add dupeString wrapper function

This function calls strdup and exits on failure.

src/stringhandling.c

@@ -62,6 +62,17 @@ void *reallocMem(void *p, size_t n)
 	return s;
 }
 
+char *dupeString(char *s)
+{
+	char *c;
+
+	if (!(c = strdup(s))) {
+		fprintf(stderr, "Out of memory!\n");
+		exit(1);
+	}
+	return c;
+}
+
 char *initString(int *l)
 {
 	*l = 0;

src/stringhandling.h

@@ -26,6 +26,7 @@ extern char *EMPTYSTRING;
 
 void *allocMem(size_t n);
 void *reallocMem(void *p, size_t n);
+char *dupeString(char *s);
 char *initString(int *l);
 void stringAndString(char **s, int *l, const char *t);
 void stringAndBytes(char **s, int *l, const char *t, int cnt);