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8e97419b0b
This counter is documented as follows:
"The current depth for subshells and command substitution."
But before this commit, the actual behaviour was that the counter
was reset to zero whenever a subshell forked for any reason: a
pipe, background job, running 'ulimit', redirecting stdout in a
command substitution, and more. This behaviour was:
1. Not consistent with the documentation. Non-forked (a.k.a.
virtual) subshells are an internal implementation detail which
scripts should not have to be concerned with. The manual page
doesn't mention them at all.
2. Inherently broken. Since a subshell may fork for any number of
reasons, even mid-run, and those reasons may change with
bugfixes and further development, scripts have never actually
been able to rely on the value of ${.sh.subshell}.
So, this commit fixes the counter to count the levels of all
subshells, both virtual and forked.
src/cmd/ksh93/sh/xec.c: _sh_fork():
- Increase ${.sh.subshell} whenever we fork.
src/cmd/ksh93/sh/subshell.c:
- sh_subfork():
* Fix comment to properly explain what it does. It doesn't
"create" a subshell, it forks off an existing virtual subshell.
* Don't zero ${.sh.subshell}. Instead, since sh_fork() increases
it but we're forking an existing subshell, undo the increase.
- sh_subshell():
* Remove 'int16_t subshell' variable. It was unnecessary and
mostly unused. It was also the wrong type: it was assigned the
value from shp->subshell which is of type short.
* Increase and decrease the level of virtual subshells and
${.sh.subshell} independently.
src/cmd/ksh93/tests/variables.sh:
- Add regression tests for ${.sh.subshell} in virtual and forked
subshells of several kinds: comsub, parentheses, pipe, bg job.
- Undo wrong error test count fix from 04b4aef0.
(cherry picked from commit a0e0e29e7e0dbf21e4b3958ae02bde6665fb2696)
148 lines
6 KiB
Text
148 lines
6 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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2020-06-05:
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- Fix a bug that caused special variables such as PATH, LANG, LC_ALL,
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etc. to lose their effect after being unset in a subshell. For example:
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(unset PATH; PATH=/dev/null; ls); : wrongly ran 'ls'
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(unset LC_ALL; LC_ALL=badlocale); : failed to print a diagnostic
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- Fix crashes on some systems, including at least a crash in 'print -v' on
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macOS, by eliminating an invalid/undefined use of memccpy() on overlapping
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buffers in the commonly used sfputr() function.
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- Fix the ${.sh.subshell} level counter; it is no longer reset to zero when a
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non-forked subshell happens to fork into a separate process for some reason
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(an internal implementation detail that should be unnoticeable to scripts).
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2020-06-04:
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- Fix BUG_KBGPID: the $! special parameter was not set if a background job
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(somecommand &) or co-process (somecommand |&) was launched as the only
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command within a braces block with an attached redirection, for example:
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{
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somecommand &
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} >&2
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With the bug, $! was unchanged; now it contains the PID of somecommand.
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2020-05-31:
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- Fix a bug in autoloading functions. Directories in the path search list
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which should be skipped (e.g. because they don't exist) did not interact
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correctly with autoloaded functions, so that a function to autoload was
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not always found correctly.
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Details: https://github.com/att/ast/issues/1454
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2020-05-30:
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- Fix POSIX compliance of 'test'/'[' exit status on error. The command now
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returns status 2 instead of 1 when given an invalid number or arithmetic
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expression, e.g.:
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[ 123 -eq 123x ]; echo $?
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now outputs 2 instead of 1.
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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 vulnerability 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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