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047cb3303c
Functions can now be correctly redefined and unset in subshell
environments (such as ( ... ), $(command substitutions), etc).
Before this fix, attempts to do this were silently ignored (!!!),
causing the wrong code (i.e.: the function by the same name from
the parent shell environment) to be executed.
Redefining and unsetting functions within "shared" command
substitutions of the form '${ ...; }' is also fixed.
Prior discussion: https://github.com/att/ast/issues/73
src/cmd/ksh93/sh/parse.c:
- A fix from George Koelher (URL above). He writes:
| The parser can set t->comnamp to the wrong function.
| Suppose that the shell has executed
| foo() { echo WRONG; }
| and is now parsing
| (foo() { echo ok; } && foo)
| The parser was setting t->comnamp to the wrong foo. [This
| fix] doesn't set t->comnamp unless it was a builtin. Now the
| subshell can't call t->comnamp, so it looks for foo and finds
| the ok foo in the subshell's function tree.
src/cmd/ksh93/bltins/typeset.c:
- Unsetting functions in a virtual/non-forked subshell still
doesn't work: nv_open() fails to find the function. To work
around this problem, make 'unset -f' fork the subshell into its
own process with sh_subfork().
- The workaround exposed another bug: if we unset a function in a
subshell tree that overrode a function by the same name in the
main shell, then nv_delete() exposes the function from the main
shell scope. Since 'unset -f' now always forks a subshell, the
fix is to simply walk though troot's parent views and delete any
such zombie functions as well. (Without this, the 4 'more fun'
tests in tests/subshell.sh fail.)
src/cmd/ksh93/sh/subshell.c: sh_subfuntree():
- Fix function (re)definitions and unsetting in "shared" command
substitutions of the form '${ commandlist; }' (i.e.: if
sp->shp->subshare is true). Though internally this is a weird
form of virtual subshell, the manual page says it does not
execute in a subshell (meaning, all changes must survive it), so
a subshell function tree must not be created for these.
src/cmd/ksh93/tests/subshell.sh:
- Add regression tests related to these bugfixes. Test unsetting
and redefining a function in all three forms of virtual subshell.
(cherry picked from commit dde387825ab1bbd9f2eafc5dc38d5fd0bf9c3652)
82 lines
3.9 KiB
Text
82 lines
3.9 KiB
Text
TODO for AT&T ksh93, 93u+m bugfix branch
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______
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Fix or remove broken default aliases:
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- Remove alias times='{ { time;} 2>&1;}' which does not produce POSIX-
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compliant output; reimplement as a proper POSIX-compliant builtin.
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In any case, implementing a standard utility as an alias is unacceptable
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as 'unalias -a' (remove all aliases) should not remove standard utilities!
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Backport the builtin from the abandoned Vashisht/Rader branch:
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https://github.com/att/ast/pull/1332
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- Remove alias command='command '. Continuing alias substitution after
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'command' (due to the final space in the alias) is inherently broken, as
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aliases may contain arbitrary shell grammar. For instance, when combining
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this default alias with the default 'times' alias ('command times'), which
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is perfectly valid per POSIX, you get a syntax error!
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- Remove alias nohup='nohup '. Same reason as for 'command ' above.
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- Remove pointless default aliases 'fc' and 'type'; these are already
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implemented as normal shell builtins. Add man page entries for these.
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______
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Fix currently known bugs affecting shell scripting. These are identified by
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their modernish IDs. For exact details, see code/comments in:
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https://github.com/modernish/modernish/tree/0.16/lib/modernish/cap/
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- BUG_BRACQUOT: shell quoting within bracket patterns has no effect. This
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bug means the '-' retains it special meaning of 'character range', and an
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initial ! (and, on some shells, ^) retains the meaning of negation, even
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in quoted strings within bracket patterns, including quoted variables.
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- BUG_CMDEXPAN: if the 'command' command results from an expansion, it acts
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like 'command -v', showing the path of the command instead of executing it.
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For example:
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v=command; "$v" ls
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or
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set -- command ls; "$@"
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don't work.
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- BUG_CMDSPASGN: preceding a "special builtin"[*] with 'command' does not
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stop preceding invocation-local variable assignments from becoming global.
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[*] https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_14
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- BUG_CMDSPEXIT: preceding a "special builtin"[*] (other than 'eval', 'exec',
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'return' or 'exit') with 'command' does not always stop it from exiting
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the shell if the builtin encounters error.
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[*] https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_14
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- BUG_CSUBSTDO: If standard output (file descriptor 1) is closed before
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entering a $(command substitution), and any other file descriptors are
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redirected within the command substitution, commands such as 'echo' will
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not work within the command substitution, acting as if standard output is
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still closed.
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- BUG_IFSGLOBS: In glob pattern matching (as in case or parameter
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substitution with # and %), if IFS starts with ? or * and the "$*"
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parameter expansion inserts any IFS separator characters, those characters
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are erroneously interpreted as wildcards when quoted "$*" is used as the
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glob pattern.
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- BUG_KUNSETIFS: ksh93: Can't unset IFS under very specific circumstances.
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unset -v IFS is a known POSIX shell idiom to activate default field
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splitting. With this bug, the unset builtin silently fails to unset IFS
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(i.e. fails to activate field splitting) if we're executing an eval or a
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trap and a number of specific conditions are met.
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- BUG_LOOPRET2: If a 'return' command is given without a status argument
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within the set of conditional commands in a 'while' or 'until' loop (i.e.,
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between 'while'/'until' and 'do'), the exit status passed down from the
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previous command is ignored and the function returns with status 0
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instead.
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- BUG_MULTIBIFS: We're on a UTF-8 locale and the shell supports UTF-8
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characters in general (i.e. we don't have WRN_MULTIBYTE) – however, using
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multi-byte characters as IFS field delimiters still doesn't work. For
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example, "$*" joins positional parameters on the first byte of IFS instead
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of the first character.
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- BUG_TESTERR1A: test/[ exits with a non-error false status (1) if an
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invalid argument is given to an operator.
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