[settings] Allow numeric_setting_value() to handle long setting values

Allow numeric_setting_value() to handle e.g. the byte sequence

  00:00:00:00:12:34:56:78

by returning -ERANGE only if the value actually overflows the return
type.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/settings.c

 	const int8_t *signed_bytes = raw;
 	int is_negative;
 	unsigned int i;
+	uint8_t pad;
 	uint8_t byte;
 
-	/* Range check */
-	if ( len > sizeof ( long ) )
-		return -ERANGE;
-
 	/* Convert to host-ordered longs */
 	is_negative = ( len && ( signed_bytes[0] < 0 ) );
 	*value = ( ( is_signed && is_negative ) ? -1L : 0 );
+	pad = *value;
 	for ( i = 0 ; i < len ; i++ ) {
 		byte = unsigned_bytes[i];
 		*value = ( ( *value << 8 ) | byte );
+		if ( ( ( i + sizeof ( *value ) ) < len ) && ( byte != pad ) )
+			return -ERANGE;
 	}
 
 	return len;

src/tests/settings_test.c

 		    RAW ( 0x98, 0xab, 0x41, 0x81 ), 0x98ab4181 );
 	fetchn_ok ( &test_settings, &test_uint32_setting,
 		    RAW ( 0xff, 0xff, 0xfe ), 0x00fffffe );
+	fetchn_ok ( &test_settings, &test_uint32_setting,
+		    RAW ( 0, 0, 0, 0x12, 0x34, 0x56, 0x78 ), 0x12345678 );
+	fetchn_ok ( &test_settings, &test_int32_setting,
+		    RAW ( 0, 0, 0, 0x12, 0x34, 0x56, 0x78 ), 0x12345678 );
+	fetchn_ok ( &test_settings, &test_int32_setting,
+		    RAW ( 0xff, 0xff, 0x87, 0x65, 0x43, 0x21 ), -0x789abcdf );
 
 	/* "hex" setting type */
 	storef_ok ( &test_settings, &test_hex_setting,