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 37 #ifndef lint 38 #if 0 39 static char sccsid[] = "@(#)redir.c 8.2 (Berkeley) 5/4/95"; 40 #endif 41 #endif /* not lint */ 42 #include <sys/cdefs.h> 43 __FBSDID("$FreeBSD$"); 44 45 #include <sys/types.h> 46 #include <sys/stat.h> 47 #include <signal.h> 48 #include <string.h> 49 #include <fcntl.h> 50 #include <errno.h> 51 #include <unistd.h> 52 #include <stdlib.h> 53 54 /* 55 * Code for dealing with input/output redirection. 56 */ 57 58 #include "shell.h" 59 #include "nodes.h" 60 #include "jobs.h" 61 #include "expand.h" 62 #include "redir.h" 63 #include "output.h" 64 #include "memalloc.h" 65 #include "error.h" 66 #include "options.h" 67 68 69 #define EMPTY -2 /* marks an unused slot in redirtab */ 70 #define PIPESIZE 4096 /* amount of buffering in a pipe */ 71 72 73 MKINIT 74 struct redirtab { 75 struct redirtab *next; 76 int renamed[10]; 77 }; 78 79 80 MKINIT struct redirtab *redirlist; 81 82 /* 83 * We keep track of whether or not fd0 has been redirected. This is for 84 * background commands, where we want to redirect fd0 to /dev/null only 85 * if it hasn't already been redirected. 86 */ 87 STATIC int fd0_redirected = 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 */ 100 101 void 102 redirect(union node *redir, int flags) 103 { 104 union node *n; 105 struct redirtab *sv = NULL; 106 int i; 107 int fd; 108 int try; 109 char memory[10]; /* file descriptors to write to memory */ 110 111 for (i = 10 ; --i >= 0 ; ) 112 memory[i] = 0; 113 memory[1] = flags & REDIR_BACKQ; 114 if (flags & REDIR_PUSH) { 115 sv = ckmalloc(sizeof (struct redirtab)); 116 for (i = 0 ; i < 10 ; i++) 117 sv->renamed[i] = EMPTY; 118 sv->next = redirlist; 119 redirlist = sv; 120 } 121 for (n = redir ; n ; n = n->nfile.next) { 122 fd = n->nfile.fd; 123 try = 0; 124 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) && 125 n->ndup.dupfd == fd) 126 continue; /* redirect from/to same file descriptor */ 127 128 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { 129 INTOFF; 130 again: 131 if ((i = fcntl(fd, F_DUPFD, 10)) == -1) { 132 switch (errno) { 133 case EBADF: 134 if (!try) { 135 openredirect(n, memory); 136 try++; 137 goto again; 138 } 139 /* FALLTHROUGH*/ 140 default: 141 INTON; 142 error("%d: %s", fd, strerror(errno)); 143 break; 144 } 145 } 146 if (!try) { 147 sv->renamed[fd] = i; 148 } 149 INTON; 150 } 151 if (fd == 0) 152 fd0_redirected++; 153 if (!try) 154 openredirect(n, memory); 155 } 156 if (memory[1]) 157 out1 = &memout; 158 if (memory[2]) 159 out2 = &memout; 160 } 161 162 163 STATIC void 164 openredirect(union node *redir, char memory[10]) 165 { 166 struct stat sb; 167 int fd = redir->nfile.fd; 168 char *fname; 169 int f; 170 171 /* 172 * We suppress interrupts so that we won't leave open file 173 * descriptors around. This may not be such a good idea because 174 * an open of a device or a fifo can block indefinitely. 175 */ 176 INTOFF; 177 memory[fd] = 0; 178 switch (redir->nfile.type) { 179 case NFROM: 180 fname = redir->nfile.expfname; 181 if ((f = open(fname, O_RDONLY)) < 0) 182 error("cannot open %s: %s", fname, strerror(errno)); 183 movefd: 184 if (f != fd) { 185 close(fd); 186 copyfd(f, fd); 187 close(f); 188 } 189 break; 190 case NFROMTO: 191 fname = redir->nfile.expfname; 192 if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0) 193 error("cannot create %s: %s", fname, strerror(errno)); 194 goto movefd; 195 case NTO: 196 fname = redir->nfile.expfname; 197 if (Cflag && stat(fname, &sb) != -1 && S_ISREG(sb.st_mode)) 198 error("cannot create %s: %s", fname, 199 strerror(EEXIST)); 200 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 201 error("cannot create %s: %s", fname, strerror(errno)); 202 goto movefd; 203 case NCLOBBER: 204 fname = redir->nfile.expfname; 205 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 206 error("cannot create %s: %s", fname, strerror(errno)); 207 goto movefd; 208 case NAPPEND: 209 fname = redir->nfile.expfname; 210 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) 211 error("cannot create %s: %s", fname, strerror(errno)); 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 close(fd); 220 copyfd(redir->ndup.dupfd, fd); 221 } 222 } else 223 close(fd); 224 break; 225 case NHERE: 226 case NXHERE: 227 f = openhere(redir); 228 goto movefd; 229 default: 230 abort(); 231 } 232 INTON; 233 } 234 235 236 /* 237 * Handle here documents. Normally we fork off a process to write the 238 * data to a pipe. If the document is short, we can stuff the data in 239 * the pipe without forking. 240 */ 241 242 STATIC int 243 openhere(union node *redir) 244 { 245 int pip[2]; 246 int len = 0; 247 248 if (pipe(pip) < 0) 249 error("Pipe call failed: %s", strerror(errno)); 250 if (redir->type == NHERE) { 251 len = strlen(redir->nhere.doc->narg.text); 252 if (len <= PIPESIZE) { 253 xwrite(pip[1], redir->nhere.doc->narg.text, len); 254 goto out; 255 } 256 } 257 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) { 258 close(pip[0]); 259 signal(SIGINT, SIG_IGN); 260 signal(SIGQUIT, SIG_IGN); 261 signal(SIGHUP, SIG_IGN); 262 signal(SIGTSTP, SIG_IGN); 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(void) 283 { 284 struct redirtab *rp = redirlist; 285 int i; 286 287 for (i = 0 ; i < 10 ; i++) { 288 if (rp->renamed[i] != EMPTY) { 289 if (i == 0) 290 fd0_redirected--; 291 close(i); 292 if (rp->renamed[i] >= 0) { 293 copyfd(rp->renamed[i], i); 294 close(rp->renamed[i]); 295 } 296 } 297 } 298 INTOFF; 299 redirlist = rp->next; 300 ckfree(rp); 301 INTON; 302 } 303 304 /* 305 * Undo all redirections. Called on error or interrupt. 306 */ 307 308 #ifdef mkinit 309 310 INCLUDE "redir.h" 311 312 RESET { 313 while (redirlist) 314 popredir(); 315 } 316 317 SHELLPROC { 318 clearredir(); 319 } 320 321 #endif 322 323 /* Return true if fd 0 has already been redirected at least once. */ 324 int 325 fd0_redirected_p(void) 326 { 327 return fd0_redirected != 0; 328 } 329 330 /* 331 * Discard all saved file descriptors. 332 */ 333 334 void 335 clearredir(void) 336 { 337 struct redirtab *rp; 338 int i; 339 340 for (rp = redirlist ; rp ; rp = rp->next) { 341 for (i = 0 ; i < 10 ; i++) { 342 if (rp->renamed[i] >= 0) { 343 close(rp->renamed[i]); 344 } 345 rp->renamed[i] = EMPTY; 346 } 347 } 348 } 349 350 351 352 /* 353 * Copy a file descriptor to be >= to. Returns -1 354 * if the source file descriptor is closed, EMPTY if there are no unused 355 * file descriptors left. 356 */ 357 358 int 359 copyfd(int from, int to) 360 { 361 int newfd; 362 363 newfd = fcntl(from, F_DUPFD, to); 364 if (newfd < 0) { 365 if (errno == EMFILE) 366 return EMPTY; 367 else 368 error("%d: %s", from, strerror(errno)); 369 } 370 return newfd; 371 } 372