1 /* 2 * Copyright (c) 1988, 1993 3 * The Regents of the University of California. 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, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char sccsid[] = "@(#)popen.c 8.3 (Berkeley) 5/3/95"; 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <sys/param.h> 42 #include <sys/wait.h> 43 44 #include <signal.h> 45 #include <errno.h> 46 #include <unistd.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <string.h> 50 #include <paths.h> 51 52 extern char **environ; 53 54 static struct pid { 55 struct pid *next; 56 FILE *fp; 57 pid_t pid; 58 } *pidlist; 59 60 FILE * 61 popen(command, type) 62 const char *command, *type; 63 { 64 struct pid *cur; 65 FILE *iop; 66 int pdes[2], pid, twoway; 67 char *argv[4]; 68 struct pid *p; 69 70 /* 71 * Lite2 introduced two-way popen() pipes using socketpair(). 72 * FreeBSD's pipe() is bidirectional, so we use that. 73 */ 74 if (strchr(type, '+')) { 75 twoway = 1; 76 type = "r+"; 77 } else { 78 twoway = 0; 79 if ((*type != 'r' && *type != 'w') || type[1]) 80 return (NULL); 81 } 82 if (pipe(pdes) < 0) 83 return (NULL); 84 85 if ((cur = malloc(sizeof(struct pid))) == NULL) { 86 (void)close(pdes[0]); 87 (void)close(pdes[1]); 88 return (NULL); 89 } 90 91 argv[0] = "sh"; 92 argv[1] = "-c"; 93 argv[2] = (char *)command; 94 argv[3] = NULL; 95 96 switch (pid = vfork()) { 97 case -1: /* Error. */ 98 (void)close(pdes[0]); 99 (void)close(pdes[1]); 100 free(cur); 101 return (NULL); 102 /* NOTREACHED */ 103 case 0: /* Child. */ 104 if (*type == 'r') { 105 /* 106 * The dup2() to STDIN_FILENO is repeated to avoid 107 * writing to pdes[1], which might corrupt the 108 * parent's copy. This isn't good enough in 109 * general, since the _exit() is no return, so 110 * the compiler is free to corrupt all the local 111 * variables. 112 */ 113 (void) close(pdes[0]); 114 if (pdes[1] != STDOUT_FILENO) { 115 (void)dup2(pdes[1], STDOUT_FILENO); 116 (void)close(pdes[1]); 117 if (twoway) 118 (void)dup2(STDOUT_FILENO, STDIN_FILENO); 119 } else if (twoway && (pdes[1] != STDIN_FILENO)) 120 (void)dup2(pdes[1], STDIN_FILENO); 121 } else { 122 if (pdes[0] != STDIN_FILENO) { 123 (void)dup2(pdes[0], STDIN_FILENO); 124 (void)close(pdes[0]); 125 } 126 (void)close(pdes[1]); 127 } 128 for (p = pidlist; p; p = p->next) { 129 (void)close(fileno(p->fp)); 130 } 131 execve(_PATH_BSHELL, argv, environ); 132 _exit(127); 133 /* NOTREACHED */ 134 } 135 136 /* Parent; assume fdopen can't fail. */ 137 if (*type == 'r') { 138 iop = fdopen(pdes[0], type); 139 (void)close(pdes[1]); 140 } else { 141 iop = fdopen(pdes[1], type); 142 (void)close(pdes[0]); 143 } 144 145 /* Link into list of file descriptors. */ 146 cur->fp = iop; 147 cur->pid = pid; 148 cur->next = pidlist; 149 pidlist = cur; 150 151 return (iop); 152 } 153 154 /* 155 * pclose -- 156 * Pclose returns -1 if stream is not associated with a `popened' command, 157 * if already `pclosed', or waitpid returns an error. 158 */ 159 int 160 pclose(iop) 161 FILE *iop; 162 { 163 register struct pid *cur, *last; 164 int omask; 165 int pstat; 166 pid_t pid; 167 168 /* Find the appropriate file pointer. */ 169 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) 170 if (cur->fp == iop) 171 break; 172 if (cur == NULL) 173 return (-1); 174 175 (void)fclose(iop); 176 177 do { 178 pid = waitpid(cur->pid, &pstat, 0); 179 } while (pid == -1 && errno == EINTR); 180 181 /* Remove the entry from the linked list. */ 182 if (last == NULL) 183 pidlist = cur->next; 184 else 185 last->next = cur->next; 186 free(cur); 187 188 return (pid == -1 ? -1 : pstat); 189 } 190