#ifndef lint static char *sccsid = "@(#)popen.c 1.7 (Berkeley) 8/13/83"; #endif #include <stdio.h> #include <signal.h> #include <errno.h> #define tst(a,b) (*mode == 'r'? (b) : (a)) #define RDR 0 #define WTR 1 static int popen_pid[20]; #ifdef VMUNIX #define mask(s) (1<<((s)-1)) #else #define vfork fork #endif VMUNIX #ifndef SIGRETRO #define sigchild() #endif 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 = vfork()) == 0) { /* myside and hisside reverse roles in child */ sigchild(); close(myside); dup2(hisside, tst(0, 1)); close(hisside); execl("/bin/sh", "sh", "-c", cmd, 0); /* mjm: csh --> sh */ perror("/bin/sh"); /* mjm */ _exit(1); } if(pid == -1) return NULL; popen_pid[myside] = pid; close(hisside); return(fdopen(myside, mode)); } pclose(ptr) FILE *ptr; { register f, r; int status, omask; extern int errno; f = fileno(ptr); fclose(ptr); while((r = wait(&status)) != popen_pid[f] && r != -1 && errno != EINTR) ; if(r == -1) status = -1; return(status); }