[
https://issues.apache.org/jira/browse/COMPRESS-497?focusedWorklogId=337716&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-337716
]
ASF GitHub Bot logged work on COMPRESS-497:
-------------------------------------------
Author: ASF GitHub Bot
Created on: 02/Nov/19 16:13
Start Date: 02/Nov/19 16:13
Worklog Time Spent: 10m
Work Description: bodewig commented on pull request #85: COMPRESS-497
Handle missing endheader offset
URL: https://github.com/apache/commons-compress/pull/85#discussion_r341816574
##########
File path:
src/main/java/org/apache/commons/compress/archivers/sevenz/SevenZFile.java
##########
@@ -441,17 +441,81 @@ private Archive readHeaders(final byte[] password)
throws IOException {
archiveVersionMajor, archiveVersionMinor));
}
+ boolean headerLooksValid = false; // See
https://www.7-zip.org/recover.html - "There is no correct End Header at the end
of archive"
final long startHeaderCrc = 0xffffFFFFL & buf.getInt();
- final StartHeader startHeader = readStartHeader(startHeaderCrc);
+ if (startHeaderCrc == 0) {
+ // This is an indication of a corrupt header - peek the next 20
bytes
+ long currentPosition = channel.position();
+ ByteBuffer peekBuf = ByteBuffer.allocate(20);
+ readFully(peekBuf);
+ channel.position(currentPosition);
+ // Header invalid if all data is 0
+ while (peekBuf.hasRemaining()) {
+ if (peekBuf.get()!=0) {
+ headerLooksValid = true;
+ break;
+ }
+ }
+ } else {
+ headerLooksValid = true;
+ }
+
+ if (headerLooksValid) {
+ final StartHeader startHeader = readStartHeader(startHeaderCrc);
+ return initializeArchive(startHeader, password, true);
+ } else {
+ // No valid header found - probably first file of multipart
archive was removed too early. Scan for end header.
Review comment:
actually I can do this kind of cosmetic change myself, :-)
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Issue Time Tracking
-------------------
Worklog Id: (was: 337716)
Time Spent: 40m (was: 0.5h)
> Handle missing offset to end header in 7z
> -----------------------------------------
>
> Key: COMPRESS-497
> URL: https://issues.apache.org/jira/browse/COMPRESS-497
> Project: Commons Compress
> Issue Type: Improvement
> Components: Archivers
> Reporter: Stefan Schlott
> Priority: Major
> Time Spent: 40m
> Remaining Estimate: 0h
>
> When dealing with multipart 7z files, it may occur that the start header is
> invalid (all zeros) - see [https://www.7-zip.org/recover.html], section
> "There is no correct End Header at the end of archive". This can happen if
> the first part of the file is moved while the overall operation hasn't
> finished yet (the start header is written as very last step).
> Detect a missing start header (all bytes are zero) and try to guess the end
> header.
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