FormulaInstaller now attempts to take a lock on a "foo.brewing" file for
the formula and all of its dependencies before attempting installation.
The lock is an advisory lock implemented using flock(), and as such it
only locks out other processes that attempt to take the lock. It also
means that it is never necessary to manually remove the lock file,
because the lock is not enforced by I/O.
The uninstall, link, and unlink commands all learn to respect this lock
as well, so that the installation cannot be corrupted by a concurrent
Homebrew process, and keg operations cannot occur simultaneously.
This has to be a last resort right? If all we show is that link (plus preceding un-deletable output) and they don't click it then maybe we should just close the ticket and hope they'll use MacPorts instead.
All logs are now stored from each command executed in Formula.install.
Error output is truncated to five lines in an attempt to not overwhelm the user and to encourage users to read the error output and report the bug properly. Maybe we can get that figure up from 70% to 90%.
If you google for "Cowardly refusing to sudo brew" you get a lot of confused users who didn't read any of the Homebrew documentation and then had a hissy-fit.
Rationale: it breaks stuff. You should not be able to install over something already installed *and* linked. brew now prompts you to unlink the existing linked keg first.
I came to fix this because I discovered that `brew install foo` works without --force provided foo's formula version is different to that which is installed and linked. I'm not sure if this was intentionally broken, but it led to at least two tickets I found where people were getting crazy issues trying to install over the top of already installed previous versions.
So I also fixed a whole category of other issues, mostly by moving error handling into FormulaInstaller. Now error's can be caught in Homebrew.install and handled on a formula-by-formula basis. I will next port this behaviour to upgrade.
Also adjust output text slightly for prettiness.
A possibly useful side effect here is safe_system has a defined Exception (subclassing RuntimeError) now.
`DownloadError` is an exception that download stratigies can throw to indicate
that a fetch was incomplete due to a failure in communication.
The `curl` method in `utils.rb` has been upgraded to throw a `DownloadError` if
something bad happens to `curl` execution.
The code was sucking. To the extent that maintenance was hard. It's a lot
easier to work with code that is sensibly split at sensible boundaries. So
now it is more like that.
But the refactor is minimal. Because we don't want you to have more merge
hell than absolutely necessary.
If you merge you will need to pay attention to brew.h.rb (as it is deleted)
and bin/brew (as command logic is gone). It will be painful, but you will just
have to help git out by moving any changes around manually.
Note compatibility.rb. It ensures that any function renames or removals don't
break anything. We're pretty serious about backwards compatibility. And that's
because we encourage you to hack around with the innards. And we couldn't do
that if we would then just make stuff disappear behind your back.
