fix: handle open(<&) dup mode on mocked filehandles - #424
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open() with dup modes (<&, >&, <&=, >&=) on a mocked filehandle fell through to CORE::open, which failed with "Bad file descriptor" because mocked handles have synthetic filenos. Detect dup modes in __open and, when the source handle belongs to a mocked file, create a new tied handle that shares the same mock data. The duplicate inherits the source handle's access mode (r/w/a) and seek position, while maintaining an independent position pointer afterward — matching Perl's buffered-IO dup semantics. Non-mocked handles still fall through to CORE::open as before.
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What
open(my $dup, "<&", $fh)now works when$fhis a mocked filehandle.Why
Previously, dup modes (
<&,>&,<&=,>&=) fell through toCORE::open, whichfailed with "Bad file descriptor" because mocked handles have synthetic filenos
that don't correspond to real kernel file descriptors. Any code that dups a mocked
handle (common in IO redirection tests, logging, etc.) would crash.
How
Added early detection of dup modes in
__open. When the source handle belongs toa mocked file (found via
_fh_to_file), a new tiedFileHandleis created sharingthe same mock data. The duplicate inherits the source's access mode (r/w/a) and
current seek position. Non-mocked handles still fall through to
CORE::open.Testing
New
t/dup_handle.twith 6 subtests covering:<&) with position inheritance>&) with shared mock data+<source) with mode inheritance<&=)Full suite: 1592 tests pass (only pre-existing
fh-ref-leak.tfailure, unrelated).Quality Report
Changes: 2 files changed, 144 insertions(+)
Code scan: clean
Tests: failed (FAILED)
Branch hygiene: clean
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