src/ash/redir.c

   1 /*      $NetBSD: redir.c,v 1.29 2004/07/08 03:57:33 christos Exp $      */
   2
   3 /*-
   4  * Copyright (c) 1991, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Kenneth Almquist.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #ifdef HAVE_SYS_CDEFS_H
  36 #include <sys/cdefs.h>
  37 #endif
  38 #ifndef lint
  39 #if 0
  40 static char sccsid[] = "@(#)redir.c     8.2 (Berkeley) 5/4/95";
  41 #else
  42 __RCSID("$NetBSD: redir.c,v 1.29 2004/07/08 03:57:33 christos Exp $");
  43 #endif
  44 #endif /* not lint */
  45
  46 #include <sys/types.h>
  47 #include <sys/param.h>  /* PIPE_BUF */
  48 #include <signal.h>
  49 #include <string.h>
  50 #include <fcntl.h>
  51 #include <errno.h>
  52 #include <unistd.h>
  53 #include <stdlib.h>
  54
  55 /*
  56  * Code for dealing with input/output redirection.
  57  */
  58
  59 #include "main.h"
  60 #include "shell.h"
  61 #include "nodes.h"
  62 #include "jobs.h"
  63 #include "options.h"
  64 #include "expand.h"
  65 #include "redir.h"
  66 #include "output.h"
  67 #include "memalloc.h"
  68 #include "error.h"
  69
  70
  71 #define EMPTY -2                /* marks an unused slot in redirtab */
  72 #ifndef PIPE_BUF
  73 # define PIPESIZE 4096          /* amount of buffering in a pipe */
  74 #else
  75 # define PIPESIZE PIPE_BUF
  76 #endif
  77
  78
  79 MKINIT
  80 struct redirtab {
  81         struct redirtab *next;
  82         short renamed[10];
  83 };
  84
  85
  86 MKINIT struct redirtab *redirlist;
  87
  88 /*
  89  * We keep track of whether or not fd0 has been redirected.  This is for
  90  * background commands, where we want to redirect fd0 to /dev/null only
  91  * if it hasn't already been redirected.
  92 */
  93 int fd0_redirected = 0;
  94
  95 STATIC void openredirect(union node *, char[10], int);
  96 STATIC int openhere(union node *);
  97
  98
  99 /*
 100  * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
 101  * old file descriptors are stashed away so that the redirection can be
 102  * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
 103  * standard output, and the standard error if it becomes a duplicate of
 104  * stdout, is saved in memory.
 105  */
 106
 107 void
 108 redirect(union node *redir, int flags)
 109 {
 110         union node *n;
 111         struct redirtab *sv = NULL;
 112         int i;
 113         int fd;
 114         int try;
 115         char memory[10];        /* file descriptors to write to memory */
 116
 117         for (i = 10 ; --i >= 0 ; )
 118                 memory[i] = 0;
 119         memory[1] = flags & REDIR_BACKQ;
 120         if (flags & REDIR_PUSH) {
 121                 /* We don't have to worry about REDIR_VFORK here, as
 122                  * flags & REDIR_PUSH is never true if REDIR_VFORK is set.
 123                  */
 124                 sv = ckmalloc(sizeof (struct redirtab));
 125                 for (i = 0 ; i < 10 ; i++)
 126                         sv->renamed[i] = EMPTY;
 127                 sv->next = redirlist;
 128                 redirlist = sv;
 129         }
 130         for (n = redir ; n ; n = n->nfile.next) {
 131                 fd = n->nfile.fd;
 132                 try = 0;
 133                 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
 134                     n->ndup.dupfd == fd)
 135                         continue; /* redirect from/to same file descriptor */
 136
 137                 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
 138                         INTOFF;
 139 again:
 140                         if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
 141                                 switch (errno) {
 142                                 case EBADF:
 143                                         if (!try) {
 144                                                 openredirect(n, memory, flags);
 145                                                 try++;
 146                                                 goto again;
 147                                         }
 148                                         /* FALLTHROUGH*/
 149                                 default:
 150                                         INTON;
 151                                         error("%d: %s", fd, strerror(errno));
 152                                         /* NOTREACHED */
 153                                 }
 154                         }
 155                         if (!try) {
 156                                 sv->renamed[fd] = i;
 157                                 close(fd);
 158                         }
 159                         INTON;
 160                 } else {
 161                         close(fd);
 162                 }
 163                 if (fd == 0)
 164                         fd0_redirected++;
 165                 if (!try)
 166                         openredirect(n, memory, flags);
 167         }
 168         if (memory[1])
 169                 out1 = &memout;
 170         if (memory[2])
 171                 out2 = &memout;
 172 }
 173
 174
 175 STATIC void
 176 openredirect(union node *redir, char memory[10], int flags)
 177 {
 178         int fd = redir->nfile.fd;
 179         char *fname;
 180         int f;
 181         int oflags = O_WRONLY|O_CREAT|O_TRUNC, eflags;
 182
 183         /*
 184          * We suppress interrupts so that we won't leave open file
 185          * descriptors around.  This may not be such a good idea because
 186          * an open of a device or a fifo can block indefinitely.
 187          */
 188         INTOFF;
 189         memory[fd] = 0;
 190         switch (redir->nfile.type) {
 191         case NFROM:
 192                 fname = redir->nfile.expfname;
 193                 if (flags & REDIR_VFORK)
 194                         eflags = O_NONBLOCK;
 195                 else
 196                         eflags = 0;
 197                 if ((f = open(fname, O_RDONLY|eflags)) < 0)
 198                         goto eopen;
 199                 if (eflags)
 200                         (void)fcntl(f, F_SETFL, fcntl(f, F_GETFL, 0) & ~eflags);
 201                 break;
 202         case NFROMTO:
 203                 fname = redir->nfile.expfname;
 204                 if ((f = open(fname, O_RDWR|O_CREAT|O_TRUNC, 0666)) < 0)
 205                         goto ecreate;
 206                 break;
 207         case NTO:
 208                 if (Cflag)
 209                         oflags |= O_EXCL;
 210                 /* FALLTHROUGH */
 211         case NCLOBBER:
 212                 fname = redir->nfile.expfname;
 213                 if ((f = open(fname, oflags, 0666)) < 0)
 214                         goto ecreate;
 215                 break;
 216         case NAPPEND:
 217                 fname = redir->nfile.expfname;
 218                 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
 219                         goto ecreate;
 220                 break;
 221         case NTOFD:
 222         case NFROMFD:
 223                 if (redir->ndup.dupfd >= 0) {   /* if not ">&-" */
 224                         if (memory[redir->ndup.dupfd])
 225                                 memory[fd] = 1;
 226                         else
 227                                 copyfd(redir->ndup.dupfd, fd);
 228                 }
 229                 INTON;
 230                 return;
 231         case NHERE:
 232         case NXHERE:
 233                 f = openhere(redir);
 234                 break;
 235         default:
 236                 abort();
 237         }
 238
 239         if (f != fd) {
 240                 copyfd(f, fd);
 241                 close(f);
 242         }
 243         INTON;
 244         return;
 245 ecreate:
 246         error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
 247 eopen:
 248         error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
 249 }
 250
 251
 252 /*
 253  * Handle here documents.  Normally we fork off a process to write the
 254  * data to a pipe.  If the document is short, we can stuff the data in
 255  * the pipe without forking.
 256  */
 257
 258 STATIC int
 259 openhere(union node *redir)
 260 {
 261         int pip[2];
 262         int len = 0;
 263
 264         if (pipe(pip) < 0)
 265                 error("Pipe call failed");
 266         if (redir->type == NHERE) {
 267                 len = strlen(redir->nhere.doc->narg.text);
 268                 if (len <= PIPESIZE) {
 269                         xwrite(pip[1], redir->nhere.doc->narg.text, len);
 270                         goto out;
 271                 }
 272         }
 273         if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
 274                 close(pip[0]);
 275                 signal(SIGINT, SIG_IGN);
 276                 signal(SIGQUIT, SIG_IGN);
 277                 signal(SIGHUP, SIG_IGN);
 278 #ifdef SIGTSTP
 279                 signal(SIGTSTP, SIG_IGN);
 280 #endif
 281                 signal(SIGPIPE, SIG_DFL);
 282                 if (redir->type == NHERE)
 283                         xwrite(pip[1], redir->nhere.doc->narg.text, len);
 284                 else
 285                         expandhere(redir->nhere.doc, pip[1]);
 286                 _exit(0);
 287         }
 288 out:
 289         close(pip[1]);
 290         return pip[0];
 291 }
 292
 293
 294
 295 /*
 296  * Undo the effects of the last redirection.
 297  */
 298
 299 void
 300 popredir(void)
 301 {
 302         struct redirtab *rp = redirlist;
 303         int i;
 304
 305         for (i = 0 ; i < 10 ; i++) {
 306                 if (rp->renamed[i] != EMPTY) {
 307                         if (i == 0)
 308                                 fd0_redirected--;
 309                         close(i);
 310                         if (rp->renamed[i] >= 0) {
 311                                 copyfd(rp->renamed[i], i);
 312                                 close(rp->renamed[i]);
 313                         }
 314                 }
 315         }
 316         INTOFF;
 317         redirlist = rp->next;
 318         ckfree(rp);
 319         INTON;
 320 }
 321
 322 /*
 323  * Undo all redirections.  Called on error or interrupt.
 324  */
 325
 326 #ifdef mkinit
 327
 328 INCLUDE "redir.h"
 329
 330 RESET {
 331         while (redirlist)
 332                 popredir();
 333 }
 334
 335 SHELLPROC {
 336         clearredir(0);
 337 }
 338
 339 #endif
 340
 341 /* Return true if fd 0 has already been redirected at least once.  */
 342 int
 343 fd0_redirected_p () {
 344         return fd0_redirected != 0;
 345 }
 346
 347 /*
 348  * Discard all saved file descriptors.
 349  */
 350
 351 void
 352 clearredir(vforked)
 353         int vforked;
 354 {
 355         struct redirtab *rp;
 356         int i;
 357
 358         for (rp = redirlist ; rp ; rp = rp->next) {
 359                 for (i = 0 ; i < 10 ; i++) {
 360                         if (rp->renamed[i] >= 0) {
 361                                 close(rp->renamed[i]);
 362                         }
 363                         if (!vforked)
 364                                 rp->renamed[i] = EMPTY;
 365                 }
 366         }
 367 }
 368
 369
 370
 371 /*
 372  * Copy a file descriptor to be >= to.  Returns -1
 373  * if the source file descriptor is closed, EMPTY if there are no unused
 374  * file descriptors left.
 375  */
 376
 377 int
 378 copyfd(int from, int to)
 379 {
 380         int newfd;
 381
 382         newfd = fcntl(from, F_DUPFD, to);
 383         if (newfd < 0) {
 384                 if (errno == EMFILE)
 385                         return EMPTY;
 386                 else
 387                         error("%d: %s", from, strerror(errno));
 388         }
 389         return newfd;
 390 }