Changeset 28689 in vbox

Timestamp:

Apr 24, 2010 6:23:57 PM (15 years ago)

Author:

vboxsync

Message:

XmlFileWrite::write: Added a fSafe argument for safe writing of the xml file. See method description for details.

Location:

trunk

Files:

• include/iprt/cpp/xml.h (modified) (7 diffs)
• src/VBox/Main/ApplianceImplExport.cpp (modified) (1 diff)
• src/VBox/Main/xml/Settings.cpp (modified) (2 diffs)
• src/VBox/Runtime/r3/xml.cpp (modified) (10 diffs)

trunk/include/iprt/cpp/xml.h

@@ -1 +1 @@
 /** @file
- * VirtualBox XML helper APIs.
+ * IPRT - XML Helper APIs.
  */
 
 /*
- * Copyright (C) 2007-2009 Sun Microsystems, Inc.
+ * Copyright (C) 2007-2010 Sun Microsystems, Inc.
  *
  * This file is part of VirtualBox Open Source Edition (OSE), as
@@ -28 +28 @@
  */
 
-#ifndef ___VBox_vboxxml_h
-#define ___VBox_vboxxml_h
+#ifndef ___iprt_xml_h
+#define ___iprt_xml_h
 
 #ifndef IN_RING3
@@ -288 +288 @@
      * @param aMode     File mode.
      * @param aFileName File name.
-     */
-    File(Mode aMode, const char *aFileName);
+     * @param aFlushIt  Whether to flush a writable file before closing it.
+     */
+    File(Mode aMode, const char *aFileName, bool aFlushIt = false);
 
     /**
@@ -308 +309 @@
      * @param aHandle   Open file handle.
      * @param aFileName File name (for reference).
-     */
-    File(RTFILE aHandle, const char *aFileName = NULL);
+     * @param aFlushIt  Whether to flush a writable file before closing it.
+     */
+    File(RTFILE aHandle, const char *aFileName = NULL, bool aFlushIt = false);
 
     /**
@@ -669 +671 @@
     ~XmlFileWriter();
 
-    void write(const char *pcszFilename);
+    /**
+     * Writes the XML document to the specified file.
+     *
+     * @param   pcszFilename    The name of the output file.
+     * @param   fSafe           If @c true, some extra safety precautions will be
+     *                          taken when writing the file:
+     *                              -# The file is written with a '-tmp' suffix.
+     *                              -# It is flushed to disk after writing.
+     *                              -# Any original file is renamed to '-prev'.
+     *                              -# The '-tmp' file is then renamed to the
+     *                                 specified name.
+     *                              -# The directory changes are flushed to disk.
+     */
+    void write(const char *pcszFilename, bool fSafe);
 
     static int WriteCallback(void *aCtxt, const char *aBuf, int aLen);
@@ -675 +690 @@
 
 private:
+    void writeInternal(const char *pcszFilename, bool fSafe);
+
     /* Obscure class data */
     struct Data;
@@ -688 +705 @@
 } // end namespace xml
 
-#endif /* ___VBox_vboxxml_h */
+#endif /* !___iprt_xml_h */

trunk/src/VBox/Main/ApplianceImplExport.cpp

@@ -1548 +1548 @@
         // now go write the XML
         xml::XmlFileWriter writer(doc);
-        writer.write(locInfo.strPath.c_str());
+        writer.write(locInfo.strPath.c_str(), false /*fSafe*/);
 
         /* Create & write the manifest file */

trunk/src/VBox/Main/xml/Settings.cpp

@@ -1293 +1293 @@
     // now go write the XML
     xml::XmlFileWriter writer(*m->pDoc);
-    writer.write(m->strFilename.c_str());
+    writer.write(m->strFilename.c_str(), true /*fSafe*/);
 
     m->fFileExists = true;
@@ -4051 +4051 @@
         // now go write the XML
         xml::XmlFileWriter writer(*m->pDoc);
-        writer.write(m->strFilename.c_str());
+        writer.write(m->strFilename.c_str(), true /*fSafe*/);
 
         m->fFileExists = true;

trunk/src/VBox/Runtime/r3/xml.cpp

@@ +1 @@
+/* $Id$ */
 /** @file
- * VirtualBox XML Manipulation API.
+ * IPRT - XML Manipulation API.
  */
 
 /*
- * Copyright (C) 2007-2009 Sun Microsystems, Inc.
+ * Copyright (C) 2007-2010 Sun Microsystems, Inc.
  *
  * This file is part of VirtualBox Open Source Edition (OSE), as
@@ -28 +29 @@
  */
 
-#include <iprt/cdefs.h>
+#include <iprt/dir.h>
+#include <iprt/file.h>
 #include <iprt/err.h>
-#include <iprt/file.h>
+#include <iprt/param.h>
+#include <iprt/path.h>
 #include <iprt/cpp/lock.h>
 #include <iprt/cpp/xml.h>
@@ -179 +182 @@
     RTFILE handle;
     bool opened : 1;
+    bool flushOnClose : 1;
 };
 
-File::File(Mode aMode, const char *aFileName)
+File::File(Mode aMode, const char *aFileName, bool aFlushIt /* = false */)
     : m(new Data())
 {
     m->strFileName = aFileName;
+    m->flushOnClose = aFlushIt;
 
     uint32_t flags = 0;
@@ -208 +213 @@
 
     m->opened = true;
-}
-
-File::File(RTFILE aHandle, const char *aFileName /* = NULL */)
+    m->flushOnClose = aFlushIt && (flags & RTFILE_O_ACCESS_MASK) != RTFILE_O_READ;
+}
+
+File::File(RTFILE aHandle, const char *aFileName /* = NULL */, bool aFlushIt /* = false */)
     : m(new Data())
 {
     if (aHandle == NIL_RTFILE)
-        throw EInvalidArg (RT_SRC_POS);
+        throw EInvalidArg(RT_SRC_POS);
 
     m->handle = aHandle;
@@ -221 +227 @@
         m->strFileName = aFileName;
 
-    setPos (0);
+    m->flushOnClose = aFlushIt;
+
+    setPos(0);
 }
 
 File::~File()
 {
+    if (m->flushOnClose)
+    {
+        RTFileFlush(m->handle);
+        if (!m->strFileName.isEmpty())
+            RTDirFlushParent(m->strFileName.c_str());
+    }
+
     if (m->opened)
         RTFileClose(m->handle);
@@ -253 +268 @@
 
     /* check if we overflow int64_t and move to INT64_MAX first */
-    if (((int64_t) aPos) < 0)
+    if ((int64_t)aPos < 0)
     {
         vrc = RTFileSeek(m->handle, INT64_MAX, method, &p);
@@ -1360 +1375 @@
     iprt::MiniString error;
 
-    IOContext(const char *pcszFilename, File::Mode mode)
-        : file(mode, pcszFilename)
+    IOContext(const char *pcszFilename, File::Mode mode, bool fFlush = false)
+        : file(mode, pcszFilename, fFlush)
     {
     }
@@ -1386 +1401 @@
 struct WriteContext : IOContext
 {
-    WriteContext(const char *pcszFilename)
-        : IOContext(pcszFilename, File::Mode_Overwrite)
+    WriteContext(const char *pcszFilename, bool fFlush)
+        : IOContext(pcszFilename, File::Mode_Overwrite, fFlush)
     {
     }
@@ -1473 +1488 @@
 }
 
-void XmlFileWriter::write(const char *pcszFilename)
-{
-    WriteContext context(pcszFilename);
+void XmlFileWriter::writeInternal(const char *pcszFilename, bool fSafe)
+{
+    WriteContext context(pcszFilename, fSafe);
 
     GlobalLock lock;
@@ -1507 +1522 @@
 }
 
+void XmlFileWriter::write(const char *pcszFilename, bool fSafe)
+{
+    if (!fSafe)
+        writeInternal(pcszFilename, fSafe);
+    else
+    {
+        /* Empty string and directory spec must be avoid. */
+        if (RTPathFilename(pcszFilename) == NULL)
+            throw xml::LogicError(RT_SRC_POS);
+
+        /* Construct both filenames first to ease error handling.  */
+        char szTmpFilename[RTPATH_MAX];
+        int rc = RTStrCopy(szTmpFilename, sizeof(szTmpFilename) - sizeof("-tmp") + 1, pcszFilename);
+        if (RT_FAILURE(rc))
+            throw EIPRTFailure(rc, "RTStrCopy");
+        strcat(szTmpFilename, "-tmp");
+
+        char szPrevFilename[RTPATH_MAX];
+        rc = RTStrCopy(szPrevFilename, sizeof(szPrevFilename) - sizeof("-prev") + 1, pcszFilename);
+        if (RT_FAILURE(rc))
+            throw EIPRTFailure(rc, "RTStrCopy");
+        strcat(szPrevFilename, "-prev");
+
+        /* Write the XML document to the temporary file.  */
+        writeInternal(szTmpFilename, fSafe);
+
+        /* Make a backup of any existing file (ignore failure). */
+        uint64_t cbPrevFile;
+        rc = RTFileQuerySize(pcszFilename, &cbPrevFile);
+        if (RT_SUCCESS(rc) && cbPrevFile >= 16)
+            RTFileRename(pcszFilename, szPrevFilename, RTPATHRENAME_FLAGS_REPLACE);
+
+        /* Commit the temporary file. Just leave the tmp file behind on failure. */
+        rc = RTFileRename(szTmpFilename, pcszFilename, RTPATHRENAME_FLAGS_REPLACE);
+        if (RT_FAILURE(rc))
+            throw EIPRTFailure(rc, "Failed to replace '%s' with '%s'", pcszFilename, szTmpFilename);
+
+        /* Flush the directory changes (required on linux at least). */
+        RTPathStripFilename(szTmpFilename);
+        rc = RTDirFlush(szTmpFilename);
+        AssertMsg(RT_SUCCESS(rc) || rc == VERR_NOT_SUPPORTED || rc == VERR_NOT_IMPLEMENTED, ("%Rrc\n", rc));
+    }
+}
+
 int XmlFileWriter::WriteCallback(void *aCtxt, const char *aBuf, int aLen)
 {