tree eb2b0b40049db294c429bc1151309fc8a26230a2
parent d4011d903b96fd6c6d16fc7407a4678afe1c24cb
author peter klausler <pklausler@nvidia.com> 1616533020 -0700
committer Copybara-Service <copybara-worker@google.com> 1616703970 -0700

[flang] Fix output buffering bug (positionability assumption)

The I/O runtime library code was failing to retain data in a buffer
from the current output record when flushing the buffer; this is
fatally wrong when the corresponding file cannot be repositioned,
as in the case of standard output to the console. So refine the
Flush() member function to retain a specified number of bytes,
rearrange the data as necessary (using existing code for read frame
management after moving it into a new member function), and add
a big comment to the head of the file to clarify the roles of the
various data members in the management of contiguous frames in
circular buffers.

Update: added a unit test.

Differential Revision: https://reviews.llvm.org/D99198

GitOrigin-RevId: 5da55bfc18f64b7171be150913e2f5eac6e0f184