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Restore namespace's parent scope when exiting due to error

Reproducer:

    $ namespace test { x=123; typeset -g x=456; }
    $ echo $x ${.test.x}
    456 123
    $ namespace test { typeset -Q; }
    arch/darwin.i386-64/bin/ksh: typeset: -Q: unknown option
    [usage message snipped for brevity]
    $ echo $x ${.test.x}
    123 123	            <== expected: 123 456
    $ x=789
    $ echo $x ${.test.x}
    789 789                 <== expected: 789 456
    $ # look at that, we never left the namespace...

When prefixing the erroneous 'typeset' with 'command', the problem
does not occur. 'command' disables the properties of special
built-ins such as exit on error. So, when a special built-in exits
on error, the parent scope is not properly resotred.

This bug exists in every ksh93 version with SHOPT_NAMESPACE so far.

src/cmd/ksh93/sh/xec.c: sh_exec():
- Before entering a namespace, use sh_pushcontext and sigsetjmp to
  make sure we return here if sh_exit() is called, e.g. when a
  special builtin throws an error, to ensure the parent scope
  (oldnspace) is restored.

Thanks to @hyenias for making me aware of this bug.
Discussion: https://github.com/ksh93/ksh/issues/479#issuecomment-1140468965
This commit is contained in:
Martijn Dekker 2022-05-29 22:50:24 +01:00
parent 8f14514661
commit f73b8617dd
4 changed files with 28 additions and 2 deletions

5
NEWS
View file

@ -3,6 +3,11 @@ For full details, see the git log at: https://github.com/ksh93/ksh/tree/1.0
Any uppercase BUG_* names are modernish shell bug IDs.
2022-05-29:
- Fixed a bug causing an inconsistent state after a special built-in command
threw an error within a namespace.
2022-05-27:
- Fixed a bug introduced on 2022-03-05 where 'set --default', while turning

View file

@ -21,7 +21,7 @@
#define SH_RELEASE_FORK "93u+m" /* only change if you develop a new ksh93 fork */
#define SH_RELEASE_SVER "1.0.0-beta.2" /* semantic version number: https://semver.org */
#define SH_RELEASE_DATE "2022-05-27" /* must be in this format for $((.sh.version)) */
#define SH_RELEASE_DATE "2022-05-29" /* must be in this format for $((.sh.version)) */
#define SH_RELEASE_CPYR "(c) 2020-2022 Contributors to ksh " SH_RELEASE_FORK
/* Scripts sometimes field-split ${.sh.version}, so don't change amount of whitespace. */

View file

@ -2487,6 +2487,8 @@ int sh_exec(register const Shnode_t *t, int flags)
Namval_t *oldnspace = sh.namespace;
int offset = stktell(stkp);
int flags=NV_NOASSIGN|NV_NOARRAY|NV_VARNAME;
struct checkpt *chkp = (struct checkpt*)stakalloc(sizeof(struct checkpt));
int jmpval;
if(cp)
{
errormsg(SH_DICT,ERROR_exit(1),e_ident,fname);
@ -2511,8 +2513,15 @@ int sh_exec(register const Shnode_t *t, int flags)
dtview(root,sh.var_base);
}
oldnspace = enter_namespace(np);
sh_exec(t->for_.fortre,flags|sh_state(SH_ERREXIT));
/* make sure to restore oldnspace if a special builtin throws an error */
sh_pushcontext(chkp,SH_JMPCMD);
jmpval = sigsetjmp(chkp->buff,1);
if(!jmpval)
sh_exec(t->for_.fortre,flags|sh_state(SH_ERREXIT));
sh_popcontext(chkp);
enter_namespace(oldnspace);
if(jmpval) /* error occurred */
sh_exit(sh.exitval);
break;
}
#endif /* SHOPT_NAMESPACE */

View file

@ -130,5 +130,17 @@ got=$(typeset -p .foo_nam.three)
"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
set +o allexport
# ======
# A namespace's parent scope should be restored after an error occurs.
# https://github.com/ksh93/ksh/issues/479#issuecomment-1140514159
#
# TODO: this test fails when run in a non-forking comsub: the trap
# is not executed -- the zillionth bug with virtual subshells >:-/
exp=$'123 456\n789 456'
got=$(ulimit -t unlimited 2>/dev/null # workaround: force fork
trap 'echo $x ${.test.x}; x=789; echo $x ${.test.x}' EXIT; x=123; namespace test { x=456; set -Q 2>/dev/null; })
[[ $got == "$exp" ]] || err_exit 'Parent scope not restored after special builtin throws error in namespace' \
"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
# ======
exit $((Errors<125?Errors:125))