Open Source Projects Europe

#ifndef lint
static char rcsid[] = "@(#$Id: execmd.cpp,v 1.2 2004-12-14 17:54:16 dockes Exp $ (C) 2004 J.F.Dockes";
#endif

#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/select.h>
#include <fcntl.h>

#include <list>
#include <string>
#include <sstream>
#include <iostream>

#include "execmd.h"
#include "pathut.h"

using namespace std;
#define MAX(A,B) (A>B?A:B)

int
ExecCmd::doexec(const string &cmd, const list<string> args,
		const string *input, string *output)
{

    int pipein[2]; // subproc input
    int pipeout[2]; // subproc output
    pipein[0] = pipein[1] = pipeout[0] = pipeout[1] = -1;

    if (input && pipe(pipein) < 0) {
	return -1;
    }
    if (output && pipe(pipeout) < 0) {
	close(pipein[0]);
	close(pipein[1]);
	return -1;
    }

    pid_t pid = fork();
    if (pid < 0) {
	return -1;
    }

    if (pid) {
	if (input) {
	    close(pipein[0]);
	    pipein[0] = -1;
	}
	if (output) {
	    close(pipeout[1]);
	    pipeout[1] = -1;
	}
	fd_set readfds, writefds;
	if (input || output) {
	    if (input)
		fcntl(pipein[1], F_SETFL, O_NONBLOCK);
	    if (output)	
		fcntl(pipeout[0], F_SETFL, O_NONBLOCK);
	    int nwritten = 0;
	    int nfds = MAX(pipein[1], pipeout[0]) + 1;
	    for(;nfds > 0;) {
		FD_ZERO(&writefds);
		FD_ZERO(&readfds);
		if (pipein[1] >= 0)
		    FD_SET(pipein[1], &writefds);
		if (pipeout[0] >= 0)
		    FD_SET(pipeout[0], &readfds);
		nfds = MAX(pipein[1], pipeout[0]) + 1;
		//struct timeval to; to.tv_sec = 1;to.tv_usec=0;
		//cerr << "pipein[1] "<< pipein[1] << " pipeout[0] " << 
		//pipeout[0] << " nfds " << nfds << endl;
		if (select(nfds, &readfds, &writefds, 0, 0) <= 0) {
		    perror("select");
		    break;
		}
		if (pipein[1] >= 0 && FD_ISSET(pipein[1], &writefds)) {
		    int n = write(pipein[1], input->c_str()+nwritten, 
				  input->length() - nwritten);
		    if (n < 0) {
			goto out;
		    }
		    nwritten += n;
		    if (nwritten == input->length()) {
			// cerr << "Closing output" << endl;
			close(pipein[1]);
			pipein[1] = -1;
		    }
		}
		if (pipeout[0] > 0 && FD_ISSET(pipeout[0], &readfds)) {
		    char buf[1024];
		    int n = read(pipeout[0], buf, 1024);
		    if (n == 0) {
			goto out;
		    } else if (n < 0) {
			perror("read");
			goto out;
		    } else if (n > 0) {
			// cerr << "READ: " << n << endl;
			output->append(buf, n);
		    }
		}
	    }

	}
    out:
	int status;
	pid = waitpid(pid, &status, 0);
	if (pipein[0] >= 0)
	    close(pipein[0]);
	if (pipein[1] >= 0)
	    close(pipein[1]);
	if (pipeout[0] >= 0)
	    close(pipeout[0]);
	if (pipeout[1] >= 0)
	    close(pipeout[1]);
	return status;
    } else {
	if (input) {
	    close(pipein[1]);
	    pipein[1] = -1;
	    if (pipein[0] != 0) {
		dup2(pipein[0], 0);
		close(pipein[0]);
		pipein[0] = -1;
	    }
	}
	if (output) {
	    close(pipeout[0]);
	    pipeout[0] = -1;
	    if (pipeout[1] != 1) {
		if (dup2(pipeout[1], 1) < 0) {
		    perror("dup2");
		}
		if (close(pipeout[1]) < 0) {
		    perror("close");
		}
		pipeout[1] = -1;
	    }
	}

	// Count args
	list<string>::const_iterator it;
	int i = 0;
	for (it = args.begin(); it != args.end(); it++) i++;
	// Allocate arg vector (2 more for arg0 + final 0)
	typedef const char *Ccharp;
	Ccharp *argv;
	argv = (Ccharp *)malloc((i+2) * sizeof(char *));
	if (argv == 0) {
	    cerr << "Malloc error" << endl;
	    exit(1);
	}
	
	// Fill up argv
	argv[0] = path_getsimple(cmd).c_str();
	i = 1;
	for (it = args.begin(); it != args.end(); it++) {
	    argv[i++] = it->c_str();
	}
	argv[i] = 0;

#if 0
	{int i = 0;cerr << "cmd: " << cmd << endl << "ARGS: " << endl; 
	    while (argv[i]) cerr << argv[i++] << endl;}
#endif

	execvp(cmd.c_str(), (char *const*)argv);
	// Hu ho
	//cerr << "Exec failed" << endl;
	exit(1);
    }
}

const char *data = "Une ligne de donnees\n";

int main(int argc, const char **argv)
{
    if (argc < 2) {
	cerr << "Usage: execmd cmd arg1 arg2 ..." << endl;
	exit(1);
    }
    const string cmd = argv[1];
    list<string> l;
    for (int i = 2; i < argc; i++) {
	l.push_back(argv[i]);
    }
    ExecCmd mexec;
    string input, output;
    input = data;
    string *ip = 0;
    //ip = &input;
    int status = mexec.doexec(cmd, l, ip, &output);
    cout << "Status: " << status << endl;
    cout << "Output:" << output << endl;
    exit (status >> 8);
}