Creating an array of pipes.

[arkashkin]

Hi,
I have a specific number of processes, which were created using fork(), those processes should communicate each with other using pipes. I want to create a dynamic array of pipes or use a Vector so it would contain all the pipes there were created.

each pipe should be of size of 2 integers so the array of the vector size should be arr[N][2].

my problem is that I don't know how to create properly this Vector or Array and pass it correctly to the dup2 function.

Maybe some one could help me with an example?

I build those two functions:


int** createArrOfPipes(int amount)
{
int** arr = new int*[amount];

for (int i=0;i<amount;i++)
{
arr[i] = new int[2];
}

return arr;
}

void freeArrOfPipes(int** arr, int amount)
{
for (int i=0;i<amount;i++)
{
delete[] arr[i];
}
delete[] arr;
}


and tried to use vector, like this:

vector< vector<int> > pipes;
vector<int> read_vec1;
vector<int> write_vec2;
pipes.push_back(read_vec1);
pipes.push_back(write_vec2);


but how to do some thing like this:


for(int i=0;i<(sub_commands.size()-1);i++)
{
pipe(pipes[i]);
}


or this:


while (dup2 (pipes[(command_index-1)][read], STDIN_FILENO) < 0) //dup client's sock with stdin
{
if (errno == EINTR) continue;

fprintf(stderr,"dup2 failed.");
}

[dwhitney67]

Consider something like:


#include <vector>

const size_t N = 32;

struct Pipes
{
int rdwr[2]; // 0 = read, 1 = write
};

std::vector<Pipes> vec(N);

where N is the number of processes that you expect to fork.

Then after inserting items into the vector, you can use them as appropriate, within the dup2() call:


dup2(vec[0].rdwr[0], STDIN_FILENO);