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286984750e
Now that support for 32-bit x86 has been removed, we don't have to worry about the top half of `off_t`/`u64` values being chopped off when we try to pass them in registers. Therefore, we no longer need the workaround of pointers to stack-allocated values to syscalls. Note that this changes the system call ABI, so statically linked programs will have to be re-linked.
117 lines
4.0 KiB
C++
117 lines
4.0 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/OpenFileDescription.h>
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#include <Kernel/Tasks/Process.h>
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namespace Kernel {
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ErrorOr<FlatPtr> Process::sys$pwritev(int fd, Userspace<const struct iovec*> iov, int iov_count, off_t base_offset)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
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TRY(require_promise(Pledge::stdio));
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if (iov_count < 0)
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return EINVAL;
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if (iov_count > IOV_MAX)
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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_file_description(fd));
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if (!description->is_writable())
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return EBADF;
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// NOTE: Negative offset means "operate like writev" which seeks the file.
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if (base_offset >= 0 && !description->file().is_seekable())
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return EINVAL;
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int nwritten = 0;
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off_t current_offset = base_offset;
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for (auto& vec : vecs) {
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auto buffer = TRY(UserOrKernelBuffer::for_user_buffer((u8*)vec.iov_base, vec.iov_len));
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auto result = do_write(*description, buffer, vec.iov_len, base_offset >= 0 ? current_offset : Optional<off_t> {});
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if (result.is_error()) {
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if (nwritten == 0)
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return result.release_error();
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return nwritten;
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}
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nwritten += result.value();
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current_offset += result.value();
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}
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return nwritten;
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}
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ErrorOr<FlatPtr> Process::do_write(OpenFileDescription& description, UserOrKernelBuffer const& data, size_t data_size, Optional<off_t> offset)
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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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TRY(description.seek(0, SEEK_END));
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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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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 = offset.has_value()
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? description.write(offset.value() + total_nwritten, data.offset(total_nwritten), data_size - total_nwritten)
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: 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().code() == EAGAIN)
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continue;
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if (nwritten_or_error.error().code() == EPIPE)
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Thread::current()->send_signal(SIGPIPE, &Process::current());
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return nwritten_or_error.release_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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ErrorOr<FlatPtr> Process::sys$write(int fd, Userspace<u8 const*> data, size_t size)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
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TRY(require_promise(Pledge::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 = TRY(open_file_description(fd));
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if (!description->is_writable())
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return EBADF;
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auto buffer = TRY(UserOrKernelBuffer::for_user_buffer(data, static_cast<size_t>(size)));
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return do_write(*description, buffer, size);
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}
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}
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