Merge pull request #4949 from MikeMcQuaid/dbm_crash

cache_store: handle corrupt DBM database.

Library/Homebrew/cache_store.rb

@@ -1,5 +1,6 @@
 require "dbm"
 require "json"
+require "timeout"
 
 #
 # `CacheStoreDatabase` acts as an interface to a persistent storage mechanism
@@ -46,7 +47,7 @@ class CacheStoreDatabase
   #
   # @return [Boolean]
   def created?
-    File.exist?(cache_path)
+    cache_path.exist?
   end
 
   private
@@ -57,6 +58,10 @@ class CacheStoreDatabase
   #   https://docs.oracle.com/cd/E17276_01/html/api_reference/C/envopen.html
   DATABASE_MODE = 0664
 
+  # Spend 5 seconds trying to read the DBM file. If it takes longer than this it
+  # has likely hung or segfaulted.
+  DBM_TEST_READ_TIMEOUT = 5
+
   # Lazily loaded database in read/write mode. If this method is called, a
   # database file with be created in the `HOMEBREW_CACHE` with name
   # corresponding to the `@type` instance variable
@@ -66,6 +71,29 @@ class CacheStoreDatabase
     # DBM::WRCREAT: Creates the database if it does not already exist
     @db ||= begin
       HOMEBREW_CACHE.mkpath
+      if created?
+        dbm_test_read_cmd = SystemCommand.new(
+          ENV["HOMEBREW_RUBY_PATH"],
+          args: [
+            "-rdbm",
+            "-e",
+            "DBM.open('#{dbm_file_path}', #{DATABASE_MODE}, DBM::READER).size",
+          ],
+          print_stderr: false,
+          must_succeed: true,
+        )
+        dbm_test_read_success = begin
+          Timeout.timeout(DBM_TEST_READ_TIMEOUT) do
+            dbm_test_read_cmd.run!
+            true
+          end
+        rescue ErrorDuringExecution, Timeout::Error
+          odebug "Failed to read #{dbm_file_path}!"
+          Process.kill(:KILL, dbm_test_read_cmd.pid)
+          false
+        end
+        cache_path.delete unless dbm_test_read_success
+      end
       DBM.open(dbm_file_path, DATABASE_MODE, DBM::WRCREAT)
     end
   end
@@ -83,7 +111,7 @@ class CacheStoreDatabase
   #
   # @return [String]
   def dbm_file_path
-    File.join(HOMEBREW_CACHE, @type.to_s)
+    "#{HOMEBREW_CACHE}/#{@type}"
   end
 
   # The path where the database resides in the `HOMEBREW_CACHE` for the given
@@ -91,7 +119,7 @@ class CacheStoreDatabase
   #
   # @return [String]
   def cache_path
-    "#{dbm_file_path}.db"
+    Pathname("#{dbm_file_path}.db")
   end
 end
 

Library/Homebrew/system_command.rb

@@ -19,6 +19,8 @@ end
 class SystemCommand
   extend Predicable
 
+  attr_reader :pid
+
   def self.run(executable, **options)
     new(executable, **options).run!
   end
@@ -122,6 +124,7 @@ class SystemCommand
 
     raw_stdin, raw_stdout, raw_stderr, raw_wait_thr =
       Open3.popen3(env, [executable, executable], *args, **options)
+    @pid = raw_wait_thr.pid
 
     write_input_to(raw_stdin)
     raw_stdin.close_write
@@ -191,6 +194,7 @@ class SystemCommand
     end
 
     def success?
+      return false if @exit_status.nil?
       @exit_status.zero?
     end
 

Library/Homebrew/test/cache_store_spec.rb

@@ -118,15 +118,15 @@ describe CacheStoreDatabase do
   end
 
   describe "#created?" do
-    let(:cache_path) { "path/to/homebrew/cache/sample.db" }
+    let(:cache_path) { Pathname("path/to/homebrew/cache/sample.db") }
 
     before(:each) do
       allow(subject).to receive(:cache_path).and_return(cache_path)
     end
 
-    context "`File.exist?(cache_path)` returns `true`" do
+    context "`cache_path.exist?` returns `true`" do
       before(:each) do
-        allow(File).to receive(:exist?).with(cache_path).and_return(true)
+        allow(cache_path).to receive(:exist?).and_return(true)
       end
 
       it "returns `true`" do
@@ -134,9 +134,9 @@ describe CacheStoreDatabase do
       end
     end
 
-    context "`File.exist?(cache_path)` returns `false`" do
+    context "`cache_path.exist?` returns `false`" do
       before(:each) do
-        allow(File).to receive(:exist?).with(cache_path).and_return(false)
+        allow(cache_path).to receive(:exist?).and_return(false)
       end
 
       it "returns `false`" do

Library/Homebrew/utils/ruby.sh

@@ -47,7 +47,7 @@ setup-ruby-path() {
         then
           odie "Failed to install vendor Ruby."
         fi
-        rm -rf "$vendor_dir/bundle/ruby" "$HOMEBREW_CACHE/linkage.db"
+        rm -rf "$vendor_dir/bundle/ruby"
         HOMEBREW_RUBY_PATH="$vendor_ruby_path"
       fi
     fi