git-gui: check browser/blame arguments carefully
git gui offers two related commands, browser and blame, that provide graphical interfaces driven by git ls-tree and git blame. As such, the arguments to git-gui need to satisfy those two git commands. But, git-gui does not assure this leading to confusing or incorrect results. For instance 'git browser <non-existent path>' shows a blank browser window rather than error message. Also, commit 3e45ee1ef2 ("git-gui: Smarter command line parsing for browser, blame", 2007-05-08) implemented code to allow giving path before rev on the command line, and unconditionally uses the worktree to disambiguate. As a result, the following command run in a current git-gui checkout of the master branch shows the master branch version of blame.tcl, when none should be shown as that file does not exist in gitgui-0.6.0. git gui blame lib/blame.tcl gitgui-0.6.0 This 'file before rev' feature in git-gui mirrors ideas considered when git's user interface was very young, but no such feature is documented for any git command. Rather than try to fix an idea git itself rejected, let's just remove this broken and hopefully unused feature. git-gui browser|blame both accept 'rev' and 'path' as command line arguments. rev defaults to 'HEAD' if not given, while path must be given. path names a directory tree to ls-tree or a file to blame. path must exist in rev for ls-tree and for blame. In addition git blame will include uncommitted changes from the worktree file at 'path' if rev is not given (thus defaulting to HEAD), but still requires that the file exists in HEAD. So, let's clean up the parser to check that the arguments are usable. - give a full synopsis, including '--' that may be used to separate rev and path. (as path is the required final arg, -- gives no extra info) - explicitly check the number of arguments - use rev-parse to assure a user supplied rev is valid - use ls-tree to assure that path exists in rev - for blame only, with no rev given and a worktree existing, also assure that path points to a file in the worktree With these changes, error messages are thrown by the parser if the path or rev are not known: no blank or erroneous displays are created. Also, this avoids accessing the worktree except in the specific use case supported by blame / git-blame, meaning browser|blame now also work without a worktree. Signed-off-by: Mark Levedahl <mlevedahl@gmail.com> Signed-off-by: Johannes Sixt <j6t@kdbg.org>