fix(deep-link): remove quotes from Exec path in .desktop file on Linux (fix tauri-apps/tauri#10570)

[0xPxt]

The register() function wraps the Exec path in literal double quotes when generating .desktop files on Linux:

let qualified_exec = format!("\"{}\" %u", exec);
// produces: Exec="/usr/bin/kunobi" %u

Per the freedesktop Desktop Entry Spec, Exec values are not shell-parsed — the quotes become part of the binary path. When xdg-open handles a deep link URL, it extracts the first token (including the literal " characters) and fails to find it:

$ XDG_UTILS_DEBUG_LEVEL=2 xdg-open "myapp://callback"
/usr/bin/xdg-open: 811: : Permission denied

Removing the quotes fixes deep link delivery on Linux.

Intended to resolve tauri-apps/tauri#10570

[FabianLars]

Intended to resolve tauri-apps/tauri#10570

I doubt it helps. The quotes were added a month ago. This issue is 2 years old.

Now you're not the first one (unless you were the one on discord) to report having issues with the quotes but they were added because we had issues with paths with spaces.
desktop-file-validate also does not complain about the quotes.
The linked spec also says the following

Arguments may be quoted in whole. If an argument contains a reserved character the argument must be quoted. The rules for quoting of arguments is also applicable to the executable name or path of the executable program as provided.

Looks like this is a bug in xdg-open https://gitlab.freedesktop.org/xdg/xdg-utils/-/work_items/151 - we should double check that spaces are broken (i'll try to get the repro that prompted us to add the quotes) and then maybe set the quotes only if we detect quotes.