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android_system_core/adb/client/usb_linux.cpp
Josh Gao ef3d343254 adb: use the actual wMaxPacketSize for usb endpoints. 
Previously, adb was assuming a fixed maximum packet size of 1024 bytes
(the value for an endpoint connected via USB 3.0). When connected to an
endpoint that has an actual maximum packet size of 512 bytes (i.e.
every single device over USB 2.0), the following could occur:

    device sends amessage with 512 byte payload
    client reads amessage
    client tries to read payload with a length of 1024

In this scenario, the kernel will block, waiting for an additional
packet which won't arrive until something else gets sent across the
wire, which will result in the previous read failing, and the new
packet being dropped.

Bug: http://b/37783561
Test: python test_device.py on linux/darwin, with native/libusb
Change-Id: I556f5344945e22dd1533b076f662a97eea24628e
2017-05-03 12:32:39 -07:00

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/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define TRACE_TAG USB
#include "sysdeps.h"
#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/usb/ch9.h>
#include <linux/usbdevice_fs.h>
#include <linux/version.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <chrono>
#include <condition_variable>
#include <list>
#include <mutex>
#include <string>
#include <thread>
#include <android-base/file.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include "adb.h"
#include "transport.h"
#include "usb.h"
using namespace std::chrono_literals;
using namespace std::literals;
/* usb scan debugging is waaaay too verbose */
#define DBGX(x...)
namespace native {
struct usb_handle : public ::usb_handle {
~usb_handle() {
if (fd != -1) unix_close(fd);
}
std::string path;
int fd = -1;
unsigned char ep_in;
unsigned char ep_out;
size_t max_packet_size;
unsigned zero_mask;
unsigned writeable = 1;
usbdevfs_urb urb_in;
usbdevfs_urb urb_out;
bool urb_in_busy = false;
bool urb_out_busy = false;
bool dead = false;
std::condition_variable cv;
std::mutex mutex;
// for garbage collecting disconnected devices
bool mark;
// ID of thread currently in REAPURB
pthread_t reaper_thread = 0;
};
static auto& g_usb_handles_mutex = *new std::mutex();
static auto& g_usb_handles = *new std::list<usb_handle*>();
static int is_known_device(const char* dev_name) {
std::lock_guard<std::mutex> lock(g_usb_handles_mutex);
for (usb_handle* usb : g_usb_handles) {
if (usb->path == dev_name) {
// set mark flag to indicate this device is still alive
usb->mark = true;
return 1;
}
}
return 0;
}
static void kick_disconnected_devices() {
std::lock_guard<std::mutex> lock(g_usb_handles_mutex);
// kick any devices in the device list that were not found in the device scan
for (usb_handle* usb : g_usb_handles) {
if (!usb->mark) {
usb_kick(usb);
} else {
usb->mark = false;
}
}
}
static inline bool contains_non_digit(const char* name) {
while (*name) {
if (!isdigit(*name++)) return true;
}
return false;
}
static void find_usb_device(const std::string& base,
void (*register_device_callback)(const char*, const char*,
unsigned char, unsigned char, int, int,
unsigned, size_t)) {
std::unique_ptr<DIR, int(*)(DIR*)> bus_dir(opendir(base.c_str()), closedir);
if (!bus_dir) return;
dirent* de;
while ((de = readdir(bus_dir.get())) != 0) {
if (contains_non_digit(de->d_name)) continue;
std::string bus_name = base + "/" + de->d_name;
std::unique_ptr<DIR, int(*)(DIR*)> dev_dir(opendir(bus_name.c_str()), closedir);
if (!dev_dir) continue;
while ((de = readdir(dev_dir.get()))) {
unsigned char devdesc[4096];
unsigned char* bufptr = devdesc;
unsigned char* bufend;
struct usb_device_descriptor* device;
struct usb_config_descriptor* config;
struct usb_interface_descriptor* interface;
struct usb_endpoint_descriptor *ep1, *ep2;
unsigned zero_mask = 0;
size_t max_packet_size = 0;
unsigned vid, pid;
if (contains_non_digit(de->d_name)) continue;
std::string dev_name = bus_name + "/" + de->d_name;
if (is_known_device(dev_name.c_str())) {
continue;
}
int fd = unix_open(dev_name.c_str(), O_RDONLY | O_CLOEXEC);
if (fd == -1) {
continue;
}
size_t desclength = unix_read(fd, devdesc, sizeof(devdesc));
bufend = bufptr + desclength;
// should have device and configuration descriptors, and atleast two endpoints
if (desclength < USB_DT_DEVICE_SIZE + USB_DT_CONFIG_SIZE) {
D("desclength %zu is too small", desclength);
unix_close(fd);
continue;
}
device = (struct usb_device_descriptor*)bufptr;
bufptr += USB_DT_DEVICE_SIZE;
if((device->bLength != USB_DT_DEVICE_SIZE) || (device->bDescriptorType != USB_DT_DEVICE)) {
unix_close(fd);
continue;
}
vid = device->idVendor;
pid = device->idProduct;
DBGX("[ %s is V:%04x P:%04x ]\n", dev_name.c_str(), vid, pid);
// should have config descriptor next
config = (struct usb_config_descriptor *)bufptr;
bufptr += USB_DT_CONFIG_SIZE;
if (config->bLength != USB_DT_CONFIG_SIZE || config->bDescriptorType != USB_DT_CONFIG) {
D("usb_config_descriptor not found");
unix_close(fd);
continue;
}
// loop through all the descriptors and look for the ADB interface
while (bufptr < bufend) {
unsigned char length = bufptr[0];
unsigned char type = bufptr[1];
if (type == USB_DT_INTERFACE) {
interface = (struct usb_interface_descriptor *)bufptr;
bufptr += length;
if (length != USB_DT_INTERFACE_SIZE) {
D("interface descriptor has wrong size");
break;
}
DBGX("bInterfaceClass: %d, bInterfaceSubClass: %d,"
"bInterfaceProtocol: %d, bNumEndpoints: %d\n",
interface->bInterfaceClass, interface->bInterfaceSubClass,
interface->bInterfaceProtocol, interface->bNumEndpoints);
if (interface->bNumEndpoints == 2 &&
is_adb_interface(interface->bInterfaceClass, interface->bInterfaceSubClass,
interface->bInterfaceProtocol)) {
struct stat st;
char pathbuf[128];
char link[256];
char *devpath = nullptr;
DBGX("looking for bulk endpoints\n");
// looks like ADB...
ep1 = (struct usb_endpoint_descriptor *)bufptr;
bufptr += USB_DT_ENDPOINT_SIZE;
// For USB 3.0 SuperSpeed devices, skip potential
// USB 3.0 SuperSpeed Endpoint Companion descriptor
if (bufptr+2 <= devdesc + desclength &&
bufptr[0] == USB_DT_SS_EP_COMP_SIZE &&
bufptr[1] == USB_DT_SS_ENDPOINT_COMP) {
bufptr += USB_DT_SS_EP_COMP_SIZE;
}
ep2 = (struct usb_endpoint_descriptor *)bufptr;
bufptr += USB_DT_ENDPOINT_SIZE;
if (bufptr+2 <= devdesc + desclength &&
bufptr[0] == USB_DT_SS_EP_COMP_SIZE &&
bufptr[1] == USB_DT_SS_ENDPOINT_COMP) {
bufptr += USB_DT_SS_EP_COMP_SIZE;
}
if (bufptr > devdesc + desclength ||
ep1->bLength != USB_DT_ENDPOINT_SIZE ||
ep1->bDescriptorType != USB_DT_ENDPOINT ||
ep2->bLength != USB_DT_ENDPOINT_SIZE ||
ep2->bDescriptorType != USB_DT_ENDPOINT) {
D("endpoints not found");
break;
}
// both endpoints should be bulk
if (ep1->bmAttributes != USB_ENDPOINT_XFER_BULK ||
ep2->bmAttributes != USB_ENDPOINT_XFER_BULK) {
D("bulk endpoints not found");
continue;
}
/* aproto 01 needs 0 termination */
if (interface->bInterfaceProtocol == 0x01) {
max_packet_size = ep1->wMaxPacketSize;
zero_mask = ep1->wMaxPacketSize - 1;
}
// we have a match. now we just need to figure out which is in and which is out.
unsigned char local_ep_in, local_ep_out;
if (ep1->bEndpointAddress & USB_ENDPOINT_DIR_MASK) {
local_ep_in = ep1->bEndpointAddress;
local_ep_out = ep2->bEndpointAddress;
} else {
local_ep_in = ep2->bEndpointAddress;
local_ep_out = ep1->bEndpointAddress;
}
// Determine the device path
if (!fstat(fd, &st) && S_ISCHR(st.st_mode)) {
snprintf(pathbuf, sizeof(pathbuf), "/sys/dev/char/%d:%d",
major(st.st_rdev), minor(st.st_rdev));
ssize_t link_len = readlink(pathbuf, link, sizeof(link) - 1);
if (link_len > 0) {
link[link_len] = '\0';
const char* slash = strrchr(link, '/');
if (slash) {
snprintf(pathbuf, sizeof(pathbuf),
"usb:%s", slash + 1);
devpath = pathbuf;
}
}
}
register_device_callback(dev_name.c_str(), devpath, local_ep_in,
local_ep_out, interface->bInterfaceNumber,
device->iSerialNumber, zero_mask, max_packet_size);
break;
}
} else {
bufptr += length;
}
} // end of while
unix_close(fd);
}
}
}
static int usb_bulk_write(usb_handle* h, const void* data, int len) {
std::unique_lock<std::mutex> lock(h->mutex);
D("++ usb_bulk_write ++");
usbdevfs_urb* urb = &h->urb_out;
memset(urb, 0, sizeof(*urb));
urb->type = USBDEVFS_URB_TYPE_BULK;
urb->endpoint = h->ep_out;
urb->status = -1;
urb->buffer = const_cast<void*>(data);
urb->buffer_length = len;
if (h->dead) {
errno = EINVAL;
return -1;
}
if (TEMP_FAILURE_RETRY(ioctl(h->fd, USBDEVFS_SUBMITURB, urb)) == -1) {
return -1;
}
h->urb_out_busy = true;
while (true) {
auto now = std::chrono::system_clock::now();
if (h->cv.wait_until(lock, now + 5s) == std::cv_status::timeout || h->dead) {
// TODO: call USBDEVFS_DISCARDURB?
errno = ETIMEDOUT;
return -1;
}
if (!h->urb_out_busy) {
if (urb->status != 0) {
errno = -urb->status;
return -1;
}
return urb->actual_length;
}
}
}
static int usb_bulk_read(usb_handle* h, void* data, int len) {
std::unique_lock<std::mutex> lock(h->mutex);
D("++ usb_bulk_read ++");
usbdevfs_urb* urb = &h->urb_in;
memset(urb, 0, sizeof(*urb));
urb->type = USBDEVFS_URB_TYPE_BULK;
urb->endpoint = h->ep_in;
urb->status = -1;
urb->buffer = data;
urb->buffer_length = len;
if (h->dead) {
errno = EINVAL;
return -1;
}
if (TEMP_FAILURE_RETRY(ioctl(h->fd, USBDEVFS_SUBMITURB, urb)) == -1) {
return -1;
}
h->urb_in_busy = true;
while (true) {
D("[ reap urb - wait ]");
h->reaper_thread = pthread_self();
int fd = h->fd;
lock.unlock();
// This ioctl must not have TEMP_FAILURE_RETRY because we send SIGALRM to break out.
usbdevfs_urb* out = nullptr;
int res = ioctl(fd, USBDEVFS_REAPURB, &out);
int saved_errno = errno;
lock.lock();
h->reaper_thread = 0;
if (h->dead) {
errno = EINVAL;
return -1;
}
if (res < 0) {
if (saved_errno == EINTR) {
continue;
}
D("[ reap urb - error ]");
errno = saved_errno;
return -1;
}
D("[ urb @%p status = %d, actual = %d ]", out, out->status, out->actual_length);
if (out == &h->urb_in) {
D("[ reap urb - IN complete ]");
h->urb_in_busy = false;
if (urb->status != 0) {
errno = -urb->status;
return -1;
}
return urb->actual_length;
}
if (out == &h->urb_out) {
D("[ reap urb - OUT compelete ]");
h->urb_out_busy = false;
h->cv.notify_all();
}
}
}
int usb_write(usb_handle *h, const void *_data, int len)
{
D("++ usb_write ++");
unsigned char *data = (unsigned char*) _data;
int n = usb_bulk_write(h, data, len);
if (n != len) {
D("ERROR: n = %d, errno = %d (%s)", n, errno, strerror(errno));
return -1;
}
if (h->zero_mask && !(len & h->zero_mask)) {
// If we need 0-markers and our transfer is an even multiple of the packet size,
// then send a zero marker.
return usb_bulk_write(h, _data, 0);
}
D("-- usb_write --");
return 0;
}
int usb_read(usb_handle *h, void *_data, int len)
{
unsigned char *data = (unsigned char*) _data;
int n;
D("++ usb_read ++");
int orig_len = len;
while (len == orig_len) {
int xfer = len;
D("[ usb read %d fd = %d], path=%s", xfer, h->fd, h->path.c_str());
n = usb_bulk_read(h, data, xfer);
D("[ usb read %d ] = %d, path=%s", xfer, n, h->path.c_str());
if (n <= 0) {
if((errno == ETIMEDOUT) && (h->fd != -1)) {
D("[ timeout ]");
continue;
}
D("ERROR: n = %d, errno = %d (%s)",
n, errno, strerror(errno));
return -1;
}
len -= n;
data += n;
}
D("-- usb_read --");
return orig_len - len;
}
void usb_kick(usb_handle* h) {
std::lock_guard<std::mutex> lock(h->mutex);
D("[ kicking %p (fd = %d) ]", h, h->fd);
if (!h->dead) {
h->dead = true;
if (h->writeable) {
/* HACK ALERT!
** Sometimes we get stuck in ioctl(USBDEVFS_REAPURB).
** This is a workaround for that problem.
*/
if (h->reaper_thread) {
pthread_kill(h->reaper_thread, SIGALRM);
}
/* cancel any pending transactions
** these will quietly fail if the txns are not active,
** but this ensures that a reader blocked on REAPURB
** will get unblocked
*/
ioctl(h->fd, USBDEVFS_DISCARDURB, &h->urb_in);
ioctl(h->fd, USBDEVFS_DISCARDURB, &h->urb_out);
h->urb_in.status = -ENODEV;
h->urb_out.status = -ENODEV;
h->urb_in_busy = false;
h->urb_out_busy = false;
h->cv.notify_all();
} else {
unregister_usb_transport(h);
}
}
}
int usb_close(usb_handle* h) {
std::lock_guard<std::mutex> lock(g_usb_handles_mutex);
g_usb_handles.remove(h);
D("-- usb close %p (fd = %d) --", h, h->fd);
delete h;
return 0;
}
size_t usb_get_max_packet_size(usb_handle* h) {
return h->max_packet_size;
}
static void register_device(const char* dev_name, const char* dev_path, unsigned char ep_in,
unsigned char ep_out, int interface, int serial_index,
unsigned zero_mask, size_t max_packet_size) {
// Since Linux will not reassign the device ID (and dev_name) as long as the
// device is open, we can add to the list here once we open it and remove
// from the list when we're finally closed and everything will work out
// fine.
//
// If we have a usb_handle on the list of handles with a matching name, we
// have no further work to do.
{
std::lock_guard<std::mutex> lock(g_usb_handles_mutex);
for (usb_handle* usb: g_usb_handles) {
if (usb->path == dev_name) {
return;
}
}
}
D("[ usb located new device %s (%d/%d/%d) ]", dev_name, ep_in, ep_out, interface);
std::unique_ptr<usb_handle> usb(new usb_handle);
usb->path = dev_name;
usb->ep_in = ep_in;
usb->ep_out = ep_out;
usb->zero_mask = zero_mask;
usb->max_packet_size = max_packet_size;
// Initialize mark so we don't get garbage collected after the device scan.
usb->mark = true;
usb->fd = unix_open(usb->path.c_str(), O_RDWR | O_CLOEXEC);
if (usb->fd == -1) {
// Opening RW failed, so see if we have RO access.
usb->fd = unix_open(usb->path.c_str(), O_RDONLY | O_CLOEXEC);
if (usb->fd == -1) {
D("[ usb open %s failed: %s]", usb->path.c_str(), strerror(errno));
return;
}
usb->writeable = 0;
}
D("[ usb opened %s%s, fd=%d]",
usb->path.c_str(), (usb->writeable ? "" : " (read-only)"), usb->fd);
if (usb->writeable) {
if (ioctl(usb->fd, USBDEVFS_CLAIMINTERFACE, &interface) != 0) {
D("[ usb ioctl(%d, USBDEVFS_CLAIMINTERFACE) failed: %s]", usb->fd, strerror(errno));
return;
}
}
// Read the device's serial number.
std::string serial_path = android::base::StringPrintf(
"/sys/bus/usb/devices/%s/serial", dev_path + 4);
std::string serial;
if (!android::base::ReadFileToString(serial_path, &serial)) {
D("[ usb read %s failed: %s ]", serial_path.c_str(), strerror(errno));
// We don't actually want to treat an unknown serial as an error because
// devices aren't able to communicate a serial number in early bringup.
// http://b/20883914
serial = "";
}
serial = android::base::Trim(serial);
// Add to the end of the active handles.
usb_handle* done_usb = usb.release();
{
std::lock_guard<std::mutex> lock(g_usb_handles_mutex);
g_usb_handles.push_back(done_usb);
}
register_usb_transport(done_usb, serial.c_str(), dev_path, done_usb->writeable);
}
static void device_poll_thread() {
adb_thread_setname("device poll");
D("Created device thread");
while (true) {
// TODO: Use inotify.
find_usb_device("/dev/bus/usb", register_device);
kick_disconnected_devices();
std::this_thread::sleep_for(1s);
}
}
void usb_init() {
struct sigaction actions;
memset(&actions, 0, sizeof(actions));
sigemptyset(&actions.sa_mask);
actions.sa_flags = 0;
actions.sa_handler = [](int) {};
sigaction(SIGALRM, &actions, nullptr);
std::thread(device_poll_thread).detach();
}
} // namespace native
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