drivers/main.c, docs, etc.: accept "LIBUSB_DEBUG=NUM" setting via ups…

….conf

Signed-off-by: Jim Klimov <jimklimov+nut@gmail.com>

NEWS.adoc

@@ -191,6 +191,11 @@ https://github.com/networkupstools/nut/milestone/11
    of an UPS interface on a composite USB device or when looking at devices
    with non-default interface/endpoint/config numbers. [PR #2611]
 
+ - USB drivers should now accept a `LIBUSB_DEBUG=INTEGER` setting in `ups.conf`
+   (as well as an environment variable that can be generally set via `nut.conf`
+   or service unit methods or init script), to enable troubleshooting of LibUSB
+   itself. [issue #2616]
+
  - Introduced a new driver concept for interaction with OS-reported hardware
    monitoring readings. Currently instantiated as `hwmon_ina219` specifically
    made for Texas Instruments INA219 chip as exposed in the Linux "hwmon"

conf/ups.conf.sample

@@ -82,8 +82,8 @@
 # Set maxretry to 3 by default, this should mitigate race with slow devices:
 maxretry = 3
 
-# These directives can be set outside and inside a driver definition, with
-# slightly different meanings per context:
+# These directives can be set outside and inside a driver definition,
+# sometimes with slightly different meanings per context:
 #
 # maxstartdelay: OPTIONAL.  This can be set as a global variable
 #                above your first UPS definition and it can also be
@@ -111,6 +111,13 @@ maxretry = 3
 #              `debug_min` are set, the driver-level setting takes precedence.
 #              Command-line option `-D` can only increase this verbosity level.
 #
+# LIBUSB_DEBUG: OPTIONAL.  For run-time troubleshooting of USB-capable NUT
+#                drivers, you can specify the verbosity of LibUSB specific
+#                debugging as a numeric value such as `4` ("All messages
+#                are emitted").  Should not have any practical impact on
+#                other NUT drivers. For more details, see the library's
+#                documentation at e.g. https://libusb.sourceforge.io/api-1.0/
+#
 # user, group: OPTIONAL. Overrides the compiled-in (also global-section,
 #                when used in driver section) default unprivileged user/group
 #                name for NUT device driver. Impacts access rights used for

docs/man/nut_usb_addvars.txt

@@ -125,18 +125,21 @@ As a rule of thumb for `usb_hid_desc_index` discovery, you can see larger
 `wDescriptorLength` values (roughly 600+ bytes) in reports of `lsusb` or
 similar tools.
 
-[NOTE]
-======
+*LIBUSB_DEBUG =* 'INTEGER'::
+
 Run-time troubleshooting of USB-capable NUT drivers can involve not only
 raising the common NUT debug verbosity (e.g. using the `DEBUG_MIN` setting
 in linkman:ups.conf[5] or protocol commands to change the `driver.debug`
 value), but may also benefit from LibUSB specific debugging.
-
-For the latter, currently you would have to export the environment variable
-`LIBUSB_DEBUG` before starting a NUT driver (may be set and "exported" via
-linkman:nut.conf[5]), to a numeric value such as `4` ("All messages are
-emitted"). For more details, including the currently supported values, see:
++
+For the latter, you can set the `LIBUSB_DEBUG` driver option; alternatively
+you can classically export the environment variable `LIBUSB_DEBUG` before
+starting a NUT driver program (may be set and "exported" in driver init
+script or service method, perhaps via linkman:nut.conf[5]), to a numeric
+value such as `4` ("All messages are emitted").
++
+For more details, including the currently supported values for your version
+of the library, see e.g.:
 
 * https://libusb.sourceforge.io/api-1.0/
 * https://libusb.sourceforge.io/api-1.0/group__libusb__lib.html
-======

docs/man/ups.conf.txt

@@ -156,6 +156,19 @@ troubleshooting a deployment, without impacting foreground or background
 running mode directly. Command-line option `-D` can only increase this
 verbosity level.
 
+*LIBUSB_DEBUG* 'INTEGER'::
+
+Optional.  For run-time troubleshooting of USB-capable NUT drivers,
+you can specify verbosity of LibUSB specific debugging as a numeric
+value such as `4` ("All messages are emitted").  Should not have any
+practical impact on other NUT drivers.
++
+For more details, including the currently supported values for your
+version of the library, see e.g.:
+
+* https://libusb.sourceforge.io/api-1.0/
+* https://libusb.sourceforge.io/api-1.0/group__libusb__lib.html
+
 UPS FIELDS
 ----------
 
@@ -325,6 +338,18 @@ running mode directly.  If the global `debug_min` is also set, this
 driver-level setting overrides it.  Command-line option `-D` can only
 increase this verbosity level.
 
+*LIBUSB_DEBUG* 'INTEGER'::
+
+Optional.  For run-time troubleshooting of USB-capable NUT drivers,
+you can specify verbosity of LibUSB specific debugging as a numeric
+value such as `4` ("All messages are emitted").
++
+For more details, including the currently supported values for your
+version of the library, see e.g.:
+
+* https://libusb.sourceforge.io/api-1.0/
+* https://libusb.sourceforge.io/api-1.0/group__libusb__lib.html
+
 INTEGRATION
 -----------
 

drivers/main.c

@@ -1074,6 +1074,28 @@ static int main_arg(char *var, char *val)
 		return 1;	/* handled */
 	}
 
+	if (!strcmp(var, "LIBUSB_DEBUG")) {
+		int lvl = -1; /* https://libusb.sourceforge.io/api-1.0/group__libusb__lib.html#ga2d6144203f0fc6d373677f6e2e89d2d2 */
+		int msglvl = 1;
+		char buf[SMALLBUF], *s = getenv("LIBUSB_DEBUG");
+
+		if (!str_to_int(val, &lvl, 10) || lvl < 0) {
+			lvl = 4;
+			upslogx(LOG_INFO, "WARNING : Invalid LIBUSB_DEBUG value found in ups.conf for the driver, defaulting to %d", lvl);
+		}
+		if (nut_debug_level < 1 && nut_debug_level_driver < 1 && nut_debug_level_global < 1)
+			msglvl = 0;
+
+		if (s)
+			upsdebugx(msglvl, "Old value of LIBUSB_DEBUG=%s in envvars", s);
+
+		snprintf(buf, sizeof(buf), "%d", lvl);
+		upsdebugx(msglvl, "Enabling LIBUSB_DEBUG=%s from ups.conf", buf);
+		setenv("LIBUSB_DEBUG", buf, 1);
+
+		return 1;	/* handled */
+	}
+
 	return 0;	/* unhandled, pass it through to the driver */
 }
 
@@ -1200,6 +1222,28 @@ static void do_global_args(const char *var, const char *val)
 		return;
 	}
 
+	if (!strcmp(var, "LIBUSB_DEBUG")) {
+		int lvl = -1; /* https://libusb.sourceforge.io/api-1.0/group__libusb__lib.html#ga2d6144203f0fc6d373677f6e2e89d2d2 */
+		int msglvl = 1;
+		char buf[SMALLBUF], *s = getenv("LIBUSB_DEBUG");
+
+		if (!str_to_int(val, &lvl, 10) || lvl < 0) {
+			lvl = 4;
+			upslogx(LOG_INFO, "WARNING : Invalid LIBUSB_DEBUG value found in ups.conf for the driver, defaulting to %d", lvl);
+		}
+		if (nut_debug_level < 1 && nut_debug_level_driver < 1 && nut_debug_level_global < 1)
+			msglvl = 0;
+
+		if (s)
+			upsdebugx(msglvl, "Old value of LIBUSB_DEBUG=%s in envvars", s);
+
+		snprintf(buf, sizeof(buf), "%d", lvl);
+		upsdebugx(msglvl, "Enabling LIBUSB_DEBUG=%s from ups.conf", buf);
+		setenv("LIBUSB_DEBUG", buf, 1);
+
+		return;
+	}
+
 	/* unrecognized */
 }
 

include/nutconf.hpp

@@ -1667,6 +1667,7 @@ class UpsConfiguration : public GenericConfiguration
 	inline bool getNoWait()            const { return getFlag("nowait"); }
 
 	inline long long int getDebugMin()      const { return getInt("debug_min"); }
+	inline long long int getLibusbDebug()   const { return getInt("LIBUSB_DEBUG"); }
 	inline long long int getMaxRetry()      const { return getInt("maxretry"); }
 	inline long long int getMaxStartDelay() const { return getInt("maxstartdelay"); }
 	inline long long int getPollInterval()  const { return getInt("pollinterval", 5); }  // TODO: check the default
@@ -1681,6 +1682,7 @@ class UpsConfiguration : public GenericConfiguration
 	inline void setNoWait(bool val = true)              { setFlag("nowait",    val); }
 
 	inline void setDebugMin(long long int num)          { setInt("debug_min",     num); }
+	inline void setLibusbDebug(long long int num)       { setInt("LIBUSB_DEBUG",  num); }
 	inline void setMaxRetry(long long int num)          { setInt("maxretry",      num); }
 	inline void setMaxStartDelay(long long int delay)   { setInt("maxstartdelay", delay); }
 	inline void setPollInterval(long long int interval) { setInt("pollinterval",  interval); }
@@ -1848,6 +1850,7 @@ class UpsConfiguration : public GenericConfiguration
 	inline long long int getDaysOff(const std::string & ups)                   const { return getInt(ups, "daysoff"); }             // CHECKME
 	inline long long int getDaySweek(const std::string & ups)                  const { return getInt(ups, "daysweek"); }            // CHECKME
 	inline long long int getDebugMin(const std::string & ups)                  const { return getInt(ups, "debug_min"); }
+	inline long long int getLibusbDebug(const std::string & ups)               const { return getInt(ups, "LIBUSB_DEBUG"); }
 	inline long long int getFrequency(const std::string & ups)                 const { return getInt(ups, "frequency"); }           // CHECKME
 	inline long long int getHourOff(const std::string & ups)                   const { return getInt(ups, "houroff"); }             // CHECKME
 	inline long long int getHourOn(const std::string & ups)                    const { return getInt(ups, "houron"); }              // CHECKME
@@ -2061,6 +2064,7 @@ class UpsConfiguration : public GenericConfiguration
 	inline void setDaysOff(const std::string & ups, long long int daysoff)                    { setInt(ups, "daysoff",             daysoff); }      // CHECKME
 	inline void setDaysWeek(const std::string & ups, long long int daysweek)                  { setInt(ups, "daysweek",            daysweek); }     // CHECKME
 	inline void setDebugMin(const std::string & ups, long long int val)                       { setInt(ups, "debug_min",           val); }
+	inline void setLibusbDebug(const std::string & ups, long long int val)                    { setInt(ups, "LIBUSB_DEBUG",        val); }
 	inline void setFrequency(const std::string & ups, long long int frequency)                { setInt(ups, "frequency",           frequency); }    // CHECKME
 	inline void setHourOff(const std::string & ups, long long int houroff)                    { setInt(ups, "houroff",             houroff); }      // CHECKME
 	inline void setHourOn(const std::string & ups, long long int houron)                      { setInt(ups, "houron",              houron); }       // CHECKME