commands/ash/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  * 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 /*
  39 #include <sys/cdefs.h>
  40 __FBSDID("$FreeBSD: src/bin/sh/redir.c,v 1.26 2004/04/06 20:06:51 markm Exp $");
  41 */
  42
  43 #include <sys/types.h>
  44 #include <sys/stat.h>
  45 #include <signal.h>
  46 #include <string.h>
  47 #include <fcntl.h>
  48 #include <errno.h>
  49 #include <unistd.h>
  50 #include <stdlib.h>
  51
  52 /*
  53  * Code for dealing with input/output redirection.
  54  */
  55
  56 #include "shell.h"
  57 #include "nodes.h"
  58 #include "jobs.h"
  59 #include "expand.h"
  60 #include "redir.h"
  61 #include "output.h"
  62 #include "memalloc.h"
  63 #include "error.h"
  64 #include "options.h"
  65
  66
  67 #define EMPTY -2                /* marks an unused slot in redirtab */
  68 #define PIPESIZE 4096           /* amount of buffering in a pipe */
  69
  70
  71 MKINIT
  72 struct redirtab {
  73         struct redirtab *next;
  74         int renamed[10];
  75 };
  76
  77
  78 MKINIT struct redirtab *redirlist;
  79
  80 /*
  81  * We keep track of whether or not fd0 has been redirected.  This is for
  82  * background commands, where we want to redirect fd0 to /dev/null only
  83  * if it hasn't already been redirected.
  84 */
  85 STATIC int fd0_redirected = 0;
  86
  87 STATIC void openredirect(union node *, char[10 ]);
  88 STATIC int openhere(union node *);
  89
  90
  91 /*
  92  * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
  93  * old file descriptors are stashed away so that the redirection can be
  94  * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
  95  * standard output, and the standard error if it becomes a duplicate of
  96  * stdout, is saved in memory.
  97  */
  98
  99 void
 100 redirect(union node *redir, int flags)
 101 {
 102         union node *n;
 103         struct redirtab *sv = NULL;
 104         int i;
 105         int fd;
 106         int try;
 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                 try = 0;
 122                 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
 123                     n->ndup.dupfd == fd)
 124                         continue; /* redirect from/to same file descriptor */
 125
 126                 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
 127                         INTOFF;
 128 again:
 129                         if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
 130                                 switch (errno) {
 131                                 case EBADF:
 132                                         if (!try) {
 133                                                 openredirect(n, memory);
 134                                                 try++;
 135                                                 goto again;
 136                                         }
 137                                         /* FALLTHROUGH*/
 138                                 default:
 139                                         INTON;
 140                                         error("%d: %s", fd, strerror(errno));
 141                                         break;
 142                                 }
 143                         }
 144                         if (!try) {
 145                                 sv->renamed[fd] = i;
 146                         }
 147                         INTON;
 148                 }
 149                 if (fd == 0)
 150                         fd0_redirected++;
 151                 if (!try)
 152                         openredirect(n, memory);
 153         }
 154         if (memory[1])
 155                 out1 = &memout;
 156         if (memory[2])
 157                 out2 = &memout;
 158 }
 159
 160
 161 STATIC void
 162 openredirect(union node *redir, char memory[10])
 163 {
 164         struct stat sb;
 165         int fd = redir->nfile.fd;
 166         char *fname;
 167         int f;
 168
 169         /* Assume redirection succeeds. */
 170         { extern int exitstatus; exitstatus = 0; }
 171
 172         /*
 173          * We suppress interrupts so that we won't leave open file
 174          * descriptors around.  This may not be such a good idea because
 175          * an open of a device or a fifo can block indefinitely.
 176          */
 177         INTOFF;
 178         memory[fd] = 0;
 179         switch (redir->nfile.type) {
 180         case NFROM:
 181                 fname = redir->nfile.expfname;
 182                 if ((f = open(fname, O_RDONLY)) < 0)
 183                         error("cannot open %s: %s", fname, strerror(errno));
 184 movefd:
 185                 if (f != fd) {
 186                         dup2(f, fd);
 187                         close(f);
 188                 }
 189                 break;
 190         case NFROMTO:
 191                 fname = redir->nfile.expfname;
 192                 if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0)
 193                         error("cannot create %s: %s", fname, strerror(errno));
 194                 goto movefd;
 195         case NTO:
 196                 fname = redir->nfile.expfname;
 197                 if (Cflag && stat(fname, &sb) != -1 && S_ISREG(sb.st_mode))
 198                         error("cannot create %s: %s", fname,
 199                             strerror(EEXIST));
 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 NCLOBBER:
 204                 fname = redir->nfile.expfname;
 205                 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
 206                         error("cannot create %s: %s", fname, strerror(errno));
 207                 goto movefd;
 208         case NAPPEND:
 209                 fname = redir->nfile.expfname;
 210                 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
 211                         error("cannot create %s: %s", fname, strerror(errno));
 212                 goto movefd;
 213         case NTOFD:
 214         case NFROMFD:
 215                 if (redir->ndup.dupfd >= 0) {   /* if not ">&-" */
 216                         if (memory[redir->ndup.dupfd])
 217                                 memory[fd] = 1;
 218                         else
 219                                 dup2(redir->ndup.dupfd, fd);
 220                 } else {
 221                         close(fd);
 222                 }
 223                 break;
 224         case NHERE:
 225         case NXHERE:
 226                 f = openhere(redir);
 227                 goto movefd;
 228         default:
 229                 abort();
 230         }
 231         INTON;
 232 }
 233
 234
 235 /*
 236  * Handle here documents.  Normally we fork off a process to write the
 237  * data to a pipe.  If the document is short, we can stuff the data in
 238  * the pipe without forking.
 239  */
 240
 241 STATIC int
 242 openhere(union node *redir)
 243 {
 244         int pip[2];
 245         int len = 0;
 246
 247         if (pipe(pip) < 0)
 248                 error("Pipe call failed: %s", strerror(errno));
 249         if (redir->type == NHERE) {
 250                 len = strlen(redir->nhere.doc->narg.text);
 251                 if (len <= PIPESIZE) {
 252                         xwrite(pip[1], redir->nhere.doc->narg.text, len);
 253                         goto out;
 254                 }
 255         }
 256         if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
 257                 close(pip[0]);
 258                 signal(SIGINT, SIG_IGN);
 259                 signal(SIGQUIT, SIG_IGN);
 260                 signal(SIGHUP, SIG_IGN);
 261                 signal(SIGTSTP, SIG_IGN);
 262                 signal(SIGPIPE, SIG_DFL);
 263                 if (redir->type == NHERE)
 264                         xwrite(pip[1], redir->nhere.doc->narg.text, len);
 265                 else
 266                         expandhere(redir->nhere.doc, pip[1]);
 267                 _exit(0);
 268         }
 269 out:
 270         close(pip[1]);
 271         return pip[0];
 272 }
 273
 274
 275
 276 /*
 277  * Undo the effects of the last redirection.
 278  */
 279
 280 void
 281 popredir(void)
 282 {
 283         struct redirtab *rp = redirlist;
 284         int i;
 285
 286         for (i = 0 ; i < 10 ; i++) {
 287                 if (rp->renamed[i] != EMPTY) {
 288                         if (i == 0)
 289                                 fd0_redirected--;
 290                         if (rp->renamed[i] >= 0) {
 291                                 dup2(rp->renamed[i], i);
 292                                 close(rp->renamed[i]);
 293                         } else {
 294                                 close(i);
 295                         }
 296                 }
 297         }
 298         INTOFF;
 299         redirlist = rp->next;
 300         ckfree(rp);
 301         INTON;
 302 }
 303
 304 /*
 305  * Undo all redirections.  Called on error or interrupt.
 306  */
 307
 308 #ifdef mkinit
 309
 310 INCLUDE "redir.h"
 311
 312 RESET {
 313         while (redirlist)
 314                 popredir();
 315 }
 316
 317 SHELLPROC {
 318         clearredir();
 319 }
 320
 321 #endif
 322
 323 /* Return true if fd 0 has already been redirected at least once.  */
 324 int
 325 fd0_redirected_p(void)
 326 {
 327         return fd0_redirected != 0;
 328 }
 329
 330 /*
 331  * Discard all saved file descriptors.
 332  */
 333
 334 void
 335 clearredir(void)
 336 {
 337         struct redirtab *rp;
 338         int i;
 339
 340         for (rp = redirlist ; rp ; rp = rp->next) {
 341                 for (i = 0 ; i < 10 ; i++) {
 342                         if (rp->renamed[i] >= 0) {
 343                                 close(rp->renamed[i]);
 344                         }
 345                         rp->renamed[i] = EMPTY;
 346                 }
 347         }
 348 }
 349
 350 /*
 351  * $PchId: redir.c,v 1.5 2006/05/22 12:27:37 philip Exp $
 352  */