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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/NonnullRefPtr.h>
#include <AK/RefCounted.h>
#include <AK/String.h>
#include <AK/Types.h>
#include <AK/Weakable.h>
#include <Kernel/Forward.h>
#include <Kernel/KResult.h>
#include <Kernel/UnixTypes.h>
#include <Kernel/UserOrKernelBuffer.h>
#include <Kernel/VirtualAddress.h>
namespace Kernel {
class File;
class FileBlockCondition : public Thread::BlockCondition {
public:
FileBlockCondition() { }
virtual bool should_add_blocker(Thread::Blocker& b, void* data) override
{
VERIFY(b.blocker_type() == Thread::Blocker::Type::File);
auto& blocker = static_cast<Thread::FileBlocker&>(b);
return !blocker.unblock(true, data);
}
void unblock()
{
ScopedSpinLock lock(m_lock);
do_unblock([&](auto& b, void* data, bool&) {
VERIFY(b.blocker_type() == Thread::Blocker::Type::File);
auto& blocker = static_cast<Thread::FileBlocker&>(b);
return blocker.unblock(false, data);
});
}
};
// File is the base class for anything that can be referenced by a FileDescription.
//
// The most important functions in File are:
//
// read() and write()
// - Implement reading and writing.
// - Return the number of bytes read/written, OR a negative error code.
//
// can_read() and can_write()
//
// - Used to implement blocking I/O, and the select() and poll() syscalls.
// - Return true if read() or write() would succeed, respectively.
// - Note that can_read() should return true in EOF conditions,
// and a subsequent call to read() should return 0.
//
// ioctl()
//
// - Optional. If unimplemented, ioctl() on this File will fail with -ENOTTY.
// - Can be overridden in subclasses to implement arbitrary functionality.
// - Subclasses should take care to validate incoming addresses before dereferencing.
//
// mmap()
//
// - Optional. If unimplemented, mmap() on this File will fail with -ENODEV.
// - Called by mmap() when userspace wants to memory-map this File somewhere.
// - Should create a Region in the Process and return it if successful.
class File
: public RefCounted<File>
, public Weakable<File> {
public:
virtual ~File();
virtual KResultOr<NonnullRefPtr<FileDescription>> open(int options);
virtual KResult close();
virtual bool can_read(const FileDescription&, size_t) const = 0;
virtual bool can_write(const FileDescription&, size_t) const = 0;
virtual KResult attach(FileDescription&);
virtual void detach(FileDescription&);
virtual void did_seek(FileDescription&, off_t) { }
virtual KResultOr<size_t> read(FileDescription&, u64, UserOrKernelBuffer&, size_t) = 0;
virtual KResultOr<size_t> write(FileDescription&, u64, const UserOrKernelBuffer&, size_t) = 0;
virtual int ioctl(FileDescription&, unsigned request, FlatPtr arg);
virtual KResultOr<Region*> mmap(Process&, FileDescription&, const Range&, u64 offset, int prot, bool shared);
virtual KResult stat(::stat&) const { return EBADF; }
virtual String absolute_path(const FileDescription&) const = 0;
virtual KResult truncate(u64) { return EINVAL; }
virtual KResult chown(FileDescription&, uid_t, gid_t) { return EBADF; }
virtual KResult chmod(FileDescription&, mode_t) { return EBADF; }
virtual const char* class_name() const = 0;
virtual bool is_seekable() const { return false; }
virtual bool is_inode() const { return false; }
virtual bool is_fifo() const { return false; }
virtual bool is_device() const { return false; }
virtual bool is_tty() const { return false; }
virtual bool is_master_pty() const { return false; }
virtual bool is_block_device() const { return false; }
virtual bool is_character_device() const { return false; }
virtual bool is_socket() const { return false; }
virtual FileBlockCondition& block_condition() { return m_block_condition; }
size_t attach_count() const { return m_attach_count; }
protected:
File();
void evaluate_block_conditions()
{
if (Processor::current().in_irq()) {
// If called from an IRQ handler we need to delay evaluation
// and unblocking of waiting threads. Note that this File
// instance may be deleted until the deferred call is executed!
Processor::deferred_call_queue([self = make_weak_ptr()]() {
if (auto file = self.strong_ref())
file->do_evaluate_block_conditions();
});
} else {
do_evaluate_block_conditions();
}
}
private:
ALWAYS_INLINE void do_evaluate_block_conditions()
{
VERIFY(!Processor::current().in_irq());
block_condition().unblock();
}
FileBlockCondition m_block_condition;
size_t m_attach_count { 0 };
};
}
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