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cde/src/cmd
Martijn Dekker 6304dfce41 Fix corner-case >&- redirection leak out of subshell
Reproducer:

    exec 9>&1
    ( { exec 9>&1; } 9>&- )
    echo "test" >&9 # => 9: cannot open [Bad file descriptor]

The 9>&- incorrectly persists beyond the { } block that it
was attached to *and* beyond the ( ) subshell. This is yet another
bug with non-forking subshells; forking it with something like
'ulimit -t unlimited' works around the bug.

In over a year we have not been able to find a real fix, but I came
up with a workaround that forks a virtual subshell whenever it
executes a code block with a >&- or <&- redirection attached. That
use case is obscure enough that it should not cause any performance
regression except in very rare corner cases.

src/cmd/ksh93/sh/xec.c: sh_exec(): TSETIO:
- This is where redirections attached to code blocks are handled.
  Check for a >&- or <&- redirection using bit flaggery from
  shnodes.h and fork if we're executing such in a virtual subshell.

Resolves: https://github.com/ksh93/ksh/issues/161
Thanks to @ko1nksm for the bug report.
2022-02-17 19:35:47 +00:00
..
builtin iffe: really abort on output{ fail (re: e20c0c6b, e72543a, b6bd981) 2022-01-01 02:28:27 +00:00
INIT Update copyright years in files changed since 1st Jan 2022 2022-01-30 20:49:04 +00:00
ksh93 Fix corner-case >&- redirection leak out of subshell 2022-02-17 19:35:47 +00:00
Mamfile **/Mamfile: add header comment pointing to MAM docs (re: 6cc2f6a0) 2021-01-25 14:38:58 +00:00