Add strace_me, a simple strace(1) wrapper

drbrain · Jun 7, 2010 · d87ecda · d87ecda
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diff --git a/.autotest b/.autotest
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+# -*- ruby -*-
+
+require 'autotest/restart'
+
+Autotest.add_hook :initialize do |at|
+  at.testlib = 'minitest/unit'
+end
+
diff --git a/.gitignore b/.gitignore
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+/TAGS
+/pkg
+/doc
+*.swp
diff --git a/History.txt b/History.txt
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+=== 1.0.0 / 2010-06-07
+
+* Major Enhancement
+  * Birthday!
+
diff --git a/Manifest.txt b/Manifest.txt
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+History.txt
+Manifest.txt
+README.txt
+Rakefile
+lib/strace.rb
diff --git a/README.txt b/README.txt
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+= strace_me
+
+* http://seattlerb.rubyforge.org/strace_me
+
+== DESCRIPTION:
+
+A wrapper around strace(1) that allows you to perform targetted tracing of a
+block.  strace_me allows you to track down problems without wading through
+gobs of ruby startup or other irrelevant noise.
+
+== FEATURES/PROBLEMS:
+
+* strace only
+
+== SYNOPSIS:
+
+See Strace::me
+
+== REQUIREMENTS:
+
+* strace
+
+== INSTALL:
+
+* sudo gem install strace_me
+
+== LICENSE:
+
+(The MIT License)
+
+Copyright (c) 2010 Eric Hodel
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+'Software'), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/Rakefile b/Rakefile
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+# -*- ruby -*-
+
+require 'rubygems'
+require 'hoe'
+
+Hoe.plugin :git
+Hoe.plugin :minitest
+
+Hoe.spec 'strace_me' do
+  self.rubyforge_name = 'seattlerb'
+  developer 'Eric Hodel', 'drbrain@segment7.net'
+
+  extra_deps << ['open4', '~> 0.9']
+end
+
+# vim: syntax=Ruby
diff --git a/lib/strace.rb b/lib/strace.rb
@@ -0,0 +1,62 @@
+require 'open4'
+
+##
+# Simple wrapper of strace(1) for targetted tracing.
+
+module Strace
+
+  ##
+  # The version of strace_me you're using
+
+  VERSION = '1.0'
+
+  ##
+  # Runs strace(1) during the code in the block and returns an IO containing
+  # the strace output and the exception raised by the block (if any).
+  #
+  # Simple example (it doesn't matter if you have a /COPYRIGHT):
+  #
+  #   trace, err = Strace.me do
+  #     open '/COPYRIGHT' do |io|
+  #       io.read 1024
+  #     end
+  #   end
+  #
+  #   puts "error: #{err.message} (#{err.class})\n\n" if err
+  #   puts "trace:\n\n#{trace.read}"
+  #
+  # Tracing an existing library call:
+  #
+  #   alias old_connect connect
+  #
+  #   def connect host, user, password
+  #     connection = nil
+  #
+  #     trace, err = Strace.me do
+  #       connection = old_connect host, user, password
+  #     end
+  #
+  #     $stderr.puts "connect trace:\n\n#{trace.read}"
+  #
+  #     raise err if err
+  #     connection
+  #   end
+
+  def self.me
+    pid, i, o, e = Open4.open4 'strace', '-p', $$.to_s
+
+    i.close
+    e.gets # consumes "attached" message, but we know strace is ready
+
+    begin
+      yield
+    ensure
+      Process.kill 'INT', pid
+      Process.waitpid pid
+
+      return [e, $!]
+    end
+  end
+
+end
+
diff --git a/test/test_strace.rb b/test/test_strace.rb
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+require 'rubygems'
+require 'minitest/autorun'
+require 'strace'
+
+class TestStrace < MiniTest::Unit::TestCase
+
+  def test_class_me_no_strace
+    path = ENV['PATH']
+    ENV['PATH'] = nil
+
+    assert_raises Errno::ENOENT do
+      Strace.me do end
+    end
+
+  ensure
+    ENV['PATH'] = path
+  end
+
+end
+