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Kernel: Acknowledge partial writes from TTYs

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Fixes a bug where TTY::write will attempt to write into the underlying
device but will not acknowledge the result of that write, instead
assuming that the write fully completed.
This commit is contained in:
Sahan Fernando 2021-05-18 19:06:33 +10:00 • committed by Andreas Kling
parent fe2d4d85c4
commit c3b670c092
1 changed files with 23 additions and 2 deletions
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25
Kernel/TTY/TTY.cpp
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@ -97,8 +97,29 @@ KResultOr<size_t> TTY::write(FileDescription&, u64, const UserOrKernelBuffer& bu
} }
modified_data[i + extra_chars] = ch; modified_data[i + extra_chars] = ch;
} }
on_tty_write(UserOrKernelBuffer::for_kernel_buffer(modified_data), buffer_bytes + extra_chars); ssize_t bytes_written = on_tty_write(UserOrKernelBuffer::for_kernel_buffer(modified_data), buffer_bytes + extra_chars);
return buffer_bytes; VERIFY(bytes_written != 0);
if (bytes_written < 0 || !(m_termios.c_oflag & OPOST) || !(m_termios.c_oflag & ONLCR))
return bytes_written;
if ((size_t)bytes_written == buffer_bytes + extra_chars)
return (ssize_t)buffer_bytes;
// Degenerate case where we converted some newlines and encountered a partial write
// Calculate where in the input buffer the last character would have been
size_t pos_data = 0;
for (ssize_t pos_modified_data = 0; pos_modified_data < bytes_written; ++pos_data) {
if (data[pos_data] == '\n')
pos_modified_data += 2;
else
pos_modified_data += 1;
// Handle case where the '\r' got written but not the '\n'
// FIXME: Our strategy is to retry writing both. We should really be queuing a write for the corresponding '\n'
if (pos_modified_data > bytes_written)
--pos_data;
}
return (ssize_t)pos_data;
}); });
} }