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 5.11 (Berkeley) 11/28/89"; 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 #include <unistd.h> 30 #include <paths.h> 31 32 static pid_t *pids; 33 static int fds; 34 35 FILE * 36 popen(program, type) 37 char *program, *type; 38 { 39 FILE *iop; 40 int pdes[2], pid; 41 char *malloc(); 42 43 if (*type != 'r' && *type != 'w' || type[1]) 44 return(NULL); 45 46 if (pids == NULL) { 47 if ((fds = getdtablesize()) <= 0) 48 return(NULL); 49 if ((pids = (pid_t *)malloc((u_int)(fds * sizeof(int)))) == NULL) 50 return(NULL); 51 bzero((char *)pids, fds * sizeof(pid_t)); 52 } 53 if (pipe(pdes) < 0) 54 return(NULL); 55 switch (pid = vfork()) { 56 case -1: /* error */ 57 (void)close(pdes[0]); 58 (void)close(pdes[1]); 59 return(NULL); 60 /* NOTREACHED */ 61 case 0: /* child */ 62 if (*type == 'r') { 63 if (pdes[1] != STDOUT_FILENO) { 64 (void)dup2(pdes[1], STDOUT_FILENO); 65 (void)close(pdes[1]); 66 } 67 (void)close(pdes[0]); 68 } else { 69 if (pdes[0] != STDIN_FILENO) { 70 (void)dup2(pdes[0], STDIN_FILENO); 71 (void)close(pdes[0]); 72 } 73 (void)close(pdes[1]); 74 } 75 execl(_PATH_BSHELL, "sh", "-c", program, NULL); 76 _exit(127); 77 /* NOTREACHED */ 78 } 79 /* parent; assume fdopen can't fail... */ 80 if (*type == 'r') { 81 iop = fdopen(pdes[0], type); 82 (void)close(pdes[1]); 83 } else { 84 iop = fdopen(pdes[1], type); 85 (void)close(pdes[0]); 86 } 87 pids[fileno(iop)] = pid; 88 return(iop); 89 } 90 91 pclose(iop) 92 FILE *iop; 93 { 94 register int fdes; 95 int omask; 96 union wait pstat; 97 pid_t pid, waitpid(); 98 99 /* 100 * pclose returns -1 if stream is not associated with a 101 * `popened' command, if already `pclosed', or waitpid 102 * returns an error. 103 */ 104 if (pids == NULL || pids[fdes = fileno(iop)] == 0) 105 return(-1); 106 (void)fclose(iop); 107 omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP)); 108 pid = waitpid(pids[fdes], &pstat, 0); 109 (void)sigsetmask(omask); 110 pids[fdes] = 0; 111 return(pid == -1 ? -1 : pstat.w_status); 112 } 113