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Add a PTY multiplexer (/dev/ptmx) device.

Browse source 
When you open /dev/ptmx, you get a file descriptor pointing to one of the
available MasterPTY's. If none are available, you get an EBUSY.

This makes it possible to open multiple (up to 4) Terminals. :^)

To support this, I also added a CharacterDevice::open() that gets control
when VFS is opening a CharacterDevice. This is useful when we want to return
a custom FileDescriptor like we do here.
This commit is contained in:
Andreas Kling 2019-01-16 13:36:10 +01:00
parent b46ae2bf09
commit 9dd29f9aa9
13 changed files with 75 additions and 37 deletions
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27
Kernel/PTYMultiplexer.cpp Normal file
View file

@ -0,0 +1,27 @@
#include "PTYMultiplexer.h"
#include "MasterPTY.h"
#include <LibC/errno_numbers.h>
PTYMultiplexer::PTYMultiplexer()
: CharacterDevice(5, 2)
{
m_freelist.ensureCapacity(4);
for (int i = 4; i > 0; --i)
m_freelist.unchecked_append(adopt(*new MasterPTY(i - 1)));
}
PTYMultiplexer::~PTYMultiplexer()
{
}
RetainPtr<FileDescriptor> PTYMultiplexer::open(int& error, int options)
{
LOCKER(m_lock);
if (m_freelist.is_empty()) {
error = -EBUSY;
return nullptr;
}
auto master = m_freelist.takeLast();
dbgprintf("PTYMultiplexer::open: Vending master %u\n", master->index());
return VFS::the().open(move(master), error, options);
}