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 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 int try; 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 try = 0; 120 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) && 121 n->ndup.dupfd == fd) 122 continue; /* redirect from/to same file descriptor */ 123 124 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { 125 INTOFF; 126 again: 127 if ((i = fcntl(fd, F_DUPFD, 10)) == -1) { 128 switch (errno) { 129 case EBADF: 130 if (!try) { 131 openredirect(n, memory); 132 try++; 133 goto again; 134 } 135 /* FALLTHROUGH*/ 136 default: 137 INTON; 138 error("%d: %s", fd, strerror(errno)); 139 break; 140 } 141 } 142 if (!try) { 143 sv->renamed[fd] = i; 144 } 145 INTON; 146 } 147 if (fd == 0) 148 fd0_redirected++; 149 if (!try) 150 openredirect(n, memory); 151 } 152 if (memory[1]) 153 out1 = &memout; 154 if (memory[2]) 155 out2 = &memout; 156 } 157 158 159 STATIC void 160 openredirect(union node *redir, char memory[10]) 161 { 162 struct stat sb; 163 int fd = redir->nfile.fd; 164 char *fname; 165 int f; 166 167 /* 168 * We suppress interrupts so that we won't leave open file 169 * descriptors around. This may not be such a good idea because 170 * an open of a device or a fifo can block indefinitely. 171 */ 172 INTOFF; 173 memory[fd] = 0; 174 switch (redir->nfile.type) { 175 case NFROM: 176 fname = redir->nfile.expfname; 177 if ((f = open(fname, O_RDONLY)) < 0) 178 error("cannot open %s: %s", fname, strerror(errno)); 179 movefd: 180 if (f != fd) { 181 dup2(f, fd); 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 fname = redir->nfile.expfname; 192 if (Cflag && stat(fname, &sb) != -1 && S_ISREG(sb.st_mode)) 193 error("cannot create %s: %s", fname, 194 strerror(EEXIST)); 195 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 196 error("cannot create %s: %s", fname, strerror(errno)); 197 goto movefd; 198 case NCLOBBER: 199 fname = redir->nfile.expfname; 200 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 201 error("cannot create %s: %s", fname, strerror(errno)); 202 goto movefd; 203 case NAPPEND: 204 fname = redir->nfile.expfname; 205 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) 206 error("cannot create %s: %s", fname, strerror(errno)); 207 goto movefd; 208 case NTOFD: 209 case NFROMFD: 210 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */ 211 if (memory[redir->ndup.dupfd]) 212 memory[fd] = 1; 213 else 214 dup2(redir->ndup.dupfd, fd); 215 } else { 216 close(fd); 217 } 218 break; 219 case NHERE: 220 case NXHERE: 221 f = openhere(redir); 222 goto movefd; 223 default: 224 abort(); 225 } 226 INTON; 227 } 228 229 230 /* 231 * Handle here documents. Normally we fork off a process to write the 232 * data to a pipe. If the document is short, we can stuff the data in 233 * the pipe without forking. 234 */ 235 236 STATIC int 237 openhere(union node *redir) 238 { 239 int pip[2]; 240 int len = 0; 241 242 if (pipe(pip) < 0) 243 error("Pipe call failed: %s", strerror(errno)); 244 if (redir->type == NHERE) { 245 len = strlen(redir->nhere.doc->narg.text); 246 if (len <= PIPESIZE) { 247 xwrite(pip[1], redir->nhere.doc->narg.text, len); 248 goto out; 249 } 250 } 251 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) { 252 close(pip[0]); 253 signal(SIGINT, SIG_IGN); 254 signal(SIGQUIT, SIG_IGN); 255 signal(SIGHUP, SIG_IGN); 256 signal(SIGTSTP, SIG_IGN); 257 signal(SIGPIPE, SIG_DFL); 258 if (redir->type == NHERE) 259 xwrite(pip[1], redir->nhere.doc->narg.text, len); 260 else 261 expandhere(redir->nhere.doc, pip[1]); 262 _exit(0); 263 } 264 out: 265 close(pip[1]); 266 return pip[0]; 267 } 268 269 270 271 /* 272 * Undo the effects of the last redirection. 273 */ 274 275 void 276 popredir(void) 277 { 278 struct redirtab *rp = redirlist; 279 int i; 280 281 for (i = 0 ; i < 10 ; i++) { 282 if (rp->renamed[i] != EMPTY) { 283 if (i == 0) 284 fd0_redirected--; 285 if (rp->renamed[i] >= 0) { 286 dup2(rp->renamed[i], i); 287 close(rp->renamed[i]); 288 } else { 289 close(i); 290 } 291 } 292 } 293 INTOFF; 294 redirlist = rp->next; 295 ckfree(rp); 296 INTON; 297 } 298 299 /* 300 * Undo all redirections. Called on error or interrupt. 301 */ 302 303 #ifdef mkinit 304 305 INCLUDE "redir.h" 306 307 RESET { 308 while (redirlist) 309 popredir(); 310 } 311 312 SHELLPROC { 313 clearredir(); 314 } 315 316 #endif 317 318 /* Return true if fd 0 has already been redirected at least once. */ 319 int 320 fd0_redirected_p(void) 321 { 322 return fd0_redirected != 0; 323 } 324 325 /* 326 * Discard all saved file descriptors. 327 */ 328 329 void 330 clearredir(void) 331 { 332 struct redirtab *rp; 333 int i; 334 335 for (rp = redirlist ; rp ; rp = rp->next) { 336 for (i = 0 ; i < 10 ; i++) { 337 if (rp->renamed[i] >= 0) { 338 close(rp->renamed[i]); 339 } 340 rp->renamed[i] = EMPTY; 341 } 342 } 343 } 344