From e76971b0a7919f13ce9c5eb4b194f93d8c8a9645 Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Wed, 12 Aug 2026 15:16:32 -0500
Subject: [PATCH] Fix prefix assignment in pipelines.

---
 tests/sh.test     | 6 ++++++
 toys/pending/sh.c | 9 ++++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/tests/sh.test b/tests/sh.test
index 7225fa2d..ce1fa6de 100644
--- a/tests/sh.test
+++ b/tests/sh.test
@@ -170,6 +170,12 @@ testing 'assignment with not is persistent' '! a=b; echo $a $?' 'b 1\n' '' ''
 testing '! ! redirect prefix assignment exported not persistent' \
   '! ! > file.txt A=B env; echo $?; grep ^A= file.txt; echo $A' \
   '0\nA=B\n\n' '' ''
+testing 'prefix assignment pipe-local' 'ABC=abc; ABC=def true | echo $ABC' \
+  'abc\n' '' ''
+testing 'prefix assignment exports' \
+  'ABC=abc; ABC=def env | grep ^ABC=; echo $ABC' 'ABC=def\nabc\n' '' ''
+testing 'redundant prefix assignment' \
+  'ABC=abc; ABC=def ABC=ghi env | grep ^ABC=; echo $ABC' 'ABC=ghi\nabc\n' '' ''
 
 $BROKEN testing '$_ with functions' 'true; x(){ echo $_;}; x abc; echo $_' \
   'true\nabc\n' '' ''
diff --git a/toys/pending/sh.c b/toys/pending/sh.c
index 1c3de708..25ac85af 100644
--- a/toys/pending/sh.c
+++ b/toys/pending/sh.c
@@ -1041,6 +1041,7 @@ bad:
 static struct sh_vars *setvar_long(char *s, int freeable, struct sh_fcall *ff)
 {
   struct sh_vars *vv = 0, *was;
+  struct sh_fcall *new;
   char *ss;
 
   if (!s) return 0;
@@ -1053,7 +1054,9 @@ static struct sh_vars *setvar_long(char *s, int freeable, struct sh_fcall *ff)
   }
 
   // Add if necessary, set value, and remove again if we added but set failed
-  if (!(was = vv = findvar(s, &ff))) (vv = addvar(s, ff))->flags = VAR_NOFREE;
+  if (!(was = vv = findvar(s, &new)) || (ff && new!=ff))
+    (vv = addvar(s, ff = ff ? : TT.ff->prev))->flags = VAR_NOFREE;
+  else ff = new;
   if (!setvar_found(s, freeable, vv)) {
     if (!was) memmove(vv, vv+1, sizeof(struct sh_vars)*(ff->varslen-- -(vv-ff->vars)));
 
@@ -1068,7 +1071,7 @@ static struct sh_vars *setvar_long(char *s, int freeable, struct sh_fcall *ff)
 // Returns sh_vars * or 0 for failure (readonly, etc)
 static struct sh_vars *setvar(char *str)
 {
-  return setvar_long(str, 1, TT.ff->prev);
+  return setvar_long(str, 1, 0);
 }
 
 
@@ -2999,7 +3002,7 @@ static struct sh_process *run_command(int local)
 
     if ((ss = expand_one_arg(s = prefix.v[jj], NO_IFS))) {
       if (!local && ss==s) ss = xstrdup(ss);
-      if ((vv = setvar_long(ss, ss!=s, local ? TT.ff : TT.ff->prev)))
+      if ((vv = setvar_long(ss, ss!=s, local ? TT.ff : 0)))
         if (local) vv->flags |= VAR_EXPORT;
     } else pp->exit = 1;
   }
-- 
2.39.5