Port and use a variant of nut_usb_get_string() for nut-scanner

NEWS.adoc

@@ -166,9 +166,11 @@ https://github.com/networkupstools/nut/milestone/11
    * Currently this was tested to fix certain device discovery with `usbhid-ups`;
      should also apply out of the box to same discovery logic in `blazer_usb`,
      `nutdrv_qx`, `riello_usb` and `tripplite_usb` drivers.
+   * Also applied to `nut-scanner` and `libnutscan`. [issue #2615]
    * More work may be needed for other USB-capable drivers (`richcomm_usb`,
      `nutdrv_atcl_usb`) and for general code to collect string readings and
-     other data points, and for `nut-scanner`.
+     other data points, and to configure the fallback locale or choose one
+     if several are served by the device. [issues #2613, #2614, #2615]
 
  - Introduced a new driver concept for interaction with OS-reported hardware
    monitoring readings. Currently instantiated as `hwmon_ina219` specifically

drivers/usb-common.c

@@ -416,7 +416,10 @@ void warn_if_bad_usb_port_filename(const char *fn) {
  */
 #define MAX_STRING_DESC_TRIES 3
 
-/* API neutral, handles retries */
+/* API neutral, handles retries.
+ * Note for future development: a variant of this code is adapted into
+ * tools/nut-scanner/scan_usb.c - please keep in sync if changing here.
+ */
 static int nut_usb_get_string_descriptor(
 	usb_dev_handle *udev,
 	int StringIdx,
@@ -433,13 +436,16 @@ static int nut_usb_get_string_descriptor(
 			break;
 		} else if (tries) {
 			upsdebugx(1, "%s: string descriptor %d request failed, retrying...", __func__, StringIdx);
-			usleep(50000); /* 50 ms, might help in some cases */
+			usleep(50000);	/* 50 ms, might help in some cases */
 		}
 	}
 	return ret;
 }
 
-/* API neutral, assumes en_US if langid descriptor is broken */
+/* API neutral, assumes en_US if langid descriptor is broken.
+ * Note for future development: a variant of this code is adapted into
+ * tools/nut-scanner/scan_usb.c - please keep in sync if changing here.
+ */
 int nut_usb_get_string(
 	usb_dev_handle *udev,
 	int StringIdx,
@@ -480,13 +486,13 @@ int nut_usb_get_string(
 
 	/* translate simple UTF-16LE to 8-bit */
 	len = ret < (int)buflen ? ret : (int)buflen;
-	len = len / 2 - 1; // 16-bit characters, without header
-	len = len < (int)buflen - 1 ? len : (int)buflen - 1; // reserve for null terminator
+	len = len / 2 - 1;	/* 16-bit characters, without header */
+	len = len < (int)buflen - 1 ? len : (int)buflen - 1;	/* reserve for null terminator */
 	for (i = 0; i < len; i++) {
 		if (buffer[2 + i * 2 + 1] == 0)
 			buf[i] = buffer[2 + i * 2];
 		else
-			buf[i] = '?'; // not decoded
+			buf[i] = '?';	/* not decoded */
 	}
 	buf[i] = '\0';
 

m4/ax_realpath_lib.m4

@@ -156,25 +156,52 @@ AC_DEFUN([AX_REALPATH_LIB],
         AS_IF([test -n "${myLIBPATH}" && test -s "${myLIBPATH}"], [
             AC_MSG_RESULT([initially '${myLIBPATH}'])
 
-            dnl # Resolving the directory location is a nice bonus
-            dnl # (usually the paths are relative to toolkit and ugly,
-            dnl # though maybe arguably portable with regard to symlinks).
-            dnl # The primary goal is to resolve the actual library file
-            dnl # name like "libnetsnmp.so.1.2.3", so we can preferentially
-            dnl # try to dlopen() it on a system with a packaged footprint
-            dnl # that does not serve short (developer-friendly) links like
-            dnl # "libnetsnmp.so".
-            myLIBPATH_REAL="${myLIBPATH}"
-            AX_REALPATH([${myLIBPATH}], [myLIBPATH_REAL])
+            AC_MSG_CHECKING([whether the file is a "GNU ld script" and not a binary])
+            AS_IF([LANG=C LC_ALL=C file "${myLIBPATH}" | grep -Ei '(ascii|text)' && grep -w GROUP "${myLIBPATH}" >/dev/null], [
+                # dnl e.g. # cat /usr/lib/x86_64-linux-gnu/libusb.so
+                # dnl    /* GNU ld script.  */
+                # dnl    GROUP ( /lib/x86_64-linux-gnu/libusb-0.1.so.4.4.4 )
+                # dnl Note that spaces around parentheses vary, more keywords
+                # dnl may be present in a group (e.g. AS_NEEDED), and comment
+                # dnl strings are inconsistent (useless to match by).
+                AC_MSG_RESULT([yes, iterate further])
+                myLIBPATH_LDSCRIPT="`grep -w GROUP "${myLIBPATH}" | sed 's,^.*GROUP *( *\(/@<:@^ @:>@*\.so@<:@^ @:>@*\)@<:@^0-9a-zA-Z_.-@:>@.*$,\1,'`"
+                AS_IF([test -n "${myLIBPATH_LDSCRIPT}" && test -s "${myLIBPATH_LDSCRIPT}"], [
+                    AC_MSG_NOTICE([will dig into ${myLIBPATH_LDSCRIPT}])
+
+                    dnl # See detailed comments just below
+                    myLIBPATH_REAL="${myLIBPATH_LDSCRIPT}"
+                    AX_REALPATH([${myLIBPATH_LDSCRIPT}], [myLIBPATH_REAL])
+                ], [
+                    AC_MSG_NOTICE([could not determine a further path name, will use what we have])
+
+                    dnl # See detailed comments just below
+                    myLIBPATH_REAL="${myLIBPATH}"
+                    AX_REALPATH([${myLIBPATH}], [myLIBPATH_REAL])
+                ])
+            ],[
+                AC_MSG_RESULT([no, seems like a normal binary])
+
+                dnl # Resolving the directory location is a nice bonus
+                dnl # (usually the paths are relative to toolkit and ugly,
+                dnl # though maybe arguably portable with regard to symlinks).
+                dnl # The primary goal is to resolve the actual library file
+                dnl # name like "libnetsnmp.so.1.2.3", so we can preferentially
+                dnl # try to dlopen() it on a system with a packaged footprint
+                dnl # that does not serve short (developer-friendly) links like
+                dnl # "libnetsnmp.so".
+                myLIBPATH_REAL="${myLIBPATH}"
+                AX_REALPATH([${myLIBPATH}], [myLIBPATH_REAL])
+            ])
+
             AC_MSG_RESULT(${myLIBPATH_REAL})
             $2="${myLIBPATH_REAL}"
-            ],[
+        ],[
             AC_MSG_RESULT([not found])
             $2="$3"
-            ])
-        ],
-        [AC_MSG_WARN([Compiler not detected as GCC/CLANG-compatible, skipping REALPATH_LIB($1)])
-         $2="$3"
-        ]
-    )
+        ])
+    ],
+    [AC_MSG_WARN([Compiler not detected as GCC/CLANG-compatible, skipping REALPATH_LIB($1)])
+     $2="$3"
+    ])
 ])

tools/nut-scanner/scan_usb.c

@@ -43,9 +43,15 @@ static const char *dl_error = NULL;
 static char *dl_saved_libname = NULL;
 
 static int (*nut_usb_close)(libusb_device_handle *dev);
-static int (*nut_usb_get_string_simple)(libusb_device_handle *dev, int index,
+static int (*nut_usb_control_transfer)(libusb_device_handle *dev,
+		uint8_t request_type, uint8_t bRequest, uint16_t wValue, uint16_t wIndex,
+		unsigned char *data, uint16_t wLength, unsigned int timeout);
+static int (*nut_usb_get_string_with_langid)(libusb_device_handle *dev, int index, int langid,
+		char *buf, size_t buflen);
+/* Fallback implem if the above is not a library symbol */
+static int nut_usb_get_string_with_langid_control_transfer(
+		libusb_device_handle *dev, int index, int langid,
 		char *buf, size_t buflen);
-
 
 /* Compatibility layer between libusb 0.1 and 1.0 */
 #if WITH_LIBUSB_1_0
@@ -64,6 +70,9 @@ static int (*nut_usb_get_string_simple)(libusb_device_handle *dev, int index,
  static uint8_t (*nut_usb_get_port_number)(libusb_device *dev);
  static int (*nut_usb_get_device_descriptor)(libusb_device *dev,
 	struct libusb_device_descriptor *desc);
+# define USB_DT_STRING	LIBUSB_DT_STRING
+# define USB_ENDPOINT_IN	LIBUSB_ENDPOINT_IN
+# define USB_REQ_GET_DESCRIPTOR	LIBUSB_REQUEST_GET_DESCRIPTOR
 #else /* => WITH_LIBUSB_0_1 */
 # define USB_INIT_SYMBOL "usb_init"
 # define USB_OPEN_SYMBOL "usb_open"
@@ -196,11 +205,20 @@ int nutscan_load_usb_library(const char *libname_path)
 			goto err;
 	}
 
-	*(void **) (&nut_usb_get_string_simple) = lt_dlsym(dl_handle,
-					"libusb_get_string_descriptor_ascii");
+	*(void **) (&nut_usb_control_transfer) = lt_dlsym(dl_handle,
+					"libusb_control_transfer");
 	if ((dl_error = lt_dlerror()) != NULL) {
 			goto err;
 	}
+
+	*(void **) (&nut_usb_get_string_with_langid) = lt_dlsym(dl_handle,
+					"libusb_get_string_descriptor");
+	if ((dl_error = lt_dlerror()) != NULL) {
+			/* This one may be only defined in a header as an inline method;
+			 * then we are adapting it via nut_usb_control_transfer().
+			 */
+			nut_usb_get_string_with_langid = NULL;
+	}
 #else /* for libusb 0.1 */
 	*(void **) (&nut_usb_find_busses) = lt_dlsym(dl_handle,
 					"usb_find_busses");
@@ -228,12 +246,23 @@ int nutscan_load_usb_library(const char *libname_path)
 			goto err;
 	}
 
-	*(void **) (&nut_usb_get_string_simple) = lt_dlsym(dl_handle,
-					"usb_get_string_simple");
+	*(void **) (&nut_usb_control_transfer) = lt_dlsym(dl_handle,
+					"usb_control_msg");
 	if ((dl_error = lt_dlerror()) != NULL) {
 			goto err;
 	}
-#endif /* WITH_LIBUSB_1_0 */
+
+	*(void **) (&nut_usb_get_string_with_langid) = lt_dlsym(dl_handle,
+					"usb_get_string");
+	if ((dl_error = lt_dlerror()) != NULL) {
+			/* See comment above */
+			nut_usb_get_string_with_langid = NULL;
+	}
+#endif /* not WITH_LIBUSB_1_0 => for libusb 0.1 */
+
+	if (nut_usb_get_string_with_langid == NULL) {
+			nut_usb_get_string_with_langid = nut_usb_get_string_with_langid_control_transfer;
+	}
 
 	if (dl_saved_libname)
 		free(dl_saved_libname);
@@ -273,6 +302,107 @@ static char* is_usb_device_supported(usb_device_id_t *usb_device_id_list,
 	return NULL;
 }
 
+/* This one may be only defined in a header as an inline method;
+ * then we are adapting it via nut_usb_control_transfer() per
+ * https://github.com/libusb/libusb-compat-0.1/blob/eaed7b8f11badaf07a91e07538f6e8842f59eaab/libusb/libusb-dload.h#L165-L171
+ */
+static int nut_usb_get_string_with_langid_control_transfer(
+		libusb_device_handle *dev, int index, int langid,
+		char *buf, size_t buflen)
+{
+	return (*nut_usb_control_transfer)(
+		dev, USB_ENDPOINT_IN, USB_REQ_GET_DESCRIPTOR,
+		(USB_DT_STRING << 8) + index, langid,
+		(unsigned char *)buf, buflen, 1000);
+}
+
+/* Replicated from usb-common.c with consideration for nut-scanner's
+ * use of method pointers instead of direct linking. API neutral,
+ * handles retries. Retries were originally introduced for "Tripp Lite"
+ * devices, see https://github.com/networkupstools/nut/issues/414
+ */
+#define MAX_STRING_DESC_TRIES 3
+
+static int nut_usb_get_string_descriptor(
+	libusb_device_handle *udev,
+	int StringIdx,
+	int langid,
+	char *buf,
+	size_t buflen)
+{
+	int ret = -1;
+	int tries = MAX_STRING_DESC_TRIES;
+
+	while (tries--) {
+		ret = (*nut_usb_get_string_with_langid)(
+			udev, StringIdx,
+			langid, buf, buflen);
+		if (ret >= 0) {
+			break;
+		} else if (tries) {
+			upsdebugx(1, "%s: string descriptor %d request failed, retrying...", __func__, StringIdx);
+			usleep(50000);	/* 50 ms, might help in some cases */
+		}
+	}
+	return ret;
+}
+
+/* Replicated from usb-common.c with consideration for nut-scanner's
+ * use of method pointers instead of direct linking. API neutral,
+ * assumes en_US if langid descriptor is broken */
+static int nut_usb_get_string(
+	libusb_device_handle *udev,
+	int StringIdx,
+	char *buf,
+	size_t buflen)
+{
+	int ret;
+	char buffer[255];
+	int langid;
+	int len;
+	int i;
+
+	if (!udev || StringIdx < 1 || StringIdx > 255) {
+		return -1;
+	}
+
+	/* request langid descriptor */
+	ret = nut_usb_get_string_descriptor(udev, 0, 0, buffer, 4);
+	if (ret < 0)
+		return ret;
+
+	if (ret == 4 && buffer[0] >= 4 && buffer[1] == USB_DT_STRING) {
+		langid = buffer[2] | (buffer[3] << 8);
+	} else {
+		upsdebugx(1, "%s: Broken language identifier, assuming en_US", __func__);
+		langid = 0x0409;
+	}
+
+	/* retrieve string in preferred language */
+	ret = nut_usb_get_string_descriptor(udev, StringIdx, langid, buffer, sizeof(buffer));
+	if (ret < 0) {
+#ifdef WIN32
+		/* only for libusb0 ? */
+		errno = -ret;
+#endif
+		return ret;
+	}
+
+	/* translate simple UTF-16LE to 8-bit */
+	len = ret < (int)buflen ? ret : (int)buflen;
+	len = len / 2 - 1;	/* 16-bit characters, without header */
+	len = len < (int)buflen - 1 ? len : (int)buflen - 1;	/* reserve for null terminator */
+	for (i = 0; i < len; i++) {
+		if (buffer[2 + i * 2 + 1] == 0)
+			buf[i] = buffer[2 + i * 2];
+		else
+			buf[i] = '?';	/* not decoded */
+	}
+	buf[i] = '\0';
+
+	return len;
+}
+
 /* return NULL if error */
 nutscan_device_t * nutscan_scan_usb(nutscan_usb_t * scanopts)
 {
@@ -496,7 +626,7 @@ nutscan_device_t * nutscan_scan_usb(nutscan_usb_t * scanopts)
 
 				/* get serial number */
 				if (iSerialNumber) {
-					ret = (*nut_usb_get_string_simple)(udev,
+					ret = nut_usb_get_string(udev,
 						iSerialNumber, string, sizeof(string));
 					if (ret > 0) {
 						serialnumber = strdup(str_rtrim(string, ' '));
@@ -521,7 +651,7 @@ nutscan_device_t * nutscan_scan_usb(nutscan_usb_t * scanopts)
 
 				/* get product name */
 				if (iProduct) {
-					ret = (*nut_usb_get_string_simple)(udev,
+					ret = nut_usb_get_string(udev,
 						iProduct, string, sizeof(string));
 					if (ret > 0) {
 						device_name = strdup(str_rtrim(string, ' '));
@@ -547,7 +677,7 @@ nutscan_device_t * nutscan_scan_usb(nutscan_usb_t * scanopts)
 
 				/* get vendor name */
 				if (iManufacturer) {
-					ret = (*nut_usb_get_string_simple)(udev,
+					ret = nut_usb_get_string(udev,
 						iManufacturer, string, sizeof(string));
 					if (ret > 0) {
 						vendor_name = strdup(str_rtrim(string, ' '));