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NEWS.md

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Major changes between releases

Changes in version X.Y.Z

STILL UNDER DEVELOPMENT; NOT RELEASED YET.

  • Issue #111: Optimized map operations, cutting down their CPU time by about 15%.

Changes in version 0.2.0

Released on 2020-04-20.

  • The reconfiguration protocol has completely changed in order to support more efficient reconfigurations. If you are using sandboxfs with Bazel, you will need to upgrade to Bazel 3.0.0 to use this version. See below for more details on how the protocol has changed.

  • Made sandboxfs process reconfiguration requests in parallel, which has a significant performance impact when those requests are large.

  • Fixed a bug where writes on a file descriptor that had been duplicated and closed did not update the file size, resulting in bad data being returned on future reads.

  • Fixed timestamp updates so that the birthtime rolls back to an older mtime to mimic BSD semantics.

  • Fixed hardlink counts so that they are zero for handles that point to deleted files or directories.

  • Added support for extended attributes. Must be explicitly enabled by passing the --xattrs option.

  • Added support to change the timestamps of a symlink on systems that have this feature.

  • Disabled the path-based node cache by default and added a --node_cache flag to reenable it. This fixes crashes when running Java within a sandboxfs instance where the Java toolchain is mapped under multiple locations and the first mapped location vanishes. See The OSXFUSE, hard links, and dladdr puzzle for details.

The following are the highlights of the changes to the reconfiguration protocol in this release. You can read the full specification in the sandboxfs(1) manual page:

  • Use JSON streams for both the requests and the responses, instead of the previous ad-hoc line-oriented protocol.

  • Each map and unmap request carries a list of mappings to map and unmap, respectively, along with the "root" path where all those mappings start. This is to allow sandboxfs to process the requests more efficiently.

  • Each request contains a tag, which is then propagated to the response for that request. This is to allow sandboxfs to process requests in parallel.

  • Work at the level of sandboxes, not paths, where a sandbox is defined as a top-level directory with a collection of mappings beneath it.

    This essentially makes reconfigurations less powerful than they were, but also makes them infinitely simpler to understand and manage. Furthermore, this lines up better with the needs of Bazel, our primary customer, and with sandboxfs' own name.

  • Take prefix-encoded paths to minimize the size of the reconfiguration requests. This has shown to significantly reduce the CPU consumption of both sandboxfs and Bazel during a build, as the size of the reconfiguration messages is drastically smaller.

  • Accept short aliases for all fields, thus further minimizing the size of reconfiguration requests, and also to accept omitting optional fields.

Changes in version 0.1.1

Released on 2019-10-24.

  • Fixed the definition of --input and --output to require an argument, which makes --foo bar and --foo=bar equivalent. This can be thought to break backwards compatibility but, in reality, it does not. The previous behavior was just broken: specifying --foo bar would cause bar to be treated as an argument and --foo to use its default value, which meant that these two flags would be ignored when supplied under this syntax.

  • Fixed --input and --output to handle stdin and stdout correctly when running e.g. under sudo.

  • Make create operations honor the UID and GID of the caller user instead of inheriting the permissions of whoever was running sandboxfs. Only has an effect when using --allow=other or --allow=root.

Changes in version 0.1.0

Released on 2019-02-05.

This is the first formal release of the sandboxfs project.

WARNING: The interaction points with sandboxfs are subject to change at this point. In particular, the command-line interface and the data format used to reconfigure sandboxfs while it's running will most certainly change.