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Kernel: Factor out common code from read/readv syscalls

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Having these bits of code factored out not only prevents duplication
now, but will also allow us to implement pread without repeating
ourselves (too much).
This commit is contained in:
Rodrigo Tobar 2021-10-12 20:59:49 +08:00 committed by Andreas Kling
parent 52976bfac6
commit 8936b111a7
Notes: sideshowbarker 2024-07-18 02:47:26 +09:00 
Author: https://github.com/rtobar
Commit: https://github.com/SerenityOS/serenity/commit/8936b111a73
Pull-request: https://github.com/SerenityOS/serenity/pull/10450
1 changed files with 29 additions and 30 deletions
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59
Kernel/Syscalls/read.cpp
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@ -12,6 +12,31 @@ namespace Kernel {
using BlockFlags = Thread::FileBlocker::BlockFlags;
static KResultOr<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 KResult 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 KSuccess;
}
KResultOr<FlatPtr> Process::sys$readv(int fd, Userspace<const struct iovec*> iov, int iov_count)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
@ -34,24 +59,11 @@ KResultOr<FlatPtr> Process::sys$readv(int fd, Userspace<const struct iovec*> iov
return EINVAL;
}
auto description = TRY(fds().open_file_description(fd));
if (!description->is_readable())
return EBADF;
if (description->is_directory())
return EISDIR;
auto description = TRY(open_readable_file_description(fds(), fd));
int nread = 0;
for (auto& vec : vecs) {
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
}
}
TRY(check_blocked_read(description));
auto buffer = UserOrKernelBuffer::for_user_buffer((u8*)vec.iov_base, vec.iov_len);
if (!buffer.has_value())
return EFAULT;
@ -71,21 +83,8 @@ KResultOr<FlatPtr> Process::sys$read(int fd, Userspace<u8*> buffer, size_t size)
if (size > NumericLimits<ssize_t>::max())
return EINVAL;
dbgln_if(IO_DEBUG, "sys$read({}, {}, {})", fd, buffer.ptr(), size);
auto description = TRY(fds().open_file_description(fd));
if (!description->is_readable())
return EBADF;
if (description->is_directory())
return EISDIR;
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
}
}
auto description = TRY(open_readable_file_description(fds(), fd));
TRY(check_blocked_read(description));
auto user_buffer = UserOrKernelBuffer::for_user_buffer(buffer, size);
if (!user_buffer.has_value())
return EFAULT;