简短版本：
我写了一个小程序来打印报告。该程序是从我们作为Windows服务运行的专有服务器中执行的。它适用于我们的开发环境，但不适用于我们客户的网络。
在失败的情况下尝试访问打印系统时，出现“无默认打印机”错误。我们让客户创建了一个定义了默认打印机的新登录帐户，然后使用该登录帐户重新启动了服务器。同样的错误。
请注意，此错误是在尝试查找指定的打印机时生成的，而不是在我们尝试打印到该打印机时生成的。
有没有办法说服服务器产生的进程实际上确实存在打印机？
长版：
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.
我的任务是在基于Android的扫描设备上重新实现Pocket-PC功能，并从体系结构中删除Apache层。在Android应用程序中，我编写了一个通信层以直接访问服务器（服务）（与台式机相同）。该服务器具有执行应用程序的能力，因此我编写了一个小程序来收集数据，然后调用fastreport进行格式化和打印。
效果很好。没问题。 ...在我们的开发环境中。它可以在我们的办公室网络中运行，并且服务器可以在Windows 7系统上运行。当从客户的Windows 2008服务器上的命令行运行时，它可以工作。从客户服务器上的服务运行时，它不起作用。
所以这是代码。在当前的修订版中，我（几乎）每行代码都尝试/捕获和调试了打印语句。为了便于阅读，我将其删除。
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;
}
该客户的一位IT人士说，要使Apache版本正常工作，他们必须以管理员身份使用已定义的默认打印机运行Apache，并必须登录该管理员帐户才能进行打印。他怀疑如果我们以相同的配置运行我们的服务，它将开始起作用。我无法在我们的网络上复制它。无论当前是否有人登录系统，我的管理员帐户始终有效。但这是Windows 7 / Professional，而不是服务器版本。
这必须是可能的……Apache正在这样做。如果它可以找到打印机并进行打印，我应该可以，对吧？
任何提示或帮助将不胜感激。没事真。 :) 谢谢， -凯伦
编辑：添加服务器端代码。
首先要注意几个注意事项。其中之一是20年前写的（别人写的）。第二，它不是VCL应用程序（是使用Microsoft编译器编译的）。第三，我们不会改变它。对于当前可以正常运行的编译器，使用当前的编译器进行重新编译的风险太大。
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;
}