1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Kenneth Almquist. 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 #ifndef lint 36 #if 0 37 static char sccsid[] = "@(#)redir.c 8.2 (Berkeley) 5/4/95"; 38 #endif 39 #endif /* not lint */ 40 #include <sys/cdefs.h> 41 __FBSDID("$FreeBSD$"); 42 43 #include <sys/types.h> 44 #include <sys/stat.h> 45 #include <signal.h> 46 #include <string.h> 47 #include <fcntl.h> 48 #include <errno.h> 49 #include <unistd.h> 50 #include <stdlib.h> 51 52 /* 53 * Code for dealing with input/output redirection. 54 */ 55 56 #include "shell.h" 57 #include "nodes.h" 58 #include "jobs.h" 59 #include "expand.h" 60 #include "redir.h" 61 #include "output.h" 62 #include "memalloc.h" 63 #include "error.h" 64 #include "options.h" 65 66 67 #define EMPTY -2 /* marks an unused slot in redirtab */ 68 #define CLOSED -1 /* fd was not open before redir */ 69 70 71 struct redirtab { 72 struct redirtab *next; 73 int renamed[10]; 74 int fd0_redirected; 75 unsigned int empty_redirs; 76 }; 77 78 79 static struct redirtab *redirlist; 80 81 /* 82 * We keep track of whether or not fd0 has been redirected. This is for 83 * background commands, where we want to redirect fd0 to /dev/null only 84 * if it hasn't already been redirected. 85 */ 86 static int fd0_redirected = 0; 87 88 /* Number of redirtabs that have not been allocated. */ 89 static unsigned int empty_redirs = 0; 90 91 static void openredirect(union node *, char[10 ]); 92 static int openhere(union node *); 93 94 95 /* 96 * Process a list of redirection commands. If the REDIR_PUSH flag is set, 97 * old file descriptors are stashed away so that the redirection can be 98 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the 99 * standard output, and the standard error if it becomes a duplicate of 100 * stdout, is saved in memory. 101 * 102 * We suppress interrupts so that we won't leave open file 103 * descriptors around. Because the signal handler remains 104 * installed and we do not use system call restart, interrupts 105 * will still abort blocking opens such as fifos (they will fail 106 * with EINTR). There is, however, a race condition if an interrupt 107 * arrives after INTOFF and before open blocks. 108 */ 109 110 void 111 redirect(union node *redir, int flags) 112 { 113 union node *n; 114 struct redirtab *sv = NULL; 115 int i; 116 int fd; 117 char memory[10]; /* file descriptors to write to memory */ 118 119 INTOFF; 120 for (i = 10 ; --i >= 0 ; ) 121 memory[i] = 0; 122 memory[1] = flags & REDIR_BACKQ; 123 if (flags & REDIR_PUSH) { 124 empty_redirs++; 125 if (redir != NULL) { 126 sv = ckmalloc(sizeof (struct redirtab)); 127 for (i = 0 ; i < 10 ; i++) 128 sv->renamed[i] = EMPTY; 129 sv->fd0_redirected = fd0_redirected; 130 sv->empty_redirs = empty_redirs - 1; 131 sv->next = redirlist; 132 redirlist = sv; 133 empty_redirs = 0; 134 } 135 } 136 for (n = redir ; n ; n = n->nfile.next) { 137 fd = n->nfile.fd; 138 if (fd == 0) 139 fd0_redirected = 1; 140 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) && 141 n->ndup.dupfd == fd) 142 continue; /* redirect from/to same file descriptor */ 143 144 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { 145 INTOFF; 146 if ((i = fcntl(fd, F_DUPFD_CLOEXEC, 10)) == -1) { 147 switch (errno) { 148 case EBADF: 149 i = CLOSED; 150 break; 151 default: 152 INTON; 153 error("%d: %s", fd, strerror(errno)); 154 break; 155 } 156 } 157 sv->renamed[fd] = i; 158 INTON; 159 } 160 openredirect(n, memory); 161 INTON; 162 INTOFF; 163 } 164 if (memory[1]) 165 out1 = &memout; 166 if (memory[2]) 167 out2 = &memout; 168 INTON; 169 } 170 171 172 static void 173 openredirect(union node *redir, char memory[10]) 174 { 175 struct stat sb; 176 int fd = redir->nfile.fd; 177 const char *fname; 178 int f; 179 int e; 180 181 memory[fd] = 0; 182 switch (redir->nfile.type) { 183 case NFROM: 184 fname = redir->nfile.expfname; 185 if ((f = open(fname, O_RDONLY)) < 0) 186 error("cannot open %s: %s", fname, strerror(errno)); 187 break; 188 case NFROMTO: 189 fname = redir->nfile.expfname; 190 if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0) 191 error("cannot create %s: %s", fname, strerror(errno)); 192 break; 193 case NTO: 194 if (Cflag) { 195 fname = redir->nfile.expfname; 196 if (stat(fname, &sb) == -1) { 197 if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0) 198 error("cannot create %s: %s", fname, strerror(errno)); 199 } else if (!S_ISREG(sb.st_mode)) { 200 if ((f = open(fname, O_WRONLY, 0666)) < 0) 201 error("cannot create %s: %s", fname, strerror(errno)); 202 if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) { 203 close(f); 204 error("cannot create %s: %s", fname, 205 strerror(EEXIST)); 206 } 207 } else 208 error("cannot create %s: %s", fname, 209 strerror(EEXIST)); 210 break; 211 } 212 /* FALLTHROUGH */ 213 case NCLOBBER: 214 fname = redir->nfile.expfname; 215 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 216 error("cannot create %s: %s", fname, strerror(errno)); 217 break; 218 case NAPPEND: 219 fname = redir->nfile.expfname; 220 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) 221 error("cannot create %s: %s", fname, strerror(errno)); 222 break; 223 case NTOFD: 224 case NFROMFD: 225 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */ 226 if (memory[redir->ndup.dupfd]) 227 memory[fd] = 1; 228 else { 229 if (dup2(redir->ndup.dupfd, fd) < 0) 230 error("%d: %s", redir->ndup.dupfd, 231 strerror(errno)); 232 } 233 } else { 234 close(fd); 235 } 236 return; 237 case NHERE: 238 case NXHERE: 239 f = openhere(redir); 240 break; 241 default: 242 abort(); 243 } 244 if (f != fd) { 245 if (dup2(f, fd) == -1) { 246 e = errno; 247 close(f); 248 error("%d: %s", fd, strerror(e)); 249 } 250 close(f); 251 } 252 } 253 254 255 /* 256 * Handle here documents. Normally we fork off a process to write the 257 * data to a pipe. If the document is short, we can stuff the data in 258 * the pipe without forking. 259 */ 260 261 static int 262 openhere(union node *redir) 263 { 264 const char *p; 265 int pip[2]; 266 size_t len = 0; 267 int flags; 268 ssize_t written = 0; 269 270 if (pipe(pip) < 0) 271 error("Pipe call failed: %s", strerror(errno)); 272 273 if (redir->type == NXHERE) 274 p = redir->nhere.expdoc; 275 else 276 p = redir->nhere.doc->narg.text; 277 len = strlen(p); 278 if (len == 0) 279 goto out; 280 flags = fcntl(pip[1], F_GETFL, 0); 281 if (flags != -1 && fcntl(pip[1], F_SETFL, flags | O_NONBLOCK) != -1) { 282 written = write(pip[1], p, len); 283 if (written < 0) 284 written = 0; 285 if ((size_t)written == len) 286 goto out; 287 fcntl(pip[1], F_SETFL, flags); 288 } 289 290 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) { 291 close(pip[0]); 292 signal(SIGINT, SIG_IGN); 293 signal(SIGQUIT, SIG_IGN); 294 signal(SIGHUP, SIG_IGN); 295 signal(SIGTSTP, SIG_IGN); 296 signal(SIGPIPE, SIG_DFL); 297 xwrite(pip[1], p + written, len - written); 298 _exit(0); 299 } 300 out: 301 close(pip[1]); 302 return pip[0]; 303 } 304 305 306 307 /* 308 * Undo the effects of the last redirection. 309 */ 310 311 void 312 popredir(void) 313 { 314 struct redirtab *rp = redirlist; 315 int i; 316 317 INTOFF; 318 if (empty_redirs > 0) { 319 empty_redirs--; 320 INTON; 321 return; 322 } 323 for (i = 0 ; i < 10 ; i++) { 324 if (rp->renamed[i] != EMPTY) { 325 if (rp->renamed[i] >= 0) { 326 dup2(rp->renamed[i], i); 327 close(rp->renamed[i]); 328 } else { 329 close(i); 330 } 331 } 332 } 333 fd0_redirected = rp->fd0_redirected; 334 empty_redirs = rp->empty_redirs; 335 redirlist = rp->next; 336 ckfree(rp); 337 INTON; 338 } 339 340 /* Return true if fd 0 has already been redirected at least once. */ 341 int 342 fd0_redirected_p(void) 343 { 344 return fd0_redirected != 0; 345 } 346 347 /* 348 * Discard all saved file descriptors. 349 */ 350 351 void 352 clearredir(void) 353 { 354 struct redirtab *rp; 355 int i; 356 357 for (rp = redirlist ; rp ; rp = rp->next) { 358 for (i = 0 ; i < 10 ; i++) { 359 if (rp->renamed[i] >= 0) { 360 close(rp->renamed[i]); 361 } 362 rp->renamed[i] = EMPTY; 363 } 364 } 365 } 366