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# rpmbuild-order

This is a tool to sort RPM source packages in build dependency order.
This code is originally derived from
[cabal-sort](http://hackage.haskell.org/package/cabal-sort)
by Henning Thielemann.

## Usage

    $ rpmbuild-order --help
    :
    $ rpmbuild-order sort mycore mylib myapp
    mylib mycore myapp

The arguments passed can either be directories containing the package
or spec files.

If the dependency graph has cycles then an error will be output with
a list of cycles and any shortest path subcycles.

Using the rpmbuild-order `deps` and `rdeps` commands the ordered
dependencies and reverse dependencies of a package can be obtained
within the current set of checked out package sources.

The `render` command displays a graph of package dependencies
using graphviz and X11 or optionally instead prints the dot format to stdout.

## Library
As of version 0.4, a library is also provided.

There are two modules:

- `Distribution.RPM.Build.Graph` provides lower level functions for generating
  RPM dependency graphs
- `Distribution.RPM.Build.Order` provides higher level functions for
  sorting packages in build dependency orders and output.

Please see the documentation for more details.

## Notes and known problems
1. Given packages A, B, C, where C depends on B, and B depends on A,
and you call

    rpmbuild-order sort C.spec A.spec

then the output may be wrong if C does not have a direct dependency on A.
Even if the order is correct, B is missing in the output
and thus in this case the list of packages cannot be reliably used
for a sequence of builds.

However the `deps` and `rdeps` commands take
other neighbouring package directories into account.

2. repoquery is not used to resolve meta-dependencies or files to packages.
So if a package BuildRequires a file, it will not be resolved to a package.
This may get addressed some day, but file dependencies seem less common for
BuildRequires than Requires.

3. rpmspec is used to parse spec files (for macro expansion etc):
so missing macros packages can lead to erroneous results in some cases.