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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/NumericLimits.h>
#include <Kernel/Debug.h>
#include <Kernel/FileSystem/OpenFileDescription.h>
#include <Kernel/Tasks/Process.h>
namespace Kernel {
// NOTE: The offset is passed by pointer because off_t is 64bit,
// hence it can't be passed by register on 32bit platforms.
ErrorOr<FlatPtr> Process::sys$pwritev(int fd, Userspace<const struct iovec*> iov, int iov_count, Userspace<off_t const*> userspace_offset)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
TRY(require_promise(Pledge::stdio));
if (iov_count < 0)
return EINVAL;
if (iov_count > IOV_MAX)
return EFAULT;
u64 total_length = 0;
Vector<iovec, 32> vecs;
TRY(vecs.try_resize(iov_count));
TRY(copy_n_from_user(vecs.data(), iov, iov_count));
for (auto& vec : vecs) {
total_length += vec.iov_len;
if (total_length > NumericLimits<i32>::max())
return EINVAL;
}
// NOTE: Negative offset means "operate like writev" which seeks the file.
auto base_offset = TRY(copy_typed_from_user(userspace_offset));
auto description = TRY(open_file_description(fd));
if (!description->is_writable())
return EBADF;
if (base_offset >= 0 && !description->file().is_seekable())
return EINVAL;
int nwritten = 0;
off_t current_offset = base_offset;
for (auto& vec : vecs) {
auto buffer = TRY(UserOrKernelBuffer::for_user_buffer((u8*)vec.iov_base, vec.iov_len));
auto result = do_write(*description, buffer, vec.iov_len, base_offset >= 0 ? current_offset : Optional<off_t> {});
if (result.is_error()) {
if (nwritten == 0)
return result.release_error();
return nwritten;
}
nwritten += result.value();
current_offset += result.value();
}
return nwritten;
}
ErrorOr<FlatPtr> Process::do_write(OpenFileDescription& description, UserOrKernelBuffer const& data, size_t data_size, Optional<off_t> offset)
{
size_t total_nwritten = 0;
if (description.should_append() && description.file().is_seekable()) {
TRY(description.seek(0, SEEK_END));
}
while (total_nwritten < data_size) {
while (!description.can_write()) {
if (!description.is_blocking()) {
if (total_nwritten > 0)
return total_nwritten;
return EAGAIN;
}
auto unblock_flags = Thread::FileBlocker::BlockFlags::None;
if (Thread::current()->block<Thread::WriteBlocker>({}, description, unblock_flags).was_interrupted()) {
if (total_nwritten == 0)
return EINTR;
}
// TODO: handle exceptions in unblock_flags
}
auto nwritten_or_error = offset.has_value()
? description.write(offset.value() + total_nwritten, data.offset(total_nwritten), data_size - total_nwritten)
: description.write(data.offset(total_nwritten), data_size - total_nwritten);
if (nwritten_or_error.is_error()) {
if (total_nwritten > 0)
return total_nwritten;
if (nwritten_or_error.error().code() == EAGAIN)
continue;
if (nwritten_or_error.error().code() == EPIPE)
Thread::current()->send_signal(SIGPIPE, &Process::current());
return nwritten_or_error.release_error();
}
VERIFY(nwritten_or_error.value() > 0);
total_nwritten += nwritten_or_error.value();
}
return total_nwritten;
}
ErrorOr<FlatPtr> Process::sys$write(int fd, Userspace<u8 const*> data, size_t size)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
TRY(require_promise(Pledge::stdio));
if (size == 0)
return 0;
if (size > NumericLimits<ssize_t>::max())
return EINVAL;
dbgln_if(IO_DEBUG, "sys$write({}, {}, {})", fd, data.ptr(), size);
auto description = TRY(open_file_description(fd));
if (!description->is_writable())
return EBADF;
auto buffer = TRY(UserOrKernelBuffer::for_user_buffer(data, static_cast<size_t>(size)));
return do_write(*description, buffer, size);
}
}
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