Joseph Myers 377e9733b5 Fix fflush after ungetc on input file (bug 5994) ...

As discussed in bug 5994 (plus duplicates), POSIX requires fflush
after ungetc to discard pushed-back characters but preserve the file
position indicator.  For this purpose, each ungetc decrements the file
position indicator by 1; it is unspecified after ungetc at the start
of the file, and after ungetwc, so no special handling is needed for
either of those cases.

This is fixed with appropriate logic in _IO_new_file_sync.  I haven't
made any attempt to test or change things in this area for the "old"
functions; the case of files using mmap is addressed in a subsequent
patch (and there seem to be no problems in this area with files opened
with fmemopen).

Tested for x86_64.

2025-01-28 19:38:27 +00:00

2.0 KiB

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