Linux: Search for /dev/usbdev<bus>.<device> USB device special files

If neither the (now deprecated) usbfs filesystem nor udev is available
then libusbx searches for device nodes also in /dev where they may be
created if the kernel was built with the option CONFIG_USB_DEVICE_CLASS.
This helps on embedded systems such as Android, and all mdev users.

diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c
index 23454cb..a6114ca 100644 (file)
--- a/libusb/os/linux_usbfs.c
+++ b/libusb/os/linux_usbfs.c
@@ -71,6 +71,9 @@
 
 static const char *usbfs_path = NULL;
 
+/* use usbdev*.* device names in /dev instead of the usbfs bus directories */
+static int usbdev_names = 0;
+
 /* Linux 2.6.32 adds support for a bulk continuation URB flag. this basically
  * allows us to mark URBs as being part of a specific logical transfer when
  * we submit them to the kernel. then, on any error except a cancellation, all
@@ -148,8 +151,12 @@ struct linux_transfer_priv {
 
 static void _get_usbfs_path(struct libusb_device *dev, char *path)
 {
-       snprintf(path, PATH_MAX, "%s/%03d/%03d", usbfs_path, dev->bus_number,
-               dev->device_address);
+       if (usbdev_names)
+               snprintf(path, PATH_MAX, "%s/usbdev%d.%d",
+                       usbfs_path, dev->bus_number, dev->device_address);
+       else
+               snprintf(path, PATH_MAX, "%s/%03d/%03d",
+                       usbfs_path, dev->bus_number, dev->device_address);
 }
 
 static struct linux_device_priv *_device_priv(struct libusb_device *dev)
@@ -163,6 +170,23 @@ static struct linux_device_handle_priv *_device_handle_priv(
        return (struct linux_device_handle_priv *) handle->os_priv;
 }
 
+/* check dirent for a /dev/usbdev%d.%d name
+ * optionally return bus/device on success */
+static int _is_usbdev_entry(struct dirent *entry, int *bus_p, int *dev_p)
+{
+       int busnum, devnum;
+
+       if (sscanf(entry->d_name, "usbdev%d.%d", &busnum, &devnum) != 2)
+               return 0;
+
+       usbi_dbg("found: %s", entry->d_name);
+       if (bus_p != NULL)
+               *bus_p = busnum;
+       if (dev_p != NULL)
+               *dev_p = devnum;
+       return 1;
+}
+
 static int check_usb_vfs(const char *dirname)
 {
        DIR *dir;
@@ -199,7 +223,29 @@ static const char *find_usbfs_path(void)
                        ret = path;
        }
 
-       usbi_dbg("found usbfs at %s", ret);
+       /* look for /dev/usbdev*.* if the normal places fail */
+       if (ret == NULL) {
+               struct dirent *entry;
+               DIR *dir;
+
+               path = "/dev";
+               dir = opendir(path);
+               if (dir != NULL) {
+                       while ((entry = readdir(dir)) != NULL) {
+                               if (_is_usbdev_entry(entry, NULL, NULL)) {
+                                       /* found one; that's enough */
+                                       ret = path;
+                                       usbdev_names = 1;
+                                       break;
+                               }
+                       }
+                       closedir(dir);
+               }
+       }
+
+       if (ret != NULL)
+               usbi_dbg("found usbfs at %s", ret);
+
        return ret;
 }
 
@@ -1055,15 +1101,28 @@ static int usbfs_get_device_list(struct libusb_context *ctx,
                if (entry->d_name[0] == '.')
                        continue;
 
-               busnum = atoi(entry->d_name);
-               if (busnum == 0) {
-                       usbi_dbg("unknown dir entry %s", entry->d_name);
-                       continue;
-               }
+               if (usbdev_names) {
+                       int devaddr;
+                       if (!_is_usbdev_entry(entry, &busnum, &devaddr))
+                               continue;
 
-               r = usbfs_scan_busdir(ctx, &discdevs_new, busnum);
-               if (r < 0)
-                       goto out;
+                       r = enumerate_device(ctx, &discdevs_new, busnum,
+                               (uint8_t) devaddr, NULL);
+                       if (r < 0) {
+                               usbi_dbg("failed to enumerate dir entry %s", entry->d_name);
+                               continue;
+                       }
+               } else {
+                       busnum = atoi(entry->d_name);
+                       if (busnum == 0) {
+                               usbi_dbg("unknown dir entry %s", entry->d_name);
+                               continue;
+                       }
+
+                       r = usbfs_scan_busdir(ctx, &discdevs_new, busnum);
+                       if (r < 0)
+                               goto out;
+               }
                discdevs = discdevs_new;
        }
 

diff --git a/libusb/version.h b/libusb/version.h
index 2ebe01f..583e128 100644 (file)
--- a/libusb/version.h
+++ b/libusb/version.h
@@ -9,7 +9,7 @@
 #define LIBUSB_MICRO 10
 #endif
 #ifndef LIBUSB_NANO
-#define LIBUSB_NANO 10483
+#define LIBUSB_NANO 10484
 #endif
 /* LIBUSB_RC is the release candidate suffix. Should normally be empty. */
 #ifndef LIBUSB_RC