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serenity/VirtualFileSystem/NullDevice.cpp
Andreas Kling c6f2890d8e Implement a basic way for read() to block.
FileHandle gets a hasDataAvailableForRead() getter.
If this returns true in sys$read(), the task will block(BlockedRead) + yield.
The fd blocked on is stored in Task::m_fdBlockedOnRead.
The scheduler then looks at the state of that fd during the unblock phase.

This makes "sh" restful. :^)

There's still some problem with the kernel not surviving the colonel task
getting scheduled. I need to figure that out and fix it.
2018-10-25 13:09:56 +02:00

29 lines
458 B
C++

#include "NullDevice.h"
#include "Limits.h"
#include <AK/StdLib.h>
#include <AK/kstdio.h>
NullDevice::NullDevice()
{
}
NullDevice::~NullDevice()
{
}
bool NullDevice::hasDataAvailableForRead() const
{
return true;
}
Unix::ssize_t NullDevice::read(byte*, Unix::size_t)
{
kprintf("NullDevice: read from null\n");
return 0;
}
Unix::ssize_t NullDevice::write(const byte*, Unix::size_t bufferSize)
{
return min(GoodBufferSize, bufferSize);
}