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https://github.com/RGBCube/serenity
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7c87891c06
Instead of copying a Vector everytime we need to enumerate a Process' file descriptions, we can just temporarily lock so it won't change.
120 lines
3.6 KiB
C++
120 lines
3.6 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 <AK/NumericLimits.h>
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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$writev(int fd, Userspace<const struct iovec*> iov, int iov_count)
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{
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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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if (!vecs.try_resize(iov_count))
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return ENOMEM;
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if (!copy_n_from_user(vecs.data(), iov, iov_count))
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return EFAULT;
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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 = fds().file_description(fd);
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if (!description)
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return EBADF;
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if (!description->is_writable())
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return EBADF;
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int nwritten = 0;
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for (auto& vec : vecs) {
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auto buffer = UserOrKernelBuffer::for_user_buffer((u8*)vec.iov_base, vec.iov_len);
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if (!buffer.has_value())
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return EFAULT;
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auto result = do_write(*description, buffer.value(), vec.iov_len);
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if (result.is_error()) {
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if (nwritten == 0)
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return result.error();
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return nwritten;
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}
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nwritten += result.value();
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}
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return nwritten;
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}
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KResultOr<FlatPtr> Process::do_write(FileDescription& description, const UserOrKernelBuffer& data, size_t data_size)
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{
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size_t total_nwritten = 0;
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if (description.should_append() && description.file().is_seekable()) {
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auto seek_result = description.seek(0, SEEK_END);
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if (seek_result.is_error())
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return seek_result.error();
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}
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while (total_nwritten < data_size) {
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while (!description.can_write()) {
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if (!description.is_blocking()) {
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if (total_nwritten > 0)
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return total_nwritten;
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else
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return EAGAIN;
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}
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auto unblock_flags = Thread::FileBlocker::BlockFlags::None;
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if (Thread::current()->block<Thread::WriteBlocker>({}, description, unblock_flags).was_interrupted()) {
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if (total_nwritten == 0)
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return EINTR;
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}
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// TODO: handle exceptions in unblock_flags
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}
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auto nwritten_or_error = description.write(data.offset(total_nwritten), data_size - total_nwritten);
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if (nwritten_or_error.is_error()) {
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if (total_nwritten > 0)
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return total_nwritten;
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if (nwritten_or_error.error() == EAGAIN)
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continue;
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return nwritten_or_error.error();
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}
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VERIFY(nwritten_or_error.value() > 0);
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total_nwritten += nwritten_or_error.value();
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}
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return total_nwritten;
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}
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KResultOr<FlatPtr> Process::sys$write(int fd, Userspace<const u8*> data, size_t size)
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{
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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$write({}, {}, {})", fd, data.ptr(), size);
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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_writable())
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return EBADF;
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auto buffer = UserOrKernelBuffer::for_user_buffer(data, static_cast<size_t>(size));
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if (!buffer.has_value())
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return EFAULT;
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return do_write(*description, buffer.value(), size);
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}
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}
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