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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #ifndef lint 38 static char sccsid[] = "@(#)redir.c 8.1 (Berkeley) 5/31/93"; 39 #endif /* not lint */ 40 41 /* 42 * Code for dealing with input/output redirection. 43 */ 44 45 #include "shell.h" 46 #include "nodes.h" 47 #include "jobs.h" 48 #include "expand.h" 49 #include "redir.h" 50 #include "output.h" 51 #include "memalloc.h" 52 #include "error.h" 53 #include <sys/types.h> 54 #include <signal.h> 55 #include <fcntl.h> 56 #include <errno.h> 57 #include <unistd.h> 58 59 60 #define EMPTY -2 /* marks an unused slot in redirtab */ 61 #define PIPESIZE 4096 /* amount of buffering in a pipe */ 62 63 64 MKINIT 65 struct redirtab { 66 struct redirtab *next; 67 short renamed[10]; 68 }; 69 70 71 MKINIT struct redirtab *redirlist; 72 73 /* 74 * We keep track of whether or not fd0 has been redirected. This is for 75 * background commands, where we want to redirect fd0 to /dev/null only 76 * if it hasn't already been redirected. 77 */ 78 int fd0_redirected = 0; 79 80 #ifdef __STDC__ 81 STATIC void openredirect(union node *, char *); 82 STATIC int openhere(union node *); 83 #else 84 STATIC void openredirect(); 85 STATIC int openhere(); 86 #endif 87 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(redir, flags) 100 union node *redir; 101 int flags; 102 { 103 union node *n; 104 struct redirtab *sv; 105 int i; 106 int fd; 107 char memory[10]; /* file descriptors to write to memory */ 108 109 for (i = 10 ; --i >= 0 ; ) 110 memory[i] = 0; 111 memory[1] = flags & REDIR_BACKQ; 112 if (flags & REDIR_PUSH) { 113 sv = ckmalloc(sizeof (struct redirtab)); 114 for (i = 0 ; i < 10 ; i++) 115 sv->renamed[i] = EMPTY; 116 sv->next = redirlist; 117 redirlist = sv; 118 } 119 for (n = redir ; n ; n = n->nfile.next) { 120 fd = n->nfile.fd; 121 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { 122 INTOFF; 123 if ((i = copyfd(fd, 10)) != EMPTY) { 124 sv->renamed[fd] = i; 125 close(fd); 126 } 127 INTON; 128 if (i == EMPTY) 129 error("Out of file descriptors"); 130 } else { 131 close(fd); 132 } 133 if (fd == 0) 134 fd0_redirected++; 135 openredirect(n, memory); 136 } 137 if (memory[1]) 138 out1 = &memout; 139 if (memory[2]) 140 out2 = &memout; 141 } 142 143 144 STATIC void 145 openredirect(redir, memory) 146 union node *redir; 147 char memory[10]; 148 { 149 int fd = redir->nfile.fd; 150 char *fname; 151 int f; 152 153 /* 154 * We suppress interrupts so that we won't leave open file 155 * descriptors around. This may not be such a good idea because 156 * an open of a device or a fifo can block indefinitely. 157 */ 158 INTOFF; 159 memory[fd] = 0; 160 switch (redir->nfile.type) { 161 case NFROM: 162 fname = redir->nfile.expfname; 163 if ((f = open(fname, O_RDONLY)) < 0) 164 error("cannot open %s: %s", fname, errmsg(errno, E_OPEN)); 165 movefd: 166 if (f != fd) { 167 copyfd(f, fd); 168 close(f); 169 } 170 break; 171 case NTO: 172 fname = redir->nfile.expfname; 173 #ifdef O_CREAT 174 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 175 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 176 #else 177 if ((f = creat(fname, 0666)) < 0) 178 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 179 #endif 180 goto movefd; 181 case NAPPEND: 182 fname = redir->nfile.expfname; 183 #ifdef O_APPEND 184 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) 185 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 186 #else 187 if ((f = open(fname, O_WRONLY)) < 0 188 && (f = creat(fname, 0666)) < 0) 189 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 190 lseek(f, (off_t)0, 2); 191 #endif 192 goto movefd; 193 case NTOFD: 194 case NFROMFD: 195 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */ 196 if (memory[redir->ndup.dupfd]) 197 memory[fd] = 1; 198 else 199 copyfd(redir->ndup.dupfd, fd); 200 } 201 break; 202 case NHERE: 203 case NXHERE: 204 f = openhere(redir); 205 goto movefd; 206 default: 207 abort(); 208 } 209 INTON; 210 } 211 212 213 /* 214 * Handle here documents. Normally we fork off a process to write the 215 * data to a pipe. If the document is short, we can stuff the data in 216 * the pipe without forking. 217 */ 218 219 STATIC int 220 openhere(redir) 221 union node *redir; 222 { 223 int pip[2]; 224 int len; 225 226 if (pipe(pip) < 0) 227 error("Pipe call failed"); 228 if (redir->type == NHERE) { 229 len = strlen(redir->nhere.doc->narg.text); 230 if (len <= PIPESIZE) { 231 xwrite(pip[1], redir->nhere.doc->narg.text, len); 232 goto out; 233 } 234 } 235 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) { 236 close(pip[0]); 237 signal(SIGINT, SIG_IGN); 238 signal(SIGQUIT, SIG_IGN); 239 signal(SIGHUP, SIG_IGN); 240 #ifdef SIGTSTP 241 signal(SIGTSTP, SIG_IGN); 242 #endif 243 signal(SIGPIPE, SIG_DFL); 244 if (redir->type == NHERE) 245 xwrite(pip[1], redir->nhere.doc->narg.text, len); 246 else 247 expandhere(redir->nhere.doc, pip[1]); 248 _exit(0); 249 } 250 out: 251 close(pip[1]); 252 return pip[0]; 253 } 254 255 256 257 /* 258 * Undo the effects of the last redirection. 259 */ 260 261 void 262 popredir() { 263 register struct redirtab *rp = redirlist; 264 int i; 265 266 for (i = 0 ; i < 10 ; i++) { 267 if (rp->renamed[i] != EMPTY) { 268 if (i == 0) 269 fd0_redirected--; 270 close(i); 271 if (rp->renamed[i] >= 0) { 272 copyfd(rp->renamed[i], i); 273 close(rp->renamed[i]); 274 } 275 } 276 } 277 INTOFF; 278 redirlist = rp->next; 279 ckfree(rp); 280 INTON; 281 } 282 283 /* 284 * Undo all redirections. Called on error or interrupt. 285 */ 286 287 #ifdef mkinit 288 289 INCLUDE "redir.h" 290 291 RESET { 292 while (redirlist) 293 popredir(); 294 } 295 296 SHELLPROC { 297 clearredir(); 298 } 299 300 #endif 301 302 /* Return true if fd 0 has already been redirected at least once. */ 303 int 304 fd0_redirected_p () { 305 return fd0_redirected != 0; 306 } 307 308 /* 309 * Discard all saved file descriptors. 310 */ 311 312 void 313 clearredir() { 314 register struct redirtab *rp; 315 int i; 316 317 for (rp = redirlist ; rp ; rp = rp->next) { 318 for (i = 0 ; i < 10 ; i++) { 319 if (rp->renamed[i] >= 0) { 320 close(rp->renamed[i]); 321 } 322 rp->renamed[i] = EMPTY; 323 } 324 } 325 } 326 327 328 329 /* 330 * Copy a file descriptor to be >= to. Returns -1 331 * if the source file descriptor is closed, EMPTY if there are no unused 332 * file descriptors left. 333 */ 334 335 int 336 copyfd(from, to) { 337 int newfd; 338 339 newfd = fcntl(from, F_DUPFD, to); 340 if (newfd < 0 && errno == EMFILE) 341 return EMPTY; 342 return newfd; 343 } 344