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