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 * 4. 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 33 #ifndef lint 34 #if 0 35 static char sccsid[] = "@(#)redir.c 8.2 (Berkeley) 5/4/95"; 36 #endif 37 #endif /* not lint */ 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include <sys/types.h> 42 #include <sys/stat.h> 43 #include <signal.h> 44 #include <string.h> 45 #include <fcntl.h> 46 #include <errno.h> 47 #include <unistd.h> 48 #include <stdlib.h> 49 50 /* 51 * Code for dealing with input/output redirection. 52 */ 53 54 #include "shell.h" 55 #include "nodes.h" 56 #include "jobs.h" 57 #include "expand.h" 58 #include "redir.h" 59 #include "output.h" 60 #include "memalloc.h" 61 #include "error.h" 62 #include "options.h" 63 64 65 #define EMPTY -2 /* marks an unused slot in redirtab */ 66 #define CLOSED -1 /* fd was not open before redir */ 67 68 69 struct redirtab { 70 struct redirtab *next; 71 int renamed[10]; 72 int fd0_redirected; 73 }; 74 75 76 static 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 * We suppress interrupts so that we won't leave open file 97 * descriptors around. Because the signal handler remains 98 * installed and we do not use system call restart, interrupts 99 * will still abort blocking opens such as fifos (they will fail 100 * with EINTR). There is, however, a race condition if an interrupt 101 * arrives after INTOFF and before open blocks. 102 */ 103 104 void 105 redirect(union node *redir, int flags) 106 { 107 union node *n; 108 struct redirtab *sv = NULL; 109 int i; 110 int fd; 111 char memory[10]; /* file descriptors to write to memory */ 112 113 INTOFF; 114 for (i = 10 ; --i >= 0 ; ) 115 memory[i] = 0; 116 memory[1] = flags & REDIR_BACKQ; 117 if (flags & REDIR_PUSH) { 118 sv = ckmalloc(sizeof (struct redirtab)); 119 for (i = 0 ; i < 10 ; i++) 120 sv->renamed[i] = EMPTY; 121 sv->fd0_redirected = fd0_redirected; 122 sv->next = redirlist; 123 redirlist = sv; 124 } 125 for (n = redir ; n ; n = n->nfile.next) { 126 fd = n->nfile.fd; 127 if (fd == 0) 128 fd0_redirected = 1; 129 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) && 130 n->ndup.dupfd == fd) 131 continue; /* redirect from/to same file descriptor */ 132 133 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { 134 INTOFF; 135 if ((i = fcntl(fd, F_DUPFD_CLOEXEC, 10)) == -1) { 136 switch (errno) { 137 case EBADF: 138 i = CLOSED; 139 break; 140 default: 141 INTON; 142 error("%d: %s", fd, strerror(errno)); 143 break; 144 } 145 } 146 sv->renamed[fd] = i; 147 INTON; 148 } 149 openredirect(n, memory); 150 INTON; 151 INTOFF; 152 } 153 if (memory[1]) 154 out1 = &memout; 155 if (memory[2]) 156 out2 = &memout; 157 INTON; 158 } 159 160 161 static void 162 openredirect(union node *redir, char memory[10]) 163 { 164 struct stat sb; 165 int fd = redir->nfile.fd; 166 const char *fname; 167 int f; 168 int e; 169 170 memory[fd] = 0; 171 switch (redir->nfile.type) { 172 case NFROM: 173 fname = redir->nfile.expfname; 174 if ((f = open(fname, O_RDONLY)) < 0) 175 error("cannot open %s: %s", fname, strerror(errno)); 176 break; 177 case NFROMTO: 178 fname = redir->nfile.expfname; 179 if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0) 180 error("cannot create %s: %s", fname, strerror(errno)); 181 break; 182 case NTO: 183 if (Cflag) { 184 fname = redir->nfile.expfname; 185 if (stat(fname, &sb) == -1) { 186 if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0) 187 error("cannot create %s: %s", fname, strerror(errno)); 188 } else if (!S_ISREG(sb.st_mode)) { 189 if ((f = open(fname, O_WRONLY, 0666)) < 0) 190 error("cannot create %s: %s", fname, strerror(errno)); 191 if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) { 192 close(f); 193 error("cannot create %s: %s", fname, 194 strerror(EEXIST)); 195 } 196 } else 197 error("cannot create %s: %s", fname, 198 strerror(EEXIST)); 199 break; 200 } 201 /* FALLTHROUGH */ 202 case NCLOBBER: 203 fname = redir->nfile.expfname; 204 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 205 error("cannot create %s: %s", fname, strerror(errno)); 206 break; 207 case NAPPEND: 208 fname = redir->nfile.expfname; 209 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) 210 error("cannot create %s: %s", fname, strerror(errno)); 211 break; 212 case NTOFD: 213 case NFROMFD: 214 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */ 215 if (memory[redir->ndup.dupfd]) 216 memory[fd] = 1; 217 else { 218 if (dup2(redir->ndup.dupfd, fd) < 0) 219 error("%d: %s", redir->ndup.dupfd, 220 strerror(errno)); 221 } 222 } else { 223 close(fd); 224 } 225 return; 226 case NHERE: 227 case NXHERE: 228 f = openhere(redir); 229 break; 230 default: 231 abort(); 232 } 233 if (f != fd) { 234 if (dup2(f, fd) == -1) { 235 e = errno; 236 close(f); 237 error("%d: %s", fd, strerror(e)); 238 } 239 close(f); 240 } 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 const char *p; 254 int pip[2]; 255 size_t len = 0; 256 int flags; 257 ssize_t written = 0; 258 259 if (pipe(pip) < 0) 260 error("Pipe call failed: %s", strerror(errno)); 261 262 if (redir->type == NXHERE) 263 p = redir->nhere.expdoc; 264 else 265 p = redir->nhere.doc->narg.text; 266 len = strlen(p); 267 if (len == 0) 268 goto out; 269 flags = fcntl(pip[1], F_GETFL, 0); 270 if (flags != -1 && fcntl(pip[1], F_SETFL, flags | O_NONBLOCK) != -1) { 271 written = write(pip[1], p, len); 272 if (written < 0) 273 written = 0; 274 if ((size_t)written == len) 275 goto out; 276 fcntl(pip[1], F_SETFL, flags); 277 } 278 279 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) { 280 close(pip[0]); 281 signal(SIGINT, SIG_IGN); 282 signal(SIGQUIT, SIG_IGN); 283 signal(SIGHUP, SIG_IGN); 284 signal(SIGTSTP, SIG_IGN); 285 signal(SIGPIPE, SIG_DFL); 286 xwrite(pip[1], p + written, len - written); 287 _exit(0); 288 } 289 out: 290 close(pip[1]); 291 return pip[0]; 292 } 293 294 295 296 /* 297 * Undo the effects of the last redirection. 298 */ 299 300 void 301 popredir(void) 302 { 303 struct redirtab *rp = redirlist; 304 int i; 305 306 for (i = 0 ; i < 10 ; i++) { 307 if (rp->renamed[i] != EMPTY) { 308 if (rp->renamed[i] >= 0) { 309 dup2(rp->renamed[i], i); 310 close(rp->renamed[i]); 311 } else { 312 close(i); 313 } 314 } 315 } 316 INTOFF; 317 fd0_redirected = rp->fd0_redirected; 318 redirlist = rp->next; 319 ckfree(rp); 320 INTON; 321 } 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