What’s new in Undo 9.2 for C, C++, Go and Rust

See the sections below for the headline product improvements in Undo 9.2.

Improvements in UDB

All Undo users are licensed to use UDB, Undo’s interactive time travel debugger. Release 9.2 benefits from the improvements listed below.

Program history can now be navigated using percentage values

Operations that take time arguments can now use percentages of execution history. This makes it easy to navigate quickly across a recording to get an overview of what is happening at different points in the program, and is useful for bisecting or performing a binary search across program execution.

The ugo time command can now take you to a specific percentage of history:

50% 110,576> ugo time 25%

You can also move relative to where you are by a percentage of history:

25% 55,288> ugo time +10%

The info events, info wallclock, set time-limits min and set time-limits max commands also accept percentages.

New undo recording-check tool for verifying recording integrity

The new undo recording-check command verifies that an Undo recording is intact and has not been corrupted or truncated, for example after copying a recording between machines or after a network transfer. The tool performs a number of checks on the recording file, including:

  • verifying that the recording header is valid and complete;

  • checking that the table of contents exists and is accessible;

  • validating that all blocks referenced in the table of contents are present and readable;

  • ensuring that replayables have the required data structures;

  • detecting truncation by checking that block offsets and sizes are within file bounds.

Unlike other Undo recording tools, undo recording-check is designed to be used in automated workflows (for example, in CI pipelines) to validate recordings after they have been transferred or stored.

$ undo recording-check recording.undo
$ echo $?
0

$ undo recording-check bad.undo
Recording is truncated.
$ echo $?
1

A non-zero exit code indicates that the recording is invalid.

More…

Further product changes relating to UDB are described in the CHANGELOG-udb.txt file included in your Undo release archive.

Improvements in Undo Team & OEM Editions

Undo Team & OEM Editions v9.2 benefit from the UDB improvements described above.

There are no new headline features specifically for Undo Team & OEM Editions in the 9.2 release.

Further product changes relating to Undo Team & OEM Editions are described in the following changelog files included in your Undo release archive:

  • undolr/CHANGELOG.txt for changes to LiveRecorder

  • keyserver/CHANGELOG.txt for changes to the Undo Keyserver

Removals

Release 9.2 removes some legacy product features and behaviors as described below.

  • UDB can no longer load recordings that were made by UDB or LiveRecorder older than version 6.8.

  • Use of UDB with Undo Keyserver releases older than version 6.8 is no longer supported.

  • Use of the Undo Keyserver with UDB releases older than version 6.8 is no longer supported.

Life cycle

Release 9.2 is expected to:

  • receive necessary patches for a 6-month period ending at the end of August 2026;

  • produce Undo recordings that can be loaded in future versions of UDB released within the 3-year period ending at the end of February 2029.

System requirements

There are no significant changes to the Undo system requirements in the 9.2 release.

For a list of the system requirements for a given release, see the documentation at docs/userguide/html/SystemRequirements.html in the release directory. The system requirements for the latest Undo release are always provided in full at System requirements.