Jim906 7020e10ab8 userlandfs: Fix file_cache_read
* Prevent the userlandfs server from calling clone_area on an area
  that might have already been deleted.
* _HandleRequest(FileCacheReadRequest*) waits for a reply from the
  server when bytesRead > 0.  This ensures that the server has time to
  use the area holding the returned data, before that area is deleted
  when the RequestAllocator goes out of scope in the kernel add-on.
  However, if bytesRead is 0, the server will still call clone_area,
  even though by that time the area has probably been deleted.  This
  leads to a B_BAD_VALUE error when the FS tries to use the emulated
  file_cache_read at the end of a file, which differs from the
  normal behavior of file_cache_read.
* _HandleRequest(ReadFromIORequestRequest*) has similar logic in that
  it waits for a server reply, but not if size == 0.  It's possible
  that a similar problem could occur here. This test can be
  dropped if no requests with size 0 are ever sent from the server to
  begin with.
* For other _HandleRequest overrides, the kernel never waits for a
  server reply, and this causes no problems.  This could be because the
  size of data returned fits in the port buffer, so no external area
  needs to be created by RequestAllocator::AllocateAddress.

Change-Id: If070901c25d446e00e67a74a7883808d8a38dae2
Reviewed-on: https://review.haiku-os.org/c/haiku/+/8721
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
2024-12-30 17:00:48 +00:00
2024-12-28 08:08:56 +00:00
2024-12-22 08:40:35 +00:00
2024-12-30 17:00:48 +00:00
2018-01-04 00:04:02 -06:00
2021-06-13 21:06:58 +00:00

Haiku

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Haiku is an open-source operating system that specifically targets personal computing. Inspired by the BeOS, Haiku is fast, simple to use, easy to learn and yet very powerful.

Goals

  • Sensible defaults with minimal configuration required.
  • Clean, clear, concise code.
  • Unified desktop environment.

Trying Haiku

Haiku provides pre-built nightly images and release images. Haiku is compatible with a large variety of hardware, but in case you don't want to "take the plunge" and install Haiku on bare metal, you can install it on a virtual machine (VM) instead. If you've never used a VM before, you can follow one of the "Emulating Haiku" guides.

Compiling Haiku

See ReadMe.Compiling.

Contributing

Haiku is a meritocratic open source project with a large variety of tasks. Even if you can't write code, you can still help! Haiku needs designers, (technical) writers, translators, testers... Get involved and help out!

Contributing code

If you're submitting a patch to us, please make sure you're following the patch submitting guidelines.

If you're having trouble finding something in the source tree, you can use one of our web-based source code browsers:

Contributing documentation

The main piece of documentation that still needs work are the API docs (found in the tree at docs/user). Just find an undocumented class, write documentation for it, and submit a patch.

Contributing translations

See wiki:i18n.

Contributing software ports

See HaikuPorts.

Contributing to our infrastructure

See Infrastructure.

Description
The Haiku operating system
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