Auto merge of #4765 - mistydemeo:linkage, r=indirect

WIP: add command to check dynamic library linkage

This new command, linkage, checks for broken dynamic library links in C extensions.

I'd heard there was some interest in adding this functionality, so I thought I'd submit a preliminary PR for discussion. In my experience, broken dylib linkage is a common issue with C extensions, so I think having a good way to diagnose it would be valuable.

This command scans all of the specifications in the bundle for .bundle files in C extensions. If any of the dynamic libraries linked against no longer exist, bundler will report a message to the console and exit non-0.

TODOs:
* Add support for non-Darwin OSs
* Improve tests

A few questions:

* Is there a good way to mock functionality in the tests? Doing it in the standard rspec way isn't working since `bundle :command` runs in a subprocess. I'd like to be able to stub out stuff that actually checks dylibs and the like.
* Is making this a new command the right approach? I assumed this wouldn't be ideal to include in, say, `check` because it would slow it down.

1 files changed, 95 insertions, 0 deletions

diff --git a/lib/bundler/cli/doctor.rb b/lib/bundler/cli/doctor.rb
new file mode 100644
index 00000000..8fd862a1
--- /dev/null
+++ b/lib/bundler/cli/doctor.rb
@@ -0,0 +1,95 @@
+# frozen_string_literal: true
+
+require "rbconfig"
+
+module Bundler
+  class CLI::Doctor
+    DARWIN_REGEX = /\s+(.+) \(compatibility /
+    LDD_REGEX = /\t\S+ => (\S+) \(\S+\)/
+
+    attr_reader :options
+
+    def initialize(options)
+      @options = options
+    end
+
+    def otool_available?
+      system("otool --version 2>&1 >#{Bundler::NULL}")
+    end
+
+    def ldd_available?
+      !system("ldd --help 2>&1 >#{Bundler::NULL}").nil?
+    end
+
+    def dylibs_darwin(path)
+      output = `/usr/bin/otool -L "#{path}"`.chomp
+      dylibs = output.split("\n")[1..-1].map {|l| l.match(DARWIN_REGEX).captures[0] }.uniq
+      # ignore @rpath and friends
+      dylibs.reject {|dylib| dylib.start_with? "@" }
+    end
+
+    def dylibs_ldd(path)
+      output = `/usr/bin/ldd "#{path}"`.chomp
+      output.split("\n").map do |l|
+        match = l.match(LDD_REGEX)
+        next if match.nil?
+        match.captures[0]
+      end.compact
+    end
+
+    def dylibs(path)
+      case RbConfig::CONFIG["host_os"]
+      when /darwin/
+        return [] unless otool_available?
+        dylibs_darwin(path)
+      when /(linux|solaris|bsd)/
+        return [] unless ldd_available?
+        dylibs_ldd(path)
+      else # Windows, etc.
+        Bundler.ui.warn("Dynamic library check not supported on this platform.")
+        []
+      end
+    end
+
+    def bundles_for_gem(spec)
+      Dir.glob("#{spec.full_gem_path}/**/*.bundle")
+    end
+
+    def run
+      Bundler.ui.level = "error" if options[:quiet]
+
+      broken_links = {}
+
+      begin
+        definition = Bundler.definition
+        definition.validate_ruby!
+        not_installed = definition.missing_specs
+        raise GemNotFound if not_installed.any?
+      rescue GemNotFound
+        Bundler.ui.warn "This bundle's gems must be installed to run this command."
+        Bundler.ui.warn "Install missing gems with `bundle install`."
+        exit 0
+      end
+
+      definition.specs.each do |spec|
+        bundles_for_gem(spec).each do |bundle|
+          bad_paths = dylibs(bundle).select {|f| !File.exist?(f) }
+          if bad_paths.any?
+            broken_links[spec] ||= []
+            broken_links[spec].concat(bad_paths)
+          end
+        end
+      end
+
+      if broken_links.any?
+        Bundler.ui.error "The following gems are missing OS dependencies"
+        broken_links.each do |spec, paths|
+          paths.uniq.each do |path|
+            Bundler.ui.error " * #{spec.name}: #{path}"
+          end
+        end
+        exit 1
+      end
+    end
+  end
+end