popen.c revision 40219
11573Srgrimes/* 21573Srgrimes * Copyright (c) 1988, 1993 31573Srgrimes * The Regents of the University of California. All rights reserved. 41573Srgrimes * 51573Srgrimes * This code is derived from software written by Ken Arnold and 61573Srgrimes * published in UNIX Review, Vol. 6, No. 8. 71573Srgrimes * 81573Srgrimes * Redistribution and use in source and binary forms, with or without 91573Srgrimes * modification, are permitted provided that the following conditions 101573Srgrimes * are met: 111573Srgrimes * 1. Redistributions of source code must retain the above copyright 121573Srgrimes * notice, this list of conditions and the following disclaimer. 131573Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 141573Srgrimes * notice, this list of conditions and the following disclaimer in the 151573Srgrimes * documentation and/or other materials provided with the distribution. 161573Srgrimes * 3. All advertising materials mentioning features or use of this software 171573Srgrimes * must display the following acknowledgement: 181573Srgrimes * This product includes software developed by the University of 191573Srgrimes * California, Berkeley and its contributors. 201573Srgrimes * 4. Neither the name of the University nor the names of its contributors 211573Srgrimes * may be used to endorse or promote products derived from this software 221573Srgrimes * without specific prior written permission. 231573Srgrimes * 241573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 251573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 261573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 271573Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 281573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 291573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 301573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 311573Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 321573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 331573Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 341573Srgrimes * SUCH DAMAGE. 351573Srgrimes */ 361573Srgrimes 371573Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 3823668Speterstatic char sccsid[] = "@(#)popen.c 8.3 (Berkeley) 5/3/95"; 391573Srgrimes#endif /* LIBC_SCCS and not lint */ 401573Srgrimes 411573Srgrimes#include <sys/param.h> 421573Srgrimes#include <sys/wait.h> 431573Srgrimes 441573Srgrimes#include <signal.h> 451573Srgrimes#include <errno.h> 461573Srgrimes#include <unistd.h> 471573Srgrimes#include <stdio.h> 481573Srgrimes#include <stdlib.h> 491573Srgrimes#include <string.h> 501573Srgrimes#include <paths.h> 511573Srgrimes 5240219Speterextern char **environ; 5340219Speter 541573Srgrimesstatic struct pid { 551573Srgrimes struct pid *next; 561573Srgrimes FILE *fp; 571573Srgrimes pid_t pid; 588870Srgrimes} *pidlist; 598870Srgrimes 601573SrgrimesFILE * 6123668Speterpopen(command, type) 6223668Speter const char *command, *type; 631573Srgrimes{ 641573Srgrimes struct pid *cur; 651573Srgrimes FILE *iop; 6623668Speter int pdes[2], pid, twoway; 6740219Speter char *argv[4]; 681573Srgrimes 6923668Speter /* 7023668Speter * Lite2 introduced two-way popen() pipes using socketpair(). 7123668Speter * FreeBSD's pipe() is bidirectional, so we use that. 7223668Speter */ 7323668Speter if (strchr(type, '+')) { 7423668Speter twoway = 1; 7523668Speter type = "r+"; 7623668Speter } else { 7723668Speter twoway = 0; 7823734Sbde if ((*type != 'r' && *type != 'w') || type[1]) 7923668Speter return (NULL); 8023668Speter } 8123668Speter if (pipe(pdes) < 0) 821573Srgrimes return (NULL); 831573Srgrimes 8423734Sbde if ((cur = malloc(sizeof(struct pid))) == NULL) { 8523734Sbde (void)close(pdes[0]); 8623734Sbde (void)close(pdes[1]); 871573Srgrimes return (NULL); 8823734Sbde } 891573Srgrimes 9040219Speter argv[0] = "sh"; 9140219Speter argv[1] = "-c"; 9240219Speter argv[2] = (char *)command; 9340219Speter argv[3] = NULL; 9440219Speter 9540219Speter switch (pid = vfork()) { 961573Srgrimes case -1: /* Error. */ 971573Srgrimes (void)close(pdes[0]); 981573Srgrimes (void)close(pdes[1]); 999272Shsu free(cur); 1001573Srgrimes return (NULL); 1011573Srgrimes /* NOTREACHED */ 1021573Srgrimes case 0: /* Child. */ 1031573Srgrimes if (*type == 'r') { 10424975Sdyson /* 10525063Sdyson * The dup2() to STDIN_FILENO is repeated to avoid 10625063Sdyson * writing to pdes[1], which might corrupt the 10725063Sdyson * parent's copy. This isn't good enough in 10825063Sdyson * general, since the _exit() is no return, so 10925063Sdyson * the compiler is free to corrupt all the local 11025063Sdyson * variables. 11124975Sdyson */ 1121573Srgrimes (void) close(pdes[0]); 11325063Sdyson if (pdes[1] != STDOUT_FILENO) { 11425063Sdyson (void)dup2(pdes[1], STDOUT_FILENO); 11525063Sdyson (void)close(pdes[1]); 11625084Sbde if (twoway) 11725084Sbde (void)dup2(STDOUT_FILENO, STDIN_FILENO); 11825063Sdyson } else if (twoway && (pdes[1] != STDIN_FILENO)) 11925063Sdyson (void)dup2(pdes[1], STDIN_FILENO); 1201573Srgrimes } else { 1211573Srgrimes if (pdes[0] != STDIN_FILENO) { 1221573Srgrimes (void)dup2(pdes[0], STDIN_FILENO); 1231573Srgrimes (void)close(pdes[0]); 1241573Srgrimes } 1251573Srgrimes (void)close(pdes[1]); 1261573Srgrimes } 12740219Speter execve(_PATH_BSHELL, argv, environ); 1281573Srgrimes _exit(127); 1291573Srgrimes /* NOTREACHED */ 1301573Srgrimes } 1311573Srgrimes 1321573Srgrimes /* Parent; assume fdopen can't fail. */ 1331573Srgrimes if (*type == 'r') { 1341573Srgrimes iop = fdopen(pdes[0], type); 1351573Srgrimes (void)close(pdes[1]); 1361573Srgrimes } else { 1371573Srgrimes iop = fdopen(pdes[1], type); 1381573Srgrimes (void)close(pdes[0]); 1391573Srgrimes } 1401573Srgrimes 1411573Srgrimes /* Link into list of file descriptors. */ 1421573Srgrimes cur->fp = iop; 1431573Srgrimes cur->pid = pid; 1441573Srgrimes cur->next = pidlist; 1451573Srgrimes pidlist = cur; 1461573Srgrimes 1471573Srgrimes return (iop); 1481573Srgrimes} 1491573Srgrimes 1501573Srgrimes/* 1511573Srgrimes * pclose -- 1521573Srgrimes * Pclose returns -1 if stream is not associated with a `popened' command, 1531573Srgrimes * if already `pclosed', or waitpid returns an error. 1541573Srgrimes */ 1551573Srgrimesint 1561573Srgrimespclose(iop) 1571573Srgrimes FILE *iop; 1581573Srgrimes{ 1591573Srgrimes register struct pid *cur, *last; 1601573Srgrimes int omask; 16123668Speter int pstat; 1621573Srgrimes pid_t pid; 1631573Srgrimes 1641573Srgrimes /* Find the appropriate file pointer. */ 1651573Srgrimes for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) 1661573Srgrimes if (cur->fp == iop) 1671573Srgrimes break; 1681573Srgrimes if (cur == NULL) 1691573Srgrimes return (-1); 1701573Srgrimes 17123668Speter (void)fclose(iop); 17223668Speter 1731573Srgrimes do { 17423668Speter pid = waitpid(cur->pid, &pstat, 0); 1751573Srgrimes } while (pid == -1 && errno == EINTR); 1761573Srgrimes 1771573Srgrimes /* Remove the entry from the linked list. */ 1781573Srgrimes if (last == NULL) 1791573Srgrimes pidlist = cur->next; 1801573Srgrimes else 1811573Srgrimes last->next = cur->next; 1821573Srgrimes free(cur); 1838870Srgrimes 18423668Speter return (pid == -1 ? -1 : pstat); 1851573Srgrimes} 186