#include <stdio.h> #include <signal.h> #define tst(a,b) (*mode == 'r'? (b) : (a)) #define RDR 0 #define WTR 1 static int popen_pid[20]; FILE * popen(cmd,mode) char *cmd; char *mode; { int p[2]; register myside, hisside, pid; if(pipe(p) < 0) return NULL; myside = tst(p[WTR], p[RDR]); hisside = tst(p[RDR], p[WTR]); if((pid = fork()) == 0) { /* myside and hisside reverse roles in child */ close(myside); dup2(hisside, tst(0, 1)); close(hisside); execl("/bin/sh", "sh", "-c", cmd, 0); _exit(1); } if(pid == -1) return NULL; popen_pid[myside] = pid; close(hisside); return(fdopen(myside, mode)); } pclose(ptr) FILE *ptr; { register f, r, (*hstat)(), (*istat)(), (*qstat)(); int status; f = fileno(ptr); fclose(ptr); istat = signal(SIGINT, SIG_IGN); qstat = signal(SIGQUIT, SIG_IGN); hstat = signal(SIGHUP, SIG_IGN); while((r = wait(&status)) != popen_pid[f] && r != -1) ; if(r == -1) status = -1; signal(SIGINT, istat); signal(SIGQUIT, qstat); signal(SIGHUP, hstat); return(status); }