm willing to create a checklist of things to ensure that the script is working properly, and then make a GitHub workflow to test the script on different platforms.

Here are some things to be checked:

• normal execution returns EX_OK
• check every non-zero EX_*
• user.js gets updated
• user-overrides.js is respected

This will tick the GitHub available runners off the list of things that testers have to check manually. Manual tester can then copy the workflow to test locally.

What do you think? An alternative would be splitting this PR into smaller PRs.

[MagicalDrizzle]

@9ao9ai9ar prefsCleaner works, updater only partly - works only if there's already an user.js file. It won't download a new user.js if doesn't exist, then will try to backup the nonexistent user.js file which fails.

+ userjs_backup=/home/demo/Downloads/profile/userjs_backups/user.js.backup.2024-12-01_0511
+ mkdir -p /home/demo/Downloads/profile/userjs_backups
+ cp /home/demo/Downloads/profile/user.js /home/demo/Downloads/profile/userjs_backups/user.js.backup.2024-12-01_0511
cp: cannot stat '/home/demo/Downloads/profile/user.js': No such file or directory
+ userjs_backup=