On Jan 5, 2006, at 2:51 AM, Nicholas Rinard wrote:
how is this not a bug?
I thought when I read it that it acknowledged as a bug with a work
around. Get the ZipFile. So more accurately, yes a bug, but no, will
not get fixed. The central directory for the zip file is at the end
of the file or stream which is problematic for this access.
If you wanted information from the central directory without using
the java.util.zip code you could handle it as a RandomAccessFile and
use something like...
private void findDirFooter(RandomAccessFile raf,long length) throws
IOException
{
long seekPos = length - FixedSizeOfDirFooter;
if (seekPos < 0)
throw new IOException(zipPath + " central directory footer not
found");
raf.seek(seekPos);
for (int i = 0; i < 256; i++)
{
while (raf.readInt() != DIR_END) raf.seek(--seekPos);
footer = new ZipDirFooter(raf);
return;
}
// Messed up bad enough this doesn't attempt to checkpoint with
error()
throw new IOException(zipPath + " central directory footer not
found");
}
private void readCentralDir(RandomAccessFile raf,long length)
throws IOException
{
try { findDirFooter(raf,length); }
catch(EOFException eof) {
return;
}
long dirpos = (long)footer.centralDirOffset;
if (dirpos == 0) return; // If empty return
// Verify at dir, seeing some bad ones, else seek
raf.seek(dirpos);
int dirtest = raf.readInt();
if (dirtest != DIR) {
boolean dirfound = false;
for (;(++dirpos) < (raf.length()-4);) {
raf.seek(dirpos);
dirtest = raf.readInt();
if (dirtest == DIR) {
footer.setCentralDirOffset((int)dirpos); // Should update be
forced?
dirfound = true;
utillib.common.Configuration.getSysOut().println("ZipFile:
misplaced directory header found at " + dirpos + " for " + zipPath);
break;
}
}
// Even after locating correctly we now seem to corrupt worse, so
error as it used to be for now
throw new IOException("Directory header not found for " + zipPath);
}
raf.seek(dirpos);
int entries = (int)footer.getDirEntriesCnt();
for (int i = 0; i < entries; i++) {
int header = raf.readInt();
if (header != DIR) {
if (header == DIR_END) {
System.out.println("ZipFile: " + zipPath + " - Early directory
end with " + (i+1) + " of " + entries + " entries");
}
long savepos = rafzip.getFilePointer();
logger.error("ZipFile: " + zipPath + " - Error reading directory
got " + Integer.toHexString(header) + " instead of DIR at " +
Long.toHexString(savepos-4));
ZipFileUtils.dump(rafzip,(long)(rafzip.getFilePointer()-64)/
32*32,(long)128);
rafzip.seek(savepos); // In trouble anyhow but restore location
throw new IOException("Directory header not found");
}
ZipDirHeader dirHeader = new ZipDirHeader(raf);
dirList.put(dirHeader.getFileName(),dirHeader);
}
logger.debug("ZipFile: " + zipPath + " read central dir complete");
}
This my own code (some comments deleted, I've fought file corruption
with this code a number of times) , already mentioned if not
shamelessly plugged.
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