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serenity/Kernel/FileSystem/AnonymousFile.cpp

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Kernel: Add anonymous files, created with sys$anon_create() This patch adds a new AnonymousFile class which is a File backed by an AnonymousVMObject that can only be mmap'ed and nothing else, really. I'm hoping that this can become a replacement for shbufs. :^)
2021-01-15 11:28:07 +01:00
/*
Kernel: Simplify the File memory-mapping API Before this change, we had File::mmap() which did all the work of setting up a VMObject, and then creating a Region in the current process's address space. This patch simplifies the interface by removing the region part. Files now only have to return a suitable VMObject from vmobject_for_mmap(), and then sys$mmap() itself will take care of actually mapping it into the address space. This fixes an issue where we'd try to block on I/O (for inode metadata lookup) while holding the address space spinlock. It also reduces time spent holding the address space lock.
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* Copyright (c) 2021-2022, Andreas Kling <kling@serenityos.org>
Kernel: Add anonymous files, created with sys$anon_create() This patch adds a new AnonymousFile class which is a File backed by an AnonymousVMObject that can only be mmap'ed and nothing else, really. I'm hoping that this can become a replacement for shbufs. :^)
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*
Everything: Move to SPDX license identifiers in all files. SPDX License Identifiers are a more compact / standardized way of representing file license information. See: https://spdx.dev/resources/use/#identifiers This was done with the `ambr` search and replace tool. ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
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* SPDX-License-Identifier: BSD-2-Clause
Kernel: Add anonymous files, created with sys$anon_create() This patch adds a new AnonymousFile class which is a File backed by an AnonymousVMObject that can only be mmap'ed and nothing else, really. I'm hoping that this can become a replacement for shbufs. :^)
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*/
#include <Kernel/FileSystem/AnonymousFile.h>
Kernel: Rename Kernel/VM/ to Kernel/Memory/ This directory isn't just about virtual memory, it's about all kinds of memory management.
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#include <Kernel/Memory/AnonymousVMObject.h>
Kernel: Add anonymous files, created with sys$anon_create() This patch adds a new AnonymousFile class which is a File backed by an AnonymousVMObject that can only be mmap'ed and nothing else, really. I'm hoping that this can become a replacement for shbufs. :^)
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#include <Kernel/Process.h>
namespace Kernel {
Kernel: Make self-contained locking smart pointers their own classes Until now, our kernel has reimplemented a number of AK classes to provide automatic internal locking: - RefPtr - NonnullRefPtr - WeakPtr - Weakable This patch renames the Kernel classes so that they can coexist with the original AK classes: - RefPtr => LockRefPtr - NonnullRefPtr => NonnullLockRefPtr - WeakPtr => LockWeakPtr - Weakable => LockWeakable The goal here is to eventually get rid of the Lock* classes in favor of using external locking.
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AnonymousFile::AnonymousFile(NonnullLockRefPtr<Memory::AnonymousVMObject> vmobject)
Kernel: Add anonymous files, created with sys$anon_create() This patch adds a new AnonymousFile class which is a File backed by an AnonymousVMObject that can only be mmap'ed and nothing else, really. I'm hoping that this can become a replacement for shbufs. :^)
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: m_vmobject(move(vmobject))
{
}
Kernel: Use default constructors/destructors https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#cother-other-default-operation-rules "The compiler is more likely to get the default semantics right and you cannot implement these functions better than the compiler."
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AnonymousFile::~AnonymousFile() = default;
Kernel: Add anonymous files, created with sys$anon_create() This patch adds a new AnonymousFile class which is a File backed by an AnonymousVMObject that can only be mmap'ed and nothing else, really. I'm hoping that this can become a replacement for shbufs. :^)
2021-01-15 11:28:07 +01:00
Kernel: Simplify the File memory-mapping API Before this change, we had File::mmap() which did all the work of setting up a VMObject, and then creating a Region in the current process's address space. This patch simplifies the interface by removing the region part. Files now only have to return a suitable VMObject from vmobject_for_mmap(), and then sys$mmap() itself will take care of actually mapping it into the address space. This fixes an issue where we'd try to block on I/O (for inode metadata lookup) while holding the address space spinlock. It also reduces time spent holding the address space lock.
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ErrorOr<NonnullLockRefPtr<Memory::VMObject>> AnonymousFile::vmobject_for_mmap(Process&, Memory::VirtualRange const&, u64& offset, bool)
Kernel: Add anonymous files, created with sys$anon_create() This patch adds a new AnonymousFile class which is a File backed by an AnonymousVMObject that can only be mmap'ed and nothing else, really. I'm hoping that this can become a replacement for shbufs. :^)
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{
if (offset != 0)
Kernel+LibC: Turn errno codes into a strongly typed enum ..and allow implicit creation of KResult and KResultOr from ErrnoCode. This means that kernel functions that return those types can finally do "return EINVAL;" and it will just work. There's a handful of functions that still deal with signed integers that should be converted to return KResults.
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return EINVAL;
Kernel: Add anonymous files, created with sys$anon_create() This patch adds a new AnonymousFile class which is a File backed by an AnonymousVMObject that can only be mmap'ed and nothing else, really. I'm hoping that this can become a replacement for shbufs. :^)
2021-01-15 11:28:07 +01:00
Kernel: Simplify the File memory-mapping API Before this change, we had File::mmap() which did all the work of setting up a VMObject, and then creating a Region in the current process's address space. This patch simplifies the interface by removing the region part. Files now only have to return a suitable VMObject from vmobject_for_mmap(), and then sys$mmap() itself will take care of actually mapping it into the address space. This fixes an issue where we'd try to block on I/O (for inode metadata lookup) while holding the address space spinlock. It also reduces time spent holding the address space lock.
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return m_vmobject;
Kernel: Add anonymous files, created with sys$anon_create() This patch adds a new AnonymousFile class which is a File backed by an AnonymousVMObject that can only be mmap'ed and nothing else, really. I'm hoping that this can become a replacement for shbufs. :^)
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}
Everywhere: Run clang-format
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ErrorOr<NonnullOwnPtr<KString>> AnonymousFile::pseudo_path(OpenFileDescription const&) const
Kernel: Clarify ambiguous {File,Description}::absolute_path Found due to smelly code in InodeFile::absolute_path. In particular, this replaces the following misleading methods: File::absolute_path This method *never* returns an actual path, and if called on an InodeFile (which is impossible), it would VERIFY_NOT_REACHED(). OpenFileDescription::try_serialize_absolute_path OpenFileDescription::absolute_path These methods do not guarantee to return an actual path (just like the other method), and just like Custody::absolute_path they do not guarantee accuracy. In particular, just renaming the method made a TOCTOU bug obvious. The new method signatures use KResultOr, just like try_serialize_absolute_path() already did.
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{
return KString::try_create(":anonymous-file:"sv);
}
Kernel: Add anonymous files, created with sys$anon_create() This patch adds a new AnonymousFile class which is a File backed by an AnonymousVMObject that can only be mmap'ed and nothing else, really. I'm hoping that this can become a replacement for shbufs. :^)
2021-01-15 11:28:07 +01:00
}
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