Add original unix v6

source/s5/perror.c

@@ -0,0 +1,40 @@
+/*
+ * Print the error indicated
+ * in the cerror cell.
+ */
+
+int	errno;
+int	sys_nerr;
+char	*sys_errlist[];
+perror(s)
+char *s;
+{
+	register char *c;
+	register n;
+
+	c = "Unknown error";
+	if(errno < sys_nerr)
+		c = sys_errlist[errno];
+	n = strlen(s);
+	if(n) {
+		write(2, s, n);
+		write(2, ": ", 2);
+	}
+	write(2, c, strlen(c));
+	write(2, "\n", 1);
+}
+
+/*
+ * Return the number of bytes in a string
+ */
+
+strlen(str)
+char *str;
+{
+	register char *s;
+
+	s = str;
+	while(*s++)
+		;
+	return(s-str-1);
+}