Added another tool used in dak (and placed nowhere else), dsync

[dak.git] / tools / dsync-0.0 / libdsync / contrib / slidingwindow.cc

diff --git a/tools/dsync-0.0/libdsync/contrib/slidingwindow.cc b/tools/dsync-0.0/libdsync/contrib/slidingwindow.cc
new file mode 100644 (file)
index 0000000..ad6cdd2
--- /dev/null
+++ b/tools/dsync-0.0/libdsync/contrib/slidingwindow.cc
@@ -0,0 +1,110 @@
+// -*- mode: cpp; mode: fold -*-
+// Description                                                         /*{{{*/
+// $Id: slidingwindow.cc,v 1.1 1999/11/05 05:47:06 jgg Exp $
+/* ######################################################################
+
+   Sliding Window - Implements a sliding buffer over a file. 
+
+   It would be possible to implement an alternate version if 
+   _POSIX_MAPPED_FILES is not defined.. 
+   
+   ##################################################################### */
+                                                                       /*}}}*/
+// Include files                                                       /*{{{*/
+#ifdef __GNUG__
+#pragma implementation "dsync/slidingwindow.h"
+#endif
+
+#include <dsync/slidingwindow.h>
+#include <dsync/error.h>
+
+#include <sys/mman.h>
+#include <unistd.h>
+                                                                       /*}}}*/
+
+// SlidingWindow::SlidingWindow - Constructor                          /*{{{*/
+// ---------------------------------------------------------------------
+/* */
+SlidingWindow::SlidingWindow(FileFd &Fd,unsigned long MnSize) : Buffer(0),
+                              MinSize(MnSize), Fd(Fd)
+{       
+   Offset = 0;
+   Left = 0;
+   PageSize = sysconf(_SC_PAGESIZE);
+      
+   if (MinSize < 1024*1024)
+      MinSize = 1024*1024;
+   MinSize = Align(MinSize);   
+}
+                                                                       /*}}}*/
+// SlidingWindow::~SlidingWindow - Destructor                          /*{{{*/
+// ---------------------------------------------------------------------
+/* Just unmap the mapping */
+SlidingWindow::~SlidingWindow()
+{
+   if (Buffer != 0)
+   {
+      if (munmap((char *)Buffer,Size) != 0)
+        _error->Warning("Unable to munmap");
+   }   
+}
+                                                                       /*}}}*/
+// SlidingWindow::Extend - Make Start - End longer                                                                     /*{{{*/
+// ---------------------------------------------------------------------
+/* Start == End when the file is exhausted, false is an IO error. */
+bool SlidingWindow::Extend(unsigned char *&Start,unsigned char *&End)
+{
+   unsigned long Remainder = 0;
+   
+   // Restart
+   if (Start == 0 || Buffer == 0)
+   {
+      Offset = 0;
+      Left = Fd.Size();
+   }
+   else
+   {
+      if (AlignDn((unsigned long)(Start - Buffer)) == 0)
+        return _error->Error("SlidingWindow::Extend called with too small a 'Start'");
+
+      // Scanning is finished.
+      if (Left < (off_t)Size)
+      {
+        End = Start;
+        return true;
+      }
+      
+      Offset += AlignDn((unsigned long)(Start - Buffer));
+      Left -= AlignDn((unsigned long)(Start - Buffer));
+      Remainder = (Start - Buffer) % PageSize;      
+   }
+
+   // Release the old region
+   if (Buffer != 0)
+   {
+      if (munmap((char *)Buffer,Size) != 0)
+        return _error->Errno("munmap","Unable to munmap");
+      Buffer = 0;
+   }
+
+   // Maximize the amount that can be mapped
+   if (Left < (off_t)MinSize)
+      Size = Align(Left);
+   else
+      Size = MinSize;
+   
+   // Map it
+   Buffer = (unsigned char *)mmap(0,Size,PROT_READ,MAP_PRIVATE,Fd.Fd(),Offset);
+   if (Buffer == (unsigned char *)-1)
+      return _error->Errno("mmap","Couldn't make mmap %lu->%lu bytes",(unsigned long)Offset,
+                          Size);
+   
+   // Reposition
+   if (Left < (off_t)Size)
+      End = Buffer + Left;
+   else
+      End = Buffer + Size;
+   Start = Buffer + Remainder;
+   return true;
+}
+                                                                       /*}}}*/