From 23fc1ecab1b49e3dfd681882946c6729adb78da6 Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Mon, 29 May 2023 11:20:58 -0500
Subject: [PATCH] Fix escape passthrough bug reported by Mingliang Hu.

---
 tests/sh.test     | 1 +
 toys/pending/sh.c | 8 ++++----
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/tests/sh.test b/tests/sh.test
index e435d26d..9e39c3d0 100644
--- a/tests/sh.test
+++ b/tests/sh.test
@@ -127,6 +127,7 @@ testing 'return code 3' 'x=0; while [ $((x++)) -lt 2 ]; do echo $x; done; echo $
 testing 'local var +whiteout' \
   'l=X;x(){ local l=47; echo $l;unset l; echo l=$l;};x;echo $l' '47\nl=\nX\n' \
   '' ''
+testing 'escape passthrough' 'echo -e "a\nb\nc\td"' 'a\nb\nc\td\n' '' ''
 
 testing 'trailing $ is literal' 'echo $' '$\n' '' ''
 # TODO testing 'empty +() is literal' 'echo +()' '+()\n' '' ''
diff --git a/toys/pending/sh.c b/toys/pending/sh.c
index ed2b6912..36f183b8 100644
--- a/toys/pending/sh.c
+++ b/toys/pending/sh.c
@@ -1903,13 +1903,13 @@ static int expand_arg_nobrace(struct sh_arg *arg, char *str, unsigned flags,
           for (kk = strlen(ifs); kk && ifs[kk-1]=='\n'; ifs[--kk] = 0);
         close(jj);
       }
-    } else if (cc=='\\' || !str[ii]) {
-      if (!(qq&1) || (str[ii] && strchr("\"\\$`", str[ii])))
-        new[oo++] = str[ii] ? str[ii++] : cc;
+    } else if (!str[ii]) new[oo++] = cc;
+    else if (cc=='\\')
+      new[oo++] = (!(qq&1) || strchr("\"\\$`", str[ii])) ? str[ii++] : cc;
 
     // $VARIABLE expansions
 
-    } else if (cc == '$' && str[ii]) {
+    else if (cc == '$') {
       cc = *(ss = str+ii++);
       if (cc=='\'') {
         for (s = str+ii; *s != '\''; oo += wcrtomb(new+oo, unescape2(&s, 0),0));
-- 
2.39.2