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ec888867fd
Aliases can now be correctly unset within subshell environments
(such as ( ... ), $(command substitutions), etc), as well as
non-subshell "shared" command substitutions (${ ...; }). Before,
attempts to unset aliases within these were silently ignored.
Prior discussion: https://github.com/att/ast/issues/108
Subshell alias trees are only referenced in a few places in the
code, *and* have always been broken, so this commit gets rid of the
whole notion of a subshell alias tree. Instead, there is now just
one flat alias tree, and subshells fork into a separate process
when aliases are set or unset within them. It is not really
conceivable that this could be a performance-sensitive operation,
or even a common one, so this is a clean fix with no downside.
src/cmd/ksh93/include/defs.h:
- Remove sh_subaliastree() definition.
src/cmd/ksh93/sh/subshell.c:
- Remove salias element (pointer to subshell alias tree) from
subshell struct.
- Remove sh_subaliastree() function.
- sh_subshell(): Remove alias subshell tree cleanup.
src/cmd/ksh93/bltins/typeset.c:
- b_alias(): If in subshell, fork before setting alias.
- b_unalias(): If in subshell, fork before unsetting alias.
- unall(): Remove sh_subaliastree() call.
src/cmd/ksh93/sh/name.c:
- nv_open(): Remove sh_subaliastree() call.
src/cmd/ksh93/tests/subshell.sh:
- Add regression tests for unsetting or redefining aliases within
subshells.
(cherry picked from commit 12a15605b9521a2564a6e657905705a060e89095)
107 lines
4.5 KiB
Text
107 lines
4.5 KiB
Text
This documents significant changes in the 93u+m branch of AT&T ksh93.
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For full details, see the git log at:
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https://github.com/modernish/ksh
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Any uppercase BUG_* names are modernish shell bug IDs.
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2020-05-29:
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- Fix BUG_FNSUBSH: functions can now be correctly redefined and unset in
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subshell environments (such as ( ... ), $(command substitutions), etc).
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Before this fix, this was silently ignored, causing the function by the
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same name from the parent shell environment to be executed instead.
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fn() { echo mainsh; }
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(fn() { echo subsh; }; fn); fn
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This now correctly outputs "subsh mainsh" instead of "mainsh mainsh".
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ls() { echo "ls executed"; }
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(unset -f ls; ls); ls
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This now correctly lists your directory and then prints "ls executed",
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instead of printing "ls executed" twice.
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- Fix a similar bug with aliases. These can now be correctly unset
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in subshell environments.
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2020-05-21:
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- Fix truncating of files with the combined redirections '<>;file' and
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'<#pattern'. The bug was caused by out-of-sync streams.
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Details and discussion: https://github.com/att/ast/issues/61
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- Patched code injection vulerability CVE-2019-14868. As a result, you can
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no longer use expressions in imported numeric environment variables; only
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integer literals are allowed.
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2020-05-20:
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- Fix BUG_ISSETLOOP. Expansions like ${var+set} remained static when used
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within a 'for', 'while' or 'until' loop; the expansions din't change along
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with the state of the variable, so they could not be used to check whether a
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variable is set within a loop if the state of that variable changed in the
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course of the loop.
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- Fix BUG_IFSISSET. ${IFS+s} always yielded 's', and [[ -v IFS ]] always
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yielded true, even if IFS is unset. This applied to IFS only.
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2020-05-19:
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- Fix 'command -p'. The -p option causes the operating system's standard
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utilities path (as output by 'getconf PATH') to be searched instead of $PATH.
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Before this fix, this was broken on non-interactive shells as the internal
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variable holding the default PATH value was not correctly initialised.
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2020-05-16:
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- Fix 'test -t 1', '[ -t 1 ]', '[[ -t 1 ]]' in command substitutions.
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Standard output (file descriptor 1) tested as being on a terminal within a
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command substitution, which makes no sense as the command substitution is
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supposed to be catching standard output.
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v=$(echo begincomsub
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[ -t 1 ] && echo oops
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echo endcomsub)
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echo "$v"
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This now does not output "oops".
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2020-05-14:
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- Fix syncing history when print -s -f is used. For example, the
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following now correctly adds a 'cd' command to the history:
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print -s -f 'cd -- %q\n' "$PWD"
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Ref.: https://github.com/att/ast/issues/425
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https://github.com/att/ast/pull/442
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- Fix BUG_PUTIOERR: Output builtins now correctly detect and report
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input/output errors. This allows scripts to check for a nonzero exit
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status on the 'print', 'printf' and 'echo' builtins and prevent possible
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infinite loops if SIGPIPE is ignored.
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- Add a convenient bin/run_ksh_tests script to the source tree that
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sets up the necessary environment and runs the ksh regression tests.
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2020-05-13:
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- Fix BUG_CASELIT: an undocumented 'case' pattern matching misbehaviour that
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goes back to the original Bourne shell, but wasn't discovered until 2018.
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If a pattern doesn't match as a pattern, it was tried again as a literal
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string. This broke common validation use cases, e.g.:
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n='[0-9]'
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case $n in
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( [0-9] ) echo "$n is a number" ;;
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esac
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would output "[0-9] is a number" as the literal string fallback matches the
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pattern. As this misbehaviour was never documented anywhere (not for Bourne,
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ksh88, or ksh93), and it was never replicated in other shells (not even in
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ksh88 clones pdksh and mksh), it is unlikely any scripts rely on it.
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Of course, a literal string fallback, should it be needed, is trivial to
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implement correctly without this breakage:
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case $n in
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( [0-9] | "[0-9]") echo "$n is a number or the number pattern" ;;
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esac
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Ref.: https://github.com/att/ast/issues/476
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- Fix BUG_REDIRIO: ksh used to redirect standard output by default when no
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file descriptor was specified with the rarely used '<>' reading/writing
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redirection operator. It now redirects standard input by default, as POSIX
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specifies and as all other POSIX shells do. To redirect standard output
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for reading and writing, you now need '1<>'.
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Ref.: https://github.com/att/ast/issues/75
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http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_07_07
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