# Major changes between releases

## 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](https://jmmv.dev/2020/01/osxfuse-hardlinks-dladdr.html) 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.