redir.c revision 3044
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 * $Id$ 37 */ 38 39#ifndef lint 40static char sccsid[] = "@(#)redir.c 8.1 (Berkeley) 5/31/93"; 41#endif /* not lint */ 42 43/* 44 * Code for dealing with input/output redirection. 45 */ 46 47#include "shell.h" 48#include "nodes.h" 49#include "jobs.h" 50#include "expand.h" 51#include "redir.h" 52#include "output.h" 53#include "memalloc.h" 54#include "error.h" 55#include <sys/types.h> 56#include <signal.h> 57#include <fcntl.h> 58#include <errno.h> 59#include <unistd.h> 60 61 62#define EMPTY -2 /* marks an unused slot in redirtab */ 63#define PIPESIZE 4096 /* amount of buffering in a pipe */ 64 65 66MKINIT 67struct redirtab { 68 struct redirtab *next; 69 short renamed[10]; 70}; 71 72 73MKINIT struct redirtab *redirlist; 74 75/* 76 * We keep track of whether or not fd0 has been redirected. This is for 77 * background commands, where we want to redirect fd0 to /dev/null only 78 * if it hasn't already been redirected. 79*/ 80int fd0_redirected = 0; 81 82#ifdef __STDC__ 83STATIC void openredirect(union node *, char *); 84STATIC int openhere(union node *); 85#else 86STATIC void openredirect(); 87STATIC int openhere(); 88#endif 89 90 91 92/* 93 * Process a list of redirection commands. If the REDIR_PUSH flag is set, 94 * old file descriptors are stashed away so that the redirection can be 95 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the 96 * standard output, and the standard error if it becomes a duplicate of 97 * stdout, is saved in memory. 98 */ 99 100void 101redirect(redir, flags) 102 union node *redir; 103 int flags; 104 { 105 union node *n; 106 struct redirtab *sv; 107 int i; 108 int fd; 109 char memory[10]; /* file descriptors to write to memory */ 110 111 for (i = 10 ; --i >= 0 ; ) 112 memory[i] = 0; 113 memory[1] = flags & REDIR_BACKQ; 114 if (flags & REDIR_PUSH) { 115 sv = ckmalloc(sizeof (struct redirtab)); 116 for (i = 0 ; i < 10 ; i++) 117 sv->renamed[i] = EMPTY; 118 sv->next = redirlist; 119 redirlist = sv; 120 } 121 for (n = redir ; n ; n = n->nfile.next) { 122 fd = n->nfile.fd; 123 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { 124 INTOFF; 125 if ((i = copyfd(fd, 10)) != EMPTY) { 126 sv->renamed[fd] = i; 127 close(fd); 128 } 129 INTON; 130 if (i == EMPTY) 131 error("Out of file descriptors"); 132 } else { 133 close(fd); 134 } 135 if (fd == 0) 136 fd0_redirected++; 137 openredirect(n, memory); 138 } 139 if (memory[1]) 140 out1 = &memout; 141 if (memory[2]) 142 out2 = &memout; 143} 144 145 146STATIC void 147openredirect(redir, memory) 148 union node *redir; 149 char memory[10]; 150 { 151 int fd = redir->nfile.fd; 152 char *fname; 153 int f; 154 155 /* 156 * We suppress interrupts so that we won't leave open file 157 * descriptors around. This may not be such a good idea because 158 * an open of a device or a fifo can block indefinitely. 159 */ 160 INTOFF; 161 memory[fd] = 0; 162 switch (redir->nfile.type) { 163 case NFROM: 164 fname = redir->nfile.expfname; 165 if ((f = open(fname, O_RDONLY)) < 0) 166 error("cannot open %s: %s", fname, errmsg(errno, E_OPEN)); 167movefd: 168 if (f != fd) { 169 copyfd(f, fd); 170 close(f); 171 } 172 break; 173 case NTO: 174 fname = redir->nfile.expfname; 175#ifdef O_CREAT 176 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) 177 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 178#else 179 if ((f = creat(fname, 0666)) < 0) 180 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 181#endif 182 goto movefd; 183 case NAPPEND: 184 fname = redir->nfile.expfname; 185#ifdef O_APPEND 186 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) 187 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 188#else 189 if ((f = open(fname, O_WRONLY)) < 0 190 && (f = creat(fname, 0666)) < 0) 191 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT)); 192 lseek(f, (off_t)0, 2); 193#endif 194 goto movefd; 195 case NTOFD: 196 case NFROMFD: 197 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */ 198 if (memory[redir->ndup.dupfd]) 199 memory[fd] = 1; 200 else 201 copyfd(redir->ndup.dupfd, fd); 202 } 203 break; 204 case NHERE: 205 case NXHERE: 206 f = openhere(redir); 207 goto movefd; 208 default: 209 abort(); 210 } 211 INTON; 212} 213 214 215/* 216 * Handle here documents. Normally we fork off a process to write the 217 * data to a pipe. If the document is short, we can stuff the data in 218 * the pipe without forking. 219 */ 220 221STATIC int 222openhere(redir) 223 union node *redir; 224 { 225 int pip[2]; 226 int len; 227 228 if (pipe(pip) < 0) 229 error("Pipe call failed"); 230 if (redir->type == NHERE) { 231 len = strlen(redir->nhere.doc->narg.text); 232 if (len <= PIPESIZE) { 233 xwrite(pip[1], redir->nhere.doc->narg.text, len); 234 goto out; 235 } 236 } 237 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) { 238 close(pip[0]); 239 signal(SIGINT, SIG_IGN); 240 signal(SIGQUIT, SIG_IGN); 241 signal(SIGHUP, SIG_IGN); 242#ifdef SIGTSTP 243 signal(SIGTSTP, SIG_IGN); 244#endif 245 signal(SIGPIPE, SIG_DFL); 246 if (redir->type == NHERE) 247 xwrite(pip[1], redir->nhere.doc->narg.text, len); 248 else 249 expandhere(redir->nhere.doc, pip[1]); 250 _exit(0); 251 } 252out: 253 close(pip[1]); 254 return pip[0]; 255} 256 257 258 259/* 260 * Undo the effects of the last redirection. 261 */ 262 263void 264popredir() { 265 register struct redirtab *rp = redirlist; 266 int i; 267 268 for (i = 0 ; i < 10 ; i++) { 269 if (rp->renamed[i] != EMPTY) { 270 if (i == 0) 271 fd0_redirected--; 272 close(i); 273 if (rp->renamed[i] >= 0) { 274 copyfd(rp->renamed[i], i); 275 close(rp->renamed[i]); 276 } 277 } 278 } 279 INTOFF; 280 redirlist = rp->next; 281 ckfree(rp); 282 INTON; 283} 284 285/* 286 * Undo all redirections. Called on error or interrupt. 287 */ 288 289#ifdef mkinit 290 291INCLUDE "redir.h" 292 293RESET { 294 while (redirlist) 295 popredir(); 296} 297 298SHELLPROC { 299 clearredir(); 300} 301 302#endif 303 304/* Return true if fd 0 has already been redirected at least once. */ 305int 306fd0_redirected_p () { 307 return fd0_redirected != 0; 308} 309 310/* 311 * Discard all saved file descriptors. 312 */ 313 314void 315clearredir() { 316 register struct redirtab *rp; 317 int i; 318 319 for (rp = redirlist ; rp ; rp = rp->next) { 320 for (i = 0 ; i < 10 ; i++) { 321 if (rp->renamed[i] >= 0) { 322 close(rp->renamed[i]); 323 } 324 rp->renamed[i] = EMPTY; 325 } 326 } 327} 328 329 330 331/* 332 * Copy a file descriptor to be >= to. Returns -1 333 * if the source file descriptor is closed, EMPTY if there are no unused 334 * file descriptors left. 335 */ 336 337int 338copyfd(from, to) { 339 int newfd; 340 341 newfd = fcntl(from, F_DUPFD, to); 342 if (newfd < 0 && errno == EMFILE) 343 return EMPTY; 344 return newfd; 345} 346