I want my Android application to create a fake virtual device, to achieve this the device needs to be rooted and uinput module is needed.
I am using the following code to create the device, calling
static{ System.loadLibrary("myModule"); }
CreateVirtualDevice("Devname",0x123,0x123);
inside my java code.
Here the native code:
#include <string.h>
#include <jni.h>
#include <fcntl.h>
#include <linux/input.h>
#include <linux/uinput.h>
static int fd;
static struct uinput_user_dev dev;
short int analog_axis_list[] = { ABS_X,ABS_Y,ABS_RX,ABS_RY, -1};
jint Java_com_example_app_MyClass_CreateVirtualDevice(
JNIEnv* env, jobject thiz, jstring param, jint param2, jint param3) {
int i;
memset(&dev, 0, sizeof(dev));
fd = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
if (fd < 0)
return -1;
if(ioctl(fd, UI_SET_EVBIT, EV_ABS)<0) return -4;
for(i=0;analog_axis_list[i]>=0;i++){
if(ioctl(fd,UI_SET_ABSBIT,analog_axis_list[i])<0) return -5;
dev.absmax[analog_axis_list[i]]=32767;
dev.absmin[analog_axis_list[i]]=-32768;
}
const char *cparam = (*env)->GetStringUTFChars(env, param, 0);
snprintf(dev.name, UINPUT_MAX_NAME_SIZE, cparam);
(*env)->ReleaseStringUTFChars(env, param, cparam);
dev.id.bustype = BUS_VIRTUAL;
dev.id.vendor = param2;
dev.id.product = param3;
dev.id.version = 1;
if (write(fd, &dev, sizeof(dev)) < 0)
return -7;
if (ioctl(fd, UI_DEV_CREATE) < 0)
return -8;
return 0;
}
The device is successfully created, and the return value is 0.
Inside input.h the ABS values are so defined:
#define ABS_X 0x00
#define ABS_Y 0x01
#define ABS_RX 0x03
#define ABS_RY 0x04
But when checking the axis on android, I get proper values for AXIS_X and AXIS_Y, but ABS_RX and ABS_RY have wrong values. I used this code to check the axis values:
InputDevice device = InputDevice.getDevice(ids[position]);
List<InputDevice.MotionRange> ranges = device.getMotionRanges();
StringBuilder sb = new StringBuilder("");
if(ranges.size()==0){
sb.append("NO_MOTION_RANGES");
}
else{
int i = 0;
for(InputDevice.MotionRange range:ranges) {
if(i>0) {
sb.append(",");
}
sb.append(MotionEvent.axisToString(range.getAxis()));
sb.append("(").append(range.getAxis()).append(")");
i++;
}
}
return sb.toString();
And the result is:
AXIS_X(0),AXIS_Y(1),AXIS_Z(11),AXIS_RZ(14)
I am using the latest NDK release (r10d) without any particular settings enabled. What can cause these errors?
I want to point out that it's my code to have something wrong, because with an actual controller the axis numbers are correct.
Edit 1:
I tried to return analog_axis_list[2], which is ABS_RX, at the end of my function instead of 0 and it returns 3, so I think I'm passing a wrong type to the ioctl call.
Which type should I choose?
Android uses AXIS_Z and AXIS_RZ for the right stick; this is consistent with USB HID.
Related
I am trying to set the baud-rate of "/dev/ttyS4" and return the Text(EditText) using C code with the help of JNI in android studio
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <termios.h>
#define DEBUG 1
#if DEBUG
#include <android/log.h>
# define D(x...) __android_log_print(ANDROID_LOG_INFO,"hello-jni",x)
#else
# define D(...) do {} while (0)
#endif
char* str;
char buffer[512];
extern "C" JNIEXPORT jstring JNICALL
Java_com_android_uart_MainActivity_stringFromJNI(
JNIEnv* env,
jobject /* this */, jstring text)
{
{
asprintf(&str, "Hi\n");
strlcpy(buffer, str, sizeof buffer);
free(str);
int ttyFD = 0;
struct termios tty;
const char *stringInC = env->GetStringUTFChars(text, NULL);
auto SampleCmd = stringInC;
int i_WriteBytes = 0;
memset (&tty, 0, sizeof tty);
ttyFD = open("/dev/ttyS4", O_RDWR| O_NONBLOCK | O_NDELAY );
if(ttyFD < 0)
{
asprintf(&str, "Error in opening /dev/ttyS4\n");
strlcat(buffer, str, sizeof buffer);
free(str);
}
else
{
asprintf(&str, "ttyS4 port opened successfully\n");
strlcat(buffer, str, sizeof buffer);
free(str);
}
if (tcgetattr ( ttyFD, &tty ) != 0 )
{
asprintf(&str, "Error from tcgetattr\n");
strlcat(buffer, str, sizeof buffer);
free(str);
}
cfsetspeed(&tty, B0);
tty.c_cflag &= ~PARENB; /* parity */
tty.c_cflag &= ~CSTOPB; /* stop bits */
//tty.c_cflag &= ~CSIZE; /* */
tty.c_cflag |= CS8; /* data bits */
tty.c_cflag &= ~CRTSCTS; /* no hardware flow control */
tty.c_iflag &= ~(IXON | IXOFF | IXANY); /* no s/w flow ctrl */
tty.c_lflag = 0; /* non canonical */
tty.c_oflag = 0; /* no remapping, no delays */
tty.c_cc[VMIN] = 0; /* read doesn't block */
tty.c_cc[VTIME] = 0; /* read timeout */
tty.c_cflag |=
CREAD | CLOCAL; /* turn on READ & ignore ctrl lines */
tty.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG); /* */
//tty.c_oflag &= ~OPOST; /* */
tcflush(ttyFD, TCIFLUSH);
if (tcsetattr(ttyFD, TCSANOW, &tty) != 0) {
asprintf(&str, "Error from tcsetattr\n");
strlcat(buffer, str, sizeof buffer);
free(str);
}
i_WriteBytes = write(ttyFD, SampleCmd, sizeof(SampleCmd) - 1);
asprintf(&str, "written bytes = %d\n", i_WriteBytes);
strlcat(buffer, str, sizeof buffer);
free(str);
if (i_WriteBytes < 0) {
asprintf(&str, "failed to write value on port\n");
strlcat(buffer, str, sizeof buffer);
free(str);
}
sleep(1);
char read_buf[1024];
memset(&read_buf, '\0', sizeof(read_buf));
int num_bytes = read(ttyFD, &read_buf, sizeof(read_buf));
if (num_bytes < 0) {
asprintf(&str, "Error reading: %s", strerror(errno));
strlcat(buffer, str, sizeof buffer);
free(str);
}
asprintf(&str, "Read bytes = %i \n Received message: %s", num_bytes, read_buf);
strlcat(buffer, str, sizeof buffer);
free(str);
close(ttyFD);
return env->NewStringUTF(buffer);
}
My problem is that WriteBytes and Read bytes only take 7 bytes of the edittext"Text" and it only display 7 characters of it.
What i want is to display the entire "Text" from the EditText.
This is the result iam getting:
**Input:**
EditText(baud Rate)=0
EditText(message) =this is a test app
**Output:**
TextView(Details)
hi
ttyS4 port opened successfully
written bytes = 7
Read bytes =7
Received message:this is
The line
i_WriteBytes = write(ttyFD, SampleCmd, sizeof(SampleCmd) - 1);
is wrong.
Variable SampleCmd, defined as
const char *stringInC = env->GetStringUTFChars(text, NULL);
auto SampleCmd = stringInC;
is of type int in C or type const char * in C++. (Note that auto is an old keyword in C which defines a storage class is the default for variables inside functions and forbidden at file scope. As you don't specify a type, it defaults to int.)
The value sizeof(SampleCmd) is not related to the length of the string pointed to by stringInC. It is the size of a variable of type int (in C, or type char* in C++). Apparently this size is 8 on your platform, so you will always write 7 bytes.
You could use
i_WriteBytes = write(ttyFD, SampleCmd, strlen(SampleCmd));
or use fdopen on ttyFD and use output functions from stdio.h.
I use superpowered, I need send midi note to a controller midi.
The problem is that I saw a function send(int deviceID, unsigned char *data, int bytes);
Where in their source code say:
deviceID: Device identifier.
data: Raw MIDI data.
bytes: Number of
bytes.
I don't know the values that I need put exactly on data and bytes to work.
The raw midi could be 0x80 - 0x48 - 0x00(start of C4 note, pitch= 72, See values)
And the bytes 1001nnnn0kkkkkkk0kkkkkkk(note on event See values) for example?
Something like that:
SuperpoweredUSBMIDI::send(deviceID, reinterpret_cast(0x80 - 0x48 - 0x00), 1001nnnn0kkkkkkk0kkkkkkk);
The problem that always crash, and I can't debug or get the error for the reason that I use the mobile with otg to replicate the error.
When I find a solution, I will put it as soon as I can.
I'm newbie with markdown, sorry for any mistakes and my English grammar.
Edit: I'm using the example project that they have on GitHub for testing purposes, specifically the simpleusb project. (source)
I make a small modifications and work, but with this specifically I try with many ways and nothing. I think this simple macrochange at least could work if I insert well the values
class simpleusb.cpp:
#include <jni.h>
#include <math.h>
#include <SuperpoweredCPU.h>
#include <AndroidIO/SuperpoweredUSBAudio.h>
#include <malloc.h>
#include <pthread.h>
// Called when the application is initialized. You can initialize SuperpoweredUSBSystem
// at any time btw. Although this function is marked __unused, it's due Android Studio's
// annoying warning only. It's definitely used.
__unused jint JNI_OnLoad (
JavaVM * __unused vm,
void * __unused reserved
) {
SuperpoweredUSBSystem::initialize(NULL, NULL, NULL, NULL, NULL);
return JNI_VERSION_1_6;
}
// Called when the application is closed. You can destroy SuperpoweredUSBSystem at any time btw.
// Although this function is marked __unused, it's due Android Studio's annoying warning only.
// It's definitely used.
__unused void JNI_OnUnload (
JavaVM * __unused vm,
void * __unused reserved
) {
SuperpoweredUSBSystem::destroy();
}
// A helper structure for sine wave output.
typedef struct sineWaveOutput {
float mul;
unsigned int step;
} sineWaveOutput;
// This is called periodically for audio I/O. Audio is always 32-bit floating point,
// regardless of the bit depth preference. (SuperpoweredUSBAudioProcessingCallback)
static bool audioProcessing (
void *clientdata,
int __unused deviceID,
float *audioIO,
int numberOfSamples,
int samplerate,
int __unused numInputChannels,
int numOutputChannels
) {
// If audioIO is NULL, then it's the very last call, IO is closing.
if (!audioIO) {
// Free memory for sine wave struct.
free(clientdata);
return true;
}
sineWaveOutput *swo = (sineWaveOutput *)clientdata;
if (swo->mul == 0.0f) swo->mul = (2.0f * float(M_PI) * 300.0f) / float(samplerate);
// Output sine wave on all output channels.
for (int n = 0; n < numberOfSamples; n++) {
float v = sinf(swo->step++ * swo->mul) * 0.5f;
for (int c = 0; c < numOutputChannels; c++) *audioIO++ = v;
}
return true; // Return false for silence, true if we put audio output into audioIO.
}
static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
static int latestMidiCommand = -1;
static int latestMidiChannel = 0;
static int latestMidiNumber = 0;
static int latestMidiValue = 0;
// This is called when some MIDI data is coming in.
// We are doing some primitive MIDI data processing here.
static void onMidiReceived (
void * __unused clientdata,
int __unused deviceID,
unsigned char *data,
int bytes
) {
while (bytes > 0) {
if (*data > 127) {
int command = *data >> 4;
switch (command) {
case 8: // note off
case 9: // note on
case 11: // control change
pthread_mutex_lock(&mutex);
// store incoming MIDI data
latestMidiCommand = command;
latestMidiChannel = *data++ & 15;
latestMidiNumber = *data++;
latestMidiValue = *data++;
pthread_mutex_unlock(&mutex);
bytes -= 3;
break;
default:
data++;
bytes--;
}
} else {
data++;
bytes--;
}
}
}
// Beautifying the ugly Java-C++ bridge (JNI) with these macros.
#define PID com_superpowered_simpleusb_SuperpoweredUSBAudio // Java package name and class name. Don't forget to update when you copy this code.
#define MAKE_JNI_FUNCTION(r, n, p) extern "C" JNIEXPORT r JNICALL Java_ ## p ## _ ## n
#define JNI(r, n, p) MAKE_JNI_FUNCTION(r, n, p)
// This is called by the SuperpoweredUSBAudio Java object when a USB device is connected.
JNI(jint, onConnect, PID) (
JNIEnv *env,
jobject __unused obj,
jint deviceID,
jint fd,
jbyteArray rawDescriptor
) {
jbyte *rd = env->GetByteArrayElements(rawDescriptor, NULL);
int dataBytes = env->GetArrayLength(rawDescriptor);
int r = SuperpoweredUSBSystem::onConnect(deviceID, fd, (unsigned char *)rd, dataBytes);
env->ReleaseByteArrayElements(rawDescriptor, rd, JNI_ABORT);
// r is 0 if SuperpoweredUSBSystem can't do anything with the connected device.
// r & 2 is true if the device has MIDI. Start receiving events.
if (r & 2) {
SuperpoweredUSBMIDI::startIO(deviceID, NULL, onMidiReceived);
//TODO HERE IT'S THE PROBLEM: error: integer literal is too large to be represented in any integer type
SuperpoweredUSBMIDI::send(deviceID, reinterpret_cast<unsigned char *>(0x80 - 0x48 - 0x00), 100100010011100000000011);
//FINISH PROBLEM
}
// r & 1 is true if the device has audio. Start output.
if (r & 1) {
// allocate struct for sine wave oscillator
sineWaveOutput *swo = (sineWaveOutput *)malloc(sizeof(sineWaveOutput));
if (swo) {
swo->mul = 0.0f;
swo->step = 0;
SuperpoweredCPU::setSustainedPerformanceMode(true);
// Our preferred settings: 44100 Hz, 16 bits, 0 input channels, 256 output channels,
// low latency. Superpowered will set up the audio device as close as it can to these.
SuperpoweredUSBAudio::easyIO (
deviceID, // deviceID
44100, // sampling rate
16, // bits per sample
0, // numInputChannels
256, // numOutputChannels
SuperpoweredUSBLatency_Low, // latency
swo, // clientData
audioProcessing // SuperpoweredUSBAudioProcessingCallback
);
}
}
return r;
}
// This is called by the SuperpoweredUSBAudio Java object when a USB device is disconnected.
JNI(void, onDisconnect, PID) (
JNIEnv * __unused env,
jobject __unused obj,
jint deviceID
) {
SuperpoweredUSBSystem::onDisconnect(deviceID);
SuperpoweredCPU::setSustainedPerformanceMode(false);
}
#undef PID
#define PID com_superpowered_simpleusb_MainActivity
// This is called by the MainActivity Java object periodically.
JNI(jintArray, getLatestMidiMessage, PID) (
JNIEnv *env,
jobject __unused obj
) {
jintArray ints = env->NewIntArray(4);
jint *i = env->GetIntArrayElements(ints, 0);
pthread_mutex_lock(&mutex);
i[0] = latestMidiCommand;
i[1] = latestMidiChannel;
i[2] = latestMidiNumber;
i[3] = latestMidiValue;
pthread_mutex_unlock(&mutex);
env->ReleaseIntArrayElements(ints, i, 0);
return ints;
}
The other important class but I don't change on this problem, MainActivity:
#RequiresApi(api = Build.VERSION_CODES.M)
public class MainActivity extends AppCompatActivity implements SuperpoweredUSBAudioHandler {
private Handler handler;
private TextView textView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = findViewById(R.id.text);
SuperpoweredUSBAudio usbAudio = new SuperpoweredUSBAudio(getApplicationContext(), this);
usbAudio.check();
// Update UI every 40 ms.
Runnable runnable = new Runnable() {
#Override
public void run() {
int[] midi = getLatestMidiMessage();
switch (midi[0]) {
case 8: textView.setText(String.format(Locale.ENGLISH, "Note Off, CH %d, %d, %d",
midi[1] + 1, midi[2], midi[3]));
break;
case 9: textView.setText(String.format(Locale.ENGLISH, "Note On, CH %d, %d, %d",
midi[1] + 1, midi[2], midi[3]));
break;
case 11: textView.setText(String.format(Locale.ENGLISH, "Control Change, CH %d, %d, %d",
midi[1] + 1, midi[2], midi[3]));
break;
}
handler.postDelayed(this, 40);
}
};
handler = new Handler();
handler.postDelayed(runnable, 40);
/*Not look, only for testing purposes and for remember what use.
byte[] buffer = new byte[32];
int numBytes = 0;
int channel = 6; // MIDI channels 1-16 are encoded as 0-15.
buffer[numBytes++] = (byte)(0x90 + (channel - 1)); // note on
buffer[numBytes++] = (byte)60; // pitch is middle C
buffer[numBytes++] = (byte)127; // max velocity
int offset = 0;*/
}
public void onUSBAudioDeviceAttached(int deviceIdentifier) {
}
public void onUSBMIDIDeviceAttached(int deviceIdentifier) {
}
public void onUSBDeviceDetached(int deviceIdentifier) {
}
// Function implemented in the native library.
private native int[] getLatestMidiMessage();
static {
System.loadLibrary("SuperpoweredExample");
}
}
Error that I can't build app finally:
Build command failed.
Error while executing process D:\Users\ramoc\AppData\Local\Android\sdk\cmake\3.6.4111459\bin\cmake.exe with arguments {--build F:\PROYECTOFIN\SuperpoweredUSBExample\simpleusb\.externalNativeBuild\cmake\debug\arm64-v8a --target SuperpoweredExample}
[1/2] Building CXX object CMakeFiles/SuperpoweredExample.dir/simpleusb.cpp.o
FAILED: D:\Users\ramoc\AppData\Local\Android\sdk\ndk-bundle\toolchains\llvm\prebuilt\windows-x86_64\bin\clang++.exe --target=aarch64-none-linux-android --gcc-toolchain=D:/Users/ramoc/AppData/Local/Android/sdk/ndk-bundle/toolchains/aarch64-linux-android-4.9/prebuilt/windows-x86_64 --sysroot=D:/Users/ramoc/AppData/Local/Android/sdk/ndk-bundle/sysroot -DSuperpoweredExample_EXPORTS -IF:/PROYECTOFIN/SuperpoweredUSBExample/simpleusb/src/main/jni/src/main/jni -IF:/PROYECTOFIN/SuperpoweredUSBExample/simpleusb/../../../Superpowered -isystem D:/Users/ramoc/AppData/Local/Android/sdk/ndk-bundle/sources/cxx-stl/gnu-libstdc++/4.9/include -isystem D:/Users/ramoc/AppData/Local/Android/sdk/ndk-bundle/sources/cxx-stl/gnu-libstdc++/4.9/libs/arm64-v8a/include -isystem D:/Users/ramoc/AppData/Local/Android/sdk/ndk-bundle/sources/cxx-stl/gnu-libstdc++/4.9/include/backward -isystem D:/Users/ramoc/AppData/Local/Android/sdk/ndk-bundle/sysroot/usr/include/aarch64-linux-android -D__ANDROID_API__=21 -g -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -Wa,--noexecstack -Wformat -Werror=format-security -fsigned-char -IF:\PROYECTOFIN\SuperpoweredUSBExample\simpleusb\..\..\..\Superpowered -O0 -fno-limit-debug-info -fPIC -MD -MT CMakeFiles/SuperpoweredExample.dir/simpleusb.cpp.o -MF CMakeFiles\SuperpoweredExample.dir\simpleusb.cpp.o.d -o CMakeFiles/SuperpoweredExample.dir/simpleusb.cpp.o -c F:\PROYECTOFIN\SuperpoweredUSBExample\simpleusb\src\main\jni\simpleusb.cpp
F:\PROYECTOFIN\SuperpoweredUSBExample\simpleusb\src\main\jni\simpleusb.cpp:129:100: error: integer literal is too large to be represented in any integer type
SuperpoweredUSBMIDI::send(deviceID, reinterpret_cast<unsigned char *>(0x80 - 0x48 - 0x00), 100100010011100000000011);
^
F:\PROYECTOFIN\SuperpoweredUSBExample\simpleusb\src\main\jni\simpleusb.cpp:129:100: warning: implicit conversion from 'unsigned long long' to 'int' changes value from 7976667151972931595 to 887068683 [-Wconstant-conversion]
SuperpoweredUSBMIDI::send(deviceID, reinterpret_cast<unsigned char *>(0x80 - 0x48 - 0x00), 100100010011100000000011);
~~~~~~~~~~~~~~~~~~~ ^~~~~~~~~~~~~~~~~~~~~~~~
1 warning and 1 error generated.
ninja: build stopped: subcommand failed.
Maybe it's for the documentation, very newbie with jni or too complex to me for now to understand 100%.
Ok, so here's what send is saying:
send(int deviceID, unsigned char *data, int bytes);
Send to deviceId a pointer to a buffer called data that has a certain number of bytes.
So when you say:
SuperpoweredUSBMIDI::send(deviceID, reinterpret_cast(0x80 - 0x48 - 0x00), 100100010011100000000011);
What you are essentially saying is "subtract these 3 numbers: 0x80 - 0x48 - 0x00", then re-interpret that number as a pointer to a buffer somewhere in memory. That buffer in memory contains 100100010011100000000011 bytes of data that I want you to read.
To fix this, we would send the data like this:
unsigned char* send_buffer[32] = {0}; // zero out buffer to use as scratch
send_buffer[0] = 0x90;
send_buffer[1] = 0x48;
send_buffer[2] = 0x00;
SuperpoweredUSBMIDI::send(deviceID, send_buffer, 3);
i thought midi had a check sum value (byte) appended to the sequence - is that done in your code or in the library code?
the message should be an array of unsigned char and pass the address of the array (name)
well that's what id have done in C when I was programming midi.
I'm trying to share data between kernel and user space. The ultimate goal is to port it to Android, so I'm using unix domain sockets. (I don't know if this is the best option).
I have a kernel module acting as socket client and a c program acting as socket server. And vice-versa, a kernel module acting as socket server and a c program acting as socket client.
Programs are very simple. Servers just send a string to clients and they print it.
I run server_user.c and then I try to insert client_module.ko using insmod. I get the following error:
Kernel panic - not syncing: stack - protector: Kernel stack is corrupted in: ffffffffa0005157
drm-kms-helper: panic occurred, switching back to text console
What's wrong?
Module Server
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/socket.h>
#include <linux/net.h>
#include <linux/un.h>
#include <net/sock.h>
#define SOCK_PATH "/tmp/usocket"
#define LISTEN 10
struct socket *sock = NULL;
struct socket *newsock = NULL;
static int __init server_module_init( void ) {
int retval;
char* string = "hello_world";
struct sockaddr_un addr;
struct msghdr msg;
struct iovec iov;
mm_segment_t oldfs;
// create
retval = sock_create(AF_UNIX, SOCK_STREAM, 0, &sock);
memset(&addr, 0, sizeof(addr));
addr.sun_family = AF_UNIX;
strcpy(addr.sun_path, SOCK_PATH);
// bind
retval = sock->ops->bind(sock,(struct sockaddr *)&addr, sizeof(addr));
// listen
retval = sock->ops->listen(sock, LISTEN);
//accept
retval = sock->ops->accept(sock, newsock, 0);
//sendmsg
memset(&msg, 0, sizeof(msg));
memset(&iov, 0, sizeof(iov));
msg.msg_name = 0;
msg.msg_namelen = 0;
msg.msg_iov = &iov;
msg.msg_iov->iov_base = string;
msg.msg_iov->iov_len = strlen(string)+1;
msg.msg_iovlen = 1;
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
oldfs = get_fs();
set_fs(KERNEL_DS);
retval = sock_sendmsg(newsock, &msg, strlen(string)+1);
set_fs(oldfs);
return 0;
}
static void __exit server_module_exit( void ) {
printk(KERN_INFO "Exit usocket.");
}
module_init( server_module_init );
module_exit( server_module_exit );
MODULE_LICENSE("GPL");
Module Client
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/un.h>
#include <linux/net.h>
#include <net/sock.h>
#include <linux/socket.h>
#define SOCK_PATH "/tmp/usocket"
#define MAX 100
struct socket *sock = NULL;
static int __init client_module_init( void ) {
int retval;
char str[MAX];
struct sockaddr_un addr;
struct msghdr msg;
struct iovec iov;
mm_segment_t oldfs;
printk(KERN_INFO "Start client module.\n");
// create
retval = sock_create(AF_UNIX, SOCK_STREAM, 0, &sock);
// connect
memset(&addr, 0, sizeof(addr));
addr.sun_family = AF_UNIX;
strcpy(addr.sun_path, SOCK_PATH);
retval = sock->ops->connect(sock, (struct sockaddr *)&addr, sizeof(addr), 0);
// recvmsg
memset(&msg, 0, sizeof(msg));
memset(&iov, 0, sizeof(iov));
msg.msg_name = 0;
msg.msg_namelen = 0;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_iov->iov_base= str;
msg.msg_iov->iov_len= strlen(str)+1;
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
oldfs = get_fs();
set_fs(KERNEL_DS);
retval = sock_recvmsg(sock, &msg, strlen(str)+1, 0);
set_fs(oldfs);
// print str
printk(KERN_INFO "client module: %s.\n",str);
// release socket
sock_release(sock);
return 0;
}
static void __exit client_module_exit( void )
{
printk(KERN_INFO "Exit client module.\n");
}
module_init( client_module_init );
module_exit( client_module_exit );
MODULE_LICENSE("GPL");
User Server
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#define SOCK_PATH "/tmp/usocket"
int send_msg_to_client(int socketfd, char* data) {
struct msghdr msg;
struct iovec iov;
int s;
memset(&msg, 0, sizeof(msg));
memset(&iov, 0, sizeof(iov));
msg.msg_name = NULL;
msg.msg_namelen = 0;
iov.iov_base = data;
iov.iov_len = strlen(data)+1;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
s = sendmsg(socketfd, &msg, 0);
printf("after send - iov_base: %s, length: %d\n", (char *) msg.msg_iov->iov_base, (int) strlen(msg.msg_iov->iov_base));
if(s < 0){
perror("sendmsg");
return 0;
}
return s;
}
int main(int argc, char* argv[])
{
if (argc != 2) {
printf("Usage: $ %s <string>\n",argv[0]);
return 0;
}
int s, s2, len, slen;
socklen_t t;
struct sockaddr_un local, remote;
char* data = argv[1];
printf("print data: %s\n",data);
if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
perror("socket");
exit(1);
}
memset(&local, 0, sizeof(local));
local.sun_family = AF_UNIX;
strcpy(local.sun_path, SOCK_PATH);
unlink(local.sun_path);
len = strlen(local.sun_path) + sizeof(local.sun_family);
if (bind(s, (struct sockaddr *)&local, len) == -1) {
perror("bind");
exit(1);
}
if (listen(s, 5) == -1) {
perror("listen");
exit(1);
}
printf("Waiting for a connection...\n");
t = sizeof(remote);
if ((s2 = accept(s, (struct sockaddr *)&remote, &t)) == -1) {
perror("accept");
exit(1);
}
printf("Connected.\n");
slen = send_msg_to_client(s2, data);
if(slen < 0)
perror("send");
close(s2);
return 0;
}
User Client
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#define SOCK_PATH "/tmp/usocket"
#define MAX 100
int recv_msg_from_server(int socketfd, char data[MAX]) {
struct msghdr msg;
struct iovec iov;
int s;
memset(&msg, 0, sizeof(msg));
memset(&iov, 0, sizeof(iov));
msg.msg_name = NULL;
msg.msg_namelen = 0;
iov.iov_base = data;
iov.iov_len = MAX;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
s = recvmsg(socketfd, &msg, 0);
printf("after recv - iov_base: %s, length: %d\n", (char *) msg.msg_iov->iov_base, (int) strlen(msg.msg_iov->iov_base));
if(s < 0){
perror("recvmsg");
}
return s;
}
int main(void)
{
int s, len, slen;
struct sockaddr_un remote;
char data[MAX];
if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
perror("socket");
exit(1);
}
printf("Trying to connect...\n");
memset(&remote, 0, sizeof(remote));
remote.sun_family = AF_UNIX;
strcpy(remote.sun_path, SOCK_PATH);
len = strlen(remote.sun_path) + sizeof(remote.sun_family);
if (connect(s, (struct sockaddr *)&remote, len) == -1) {
perror("connect");
exit(1);
}
printf("Connected.\n");
slen = recv_msg_from_server(s, data);
if (slen < 0) {
perror("recvmsg");
}
//printf("print data received > %s\n", data);
close(s);
return 0;
}
I have just faced a similar issue (with UNIX datagrams though), and I believe there is a bug in the unix_mkname() function which is part of the kernel: this function makes sure the sun_path field of the given sockaddr_un structure is always null terminated by adding a NUL character after the end of that field. Since this is the last field, it will corrupt the area (stack or heap) where that structure has been allocated.
The best solution is to patch that function in the kernel source code, so that it only sets to NUL the last character of the sun_path field. Meanwhile, you can make your code work by decreasing by 1 byte the size you give for the sockaddr_un structure:
Module Server
// bind
retval = sock->ops->bind(sock,(struct sockaddr *)&addr, sizeof(addr) - 1);
Module Client
retval = sock->ops->connect(sock, (struct sockaddr *)&addr, sizeof(addr) - 1, 0);
As I am using UNIX datagrams, I cannot really tell if it fixes the issue for bind() and connect(), but a least, it fixes it for sock_sendmsg().
#shu-suzuki: thanks for the leads.
After 5 years I came back here...
I again stucked with this problem and found that I did the same thing 5 years ago.
The cause is as in Tey's answer and the solution is OK (sutbract 1 from the length) but here's another solution.
What you can do is to use struct sockaddr_storage as struct sockaddr_un. As far as I read the kernel code this is what they use to handle bind system call from user space.
sockeaddr_storage is larger than sockaddr_un so kernel code can write beyond the sizeof(sockaddr_un).
The code should be like
struct sockaddr_storage addrStorage;
struct sockaddr_un* addr;
memset(&addrStorage, 0, sizeof(addrStorage));
addr = (struct sockaddr_un*)&addrStorage;
addr->sun_family = AF_UNIX;
strcpy(addr->sun_path, "/my/sock/name");
kernel_bind(listenSock, (struct sockaddr*)addr, sizeof(*addr));
This looks working for me.
I am trying to run a simple IOCTL example on Android. I am using kernel 2.6 and ICS. The module is properly registered/unregistered (insmod/rmmod). However, every time a try to execute ./user_app on the emulator, I always get
error: first ioctl: Not a typewriter
error: second ioctl: Not a typewriter
message: `�
This is clearly a ENOTTY. I debugged the application, and no fops procedure (device_ioctl, read_ioctl and write_ioctl) is being executed.
I would like to know if there is any restriction with the usage/implementation of IOCTL on Android. Thank you very much in advance.
--Raul
Here is the code:
module.c
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <asm/uaccess.h>
#define MY_MACIG 'G'
#define READ_IOCTL _IOR(MY_MACIG, 0, int)
#define WRITE_IOCTL _IOW(MY_MACIG, 1, int)
int main(){
char buf[200];
int fd = -1;
if ((fd = open("/data/local/afile.txt", O_RDWR)) < 0) {
perror("open");
return -1;
}
if(ioctl(fd, WRITE_IOCTL, "hello world") < 0)
perror("first ioctl");
if(ioctl(fd, READ_IOCTL, buf) < 0)
perror("second ioctl");
printf("message: %s\n", buf);
return 0;
}
user_app.c
#include <stdio.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#define MY_MACIG 'G'
#define READ_IOCTL _IOR(MY_MACIG, 0, int)
#define WRITE_IOCTL _IOW(MY_MACIG, 1, int)
static char msg[200];
static ssize_t device_read(struct file *filp, char __user *buffer, size_t length, loff_t *offset)
{
...
}
static ssize_t device_write(struct file *filp, const char __user *buff, size_t len, loff_t *off)
{
...
}
char buf[200];
int device_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) {
int len = 200;
switch(cmd) {
case READ_IOCTL:
...
break;
case WRITE_IOCTL:
...
break;
default:
return -ENOTTY;
}
return len;
}
static struct file_operations fops = {
.read = device_read,
.write = device_write,
.unlocked_ioctl = device_ioctl,
};
static int __init example_module_init(void)
{
printk("registering module");
return 0;
}
static void __exit example_module_exit(void)
{
printk("unregistering module");
}
module_init(example_module_init);
module_exit(example_module_exit);
MODULE_LICENSE("GPL");
It this the whole code that you've posted? You don't register a char device when initializing a module, so this can't work.
Also, be carefull when assigning IOCTLS numbers. When using reserved IOCTL on a wrong file, you will get ENOTTY. Consult this to make sure you don't have conflicts.
Read more about char drivers here.
I changed ffmpeg.c according following link:
http://www.roman10.net/how-to-port-ffmpeg-the-program-to-androidideas-and-thoughts/
He said the change main () to JNI interface prototype. Well, I'm not familiar with JNI interface prototype, but I read an article about JNI and change it accordingly.
Can anyone look at my code to see is this true or not?
JNIEXPORT jint JNICALL Java_com_ffmpegtest_MainActivity_main(JNIEnv *pEnv, int argc, char **argv) {
int64_t ti;
av_log_set_flags(AV_LOG_SKIP_REPEATED);
if(argc>1 && !strcmp(argv[1], "-d")){
run_as_daemon=1;
verbose=-1;
av_log_set_callback(log_callback_null);
argc--;
argv++;
}
avcodec_register_all();
#if CONFIG_AVDEVICE
avdevice_register_all();
#endif
#if CONFIG_AVFILTER
avfilter_register_all();
#endif
av_register_all();
#if HAVE_ISATTY
if(isatty(STDIN_FILENO))
avio_set_interrupt_cb(decode_interrupt_cb);
#endif
init_opts();
if(verbose>=0)
show_banner();
/* parse options */
parse_options(argc, argv, options, opt_output_file);
if(nb_output_files <= 0 && nb_input_files == 0) {
show_usage();
fprintf(stderr, "Use -h to get full help or, even better, run 'man ffmpeg'\n");
ffmpeg_exit(1);
}
/* file converter / grab */
if (nb_output_files <= 0) {
fprintf(stderr, "At least one output file must be specified\n");
ffmpeg_exit(1);
}
if (nb_input_files == 0) {
fprintf(stderr, "At least one input file must be specified\n");
ffmpeg_exit(1);
}
ti = getutime();
if (transcode(output_files, nb_output_files, input_files, nb_input_files,
stream_maps, nb_stream_maps) < 0)
ffmpeg_exit(1);
ti = getutime() - ti;
if (do_benchmark) {
int maxrss = getmaxrss() / 1024;
printf("bench: utime=%0.3fs maxrss=%ikB\n", ti / 1000000.0, maxrss);
}
return ffmpeg_exit(0);
}
Should be
JNIEXPORT jint JNICALL
Java_com_ffmpegtest_MainActivity_main(JNIEnv *pEnv, jobject obj) {
where obj is the object of which this function is a member, i.e. your MainActivity instance. If you need to pass extra arguments, you'll need to add them to the native method declaration in the Java code as well.