1 files changed, 57 insertions, 0 deletions
diff --git a/utils.c b/utils.c
new file mode 100644
index 0000000..1444894
--- /dev/null
+++ b/utils.c
@@ -0,0 +1,57 @@
+//
+// utils.c
+// Copyright 2021 Bruce Hill
+// Released under the MIT license with the Commons Clause
+//
+// This file contains implementations of some convenience functions for more
+// easily error checking.
+//
+
+#include <err.h>
+#include <stdarg.h>
+#include <stdlib.h>
+
+//
+// If the given argument is nonnegative, print the error message and exit with
+// failure. Otherwise, return the given argument.
+//
+int check_nonnegative(int negative_err, const char *err_msg, ...)
+{
+    if (negative_err < 0) {
+        va_list args;
+        va_start(args, err_msg);
+        verr(EXIT_FAILURE, err_msg, args);
+        va_end(args);
+    }
+    return negative_err;
+}
+
+//
+// If the given argument is NULL, print the error message and exit with
+// failure. Otherwise return the given argument.
+//
+void *check_nonnull(void *p, const char *err_msg, ...)
+{
+    if (p == NULL) {
+        va_list args;
+        va_start(args, err_msg);
+        verr(EXIT_FAILURE, err_msg, args);
+        va_end(args);
+    }
+    return p;
+}
+
+//
+// For a given pointer to a memory-allocated pointer, free its memory and set
+// the pointer to NULL. (This is a safer alternative to free() that
+// automatically NULLs out the pointer so it can't be used after freeing)
+//
+void delete(void *p)
+{
+    if (*(void**)p != NULL) {
+        free(*(void**)p);
+        *(void**)p = NULL;
+    }
+}
+
+// vim: ts=4 sw=0 et cino=L2,l1,(0,W4,m1