From 08d1ff5df0047be7012875ca88cc64e4f205b7c3 Mon Sep 17 00:00:00 2001
From: "Mark Landis (N6AZX)" <n6azx@fastmail.com>
Date: Tue, 27 Dec 2022 15:04:09 -0800
Subject: [PATCH] isdigit() may return any non-zero result for success

POSIX states that the return value of isdigit(): "shall return non-zero
if c is a decimal digit; otherwise, they shall return 0."

Thus the form:

  ok &= isdigit(x)

is invalid since the runtime is not required to return 1.

This bug was observed on Debian 11 while using the clang toolchain.
In that environment, isdigit() returns 2048 for a positive match.
---
 src/cdmriddir.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/cdmriddir.cpp b/src/cdmriddir.cpp
index 5d62db3..efad32f 100644
--- a/src/cdmriddir.cpp
+++ b/src/cdmriddir.cpp
@@ -152,7 +152,7 @@ bool CDmridDir::IsValidDmrid(const char *sz)
         ok = true;
         for ( size_t i = 0; (i < n) && ok; i++ )
         {
-            ok &= ::isdigit(sz[i]);
+            ok = ::isdigit(sz[i]);
         }
     }
     return ok;