new file mode 100644
--- /dev/null
+++ b/src/os/unix/ngx_errno.c
@@ -0,0 +1,24 @@
+#include <ngx_config.h>
+#include <ngx_core.h>
+
+
+ngx_int_t ngx_strerror_r(int err, char *errstr, size_t size)
+{
+    size_t  len;
+
+    if (size == 0) {
+        return 0;
+    }
+
+    errstr[0] = '\0';
+
+    strerror_r(err, errstr, size);
+
+    for (len = 0; len < size; len++) {
+        if (errstr[len] == '\0') {
+            break;
+        }
+    }
+
+    return len;
+}