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4b2651ddab
The way the Process::FileDescriptions::allocate() API works today means that two callers who allocate back to back without associating a FileDescription with the allocated FD, will receive the same FD and thus one will stomp over the other. Naively tracking which FileDescriptions are allocated and moving onto the next would introduce other bugs however, as now if you "allocate" a fd and then return early further down the control flow of the syscall you would leak that fd. This change modifies this behavior by tracking which descriptions are allocated and then having an RAII type to "deallocate" the fd if the association is not setup the end of it's scope.
97 lines
3.1 KiB
C++
97 lines
3.1 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2021, sin-ack <sin-ack@protonmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/API/InodeWatcherFlags.h>
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#include <Kernel/FileSystem/Custody.h>
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#include <Kernel/FileSystem/FileDescription.h>
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#include <Kernel/FileSystem/InodeWatcher.h>
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#include <Kernel/Process.h>
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namespace Kernel {
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KResultOr<FlatPtr> Process::sys$create_inode_watcher(u32 flags)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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REQUIRE_PROMISE(rpath);
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auto fd_or_error = m_fds.allocate();
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if (fd_or_error.is_error())
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return fd_or_error.error();
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auto inode_watcher_fd = fd_or_error.release_value();
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auto watcher_or_error = InodeWatcher::create();
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if (watcher_or_error.is_error())
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return watcher_or_error.error();
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auto description_or_error = FileDescription::create(*watcher_or_error.value());
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if (description_or_error.is_error())
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return description_or_error.error();
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m_fds[inode_watcher_fd.fd].set(description_or_error.release_value());
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m_fds[inode_watcher_fd.fd].description()->set_readable(true);
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if (flags & static_cast<unsigned>(InodeWatcherFlags::Nonblock))
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m_fds[inode_watcher_fd.fd].description()->set_blocking(false);
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if (flags & static_cast<unsigned>(InodeWatcherFlags::CloseOnExec))
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m_fds[inode_watcher_fd.fd].set_flags(m_fds[inode_watcher_fd.fd].flags() | FD_CLOEXEC);
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return inode_watcher_fd.fd;
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}
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KResultOr<FlatPtr> Process::sys$inode_watcher_add_watch(Userspace<const Syscall::SC_inode_watcher_add_watch_params*> user_params)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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REQUIRE_PROMISE(rpath);
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Syscall::SC_inode_watcher_add_watch_params params;
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if (!copy_from_user(¶ms, user_params))
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return EFAULT;
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auto description = fds().file_description(params.fd);
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if (!description)
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return EBADF;
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if (!description->is_inode_watcher())
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return EBADF;
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auto inode_watcher = description->inode_watcher();
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auto path = get_syscall_path_argument(params.user_path.characters, params.user_path.length);
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if (path.is_error())
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return path.error();
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auto custody_or_error = VirtualFileSystem::the().resolve_path(path.value()->view(), current_directory());
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if (custody_or_error.is_error())
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return custody_or_error.error();
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auto& custody = custody_or_error.value();
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if (!custody->inode().fs().supports_watchers())
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return ENOTSUP;
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auto wd_or_error = inode_watcher->register_inode(custody->inode(), params.event_mask);
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if (wd_or_error.is_error())
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return wd_or_error.error();
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return wd_or_error.value();
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}
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KResultOr<FlatPtr> Process::sys$inode_watcher_remove_watch(int fd, int wd)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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auto description = fds().file_description(fd);
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if (!description)
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return EBADF;
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if (!description->is_inode_watcher())
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return EBADF;
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auto inode_watcher = description->inode_watcher();
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auto result = inode_watcher->unregister_by_wd(wd);
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if (result.is_error())
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return result;
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return 0;
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}
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}
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