1 /*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Kenneth Almquist. 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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #ifndef lint 34 #if 0 35 static char sccsid[] = "@(#)redir.c 8.2 (Berkeley) 5/4/95"; 36 #endif 37 #endif /* not lint */ 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include <sys/types.h> 42 #include <sys/stat.h> 43 #include <signal.h> 44 #include <string.h> 45 #include <fcntl.h> 46 #include <errno.h> 47 #include <unistd.h> 48 #include <stdlib.h> 49 50 /* 51 * Code for dealing with input/output redirection. 52 */ 53 54 #include "shell.h" 55 #include "nodes.h" 56 #include "jobs.h" 57 #include "expand.h" 58 #include "redir.h" 59 #include "output.h" 60 #include "memalloc.h" 61 #include "error.h" 62 #include "options.h" 63 64 65 #define EMPTY -2 /* marks an unused slot in redirtab */ 66 #define CLOSED -1 /* fd was not open before redir */ 67 68 69 struct redirtab { 70 struct redirtab *next; 71 int renamed[10]; 72 int fd0_redirected; 73 unsigned int empty_redirs; 74 }; 75 76 77 static struct redirtab *redirlist; 78 79 /* 80 * We keep track of whether or not fd0 has been redirected. This is for 81 * background commands, where we want to redirect fd0 to /dev/null only 82 * if it hasn't already been redirected. 83 */ 84 static int fd0_redirected = 0; 85 86 /* Number of redirtabs that have not been allocated. */ 87 static unsigned int empty_redirs = 0; 88 89 static void openredirect(union node *, char[10 ]); 90 static int openhere(union node *); 91 92 93 /* 94 * Process a list of redirection commands. If the REDIR_PUSH flag is set, 95 * old file descriptors are stashed away so that the redirection can be 96 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the 97 * standard output, and the standard error if it becomes a duplicate of 98 * stdout, is saved in memory. 99 * 100 * We suppress interrupts so that we won't leave open file 101 * descriptors around. Because the signal handler remains 102 * installed and we do not use system call restart, interrupts 103 * will still abort blocking opens such as fifos (they will fail 104 * with EINTR). There is, however, a race condition if an interrupt 105 * arrives after INTOFF and before open blocks. 106 */ 107 108 void 109 redirect(union node *redir, int flags) 110 { 111 union node *n; 112 struct redirtab *sv = NULL; 113 int i; 114 int fd; 115 char memory[10]; /* file descriptors to write to memory */ 116 117 INTOFF; 118 for (i = 10 ; --i >= 0 ; ) 119 memory[i] = 0; 120 memory[1] = flags & REDIR_BACKQ; 121 if (flags & REDIR_PUSH) { 122 empty_redirs++; 123 if (redir != NULL) { 124 sv = ckmalloc(sizeof (struct redirtab)); 125 for (i = 0 ; i < 10 ; i++) 126 sv->renamed[i] = EMPTY; 127 sv->fd0_redirected = fd0_redirected; 128 sv->empty_redirs = empty_redirs - 1; 129 sv->next = redirlist; 130 redirlist = sv; 131 empty_redirs = 0; 132 } 133 } 134 for (n = redir ; n ; n = n->nfile.next) { 135 fd = n->nfile.fd; 136 if (fd == 0) 137 fd0_redirected = 1; 138 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) && 139 n->ndup.dupfd == fd) 140 continue; /* redirect from/to same file descriptor */ 141 142 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { 143 INTOFF; 144 if ((i = fcntl(fd, F_DUPFD_CLOEXEC, 10)) == -1) { 145 switch (errno) { 146 case EBADF: 147 i = CLOSED; 148 break; 149 default: 150 INTON; 151 error("%d: %s", fd, strerror(errno)); 152 break; 153 } 154 } 155 sv->renamed[fd] = i; 156 INTON; 157 } 158 openredirect(n, memory); 159 INTON; 160 INTOFF; 161 } 162 if (memory[1]) 163 out1 = &memout; 164 if (memory[2]) 165 out2 = &memout; 166 INTON; 167 } 168 169 170 static void 171 openredirect(union node *redir, char memory[10]) 172 { 173 struct stat sb; 174 int fd = redir->nfile.fd; 175 const char *fname; 176 int f; 177 int e; 178 179 memory[fd] = 0; 180 switch (redir->nfile.type) { 181 case NFROM: 182 fname = redir->nfile.expfname; 183 if ((f = open(fname, O_RDONLY)) < 0) 184 error("cannot open %s: %s", fname, strerror(errno)); 185 break; 186 case NFROMTO: 187 fname = redir->nfile.expfname; 188 if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0) 189 error("cannot create %s: %s", fname, strerror(errno)); 190 break; 191 case NTO: 192 if (Cflag) { 193 fname = redir->nfile.expfname; 194 if (stat(fname, &sb) == -1) { 195 if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0) 196 error("cannot create %s: %s", fname, strerror(errno)); 197 } else if (!S_ISREG(sb.st_mode)) { 198 if ((f = open(fname, O_WRONLY, 0666)) < 0) 199 error("cannot create %s: %s", fname, strerror(errno)); 200 if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) { 201 close(f); 202 error("cannot create %s: %s", fname, 203 strerror(EEXIST)); 204 } 205 } else 206 error("cannot create %s: %s", fname, 207 strerror(EEXIST)); 208 break; 209 } 210 /* FALLTHROUGH */ 211 case NCLOBBER: 212 fname = redir->nfile.expfname; 213 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 214 error("cannot create %s: %s", fname, strerror(errno)); 215 break; 216 case NAPPEND: 217 fname = redir->nfile.expfname; 218 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) 219 error("cannot create %s: %s", fname, strerror(errno)); 220 break; 221 case NTOFD: 222 case NFROMFD: 223 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */ 224 if (memory[redir->ndup.dupfd]) 225 memory[fd] = 1; 226 else { 227 if (dup2(redir->ndup.dupfd, fd) < 0) 228 error("%d: %s", redir->ndup.dupfd, 229 strerror(errno)); 230 } 231 } else { 232 close(fd); 233 } 234 return; 235 case NHERE: 236 case NXHERE: 237 f = openhere(redir); 238 break; 239 default: 240 abort(); 241 } 242 if (f != fd) { 243 if (dup2(f, fd) == -1) { 244 e = errno; 245 close(f); 246 error("%d: %s", fd, strerror(e)); 247 } 248 close(f); 249 } 250 } 251 252 253 /* 254 * Handle here documents. Normally we fork off a process to write the 255 * data to a pipe. If the document is short, we can stuff the data in 256 * the pipe without forking. 257 */ 258 259 static int 260 openhere(union node *redir) 261 { 262 const char *p; 263 int pip[2]; 264 size_t len = 0; 265 int flags; 266 ssize_t written = 0; 267 268 if (pipe(pip) < 0) 269 error("Pipe call failed: %s", strerror(errno)); 270 271 if (redir->type == NXHERE) 272 p = redir->nhere.expdoc; 273 else 274 p = redir->nhere.doc->narg.text; 275 len = strlen(p); 276 if (len == 0) 277 goto out; 278 flags = fcntl(pip[1], F_GETFL, 0); 279 if (flags != -1 && fcntl(pip[1], F_SETFL, flags | O_NONBLOCK) != -1) { 280 written = write(pip[1], p, len); 281 if (written < 0) 282 written = 0; 283 if ((size_t)written == len) 284 goto out; 285 fcntl(pip[1], F_SETFL, flags); 286 } 287 288 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) { 289 close(pip[0]); 290 signal(SIGINT, SIG_IGN); 291 signal(SIGQUIT, SIG_IGN); 292 signal(SIGHUP, SIG_IGN); 293 signal(SIGTSTP, SIG_IGN); 294 signal(SIGPIPE, SIG_DFL); 295 xwrite(pip[1], p + written, len - written); 296 _exit(0); 297 } 298 out: 299 close(pip[1]); 300 return pip[0]; 301 } 302 303 304 305 /* 306 * Undo the effects of the last redirection. 307 */ 308 309 void 310 popredir(void) 311 { 312 struct redirtab *rp = redirlist; 313 int i; 314 315 INTOFF; 316 if (empty_redirs > 0) { 317 empty_redirs--; 318 INTON; 319 return; 320 } 321 for (i = 0 ; i < 10 ; i++) { 322 if (rp->renamed[i] != EMPTY) { 323 if (rp->renamed[i] >= 0) { 324 dup2(rp->renamed[i], i); 325 close(rp->renamed[i]); 326 } else { 327 close(i); 328 } 329 } 330 } 331 fd0_redirected = rp->fd0_redirected; 332 empty_redirs = rp->empty_redirs; 333 redirlist = rp->next; 334 ckfree(rp); 335 INTON; 336 } 337 338 /* Return true if fd 0 has already been redirected at least once. */ 339 int 340 fd0_redirected_p(void) 341 { 342 return fd0_redirected != 0; 343 } 344 345 /* 346 * Discard all saved file descriptors. 347 */ 348 349 void 350 clearredir(void) 351 { 352 struct redirtab *rp; 353 int i; 354 355 for (rp = redirlist ; rp ; rp = rp->next) { 356 for (i = 0 ; i < 10 ; i++) { 357 if (rp->renamed[i] >= 0) { 358 close(rp->renamed[i]); 359 } 360 rp->renamed[i] = EMPTY; 361 } 362 } 363 } 364