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Kyle Ambroff-Kao e1b7c1c7ac storage/SymLink: Fix Be API regression in ReadLink
After this patch, "UnitTester BSymLink" passes.

BSymLink::ReadLink() in BeOS would always return the length of the
link unless an error occurred. Before this patch, Haiku instead seemed
to emulate posix readlink() behavior, returning the number of bytes
copied into the output buffer.

BeOS also did not guarantee that the string written into the output
buffer is NULL terminated if the output buffer cannot contain the
entire link contents, but the Haiku implementation does since it is is
a basic safety issue.

This patch fixes this and updates the Haiku API docs to describe the
behavior explicitly.

Fixing this required changing behavior in bfs_read_link, which
required changes in many more places.

docs/user/storage/SymLink.dox:
src/kits/storage/SymLink.cpp:
* Don't return B_BUFFER_OVERFLOW if the provided buffer is not large
  enough to hold the link contents.
* Update documentation to clearly describe behavior.

src/add-ons/kernel/file_systems/bfs/kernel_interface.cpp:
* Change bfs_read_link() to always return the link length. This is
  called by common_read_link in the VFS, which is called by
  _kern_read_link().

src/add-ons/kernel/file_systems/btrfs/kernel_interface.cpp:
src/add-ons/kernel/file_systems/exfat/kernel_interface.cpp:
src/add-ons/kernel/file_systems/ext2/kernel_interface.cpp:
src/add-ons/kernel/file_systems/iso9660/kernel_interface.cpp:
src/add-ons/kernel/file_systems/netfs/client/netfs.cpp:
src/add-ons/kernel/file_systems/nfs/nfs_add_on.c:
src/add-ons/kernel/file_systems/ramfs/kernel_interface.cpp:
src/add-ons/kernel/file_systems/reiserfs/Iterators.cpp:
src/add-ons/kernel/file_systems/reiserfs/Iterators.h:
src/add-ons/kernel/file_systems/reiserfs/Volume.cpp:
src/add-ons/kernel/file_systems/reiserfs/Volume.h:
* Update the implementation of read_link for these filesystems. Some
  of them were incorrect, and some had just copied the posix behavior of
  bfs from before this patch.
* Use user_memcpy in ext2_read_link()
* Use user_memcpy in nfs fs_read_link()
* Use user_memcpy in reiserfs StreamReader::_ReadIndirectItem and
  StreamReader::_ReadDirectItem
* Remove unused method Volume::ReadObject in reiserfs.

src/add-ons/kernel/file_systems/packagefs/nodes/UnpackingLeafNode.cpp:
src/add-ons/kernel/file_systems/packagefs/package_links/PackageLinkSymlink.cpp:
* Update UnpackingLeafNode::ReadSymlink and
  PackageSymLink::ReadSymLink() to set the bufferSize out parameter to
  the symlink length. Both of these are called by
  packagefs_read_symlink.
* Use user_memcpy

src/add-ons/kernel/file_systems/netfs/client/netfs.cpp:
* netfs seems mostly unimplemented. Added a FIXME note for future
  implementers so that they know to implement the correct behavior.

src/system/libroot/posix/unistd/link.c:
* readlinkat() was just wrapping _kern_read_link() because before this
  patch it had expected posix behavior. But now it does not, so we
  need to return the number of bytes written to the output
  buffer.

src/build/libroot/fs.cpp:
* Update _kern_read_link() in the compatibility code to emulate the
  Haiku behavior on the host system. This is done by using an
  intermediate buffer that is guaranteed to fit the link contents and
  returning its length. The intermediate buffer is copied into the
  output buffer until there is no more room.

src/tests/kits/storage/SymLinkTest.cpp:
* This patch also resolves some test failures similar to those
  resolved in ee8cf35f0 which fixed tests for BNode. The tests were
  failing because Haiku's error checking is just better.

  BeOS allowed constructing a BSymLink with BSymLink(BDirectory*,
  const char*) with the entry name of "". The same is true of the
  equivilant SetTo() method. The BSymLink object will appear valid
  until you attempt to use it by, for example, calling the ReadLink
  method, which will return B_BAD_VALUE.

  Haiku does a more appropriate thing and returns B_ENTRY_NOT_FOUND,
  for this constructor and the equivilant SetTo(BDirectory*, const
  char*) method. This patch fixes these test assertions to match Haiku
  behavior.

docs/develop/file_systems/overview.txt:
* Add notes for future filesystem driver implementers to call this
  mistake when implementing fs_vnode_ops::read_symlink.

docs/user/drivers/fs_interface.dox:
* Fix documentation for fs_vnode_ops::read_symlink

Change-Id: I8bcb8b2a0c9333059c84ace15844c32d4efeed9d
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2502
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
Reviewed-by: Axel Dörfler <axeld@pinc-software.de>
2020-04-30 10:13:41 +00:00
3rdparty
build
data Fix URL in install-wifi-firmwares.sh 2020-04-28 17:44:57 +02:00
docs storage/SymLink: Fix Be API regression in ReadLink 2020-04-30 10:13:41 +00:00
headers smbios: add module to match SMBios vendor and product 2020-04-27 07:38:40 +00:00
src storage/SymLink: Fix Be API regression in ReadLink 2020-04-30 10:13:41 +00:00
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ReadMe.md

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.

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