1 /* 2 * Copyright (c) 1980 Regents of the University of California. 3 * All rights reserved. The Berkeley software License Agreement 4 * specifies the terms and conditions for redistribution. 5 */ 6 7 #if defined(LIBC_SCCS) && !defined(lint) 8 static char sccsid[] = "@(#)popen.c 5.4 (Berkeley) 03/26/86"; 9 #endif LIBC_SCCS and not lint 10 11 #include <stdio.h> 12 #include <signal.h> 13 14 #define tst(a,b) (*mode == 'r'? (b) : (a)) 15 #define RDR 0 16 #define WTR 1 17 18 extern char *malloc(); 19 20 static int *popen_pid; 21 static int nfiles; 22 23 FILE * 24 popen(cmd,mode) 25 char *cmd; 26 char *mode; 27 { 28 int p[2]; 29 int myside, hisside, pid; 30 31 if (nfiles <= 0) 32 nfiles = getdtablesize(); 33 if (popen_pid == NULL) { 34 popen_pid = (int *)malloc(nfiles * sizeof *popen_pid); 35 if (popen_pid == NULL) 36 return (NULL); 37 for (pid = 0; pid < nfiles; pid++) 38 popen_pid[pid] = -1; 39 } 40 if (pipe(p) < 0) 41 return (NULL); 42 myside = tst(p[WTR], p[RDR]); 43 hisside = tst(p[RDR], p[WTR]); 44 if ((pid = vfork()) == 0) { 45 /* myside and hisside reverse roles in child */ 46 close(myside); 47 if (hisside != tst(0, 1)) { 48 dup2(hisside, tst(0, 1)); 49 close(hisside); 50 } 51 execl("/bin/sh", "sh", "-c", cmd, (char *)NULL); 52 _exit(127); 53 } 54 if (pid == -1) { 55 close(myside); 56 close(hisside); 57 return (NULL); 58 } 59 popen_pid[myside] = pid; 60 close(hisside); 61 return (fdopen(myside, mode)); 62 } 63 64 pclose(ptr) 65 FILE *ptr; 66 { 67 int child, pid, status, omask; 68 69 child = popen_pid[fileno(ptr)]; 70 popen_pid[fileno(ptr)] = -1; 71 fclose(ptr); 72 if (child == -1) 73 return (-1); 74 omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP)); 75 while ((pid = wait(&status)) != child && pid != -1) 76 ; 77 (void) sigsetmask(omask); 78 return (pid == -1 ? -1 : status); 79 } 80