Printing from a process spawned from a service on Windows 2008 server - c++

Question

The short version:
I have written a small program to print a report. This program is exec'ed from our proprietary server, that is running as a windows service. It works in our development environment, but not on our customer's network.
When I attempt to access the printing system in the failing case, I get a "No default printer" error. We had the customer create a new login account that has a default printer defined, and restarted the server using that login account. Same error.
Note that this error is generated when trying to find a specified printer, not when we try to print to it.
Is there any way to convince a server-spawned process that printers do, in fact, exist?
The long version:
In our "current" production environment, we have the following:
1. a proprietary server that runs as a service under windows.
2. a desktop client
--> accesses data via that service
--> uses fastreport4 to generate reports
--> developed using C++Builder6 (and VCL)
3. a PocketPC-based application that runs on scanning devices
--> uses Apache to communicate with the service
--> also uses Apache to poke a cgi-bin application that will bring up
the desktop app in stealth mode, run a report, and print it.
I have been tasked with re-implementing the Pocket-PC functionality on an Android-based scanning device, and removing the Apache layer from the architecture. In the Android app, I've written a communication layer to access the server (service) directly (the same way the desktop does). The server has the ability to exec applications, so I've written a small one to just gather data, and call fastreport to format and print it.
Works great. No problem. ... in our development environment. It works in our office network with the server running on a Windows 7 system. It works when run from the command line on our customer's Windows 2008 server. It does not work when run from the service on the customer's server.
So here's the code. In my current revision, I have try/catch and debug print statements around (nearly) every line of code. I removed them for readability.
bool __fastcall TFormReportRunner::mySetPrinter(const char* name)
{
char pDevice[MAX_PATH];
char pDriver[MAX_PATH];
char APort[100];
UINT ADeviceMode;
bool printerFound = false;
bool errorFound = false;
String PrinterPort = String(name).UpperCase();
TPrinter* Prntr;
// I added this bit to see if it helps. Seems to make no difference
bool rc = SetDefaultPrinter("");
Prntr = Printer();
if (Prntr == NULL)
{
LogErrorMsg("Printer() returned null.");
return false;
}
int i = Prntr->Printers->Count - 1;
for (; i >= 0; i--)
{
// In the failing case, this next statement is the one that causes an exception.
Prntr->PrinterIndex = i;
Prntr->GetPrinter(pDevice, pDriver, APort, ADeviceMode);
DWORD SizeNeeded = 0;
HANDLE PrinterHandle;
if (OpenPrinter(pDevice, &PrinterHandle, NULL) == 0)
{
LogErrorMsg("Could not open printer");
return false;
}
GetPrinter(PrinterHandle, 2, NULL, 0, &SizeNeeded);
if (SizeNeeded == 0)
{
ClosePrinter(PrinterHandle);
LogErrorMsg("Could not retrieve printer info size");
return false;
}
PRINTER_INFO_2 PrinterInfo2;
char* buffer = new char[SizeNeeded];
if (GetPrinter(PrinterHandle, 2, buffer, SizeNeeded, &SizeNeeded) == 0)
{
ClosePrinter(PrinterHandle);
delete [] buffer;
LogErrorMsg("Could not retrieve printer info");
return false;
}
String PortName = ((PRINTER_INFO_2*)buffer)->pPortName;
delete [] buffer;
ClosePrinter(PrinterHandle);
if (PrinterPort == PortName)
{
frxReport1->PrintOptions->Printer = pDevice;
break;
}
}
Prntr->PrinterIndex = i;
return true;
}
One of the customer's IT guys says that in order to have the Apache version work they have to run Apache as administrator with a defined default printer AND have that admin account logged in for printing to work. He suspects that if we run our service in the same configuration it will start to work. I have not been able to replicate that on our network. My admin account always works, whether anyone is currently logged into the system, or not. But this is Windows 7/Professional, and not a server version.
This has got to be possible... Apache's doing it. If it can find a printer and print to it, I should be able to, right?
Any hints or help will be greatly appreciated. Anything. Really. :)
Thanks,
-Karen
Edit: Adding server-side code.
A couple of notes, first. One, this was written 20-ish years ago (by someone else). Two, it is NOT a VCL app (and was compiled with the Microsoft compiler). Three, we will not change it. Recompiling with current compilers is WAY too risky for something that is otherwise working.
int myServer::RunProcess2(ClientCall *call, vector<string> &args, vector<string> &env, const char* input, unsigned int insize,
string *output, string *error)
{
CancelProcess2(); // only one process allowed per connection
string cmdline;
for (unsigned int i = 0; i < args.size(); i++)
{
if (i != 0)
cmdline += ' ';
cmdline += args[i];
}
env.push_back(EnvPATH);
int size = 1;
for (unsigned int i = 0; i < env.size(); i++)
{
size += env[i].size() + 1;
}
char *environment = (char*)malloc(size);
if (environment == NULL)
{
call->error = "Could not allocate memory for process environment variables";
return 0;
}
char *ptr = environment;
for (unsigned int i = 0; i < env.size(); i++)
{
size = env[i].size() + 1;
memcpy(ptr, env[i].c_str(), size);
ptr += size;
}
ptr[0] = '\0';
HANDLE hInputReadPipe = NULL, hInputWritePipe = NULL;
HANDLE hReadPipe, hWritePipe;
HANDLE hErrorReadPipe, hErrorWritePipe;
SECURITY_ATTRIBUTES sa;
sa.nLength = sizeof(sa);
sa.lpSecurityDescriptor = NULL;
sa.bInheritHandle = true;
// create output pipe
if (CreatePipe(&hReadPipe, &hWritePipe, &sa, 4096) == 0)
{
free(environment);
call->error = "Error creation Pipe";
return 0;
}
// create error pipe
if (CreatePipe(&hErrorReadPipe, &hErrorWritePipe, &sa, 4096) == 0)
{
CloseHandle(hReadPipe);
CloseHandle(hWritePipe);
free(environment);
call->error = "Error creating Pipe";
return 0;
}
if (insize > 0)
{
// create input pipe
if (CreatePipe(&hInputReadPipe, &hInputWritePipe, &sa, 4096) == 0)
{
CloseHandle(hReadPipe);
CloseHandle(hWritePipe);
CloseHandle(hErrorReadPipe);
CloseHandle(hErrorWritePipe);
free(environment);
call->error = "Error creating Pipe";
return 0;
}
}
STARTUPINFO si;
memset(&si, 0, sizeof(si));
si.cb = sizeof(si);
si.dwFlags = STARTF_USESHOWWINDOW | STARTF_USESTDHANDLES;
si.wShowWindow = SW_HIDE;
si.hStdOutput = hWritePipe;
si.hStdError = hErrorWritePipe;
si.hStdInput = hInputReadPipe;
PROCESS_INFORMATION pi;
if (CreateProcess(NULL, (char*)cmdline.c_str(), NULL, NULL, true, 0, environment, NULL, &si, &pi) == 0)
{
CloseHandle(hErrorReadPipe);
CloseHandle(hErrorWritePipe);
CloseHandle(hReadPipe);
CloseHandle(hWritePipe);
if (hInputReadPipe != NULL)
{
CloseHandle(hInputReadPipe);
CloseHandle(hInputWritePipe);
}
free(environment);
call->error = string("Error executing command: ") + cmdline + "\n" + GetErrorText();
return 0;
}
report_handle = pi.hProcess;
CloseHandle(hErrorWritePipe);
CloseHandle(hWritePipe);
if (hErrorReadPipe != NULL)
CloseHandle(hInputReadPipe);
char buffer[4097];
DWORD BytesAvail;
DWORD BytesRead = 0;
DWORD BytesWritten = 0;
DWORD BytesToRead = sizeof(buffer) - 1;
DWORD BytesToWrite = insize;
bool finished_readpipe = false, finished_errorpipe = false;
bool finished_inputpipe = (insize == 0);
int wait_time = 1;
bool error_occurred = false;
while (finished_readpipe == false || finished_errorpipe == false || finished_inputpipe == false)
{
if (finished_inputpipe == false)
{
if (BytesToWrite <= 0)
{
CloseHandle(hInputWritePipe);
hInputWritePipe = NULL;
finished_inputpipe = true;
continue;
}
BytesAvail = 1000;
/*if (PeekNamedPipe(hInputWritePipe, NULL, NULL, NULL, &BytesAvail, NULL) == 0)
{
DWORD temp = GetLastError();
// pipe has been closed
finished_inputpipe = true;
continue;
}*/
if (BytesAvail > 0)
{
if (BytesAvail > BytesToWrite)
BytesAvail = BytesToWrite;
if (WriteFile(hInputWritePipe, input, BytesAvail, &BytesWritten, NULL) == 0)
{
if (GetLastError() == ERROR_NO_DATA)
{
int a = 2; // Pipe was closed (normal exit path).
}
finished_inputpipe = true;
continue;
}
input += BytesWritten;
BytesToWrite -= BytesWritten;
if (BytesToWrite == 0)
{
finished_inputpipe = true;
}
continue;
}
}
if (finished_readpipe == false)
{
while (true)
{
if (PeekNamedPipe(hReadPipe, NULL, NULL, NULL, &BytesAvail, NULL) == 0)
{
// pipe has been closed
finished_readpipe = true;
break;
}
if (BytesAvail <= 0)
break;
if (BytesAvail > sizeof(buffer) - 1)
BytesAvail = sizeof(buffer) - 1;
if (ReadFile(hReadPipe, buffer, BytesAvail, &BytesRead, NULL) == 0)
{
finished_readpipe = true;
break;
}
if (BytesRead == 0)
{
finished_readpipe = true;
break;
}
buffer[BytesRead] = '\0';
*output += buffer;
if (output->length() >= MAX_PROCESS_OUTPUT)
{
finished_inputpipe = true;
finished_readpipe = true;
finished_errorpipe = true;
error_occurred = true;
call->error = "Output limit reached";
}
}
if (finished_readpipe == true)
continue;
}
if (finished_errorpipe == false)
{
while (true)
{
if (PeekNamedPipe(hErrorReadPipe, NULL, NULL, NULL, &BytesAvail, NULL) == 0)
{
// pipe has been closed
finished_errorpipe = true;
break;
}
if (BytesAvail <= 0)
break;
if (BytesAvail > sizeof(buffer) - 1)
BytesAvail = sizeof(buffer) - 1;
if (ReadFile(hErrorReadPipe, buffer, BytesAvail, &BytesRead, NULL) == 0)
{
finished_errorpipe = true;
break;
}
if (BytesRead == 0)
{
finished_errorpipe = true;
break;
}
buffer[BytesRead] = '\0';
*error += buffer;
if (error->length() >= MAX_PROCESS_OUTPUT)
{
finished_inputpipe = true;
finished_readpipe = true;
finished_errorpipe = true;
error_occurred = true;
call->error = "Error output limit reached";
}
}
if (finished_errorpipe == true)
continue;
}
// don't tie up the server
if (wait_time < 100)
wait_time++;
Sleep(wait_time);
}
if (error_occurred == false)
WaitForSingleObject(pi.hProcess, INFINITE);
process_mutex.lock();
report_handle = NULL;
process_mutex.unlock();
DWORD exit_code = 0;
GetExitCodeProcess(pi.hProcess, &exit_code);
CloseHandle(pi.hThread);
CloseHandle(pi.hProcess);
CloseHandle(hReadPipe);
CloseHandle(hErrorReadPipe);
if (hInputWritePipe != NULL)
CloseHandle(hInputWritePipe);
free(environment);
return exit_code;
}