Norman Feske 7ac32ea60c libc: support for ioctls via ioctl directory
This patch introduces a new scheme of handling ioctl operations that
maps ioctls to pseudo-file accesses, similar to how the libc maps socket
calls to socket-fs operations.

A device file can be accompanied with a (hidden) directory that is named
after the device file and hosts pseudo files for triggering the various
device operations. For example, for accessing a terminal, the directory
structure looks like this:

  /dev/terminal
  /dev/.terminal/info

The 'info' file contains device information in XML format. The type of
the XML node corresponds to the device type. E.g., If the libc receives
a 'TIOCGWINSZ' ioctl for /dev/terminal, it reads the content of
/dev/.terminal/info to obtain the terminal-size information. In this
case, the 'info' file looks as follows:

  <terminal rows="25" columns="80/>

Following this scheme, VFS plugins can support ioctl operations by
providing an ioctl directory in addition to the actual device file.

Internally, the mechanism uses the 'os/vfs.h' API to access pseudo
files. Hence, we need to propagate the Vfs::Env to 'vfs_plugin.cc' to
create an instance of a 'Directory' for the root for the VFS.

Issue #3519
2019-11-19 14:39:09 +01:00
..
2019-11-19 14:23:54 +01:00
2016-08-30 17:24:00 +02:00

This directory contains ports of popular 3rd-party software to Genode.


Usage
-----

The tool './tool/ports/prepare_port' in the toplevel directory automates the
task of downloading and preparing the library source codes. You can select
individual packages that have to be prepared by specifying their base names
(without the version number) as command-line argument. For example, the
following command prepares both the C library and the Freetype library:
! ./tool/ports/prepare_port libc freetype

To compile and link against 3rd-party libraries of the 'libports' repository,
you have to include the repository into the build process by appending it to the
'REPOSITORIES' declaration of your '<build-dir>/etc/build.conf' file.


Under the hood
--------------

For each library, there is a file contained in the 'libports/ports/'
subdirectory. The file is named after the library and contains the
library-specific rules for downloading the source code and installing header
files.


How does 'libports' relate to the other repositories?
-----------------------------------------------------

Most libraries hosted in the 'libports' repository expect a complete C library,
which is provided with the 'libc' package. Please do not forget to prepare the
libc package when using any of the other libports packages. The libc, in turn,
depends on the 'os' repository for its back end. Because the 'os' repository is
the home of the dynamic linker, libraries contained in 'libports' are safe to
assume the presence of the dynamic linker and, thus, should be built as shared
libraries.