coccinelle: check for invalid errno comparisons

Prompted by #15868

diff --git a/coccinelle/errno-check.cocci b/coccinelle/errno-check.cocci
new file mode 100644 (file)
index 0000000..709cb4a
--- /dev/null
+++ b/coccinelle/errno-check.cocci
@@ -0,0 +1,10 @@
+@@
+constant c;
+@@
+(
+- errno == -c
++ errno == c
+|
+- errno != -c
++ errno != c
+)