Create process and anonymous pipe - c

Question

UPDATE Question: So I have been able to create the process and get the programs to compiled. However, I run into a new problem. When I try to pipe the Source program into the Filter program. It doesn't seem to feed in any input for the sink program. There are no error message. I have also test all of my standalone program using the pipe operator in Windows' cmd.
I'm trying to do this small project to learn about anonymous pipe and create process. I created 3 small standalone programs called Source, Filter, and Sink. These 3 are already compiled and run fine. Here's the descriptions for the 3 standalone programs.
Source: obtains a source text-file filename from its commandline, opens the file,and reads and copies the file contents one character at a time directly to standard output(stdout). When the file has been copied, Source terminates (closing all of its open file handles).
Filter program does not utilize any filename commandline parameters. Instead, Filter reads a text file from standard input (stdin) and writes to standard output (stdout) a copy of the input with all upper-case letters converted to lower-case. Filter specifically must be designed to read one character, convert it, output it, and then loop until the incoming data is finished.
Sink program obtains a destination text-file filename from its commandline, opens the file for writing, and then reads characters one at a time from the standard input file (stdin) and writes each incoming character directly to the destination sink file.
Next I'm driving a main driver program separately that creates 2 pipes and spawn 3 independent child with inputs and outputs configured to carry out the indicated concurrent execution and dataflow. Something like this:
srcfile -> Source -> pipe1 -> Filter -> Pipe2 -> Sink -> destfile
The driver program will requires 2 command line parameters:
C:\> Driver.exe srcfile destfile
where srcfile is an existing data text-file, and destfile is the filename of a new destination file that is to be created by the Sink application.
Here's my code for the driver program. It's not finished yet. But I encountered a hiccup when trying to create a process for the Source program.
UPDATED CODE:
#include <windows.h>
#include <WinBase.h>
#include <stdio.h>
#define DELAY_A_WHILE() {volatile long j; for(j = 1; j< 10000; j++) ; }
int main(int argc, char *argv[])
{
HANDLE hPipeRead, hPipeWrite, hPipeRead2, hPipeWrite2;
STARTUPINFO StartupInfoSource;
STARTUPINFO StartupInfoFilter;
STARTUPINFO StartupInfoSink;
PROCESS_INFORMATION ProcInfoSource;
PROCESS_INFORMATION ProcInfoFilter;
PROCESS_INFORMATION ProcInfoSink;
SECURITY_ATTRIBUTES PipeAttributes;
SECURITY_ATTRIBUTES PipeAttributes2;
char cmdline[200];
PipeAttributes.nLength = sizeof(SECURITY_ATTRIBUTES);
PipeAttributes.lpSecurityDescriptor = NULL; //ignore
PipeAttributes.bInheritHandle = TRUE; //child can inherit
//Create first pipe
if (!CreatePipe(&hPipeRead, &hPipeWrite, &PipeAttributes, 0)) {
fprintf(stderr, "Error creating pipe: %d\n", GetLastError());
exit(1);
}
sprintf_s(cmdline, 200, "Source.exe %s", argv[1]);
printf("Create process: %s\n", cmdline);
GetStartupInfo(&StartupInfoSource);
StartupInfoSource.dwFlags = StartupInfoSource.dwFlags | STARTF_USESTDHANDLES;
//Mapping
StartupInfoSource.hStdInput = GetStdHandle(STD_INPUT_HANDLE);
StartupInfoSource.hStdOutput = hPipeWrite;
StartupInfoSource.hStdError = GetStdHandle(STD_ERROR_HANDLE);
if (!CreateProcess(
NULL, cmdline, NULL, NULL,
TRUE,
CREATE_NEW_CONSOLE, NULL, NULL,
&StartupInfoSource,
&ProcInfoSource))
{
fprintf(stderr, "Error creating child process: %d",GetLastError());
exit(1);
}
CloseHandle(hPipeWrite);
CloseHandle(ProcInfoSource.hProcess);
CloseHandle(ProcInfoSource.hThread);
PipeAttributes2.nLength = sizeof(SECURITY_ATTRIBUTES);
PipeAttributes2.lpSecurityDescriptor = NULL; //ignore
PipeAttributes2.bInheritHandle = TRUE; //child can inherit
//Create Second Pipe
if (!CreatePipe(&hPipeRead2, &hPipeWrite2, &PipeAttributes2, 0)) {
fprintf(stderr, "Error creating pipe: %d\n", GetLastError());
exit(1);
}
GetStartupInfo(&StartupInfoFilter);
StartupInfoFilter.dwFlags = StartupInfoFilter.dwFlags | STARTF_USESTDHANDLES;
//Mapping
StartupInfoFilter.hStdInput = hPipeRead;
StartupInfoFilter.hStdOutput = hPipeWrite2;
StartupInfoFilter.hStdError = GetStdHandle(STD_ERROR_HANDLE);
sprintf_s(cmdline, 200, "Filter.exe");
printf("Create process: %s\n", cmdline);
//Filter
GetStartupInfo(&StartupInfoFilter);
if (!CreateProcess(
NULL, cmdline, NULL, NULL,
TRUE,
CREATE_NEW_CONSOLE, NULL, NULL,
&StartupInfoFilter,
&ProcInfoFilter))
{
fprintf(stderr, "Error creating child process: %d", GetLastError());
exit(1);
}
// int exitStatus;
// GetExitCodeProcess(ProcInfoFilter.hProcess, &exitStatus);
CloseHandle(hPipeRead);
CloseHandle(hPipeWrite2);
CloseHandle(ProcInfoFilter.hProcess);
CloseHandle(ProcInfoFilter.hThread);
GetStartupInfo(&StartupInfoSink);
StartupInfoSink.dwFlags = StartupInfoSink.dwFlags | STARTF_USESTDHANDLES;
//Mapping
StartupInfoSink.hStdInput = hPipeRead2;
StartupInfoSink.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
StartupInfoSink.hStdError = GetStdHandle(STD_ERROR_HANDLE);
sprintf_s(cmdline, 200, "Sink.exe %s", argv[2]);
printf("Create process: %s\n", cmdline);
GetStartupInfo(&StartupInfoSink);
if (!CreateProcess(
NULL, cmdline, NULL, NULL,
TRUE,
CREATE_NEW_CONSOLE, NULL, NULL,
&StartupInfoSink,
&ProcInfoSink))
{
fprintf(stderr, "Error creating child process: %d", GetLastError());
exit(1);
}
CloseHandle(hPipeRead2);
CloseHandle(ProcInfoSink.hProcess);
CloseHandle(ProcInfoSink.hThread);
return 0;
}
The program compiles fine. However, when it try to creates the Process, it always fails and exits. The cmdline value when it parse in is "Source.exe test.txt", which is exactly what I used to execute my standalone Source program. Can someone explain why my CreateProcess fail? Is it because I parse in the wrong parameter?

Answer 1

The only problem I can see here is the possibility that Source.exe app is not located in the same directory where Driver.exe is located. I tried your code and it was the only case when CreateProcess failed.

Answer 2

I have figure out why. My project's property was using the Unicode character set. When I switch to Multi-byte character set it works fine.