From 65189dacb44708743313c81ec1ccaff87a68be8d Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Sat, 15 Dec 2018 15:01:53 +0000
Subject: ash: fix local PATH assignments

The previous commit included code to use PATH values assigned to
local variables:

   PATH=/new/path:$PATH new_binary

It didn't work in the case when no fork was needed, for example:

   (PATH=/new/path:$PATH new_binary)

because the call to listsetvar() freed the PATH value that was
passed to shellexec().  The forking case only worked because the
spawn_forkshell() mechanism in busybox-w32 didn't allow the PATH
value to be freed.

Rewrite the code so it works whether or not a fork is needed.  The
code would also work on POSIX systems.

A cleaner solution could be extracted from dash commit cbb71a8
'eval: Add assignment built-in support again' but neither that nor
the current patch are suitable for submission to upstream BusyBox.
This one is preferred because it requires fewer changes from
upstream.
---
 shell/ash.c | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/shell/ash.c b/shell/ash.c
index a659fd703..5195a8557 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -10531,6 +10531,9 @@ evalcommand(union node *cmd, int flags)
 	int status;
 	char **nargv;
 	smallint cmd_is_exec;
+#if ENABLE_PLATFORM_MINGW32
+	int cmdpath;
+#endif
 
 	errlinno = lineno = cmd->ncmd.linno;
 	if (funcline)
@@ -10599,6 +10602,7 @@ evalcommand(union node *cmd, int flags)
 	}
 	status = redirectsafe(cmd->ncmd.redirect, REDIR_PUSH | REDIR_SAVEFD2);
 
+#if !ENABLE_PLATFORM_MINGW32
 	path = vpath.var_text;
 	for (argp = cmd->ncmd.assign; argp; argp = argp->narg.next) {
 		struct strlist **spp;
@@ -10615,14 +10619,17 @@ evalcommand(union node *cmd, int flags)
 		 */
 		p = (*spp)->text;
 		if (varcmp(p, path) == 0)
-#if !ENABLE_PLATFORM_MINGW32
 			path = p;
+	}
 #else
-			/* fix_pathvar may have modified the value of the local
-			 * variable so we look it up again */
-			path = vpath.var_text;
-#endif
+	/* Set path after any local PATH= has been processed. */
+	for (argp = cmd->ncmd.assign; argp; argp = argp->narg.next) {
+		struct strlist **spp = varlist.lastp;
+		expandarg(argp, &varlist, EXP_VARTILDE);
+		mklocal((*spp)->text);
 	}
+	path = vpath.var_text;
+#endif
 
 	/* Print the command if xflag is set. */
 	if (xflag) {
@@ -10780,7 +10787,13 @@ evalcommand(union node *cmd, int flags)
 			TRACE(("forked child exited with %d\n", status));
 			break;
 		}
-		/* goes through to shellexec() */
+		/* If we're running 'command -p' we need to use the value stored
+		 * in path by parse_command_args().  If PATH is a local variable
+		 * listsetvar() will free the value currently in path so we need
+		 * to fetch the updated version. */
+		cmdpath = (path != pathval());
+		listsetvar(varlist.list, VEXPORT|VSTACK);
+		shellexec(argv[0], argv, cmdpath ? path : pathval(), cmdentry.u.index);
 #else
 		if (!(flags & EV_EXIT) || may_have_traps) {
 			/* No, forking off a child is necessary */
@@ -10798,9 +10811,9 @@ evalcommand(union node *cmd, int flags)
 			FORCE_INT_ON;
 			/* fall through to exec'ing external program */
 		}
-#endif
 		listsetvar(varlist.list, VEXPORT|VSTACK);
 		shellexec(argv[0], argv, path, cmdentry.u.index);
+#endif
 		/* NOTREACHED */
 	} /* default */
 	case CMDBUILTIN:
-- 
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