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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/Debug.h>
#include <Kernel/FileSystem/OpenFileDescription.h>
#include <Kernel/Process.h>
namespace Kernel {
using BlockFlags = Thread::FileBlocker::BlockFlags;
static ErrorOr<NonnullRefPtr<OpenFileDescription>> open_readable_file_description(Process::OpenFileDescriptions const& fds, int fd)
{
auto description = TRY(fds.open_file_description(fd));
if (!description->is_readable())
return EBADF;
if (description->is_directory())
return EISDIR;
return description;
}
static ErrorOr<void> check_blocked_read(OpenFileDescription* description)
{
if (description->is_blocking()) {
if (!description->can_read()) {
auto unblock_flags = BlockFlags::None;
if (Thread::current()->block<Thread::ReadBlocker>({}, *description, unblock_flags).was_interrupted())
return EINTR;
if (!has_flag(unblock_flags, BlockFlags::Read))
return EAGAIN;
// TODO: handle exceptions in unblock_flags
}
}
return {};
}
ErrorOr<FlatPtr> Process::sys$readv(int fd, Userspace<const struct iovec*> iov, int iov_count)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
TRY(require_promise(Pledge::stdio));
if (iov_count < 0)
return EINVAL;
// Arbitrary pain threshold.
if (iov_count > (int)MiB)
return EFAULT;
u64 total_length = 0;
Vector<iovec, 32> vecs;
TRY(vecs.try_resize(iov_count));
TRY(copy_n_from_user(vecs.data(), iov, iov_count));
for (auto& vec : vecs) {
total_length += vec.iov_len;
if (total_length > NumericLimits<i32>::max())
return EINVAL;
}
auto description = TRY(open_readable_file_description(fds(), fd));
int nread = 0;
for (auto& vec : vecs) {
TRY(check_blocked_read(description));
auto buffer = TRY(UserOrKernelBuffer::for_user_buffer((u8*)vec.iov_base, vec.iov_len));
auto nread_here = TRY(description->read(buffer, vec.iov_len));
nread += nread_here;
}
return nread;
}
ErrorOr<FlatPtr> Process::sys$read(int fd, Userspace<u8*> buffer, 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$read({}, {}, {})", fd, buffer.ptr(), size);
auto description = TRY(open_readable_file_description(fds(), fd));
TRY(check_blocked_read(description));
auto user_buffer = TRY(UserOrKernelBuffer::for_user_buffer(buffer, size));
return TRY(description->read(user_buffer, size));
}
// NOTE: The offset is passed by pointer because off_t is 64bit,
// hence it can't be passed by register on 32bit platforms.
ErrorOr<FlatPtr> Process::sys$pread(int fd, Userspace<u8*> buffer, size_t size, Userspace<off_t const*> userspace_offset)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
TRY(require_promise(Pledge::stdio));
if (size == 0)
return 0;
if (size > NumericLimits<ssize_t>::max())
return EINVAL;
auto offset = TRY(copy_typed_from_user(userspace_offset));
if (offset < 0)
return EINVAL;
dbgln_if(IO_DEBUG, "sys$pread({}, {}, {}, {})", fd, buffer.ptr(), size, offset);
auto description = TRY(open_readable_file_description(fds(), fd));
if (!description->file().is_seekable())
return EINVAL;
TRY(check_blocked_read(description));
auto user_buffer = TRY(UserOrKernelBuffer::for_user_buffer(buffer, size));
return TRY(description->read(user_buffer, offset, size));
}
}
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