1 /* 2 * Copyright (c) 1988 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * This code is derived from software written by Ken Arnold and 6 * published in UNIX Review, Vol. 6, No. 8. 7 * 8 * Redistribution and use in source and binary forms are permitted 9 * provided that the above copyright notice and this paragraph are 10 * duplicated in all such forms and that any documentation, 11 * advertising materials, and other materials related to such 12 * distribution and use acknowledge that the software was developed 13 * by the University of California, Berkeley. The name of the 14 * University may not be used to endorse or promote products derived 15 * from this software without specific prior written permission. 16 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 18 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 19 */ 20 21 #if defined(LIBC_SCCS) && !defined(lint) 22 static char sccsid[] = "@(#)popen.c 5.9 (Berkeley) 12/07/88"; 23 #endif /* LIBC_SCCS and not lint */ 24 25 #include <sys/param.h> 26 #include <sys/signal.h> 27 #include <sys/wait.h> 28 #include <stdio.h> 29 30 static pid_t *pids; 31 static int fds; 32 33 FILE * 34 popen(program, type) 35 char *program, *type; 36 { 37 FILE *iop; 38 int pdes[2], pid; 39 char *malloc(); 40 41 if (*type != 'r' && *type != 'w' || type[1]) 42 return(NULL); 43 44 if (pids == NULL) { 45 if ((fds = getdtablesize()) <= 0) 46 return(NULL); 47 if ((pids = (pid_t *)malloc((u_int)(fds * sizeof(int)))) == NULL) 48 return(NULL); 49 bzero((char *)pids, fds * sizeof(pid_t)); 50 } 51 if (pipe(pdes) < 0) 52 return(NULL); 53 switch (pid = vfork()) { 54 case -1: /* error */ 55 (void)close(pdes[0]); 56 (void)close(pdes[1]); 57 return(NULL); 58 /* NOTREACHED */ 59 case 0: /* child */ 60 if (*type == 'r') { 61 if (pdes[1] != 1) { 62 dup2(pdes[1], 1); 63 (void)close(pdes[1]); 64 } 65 (void)close(pdes[0]); 66 } else { 67 if (pdes[0] != 0) { 68 dup2(pdes[0], 0); 69 (void)close(pdes[0]); 70 } 71 (void)close(pdes[1]); 72 } 73 execl("/bin/sh", "sh", "-c", program, NULL); 74 _exit(127); 75 /* NOTREACHED */ 76 } 77 /* parent; assume fdopen can't fail... */ 78 if (*type == 'r') { 79 iop = fdopen(pdes[0], type); 80 (void)close(pdes[1]); 81 } else { 82 iop = fdopen(pdes[1], type); 83 (void)close(pdes[0]); 84 } 85 pids[fileno(iop)] = pid; 86 return(iop); 87 } 88 89 pclose(iop) 90 FILE *iop; 91 { 92 register int fdes; 93 int omask; 94 union wait pstat; 95 pid_t pid, waitpid(); 96 97 /* 98 * pclose returns -1 if stream is not associated with a 99 * `popened' command, if already `pclosed', or waitpid 100 * returns an error. 101 */ 102 if (pids == NULL || pids[fdes = fileno(iop)] == 0) 103 return(-1); 104 (void)fclose(iop); 105 omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP)); 106 pid = waitpid(pids[fdes], &pstat, 0); 107 (void)sigsetmask(omask); 108 pids[fdes] = 0; 109 return(pid == -1 ? -1 : pstat.w_status); 110 } 111