1 /* $NetBSD: redir.c,v 1.35 2013/06/27 23:22:04 yamt 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #ifndef lint 37 #if 0 38 static char sccsid[] = "@(#)redir.c 8.2 (Berkeley) 5/4/95"; 39 #else 40 __RCSID("$NetBSD: redir.c,v 1.35 2013/06/27 23:22:04 yamt Exp $"); 41 #endif 42 #endif /* not lint */ 43 44 #include <sys/types.h> 45 #include <sys/param.h> /* PIPE_BUF */ 46 #include <signal.h> 47 #include <string.h> 48 #include <fcntl.h> 49 #include <errno.h> 50 #include <unistd.h> 51 #include <stdlib.h> 52 53 /* 54 * Code for dealing with input/output redirection. 55 */ 56 57 #include "main.h" 58 #include "shell.h" 59 #include "nodes.h" 60 #include "jobs.h" 61 #include "options.h" 62 #include "expand.h" 63 #include "redir.h" 64 #include "output.h" 65 #include "memalloc.h" 66 #include "error.h" 67 68 69 #define EMPTY -2 /* marks an unused slot in redirtab */ 70 #define CLOSED -1 /* fd was not open before redir */ 71 #ifndef PIPE_BUF 72 # define PIPESIZE 4096 /* amount of buffering in a pipe */ 73 #else 74 # define PIPESIZE PIPE_BUF 75 #endif 76 77 78 MKINIT 79 struct redirtab { 80 struct redirtab *next; 81 short renamed[10]; 82 }; 83 84 85 MKINIT struct redirtab *redirlist; 86 87 /* 88 * We keep track of whether or not fd0 has been redirected. This is for 89 * background commands, where we want to redirect fd0 to /dev/null only 90 * if it hasn't already been redirected. 91 */ 92 int fd0_redirected = 0; 93 94 STATIC void openredirect(union node *, char[10], int); 95 STATIC int openhere(const union node *); 96 97 98 /* 99 * Process a list of redirection commands. If the REDIR_PUSH flag is set, 100 * old file descriptors are stashed away so that the redirection can be 101 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the 102 * standard output, and the standard error if it becomes a duplicate of 103 * stdout, is saved in memory. 104 */ 105 106 void 107 redirect(union node *redir, int flags) 108 { 109 union node *n; 110 struct redirtab *sv = NULL; 111 int i; 112 int fd; 113 char memory[10]; /* file descriptors to write to memory */ 114 115 for (i = 10 ; --i >= 0 ; ) 116 memory[i] = 0; 117 memory[1] = flags & REDIR_BACKQ; 118 if (flags & REDIR_PUSH) { 119 /* We don't have to worry about REDIR_VFORK here, as 120 * flags & REDIR_PUSH is never true if REDIR_VFORK is set. 121 */ 122 sv = ckmalloc(sizeof (struct redirtab)); 123 for (i = 0 ; i < 10 ; i++) 124 sv->renamed[i] = EMPTY; 125 sv->next = redirlist; 126 redirlist = sv; 127 } 128 for (n = redir ; n ; n = n->nfile.next) { 129 fd = n->nfile.fd; 130 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) && 131 n->ndup.dupfd == fd) 132 continue; /* redirect from/to same file descriptor */ 133 134 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { 135 INTOFF; 136 if ((i = fcntl(fd, F_DUPFD, 10)) == -1) { 137 switch (errno) { 138 case EBADF: 139 i = CLOSED; 140 break; 141 default: 142 INTON; 143 error("%d: %s", fd, strerror(errno)); 144 /* NOTREACHED */ 145 } 146 } else 147 (void)fcntl(i, F_SETFD, FD_CLOEXEC); 148 sv->renamed[fd] = i; 149 INTON; 150 } else { 151 close(fd); 152 } 153 if (fd == 0) 154 fd0_redirected++; 155 openredirect(n, memory, flags); 156 } 157 if (memory[1]) 158 out1 = &memout; 159 if (memory[2]) 160 out2 = &memout; 161 } 162 163 164 STATIC void 165 openredirect(union node *redir, char memory[10], int flags) 166 { 167 int fd = redir->nfile.fd; 168 char *fname; 169 int f; 170 int oflags = O_WRONLY|O_CREAT|O_TRUNC, eflags; 171 172 /* 173 * We suppress interrupts so that we won't leave open file 174 * descriptors around. This may not be such a good idea because 175 * an open of a device or a fifo can block indefinitely. 176 */ 177 INTOFF; 178 memory[fd] = 0; 179 switch (redir->nfile.type) { 180 case NFROM: 181 fname = redir->nfile.expfname; 182 if (flags & REDIR_VFORK) 183 eflags = O_NONBLOCK; 184 else 185 eflags = 0; 186 if ((f = open(fname, O_RDONLY|eflags)) < 0) 187 goto eopen; 188 if (eflags) 189 (void)fcntl(f, F_SETFL, fcntl(f, F_GETFL, 0) & ~eflags); 190 break; 191 case NFROMTO: 192 fname = redir->nfile.expfname; 193 if ((f = open(fname, O_RDWR|O_CREAT|O_TRUNC, 0666)) < 0) 194 goto ecreate; 195 break; 196 case NTO: 197 if (Cflag) 198 oflags |= O_EXCL; 199 /* FALLTHROUGH */ 200 case NCLOBBER: 201 fname = redir->nfile.expfname; 202 if ((f = open(fname, oflags, 0666)) < 0) 203 goto ecreate; 204 break; 205 case NAPPEND: 206 fname = redir->nfile.expfname; 207 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) 208 goto ecreate; 209 break; 210 case NTOFD: 211 case NFROMFD: 212 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */ 213 if (memory[redir->ndup.dupfd]) 214 memory[fd] = 1; 215 else 216 copyfd(redir->ndup.dupfd, fd, 1); 217 } 218 INTON; 219 return; 220 case NHERE: 221 case NXHERE: 222 f = openhere(redir); 223 break; 224 default: 225 abort(); 226 } 227 228 if (f != fd) { 229 copyfd(f, fd, 1); 230 close(f); 231 } 232 INTON; 233 return; 234 ecreate: 235 exerrno = 1; 236 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 237 eopen: 238 exerrno = 1; 239 error("cannot open %s: %s", fname, errmsg(errno, E_OPEN)); 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(const union node *redir) 251 { 252 int pip[2]; 253 int len = 0; 254 255 if (pipe(pip) < 0) 256 error("Pipe call failed"); 257 if (redir->type == NHERE) { 258 len = strlen(redir->nhere.doc->narg.text); 259 if (len <= PIPESIZE) { 260 xwrite(pip[1], redir->nhere.doc->narg.text, len); 261 goto out; 262 } 263 } 264 if (forkshell(NULL, NULL, FORK_NOJOB) == 0) { 265 close(pip[0]); 266 signal(SIGINT, SIG_IGN); 267 signal(SIGQUIT, SIG_IGN); 268 signal(SIGHUP, SIG_IGN); 269 #ifdef SIGTSTP 270 signal(SIGTSTP, SIG_IGN); 271 #endif 272 signal(SIGPIPE, SIG_DFL); 273 if (redir->type == NHERE) 274 xwrite(pip[1], redir->nhere.doc->narg.text, len); 275 else 276 expandhere(redir->nhere.doc, pip[1]); 277 _exit(0); 278 } 279 out: 280 close(pip[1]); 281 return pip[0]; 282 } 283 284 285 286 /* 287 * Undo the effects of the last redirection. 288 */ 289 290 void 291 popredir(void) 292 { 293 struct redirtab *rp = redirlist; 294 int i; 295 296 for (i = 0 ; i < 10 ; i++) { 297 if (rp->renamed[i] != EMPTY) { 298 if (i == 0) 299 fd0_redirected--; 300 close(i); 301 if (rp->renamed[i] >= 0) { 302 copyfd(rp->renamed[i], i, 1); 303 close(rp->renamed[i]); 304 } 305 } 306 } 307 INTOFF; 308 redirlist = rp->next; 309 ckfree(rp); 310 INTON; 311 } 312 313 /* 314 * Undo all redirections. Called on error or interrupt. 315 */ 316 317 #ifdef mkinit 318 319 INCLUDE "redir.h" 320 321 RESET { 322 while (redirlist) 323 popredir(); 324 } 325 326 SHELLPROC { 327 clearredir(0); 328 } 329 330 #endif 331 332 /* Return true if fd 0 has already been redirected at least once. */ 333 int 334 fd0_redirected_p (void) { 335 return fd0_redirected != 0; 336 } 337 338 /* 339 * Discard all saved file descriptors. 340 */ 341 342 void 343 clearredir(int vforked) 344 { 345 struct redirtab *rp; 346 int i; 347 348 for (rp = redirlist ; rp ; rp = rp->next) { 349 for (i = 0 ; i < 10 ; i++) { 350 if (rp->renamed[i] >= 0) { 351 close(rp->renamed[i]); 352 } 353 if (!vforked) 354 rp->renamed[i] = EMPTY; 355 } 356 } 357 } 358 359 360 361 /* 362 * Copy a file descriptor to be >= to. Returns -1 363 * if the source file descriptor is closed, EMPTY if there are no unused 364 * file descriptors left. 365 */ 366 367 int 368 copyfd(int from, int to, int equal) 369 { 370 int newfd; 371 372 if (equal) 373 newfd = dup2(from, to); 374 else 375 newfd = fcntl(from, F_DUPFD, to); 376 if (newfd < 0) { 377 if (errno == EMFILE) 378 return EMPTY; 379 else 380 error("%d: %s", from, strerror(errno)); 381 } 382 return newfd; 383 } 384