Fix 'command -p' lookup if hash table entry exists (re: c9ccee86)

If a command's path was previously added to the hash table as a
'tracked alias', then the hash table entry was used, bypassing
the default utility path search activated by 'command -p'.

'command -p' activates a SH_DEFPATH shell state. The bug was caused
by a failure to check for this state before using the hash table.
This check needs to be added in four places.

src/cmd/ksh93/sh/path.c,
src/cmd/ksh93/sh/xec.c:
- path_search(), path_spawn(), sh_exec(), sh_ntfork(): Only consult
  the hash table, which is shp->track_tree, if the SH_DEFPATH shell
  state is not active.

src/cmd/ksh93/tests/path.sh:
- Add regress tests checking that 'command -p' and 'command -p -v'
  still search in the default path if a hash table entry exists for
  the command searched.

NEWS

@@ -3,6 +3,12 @@ For full details, see the git log at: https://github.com/ksh93/ksh
 
 Any uppercase BUG_* names are modernish shell bug IDs.
 
+2020-08-17:
+
+- 'command -p' incorrectly used the hash table entry (a.k.a. tracked alias)
+  for a command if its path was previously hashed. It has now been fixed so
+  it never consults the hash table.
+
 2020-08-16:
 
 - Fixed 'command -x' on macOS, Linux and Solaris by accounting for a 16-byte

src/cmd/ksh93/include/version.h

@@ -17,4 +17,4 @@
 *                  David Korn <dgk@research.att.com>                   *
 *                                                                      *
 ***********************************************************************/
-#define SH_RELEASE	"93u+m 2020-08-13"
+#define SH_RELEASE	"93u+m 2020-08-17"

src/cmd/ksh93/sh/path.c

@@ -696,7 +696,12 @@ int	path_search(Shell_t *shp,register const char *name,Pathcomp_t **oldpp, int f
 		path_init(shp);
 	if(flag)
 	{
-		if(!(flag&1) && (np=nv_search(name,shp->track_tree,0)) && !nv_isattr(np,NV_NOALIAS) && (pp=(Pathcomp_t*)np->nvalue.cp))
+		/* if a tracked alias exists and we're not searching the default path, use it */
+		if(!sh_isstate(SH_DEFPATH)
+		&& !(flag&1)
+		&& (np=nv_search(name,shp->track_tree,0))
+		&& !nv_isattr(np,NV_NOALIAS)
+		&& (pp=(Pathcomp_t*)np->nvalue.cp))
 		{
 			stakseek(PATH_OFFSET);
 			path_nextcomp(shp,pp,name,pp);
@@ -1070,7 +1075,8 @@ pid_t path_spawn(Shell_t *shp,const char *opath,register char **argv, char **env
 	pidsize = sfprintf(stkstd,"*%d*",spawn?getpid():getppid());
 	stakputs(opath);
 	opath = stakfreeze(1)+PATH_OFFSET+pidsize;
-	np=nv_search(argv[0],shp->track_tree,0);
+	/* only use tracked alias if we're not searching default path */
+	np = sh_isstate(SH_DEFPATH) ? NIL(Namval_t*) : nv_search(argv[0],shp->track_tree,0);
 	while(libpath && !libpath->lib)
 		libpath=libpath->next;
 	if(libpath && (!np || nv_size(np)>0))

src/cmd/ksh93/sh/xec.c

@@ -1221,7 +1221,11 @@ int sh_exec(register const Shnode_t *t, int flags)
 					}
 					else
 					{
-						if((np=nv_search(com0,shp->track_tree,0)) && !nv_isattr(np,NV_NOALIAS) && np->nvalue.cp)
+						/* if a tracked alias exists and we're not searching the default path, use it */
+						if(!sh_isstate(SH_DEFPATH)
+						&& (np=nv_search(com0,shp->track_tree,0))
+						&& !nv_isattr(np,NV_NOALIAS)
+						&& np->nvalue.cp)
 							np=nv_search(nv_getval(np),shp->bltin_tree,0);
 						else
 							np = 0;
@@ -3639,7 +3643,11 @@ static pid_t sh_ntfork(Shell_t *shp,const Shnode_t *t,char *argv[],int *jobid,in
 		if(!strchr(path=argv[0],'/')) 
 		{
 			Namval_t *np;
-			if((np=nv_search(path,shp->track_tree,0)) && !nv_isattr(np,NV_NOALIAS) && np->nvalue.cp)
+			/* if a tracked alias exists and we're not searching the default path, use it */
+			if(!sh_isstate(SH_DEFPATH)
+			&& (np=nv_search(path,shp->track_tree,0))
+			&& !nv_isattr(np,NV_NOALIAS)
+			&& np->nvalue.cp)
 				path = nv_getval(np);
 			else if(path_absolute(shp,path,NIL(Pathcomp_t*)))
 			{

src/cmd/ksh93/tests/path.sh

@@ -404,8 +404,10 @@ END
 
 # ======
 # Check that 'command -p' searches the default OS utility PATH.
-v=$(PATH=/dev/null "$SHELL" -c 'command -p ls /dev/null')
-[[ $v == /dev/null ]] || err_exit 'command -p fails to find standard utility'
+expect=/dev/null
+actual=$(PATH=/dev/null "$SHELL" -c 'command -p ls /dev/null' 2>&1)
+[[ $actual == "$expect" ]] || err_exit 'command -p fails to find standard utility' \
+	"(expected $(printf %q "$expect"), got $(printf %q "$actual"))"
 
 # ksh segfaults if $PATH contains a .paths directory
 mkdir -p $tmp/paths-dir-crash/
@@ -416,6 +418,21 @@ print ok
 EOF
 [[ $($SHELL $tmp/paths-dir-crash/run.sh 2>/dev/null) == ok ]] || err_exit "ksh crashes if PATH contains a .paths directory"
 
+# Check that 'command -p' and 'command -p -v' do not use the hash table (a.k.a. tracked aliases).
+print 'echo "wrong path used"' > $tmp/ls
+chmod +x $tmp/ls
+expect=/dev/null
+actual=$(PATH=$tmp; redirect 2>&1; hash ls; command -p ls /dev/null)
+[[ $actual == "$expect" ]] || err_exit "'command -p' fails to search default path if tracked alias exists" \
+	"(expected $(printf %q "$expect"), got $(printf %q "$actual"))"
+actual=$(PATH=$tmp; redirect 2>&1; hash ls; command -p ls /dev/null; exit)  # the 'exit' disables subshell optimization
+[[ $actual == "$expect" ]] || err_exit "'command -p' fails to search default path if tracked alias exists" \
+	"(expected $(printf %q "$expect"), got $(printf %q "$actual"))"
+expect=$(builtin getconf; PATH=$(getconf PATH); whence -p ls)
+actual=$(PATH=$tmp; redirect 2>&1; hash ls; command -p -v ls)
+[[ $actual == "$expect" ]] || err_exit "'command -p -v' fails to search default path if tracked alias exists" \
+	"(expected $(printf %q "$expect"), got $(printf %q "$actual"))"
+
 # ======
 exit $((Errors<125?Errors:125))