[REVIEW 3-5]: don't loose data on disk failure (fsync) fdo#40607

Hi guys,

        I'd love some thoughts on this. Of course, finding the right place to
put the osl_syncFile took a fair while, but then to discover that the
dp_manager was bootstrapping all that UCB-ness just to create and delete
a file, twice on startup each time ... we certainly can't be doing an
fsync on startup on old file-systems it'd be a killer, and just look
like an ultra-slow start.

        Anyhow - hopefully this will save someone some theoretical data, or at
least give a new idea of where to look for data-loss :-) I also tend to
loathe these 'vnd.expand' URLs. I wish we had a simple low-level API for
them we could use everywhere, that had the more complex (?)
configmgr-ness hooked into it at run-time. Anyhow - hopefully this
didn't break some ultra-complicated expansion use-case.

        Thoughts appreciated,

                Michael.

-- 
michael.meeks@suse.com  <><, Pseudo Engineer, itinerant idiot

From d3192948fe968fc4d6a8ec0e6fda232f265b3c4c Mon Sep 17 00:00:00 2001
From: Michael Meeks <michael.meeks@suse.com>
Date: Fri, 9 Mar 2012 17:02:32 +0000
Subject: [PATCH] fdo#40607 - osl_syncFile having written, and avoid doing
 that on start

---
 desktop/source/deployment/manager/dp_manager.cxx |   64 +++++++++++-----------
 ucb/source/ucp/file/shell.cxx                    |    4 ++
 2 files changed, 36 insertions(+), 32 deletions(-)

diff --git a/desktop/source/deployment/manager/dp_manager.cxx 
b/desktop/source/deployment/manager/dp_manager.cxx
index 4f6f6c04..0efa4c0 100644
--- a/desktop/source/deployment/manager/dp_manager.cxx
+++ b/desktop/source/deployment/manager/dp_manager.cxx
@@ -311,6 +311,36 @@ void PackageManagerImpl::initRegistryBackends()
                          m_xComponentContext ) );
 }
 
+// this overcomes previous rumours that the sal API is misleading
+// as to whether a directory is truly read-only or not
+static bool isMacroURLWriteable( const OUString &rMacro )
+{
+    if (rMacro.getLength() < (sal_Int32)sizeof ("vnd.sun.star.expand:"))
+        return true;
+    rtl::OUString aURL( rMacro.copy( sizeof ("vnd.sun.star.expand:") - 1 ) );
+    ::rtl::Bootstrap::expandMacros( aURL );
+
+    bool bError;
+    sal_uInt64 nWritten = 0;
+    ::osl::File aFile( aURL );
+
+    bError = aFile.open( osl_File_OpenFlag_Read |
+                         osl_File_OpenFlag_Write |
+                         osl_File_OpenFlag_Create ) != ::osl::FileBase::E_None;
+    if (!bError)
+        bError = aFile.write( "1", 1, nWritten ) != ::osl::FileBase::E_None;
+    if (aFile.close() != ::osl::FileBase::E_None)
+        bError = true;
+    if (osl::File::remove( aURL ) != ::osl::FileBase::E_None)
+        bError = true;
+
+    OSL_TRACE ("local url '%s' -> '%s' %s readonly\n",
+               rtl::OUStringToOString( rMacro, RTL_TEXTENCODING_UTF8 ).getStr(),
+               rtl::OUStringToOString( aURL, RTL_TEXTENCODING_UTF8 ).getStr(),
+               bError ? "is" : "is not");
+    return bError;
+}
+
 //______________________________________________________________________________
 Reference<deployment::XPackageManager> PackageManagerImpl::create(
     Reference<XComponentContext> const & xComponentContext,
@@ -406,39 +436,9 @@ Reference<deployment::XPackageManager> PackageManagerImpl::create(
     Reference<XCommandEnvironment> xCmdEnv;
 
     try {
-        //There is no stampURL for the bundled folder
+        // There is no stampURL for the bundled folder
         if (!stampURL.isEmpty())
-        {
-#define CURRENT_STAMP "1"
-            try {
-                //The osl file API does not allow to find out if one can write
-                //into a folder. Therefore we try to write a file. Then we delete
-                //it, so that it does not hinder uninstallation of OOo
-                // probe writing:
-                ::ucbhelper::Content ucbStamp( stampURL, xCmdEnv );
-                ::rtl::OString stamp(
-                    RTL_CONSTASCII_STRINGPARAM(CURRENT_STAMP) );
-                Reference<io::XInputStream> xData(
-                    ::xmlscript::createInputStream(
-                        ::rtl::ByteSequence(
-                            reinterpret_cast<sal_Int8 const *>(stamp.getStr()),
-                            stamp.getLength() ) ) );
-                ucbStamp.writeStream( xData, true /* replace existing */ );
-                that->m_readOnly = false;
-                erase_path( stampURL, xCmdEnv );
-            }
-            catch (const RuntimeException &) {
-                try {
-                    erase_path( stampURL, xCmdEnv );
-                } catch (...)
-                {
-                }
-                throw;
-            }
-            catch (const Exception &) {
-                that->m_readOnly = true;
-            }
-        }
+            that->m_readOnly = !isMacroURLWriteable( stampURL );
 
         if (!that->m_readOnly && !logFile.isEmpty())
         {
diff --git a/ucb/source/ucp/file/shell.cxx b/ucb/source/ucp/file/shell.cxx
index 725820d..86236f0 100644
--- a/ucb/source/ucp/file/shell.cxx
+++ b/ucb/source/ucp/file/shell.cxx
@@ -1909,6 +1909,10 @@ shell::write( sal_Int32 CommandId,
         }
     } while( nReadBytes == nRequestedBytes );
 
+    aFile.sync(); // fsync / flush it to disk.
+    OSL_TRACE( "fsync'd file '%s'\n",
+               rtl::OUStringToOString( aUnqPath, RTL_TEXTENCODING_UTF8 ).getStr() );
+
     err = aFile.close();
     if( err != osl::FileBase::E_None  )
     {
-- 
1.7.9