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[1.0 release prep] Remove tilde expansion discipline

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Defining a .sh.tilde.get or .sh.tilde.set discipline function to
extend tilde expansion works well as long as the discipline
function doesn't get interrupted (e.g. with Crtl+C) or produce an
error message. Either of those will cause the shell to become
unstable and crash.

This feature is now removed from the 1.0 branch as it is not ready
for prime time. It can return to a release branch if/when we manage
to fix it on the master branch.

Related: https://github.com/ksh93/ksh/issues/346
This commit is contained in:
Martijn Dekker 2021-11-24 07:46:58 +01:00
parent 40de1e92b0
commit c0334e32a1
9 changed files with 1 additions and 134 deletions
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6
ANNOUNCE
View file

@ -82,12 +82,6 @@ New shell language features:
useful; it now matches all hidden files (dotfiles) in the current
directory, without the harmful inclusion of '.' and '..'.
- Tilde expansion can now be extended or modified by defining a
.sh.tilde.get or .sh.tilde.set discipline function. This replaces a
2004 undocumented attempt to add this functionality via a .sh.tilde
command, which never worked and crashed the shell. See the manual for
details on the new method.
New features in built-in commands:
- Usage error messages now show the --help/--man self-documentation options.

5
NEWS
View file

@ -366,11 +366,6 @@ Any uppercase BUG_* names are modernish shell bug IDs.
2021-03-16:
- Tilde expansion can now be extended or modified by defining a .sh.tilde.get
or .sh.tilde.set discipline function. This replaces a 2004 undocumented
attempt to add this functionality via a .sh.tilde built-in, which never
worked and crashed the shell. See the manual for details on the new method.
- Fixed a bug in interactive shells: if a variable used by the shell called
a discipline function (such as PS1.get() or COLUMNS.set()), the value of $?
was set to the exit status of the discipline function instead of the last

1
src/cmd/ksh93/data/variables.c
View file

@ -104,7 +104,6 @@ const struct shtable2 shtab_variables[] =
".sh.math", 0, (char*)0,
".sh.pool", 0, (char*)0,
".sh.pid", NV_INTEGER|NV_NOFREE, (char*)0,
".sh.tilde", 0, (char*)0,
"SHLVL", NV_INTEGER|NV_NOFREE|NV_EXPORT, (char*)0,
#if SHOPT_MULTIBYTE
"CSWIDTH", 0, (char*)0,

3
src/cmd/ksh93/include/variables.h
View file

@ -104,7 +104,6 @@ extern void sh_save_rand_seed(struct rand *, int);
#define SH_MATHNOD (shgd->bltin_nodes+62)
#define SH_JOBPOOL (shgd->bltin_nodes+63)
#define SH_PIDNOD (shgd->bltin_nodes+64)
#define SH_TILDENOD (shgd->bltin_nodes+65)
#define SHLVL (shgd->bltin_nodes+66)
#define SHLVL (shgd->bltin_nodes+65)
#endif /* SH_VALNOD */

31
src/cmd/ksh93/sh.1
View file

@ -849,37 +849,6 @@ A
.B :
also terminates a user name following a
.BR \(ap .
.PP
The tilde expansion mechanism may be extended or modified
by defining one of the discipline functions
.B .sh.tilde.set
or
.B .sh.tilde.get
(see
.I Functions
and
.I Discipline Functions
below).
If either exists,
then upon encountering a tilde word to expand,
that function is called with the tilde word assigned to either
.B .sh.value
(for the
.B .sh.tilde.set
function) or
.B .sh.tilde
(for the
.B .sh.tilde.get
function).
Performing tilde expansion within a discipline function will not recursively
call that function, but default tilde expansion remains active,
so literal tildes should still be quoted where required.
Either function may assign a replacement string to
.BR .sh.value .
If this value is non-empty and does not start with a
.BR \(ap ,
it replaces the default tilde expansion when the function terminates.
Otherwise, the tilde expansion is left unchanged.
.SS Command Substitution.
The standard output from a command list enclosed in
parentheses preceded by a dollar sign (

16
src/cmd/ksh93/sh/macro.c
View file

@ -2635,23 +2635,7 @@ static void tilde_expand2(Shell_t *shp, register int offset)
char *cp = NIL(char*); /* character pointer for tilde expansion result */
char *stakp = stakptr(0); /* current stack object (&stakp[offset] is tilde string) */
int curoff = staktell(); /* current offset of current stack object */
static char block; /* for disallowing tilde expansion in .get/.set to change ${.sh.tilde} */
/*
* Allow overriding tilde expansion with a .sh.tilde.set or .get discipline function.
*/
if(!block && SH_TILDENOD->nvfun && SH_TILDENOD->nvfun->disc)
{
stakfreeze(1); /* terminate current stack object to avoid data corruption */
block++;
nv_putval(SH_TILDENOD, &stakp[offset], 0);
cp = nv_getval(SH_TILDENOD);
block--;
if(cp[0]=='\0' || cp[0]=='~')
cp = NIL(char*); /* do not use empty or unexpanded result */
stakset(stakp,curoff); /* restore stack to state on function entry */
}
/*
* Perform default tilde expansion unless overridden.
* Write the result to the stack, if any.
*/
stakputc(0);

18
src/cmd/ksh93/tests/pty.sh
View file

@ -751,24 +751,6 @@ r ^:test-2: echo Success\r\n$
r ^Success\r\n$
!
# err_exit #
((SHOPT_VSH || SHOPT_ESH)) && tst $LINENO <<"!"
L value of $? after tilde expansion in tab completion
# Make sure that a .sh.tilde.set discipline function
# cannot influence the exit status.
w .sh.tilde.set() { true; }
w HOME=/tmp
w false ~\t
u false /tmp
w echo "Exit status is: $?"
u Exit status is: 1
w (exit 42)
w echo $? ~\t
u 42 /tmp
!
# err_exit #
((SHOPT_MULTIBYTE && (SHOPT_VSH || SHOPT_ESH))) &&
[[ ${LC_ALL:-${LC_CTYPE:-${LANG:-}}} =~ [Uu][Tt][Ff]-?8 ]] &&

54
src/cmd/ksh93/tests/tilde.sh
View file

@ -107,8 +107,6 @@ got=~
HOME=$saveHOME
# ======
# Tilde expansion discipline function tests
# This nonfunctional mess was removed in ksh 93u+m ...
if builtin .sh.tilde 2>/dev/null
then got=$(.sh.tilde & wait "$!" 2>&1)
@ -116,57 +114,5 @@ then got=$(.sh.tilde & wait "$!" 2>&1)
"(got status $e$( ((e>128)) && print -n / && kill -l "$e"), $(printf %q "$got"))"
fi
# ... and replaced by a proper use of discipline functions that allows customising tilde expansion.
((.sh.version >= 20210316)) &&
for disc in get set
do (
ulimit -t unlimited 2>/dev/null # fork subshell to cope with a possible crash
eval ".sh.tilde.$disc()
{
case \${.sh.${ [[ $disc == get ]] && print tilde || print value; }} in
'~tmp') .sh.value=\$tmp ;;
'~INC') .sh.value=\$((++i)) ;;
'~spc') .sh.value=$'one\ttwo three\n\tfour' ;;
'~') .sh.value=~/addition ;; # this should not recurse
esac
}"
got=~/foo
exp=$HOME/addition/foo
[[ $got == "$exp" ]] || err_exit "$disc discipline: bare tilde expansion:" \
"expected $(printf %q "$exp"), got $(printf %q "$got")"
.sh.tilde=oldvalue
got=$(print ~tmp/foo.$$; print "${.sh.tilde}")
exp=$tmp/foo.$$$'\n'$tmp
[[ $got == "$exp" ]] || err_exit "$disc discipline: result left in \${.sh.tilde}:" \
"expected $(printf %q "$tmp"), got $(printf %q "${.sh.tilde}")"
[[ ${.sh.tilde} == oldvalue ]] || err_exit "$disc discipline: \${.sh.tilde} subshell leak"
i=0
set -- ~INC ~INC ~INC ~INC ~INC
got=$#,$1,$2,$3,$4,$5
exp=5,1,2,3,4,5
[[ $got == "$exp" ]] || err_exit "$disc discipline: counter:" \
"expected $(printf %q "$exp"), got $(printf %q "$got")"
((i==5)) || err_exit "$disc discipline: counter: $i != 5"
set -- ~spc ~spc ~spc
got=$#,$1,$2,$3
exp=$'3,one\ttwo three\n\tfour,one\ttwo three\n\tfour,one\ttwo three\n\tfour'
[[ $got == "$exp" ]] || err_exit "$disc discipline: quoting of whitespace:" \
"expected $(printf %q "$exp"), got $(printf %q "$got")"
print "$Errors" >$tmp/Errors
) &
wait "$!" 2>crashmsg
if ((!(e = $?)))
then read Errors <$tmp/Errors
else err_exit ".sh.tilde.$disc discipline function crashes the shell" \
"(got status $e$( ((e>128)) && print -n / && kill -l "$e"), $(printf %q "$(<crashmsg)"))"
fi
done
# ======
exit $((Errors<125?Errors:125))

1
src/cmd/ksh93/tests/variables.sh
View file

@ -1026,7 +1026,6 @@ set -- \
".sh.math" \
".sh.pool" \
".sh.pid" \
".sh.tilde" \
"SHLVL" \
"CSWIDTH"