1 /* $NetBSD: redir.c,v 1.22 2000/05/22 10:18:47 elric Exp $ */ 2 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. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #ifndef lint 41 #if 0 42 static char sccsid[] = "@(#)redir.c 8.2 (Berkeley) 5/4/95"; 43 #else 44 __RCSID("$NetBSD: redir.c,v 1.22 2000/05/22 10:18:47 elric Exp $"); 45 #endif 46 #endif /* not lint */ 47 48 #include <sys/types.h> 49 #include <sys/param.h> /* PIPE_BUF */ 50 #include <signal.h> 51 #include <string.h> 52 #include <fcntl.h> 53 #include <errno.h> 54 #include <unistd.h> 55 #include <stdlib.h> 56 57 /* 58 * Code for dealing with input/output redirection. 59 */ 60 61 #include "shell.h" 62 #include "nodes.h" 63 #include "jobs.h" 64 #include "expand.h" 65 #include "redir.h" 66 #include "output.h" 67 #include "memalloc.h" 68 #include "error.h" 69 70 71 #define EMPTY -2 /* marks an unused slot in redirtab */ 72 #ifndef PIPE_BUF 73 # define PIPESIZE 4096 /* amount of buffering in a pipe */ 74 #else 75 # define PIPESIZE PIPE_BUF 76 #endif 77 78 79 MKINIT 80 struct redirtab { 81 struct redirtab *next; 82 short renamed[10]; 83 }; 84 85 86 MKINIT struct redirtab *redirlist; 87 88 /* 89 * We keep track of whether or not fd0 has been redirected. This is for 90 * background commands, where we want to redirect fd0 to /dev/null only 91 * if it hasn't already been redirected. 92 */ 93 int fd0_redirected = 0; 94 95 STATIC void openredirect __P((union node *, char[10 ])); 96 STATIC int openhere __P((union node *)); 97 98 99 /* 100 * Process a list of redirection commands. If the REDIR_PUSH flag is set, 101 * old file descriptors are stashed away so that the redirection can be 102 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the 103 * standard output, and the standard error if it becomes a duplicate of 104 * stdout, is saved in memory. 105 */ 106 107 void 108 redirect(redir, flags) 109 union node *redir; 110 int flags; 111 { 112 union node *n; 113 struct redirtab *sv = NULL; 114 int i; 115 int fd; 116 int try; 117 char memory[10]; /* file descriptors to write to memory */ 118 119 for (i = 10 ; --i >= 0 ; ) 120 memory[i] = 0; 121 memory[1] = flags & REDIR_BACKQ; 122 if (flags & REDIR_PUSH) { 123 sv = ckmalloc(sizeof (struct redirtab)); 124 for (i = 0 ; i < 10 ; i++) 125 sv->renamed[i] = EMPTY; 126 sv->next = redirlist; 127 redirlist = sv; 128 } 129 for (n = redir ; n ; n = n->nfile.next) { 130 fd = n->nfile.fd; 131 try = 0; 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 again: 139 if ((i = fcntl(fd, F_DUPFD, 10)) == -1) { 140 switch (errno) { 141 case EBADF: 142 if (!try) { 143 openredirect(n, memory); 144 try++; 145 goto again; 146 } 147 /* FALLTHROUGH*/ 148 default: 149 INTON; 150 error("%d: %s", fd, strerror(errno)); 151 /* NOTREACHED */ 152 } 153 } 154 if (!try) { 155 sv->renamed[fd] = i; 156 close(fd); 157 } 158 INTON; 159 } else { 160 close(fd); 161 } 162 if (fd == 0) 163 fd0_redirected++; 164 if (!try) 165 openredirect(n, memory); 166 } 167 if (memory[1]) 168 out1 = &memout; 169 if (memory[2]) 170 out2 = &memout; 171 } 172 173 174 STATIC void 175 openredirect(redir, memory) 176 union node *redir; 177 char memory[10]; 178 { 179 int fd = redir->nfile.fd; 180 char *fname; 181 int f; 182 183 /* 184 * We suppress interrupts so that we won't leave open file 185 * descriptors around. This may not be such a good idea because 186 * an open of a device or a fifo can block indefinitely. 187 */ 188 INTOFF; 189 memory[fd] = 0; 190 switch (redir->nfile.type) { 191 case NFROM: 192 fname = redir->nfile.expfname; 193 if ((f = open(fname, O_RDONLY)) < 0) 194 goto eopen; 195 break; 196 case NFROMTO: 197 fname = redir->nfile.expfname; 198 if ((f = open(fname, O_RDWR|O_CREAT|O_TRUNC, 0666)) < 0) 199 goto ecreate; 200 break; 201 case NTO: 202 fname = redir->nfile.expfname; 203 #ifdef O_CREAT 204 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 205 goto ecreate; 206 #else 207 if ((f = creat(fname, 0666)) < 0) 208 goto ecreate; 209 #endif 210 break; 211 case NAPPEND: 212 fname = redir->nfile.expfname; 213 #ifdef O_APPEND 214 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) 215 goto ecreate; 216 #else 217 if ((f = open(fname, O_WRONLY)) < 0 218 && (f = creat(fname, 0666)) < 0) 219 goto ecreate; 220 lseek(f, (off_t)0, 2); 221 #endif 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 copyfd(redir->ndup.dupfd, fd); 230 } 231 INTON; 232 return; 233 case NHERE: 234 case NXHERE: 235 f = openhere(redir); 236 break; 237 default: 238 abort(); 239 } 240 241 if (f != fd) { 242 copyfd(f, fd); 243 close(f); 244 } 245 INTON; 246 return; 247 ecreate: 248 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 249 eopen: 250 error("cannot open %s: %s", fname, errmsg(errno, E_OPEN)); 251 } 252 253 254 /* 255 * Handle here documents. Normally we fork off a process to write the 256 * data to a pipe. If the document is short, we can stuff the data in 257 * the pipe without forking. 258 */ 259 260 STATIC int 261 openhere(redir) 262 union node *redir; 263 { 264 int pip[2]; 265 int len = 0; 266 267 if (pipe(pip) < 0) 268 error("Pipe call failed"); 269 if (redir->type == NHERE) { 270 len = strlen(redir->nhere.doc->narg.text); 271 if (len <= PIPESIZE) { 272 xwrite(pip[1], redir->nhere.doc->narg.text, len); 273 goto out; 274 } 275 } 276 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) { 277 close(pip[0]); 278 signal(SIGINT, SIG_IGN); 279 signal(SIGQUIT, SIG_IGN); 280 signal(SIGHUP, SIG_IGN); 281 #ifdef SIGTSTP 282 signal(SIGTSTP, SIG_IGN); 283 #endif 284 signal(SIGPIPE, SIG_DFL); 285 if (redir->type == NHERE) 286 xwrite(pip[1], redir->nhere.doc->narg.text, len); 287 else 288 expandhere(redir->nhere.doc, pip[1]); 289 _exit(0); 290 } 291 out: 292 close(pip[1]); 293 return pip[0]; 294 } 295 296 297 298 /* 299 * Undo the effects of the last redirection. 300 */ 301 302 void 303 popredir() { 304 struct redirtab *rp = redirlist; 305 int i; 306 307 for (i = 0 ; i < 10 ; i++) { 308 if (rp->renamed[i] != EMPTY) { 309 if (i == 0) 310 fd0_redirected--; 311 close(i); 312 if (rp->renamed[i] >= 0) { 313 copyfd(rp->renamed[i], i); 314 close(rp->renamed[i]); 315 } 316 } 317 } 318 INTOFF; 319 redirlist = rp->next; 320 ckfree(rp); 321 INTON; 322 } 323 324 /* 325 * Undo all redirections. Called on error or interrupt. 326 */ 327 328 #ifdef mkinit 329 330 INCLUDE "redir.h" 331 332 RESET { 333 while (redirlist) 334 popredir(); 335 } 336 337 SHELLPROC { 338 clearredir(); 339 } 340 341 #endif 342 343 /* Return true if fd 0 has already been redirected at least once. */ 344 int 345 fd0_redirected_p () { 346 return fd0_redirected != 0; 347 } 348 349 /* 350 * Discard all saved file descriptors. 351 */ 352 353 void 354 clearredir() { 355 struct redirtab *rp; 356 int i; 357 358 for (rp = redirlist ; rp ; rp = rp->next) { 359 for (i = 0 ; i < 10 ; i++) { 360 if (rp->renamed[i] >= 0) { 361 close(rp->renamed[i]); 362 } 363 rp->renamed[i] = EMPTY; 364 } 365 } 366 } 367 368 369 370 /* 371 * Copy a file descriptor to be >= to. Returns -1 372 * if the source file descriptor is closed, EMPTY if there are no unused 373 * file descriptors left. 374 */ 375 376 int 377 copyfd(from, to) 378 int from; 379 int to; 380 { 381 int newfd; 382 383 newfd = fcntl(from, F_DUPFD, to); 384 if (newfd < 0) { 385 if (errno == EMFILE) 386 return EMPTY; 387 else 388 error("%d: %s", from, strerror(errno)); 389 } 390 return newfd; 391 } 392