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Update:: In other word: I want to launch another program in the manner of a shell on Windows.
Need a two way communication between parent and child process using c++ on Windows. The parent is my program and the child is a random console application (like mysql terminal).
It's been a couple days searching but couldn't find any working solution for Windows. Also MS documentations is not helping.
Here i got a sample code from a question asked three years ago. How can i translate the code to Microsoft specific api and use it on Windows?
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#define Read 0
#define Write 1
#define ParentRead read_pipe[1]
#define ParentWrite write_pipe[0]
#define ChildRead write_pipe[1]
#define ChildWrite read_pipe[0]
int main()
{
int data_processed;
/** Pipe for reading for subprocess */
int read_pipe[2];
/** Pipe for writing to subprocess */
int write_pipe[2];
char buffer[100];
memset(buffer, '\0', 100);
if (pipe(read_pipe) == 0 && pipe(write_pipe) == 0)
{
pid_t pid = fork();
if (pid == (pid_t)-1)
{
fprintf(stderr, "Fork failure");
exit(EXIT_FAILURE);
}
else if (pid == (pid_t)0) //Child process
{
close(Read);
close(Write);
close(ParentRead);
close(ParentWrite);
dup(ChildRead);
dup(ChildWrite);
execlp("cat", (char*)NULL);
exit(EXIT_FAILURE);
}
else { //Parent process
close(ChildRead);
close(ChildWrite);
write(ParentWrite, "abc", 3);
int r = read(ParentRead, buffer, 99);
printf("%d %d", r, errno);
puts(buffer);
}
}
exit(EXIT_SUCCESS);
}
New Update:
So based on this sample I wrote a modified version of the sample code and seems to be OK except that the redirected output is not what it's supposed to be. Here's the code:
#include <iostream>
#include <Windows.h>
#include <string>
HANDLE hSTD_IN_READ = NULL;
HANDLE hSTD_IN_WRITE = NULL;
HANDLE hSTD_OUT_READ = NULL;
HANDLE hSTD_OUT_WRITE = NULL;
void WriteToPipe(std::string);
void ReadFromPipe();
int main()
{
SECURITY_ATTRIBUTES sa;
std::cout << "\nStart of parent execution: ";
// Set the bInheritHandle flag so pipe handles are inherited.
sa.nLength = sizeof(SECURITY_ATTRIBUTES);
sa.bInheritHandle = TRUE;
sa.lpSecurityDescriptor = NULL;
// Create pip for child process stdout
if (!CreatePipe(&hSTD_OUT_READ, &hSTD_OUT_WRITE, &sa, 0)) {
std::cout << "Error: CreatePipe STDOUT.\n";
return -1;
}
// Ensure the read handle to the pipe for stdout is not inherited.
if (!SetHandleInformation(hSTD_OUT_READ, HANDLE_FLAG_INHERIT, 0)) {
std::cout << "Error: STD_OUT_READ CreatePipe.\n";
return -1;
}
// Create pipe for child process's stdin
if (!CreatePipe(&hSTD_IN_READ, &hSTD_IN_WRITE, &sa, 0)) {
std::cout << "Error: CreatePipe STDIN.\n";
return -1;
}
// Ensure the write handle to the pipe for STDIN is not inherited.
if (!SetHandleInformation(hSTD_IN_WRITE, HANDLE_FLAG_INHERIT, 0)) {
std::cout << "Error: STD_IN_WRITE CreatePipe.\n";
return -1;
}
// Create Child Process
STARTUPINFO si;
PROCESS_INFORMATION pi;
BOOL bSuccess = FALSE;
ZeroMemory(&pi, sizeof(PROCESS_INFORMATION));
ZeroMemory(&si, sizeof(STARTUPINFO));
// This structure specifies the STDIN and STDOUT handles for redirection.
si.cb = sizeof(STARTUPINFO);
si.hStdError = hSTD_OUT_WRITE;
si.hStdInput = hSTD_IN_READ;
si.hStdOutput = hSTD_OUT_WRITE;
si.dwFlags |= STARTF_USESTDHANDLES;
bSuccess = CreateProcess(TEXT("c:\\sqlite3.exe"), NULL, NULL, NULL, TRUE, 0, NULL, NULL, &si, &pi);
if (!bSuccess) {
std::cout << "Error in CreateProcess.\n";
return -1;
}
else {
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
}
// Now execute your command then read the child process's output.
WriteToPipe(".databases");
ReadFromPipe();
std::cout << "End of program.\n";
return 0;
}
void WriteToPipe(std::string buffer)
{
DWORD bWritten, BUFFSIZE = buffer.size();
BOOL bSuccess = FALSE;
bSuccess = WriteFile(hSTD_IN_WRITE, buffer.c_str(), BUFFSIZE, &bWritten, NULL);
if (!bSuccess)
std::cout << "WritetoPipe::Couldn't Write to std_in_write.\n";
// Close the pipe handle so the child process stops reading.
if (!CloseHandle(hSTD_IN_WRITE))
std::cout << "WriteToPipe::Couldn't close the handle after Writing to std_in_write.\n";
}
void ReadFromPipe()
{
DWORD bRead, bWritten;
const DWORD BUFFSIZE = 4096;
CHAR buffer[BUFFSIZE];
BOOL bSuccess = FALSE;
HANDLE hPARENT_STD_OUT = GetStdHandle(STD_OUTPUT_HANDLE);
for (;;) {
bSuccess = ReadFile(hSTD_OUT_READ, buffer, BUFFSIZE, &bRead, NULL);
if (!bSuccess || bRead == 0) {
std::cout << "ReadFromPipe::Exiting after ReadFile.\n";
break;
}
bSuccess = WriteFile(hPARENT_STD_OUT, buffer, BUFFSIZE, &bWritten, NULL);
if (!bSuccess) {
std::cout << "ReadFromPipe::Exiting after WriteFile.\n";
break;
}
}
}
And the output:
Start of parent execution: seq name file
--- --------------- ----------------------------------------------------------
0 main
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kƒw
kƒw ⁿδ/ ░δ/ (° M ╚╜M ΦÉM îM Ç ÉìM └ 3 6 9 5 7 \ ╨φ/ |δ/ πlƒw╢êM ¿δ/ \ αφ/ ^ ¼φ/ πiƒw╨φ/ áδ/ `ε/ ≥iƒw ┐M \ ^ ¿δ/ S - M A÷₧wÿêM ■≤₧wP¡└(p M h 1 6 2 2 ╠ ╔8 0 - 3 6 9 5 7 ╠ ╔8 1 4 - öfM 0 1 &▄₧w B· A÷₧w ÿêM c : ┘╥₧w@¡└( M ÉêM ╠ ╔ M ╠ ╔ê├M äM Ç ╨∞/ ╠ ╔φ/ Ä╘Γ á∞/
╬M \φ/ φ/ \φ/ ╠ ╔=· zφ/ M ÉêM ñÉM ≡∞/ Ç ë½w┬ǃwL |φ/ ÿêM └& ê╤M ╕∞/ / ówVE_■ dφ/ P╞ów ÿêM ÿêM ╕φ/ á∩/ ÿêM `M S B _ E tφ/ ,╟₧w ÿêM °∩/ @X#u M ÿêM ɱ/ SX#áwɱ/ ┐M DZ/ P P6*uá∩/ ÿêM WΓF┼CÑ■ ìεπ╙≡WΓF┼CÑ■ ìεπ╙≡ _╩╝H±/ ñU#u DZ/ t⌠/ ▒U#u
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┌S╙╫∞°/ Φå█ ┤°/ 8┌ .databas
