Disable --deferred-input when --save-session is used together

With --deferred-input=true, aria2 only reads input file to fill active
download slots, while keeping input file open.  Meanwhile,
--save-session saves all download info inside memory, but this does
not take into account of unread item in input file.  This will lead to
lose input data in saved session file.  Also current BufferedFile
implementation used to read/write input/output file take a lock on
Windows.  This effectively prevents session serializer from writing
session data to the same file which is still kept open because of
--deferred-input.  See GH-493

doc/manual-src/en/aria2c.rst

@@ -1207,6 +1207,11 @@ Advanced Options
   and options at startup.
   Default: ``false``
 
+  .. Warning::
+
+    :option:`--deferred-input` option will be disabled when
+    :option:`--save-session` is used together.
+
 .. option:: --disable-ipv6[=true|false]
 
   Disable IPv6. This is useful if you have to use broken DNS and want

src/Context.cc

@@ -278,16 +278,15 @@ Context::Context(bool standalone,
   // command-line. If they are left, because op is used as a template
   // for new RequestGroup(such as created in RPC command), they causes
   // unintentional effect.
-  for(auto i = op; i; i = i->getParent()) {
-    i->remove(PREF_OUT);
-    i->remove(PREF_FORCE_SEQUENTIAL);
-    i->remove(PREF_INPUT_FILE);
-    i->remove(PREF_INDEX_OUT);
-    i->remove(PREF_SELECT_FILE);
-    i->remove(PREF_PAUSE);
-    i->remove(PREF_CHECKSUM);
-    i->remove(PREF_GID);
-  }
+  op->remove(PREF_OUT);
+  op->remove(PREF_FORCE_SEQUENTIAL);
+  op->remove(PREF_INPUT_FILE);
+  op->remove(PREF_INDEX_OUT);
+  op->remove(PREF_SELECT_FILE);
+  op->remove(PREF_PAUSE);
+  op->remove(PREF_CHECKSUM);
+  op->remove(PREF_GID);
+
   if(standalone &&
      !op->getAsBool(PREF_ENABLE_RPC) && requestGroups.empty() &&
      !uriListParser) {

src/Option.cc

@@ -147,12 +147,20 @@ double Option::getAsDouble(PrefPtr pref) const {
   }
 }
 
-void Option::remove(PrefPtr pref)
+void Option::removeLocal(PrefPtr pref)
 {
   unsetBit(use_, pref);
   table_[pref->i].clear();
 }
 
+void Option::remove(PrefPtr pref)
+{
+  removeLocal(pref);
+  if (parent_) {
+    parent_->remove(pref);
+  }
+}
+
 void Option::clear()
 {
   std::fill(use_.begin(), use_.end(), 0);

src/Option.h

@@ -76,6 +76,8 @@ public:
   double getAsDouble(PrefPtr pref) const;
   // Removes |pref| from this object. This function does not modify
   // parent_.
+  void removeLocal(PrefPtr pref);
+  // Removes |pref| from this object from all option hierarchy.
   void remove(PrefPtr pref);
   // Removes all option values from this object. This function does
   // not modify parent_.

src/option_processing.cc

@@ -59,6 +59,7 @@
 #include "BufferedFile.h"
 #include "console.h"
 #include "array_fun.h"
+#include "LogFactory.h"
 #ifndef HAVE_DAEMON
 #include "daemon.h"
 #endif // !HAVE_DAEMON
@@ -331,6 +332,11 @@ error_code::Value option_processing(Option& op, bool standalone,
       return error_code::UNKNOWN_ERROR;
     }
   }
+  if (op.getAsBool(PREF_DEFERRED_INPUT) && op.defined(PREF_SAVE_SESSION)) {
+    A2_LOG_WARN("--deferred-input is disabled because of the presence of "
+                "--save-session");
+    op.remove(PREF_DEFERRED_INPUT);
+  }
   return error_code::FINISHED;
 }
 

test/OptionTest.cc

@@ -18,6 +18,7 @@ class OptionTest:public CppUnit::TestFixture {
   CPPUNIT_TEST(testBlank);
   CPPUNIT_TEST(testMerge);
   CPPUNIT_TEST(testParent);
+  CPPUNIT_TEST(testRemove);
   CPPUNIT_TEST_SUITE_END();
 private:
 
@@ -32,6 +33,7 @@ public:
   void testBlank();
   void testMerge();
   void testParent();
+  void testRemove();
 };
 
 
@@ -118,9 +120,31 @@ void OptionTest::testParent()
   CPPUNIT_ASSERT(child.defined(PREF_TIMEOUT));
   CPPUNIT_ASSERT(child.definedLocal(PREF_TIMEOUT));
   CPPUNIT_ASSERT_EQUAL(std::string("200"), child.get(PREF_TIMEOUT));
-  child.remove(PREF_TIMEOUT);
+  child.removeLocal(PREF_TIMEOUT);
   CPPUNIT_ASSERT(child.defined(PREF_TIMEOUT));
   CPPUNIT_ASSERT(!child.definedLocal(PREF_TIMEOUT));
 }
 
+void OptionTest::testRemove()
+{
+  Option child;
+  auto parent = std::make_shared<Option>();
+  child.setParent(parent);
+
+  child.put(PREF_DIR, "foo");
+  child.put(PREF_TIMEOUT, "200");
+  parent->put(PREF_DIR, "bar");
+  parent->put(PREF_TIMEOUT, "400");
+
+  child.remove(PREF_DIR);
+
+  CPPUNIT_ASSERT(!child.defined(PREF_DIR));
+
+  child.removeLocal(PREF_TIMEOUT);
+
+  CPPUNIT_ASSERT(!child.definedLocal(PREF_TIMEOUT));
+  CPPUNIT_ASSERT(child.defined(PREF_TIMEOUT));
+  CPPUNIT_ASSERT(parent->defined(PREF_TIMEOUT));
+}
+
 } // namespace aria2