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Kernel: Get RefPtr<Device> from the DeviceManagement::get_device method

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Instead of returning a raw pointer, which could be technically invalid
when using it in the caller function, we return a valid RefPtr of such
device.

This ensures that the code in DevPtsFS is now safe from a rare race
condition in which the SlavePTY device is gone but we still have a
pointer to it.
This commit is contained in:
Liav A 2024-03-04 21:19:31 +02:00 • committed by Andrew Kaster
parent 5dcf03ad9a
commit 11ead5c84f
6 changed files with 24 additions and 16 deletions
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10
Kernel/FileSystem/DevPtsFS/FileSystem.cpp
View file

@ -23,7 +23,7 @@ DevPtsFS::~DevPtsFS() = default;
ErrorOr<void> DevPtsFS::initialize()
{
m_root_inode = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) DevPtsFSInode(*this, 1, nullptr)));
m_root_inode = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) DevPtsFSInode(*this)));
m_root_inode->m_metadata.inode = { fsid(), 1 };
m_root_inode->m_metadata.mode = 0040555;
m_root_inode->m_metadata.uid = 0;
@ -55,15 +55,15 @@ ErrorOr<NonnullRefPtr<Inode>> DevPtsFS::get_inode(InodeIdentifier inode_id) cons
return *m_root_inode;
unsigned pty_index = inode_index_to_pty_index(inode_id.index());
auto* device = DeviceManagement::the().get_device(201, pty_index);
auto device = DeviceManagement::the().get_device(201, pty_index);
VERIFY(device);
auto* pts_device = static_cast<SlavePTY*>(device);
auto& pts_device = static_cast<SlavePTY&>(*device);
auto inode = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) DevPtsFSInode(const_cast<DevPtsFS&>(*this), inode_id.index(), pts_device)));
inode->m_metadata.inode = inode_id;
inode->m_metadata.size = 0;
inode->m_metadata.uid = pts_device->uid();
inode->m_metadata.gid = pts_device->gid();
inode->m_metadata.uid = pts_device.uid();
inode->m_metadata.gid = pts_device.gid();
inode->m_metadata.mode = 0020600;
inode->m_metadata.major_device = device->major();
inode->m_metadata.minor_device = device->minor();

13
Kernel/FileSystem/DevPtsFS/Inode.cpp
View file

@ -16,11 +16,16 @@ static InodeIndex pty_index_to_inode_index(unsigned pty_index)
return pty_index + 2;
}
DevPtsFSInode::DevPtsFSInode(DevPtsFS& fs, InodeIndex index, SlavePTY* pty)
: Inode(fs, index)
// NOTE: This constructor is used for the root inode only.
DevPtsFSInode::DevPtsFSInode(DevPtsFS& fs)
: Inode(fs, 1)
{
}
DevPtsFSInode::DevPtsFSInode(DevPtsFS& fs, InodeIndex index, SlavePTY& pty)
: Inode(fs, index)
, m_pty(pty)
{
if (pty)
m_pty = *pty;
}
DevPtsFSInode::~DevPtsFSInode() = default;

5
Kernel/FileSystem/DevPtsFS/Inode.h
View file

@ -23,7 +23,10 @@ public:
DevPtsFS const& fs() const { return static_cast<DevPtsFS const&>(Inode::fs()); }
private:
DevPtsFSInode(DevPtsFS&, InodeIndex, SlavePTY*);
DevPtsFSInode(DevPtsFS&, InodeIndex, SlavePTY&);
// NOTE: This constructor is used for the root inode only.
DevPtsFSInode(DevPtsFS&);
// ^Inode
virtual ErrorOr<size_t> read_bytes_locked(off_t, size_t, UserOrKernelBuffer& buffer, OpenFileDescription*) const override;