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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * $Id: redir.c,v 1.8 1997/02/22 13:58:43 peter Exp $ 37 */ 38 39 #ifndef lint 40 static char const sccsid[] = "@(#)redir.c 8.2 (Berkeley) 5/4/95"; 41 #endif /* not lint */ 42 43 #include <sys/types.h> 44 #include <signal.h> 45 #include <string.h> 46 #include <fcntl.h> 47 #include <errno.h> 48 #include <unistd.h> 49 #include <stdlib.h> 50 51 /* 52 * Code for dealing with input/output redirection. 53 */ 54 55 #include "shell.h" 56 #include "nodes.h" 57 #include "jobs.h" 58 #include "expand.h" 59 #include "redir.h" 60 #include "output.h" 61 #include "memalloc.h" 62 #include "error.h" 63 64 65 #define EMPTY -2 /* marks an unused slot in redirtab */ 66 #define PIPESIZE 4096 /* amount of buffering in a pipe */ 67 68 69 MKINIT 70 struct redirtab { 71 struct redirtab *next; 72 short 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 int fd0_redirected = 0; 84 85 STATIC void openredirect __P((union node *, char[10 ])); 86 STATIC int openhere __P((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(redir, flags) 99 union node *redir; 100 int flags; 101 { 102 union node *n; 103 struct redirtab *sv = NULL; 104 int i; 105 int fd; 106 int try; 107 char memory[10]; /* file descriptors to write to memory */ 108 109 for (i = 10 ; --i >= 0 ; ) 110 memory[i] = 0; 111 memory[1] = flags & REDIR_BACKQ; 112 if (flags & REDIR_PUSH) { 113 sv = ckmalloc(sizeof (struct redirtab)); 114 for (i = 0 ; i < 10 ; i++) 115 sv->renamed[i] = EMPTY; 116 sv->next = redirlist; 117 redirlist = sv; 118 } 119 for (n = redir ; n ; n = n->nfile.next) { 120 fd = n->nfile.fd; 121 try = 0; 122 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) && 123 n->ndup.dupfd == fd) 124 continue; /* redirect from/to same file descriptor */ 125 126 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { 127 INTOFF; 128 again: 129 if ((i = fcntl(fd, F_DUPFD, 10)) == -1) { 130 switch (errno) { 131 case EBADF: 132 if (!try) { 133 openredirect(n, memory); 134 try++; 135 goto again; 136 } 137 /* FALLTHROUGH*/ 138 default: 139 INTON; 140 error("%d: %s", fd, strerror(errno)); 141 break; 142 } 143 } 144 if (!try) { 145 sv->renamed[fd] = i; 146 close(fd); 147 } 148 INTON; 149 } else { 150 close(fd); 151 } 152 if (fd == 0) 153 fd0_redirected++; 154 if (!try) 155 openredirect(n, memory); 156 } 157 if (memory[1]) 158 out1 = &memout; 159 if (memory[2]) 160 out2 = &memout; 161 } 162 163 164 STATIC void 165 openredirect(redir, memory) 166 union node *redir; 167 char memory[10]; 168 { 169 int fd = redir->nfile.fd; 170 char *fname; 171 int f; 172 173 /* 174 * We suppress interrupts so that we won't leave open file 175 * descriptors around. This may not be such a good idea because 176 * an open of a device or a fifo can block indefinitely. 177 */ 178 INTOFF; 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, errmsg(errno, E_OPEN)); 185 movefd: 186 if (f != fd) { 187 copyfd(f, fd); 188 close(f); 189 } 190 break; 191 case NTO: 192 fname = redir->nfile.expfname; 193 #ifdef O_CREAT 194 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 195 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 196 #else 197 if ((f = creat(fname, 0666)) < 0) 198 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 199 #endif 200 goto movefd; 201 case NAPPEND: 202 fname = redir->nfile.expfname; 203 #ifdef O_APPEND 204 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) 205 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 206 #else 207 if ((f = open(fname, O_WRONLY)) < 0 208 && (f = creat(fname, 0666)) < 0) 209 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 210 lseek(f, (off_t)0, 2); 211 #endif 212 goto movefd; 213 case NTOFD: 214 case NFROMFD: 215 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */ 216 if (memory[redir->ndup.dupfd]) 217 memory[fd] = 1; 218 else 219 copyfd(redir->ndup.dupfd, fd); 220 } 221 break; 222 case NHERE: 223 case NXHERE: 224 f = openhere(redir); 225 goto movefd; 226 default: 227 abort(); 228 } 229 INTON; 230 } 231 232 233 /* 234 * Handle here documents. Normally we fork off a process to write the 235 * data to a pipe. If the document is short, we can stuff the data in 236 * the pipe without forking. 237 */ 238 239 STATIC int 240 openhere(redir) 241 union node *redir; 242 { 243 int pip[2]; 244 int len = 0; 245 246 if (pipe(pip) < 0) 247 error("Pipe call failed"); 248 if (redir->type == NHERE) { 249 len = strlen(redir->nhere.doc->narg.text); 250 if (len <= PIPESIZE) { 251 xwrite(pip[1], redir->nhere.doc->narg.text, len); 252 goto out; 253 } 254 } 255 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) { 256 close(pip[0]); 257 signal(SIGINT, SIG_IGN); 258 signal(SIGQUIT, SIG_IGN); 259 signal(SIGHUP, SIG_IGN); 260 #ifdef SIGTSTP 261 signal(SIGTSTP, SIG_IGN); 262 #endif 263 signal(SIGPIPE, SIG_DFL); 264 if (redir->type == NHERE) 265 xwrite(pip[1], redir->nhere.doc->narg.text, len); 266 else 267 expandhere(redir->nhere.doc, pip[1]); 268 _exit(0); 269 } 270 out: 271 close(pip[1]); 272 return pip[0]; 273 } 274 275 276 277 /* 278 * Undo the effects of the last redirection. 279 */ 280 281 void 282 popredir() { 283 struct redirtab *rp = redirlist; 284 int i; 285 286 for (i = 0 ; i < 10 ; i++) { 287 if (rp->renamed[i] != EMPTY) { 288 if (i == 0) 289 fd0_redirected--; 290 close(i); 291 if (rp->renamed[i] >= 0) { 292 copyfd(rp->renamed[i], i); 293 close(rp->renamed[i]); 294 } 295 } 296 } 297 INTOFF; 298 redirlist = rp->next; 299 ckfree(rp); 300 INTON; 301 } 302 303 /* 304 * Undo all redirections. Called on error or interrupt. 305 */ 306 307 #ifdef mkinit 308 309 INCLUDE "redir.h" 310 311 RESET { 312 while (redirlist) 313 popredir(); 314 } 315 316 SHELLPROC { 317 clearredir(); 318 } 319 320 #endif 321 322 /* Return true if fd 0 has already been redirected at least once. */ 323 int 324 fd0_redirected_p () { 325 return fd0_redirected != 0; 326 } 327 328 /* 329 * Discard all saved file descriptors. 330 */ 331 332 void 333 clearredir() { 334 struct redirtab *rp; 335 int i; 336 337 for (rp = redirlist ; rp ; rp = rp->next) { 338 for (i = 0 ; i < 10 ; i++) { 339 if (rp->renamed[i] >= 0) { 340 close(rp->renamed[i]); 341 } 342 rp->renamed[i] = EMPTY; 343 } 344 } 345 } 346 347 348 349 /* 350 * Copy a file descriptor to be >= to. Returns -1 351 * if the source file descriptor is closed, EMPTY if there are no unused 352 * file descriptors left. 353 */ 354 355 int 356 copyfd(from, to) 357 int from; 358 int to; 359 { 360 int newfd; 361 362 newfd = fcntl(from, F_DUPFD, to); 363 if (newfd < 0) { 364 if (errno == EMFILE) 365 return EMPTY; 366 else 367 error("%d: %s", from, strerror(errno)); 368 } 369 return newfd; 370 } 371