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/*
* Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/FileSystem/TmpFS.h>
#include <Kernel/Process.h>
#include <LibC/limits.h>
namespace Kernel {
ErrorOr<NonnullRefPtr<TmpFS>> TmpFS::try_create()
{
return adopt_nonnull_ref_or_enomem(new (nothrow) TmpFS);
}
TmpFS::TmpFS()
{
}
TmpFS::~TmpFS()
{
}
ErrorOr<void> TmpFS::initialize()
{
m_root_inode = TRY(TmpFSInode::try_create_root(*this));
return {};
}
Inode& TmpFS::root_inode()
{
VERIFY(!m_root_inode.is_null());
return *m_root_inode;
}
void TmpFS::register_inode(TmpFSInode& inode)
{
MutexLocker locker(m_lock);
VERIFY(inode.identifier().fsid() == fsid());
auto index = inode.identifier().index();
m_inodes.set(index, inode);
}
void TmpFS::unregister_inode(InodeIdentifier identifier)
{
MutexLocker locker(m_lock);
VERIFY(identifier.fsid() == fsid());
m_inodes.remove(identifier.index());
}
unsigned TmpFS::next_inode_index()
{
MutexLocker locker(m_lock);
return m_next_inode_index++;
}
ErrorOr<NonnullRefPtr<Inode>> TmpFS::get_inode(InodeIdentifier identifier) const
{
MutexLocker locker(m_lock, Mutex::Mode::Shared);
VERIFY(identifier.fsid() == fsid());
auto it = m_inodes.find(identifier.index());
if (it == m_inodes.end())
return ENOENT;
return it->value;
}
TmpFSInode::TmpFSInode(TmpFS& fs, const InodeMetadata& metadata, InodeIdentifier parent)
: Inode(fs, fs.next_inode_index())
, m_metadata(metadata)
, m_parent(parent)
{
m_metadata.inode = identifier();
}
TmpFSInode::~TmpFSInode()
{
}
ErrorOr<NonnullRefPtr<TmpFSInode>> TmpFSInode::try_create(TmpFS& fs, InodeMetadata const& metadata, InodeIdentifier parent)
{
auto inode = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) TmpFSInode(fs, metadata, parent)));
fs.register_inode(inode);
return inode;
}
ErrorOr<NonnullRefPtr<TmpFSInode>> TmpFSInode::try_create_root(TmpFS& fs)
{
InodeMetadata metadata;
auto now = kgettimeofday().to_truncated_seconds();
metadata.atime = now;
metadata.ctime = now;
metadata.mtime = now;
metadata.mode = S_IFDIR | S_ISVTX | 0777;
return try_create(fs, metadata, { fs.fsid(), 1 });
}
InodeMetadata TmpFSInode::metadata() const
{
MutexLocker locker(m_inode_lock, Mutex::Mode::Shared);
return m_metadata;
}
ErrorOr<void> TmpFSInode::traverse_as_directory(Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)> callback) const
{
MutexLocker locker(m_inode_lock, Mutex::Mode::Shared);
if (!is_directory())
return ENOTDIR;
TRY(callback({ ".", identifier(), 0 }));
TRY(callback({ "..", m_parent, 0 }));
for (auto& child : m_children) {
TRY(callback({ child.name->view(), child.inode->identifier(), 0 }));
}
return {};
}
ErrorOr<size_t> TmpFSInode::read_bytes(off_t offset, size_t size, UserOrKernelBuffer& buffer, OpenFileDescription*) const
{
MutexLocker locker(m_inode_lock, Mutex::Mode::Shared);
VERIFY(!is_directory());
VERIFY(offset >= 0);
if (!m_content)
return 0;
if (offset >= m_metadata.size)
return 0;
if (static_cast<off_t>(size) > m_metadata.size - offset)
size = m_metadata.size - offset;
TRY(buffer.write(m_content->data() + offset, size));
return size;
}
ErrorOr<size_t> TmpFSInode::write_bytes(off_t offset, size_t size, const UserOrKernelBuffer& buffer, OpenFileDescription*)
{
MutexLocker locker(m_inode_lock);
VERIFY(!is_directory());
VERIFY(offset >= 0);
TRY(prepare_to_write_data());
off_t old_size = m_metadata.size;
off_t new_size = m_metadata.size;
if (static_cast<off_t>(offset + size) > new_size)
new_size = offset + size;
if (static_cast<u64>(new_size) > (NumericLimits<size_t>::max() / 2)) // on 32-bit, size_t might be 32 bits while off_t is 64 bits
return ENOMEM; // we won't be able to resize to this capacity
if (new_size > old_size) {
if (m_content && static_cast<off_t>(m_content->capacity()) >= new_size) {
m_content->set_size(new_size);
} else {
// Grow the content buffer 2x the new sizeto accommodate repeating write() calls.
// Note that we're not actually committing physical memory to the buffer
// until it's needed. We only grow VM here.
// FIXME: Fix this so that no memcpy() is necessary, and we can just grow the
// KBuffer and it will add physical pages as needed while keeping the
// existing ones.
auto tmp = TRY(KBuffer::try_create_with_size(new_size * 2));
tmp->set_size(new_size);
if (m_content)
memcpy(tmp->data(), m_content->data(), old_size);
m_content = move(tmp);
}
m_metadata.size = new_size;
notify_watchers();
}
TRY(buffer.read(m_content->data() + offset, size)); // TODO: partial reads?
did_modify_contents();
return size;
}
ErrorOr<NonnullRefPtr<Inode>> TmpFSInode::lookup(StringView name)
{
MutexLocker locker(m_inode_lock, Mutex::Mode::Shared);
VERIFY(is_directory());
if (name == ".")
return *this;
if (name == "..")
return fs().get_inode(m_parent);
auto* child = find_child_by_name(name);
if (!child)
return ENOENT;
return child->inode;
}
TmpFSInode::Child* TmpFSInode::find_child_by_name(StringView name)
{
for (auto& child : m_children) {
if (child.name->view() == name)
return &child;
}
return nullptr;
}
void TmpFSInode::notify_watchers()
{
set_metadata_dirty(true);
set_metadata_dirty(false);
}
ErrorOr<void> TmpFSInode::flush_metadata()
{
// We don't really have any metadata that could become dirty.
// The only reason we even call set_metadata_dirty() is
// to let the watchers know we have updates. Once that is
// switched to a different mechanism, we can stop ever marking
// our metadata as dirty at all.
set_metadata_dirty(false);
return {};
}
ErrorOr<void> TmpFSInode::chmod(mode_t mode)
{
MutexLocker locker(m_inode_lock);
m_metadata.mode = mode;
notify_watchers();
return {};
}
ErrorOr<void> TmpFSInode::chown(UserID uid, GroupID gid)
{
MutexLocker locker(m_inode_lock);
m_metadata.uid = uid;
m_metadata.gid = gid;
notify_watchers();
return {};
}
ErrorOr<NonnullRefPtr<Inode>> TmpFSInode::create_child(StringView name, mode_t mode, dev_t dev, UserID uid, GroupID gid)
{
MutexLocker locker(m_inode_lock);
// TODO: Support creating devices on TmpFS.
if (dev != 0)
return ENOTSUP;
time_t now = kgettimeofday().to_truncated_seconds();
InodeMetadata metadata;
metadata.mode = mode;
metadata.uid = uid;
metadata.gid = gid;
metadata.atime = now;
metadata.ctime = now;
metadata.mtime = now;
auto child = TRY(TmpFSInode::try_create(fs(), metadata, identifier()));
TRY(add_child(*child, name, mode));
return child;
}
ErrorOr<void> TmpFSInode::add_child(Inode& child, StringView name, mode_t)
{
VERIFY(is_directory());
VERIFY(child.fsid() == fsid());
if (name.length() > NAME_MAX)
return ENAMETOOLONG;
auto name_kstring = TRY(KString::try_create(name));
// Balanced by `delete` in remove_child()
auto* child_entry = new (nothrow) Child { move(name_kstring), static_cast<TmpFSInode&>(child) };
if (!child_entry)
return ENOMEM;
MutexLocker locker(m_inode_lock);
m_children.append(*child_entry);
did_add_child(child.identifier(), name);
return {};
}
ErrorOr<void> TmpFSInode::remove_child(StringView name)
{
MutexLocker locker(m_inode_lock);
VERIFY(is_directory());
if (name == "." || name == "..")
return {};
auto* child = find_child_by_name(name);
if (!child)
return ENOENT;
auto child_id = child->inode->identifier();
child->inode->did_delete_self();
m_children.remove(*child);
did_remove_child(child_id, name);
// Balanced by `new` in add_child()
delete child;
return {};
}
ErrorOr<void> TmpFSInode::truncate(u64 size)
{
MutexLocker locker(m_inode_lock);
VERIFY(!is_directory());
if (size == 0)
m_content.clear();
else if (!m_content) {
m_content = TRY(KBuffer::try_create_with_size(size));
} else if (static_cast<size_t>(size) < m_content->capacity()) {
size_t prev_size = m_metadata.size;
m_content->set_size(size);
if (prev_size < static_cast<size_t>(size))
memset(m_content->data() + prev_size, 0, size - prev_size);
} else {
size_t prev_size = m_metadata.size;
auto tmp = TRY(KBuffer::try_create_with_size(size));
memcpy(tmp->data(), m_content->data(), prev_size);
m_content = move(tmp);
}
m_metadata.size = size;
notify_watchers();
return {};
}
ErrorOr<void> TmpFSInode::set_atime(time_t time)
{
MutexLocker locker(m_inode_lock);
m_metadata.atime = time;
notify_watchers();
return {};
}
ErrorOr<void> TmpFSInode::set_ctime(time_t time)
{
MutexLocker locker(m_inode_lock);
m_metadata.ctime = time;
notify_watchers();
return {};
}
ErrorOr<void> TmpFSInode::set_mtime(time_t t)
{
MutexLocker locker(m_inode_lock);
m_metadata.mtime = t;
notify_watchers();
return {};
}
void TmpFSInode::one_ref_left()
{
// Destroy ourselves.
fs().unregister_inode(identifier());
}
}
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