1 /* $NetBSD: redir.c,v 1.16 1997/07/04 21:02:21 christos 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 1.16 1997/07/04 21:02:21 christos Exp $"); 45 #endif 46 #endif /* not lint */ 47 48 #include <sys/types.h> 49 #include <signal.h> 50 #include <string.h> 51 #include <fcntl.h> 52 #include <errno.h> 53 #include <unistd.h> 54 #include <stdlib.h> 55 56 /* 57 * Code for dealing with input/output redirection. 58 */ 59 60 #include "shell.h" 61 #include "nodes.h" 62 #include "jobs.h" 63 #include "expand.h" 64 #include "redir.h" 65 #include "output.h" 66 #include "memalloc.h" 67 #include "error.h" 68 69 70 #define EMPTY -2 /* marks an unused slot in redirtab */ 71 #define PIPESIZE 4096 /* amount of buffering in a pipe */ 72 73 74 MKINIT 75 struct redirtab { 76 struct redirtab *next; 77 short renamed[10]; 78 }; 79 80 81 MKINIT struct redirtab *redirlist; 82 83 /* 84 * We keep track of whether or not fd0 has been redirected. This is for 85 * background commands, where we want to redirect fd0 to /dev/null only 86 * if it hasn't already been redirected. 87 */ 88 int fd0_redirected = 0; 89 90 STATIC void openredirect __P((union node *, char[10 ])); 91 STATIC int openhere __P((union node *)); 92 93 94 /* 95 * Process a list of redirection commands. If the REDIR_PUSH flag is set, 96 * old file descriptors are stashed away so that the redirection can be 97 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the 98 * standard output, and the standard error if it becomes a duplicate of 99 * stdout, is saved in memory. 100 */ 101 102 void 103 redirect(redir, flags) 104 union node *redir; 105 int flags; 106 { 107 union node *n; 108 struct redirtab *sv = NULL; 109 int i; 110 int fd; 111 int try; 112 char memory[10]; /* file descriptors to write to memory */ 113 114 for (i = 10 ; --i >= 0 ; ) 115 memory[i] = 0; 116 memory[1] = flags & REDIR_BACKQ; 117 if (flags & REDIR_PUSH) { 118 sv = ckmalloc(sizeof (struct redirtab)); 119 for (i = 0 ; i < 10 ; i++) 120 sv->renamed[i] = EMPTY; 121 sv->next = redirlist; 122 redirlist = sv; 123 } 124 for (n = redir ; n ; n = n->nfile.next) { 125 fd = n->nfile.fd; 126 try = 0; 127 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) && 128 n->ndup.dupfd == fd) 129 continue; /* redirect from/to same file descriptor */ 130 131 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { 132 INTOFF; 133 again: 134 if ((i = fcntl(fd, F_DUPFD, 10)) == -1) { 135 switch (errno) { 136 case EBADF: 137 if (!try) { 138 openredirect(n, memory); 139 try++; 140 goto again; 141 } 142 /* FALLTHROUGH*/ 143 default: 144 INTON; 145 error("%d: %s", fd, strerror(errno)); 146 break; 147 } 148 } 149 if (!try) { 150 sv->renamed[fd] = i; 151 close(fd); 152 } 153 INTON; 154 } else { 155 close(fd); 156 } 157 if (fd == 0) 158 fd0_redirected++; 159 if (!try) 160 openredirect(n, memory); 161 } 162 if (memory[1]) 163 out1 = &memout; 164 if (memory[2]) 165 out2 = &memout; 166 } 167 168 169 STATIC void 170 openredirect(redir, memory) 171 union node *redir; 172 char memory[10]; 173 { 174 int fd = redir->nfile.fd; 175 char *fname; 176 int f; 177 178 /* 179 * We suppress interrupts so that we won't leave open file 180 * descriptors around. This may not be such a good idea because 181 * an open of a device or a fifo can block indefinitely. 182 */ 183 INTOFF; 184 memory[fd] = 0; 185 switch (redir->nfile.type) { 186 case NFROM: 187 fname = redir->nfile.expfname; 188 if ((f = open(fname, O_RDONLY)) < 0) 189 error("cannot open %s: %s", fname, errmsg(errno, E_OPEN)); 190 movefd: 191 if (f != fd) { 192 copyfd(f, fd); 193 close(f); 194 } 195 break; 196 case NTO: 197 fname = redir->nfile.expfname; 198 #ifdef O_CREAT 199 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 200 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 201 #else 202 if ((f = creat(fname, 0666)) < 0) 203 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 204 #endif 205 goto movefd; 206 case NAPPEND: 207 fname = redir->nfile.expfname; 208 #ifdef O_APPEND 209 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) 210 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 211 #else 212 if ((f = open(fname, O_WRONLY)) < 0 213 && (f = creat(fname, 0666)) < 0) 214 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 215 lseek(f, (off_t)0, 2); 216 #endif 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 copyfd(redir->ndup.dupfd, fd); 225 } 226 break; 227 case NHERE: 228 case NXHERE: 229 f = openhere(redir); 230 goto movefd; 231 default: 232 abort(); 233 } 234 INTON; 235 } 236 237 238 /* 239 * Handle here documents. Normally we fork off a process to write the 240 * data to a pipe. If the document is short, we can stuff the data in 241 * the pipe without forking. 242 */ 243 244 STATIC int 245 openhere(redir) 246 union node *redir; 247 { 248 int pip[2]; 249 int len = 0; 250 251 if (pipe(pip) < 0) 252 error("Pipe call failed"); 253 if (redir->type == NHERE) { 254 len = strlen(redir->nhere.doc->narg.text); 255 if (len <= PIPESIZE) { 256 xwrite(pip[1], redir->nhere.doc->narg.text, len); 257 goto out; 258 } 259 } 260 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) { 261 close(pip[0]); 262 signal(SIGINT, SIG_IGN); 263 signal(SIGQUIT, SIG_IGN); 264 signal(SIGHUP, SIG_IGN); 265 #ifdef SIGTSTP 266 signal(SIGTSTP, SIG_IGN); 267 #endif 268 signal(SIGPIPE, SIG_DFL); 269 if (redir->type == NHERE) 270 xwrite(pip[1], redir->nhere.doc->narg.text, len); 271 else 272 expandhere(redir->nhere.doc, pip[1]); 273 _exit(0); 274 } 275 out: 276 close(pip[1]); 277 return pip[0]; 278 } 279 280 281 282 /* 283 * Undo the effects of the last redirection. 284 */ 285 286 void 287 popredir() { 288 struct redirtab *rp = redirlist; 289 int i; 290 291 for (i = 0 ; i < 10 ; i++) { 292 if (rp->renamed[i] != EMPTY) { 293 if (i == 0) 294 fd0_redirected--; 295 close(i); 296 if (rp->renamed[i] >= 0) { 297 copyfd(rp->renamed[i], i); 298 close(rp->renamed[i]); 299 } 300 } 301 } 302 INTOFF; 303 redirlist = rp->next; 304 ckfree(rp); 305 INTON; 306 } 307 308 /* 309 * Undo all redirections. Called on error or interrupt. 310 */ 311 312 #ifdef mkinit 313 314 INCLUDE "redir.h" 315 316 RESET { 317 while (redirlist) 318 popredir(); 319 } 320 321 SHELLPROC { 322 clearredir(); 323 } 324 325 #endif 326 327 /* Return true if fd 0 has already been redirected at least once. */ 328 int 329 fd0_redirected_p () { 330 return fd0_redirected != 0; 331 } 332 333 /* 334 * Discard all saved file descriptors. 335 */ 336 337 void 338 clearredir() { 339 struct redirtab *rp; 340 int i; 341 342 for (rp = redirlist ; rp ; rp = rp->next) { 343 for (i = 0 ; i < 10 ; i++) { 344 if (rp->renamed[i] >= 0) { 345 close(rp->renamed[i]); 346 } 347 rp->renamed[i] = EMPTY; 348 } 349 } 350 } 351 352 353 354 /* 355 * Copy a file descriptor to be >= to. Returns -1 356 * if the source file descriptor is closed, EMPTY if there are no unused 357 * file descriptors left. 358 */ 359 360 int 361 copyfd(from, to) 362 int from; 363 int to; 364 { 365 int newfd; 366 367 newfd = fcntl(from, F_DUPFD, to); 368 if (newfd < 0) { 369 if (errno == EMFILE) 370 return EMPTY; 371 else 372 error("%d: %s", from, strerror(errno)); 373 } 374 return newfd; 375 } 376