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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)redir.c 8.2 (Berkeley) 5/4/95 33 * $FreeBSD: head/bin/sh/redir.c 246288 2013-02-03 15:54:57Z jilles $ 34 */ 35 36 #include <sys/types.h> 37 #include <sys/stat.h> 38 #include <signal.h> 39 #include <string.h> 40 #include <fcntl.h> 41 #include <errno.h> 42 #include <unistd.h> 43 #include <stdlib.h> 44 45 /* 46 * Code for dealing with input/output redirection. 47 */ 48 49 #include "shell.h" 50 #include "nodes.h" 51 #include "jobs.h" 52 #include "expand.h" 53 #include "redir.h" 54 #include "output.h" 55 #include "memalloc.h" 56 #include "error.h" 57 #include "options.h" 58 59 60 #define EMPTY -2 /* marks an unused slot in redirtab */ 61 #define CLOSED -1 /* fd was not open before redir */ 62 #define PIPESIZE 4096 /* amount of buffering in a pipe */ 63 64 65 MKINIT 66 struct redirtab { 67 struct redirtab *next; 68 int renamed[10]; 69 }; 70 71 72 MKINIT struct redirtab *redirlist; 73 74 /* 75 * We keep track of whether or not fd0 has been redirected. This is for 76 * background commands, where we want to redirect fd0 to /dev/null only 77 * if it hasn't already been redirected. 78 */ 79 static int fd0_redirected = 0; 80 81 static void openredirect(union node *, char[10 ]); 82 static int openhere(union node *); 83 84 85 /* 86 * Process a list of redirection commands. If the REDIR_PUSH flag is set, 87 * old file descriptors are stashed away so that the redirection can be 88 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the 89 * standard output, and the standard error if it becomes a duplicate of 90 * stdout, is saved in memory. 91 */ 92 93 void 94 redirect(union node *redir, int flags) 95 { 96 union node *n; 97 struct redirtab *sv = NULL; 98 int i; 99 int fd; 100 char memory[10]; /* file descriptors to write to memory */ 101 102 for (i = 10 ; --i >= 0 ; ) 103 memory[i] = 0; 104 memory[1] = flags & REDIR_BACKQ; 105 if (flags & REDIR_PUSH) { 106 sv = ckmalloc(sizeof (struct redirtab)); 107 for (i = 0 ; i < 10 ; i++) 108 sv->renamed[i] = EMPTY; 109 sv->next = redirlist; 110 redirlist = sv; 111 } 112 for (n = redir ; n ; n = n->nfile.next) { 113 fd = n->nfile.fd; 114 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) && 115 n->ndup.dupfd == fd) 116 continue; /* redirect from/to same file descriptor */ 117 118 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { 119 INTOFF; 120 if ((i = fcntl(fd, F_DUPFD, 10)) == -1) { 121 switch (errno) { 122 case EBADF: 123 i = CLOSED; 124 break; 125 default: 126 INTON; 127 error("%d: %s", fd, strerror(errno)); 128 break; 129 } 130 } else 131 (void)fcntl(i, F_SETFD, FD_CLOEXEC); 132 sv->renamed[fd] = i; 133 INTON; 134 } 135 if (fd == 0) 136 fd0_redirected++; 137 openredirect(n, memory); 138 } 139 if (memory[1]) 140 out1 = &memout; 141 if (memory[2]) 142 out2 = &memout; 143 } 144 145 146 static void 147 openredirect(union node *redir, char memory[10]) 148 { 149 struct stat sb; 150 int fd = redir->nfile.fd; 151 char *fname; 152 int f = 0; 153 int e; 154 155 /* 156 * We suppress interrupts so that we won't leave open file 157 * descriptors around. Because the signal handler remains 158 * installed and we do not use system call restart, interrupts 159 * will still abort blocking opens such as fifos (they will fail 160 * with EINTR). There is, however, a race condition if an interrupt 161 * arrives after INTOFF and before open blocks. 162 */ 163 INTOFF; 164 memory[fd] = 0; 165 switch (redir->nfile.type) { 166 case NFROM: 167 fname = redir->nfile.expfname; 168 if ((f = open(fname, O_RDONLY)) < 0) 169 error("cannot open %s: %s", fname, strerror(errno)); 170 movefd: 171 if (f != fd) { 172 if (dup2(f, fd) == -1) { 173 e = errno; 174 close(f); 175 error("%d: %s", fd, strerror(e)); 176 } 177 close(f); 178 } 179 break; 180 case NFROMTO: 181 fname = redir->nfile.expfname; 182 if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0) 183 error("cannot create %s: %s", fname, strerror(errno)); 184 goto movefd; 185 case NTO: 186 if (Cflag) { 187 fname = redir->nfile.expfname; 188 if (stat(fname, &sb) == -1) { 189 if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0) 190 error("cannot create %s: %s", fname, strerror(errno)); 191 } else if (!S_ISREG(sb.st_mode)) { 192 if ((f = open(fname, O_WRONLY, 0666)) < 0) 193 error("cannot create %s: %s", fname, strerror(errno)); 194 if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) { 195 close(f); 196 error("cannot create %s: %s", fname, 197 strerror(EEXIST)); 198 } 199 } else 200 error("cannot create %s: %s", fname, 201 strerror(EEXIST)); 202 goto movefd; 203 } 204 /* FALLTHROUGH */ 205 case NCLOBBER: 206 fname = redir->nfile.expfname; 207 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 208 error("cannot create %s: %s", fname, strerror(errno)); 209 goto movefd; 210 case NAPPEND: 211 fname = redir->nfile.expfname; 212 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) 213 error("cannot create %s: %s", fname, strerror(errno)); 214 goto movefd; 215 case NTOFD: 216 case NFROMFD: 217 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */ 218 if (memory[redir->ndup.dupfd]) 219 memory[fd] = 1; 220 else { 221 if (dup2(redir->ndup.dupfd, fd) < 0) 222 error("%d: %s", redir->ndup.dupfd, 223 strerror(errno)); 224 } 225 } else { 226 close(fd); 227 } 228 break; 229 case NHERE: 230 case NXHERE: 231 f = openhere(redir); 232 goto movefd; 233 default: 234 abort(); 235 } 236 INTON; 237 } 238 239 240 /* 241 * Handle here documents. Normally we fork off a process to write the 242 * data to a pipe. If the document is short, we can stuff the data in 243 * the pipe without forking. 244 */ 245 246 static int 247 openhere(union node *redir) 248 { 249 char *p; 250 int pip[2]; 251 int len = 0; 252 253 if (pipe(pip) < 0) 254 error("Pipe call failed: %s", strerror(errno)); 255 256 if (redir->type == NXHERE) 257 p = redir->nhere.expdoc; 258 else 259 p = redir->nhere.doc->narg.text; 260 len = strlen(p); 261 if (len <= PIPESIZE) { 262 xwrite(pip[1], p, len); 263 goto out; 264 } 265 266 if (forkshell(NULL, NULL, FORK_NOJOB) == 0) { 267 close(pip[0]); 268 signal(SIGINT, SIG_IGN); 269 signal(SIGQUIT, SIG_IGN); 270 signal(SIGHUP, SIG_IGN); 271 signal(SIGTSTP, SIG_IGN); 272 signal(SIGPIPE, SIG_DFL); 273 xwrite(pip[1], p, len); 274 _exit(0); 275 } 276 out: 277 close(pip[1]); 278 return pip[0]; 279 } 280 281 282 283 /* 284 * Undo the effects of the last redirection. 285 */ 286 287 void 288 popredir(void) 289 { 290 struct redirtab *rp = redirlist; 291 int i; 292 293 for (i = 0 ; i < 10 ; i++) { 294 if (rp->renamed[i] != EMPTY) { 295 if (i == 0) 296 fd0_redirected--; 297 if (rp->renamed[i] >= 0) { 298 dup2(rp->renamed[i], i); 299 close(rp->renamed[i]); 300 } else { 301 close(i); 302 } 303 } 304 } 305 INTOFF; 306 redirlist = rp->next; 307 ckfree(rp); 308 INTON; 309 } 310 311 /* 312 * Undo all redirections. Called on error or interrupt. 313 */ 314 315 #ifdef mkinit 316 317 INCLUDE "redir.h" 318 319 RESET { 320 while (redirlist) 321 popredir(); 322 } 323 324 #endif 325 326 /* Return true if fd 0 has already been redirected at least once. */ 327 int 328 fd0_redirected_p(void) 329 { 330 return fd0_redirected != 0; 331 } 332 333 /* 334 * Discard all saved file descriptors. 335 */ 336 337 void 338 clearredir(void) 339 { 340 struct redirtab *rp; 341 int i; 342 343 for (rp = redirlist ; rp ; rp = rp->next) { 344 for (i = 0 ; i < 10 ; i++) { 345 if (rp->renamed[i] >= 0) { 346 close(rp->renamed[i]); 347 } 348 rp->renamed[i] = EMPTY; 349 } 350 } 351 } 352