/********************************************************************** * Copyright (c) Digital Equipment Corporation 1984, 1985, 1986. * * All Rights Reserved. * * Reference "/usr/src/COPYRIGHT" for applicable restrictions. * **********************************************************************/ #ifndef lint static char *Sccsid = "@(#)popen.c 3.0 4/22/86"; #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]; /* * Based on * static char *sccsid = "@(#)popen.c 1.6 6/12/83"; */ # ifndef VMUNIX # 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/csh", "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; int status; extern int errno; f = fileno(ptr); fclose(ptr); # ifdef VMUNIX sighold(SIGINT); sighold(SIGQUIT); sighold(SIGHUP); # endif VMUNIX while((r = wait(&status)) != popen_pid[f] && r != -1 && errno != EINTR) ; if(r == -1) status = -1; # ifdef VMUNIX sigrelse(SIGINT); sigrelse(SIGQUIT); sigrelse(SIGHUP); # endif VMUNIX return(status); }