1 files changed, 131 insertions, 0 deletions
diff --git a/packedstorage.c b/packedstorage.c
new file mode 100644
index 0000000..f23866f
--- /dev/null
+++ b/packedstorage.c
@@ -0,0 +1,131 @@
+/*************************************************************** -*- c++ -*-
+ *       Copyright (c) 2003,2004 by Marcel Wiesweg                         *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "packedstorage.h"
+
+PackedStorage::PackedStorage(int maxMB)
+ : LegacyStorage(maxMB) {
+}
+#define TOC_SIZE 8
+//The file structure is simple:
+// TOC_SIZE*PageAddress contains the numbers of the following pages
+// TOC_SIZE*TELETEXT_PAGESIZE contains the page data
+//and the same again.
+bool PackedStorage::seekTo(PageID page, int desc, bool create) {
+   lseek(desc, 0, SEEK_SET);
+   PageAddress addr[TOC_SIZE];
+
+   while (::read(desc, addr, sizeof(addr)) == sizeof(addr)) {
+      lseek(desc, 0, SEEK_CUR);
+      for (int index=0; index<TOC_SIZE; index++) {
+         if (addr[index]==page) {
+            lseek(desc, index*TELETEXT_PAGESIZE, SEEK_CUR);
+            return true;
+         } else if (addr[index].page==0) {
+            //0 means: no more pages follow
+            if (create) {
+               //rewind what was read
+               lseek(desc, -(off_t)sizeof(addr), SEEK_CUR);
+               //update index
+               addr[index]=page;
+               if (::write(desc, addr, sizeof(addr)) != sizeof(addr))
+                  return false;
+               //seek to data position
+               lseek(desc, TELETEXT_PAGESIZE*index, SEEK_CUR);
+               return true;
+            } else
+               return false;
+         }
+      }
+
+      //seek over data area
+      lseek(desc, TELETEXT_PAGESIZE*TOC_SIZE, SEEK_CUR);
+   }
+
+   int oldSize=actualFileSize(lseek(desc, 0, SEEK_CUR));
+   if (create) {
+      //create a new set of a TOC and a TOC_SIZE*TELETEXT_PAGESIZE data area
+      memset(addr, 0, sizeof(addr));
+      //first entry is our page
+      addr[0]=page;
+      if (::write(desc, addr, sizeof(addr)) != sizeof(addr))
+         return false;
+      //seek beyond end of file
+      lseek(desc, (TELETEXT_PAGESIZE*TOC_SIZE)-1, SEEK_CUR);
+      //write one byte to enlarge the file to the sought position
+      char c=1;
+      if (::write(desc, &c, 1) != 1)
+         return false;
+      //Now, calculate new file size
+      byteCount += ( actualFileSize(lseek(desc, 0, SEEK_CUR)) - oldSize );
+      //seek to beginning of data, which is requested
+      lseek(desc, -(off_t)(TELETEXT_PAGESIZE*TOC_SIZE), SEEK_CUR);
+      return true;
+   } else
+      return false;
+}
+
+void PackedStorage::getFilename(char *buffer, int bufLength, PageID page) {
+   //This is a different scheme: page 576_07 will have the name 570s.vtx, the same as e.g. 571_01 or 575_00
+   //Think of "the five hundred seventies"
+   snprintf(buffer, bufLength, "%s/%s/%03xs.vtx", getRootDir(),
+            *page.channel.ToString(), (page.page & 0xFF0));
+}
+
+StorageHandle PackedStorage::openForWriting(PageID page) {
+   static bool wroteError=false;
+   char filename[PATH_MAX];
+   getFilename(filename, sizeof(filename), page);
+   //first try
+   int desc=open(filename, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+   if (desc != -1) {
+      if (!seekTo(page, desc, true)) {
+         ::close(desc);
+         return StorageHandle();
+      }
+      if ( maxBytes && byteCount>maxBytes )
+         freeSpace();
+      return (StorageHandle)desc;
+   }
+   //no space on disk? make some space available
+   if (errno == ENOSPC)
+      freeSpace();
+   //second try
+   desc=open(filename, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+   if (desc==-1 && !wroteError) {
+      //report error to syslog - once!
+      wroteError=true;
+      esyslog("OSD-Teletext: Error opening teletext file %s: %s", filename, strerror(errno));
+   }
+
+   if (desc==-1)
+      return StorageHandle();
+   else if (!seekTo(page, desc, true)) {
+      ::close(desc);
+      return StorageHandle();
+   }
+
+   if ( maxBytes && byteCount>maxBytes )
+      freeSpace();
+   return (StorageHandle)desc;
+}
+
+StorageHandle PackedStorage::openForReading(PageID page, bool countAsAccess) {
+   int desc;
+   if ( (desc=(int)LegacyStorage::openForReading(page, false))!= -1 ) {
+      if (!seekTo(page, desc, false)) {
+         //this is not an error condition here, may and shall happen!
+         ::close(desc);
+      } else {
+         return (StorageHandle)desc;
+      }
+   }
+   return StorageHandle();
+}