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 #define PIPESIZE 4096 /* amount of buffering in a pipe */ 68 69 70 MKINIT 71 struct redirtab { 72 struct redirtab *next; 73 int renamed[10]; 74 }; 75 76 77 MKINIT struct redirtab *redirlist; 78 79 /* 80 * We keep track of whether or not fd0 has been redirected. This is for 81 * background commands, where we want to redirect fd0 to /dev/null only 82 * if it hasn't already been redirected. 83 */ 84 static int fd0_redirected = 0; 85 86 static void openredirect(union node *, char[10 ]); 87 static int openhere(union node *); 88 89 90 /* 91 * Process a list of redirection commands. If the REDIR_PUSH flag is set, 92 * old file descriptors are stashed away so that the redirection can be 93 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the 94 * standard output, and the standard error if it becomes a duplicate of 95 * stdout, is saved in memory. 96 */ 97 98 void 99 redirect(union node *redir, int flags) 100 { 101 union node *n; 102 struct redirtab *sv = NULL; 103 int i; 104 int fd; 105 char memory[10]; /* file descriptors to write to memory */ 106 107 for (i = 10 ; --i >= 0 ; ) 108 memory[i] = 0; 109 memory[1] = flags & REDIR_BACKQ; 110 if (flags & REDIR_PUSH) { 111 sv = ckmalloc(sizeof (struct redirtab)); 112 for (i = 0 ; i < 10 ; i++) 113 sv->renamed[i] = EMPTY; 114 sv->next = redirlist; 115 redirlist = sv; 116 } 117 for (n = redir ; n ; n = n->nfile.next) { 118 fd = n->nfile.fd; 119 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) && 120 n->ndup.dupfd == fd) 121 continue; /* redirect from/to same file descriptor */ 122 123 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { 124 INTOFF; 125 if ((i = fcntl(fd, F_DUPFD, 10)) == -1) { 126 switch (errno) { 127 case EBADF: 128 i = CLOSED; 129 break; 130 default: 131 INTON; 132 error("%d: %s", fd, strerror(errno)); 133 break; 134 } 135 } else 136 (void)fcntl(i, F_SETFD, FD_CLOEXEC); 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; 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 dup2(f, fd); 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 int pip[2]; 250 int len = 0; 251 252 if (pipe(pip) < 0) 253 error("Pipe call failed: %s", strerror(errno)); 254 if (redir->type == NHERE) { 255 len = strlen(redir->nhere.doc->narg.text); 256 if (len <= PIPESIZE) { 257 xwrite(pip[1], redir->nhere.doc->narg.text, len); 258 goto out; 259 } 260 } 261 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) { 262 close(pip[0]); 263 signal(SIGINT, SIG_IGN); 264 signal(SIGQUIT, SIG_IGN); 265 signal(SIGHUP, SIG_IGN); 266 signal(SIGTSTP, SIG_IGN); 267 signal(SIGPIPE, SIG_DFL); 268 if (redir->type == NHERE) 269 xwrite(pip[1], redir->nhere.doc->narg.text, len); 270 else 271 expandhere(redir->nhere.doc, pip[1]); 272 _exit(0); 273 } 274 out: 275 close(pip[1]); 276 return pip[0]; 277 } 278 279 280 281 /* 282 * Undo the effects of the last redirection. 283 */ 284 285 void 286 popredir(void) 287 { 288 struct redirtab *rp = redirlist; 289 int i; 290 291 for (i = 0 ; i < 10 ; i++) { 292 if (rp->renamed[i] != EMPTY) { 293 if (i == 0) 294 fd0_redirected--; 295 if (rp->renamed[i] >= 0) { 296 dup2(rp->renamed[i], i); 297 close(rp->renamed[i]); 298 } else { 299 close(i); 300 } 301 } 302 } 303 INTOFF; 304 redirlist = rp->next; 305 ckfree(rp); 306 INTON; 307 } 308 309 /* 310 * Undo all redirections. Called on error or interrupt. 311 */ 312 313 #ifdef mkinit 314 315 INCLUDE "redir.h" 316 317 RESET { 318 while (redirlist) 319 popredir(); 320 } 321 322 SHELLPROC { 323 clearredir(); 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