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