Why does TTYUSB0 port settings change my stdout settings as well - c++

I have an embedded Atmel ARM926 board that I created a usb serial ko to get data from an FTDI as USBtty0. This board also has a serial port DBGU which is used as the console terminal that normally runs at 230kb. When I config the USBtty0 port to the required 115kb, DBGU apparently changes to 115kb as well.
if( m_fdELMdev = open(m_ELMdevice, O_RDWR | O_NOCTTY )< 0)
{//error
}
else
{
// Configure the port
tcgetattr(m_fdELMdev, &dev_settings);
dev_settings.c_cflag |= B115200;
cfmakeraw(&dev_settings);
}
Can someone please tell me what I might be doing wrong?
This is snippet of my devices.tab
/dev/tty c 640 0 0 4 0 0 1 4
/dev/tty c 640 0 0 5 0 - - -
/dev/ttyGS c 640 0 0 252 0 - - -
/dev/ttyS c 640 0 0 4 64 0 1 3
/dev/watchdog c 640 0 0 10 130 - - -
/dev/zero c 640 0 0 1 5 - - -
/dev/ttyACM0 c 640 0 0 166 0 - - -
/dev/ttyUSB0 c 640 0 0 188 0 - - -
Also, I occasionally see some 'Interrupted System Calls' from select. How do I need to handle these? Do I retry the select until I get some data? Then what if I never get any data?
enter code here
do
{
iret = select(m_fdELMdev + 1, &fdrefid, NULL, NULL, &porttime);
switch(iret)
{
case READ_TIMEOUT:
ierr = -1;
break;
case READ_ERROR:
g_dbg->debug("CACS_Elm327::Select error:%s (%d)\n",strerror(errno), errno);
ierr = -1;
break;
default:
iret = read(m_fdELMdev, data, ilen);
g_dbg->debug("CACS_Elm327::Readport_ELM:read %s %d\n", data, iret );
break;
}
}while((ierr == 0) && (iret<ilen) );

Related

Readfile API not reading anything while reading we are getting buffer as empty

Here is some details
Note:- All command are working fine with OSCALL function in compiler VC12
with complier VC14
exe name is RemDicomNodes.exe
CMD command prompt:-
RemDicomNodes 5 6 1 2 3 10 8 9
RemDicomNodes.exe 1 A
RemDicomNodes 2 B B 0 localhost 1 "BE" 104 3 1 7 7 60 0 "" 2 0 0 0 0 "" 3 0 0 0 0 "" 0 6 1 2 3 10 8 9 0 0 0 0 NoConversion 0 0 0 0 1 0 0 1 BE 0 0 0 IPv4 0 0 10 0 1 0
Above all commands are working fine and showing proper output on CMD command prompt
With OSCAll function:-
RemDicomNodes 5 6 1 2 3 10 8 9
#(Working fine i am getting output in variable "outputbuffer" which i am using inside readfile API)
RemDicomNodes.exe 1 A
#(Working fine i am getting output in variable "outputbuffer" which i am using inside readfile API)
RemDicomNodes.exe 2 B B 0 localhost 1 """BE"""" " 104 3 1 7 7 60 0 " """""" " 2 0 0 0 0 " """""" " 3 0 0 0 0 " """"""" 0 6 1 2 3 10 8 9 0 0 0 0 NoConversion 0 0 0 0 1 0 0 0 AE 0 0 0 IPv4 0 0 10 0 1 0"
#Problem(that any arguments we are send but it is not working, i am not getting output in variable "outputbuffer" which i am using inside readfile API it is not printing anything )
This is the function which i am using to run my exe
BOOL MagicWatchComProc::OSCall(CString i_cmd, CString& a_output, DWORD& a_exitCode, long i_timeOut)
{
STARTUPINFO aStartupInfo;
PROCESS_INFORMATION aProcessInfo;
HANDLE hReadHandle = NULL;
HANDLE hWriteHandle = NULL;
HANDLE hErrorHandle = NULL;
DWORD dwBytesRead = 0;
SECURITY_ATTRIBUTES sa = {sizeof(SECURITY_ATTRIBUTES), NULL, TRUE};
//time_t l_timeOut = 300000; //5 min.
//reset output string
a_output = "";
DEBUG_TRACE(_T("OSCall: launching ") + i_cmd);
if (!i_cmd)
{
DEBUG_TRACE(_T("OSCall: Error: empty command\n"));
return false;
}
//reset errors
SetLastError(0);
// Initialize process startup structure
FillMemory(&aStartupInfo, sizeof(aStartupInfo), 0);
//GetStartupInfo(&aStartupInfo);
aStartupInfo.cb = sizeof(aStartupInfo);
aStartupInfo.dwFlags = STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
aStartupInfo.wShowWindow = SW_HIDE;
// Create pipe that will transfer the process output to our buffer
if(!CreatePipe(&hReadHandle, &hWriteHandle, &sa, 0))
{
DEBUG_TRACE(_T("OSCall: Error: Pipe creation\n"));
return false;
}
// Set process' stdout to our pipe
aStartupInfo.hStdOutput = hWriteHandle;
// We are going to duplicate our pipe's write handle
// and pass it as stderr to create process. The idea
// is that some processes have been known to close
// stderr which would also close stdout if we passed
// the same handle. Therefore we make a copy of stdout's
// pipe handle.
if (!DuplicateHandle( GetCurrentProcess(), hWriteHandle, GetCurrentProcess(), &hErrorHandle, 0, TRUE, DUPLICATE_SAME_ACCESS ))
{
CloseHandle(hReadHandle);
CloseHandle(hWriteHandle);
DEBUG_TRACE(_T("OSCall: Error: duplicate handle\n"));
return false;
}
aStartupInfo.hStdError = hErrorHandle;
// Check input parameter
TCHAR l_inputCommand[2048];
_tcscpy(l_inputCommand, i_cmd);
// Create process of service program
if(!CreateProcess( NULL, l_inputCommand, NULL, NULL, TRUE, CREATE_NEW_CONSOLE, NULL, NULL, &aStartupInfo, &aProcessInfo ))
{
CloseHandle(hReadHandle);
CloseHandle(hWriteHandle);
CloseHandle(hErrorHandle);
DEBUG_TRACE(_T("OSCall: Error: could not create process\n"));
return false;
}
// The process is alive now and has inherited the environment, now
// we can release the critical section
// Close the write end of our pipe (both copies)
// so it will die when the child process terminates
CloseHandle(hWriteHandle);
CloseHandle(hErrorHandle);
// We close the handle of the process in order to prevent memory leaks when
// the process terminates.
//CloseHandle(aProcessInfo.hThread);
// Allocate memory for output buffer
DWORD dwAvailableOutput = 16;
CHAR outputbuffer[18];
//CString strPipeName;
//DWORD dwSize = 0;
//GetNamedPipeHandleState( hReadHandle, NULL, NULL, NULL, NULL, strPipeName.GetBuffer(1), dwSize );
//WaitNamedPipe( strPipeName, 100 );
// -> Read output from CGI program
time_t l_time;
time_t l_startTime;
time(&l_startTime);
do
{
time(&l_time);
if( (l_time - l_startTime) > i_timeOut)
{
SetLastError(WAIT_TIMEOUT);
break;
}
if( ReadFile( hReadHandle, outputbuffer, dwAvailableOutput, &dwBytesRead, NULL ) )
{
outputbuffer[dwBytesRead] = 0; // null terminate
a_output += outputbuffer;
}
}
//We are done
while ( GetLastError() != ERROR_BROKEN_PIPE );
//reset ERROR_BROKEN_PIPE error
if(GetLastError() == ERROR_BROKEN_PIPE)
SetLastError(0);
//DEBUG_TRACE(_T("OSCall: command output: ") + a_output);
//CloseHandle(hErrorHandle);
CloseHandle(hReadHandle);
if( !GetLastError() )
{
return true;
}
else
{
DEBUG_TRACE(_T("OSCall: Error: cmd command failed. Error code: ")+ i2cs(GetLastError()) +_T("; ExitCode: ")+ i2cs(a_exitCode) +_T("."));
return false;
}
}
int main()
{
DWORD dwExitCode = 0;
long l_timeOut = 60000; //ms = 10 min
BOOL bRet = FALSE;
CString strInstallLmutil(_T("cmd.exe /C "));
CString strLmutilInstallFile(_T("remdicomnodes.exe"));
CString strPathLmutilInstall;
strPathLmutilInstall.Format(_T("%s\\bin\\%s"),strtemp,strLmutilInstallFile);
strInstallOption = _T("");
strInstallOption = _T(" 2 B B 0 localhost 1 \"""BE""\"" " 104 3 1 7 7 60 0 " "\"""\"" " 2 0 0 0 0 " "\"""\"" " 3 0 0 0 0 " "\"""\""" 0 6 1 2 3 10 8 9 0 0 0 0 NoConversion 0 0 0 0 1 0 0 0 AE 0 0 0 IPv4 0 0 10 0 1 0");
bRet = OSCall ( cmd, l_commandOutput, dwExitCode, l_timeOut);
SAM_TRACE1("OSCall: bRet value: :%d ",bRet);
if( bRet == FALSE )
{
SAM_TRACE0("remdicomnodes.exe execution failed \n");
}
return 0;
}

shared memory segment can't be removed after call shmdt()

i called shmdt() successfully, but shared memory segment can't be removed..
this is my code:
#include <sys/types.h>
#include <sys/shm.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
int main() {
key_t key = ftok(".", 'T');
if (key == -1) {
fprintf(stderr, "get key failed, error: %s\n", strerror(errno));
exit(1);
}
int shmid = shmget(key, sizeof(int) * 10, IPC_CREAT);
if (shmid == -1) {
fprintf(stderr, "get shmid failed, error: %s\n", strerror(errno));
exit(1);
}
void* shmaddr = shmat(shmid, NULL, 0);
if (shmaddr == (void*)-1) {
fprintf(stderr, "get shmaddr failed, error: %s\n", strerror(errno));
exit(1);
}
if (shmdt(shmaddr) == -1) {
fprintf(stderr, "detach failed, error: %s\n", strerror(errno));
exit(1);
}
return 0;
}
after that, i execute ipcs -m
# ipcs -m
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 1179648 root 0 4 0
0x00000000 1212417 root 0 4 0
0x00000000 1245186 root 0 4 0
0x00000000 1277955 root 0 4 0
0x00000000 1310724 root 0 4 0
0x00000000 1343493 root 0 4 0
0x00000000 1376262 root 0 4 0
0x00000000 1409031 root 0 4 0
0x00000000 1441800 root 0 4 0
0x00000000 1474569 root 0 4 0
0x54010004 1671178 root 0 40 0
0x00000000 1540107 root 0 4 0
shmdt() detaches the shared memory segment located at the address
specified by shmaddr from the address space of the calling process.
The to-be-detached segment must be currently attached with shmaddr
equal to the value returned by the attaching shmat() call.
shmdt only detaches the calling process from attached memory. It will not remove the shared memory created by the process.
For more information please read the man page of the respective system calls.

Sudden receive-buffer buildup on CentOS for C++ application

I have a somewhat strange problem when receiving UDP data on CentOS. When my application receives data everything is fine at first and all packets are received as expected, then all of a sudden the kernel receive buffer (net.core.rmem) starts to fill up for no apparent reason until it's full and packets are dropped. The strange part is that the buffer is more or less empty until all of a sudden when it starts to increase dramatically even though the sending party sends at the same rate as before. As if a resource I haven't accounted for is depleted, or the operating system changes priority of the thread dedicated for receive operations. Data is still received and read by receive(), but the buffer starts to fill too fast.
Files are sent from the sending application to the receiving application. There is a unidirectional gateway between the sending and receiving application, so there is no possibility for congestion control (or TCP) what so ever. The problem only arises when I send a big file (around 3 GiB or more). Everything works fine when I send multiple small files, even if the sum of their size is much larger than 3 GiB.
At the moment I'm unable to specify the problem further and I'm pretty stunned as to what could be wrong. This is the information about the systems configuration that I can imagine being relevant, but I've looked into memory leaks, disk usage and buffer sizes without being able to find something specific.
Data is sent at a rate of 100 Mbit/s.
MTU is 9000 on both the sending and receiving machine.
net.core.rmem_max/net.core.rmem_default is set to 536870912 Bytes (huge).
net.core.netdev_max_backlog is set to 65536 (huge).
Each UDP packet sent is 8192 Bytes, excluding the UDP header.
A temporary file created through tmpfile() is used to store the data for each file.
The temporary file is closed as soon as the file is completed (hashsum is verified).
CPU usage when receiving files is consistent at 100%.
Memory usage when receiving files is consistent at 0.5%.
receive()
std::vector<uint8_t>* vector = new std::vector<uint8_t>();
while (signal == 0)
{
ret = _serverio->Receive(*vector);
if (ret == -1 || ret == 0)
{
continue;
}
else
{
Produce(vector);
vector = new std::vector<uint8_t>();
}
}
_serverio->Receive(std::vector& data)
ssize_t n;
data.resize(UDPMAXMSG);
int res = m_fdwait.Wait(m_timeoutms);
if(res < 1) {
data.resize(0);
return res; // timeout or interrupt
}
n = read(m_servfd, &(data[0]), data.size());
if(n < 0) {
if(errno == EINTR) {
data.resize(0);
return -1;
}
else {
throw socket_error(errno, "UDPServer::Receive");
}
}
data.resize(n);
return n;
Produce(std::vector* vector)
_producerSemaphore.aquire();
_queue.lock();
_buffer.push_back(vector);
_queue.unlock();
_consumerSemaphore.release();
Consume()
bool aquired = false;
while (!aquired)
{
if (_terminated)
{
// Consume should return NULL immediately if
// receiver has been terminated.
return NULL;
}
aquired = _consumerSemaphore.aquire_timeout(1);
}
std::vector<uint8_t>* vector = NULL;
_queue.lock();
vector = _buffer.front();
_buffer.pop_front();
_queue.unlock();
_producerSemaphore.release();
return vector;
recv_buffer.sh (for monitoring of the receive buffer)
while true ; do
_BUFFER_VALUE=$(printf "%d" "0x$(grep 2710 /proc/net/udp \
| awk '{print $5}' | sed 's/.*://')")
_DELTA=$(expr $_BUFFER_VALUE - $_PRE_BUFFER)
_PRE_BUFFER=$_BUFFER_VALUE
echo "$_BUFFER_VALUE : $_DELTA"
sleep 0.1
done
recv_buffer.sh output
buffer-size delta
0 0
0 0
...
10792 10792
10792 0
0 -10792
10792 10792
0 -10792
0 0
0 0
0 0 // This type of pattern goes on for 2.5 GiB
...
0 0
0 0
0 0
0 0
971280 971280 // At this point the buffer starts to fill
1823848 852568
1931768 107920
2039688 107920
2179984 140296
2287904 107920
2406616 118712
2525328 118712
2644040 118712
2741168 97128
2881464 140296
3010968 129504
3140472 129504
...
533567272 647520
536038640 2471368
536675368 636728
536880416 205048 // At this point packets are dropped
536869624 -10792
536880416 10792
536880416 0
536869624 -10792
536880416 10792
536869624 -10792
536880416 10792
536880416 0
536880416 0
536880416 0
536880416 0
536880416 0

How to fix timeout on rs232 serial port?

I have a problem when reading from the serial port.
The problem is that for the last 2 bytes ( CRC bytes ) read from an rs232 port the read waits until the timeout set in timeval ends, then returns. On rs485, with the same method used for reading, read returns fine. What I have seen while debbuging is that on rs485 there is an extra byte with value FF after the 2 CRC bytes. I can't find another difference between the 2.
Here are the relevant parts of code:
setting the port
bool Serial::setup(){
if(!openPort()){
return false;
}
tcgetattr(fdPort, &options);
cfsetispeed(&options, B115200);
cfsetospeed(&options, B115200);
options.c_cflag &= ~PARENB;
options.c_cflag &= ~CSTOPB;
options.c_cflag &= ~CSIZE;
options.c_cflag |= CS8;
options.c_cc[VMIN] = 0;
options.c_cc[VTIME] = 1;
options.c_oflag &= ~(OCRNL | ONLCR | ONLRET |
ONOCR | OFILL | OLCUC | OPOST);
options.c_iflag &= ~(IGNBRK | BRKINT | ICRNL | INLCR |
PARMRK | INPCK | ISTRIP | IXON) ;
options.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN | ISIG);
if(tcsetattr(this->fdPort, TCSANOW, &options)){
return false;
}
return true;
}
opening the port
bool Serial::openPort(){
this->fdPort = open(this->port, O_RDWR | O_NOCTTY | O_NDELAY | O_NONBLOCK);
if(fdPort == -1){
return false;
}
else{
//fcntl(fdPort, F_SETFL, 0);
//fcntl(fdPort, F_SETFL, FNDELAY);
}
int status = 0;
status |= TIOCM_RTS;
ioctl(this->fdPort, TIOCMSET, &status);
return true;
}
The wait frame where data is interpreted and read in chunks.
bool GlobalProtocol::WaitFrame(uint32_t timeOut) {
int32_t bytesRec = 0;
int32_t bytesToRec = 1;
int recPhase = GC_PHASE_START;
uint8_t *pData = m_RxBuff;
bool commSuccess = true;
m_LastError = boards::GCL_ERR_OK;
while (readData(pData, bytesToRec, &bytesRec, timeOut)) {
if (bytesRec) {
switch (recPhase) {
case GC_PHASE_START:
if (*pData != GC_START_FRAME_BYTE) {
continue;
}
recPhase++;
pData++;
break;
case GC_PHASE_DEST:
if (*pData != m_MasterAddr) {
commSuccess = false;
break;
}
recPhase++;
pData++;
break;
case GC_PHASE_SRC:
recPhase++;
pData++;
break;
case GC_PHASE_LEN_LO:
if (*pData < 2 || *pData > GC_MAX_COMM_DATA_LEN) {
commSuccess = false;
break;
}
recPhase++;
pData++;
break;
case GC_PHASE_LEN_HI:
if (*pData != 0) {
commSuccess = false;
break;
}
recPhase++;
pData++;
bytesToRec = m_RxBuff[GC_PHASE_LEN_LO];
break;
case GC_PHASE_DATA:
if (bytesRec != bytesToRec) {
commSuccess = false;
break;
}
recPhase++;
pData += bytesRec;
bytesToRec = 2;
break;
case GC_PHASE_CRC_LO:
if (bytesRec != bytesToRec) {
commSuccess = false;
break;
}
if (CheckCRC(m_RxBuff, m_RxBuff[GC_PHASE_LEN_LO] + GC_PHASE_DATA + sizeof(uint16_t))) {
m_RecAddr = m_RxBuff[GC_PHASE_SRC];
return true;
}
commSuccess = false;
break;
}
if (!commSuccess) break;
}
else break;
}
m_LastError = boards::GCL_ERR_ANSWERNOTREC;
return false;
}
And where the reading is done.
bool Serial::readData(uint8_t *data, uint32_t length, int32_t *receivedDataBytes, int32_t timeoutVal){
int32_t tempReceivedDataBytes = -1;
fd_set readFd;
FD_ZERO(&readFd);
FD_SET(fdPort, &readFd);
struct timeval timeout;
timeout.tv_sec = 0;
timeout.tv_usec = timeoutVal * 1000;
int test = 0;
uint32_t bytesAvail = 0;
QTime timer;
timer.start();
if(fcntl(fdPort, F_GETFD) != -1){
while(((test = select(this->fdPort + 1, &readFd, NULL, NULL, &timeout)) == 1) && (tempReceivedDataBytes == -1)){
ioctl(fdPort, FIONREAD, &bytesAvail);
if(FD_ISSET(fdPort, &readFd) && bytesAvail >= length){
tempReceivedDataBytes = read(fdPort, data, length);
}
if(timer.elapsed() > (timeoutVal + 5)){ //fail-safe
logger[debug_log] << "TIMEOUT" << endl;
break;
}
}
if(test == -1)
logger[debug_log]<< strerror(errno) << endl;
if(tempReceivedDataBytes < 0){
return false;
}
if(tempReceivedDataBytes >= 0){
*receivedDataBytes = tempReceivedDataBytes;
return true;
}
}
return false;
}
If I set the timeout to 100 ms, then it waits 100 ms to read the 2 bytes, if I set it to 10 ms, then it waits 10 ms to read the 2 bytes.
I tried changing the port settings, but with no success.
I have been trying to solve this for days but with no success.
Edit:
I should add that ioctl(fdPort, FIONREAD, &bytesAvail); is setting bytesAvail to 2, but read waits until timeout to read them.
Edit 2:
Here is a log with a timeout set to 25 seconds so you can get an idea of what's the problem:
04/17/2014 15:51:50:584,Main board start:
04/17/2014 15:51:50:586,1 Received 1 Needed to receive 1
04/17/2014 15:51:50:586,1 Received 1 Needed to receive 1
04/17/2014 15:51:50:586,1 Received 1 Needed to receive 1
04/17/2014 15:51:50:587,1 Received 1 Needed to receive 1
04/17/2014 15:51:50:587,1 Received 1 Needed to receive 1
04/17/2014 15:51:50:597,1 Received 110 Needed to receive 110
04/17/2014 15:51:50:597,1 Received 2 Needed to receive 2
04/17/2014 15:51:50:634,PID board start:
04/17/2014 15:51:50:635,1 Received 1 Needed to receive 1
04/17/2014 15:51:50:635,1 Received 1 Needed to receive 1
04/17/2014 15:51:50:635,1 Received 1 Needed to receive 1
04/17/2014 15:51:50:635,1 Received 1 Needed to receive 1
04/17/2014 15:51:50:635,1 Received 1 Needed to receive 1
04/17/2014 15:51:50:641,1 Received 70 Needed to receive 70
04/17/2014 15:52:15:647,0 Received 2 Needed to receive 2
04/17/2014 15:52:15:647,Set Leds board start:
04/17/2014 15:52:15:649,1 Received 1 Needed to receive 1
04/17/2014 15:52:15:649,1 Received 1 Needed to receive 1
04/17/2014 15:52:15:652,1 Received 1 Needed to receive 1
04/17/2014 15:52:15:652,1 Received 1 Needed to receive 1
04/17/2014 15:52:15:652,1 Received 1 Needed to receive 1
04/17/2014 15:52:15:652,1 Received 2 Needed to receive 2
04/17/2014 15:52:15:652,1 Received 2 Needed to receive 2
04/17/2014 15:52:15:652,Get state board start:
04/17/2014 15:52:15:654,1 Received 1 Needed to receive 1
04/17/2014 15:52:15:654,1 Received 1 Needed to receive 1
04/17/2014 15:52:15:654,1 Received 1 Needed to receive 1
04/17/2014 15:52:15:654,1 Received 1 Needed to receive 1
04/17/2014 15:52:15:655,1 Received 1 Needed to receive 1
04/17/2014 15:52:15:657,1 Received 30 Needed to receive 30
04/17/2014 15:52:15:657,1 Received 2 Needed to receive 2
The one with the problems is the PID board ( on a rs232), the others are on the same rs485.
And here is one with a timeout set to around 30 ms ( I can't remember the exact value):
04/17/2014 15:08:08:045,Main board start:
04/17/2014 15:08:08:046,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:046,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:046,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:047,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:047,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:056,1 Received 110 Needed to receive 110
04/17/2014 15:08:08:056,1 Received 2 Needed to receive 2
04/17/2014 15:08:08:078,PID board start:
04/17/2014 15:08:08:079,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:079,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:079,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:079,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:079,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:094,1 Received 70 Needed to receive 70
04/17/2014 15:08:08:120,0 Received 2 Needed to receive 2
04/17/2014 15:08:08:120,Set Leds board start:
04/17/2014 15:08:08:122,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:122,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:122,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:122,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:122,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:122,1 Received 2 Needed to receive 2
04/17/2014 15:08:08:122,1 Received 2 Needed to receive 2
04/17/2014 15:08:08:123,Get state board start:
04/17/2014 15:08:08:124,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:124,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:124,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:125,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:125,1 Received 1 Needed to receive 1
04/17/2014 15:08:08:128,1 Received 30 Needed to receive 30
04/17/2014 15:08:08:128,1 Received 2 Needed to receive 2
Edit: I still can't figure out what is wrong. If I remove the extra byte on rs485 it is the same. Here is another log:
06/24/2014 12:57:01:923,Set Leds board start:
06/24/2014 12:57:06:701,Select value 1 Received: 1 Needed: 1 Bytes available: 9
06/24/2014 12:57:06:701,Select value 1 Received: 1 Needed: 1 Bytes available: 8
06/24/2014 12:57:06:702,Select value 1 Received: 1 Needed: 1 Bytes available: 7
06/24/2014 12:57:06:702,Select value 1 Received: 1 Needed: 1 Bytes available: 6
06/24/2014 12:57:06:702,Select value 1 Received: 1 Needed: 1 Bytes available: 5
06/24/2014 12:57:06:702,Select value 1 Received: 2 Needed: 2 Bytes available: 4
06/24/2014 12:57:06:752,Select value 0 Received: 2 Needed: 2 Bytes available: 2
06/24/2014 12:57:06:752,Get state board start:
06/24/2014 12:57:06:754,Select value 1 Received: 1 Needed: 1 Bytes available: 4
06/24/2014 12:57:06:754,Select value 1 Received: 1 Needed: 1 Bytes available: 3
06/24/2014 12:57:06:754,Select value 1 Received: 1 Needed: 1 Bytes available: 2
06/24/2014 12:57:06:754,Select value 1 Received: 1 Needed: 1 Bytes available: 1
06/24/2014 12:57:06:755,Select value 1 Received: 1 Needed: 1 Bytes available: 10
06/24/2014 12:57:06:758,Select value 1 Received: 30 Needed: 30 Bytes available: 30
06/24/2014 12:57:06:808,Select value 0 Received: 2 Needed: 2 Bytes available: 2
06/24/2014 12:57:06:886,Main board start:
06/24/2014 12:57:06:888,Select value 1 Received: 1 Needed: 1 Bytes available: 3
06/24/2014 12:57:06:888,Select value 1 Received: 1 Needed: 1 Bytes available: 2
06/24/2014 12:57:06:889,Select value 1 Received: 1 Needed: 1 Bytes available: 1
06/24/2014 12:57:06:890,Select value 1 Received: 1 Needed: 1 Bytes available: 23
06/24/2014 12:57:06:890,Select value 1 Received: 1 Needed: 1 Bytes available: 22
06/24/2014 12:57:06:898,Select value 1 Received: 110 Needed: 110 Bytes available: 113
06/24/2014 12:57:06:898,Select value 1 Received: 2 Needed: 2 Bytes available: 3
As you can see when the number of available bytes is equal with the number of bytes to read it waits in the read function until timeout and then returns.
What hardware are you using? Real serial port or usb adapter? Some FTDI usb to serial adapters are configured so they send the bytes over usb in batches. That speeds up the transfer when the port is fully loaded but they behave like you mentioned when dealing with few bytes at a time.
I managed to fix it. It was a simple fix.
I had to replace while(((test = select(this->fdPort + 1, &readFd, NULL, NULL, &timeout)) == 1) && (tempReceivedDataBytes == -1))
with while( (tempReceivedDataBytes == -1) && ((test = select(this->fdPort + 1, &readFd, NULL, NULL, &timeout)) == 1))
.
If the serial buffer was empty it was waiting in select until timeout, even if it read something. If there was someting on the port it was checking the second part of the while and exiting it.
Set a non-zero value of VMIN, so that the read can be satisfied as soon as at least that many characters have been received.
This would mean that:
If no data has been buffered, the call will wait up to timeout for some data
If at least VMIN characters have been buffered, the call will return immediately with those, without waiting for the timeout.

Retrieving system calls with Ptrace, stopping after first one

I am trying to retrieve all of the numbers of system calls and eventually the names of the system calls called by a give program using ptrace. I am on a 64 bit system so I am using the ORIG_RAX * 8 to find system calls using ptrace. I currently can only retrieve the first system call, output of a sample run is below. Any ideas?
Thanks!
Output:
griffinm#well $ g++ mystrace.cc
~/cs153/assn2
griffinm#well $ a.out ls
Please wait
The child made a system call 59
a.out mystrace.cc mystrace.cc~
Number of machine instructions : 252376
~/cs153/assn2
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <errno.h>
#define ORIG_RAX 120
int main( int argc, char* argv[])
{
long long counter = 0; /* machine instruction counter */
int wait_val; /* child's return value */
int pid;
long orig_eax; /* child's process id */
puts("Please wait");
switch (pid = fork()) {
case -1:
perror("fork");
break;
case 0:
ptrace(PTRACE_TRACEME, 0, 0, 0);
execvp(argv[1], NULL);
break;
default:
wait(&wait_val);
orig_eax = ptrace(PTRACE_PEEKUSER,
pid, ORIG_RAX,
NULL);
printf("The child made a "
"system call %ld\n", orig_eax);
while (wait_val == 1407 ) {
counter++;
if (ptrace(PTRACE_SINGLESTEP, pid, 0, 0) != 0)
perror("ptrace");
wait(&wait_val);
}
}
printf("Number of machine instructions : %lld\n", counter);
return 0;
}
Update Default Case:
Default:
wait(&wait_val);
while (wait_val == 1407 ) {
counter++;
if (ptrace(PTRACE_SYSCALL, pid, 0, 0) != 0)
perror("ptrace");
orig_eax = ptrace(PTRACE_PEEKUSER,
pid, 8*ORIG_RAX,
NULL);
cout<<orig_eax<<endl;
wait(&wait_val);
}
}
Edit:
Output:
griffinm#well $ a.out pwd
Please wait
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
/home/csmajs/griffinm/cs153/assn2
-1
-1
-1
-1
-1
-1
I think the 8*Orig_RAX is the problem, the machine is 64 bit like I said. Any ideas?
You probably want to use PTRACE_SYSCALL instead of PTRACE_SINGLESTEP to run the child up to the next system call rather than just a single instruction. Then you can use the PTRACE_PEEKUSER again to see what syscall it is.