popen.c revision 1.34
1 /* $NetBSD: popen.c,v 1.34 2015/01/20 18:31:25 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software written by Ken Arnold and 8 * published in UNIX Review, Vol. 6, No. 8. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)popen.c 8.3 (Berkeley) 5/3/95"; 39 #else 40 __RCSID("$NetBSD: popen.c,v 1.34 2015/01/20 18:31:25 christos Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include "namespace.h" 45 #include <sys/param.h> 46 #include <sys/wait.h> 47 #include <sys/socket.h> 48 49 #include <assert.h> 50 #include <errno.h> 51 #include <paths.h> 52 #include <signal.h> 53 #include <stdio.h> 54 #include <stdlib.h> 55 #include <string.h> 56 #include <unistd.h> 57 #include <fcntl.h> 58 59 #include "env.h" 60 61 #ifdef __weak_alias 62 __weak_alias(popen,_popen) 63 __weak_alias(pclose,_pclose) 64 #endif 65 66 static struct pid { 67 struct pid *next; 68 FILE *fp; 69 #ifdef _REENTRANT 70 int fd; 71 #endif 72 pid_t pid; 73 } *pidlist; 74 75 #ifdef _REENTRANT 76 static rwlock_t pidlist_lock = RWLOCK_INITIALIZER; 77 #endif 78 79 static struct pid * 80 pdes_get(int *pdes, const char **type) 81 { 82 struct pid *cur; 83 int flags = strchr(*type, 'e') ? O_CLOEXEC : 0; 84 int serrno; 85 86 if (strchr(*type, '+')) { 87 int stype = flags ? (SOCK_STREAM | SOCK_CLOEXEC) : SOCK_STREAM; 88 *type = "r+"; 89 if (socketpair(AF_LOCAL, stype, 0, pdes) < 0) 90 return NULL; 91 } else { 92 *type = strrchr(*type, 'r') ? "r" : "w"; 93 if (pipe2(pdes, flags) == -1) 94 return NULL; 95 } 96 97 if ((cur = malloc(sizeof(*cur))) != NULL) 98 return cur; 99 serrno = errno; 100 (void)close(pdes[0]); 101 (void)close(pdes[1]); 102 errno = serrno; 103 return NULL; 104 } 105 106 static void 107 pdes_child(int *pdes, const char *type) 108 { 109 struct pid *old; 110 111 /* POSIX.2 B.3.2.2 "popen() shall ensure that any streams 112 from previous popen() calls that remain open in the 113 parent process are closed in the new child process. */ 114 for (old = pidlist; old; old = old->next) 115 #ifdef _REENTRANT 116 (void)close(old->fd); /* don't allow a flush */ 117 #else 118 (void)close(fileno(old->fp)); /* don't allow a flush */ 119 #endif 120 121 if (type[0] == 'r') { 122 (void)close(pdes[0]); 123 if (pdes[1] != STDOUT_FILENO) { 124 (void)dup2(pdes[1], STDOUT_FILENO); 125 (void)close(pdes[1]); 126 } 127 if (type[1] == '+') 128 (void)dup2(STDOUT_FILENO, STDIN_FILENO); 129 } else { 130 (void)close(pdes[1]); 131 if (pdes[0] != STDIN_FILENO) { 132 (void)dup2(pdes[0], STDIN_FILENO); 133 (void)close(pdes[0]); 134 } 135 } 136 } 137 138 static void 139 pdes_parent(int *pdes, struct pid *cur, pid_t pid, const char *type) 140 { 141 FILE *iop; 142 143 /* Parent; assume fdopen can't fail. */ 144 if (*type == 'r') { 145 iop = fdopen(pdes[0], type); 146 #ifdef _REENTRANT 147 cur->fd = pdes[0]; 148 #endif 149 (void)close(pdes[1]); 150 } else { 151 iop = fdopen(pdes[1], type); 152 #ifdef _REENTRANT 153 cur->fd = pdes[1]; 154 #endif 155 (void)close(pdes[0]); 156 } 157 158 /* Link into list of file descriptors. */ 159 cur->fp = iop; 160 cur->pid = pid; 161 cur->next = pidlist; 162 pidlist = cur; 163 } 164 165 static void 166 pdes_error(int *pdes, struct pid *cur) 167 { 168 free(cur); 169 (void)close(pdes[0]); 170 (void)close(pdes[1]); 171 } 172 173 FILE * 174 popen(const char *cmd, const char *type) 175 { 176 struct pid *cur; 177 int pdes[2], serrno; 178 pid_t pid; 179 180 _DIAGASSERT(cmd != NULL); 181 _DIAGASSERT(type != NULL); 182 183 if ((cur = pdes_get(pdes, &type)) == NULL) 184 return NULL; 185 186 #ifdef _REENTRANT 187 (void)rwlock_rdlock(&pidlist_lock); 188 #endif 189 (void)__readlockenv(); 190 switch (pid = vfork()) { 191 case -1: /* Error. */ 192 serrno = errno; 193 (void)__unlockenv(); 194 #ifdef _REENTRANT 195 (void)rwlock_unlock(&pidlist_lock); 196 #endif 197 errno = serrno; 198 return NULL; 199 /* NOTREACHED */ 200 case 0: /* Child. */ 201 pdes_child(pdes, type); 202 execl(_PATH_BSHELL, "sh", "-c", cmd, NULL); 203 _exit(127); 204 /* NOTREACHED */ 205 } 206 (void)__unlockenv(); 207 208 pdes_parent(pdes, cur, pid, type); 209 210 #ifdef _REENTRANT 211 (void)rwlock_unlock(&pidlist_lock); 212 #endif 213 214 return cur->fp; 215 } 216 217 FILE * 218 popenve(const char *cmd, char *const *argv, char *const *envp, const char *type) 219 { 220 struct pid *cur; 221 int pdes[2], serrno; 222 pid_t pid; 223 224 _DIAGASSERT(cmd != NULL); 225 _DIAGASSERT(type != NULL); 226 227 if ((cur = pdes_get(pdes, &type)) == NULL) 228 return NULL; 229 230 #ifdef _REENTRANT 231 (void)rwlock_rdlock(&pidlist_lock); 232 #endif 233 switch (pid = vfork()) { 234 case -1: /* Error. */ 235 serrno = errno; 236 #ifdef _REENTRANT 237 (void)rwlock_unlock(&pidlist_lock); 238 #endif 239 pdes_error(pdes, cur); 240 errno = serrno; 241 return NULL; 242 /* NOTREACHED */ 243 case 0: /* Child. */ 244 pdes_child(pdes, type); 245 execve(cmd, argv, envp); 246 _exit(127); 247 /* NOTREACHED */ 248 } 249 250 pdes_parent(pdes, cur, pid, type); 251 252 #ifdef _REENTRANT 253 (void)rwlock_unlock(&pidlist_lock); 254 #endif 255 256 return cur->fp; 257 } 258 259 /* 260 * pclose -- 261 * Pclose returns -1 if stream is not associated with a `popened' command, 262 * if already `pclosed', or waitpid returns an error. 263 */ 264 int 265 pclose(FILE *iop) 266 { 267 struct pid *cur, *last; 268 int pstat; 269 pid_t pid; 270 271 _DIAGASSERT(iop != NULL); 272 273 #ifdef _REENTRANT 274 rwlock_wrlock(&pidlist_lock); 275 #endif 276 277 /* Find the appropriate file pointer. */ 278 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) 279 if (cur->fp == iop) 280 break; 281 if (cur == NULL) { 282 #ifdef _REENTRANT 283 (void)rwlock_unlock(&pidlist_lock); 284 #endif 285 errno = ESRCH; 286 return -1; 287 } 288 289 (void)fclose(iop); 290 291 /* Remove the entry from the linked list. */ 292 if (last == NULL) 293 pidlist = cur->next; 294 else 295 last->next = cur->next; 296 297 #ifdef _REENTRANT 298 (void)rwlock_unlock(&pidlist_lock); 299 #endif 300 301 do { 302 pid = waitpid(cur->pid, &pstat, 0); 303 } while (pid == -1 && errno == EINTR); 304 305 free(cur); 306 307 return pid == -1 ? -1 : pstat; 308 } 309
Indexes created Fri Sep 26 20:09:58 GMT 2025