Merge pull request #2400 from jimklimov/issue-2399

drivers/libusb{0,1}.c, NEWS.adoc: avoid spurious syslog of `(nut_)libusb_get_string: Success`

Author: jimklimov

NEWS.adoc

@@ -59,6 +59,10 @@ https://github.com/networkupstools/nut/milestone/11
      (similar to `runtimecal` in some other drivers, may be refactored
      to that configuration and logic model in later NUT releases)
 
+ - USB drivers could log `(nut_)libusb_get_string: Success` due to either
+   reading an empty string or getting a success code `0` from libusb.
+   This difference should now be better logged, and not into syslog. [#2399]
+
  - upsmon: it was realized that the `POWERDOWNFLAG` must be explicitly set in
    the configuration file, there is no built-in default in the binary program
    (the settings facilitated by the `configure` script during build "only"

drivers/libusb0.c

@@ -5,6 +5,7 @@
  * @author Copyright (C)
  *  2003 - 2007 Arnaud Quette <[email protected]>
  *  2005 - 2007 Peter Selinger <[email protected]>
+ *  2021 - 2024 Jim Klimov <[email protected]>
  *
  * This program is sponsored by MGE UPS SYSTEMS - opensource.mgeups.com
  *
@@ -37,7 +38,7 @@
 #endif
 
 #define USB_DRIVER_NAME		"USB communication driver (libusb 0.1)"
-#define USB_DRIVER_VERSION	"0.47"
+#define USB_DRIVER_VERSION	"0.48"
 
 /* driver description structure */
 upsdrv_info_t comm_upsdrv_info = {
@@ -781,6 +782,7 @@ static int libusb_strerror(const int ret, const char *desc)
 		return 0;
 #endif	/* WIN32 */
 
+	case 0: 	/** TOTHINK: Should this (probably LIBUSB_SUCCESS) be quiet? */
 	default:	/* Undetermined, log only */
 		upslogx(LOG_DEBUG, "%s: %s", desc, usb_strerror());
 		return 0;
@@ -907,6 +909,18 @@ static int libusb_get_string(
 	errno = -ret;
 #endif
 
+	/** 0 can be seen as an empty string, or as a success for
+	 * logging below - also tends to happen */
+	if (ret == 0) {
+		size_t len = strlen(buf);
+		upsdebugx(2, "%s: usb_get_string_simple() returned "
+			"0 (might be just success code), "
+			"actual buf length is %" PRIuSIZE, __func__, len);
+		/* if (len) */
+			return len;
+		/* else may log "libusb_get_string: Success" and return 0 below */
+	}
+
 	return libusb_strerror(ret, __func__);
 }
 

drivers/libusb1.c

@@ -4,7 +4,7 @@
  *
  * @author Copyright (C) 2016 Eaton
  *         Copyright (C) 2016 Arnaud Quette <[email protected]>
- *         Copyright (C) 2021 Jim Klimov <[email protected]>
+ *         Copyright (C) 2021-2024 Jim Klimov <[email protected]>
  *
  *      The logic of this file is ripped from mge-shut driver (also from
  *      Arnaud Quette), which is a "HID over serial link" UPS driver for
@@ -33,7 +33,7 @@
 #include "nut_stdint.h"
 
 #define USB_DRIVER_NAME		"USB communication driver (libusb 1.0)"
-#define USB_DRIVER_VERSION	"0.47"
+#define USB_DRIVER_VERSION	"0.48"
 
 /* driver description structure */
 upsdrv_info_t comm_upsdrv_info = {
@@ -872,6 +872,7 @@ static int nut_libusb_strerror(const int ret, const char *desc)
 		return 0;
 #endif /* WIN32 */
 
+	case LIBUSB_SUCCESS:         /** TOTHINK: Should this be quiet? */
 	case LIBUSB_ERROR_OTHER:     /** Other error */
 	default:                     /** Undetermined, log only */
 		upslogx(LOG_DEBUG, "%s: %s", desc, libusb_strerror((enum libusb_error)ret));
@@ -1022,6 +1023,18 @@ static int nut_libusb_get_string(
 	ret = libusb_get_string_descriptor_ascii(udev, (uint8_t)StringIdx,
 		(unsigned char*)buf, (int)buflen);
 
+	/** 0 can be seen as an empty string, or as LIBUSB_SUCCESS for
+	 * logging below - also tends to happen */
+	if (ret == 0) {
+		size_t len = strlen(buf);
+		upsdebugx(2, "%s: libusb_get_string_descriptor_ascii() returned "
+			"0 (might be just LIBUSB_SUCCESS code), "
+			"actual buf length is %" PRIuSIZE, __func__, len);
+		/* if (len) */
+			return len;
+		/* else may log "nut_libusb_get_string: Success" and return 0 below */
+	}
+
 	return nut_libusb_strerror(ret, __func__);
 }