From 3e79027cd166bf9e0569671195e94bd2e3a0c4dc Mon Sep 17 00:00:00 2001
From: Martijn Dekker <martijn@inlv.org>
Date: Sun, 24 Jul 2022 07:26:43 +0200
Subject: [PATCH] 'command -x': also bypass path-bound built-ins (re: 66e1d446)

Since 'command -x' provides xargs-like functionality to repeatedly
run external commands if the argument list is too long for one
invocation, it makes little sense to use with built-ins. So I
decided that 'command -x' should double as a way to guarantee
running an external command. However, it was only bypassing plain
built-ins and not path-bound builtins (the ones that show up with a
virtual directory path name in the output of 'builtin').

src/cmd/ksh93/sh/path.c:
- Before looking for a path-bound built-in, check that the SH_XARG
  state bit is not on. This needs to be done in path_absolute() as
  well as in path_spawn().
---
 NEWS                        | 3 +++
 src/cmd/ksh93/sh/path.c     | 4 ++--
 src/cmd/ksh93/tests/path.sh | 9 +++++++++
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/NEWS b/NEWS
index ad0b6ec15..03426fa0e 100644
--- a/NEWS
+++ b/NEWS
@@ -14,6 +14,9 @@ Any uppercase BUG_* names are modernish shell bug IDs.
 - Fixed a bug that caused the -b/--notify option to only notify on one job if
   more than one background job completed at the same time.
 
+- Fixed a bug in the 'command -x' feature introduced on 2021-01-30; it is meant
+  to always run an external command, but failed to bypass path-bound builtins.
+
 2022-07-21:
 
 - Fixed a bug where a reproducible $RANDOM sequence (after assigning a
diff --git a/src/cmd/ksh93/sh/path.c b/src/cmd/ksh93/sh/path.c
index 50d6ad864..4eeee6a35 100644
--- a/src/cmd/ksh93/sh/path.c
+++ b/src/cmd/ksh93/sh/path.c
@@ -757,7 +757,7 @@ Pathcomp_t *path_absolute(register const char *name, Pathcomp_t *pp, int flag)
 			int n;
 #endif
 			/* Handle default path-bound builtins */
-			if(*stakptr(PATH_OFFSET)=='/' && nv_search(stakptr(PATH_OFFSET),sh.bltin_tree,0))
+			if(!sh_isstate(SH_XARG) && *stakptr(PATH_OFFSET)=='/' && nv_search(stakptr(PATH_OFFSET),sh.bltin_tree,0))
 				return(oldpp);
 #if SHOPT_DYNAMIC
 			/* Load builtins from dynamic libraries */
@@ -1054,7 +1054,7 @@ pid_t path_spawn(const char *opath,register char **argv, char **envp, Pathcomp_t
 	char		*s, *v;
 	int		r, n, pidsize;
 	pid_t		pid= -1;
-	if(nv_search(opath,sh.bltin_tree,0))
+	if(!sh_isstate(SH_XARG) && nv_search(opath,sh.bltin_tree,0))
 	{
 		/* Found a path-bound built-in. Since this was not caught earlier in sh_exec(), it must
 		   have been found on a temporarily assigned PATH, as with 'PATH=/opt/ast/bin:$PATH cat'.
diff --git a/src/cmd/ksh93/tests/path.sh b/src/cmd/ksh93/tests/path.sh
index 35f7624d2..d4263213f 100755
--- a/src/cmd/ksh93/tests/path.sh
+++ b/src/cmd/ksh93/tests/path.sh
@@ -518,6 +518,15 @@ then
 		"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
 fi
 
+# Check that adding '-x' runs an external command, also bypassing path-bound builtins
+if	! test -x /opt/ast/bin/cat	# a physical external utility here would invalidate these tests
+then
+	got=$( PATH=/opt/ast/bin; command -x cat --about 2>&1 )
+	[[ $got == *version*'cat ('* ]] && err_exit 'command -x fails to bypass path-bound built-in found in PATH search'
+	got=$( command -x /opt/ast/bin/cat --about 2>&1 )
+	[[ $got == *version*'cat ('* ]] && err_exit 'command -x fails to bypass path-bound built-in by direct pathname'
+fi
+
 # ======
 # 'command -x' used to hang in an endless E2BIG loop on Linux and macOS
 ofile=$tmp/command_x_chunks.sh