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Martijn Dekker 952944197f Fix bugs in testing if a parameter is set
This fixes three related bugs:
1. Expansions like ${var+set} remained static when used within a
   'for', 'while' or 'until' loop; the expansions din't change
   along with the state of the variable, so they could not be used
   to check whether a variable is set within a loop if the state of
   that variable changed in the course of the loop. (BUG_ISSETLOOP)
2. ${IFS+s} always yielded 's', and [[ -v IFS ]] always yielded
   true, even if IFS is unset. (BUG_IFSISSET)
3. IFS was incorrectly exempt from '-u' ('-o nounset') checks.

src/cmd/ksh93/sh/macro.c: varsub():
- When getting a node pointer (np) to the parameter to test,
  special-case IFS by checking if it has a value and not setting
  the pointer if not. The node to IFS always exists, even after
  'unset -v IFS', so before this fix it always followed the code
  path for a parameter that is set. This fixes BUG_IFSISSET for
  ${IFS+s} and also fixes set -u (-o nounset) with IFS.
- Before using the 'nv_isnull' macro to check if a regular variable
  is set, call nv_optimize() if needed. This fixes BUG_ISSETLOOP.
  Idea from Kurtis Rader: https://github.com/att/ast/issues/1090
  Of course this only works if SHOPT_OPTIMIZE==1 (the default),
  but if not, then this bug is not triggered in the first place.
- Add some comments for future reference.

src/cmd/ksh93/bltins/test.c: test_unop():
- Fix BUG_IFSISSET for [[ -v IFS ]]. The nv_optimize() method
  doesn't seem to have any effect here, so the only way that I can
  figure out is to special-case IFS, nv_getval()'ing it to check if
  IFS has a value in the current scope.

src/cmd/ksh93/tests/variables.sh:
- Add regression tests for checking if a varariable is set within a
  loop, within and outside a function with that variable made local
  (to check if the scope is honoured). Repeat these tests for a
  regular variable and for IFS, for ${foo+set} and [[ -v foo ]].

(cherry picked from commit a2cf79cb98fa3e47eca85d9049d1d831636c9b16)
2020-06-12 01:45:14 +02:00

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Text

This documents significant changes in the 93u+m branch of AT&T ksh93.
For full details, see the git log at:
https://github.com/modernish/ksh
Any uppercase BUG_* names are modernish shell bug IDs.
2020-05-20:
- Fix BUG_ISSETLOOP. Expansions like ${var+set} remained static when used
within a 'for', 'while' or 'until' loop; the expansions din't change along
with the state of the variable, so they could not be used to check whether a
variable is set within a loop if the state of that variable changed in the
course of the loop.
- Fix BUG_IFSISSET. ${IFS+s} always yielded 's', and [[ -v IFS ]] always
yielded true, even if IFS is unset. This applied to IFS only.
2020-05-19:
- Fix 'command -p'. The -p option causes the operating system's standard
utilities path (as output by 'getconf PATH') to be searched instead of $PATH.
Before this fix, this was broken on non-interactive shells as the internal
variable holding the default PATH value was not correctly initialised.
2020-05-16:
- Fix 'test -t 1', '[ -t 1 ]', '[[ -t 1 ]]' in command substitutions.
Standard output (file descriptor 1) tested as being on a terminal within a
command substitution, which makes no sense as the command substitution is
supposed to be catching standard output.
v=$(echo begincomsub
[ -t 1 ] && echo oops
echo endcomsub)
echo "$v"
This now does not output "oops".
2020-05-14:
- Fix syncing history when print -s -f is used. For example, the
following now correctly adds a 'cd' command to the history:
print -s -f 'cd -- %q\n' "$PWD"
Ref.: https://github.com/att/ast/issues/425
https://github.com/att/ast/pull/442
- Fix BUG_PUTIOERR: Output builtins now correctly detect and report
input/output errors. This allows scripts to check for a nonzero exit
status on the 'print', 'printf' and 'echo' builtins and prevent possible
infinite loops if SIGPIPE is ignored.
- Add a convenient bin/run_ksh_tests script to the source tree that
sets up the necessary environment and runs the ksh regression tests.
2020-05-13:
- Fix BUG_CASELIT: an undocumented 'case' pattern matching misbehaviour that
goes back to the original Bourne shell, but wasn't discovered until 2018.
If a pattern doesn't match as a pattern, it was tried again as a literal
string. This broke common validation use cases, e.g.:
n='[0-9]'
case $n in
( [0-9] ) echo "$n is a number" ;;
esac
would output "[0-9] is a number" as the literal string fallback matches the
pattern. As this misbehaviour was never documented anywhere (not for Bourne,
ksh88, or ksh93), and it was never replicated in other shells (not even in
ksh88 clones pdksh and mksh), it is unlikely any scripts rely on it.
Of course, a literal string fallback, should it be needed, is trivial to
implement correctly without this breakage:
case $n in
( [0-9] | "[0-9]") echo "$n is a number or the number pattern" ;;
esac
Ref.: https://github.com/att/ast/issues/476
- Fix BUG_REDIRIO: ksh used to redirect standard output by default when no
file descriptor was specified with the rarely used '<>' reading/writing
redirection operator. It now redirects standard input by default, as POSIX
specifies and as all other POSIX shells do. To redirect standard output
for reading and writing, you now need '1<>'.
Ref.: https://github.com/att/ast/issues/75
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_07_07