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Fix bugs in testing if a parameter is set

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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)
This commit is contained in:
Martijn Dekker 2020-05-20 15:50:43 +01:00
parent 2887378ae3
commit 952944197f
6 changed files with 92 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

21
src/cmd/ksh93/sh/macro.c
View file

@ -1306,7 +1306,15 @@ retry1:
{
if(mp->shp->argaddr)
flag &= ~NV_NOADD;
np = nv_open(id,mp->shp->var_tree,flag|NV_NOFAIL);
/*
* Get a node pointer (np) to the parameter, if any.
*
* The IFS node always exists, so we must special-case IFS by checking if it has
* a value; otherwise it always follows the code path for a set parameter, so is
* not subject to 'set -u', and may test as set even after 'unset -v IFS'.
*/
if(!(*id=='I' && strcmp(id,"IFS")==0 && nv_getval(sh_scoped(mp->shp,IFSNOD)) == NULL))
np = nv_open(id,mp->shp->var_tree,flag|NV_NOFAIL);
if(!np)
{
sfprintf(mp->shp->strbuf,"%s%c",id,0);
@ -1393,8 +1401,12 @@ retry1:
if((type==M_VNAME||type==M_SUBNAME) && mp->shp->argaddr && strcmp(nv_name(np),id))
mp->shp->argaddr = 0;
c = (type>M_BRACE && isastchar(mode));
/*
* Check if the parameter is set or unset.
*/
if(np && (type==M_TREE || !c || !ap))
{
/* The parameter is set. */
char *savptr;
c = *((unsigned char*)stkptr(stkp,offset-1));
savptr = stkfreeze(stkp,0);
@ -1430,7 +1442,13 @@ retry1:
if(ap)
v = nv_arrayisset(np,ap)?(char*)"x":0;
else
{
#if SHOPT_OPTIMIZE
if(mp->shp->argaddr)
nv_optimize(np); /* avoid BUG_ISSETLOOP */
#endif /* SHOPT_OPTIMIZE */
v = nv_isnull(np)?0:(char*)"x";
}
}
else
v = nv_getval(np);
@ -1446,6 +1464,7 @@ retry1:
}
else
{
/* The parameter is unset. */
if(sh_isoption(SH_NOUNSET) && !isastchar(mode) && (type==M_VNAME || type==M_SIZE))
errormsg(SH_DICT,ERROR_exit(1),e_notset,id);
v = 0;