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 5.7 (Berkeley) 09/01/88"; 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 uid_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) { 45 if ((fds = getdtablesize()) <= 0) 46 return(NULL); 47 if (!(pids = 48 (uid_t *)malloc((u_int)(fds * sizeof(uid_t))))) 49 return(NULL); 50 bzero(pids, fds * sizeof(uid_t)); 51 } 52 if (pipe(pdes) < 0) 53 return(NULL); 54 switch(pid = vfork()) { 55 case -1: /* error */ 56 (void)close(pdes[0]); 57 (void)close(pdes[1]); 58 return(NULL); 59 /* NOTREACHED */ 60 case 0: /* child */ 61 if (*type == 'r') { 62 if (pdes[1] != 1) { 63 dup2(pdes[1], 1); 64 (void)close(pdes[1]); 65 } 66 (void)close(pdes[0]); 67 } else { 68 if (pdes[0] != 0) { 69 dup2(pdes[0], 0); 70 (void)close(pdes[0]); 71 } 72 (void)close(pdes[1]); 73 } 74 execl("/bin/sh", "sh", "-c", program, NULL); 75 _exit(127); 76 /* NOTREACHED */ 77 } 78 /* parent; assume fdopen can't fail... */ 79 if (*type == 'r') { 80 iop = fdopen(pdes[0], type); 81 (void)close(pdes[1]); 82 } else { 83 iop = fdopen(pdes[1], type); 84 (void)close(pdes[0]); 85 } 86 pids[fileno(iop)] = pid; 87 return(iop); 88 } 89 90 pclose(iop) 91 FILE *iop; 92 { 93 register int fdes; 94 long omask; 95 int stat_loc; 96 pid_t waitpid(); 97 98 /* 99 * pclose returns -1 if stream is not associated with a 100 * `popened' command, or, if already `pclosed'. 101 */ 102 if (pids[fdes = fileno(iop)] == 0) 103 return(-1); 104 (void)fclose(iop); 105 omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP)); 106 stat_loc = waitpid(pids[fdes], &stat_loc, 0) == -1 ? 107 -1 : WEXITSTATUS(stat_loc); 108 (void)sigsetmask(omask); 109 pids[fdes] = 0; 110 return(stat_loc); 111 } 112