Add new rpm plugin (#1718)

Add a basic plugin to expose configuration information from the RPM
package manager. I specifically wrote this to expose the `_db_backend`
macro, but figured it'd be useful to make it cover a bit more while at
it.

This plugin is enabled on all non-Windows platforms, because a port of
RPM exists (and is sometimes used) on pretty much all platforms, even
where it's not usually installed by default.

Signed-off-by: Davide Cavalca <dcavalca@fb.com>

1 files changed, 109 insertions, 0 deletions

diff --git a/lib/ohai/plugins/rpm.rb b/lib/ohai/plugins/rpm.rb
new file mode 100644
index 00000000..7f4870b1
--- /dev/null
+++ b/lib/ohai/plugins/rpm.rb
@@ -0,0 +1,109 @@
+# frozen_string_literal: true
+
+#
+# Author:: Davide Cavalca <dcavalca@fb.com>
+# Copyright:: Copyright (c) 2021 Meta Platforms, Inc. and affiliates.
+# License:: Apache License, Version 2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+Ohai.plugin(:Rpm) do
+  provides "rpm"
+  optional "true"
+
+  MACROS_MARKER = /========================/.freeze
+
+  DO_NOT_SPLIT = %w{
+    build_arch
+    build_os
+    install_arch
+    install_os
+    archcolor
+    optflags
+  }.freeze
+
+  collect_data(:aix, :darwin, :dragonflybsd, :freebsd, :linux, :netbsd, :openbsd, :solaris2) do
+    rpm_path = which("rpm")
+    if rpm_path
+      rpm_version_out = shell_out("#{rpm_path} --version")
+      rpm_showrc_out = shell_out("#{rpm_path} --showrc")
+
+      rpm Mash.new unless rpm
+      rpm[:macros] ||= Mash.new
+
+      m = rpm_version_out.stdout.match(/\w+ (\d.*)/)
+      if m
+        rpm[:version] = m[1]
+      end
+
+      lines = rpm_showrc_out.stdout.split("\n")
+      # there's a marker to separate the beginning and end of the macros list
+      macros_start_idx = lines.index { |x| x.match(MACROS_MARKER) }
+      macros_end_idx = lines.rindex { |x| x.match(MACROS_MARKER) }
+      section = nil
+      lines[0..macros_start_idx - 1].each do |line|
+        if line.start_with?("ARCHITECTURE AND OS")
+          section = :arch_os
+          rpm[section] ||= Mash.new
+        elsif line.start_with?("RPMRC VALUES")
+          section = :rpmrc
+          rpm[section] ||= Mash.new
+        elsif line.start_with?("Features supported by rpmlib")
+          section = :features
+          rpm[section] ||= Mash.new
+        elsif line.start_with?("Macro path")
+          fields = line.split(":", 2)
+          if fields
+            rpm[:macro_path] = fields[1].strip.split(":")
+          end
+          section = nil
+        elsif %i{arch_os rpmrc}.include?(section)
+          fields = line.split(":")
+          if fields && fields[0] && fields[1]
+            key = fields[0].strip.sub("'s", "es").tr(" ", "_")
+            if DO_NOT_SPLIT.include?(key)
+              values = fields[1].strip
+            else
+              values = fields[1].strip.split(" ")
+            end
+            rpm[section][key] = values
+          end
+        elsif section == :features
+          fields = line.split("=")
+          if fields && fields[0] && fields[1]
+            rpm[section][fields[0].strip] = fields[1].strip
+          end
+        end
+      end
+
+      name = nil
+      value = ""
+      lines[macros_start_idx + 1..macros_end_idx - 1].each do |line|
+        if line.start_with?("-")
+          if name
+            rpm[:macros][name] = value
+            name = nil
+            value = ""
+          else
+            _prefix, name, value = line.split(" ", 3)
+          end
+        else
+          value += "\n#{line}"
+        end
+      end
+    else
+      logger.trace("Plugin RPM: Could not find rpm. Skipping plugin.")
+    end
+  end
+end