bin/sh/redir.c

   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  * @(#)redir.c  8.2 (Berkeley) 5/4/95
  37  * $FreeBSD: src/bin/sh/redir.c,v 1.26 2004/04/06 20:06:51 markm Exp $
  38  * $DragonFly: src/bin/sh/redir.c,v 1.5 2007/01/14 05:48:08 pavalos Exp $
  39  */
  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 }