darwin: fix reset device

This commit fixes the backend of reset device to restore the state
of the device if possible. This fixes a bug introduced in
c14ab5fc4d22749aab9e3534d56012718a0b0f67. The previous commit
was necessary due to changes in the system USB stack that
essentially turned the ResetDevice function into a no-op. This
required libusb to move to USBDevuceReEnumerate to effectively
reset the device. The problem is that both the device handle and
libusb devices became invalid. This commit fixes the bug by
waiting for the re-enumeration to complete then 1) checking
whether the descriptors changed, 2) restoring the active
configuration, and 3) restoring claimed interfaces.

Closes #523

Signed-off-by: Nathan Hjelm <hjelmn@me.com>

3 files changed, 154 insertions, 53 deletions

diff --git a/libusb/os/darwin_usb.c b/libusb/os/darwin_usb.c
index 2d6b217..dd391db 100644
--- a/libusb/os/darwin_usb.c
+++ b/libusb/os/darwin_usb.c
@@ -2,6 +2,7 @@
 /*
  * darwin backend for libusb 1.0
  * Copyright © 2008-2019 Nathan Hjelm <hjelmn@users.sourceforge.net>
+ * Copyright © 2019      Google LLC. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -357,11 +358,20 @@ static void darwin_devices_detached (void *ptr, io_iterator_t rem_devices) {
     usbi_mutex_lock(&darwin_cached_devices_lock);
     list_for_each_entry(old_device, &darwin_cached_devices, list, struct darwin_cached_device) {
       if (old_device->session == session) {
-        darwin_deref_cached_device (old_device);
+        if (old_device->in_reenumerate) {
+          /* device is re-enumerating. do not dereference the device at this time. libusb_reset_device()
+           * will deref if needed. */
+          usbi_dbg ("detected device detatched due to re-enumeration");
+        } else {
+          darwin_deref_cached_device (old_device);
+        }
         break;
       }
     }
     usbi_mutex_unlock(&darwin_cached_devices_lock);
+    if (old_device->in_reenumerate) {
+      continue;
+    }
 
     list_for_each_entry(ctx, &active_contexts_list, list, struct libusb_context) {
       usbi_dbg ("notifying context %p of device disconnect", ctx);
@@ -894,12 +904,15 @@ static enum libusb_error darwin_get_cached_device(struct libusb_context *ctx, io
                                                   struct darwin_cached_device **cached_out) {
   struct darwin_cached_device *new_device;
   UInt64 sessionID = 0, parent_sessionID = 0;
+  UInt32 locationID = 0;
   enum libusb_error ret = LIBUSB_SUCCESS;
   usb_device_t **device;
   UInt8 port = 0;
+  bool reuse_device = false;
 
   /* get some info from the io registry */
   (void) get_ioregistry_value_number (service, CFSTR("sessionID"), kCFNumberSInt64Type, &sessionID);
+  (void) get_ioregistry_value_number (service, CFSTR("locationID"), kCFNumberSInt32Type, &locationID);
   if (!get_device_port (service, &port)) {
     usbi_dbg("could not get connected port number");
   }
@@ -915,7 +928,15 @@ static enum libusb_error darwin_get_cached_device(struct libusb_context *ctx, io
     *cached_out = NULL;
 
     list_for_each_entry(new_device, &darwin_cached_devices, list, struct darwin_cached_device) {
-      usbi_dbg("matching sessionID 0x%" PRIx64 " against cached device with sessionID 0x%" PRIx64, sessionID, new_device->session);
+      usbi_dbg("matching sessionID/locationID 0x%" PRIx64 "/0x%x against cached device with sessionID/locationID 0x%" PRIx64 "/0x%x",
+               sessionID, locationID, new_device->session, new_device->location);
+      if (new_device->location == locationID && new_device->in_reenumerate) {
+        usbi_dbg ("found cached device with matching location that is being re-enumerated");
+        new_device->session = sessionID;
+        reuse_device = true;
+        break;
+      }
+
       if (new_device->session == sessionID) {
         usbi_dbg("using cached device for device");
         *cached_out = new_device;
@@ -934,25 +955,28 @@ static enum libusb_error darwin_get_cached_device(struct libusb_context *ctx, io
       break;
     }
 
-    new_device = calloc (1, sizeof (*new_device));
-    if (!new_device) {
-      ret = LIBUSB_ERROR_NO_MEM;
-      break;
-    }
+    if (!reuse_device) {
+      new_device = calloc (1, sizeof (*new_device));
+      if (!new_device) {
+        ret = LIBUSB_ERROR_NO_MEM;
+        break;
+      }
 
-    /* add this device to the cached device list */
-    list_add(&new_device->list, &darwin_cached_devices);
+      /* add this device to the cached device list */
+      list_add(&new_device->list, &darwin_cached_devices);
 
-    (*device)->GetDeviceAddress (device, (USBDeviceAddress *)&new_device->address);
+      (*device)->GetDeviceAddress (device, (USBDeviceAddress *)&new_device->address);
 
-    /* keep a reference to this device */
-    darwin_ref_cached_device(new_device);
+      /* keep a reference to this device */
+      darwin_ref_cached_device(new_device);
+
+      new_device->session = sessionID;
+      (*device)->GetLocationID (device, &new_device->location);
+      new_device->port = port;
+      new_device->parent_session = parent_sessionID;
+    }
 
     new_device->device = device;
-    new_device->session = sessionID;
-    (*device)->GetLocationID (device, &new_device->location);
-    new_device->port = port;
-    new_device->parent_session = parent_sessionID;
 
     /* cache the device descriptor */
     ret = darwin_cache_device_descriptor(ctx, new_device);
@@ -985,7 +1009,6 @@ static enum libusb_error process_new_device (struct libusb_context *ctx, io_serv
 
   do {
     ret = darwin_get_cached_device (ctx, service, &cached_device);
-
     if (ret < 0 || !cached_device->can_enumerate) {
       return ret;
     }
@@ -1041,9 +1064,13 @@ static enum libusb_error process_new_device (struct libusb_context *ctx, io_serv
 
     usbi_dbg ("found device with address %d port = %d parent = %p at %p", dev->device_address,
               dev->port_number, (void *) dev->parent_dev, priv->dev->sys_path);
+
   } while (0);
 
-  if (0 == ret) {
+  if (cached_device->in_reenumerate) {
+    usbi_dbg ("cached device in reset state. reset complete...");
+    cached_device->in_reenumerate = false;
+  } else if (0 == ret) {
     usbi_connect_device (dev);
   } else {
     libusb_unref_device (dev);
@@ -1088,9 +1115,9 @@ static int darwin_open (struct libusb_device_handle *dev_handle) {
       }
 
       /* it is possible to perform some actions on a device that is not open so do not return an error */
-      priv->is_open = 0;
+      priv->is_open = false;
     } else {
-      priv->is_open = 1;
+      priv->is_open = true;
     }
 
     /* create async event source */
@@ -1102,7 +1129,7 @@ static int darwin_open (struct libusb_device_handle *dev_handle) {
         (*(dpriv->device))->USBDeviceClose (dpriv->device);
       }
 
-      priv->is_open = 0;
+      priv->is_open = false;
 
       return darwin_to_libusb (kresult);
     }
@@ -1482,57 +1509,127 @@ static int darwin_clear_halt(struct libusb_device_handle *dev_handle, unsigned c
   return darwin_to_libusb (kresult);
 }
 
+static int darwin_restore_state (struct libusb_device_handle *dev_handle, int8_t active_config,
+                                 unsigned long claimed_interfaces) {
+  struct darwin_cached_device *dpriv = DARWIN_CACHED_DEVICE(dev_handle->dev);
+  struct darwin_device_handle_priv *priv = (struct darwin_device_handle_priv *)dev_handle->os_priv;
+  int open_count = dpriv->open_count;
+  int ret;
+
+  /* clear claimed interfaces temporarily */
+  dev_handle->claimed_interfaces = 0;
+
+  /* close and re-open the device */
+  priv->is_open = false;
+  dpriv->open_count = 1;
+
+  /* clean up open interfaces */
+  (void) darwin_close (dev_handle);
+
+  /* re-open the device */
+  ret = darwin_open (dev_handle);
+  dpriv->open_count = open_count;
+  if (LIBUSB_SUCCESS != ret) {
+    /* could not restore configuration */
+    return LIBUSB_ERROR_NOT_FOUND;
+  }
+
+  if (dpriv->active_config != active_config) {
+    usbi_dbg ("darwin/restore_state: restoring configuration %d...", active_config);
+
+    ret = darwin_set_configuration (dev_handle, active_config);
+    if (LIBUSB_SUCCESS != ret) {
+      usbi_dbg ("darwin/restore_state: could not restore configuration");
+      return LIBUSB_ERROR_NOT_FOUND;
+    }
+  }
+
+  usbi_dbg ("darwin/restore_state: reclaiming interfaces");
+
+  if (claimed_interfaces) {
+    for (int iface = 0 ; iface < USB_MAXINTERFACES ; ++iface) {
+      if (!(claimed_interfaces & (1U << iface))) {
+        continue;
+      }
+
+      usbi_dbg ("darwin/restore_state: re-claiming interface %d", iface);
+
+      ret = darwin_claim_interface (dev_handle, iface);
+      if (LIBUSB_SUCCESS != ret) {
+        usbi_dbg ("darwin/restore_state: could not claim interface %d", iface);
+        return LIBUSB_ERROR_NOT_FOUND;
+      }
+
+      dev_handle->claimed_interfaces |= 1U << iface;
+    }
+  }
+
+  usbi_dbg ("darwin/restore_state: device state restored");
+
+  return LIBUSB_SUCCESS;
+}
+
 static int darwin_reset_device(struct libusb_device_handle *dev_handle) {
   struct darwin_cached_device *dpriv = DARWIN_CACHED_DEVICE(dev_handle->dev);
+  unsigned long claimed_interfaces = dev_handle->claimed_interfaces;
+  int8_t active_config = dpriv->active_config;
   IOUSBDeviceDescriptor descriptor;
   IOUSBConfigurationDescriptorPtr cached_configuration;
-  IOUSBConfigurationDescriptor configuration;
-  bool reenumerate = false;
+  IOUSBConfigurationDescriptor *cached_configurations;
   IOReturn kresult;
   UInt8 i;
 
+  if (dpriv->in_reenumerate) {
+    /* ack, two (or more) threads are trying to reset the device! abort! */
+    return LIBUSB_ERROR_NOT_FOUND;
+  }
+
+  dpriv->in_reenumerate = true;
+
+  /* store copies of descriptors so they can be compared after the reset */
+  memcpy (&descriptor, &dpriv->dev_descriptor, sizeof (descriptor));
+  cached_configurations = alloca (sizeof (*cached_configurations) * descriptor.bNumConfigurations);
+
+  for (i = 0 ; i < descriptor.bNumConfigurations ; ++i) {
+    (*(dpriv->device))->GetConfigurationDescriptorPtr (dpriv->device, i, &cached_configuration);
+    memcpy (cached_configurations + i, cached_configuration, sizeof (cached_configurations[i]));
+  }
+
   /* from macOS 10.11 ResetDevice no longer does anything so just use USBDeviceReEnumerate */
   kresult = (*(dpriv->device))->USBDeviceReEnumerate (dpriv->device, 0);
   if (kresult != kIOReturnSuccess) {
     usbi_err (HANDLE_CTX (dev_handle), "USBDeviceReEnumerate: %s", darwin_error_str (kresult));
+    dpriv->in_reenumerate = false;
     return darwin_to_libusb (kresult);
   }
 
-  do {
-    usbi_dbg ("darwin/reset_device: checking if device descriptor changed");
-
-    /* ignore return code. if we can't get a descriptor it might be worthwhile re-enumerating anway */
-    (void) darwin_request_descriptor (dpriv->device, kUSBDeviceDesc, 0, &descriptor, sizeof (descriptor));
+  usbi_dbg ("darwin/reset_device: waiting for re-enumeration to complete...");
 
-    /* check if the device descriptor has changed */
-    if (0 != memcmp (&dpriv->dev_descriptor, &descriptor, sizeof (descriptor))) {
-      reenumerate = true;
-      break;
-    }
+  while (dpriv->in_reenumerate) {
+    struct timespec delay = {.tv_sec = 0, .tv_nsec = 1000};
+    nanosleep (&delay, NULL);
+  }
 
-    /* check if any configuration descriptor has changed */
-    for (i = 0 ; i < descriptor.bNumConfigurations ; ++i) {
-      usbi_dbg ("darwin/reset_device: checking if configuration descriptor %d changed", i);
+  /* compare descriptors */
+  usbi_dbg ("darwin/reset_device: checking whether descriptors changed");
 
-      (void) darwin_request_descriptor (dpriv->device, kUSBConfDesc, i, &configuration, sizeof (configuration));
-      (*(dpriv->device))->GetConfigurationDescriptorPtr (dpriv->device, i, &cached_configuration);
+  if (memcmp (&descriptor, &dpriv->dev_descriptor, sizeof (descriptor))) {
+    /* device descriptor changed. need to return not found. */
+    usbi_dbg ("darwin/reset_device: device descriptor changed");
+    return LIBUSB_ERROR_NOT_FOUND;
+  }
 
-      if (!cached_configuration || 0 != memcmp (cached_configuration, &configuration, sizeof (configuration))) {
-        reenumerate = true;
-        break;
-      }
+  for (i = 0 ; i < descriptor.bNumConfigurations ; ++i) {
+    (void) (*(dpriv->device))->GetConfigurationDescriptorPtr (dpriv->device, i, &cached_configuration);
+    if (memcmp (cached_configuration, cached_configurations + i, sizeof (cached_configurations[i]))) {
+      usbi_dbg ("darwin/reset_device: configuration descriptor %d changed", i);
+      return LIBUSB_ERROR_NOT_FOUND;
     }
-  } while (0);
-
-  if (reenumerate) {
-    usbi_dbg ("darwin/reset_device: device requires reenumeration");
-    (void) (*(dpriv->device))->USBDeviceReEnumerate (dpriv->device, 0);
-    return LIBUSB_ERROR_NOT_FOUND;
   }
 
-  usbi_dbg ("darwin/reset_device: device reset complete");
+  usbi_dbg ("darwin/reset_device: device reset complete. restoring state...");
 
-  return LIBUSB_SUCCESS;
+  return darwin_restore_state (dev_handle, active_config, claimed_interfaces);
 }
 
 static int darwin_kernel_driver_active(struct libusb_device_handle *dev_handle, int interface) {
diff --git a/libusb/os/darwin_usb.h b/libusb/os/darwin_usb.h
index 8a728bc..3d76baf 100644
--- a/libusb/os/darwin_usb.h
+++ b/libusb/os/darwin_usb.h
@@ -1,6 +1,7 @@
 /*
  * darwin backend for libusb 1.0
- * Copyright © 2008-2015 Nathan Hjelm <hjelmn@users.sourceforge.net>
+ * Copyright © 2008-2019 Nathan Hjelm <hjelmn@users.sourceforge.net>
+ * Copyright © 2019      Google LLC. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -20,6 +21,8 @@
 #if !defined(LIBUSB_DARWIN_H)
 #define LIBUSB_DARWIN_H
 
+#include <stdbool.h>
+
 #include "libusbi.h"
 
 #include <IOKit/IOTypes.h>
@@ -162,6 +165,7 @@ struct darwin_cached_device {
   UInt8                 first_config, active_config, port;  
   int                   can_enumerate;
   int                   refcount;
+  bool                  in_reenumerate;
 };
 
 struct darwin_device_priv {
@@ -169,7 +173,7 @@ struct darwin_device_priv {
 };
 
 struct darwin_device_handle_priv {
-  int                  is_open;
+  bool                 is_open;
   CFRunLoopSourceRef   cfSource;
 
   struct darwin_interface {
diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index c308dff..dc15091 100644
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 11347
+#define LIBUSB_NANO 11348