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 * @(#)redir.c 8.2 (Berkeley) 5/4/95 37 * $FreeBSD: src/bin/sh/redir.c,v 1.34 2011/02/04 22:47:55 jilles Exp $ 38 */ 39 40 #include <sys/types.h> 41 #include <sys/stat.h> 42 #include <signal.h> 43 #include <string.h> 44 #include <fcntl.h> 45 #include <errno.h> 46 #include <unistd.h> 47 #include <stdlib.h> 48 49 /* 50 * Code for dealing with input/output redirection. 51 */ 52 53 #include "shell.h" 54 #include "nodes.h" 55 #include "jobs.h" 56 #include "expand.h" 57 #include "redir.h" 58 #include "output.h" 59 #include "memalloc.h" 60 #include "error.h" 61 #include "options.h" 62 63 64 #define EMPTY -2 /* marks an unused slot in redirtab */ 65 #define CLOSED -1 /* fd was not open before redir */ 66 #define PIPESIZE 4096 /* amount of buffering in a pipe */ 67 68 69 MKINIT 70 struct redirtab { 71 struct redirtab *next; 72 int 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 static int fd0_redirected = 0; 84 85 static void openredirect(union node *, char[10 ]); 86 static int openhere(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(union node *redir, int flags) 99 { 100 union node *n; 101 struct redirtab *sv = NULL; 102 int i; 103 int fd; 104 char memory[10]; /* file descriptors to write to memory */ 105 106 for (i = 10 ; --i >= 0 ; ) 107 memory[i] = 0; 108 memory[1] = flags & REDIR_BACKQ; 109 if (flags & REDIR_PUSH) { 110 sv = ckmalloc(sizeof (struct redirtab)); 111 for (i = 0 ; i < 10 ; i++) 112 sv->renamed[i] = EMPTY; 113 sv->next = redirlist; 114 redirlist = sv; 115 } 116 for (n = redir ; n ; n = n->nfile.next) { 117 fd = n->nfile.fd; 118 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) && 119 n->ndup.dupfd == fd) 120 continue; /* redirect from/to same file descriptor */ 121 122 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { 123 INTOFF; 124 if ((i = fcntl(fd, F_DUPFD, 10)) == -1) { 125 switch (errno) { 126 case EBADF: 127 i = CLOSED; 128 break; 129 default: 130 INTON; 131 error("%d: %s", fd, strerror(errno)); 132 break; 133 } 134 } else 135 (void)fcntl(i, F_SETFD, FD_CLOEXEC); 136 sv->renamed[fd] = i; 137 INTON; 138 } 139 if (fd == 0) 140 fd0_redirected++; 141 openredirect(n, memory); 142 } 143 if (memory[1]) 144 out1 = &memout; 145 if (memory[2]) 146 out2 = &memout; 147 } 148 149 150 static void 151 openredirect(union node *redir, char memory[10]) 152 { 153 struct stat sb; 154 int fd = redir->nfile.fd; 155 char *fname; 156 int f = 0; 157 int e; 158 159 /* 160 * We suppress interrupts so that we won't leave open file 161 * descriptors around. Because the signal handler remains 162 * installed and we do not use system call restart, interrupts 163 * will still abort blocking opens such as fifos (they will fail 164 * with EINTR). There is, however, a race condition if an interrupt 165 * arrives after INTOFF and before open blocks. 166 */ 167 INTOFF; 168 memory[fd] = 0; 169 switch (redir->nfile.type) { 170 case NFROM: 171 fname = redir->nfile.expfname; 172 if ((f = open(fname, O_RDONLY)) < 0) 173 error("cannot open %s: %s", fname, strerror(errno)); 174 movefd: 175 if (f != fd) { 176 if (dup2(f, fd) == -1) { 177 e = errno; 178 close(f); 179 error("%d: %s", fd, strerror(e)); 180 } 181 close(f); 182 } 183 break; 184 case NFROMTO: 185 fname = redir->nfile.expfname; 186 if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0) 187 error("cannot create %s: %s", fname, strerror(errno)); 188 goto movefd; 189 case NTO: 190 if (Cflag) { 191 fname = redir->nfile.expfname; 192 if (stat(fname, &sb) == -1) { 193 if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0) 194 error("cannot create %s: %s", fname, strerror(errno)); 195 } else if (!S_ISREG(sb.st_mode)) { 196 if ((f = open(fname, O_WRONLY, 0666)) < 0) 197 error("cannot create %s: %s", fname, strerror(errno)); 198 if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) { 199 close(f); 200 error("cannot create %s: %s", fname, 201 strerror(EEXIST)); 202 } 203 } else 204 error("cannot create %s: %s", fname, 205 strerror(EEXIST)); 206 goto movefd; 207 } 208 /* FALLTHROUGH */ 209 case NCLOBBER: 210 fname = redir->nfile.expfname; 211 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 212 error("cannot create %s: %s", fname, strerror(errno)); 213 goto movefd; 214 case NAPPEND: 215 fname = redir->nfile.expfname; 216 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) 217 error("cannot create %s: %s", fname, strerror(errno)); 218 goto movefd; 219 case NTOFD: 220 case NFROMFD: 221 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */ 222 if (memory[redir->ndup.dupfd]) 223 memory[fd] = 1; 224 else { 225 if (dup2(redir->ndup.dupfd, fd) < 0) 226 error("%d: %s", redir->ndup.dupfd, 227 strerror(errno)); 228 } 229 } else { 230 close(fd); 231 } 232 break; 233 case NHERE: 234 case NXHERE: 235 f = openhere(redir); 236 goto movefd; 237 default: 238 abort(); 239 } 240 INTON; 241 } 242 243 244 /* 245 * Handle here documents. Normally we fork off a process to write the 246 * data to a pipe. If the document is short, we can stuff the data in 247 * the pipe without forking. 248 */ 249 250 static int 251 openhere(union node *redir) 252 { 253 int pip[2]; 254 int len = 0; 255 256 if (pipe(pip) < 0) 257 error("Pipe call failed: %s", strerror(errno)); 258 if (redir->type == NHERE) { 259 len = strlen(redir->nhere.doc->narg.text); 260 if (len <= PIPESIZE) { 261 xwrite(pip[1], redir->nhere.doc->narg.text, len); 262 goto out; 263 } 264 } 265 if (forkshell(NULL, NULL, FORK_NOJOB) == 0) { 266 close(pip[0]); 267 signal(SIGINT, SIG_IGN); 268 signal(SIGQUIT, SIG_IGN); 269 signal(SIGHUP, SIG_IGN); 270 signal(SIGTSTP, SIG_IGN); 271 signal(SIGPIPE, SIG_DFL); 272 if (redir->type == NHERE) 273 xwrite(pip[1], redir->nhere.doc->narg.text, len); 274 else 275 expandhere(redir->nhere.doc, pip[1]); 276 _exit(0); 277 } 278 out: 279 close(pip[1]); 280 return pip[0]; 281 } 282 283 284 285 /* 286 * Undo the effects of the last redirection. 287 */ 288 289 void 290 popredir(void) 291 { 292 struct redirtab *rp = redirlist; 293 int i; 294 295 for (i = 0 ; i < 10 ; i++) { 296 if (rp->renamed[i] != EMPTY) { 297 if (i == 0) 298 fd0_redirected--; 299 if (rp->renamed[i] >= 0) { 300 dup2(rp->renamed[i], i); 301 close(rp->renamed[i]); 302 } else { 303 close(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 #endif 327 328 /* Return true if fd 0 has already been redirected at least once. */ 329 int 330 fd0_redirected_p(void) 331 { 332 return fd0_redirected != 0; 333 } 334 335 /* 336 * Discard all saved file descriptors. 337 */ 338 339 void 340 clearredir(void) 341 { 342 struct redirtab *rp; 343 int i; 344 345 for (rp = redirlist ; rp ; rp = rp->next) { 346 for (i = 0 ; i < 10 ; i++) { 347 if (rp->renamed[i] >= 0) { 348 close(rp->renamed[i]); 349 } 350 rp->renamed[i] = EMPTY; 351 } 352 } 353 } 354