opt: Predicates aren't true when they're false

This unfortunate typo was mostly harmless; since the predicates were
always assumed to be true, they wouldn't conflict.  The exception is
-user/-group, which set -nouser/-nogroup to false for users/groups that
exist.

Even -O0 wasn't enough to suppress the bug, due to a missing optlevel
check fixed in the previous commit.

Fixes: 305ee902874b49351f4916e303c293523f11570b

2 files changed, 14 insertions, 2 deletions

diff --git a/opt.c b/opt.c
index 8c516ea..50ad212 100644
--- a/opt.c
+++ b/opt.c
@@ -1,6 +1,6 @@
 /****************************************************************************
  * bfs                                                                      *
- * Copyright (C) 2017-2019 Tavian Barnes <tavianator@tavianator.com>        *
+ * Copyright (C) 2017-2020 Tavian Barnes <tavianator@tavianator.com>        *
  *                                                                          *
  * Permission to use, copy, modify, and/or distribute this software for any *
  * purpose with or without fee is hereby granted.                           *
@@ -712,7 +712,7 @@ fail:
 /** Infer data flow facts about a predicate. */
 static void infer_pred_facts(struct opt_state *state, enum pred_type pred) {
 	constrain_pred(&state->facts_when_true.preds[pred], true);
-	constrain_pred(&state->facts_when_false.preds[pred], true);
+	constrain_pred(&state->facts_when_false.preds[pred], false);
 }
 
 /** Infer data flow facts about an -{execut,read,writ}able expression. */
diff --git a/tests.sh b/tests.sh
index 7276672..673e155 100755
--- a/tests.sh
+++ b/tests.sh
@@ -196,6 +196,7 @@ posix_tests=(
 
     test_group_name
     test_group_id
+    test_group_nogroup
 
     test_links
     test_links_plus
@@ -244,6 +245,7 @@ posix_tests=(
 
     test_user_name
     test_user_id
+    test_user_nouser
 
     # Closed file descriptors
     test_closed_stdin
@@ -1376,6 +1378,11 @@ function test_user_id() {
     bfs_diff basic -user "$(id -u)"
 }
 
+function test_user_nouser() {
+    # Regression test: this was wrongly optimized to -false
+    bfs_diff basic -user "$(id -u)" \! -nouser
+}
+
 function test_group_name() {
     bfs_diff basic -group "$(id -gn)"
 }
@@ -1384,6 +1391,11 @@ function test_group_id() {
     bfs_diff basic -group "$(id -g)"
 }
 
+function test_group_nogroup() {
+    # Regression test: this was wrongly optimized to -false
+    bfs_diff basic -group "$(id -g)" \! -nogroup
+}
+
 function test_daystart() {
     bfs_diff basic -daystart -mtime 0
 }