Subversion Repositories planix.SVN

#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/wait.h>

#define MAXFORKS        20
#define NSYSFILE        3
#define tst(a,b)        (*mode == 'r'? (b) : (a))
#define RDR     0
#define WTR     1

struct a_fork {
        short   done;
        short   fd;
        int     pid;
        int     status;
};
static struct a_fork the_fork[MAXFORKS];

FILE *
popen(char *cmd, char *mode)
{
        int p[2];
        int myside, hisside, pid;
        int i, ind;

        for (ind = 0; ind < MAXFORKS; ind++)
                if (the_fork[ind].pid == 0)
                        break;
        if (ind == MAXFORKS)
                return NULL;
        if(pipe(p) < 0)
                return NULL;
        myside = tst(p[WTR], p[RDR]);
        hisside = tst(p[RDR], p[WTR]);
        switch (pid = fork()) {
        case -1:
                return NULL;
        case 0:
                /* myside and hisside reverse roles in child */
                close(myside);
                dup2(hisside, tst(0, 1));
                for (i=NSYSFILE; i<FOPEN_MAX; i++)
                        close(i);
                execl("/bin/ape/sh", "sh", "-c", cmd, NULL);
                _exit(1);
        default:
                the_fork[ind].pid = pid;
                the_fork[ind].fd = myside;
                the_fork[ind].done = 0;
                close(hisside);
                return(fdopen(myside, mode));
        }
}

int
pclose(FILE *ptr)
{
        int f, r, ind;
        int status;

        f = fileno(ptr);
        fclose(ptr);
        for (ind = 0; ind < MAXFORKS; ind++)
                if (the_fork[ind].fd == f && the_fork[ind].pid != 0)
                        break;
        if (ind == MAXFORKS)
                return 0;
        if (!the_fork[ind].done) {
                do {
                        r = wait(&status);
                        for (f = 0; f < MAXFORKS; f++)
                                if (the_fork[f].pid == r) {
                                        the_fork[f].done = 1;
                                        the_fork[f].status = status;
                                        break;
                                }
                } while(r != the_fork[ind].pid && r != -1);
                the_fork[ind].status = r == -1 ? -1 : status;
        }
        the_fork[ind].pid = 0;
        return (the_fork[ind].status);
}