lsusb: Get manufacturer, product, and serial from sysfs

When running with -v, we previously populated these strings only if we
were able to open the device and query the string descriptors directly.
However, these three values are also reported by the kernel as
world-readable files in sysfs. By querying those instead (using the same
function that already existed for querying fallback vendor and product
names), we can populate these values even for unprivileged users.

These sysfs properties have existed since at least 2005, so I think it's
quite unlikely that this change will regress existing users. However, if
it turns out to, we can always add back the old logic as a fallback when
sysfs isn't available.

Signed-off-by: Thomas Hebb <tommyhebb@gmail.com>

1 files changed, 9 insertions, 10 deletions

diff --git a/lsusb.c b/lsusb.c
index 6a547fb..1d7c105 100644
--- a/lsusb.c
+++ b/lsusb.c
@@ -267,13 +267,14 @@ static void dump_junk(const unsigned char *buf, const char *indent, unsigned int
  */
 
 static void dump_device(
-	libusb_device_handle *dev,
+	libusb_device *dev,
 	struct libusb_device_descriptor *descriptor
 )
 {
 	char vendor[128], product[128];
 	char cls[128], subcls[128], proto[128];
-	char *mfg, *prod, *serial;
+	char mfg[128] = {0}, prod[128] = {0}, serial[128] = {0};
+	char sysfs_name[PATH_MAX];
 
 	get_vendor_string(vendor, sizeof(vendor), descriptor->idVendor);
 	get_product_string(product, sizeof(product),
@@ -284,9 +285,11 @@ static void dump_device(
 	get_protocol_string(proto, sizeof(proto), descriptor->bDeviceClass,
 			descriptor->bDeviceSubClass, descriptor->bDeviceProtocol);
 
-	mfg = get_dev_string(dev, descriptor->iManufacturer);
-	prod = get_dev_string(dev, descriptor->iProduct);
-	serial = get_dev_string(dev, descriptor->iSerialNumber);
+	if (get_sysfs_name(sysfs_name, sizeof(sysfs_name), dev) >= 0) {
+		read_sysfs_prop(mfg, sizeof(vendor), sysfs_name, "manufacturer");
+		read_sysfs_prop(prod, sizeof(vendor), sysfs_name, "product");
+		read_sysfs_prop(serial, sizeof(vendor), sysfs_name, "serial");
+	}
 
 	printf("Device Descriptor:\n"
 	       "  bLength             %5u\n"
@@ -315,10 +318,6 @@ static void dump_device(
 	       descriptor->iProduct, prod,
 	       descriptor->iSerialNumber, serial,
 	       descriptor->bNumConfigurations);
-
-	free(mfg);
-	free(prod);
-	free(serial);
 }
 
 static void dump_wire_adapter(const unsigned char *buf)
@@ -3618,7 +3617,7 @@ static void dumpdev(libusb_device *dev)
 	}
 
 	libusb_get_device_descriptor(dev, &desc);
-	dump_device(udev, &desc);
+	dump_device(dev, &desc);
 	if (desc.bcdUSB == 0x0250)
 		wireless = do_wireless(udev);
 	if (desc.bNumConfigurations) {