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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/FileDescription.h>
#include <Kernel/Process.h>
namespace Kernel {
KResultOr<size_t> Process::sys$writev(int fd, Userspace<const struct iovec*> iov, int iov_count)
{
REQUIRE_PROMISE(stdio);
if (iov_count < 0)
return EINVAL;
// Arbitrary pain threshold.
if (iov_count > (int)MiB)
return EFAULT;
u64 total_length = 0;
Vector<iovec, 32> vecs;
if (!vecs.try_resize(iov_count))
return ENOMEM;
if (!copy_n_from_user(vecs.data(), iov, iov_count))
return EFAULT;
for (auto& vec : vecs) {
total_length += vec.iov_len;
if (total_length > NumericLimits<i32>::max())
return EINVAL;
}
auto description = file_description(fd);
if (!description)
return EBADF;
if (!description->is_writable())
return EBADF;
int nwritten = 0;
for (auto& vec : vecs) {
auto buffer = UserOrKernelBuffer::for_user_buffer((u8*)vec.iov_base, vec.iov_len);
if (!buffer.has_value())
return EFAULT;
auto result = do_write(*description, buffer.value(), vec.iov_len);
if (result.is_error()) {
if (nwritten == 0)
return result.error();
return nwritten;
}
nwritten += result.value();
}
return nwritten;
}
KResultOr<size_t> Process::do_write(FileDescription& description, const UserOrKernelBuffer& data, size_t data_size)
{
size_t total_nwritten = 0;
if (description.should_append() && description.file().is_seekable()) {
auto seek_result = description.seek(0, SEEK_END);
if (seek_result.is_error())
return seek_result.error();
}
while (total_nwritten < data_size) {
while (!description.can_write()) {
if (!description.is_blocking()) {
if (total_nwritten > 0)
return total_nwritten;
else
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 = 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() == EAGAIN)
continue;
return nwritten_or_error.error();
}
VERIFY(nwritten_or_error.value() > 0);
total_nwritten += nwritten_or_error.value();
}
return total_nwritten;
}
KResultOr<size_t> Process::sys$write(int fd, Userspace<const u8*> data, size_t size)
{
REQUIRE_PROMISE(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 = file_description(fd);
if (!description)
return EBADF;
if (!description->is_writable())
return EBADF;
auto buffer = UserOrKernelBuffer::for_user_buffer(data, static_cast<size_t>(size));
if (!buffer.has_value())
return EFAULT;
return do_write(*description, buffer.value(), size);
}
}
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