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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.
58 lines
1.6 KiB
C++
58 lines
1.6 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/Debug.h>
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#include <Kernel/FileSystem/FileDescription.h>
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#include <Kernel/Process.h>
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namespace Kernel {
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KResultOr<FlatPtr> Process::sys$fcntl(int fd, int cmd, u32 arg)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
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REQUIRE_PROMISE(stdio);
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dbgln_if(IO_DEBUG, "sys$fcntl: fd={}, cmd={}, arg={}", fd, cmd, arg);
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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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// NOTE: The FD flags are not shared between FileDescription objects.
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// This means that dup() doesn't copy the FD_CLOEXEC flag!
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switch (cmd) {
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case F_DUPFD: {
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int arg_fd = (int)arg;
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if (arg_fd < 0)
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return EINVAL;
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auto new_fd_or_error = fds().allocate(arg_fd);
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if (new_fd_or_error.is_error())
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return new_fd_or_error.error();
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auto new_fd = new_fd_or_error.release_value();
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m_fds[new_fd.fd].set(*description);
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return new_fd.fd;
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}
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case F_GETFD:
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return m_fds[fd].flags();
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case F_SETFD:
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m_fds[fd].set_flags(arg);
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break;
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case F_GETFL:
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return description->file_flags();
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case F_SETFL:
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description->set_file_flags(arg);
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break;
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case F_ISTTY:
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return description->is_tty();
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case F_GETLK:
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return description->get_flock(Userspace<flock*>(arg));
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case F_SETLK:
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return description->apply_flock(*Process::current(), Userspace<const flock*>(arg));
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default:
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return EINVAL;
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}
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return 0;
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}
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}
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