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  * 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  * @(#)redir.c  8.2 (Berkeley) 5/4/95
  33  * $FreeBSD: head/bin/sh/redir.c 246288 2013-02-03 15:54:57Z jilles $
  34  */
  35
  36 #include <sys/types.h>
  37 #include <sys/stat.h>
  38 #include <signal.h>
  39 #include <string.h>
  40 #include <fcntl.h>
  41 #include <errno.h>
  42 #include <unistd.h>
  43 #include <stdlib.h>
  44
  45 /*
  46  * Code for dealing with input/output redirection.
  47  */
  48
  49 #include "shell.h"
  50 #include "nodes.h"
  51 #include "jobs.h"
  52 #include "expand.h"
  53 #include "redir.h"
  54 #include "output.h"
  55 #include "memalloc.h"
  56 #include "error.h"
  57 #include "options.h"
  58
  59
  60 #define EMPTY -2                /* marks an unused slot in redirtab */
  61 #define CLOSED -1               /* fd was not open before redir */
  62 #define PIPESIZE 4096           /* amount of buffering in a pipe */
  63
  64
  65 MKINIT
  66 struct redirtab {
  67         struct redirtab *next;
  68         int renamed[10];
  69 };
  70
  71
  72 MKINIT struct redirtab *redirlist;
  73
  74 /*
  75  * We keep track of whether or not fd0 has been redirected.  This is for
  76  * background commands, where we want to redirect fd0 to /dev/null only
  77  * if it hasn't already been redirected.
  78 */
  79 static int fd0_redirected = 0;
  80
  81 static void openredirect(union node *, char[10 ]);
  82 static int openhere(union node *);
  83
  84
  85 /*
  86  * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
  87  * old file descriptors are stashed away so that the redirection can be
  88  * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
  89  * standard output, and the standard error if it becomes a duplicate of
  90  * stdout, is saved in memory.
  91  */
  92
  93 void
  94 redirect(union node *redir, int flags)
  95 {
  96         union node *n;
  97         struct redirtab *sv = NULL;
  98         int i;
  99         int fd;
 100         char memory[10];        /* file descriptors to write to memory */
 101
 102         for (i = 10 ; --i >= 0 ; )
 103                 memory[i] = 0;
 104         memory[1] = flags & REDIR_BACKQ;
 105         if (flags & REDIR_PUSH) {
 106                 sv = ckmalloc(sizeof (struct redirtab));
 107                 for (i = 0 ; i < 10 ; i++)
 108                         sv->renamed[i] = EMPTY;
 109                 sv->next = redirlist;
 110                 redirlist = sv;
 111         }
 112         for (n = redir ; n ; n = n->nfile.next) {
 113                 fd = n->nfile.fd;
 114                 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
 115                     n->ndup.dupfd == fd)
 116                         continue; /* redirect from/to same file descriptor */
 117
 118                 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
 119                         INTOFF;
 120                         if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
 121                                 switch (errno) {
 122                                 case EBADF:
 123                                         i = CLOSED;
 124                                         break;
 125                                 default:
 126                                         INTON;
 127                                         error("%d: %s", fd, strerror(errno));
 128                                         break;
 129                                 }
 130                         } else
 131                                 (void)fcntl(i, F_SETFD, FD_CLOEXEC);
 132                         sv->renamed[fd] = i;
 133                         INTON;
 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
 146 static void
 147 openredirect(union node *redir, char memory[10])
 148 {
 149         struct stat sb;
 150         int fd = redir->nfile.fd;
 151         char *fname;
 152         int f = 0;
 153         int e;
 154
 155         /*
 156          * We suppress interrupts so that we won't leave open file
 157          * descriptors around.  Because the signal handler remains
 158          * installed and we do not use system call restart, interrupts
 159          * will still abort blocking opens such as fifos (they will fail
 160          * with EINTR). There is, however, a race condition if an interrupt
 161          * arrives after INTOFF and before open blocks.
 162          */
 163         INTOFF;
 164         memory[fd] = 0;
 165         switch (redir->nfile.type) {
 166         case NFROM:
 167                 fname = redir->nfile.expfname;
 168                 if ((f = open(fname, O_RDONLY)) < 0)
 169                         error("cannot open %s: %s", fname, strerror(errno));
 170 movefd:
 171                 if (f != fd) {
 172                         if (dup2(f, fd) == -1) {
 173                                 e = errno;
 174                                 close(f);
 175                                 error("%d: %s", fd, strerror(e));
 176                         }
 177                         close(f);
 178                 }
 179                 break;
 180         case NFROMTO:
 181                 fname = redir->nfile.expfname;
 182                 if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0)
 183                         error("cannot create %s: %s", fname, strerror(errno));
 184                 goto movefd;
 185         case NTO:
 186                 if (Cflag) {
 187                         fname = redir->nfile.expfname;
 188                         if (stat(fname, &sb) == -1) {
 189                                 if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0)
 190                                         error("cannot create %s: %s", fname, strerror(errno));
 191                         } else if (!S_ISREG(sb.st_mode)) {
 192                                 if ((f = open(fname, O_WRONLY, 0666)) < 0)
 193                                         error("cannot create %s: %s", fname, strerror(errno));
 194                                 if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) {
 195                                         close(f);
 196                                         error("cannot create %s: %s", fname,
 197                                             strerror(EEXIST));
 198                                 }
 199                         } else
 200                                 error("cannot create %s: %s", fname,
 201                                     strerror(EEXIST));
 202                         goto movefd;
 203                 }
 204                 /* FALLTHROUGH */
 205         case NCLOBBER:
 206                 fname = redir->nfile.expfname;
 207                 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
 208                         error("cannot create %s: %s", fname, strerror(errno));
 209                 goto movefd;
 210         case NAPPEND:
 211                 fname = redir->nfile.expfname;
 212                 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
 213                         error("cannot create %s: %s", fname, strerror(errno));
 214                 goto movefd;
 215         case NTOFD:
 216         case NFROMFD:
 217                 if (redir->ndup.dupfd >= 0) {   /* if not ">&-" */
 218                         if (memory[redir->ndup.dupfd])
 219                                 memory[fd] = 1;
 220                         else {
 221                                 if (dup2(redir->ndup.dupfd, fd) < 0)
 222                                         error("%d: %s", redir->ndup.dupfd,
 223                                                         strerror(errno));
 224                         }
 225                 } else {
 226                         close(fd);
 227                 }
 228                 break;
 229         case NHERE:
 230         case NXHERE:
 231                 f = openhere(redir);
 232                 goto movefd;
 233         default:
 234                 abort();
 235         }
 236         INTON;
 237 }
 238
 239
 240 /*
 241  * Handle here documents.  Normally we fork off a process to write the
 242  * data to a pipe.  If the document is short, we can stuff the data in
 243  * the pipe without forking.
 244  */
 245
 246 static int
 247 openhere(union node *redir)
 248 {
 249         char *p;
 250         int pip[2];
 251         int len = 0;
 252
 253         if (pipe(pip) < 0)
 254                 error("Pipe call failed: %s", strerror(errno));
 255
 256         if (redir->type == NXHERE)
 257                 p = redir->nhere.expdoc;
 258         else
 259                 p = redir->nhere.doc->narg.text;
 260         len = strlen(p);
 261         if (len <= PIPESIZE) {
 262                 xwrite(pip[1], p, len);
 263                 goto out;
 264         }
 265
 266         if (forkshell(NULL, NULL, FORK_NOJOB) == 0) {
 267                 close(pip[0]);
 268                 signal(SIGINT, SIG_IGN);
 269                 signal(SIGQUIT, SIG_IGN);
 270                 signal(SIGHUP, SIG_IGN);
 271                 signal(SIGTSTP, SIG_IGN);
 272                 signal(SIGPIPE, SIG_DFL);
 273                 xwrite(pip[1], p, len);
 274                 _exit(0);
 275         }
 276 out:
 277         close(pip[1]);
 278         return pip[0];
 279 }
 280
 281
 282
 283 /*
 284  * Undo the effects of the last redirection.
 285  */
 286
 287 void
 288 popredir(void)
 289 {
 290         struct redirtab *rp = redirlist;
 291         int i;
 292
 293         for (i = 0 ; i < 10 ; i++) {
 294                 if (rp->renamed[i] != EMPTY) {
 295                         if (i == 0)
 296                                 fd0_redirected--;
 297                         if (rp->renamed[i] >= 0) {
 298                                 dup2(rp->renamed[i], i);
 299                                 close(rp->renamed[i]);
 300                         } else {
 301                                 close(i);
 302                         }
 303                 }
 304         }
 305         INTOFF;
 306         redirlist = rp->next;
 307         ckfree(rp);
 308         INTON;
 309 }
 310
 311 /*
 312  * Undo all redirections.  Called on error or interrupt.
 313  */
 314
 315 #ifdef mkinit
 316
 317 INCLUDE "redir.h"
 318
 319 RESET {
 320         while (redirlist)
 321                 popredir();
 322 }
 323
 324 #endif
 325
 326 /* Return true if fd 0 has already been redirected at least once.  */
 327 int
 328 fd0_redirected_p(void)
 329 {
 330         return fd0_redirected != 0;
 331 }
 332
 333 /*
 334  * Discard all saved file descriptors.
 335  */
 336
 337 void
 338 clearredir(void)
 339 {
 340         struct redirtab *rp;
 341         int i;
 342
 343         for (rp = redirlist ; rp ; rp = rp->next) {
 344                 for (i = 0 ; i < 10 ; i++) {
 345                         if (rp->renamed[i] >= 0) {
 346                                 close(rp->renamed[i]);
 347                         }
 348                         rp->renamed[i] = EMPTY;
 349                 }
 350         }
 351 }