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f99af1bef0
It's not safe to store OpenFileDescription in a raw pointer when blocking, since another thread may decide to close the corresponding file descriptor.
110 lines
3.5 KiB
C++
110 lines
3.5 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/OpenFileDescription.h>
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#include <Kernel/Process.h>
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namespace Kernel {
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using BlockFlags = Thread::FileBlocker::BlockFlags;
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static ErrorOr<NonnullRefPtr<OpenFileDescription>> open_readable_file_description(Process::OpenFileDescriptions const& fds, int fd)
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{
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auto description = TRY(fds.open_file_description(fd));
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if (!description->is_readable())
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return EBADF;
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if (description->is_directory())
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return EISDIR;
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return description;
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}
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static ErrorOr<void> check_blocked_read(OpenFileDescription* description)
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{
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if (description->is_blocking()) {
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if (!description->can_read()) {
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auto unblock_flags = BlockFlags::None;
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if (Thread::current()->block<Thread::ReadBlocker>({}, *description, unblock_flags).was_interrupted())
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return EINTR;
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if (!has_flag(unblock_flags, BlockFlags::Read))
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return EAGAIN;
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// TODO: handle exceptions in unblock_flags
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}
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}
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return {};
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}
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ErrorOr<FlatPtr> Process::sys$readv(int fd, Userspace<const struct iovec*> iov, int iov_count)
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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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if (iov_count < 0)
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return EINVAL;
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// Arbitrary pain threshold.
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if (iov_count > (int)MiB)
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return EFAULT;
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u64 total_length = 0;
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Vector<iovec, 32> vecs;
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TRY(vecs.try_resize(iov_count));
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TRY(copy_n_from_user(vecs.data(), iov, iov_count));
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for (auto& vec : vecs) {
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total_length += vec.iov_len;
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if (total_length > NumericLimits<i32>::max())
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return EINVAL;
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}
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auto description = TRY(open_readable_file_description(fds(), fd));
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int nread = 0;
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for (auto& vec : vecs) {
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TRY(check_blocked_read(description));
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auto buffer = TRY(UserOrKernelBuffer::for_user_buffer((u8*)vec.iov_base, vec.iov_len));
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auto nread_here = TRY(description->read(buffer, vec.iov_len));
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nread += nread_here;
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}
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return nread;
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}
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ErrorOr<FlatPtr> Process::sys$read(int fd, Userspace<u8*> buffer, size_t size)
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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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if (size == 0)
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return 0;
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if (size > NumericLimits<ssize_t>::max())
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return EINVAL;
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dbgln_if(IO_DEBUG, "sys$read({}, {}, {})", fd, buffer.ptr(), size);
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auto description = TRY(open_readable_file_description(fds(), fd));
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TRY(check_blocked_read(description));
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auto user_buffer = TRY(UserOrKernelBuffer::for_user_buffer(buffer, size));
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return TRY(description->read(user_buffer, size));
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}
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ErrorOr<FlatPtr> Process::sys$pread(int fd, Userspace<u8*> buffer, size_t size, Userspace<off_t*> userspace_offset)
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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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if (size == 0)
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return 0;
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if (size > NumericLimits<ssize_t>::max())
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return EINVAL;
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off_t offset;
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TRY(copy_from_user(&offset, userspace_offset));
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if (offset < 0)
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return EINVAL;
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dbgln_if(IO_DEBUG, "sys$pread({}, {}, {}, {})", fd, buffer.ptr(), size, offset);
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auto description = TRY(open_readable_file_description(fds(), fd));
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if (!description->file().is_seekable())
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return EINVAL;
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TRY(check_blocked_read(description));
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auto user_buffer = TRY(UserOrKernelBuffer::for_user_buffer(buffer, size));
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return TRY(description->read(user_buffer, offset, size));
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}
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}
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