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 253658 2013-07-25 19:48:15Z 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 63 64 struct redirtab { 65 struct redirtab *next; 66 int renamed[10]; 67 }; 68 69 70 static struct redirtab *redirlist; 71 72 /* 73 * We keep track of whether or not fd0 has been redirected. This is for 74 * background commands, where we want to redirect fd0 to /dev/null only 75 * if it hasn't already been redirected. 76 */ 77 static int fd0_redirected = 0; 78 79 static void openredirect(union node *, char[10 ]); 80 static int openhere(union node *); 81 82 83 /* 84 * Process a list of redirection commands. If the REDIR_PUSH flag is set, 85 * old file descriptors are stashed away so that the redirection can be 86 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the 87 * standard output, and the standard error if it becomes a duplicate of 88 * stdout, is saved in memory. 89 */ 90 91 void 92 redirect(union node *redir, int flags) 93 { 94 union node *n; 95 struct redirtab *sv = NULL; 96 int i; 97 int fd; 98 char memory[10]; /* file descriptors to write to memory */ 99 100 for (i = 10 ; --i >= 0 ; ) 101 memory[i] = 0; 102 memory[1] = flags & REDIR_BACKQ; 103 if (flags & REDIR_PUSH) { 104 sv = ckmalloc(sizeof (struct redirtab)); 105 for (i = 0 ; i < 10 ; i++) 106 sv->renamed[i] = EMPTY; 107 sv->next = redirlist; 108 redirlist = sv; 109 } 110 for (n = redir ; n ; n = n->nfile.next) { 111 fd = n->nfile.fd; 112 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) && 113 n->ndup.dupfd == fd) 114 continue; /* redirect from/to same file descriptor */ 115 116 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { 117 INTOFF; 118 #ifndef F_DUPFD_CLOEXEC 119 if ((i = fcntl(fd, F_DUPFD, 10)) == -1) { 120 #else 121 if ((i = fcntl(fd, F_DUPFD_CLOEXEC, 10)) == -1) { 122 #endif 123 switch (errno) { 124 case EBADF: 125 i = CLOSED; 126 break; 127 default: 128 INTON; 129 error("%d: %s", fd, strerror(errno)); 130 break; 131 } 132 } 133 #if !defined(O_CLOEXEC) || !defined(F_DUPFD_CLOEXEC) 134 else 135 fcntl(i, F_SETFD, FD_CLOEXEC); 136 #endif 137 sv->renamed[fd] = i; 138 INTON; 139 } 140 if (fd == 0) 141 fd0_redirected++; 142 openredirect(n, memory); 143 } 144 if (memory[1]) 145 out1 = &memout; 146 if (memory[2]) 147 out2 = &memout; 148 } 149 150 151 static void 152 openredirect(union node *redir, char memory[10]) 153 { 154 struct stat sb; 155 int fd = redir->nfile.fd; 156 char *fname; 157 int f = 0; 158 int e; 159 160 /* 161 * We suppress interrupts so that we won't leave open file 162 * descriptors around. Because the signal handler remains 163 * installed and we do not use system call restart, interrupts 164 * will still abort blocking opens such as fifos (they will fail 165 * with EINTR). There is, however, a race condition if an interrupt 166 * arrives after INTOFF and before open blocks. 167 */ 168 INTOFF; 169 memory[fd] = 0; 170 switch (redir->nfile.type) { 171 case NFROM: 172 fname = redir->nfile.expfname; 173 if ((f = open(fname, O_RDONLY)) < 0) 174 error("cannot open %s: %s", fname, strerror(errno)); 175 movefd: 176 if (f != fd) { 177 if (dup2(f, fd) == -1) { 178 e = errno; 179 close(f); 180 error("%d: %s", fd, strerror(e)); 181 } 182 close(f); 183 } 184 break; 185 case NFROMTO: 186 fname = redir->nfile.expfname; 187 if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0) 188 error("cannot create %s: %s", fname, strerror(errno)); 189 goto movefd; 190 case NTO: 191 if (Cflag) { 192 fname = redir->nfile.expfname; 193 if (stat(fname, &sb) == -1) { 194 if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0) 195 error("cannot create %s: %s", fname, strerror(errno)); 196 } else if (!S_ISREG(sb.st_mode)) { 197 if ((f = open(fname, O_WRONLY, 0666)) < 0) 198 error("cannot create %s: %s", fname, strerror(errno)); 199 if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) { 200 close(f); 201 error("cannot create %s: %s", fname, 202 strerror(EEXIST)); 203 } 204 } else 205 error("cannot create %s: %s", fname, 206 strerror(EEXIST)); 207 goto movefd; 208 } 209 /* FALLTHROUGH */ 210 case NCLOBBER: 211 fname = redir->nfile.expfname; 212 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 213 error("cannot create %s: %s", fname, strerror(errno)); 214 goto movefd; 215 case NAPPEND: 216 fname = redir->nfile.expfname; 217 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) 218 error("cannot create %s: %s", fname, strerror(errno)); 219 goto movefd; 220 case NTOFD: 221 case NFROMFD: 222 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */ 223 if (memory[redir->ndup.dupfd]) 224 memory[fd] = 1; 225 else { 226 if (dup2(redir->ndup.dupfd, fd) < 0) 227 error("%d: %s", redir->ndup.dupfd, 228 strerror(errno)); 229 } 230 } else { 231 close(fd); 232 } 233 break; 234 case NHERE: 235 case NXHERE: 236 f = openhere(redir); 237 goto movefd; 238 default: 239 abort(); 240 } 241 INTON; 242 } 243 244 245 /* 246 * Handle here documents. Normally we fork off a process to write the 247 * data to a pipe. If the document is short, we can stuff the data in 248 * the pipe without forking. 249 */ 250 251 static int 252 openhere(union node *redir) 253 { 254 char *p; 255 int pip[2]; 256 size_t len = 0; 257 int flags; 258 ssize_t written = 0; 259 260 if (pipe(pip) < 0) 261 error("Pipe call failed: %s", strerror(errno)); 262 263 if (redir->type == NXHERE) 264 p = redir->nhere.expdoc; 265 else 266 p = redir->nhere.doc->narg.text; 267 len = strlen(p); 268 if (len == 0) 269 goto out; 270 flags = fcntl(pip[1], F_GETFL, 0); 271 if (flags != -1 && fcntl(pip[1], F_SETFL, flags | O_NONBLOCK) != -1) { 272 written = write(pip[1], p, len); 273 if (written < 0) 274 written = 0; 275 if ((size_t)written == len) 276 goto out; 277 fcntl(pip[1], F_SETFL, flags); 278 } 279 280 if (forkshell(NULL, NULL, FORK_NOJOB) == 0) { 281 close(pip[0]); 282 signal(SIGINT, SIG_IGN); 283 signal(SIGQUIT, SIG_IGN); 284 signal(SIGHUP, SIG_IGN); 285 signal(SIGTSTP, SIG_IGN); 286 signal(SIGPIPE, SIG_DFL); 287 xwrite(pip[1], p + written, len - written); 288 _exit(0); 289 } 290 out: 291 close(pip[1]); 292 return pip[0]; 293 } 294 295 296 297 /* 298 * Undo the effects of the last redirection. 299 */ 300 301 void 302 popredir(void) 303 { 304 struct redirtab *rp = redirlist; 305 int i; 306 307 for (i = 0 ; i < 10 ; i++) { 308 if (rp->renamed[i] != EMPTY) { 309 if (i == 0) 310 fd0_redirected--; 311 if (rp->renamed[i] >= 0) { 312 dup2(rp->renamed[i], i); 313 close(rp->renamed[i]); 314 } else { 315 close(i); 316 } 317 } 318 } 319 INTOFF; 320 redirlist = rp->next; 321 ckfree(rp); 322 INTON; 323 } 324 325 /* 326 * Undo all redirections. Called on error or interrupt. 327 */ 328 329 void 330 resetredir(void) 331 { 332 while (redirlist) 333 popredir(); 334 } 335 336 337 /* Return true if fd 0 has already been redirected at least once. */ 338 int 339 fd0_redirected_p(void) 340 { 341 return fd0_redirected != 0; 342 } 343 344 /* 345 * Discard all saved file descriptors. 346 */ 347 348 void 349 clearredir(void) 350 { 351 struct redirtab *rp; 352 int i; 353 354 for (rp = redirlist ; rp ; rp = rp->next) { 355 for (i = 0 ; i < 10 ; i++) { 356 if (rp->renamed[i] >= 0) { 357 close(rp->renamed[i]); 358 } 359 rp->renamed[i] = EMPTY; 360 } 361 } 362 } 363