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
  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 #include <sys/cdefs.h>
  39 __FBSDID("$FreeBSD$");
  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 CLOSED -1               /* fd was not open before redir */
  67
  68
  69 struct redirtab {
  70         struct redirtab *next;
  71         int renamed[10];
  72         int fd0_redirected;
  73 };
  74
  75
  76 static 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  * We suppress interrupts so that we won't leave open file
  97  * descriptors around.  Because the signal handler remains
  98  * installed and we do not use system call restart, interrupts
  99  * will still abort blocking opens such as fifos (they will fail
 100  * with EINTR). There is, however, a race condition if an interrupt
 101  * arrives after INTOFF and before open blocks.
 102  */
 103
 104 void
 105 redirect(union node *redir, int flags)
 106 {
 107         union node *n;
 108         struct redirtab *sv = NULL;
 109         int i;
 110         int fd;
 111         char memory[10];        /* file descriptors to write to memory */
 112
 113         INTOFF;
 114         for (i = 10 ; --i >= 0 ; )
 115                 memory[i] = 0;
 116         memory[1] = flags & REDIR_BACKQ;
 117         if (flags & REDIR_PUSH) {
 118                 sv = ckmalloc(sizeof (struct redirtab));
 119                 for (i = 0 ; i < 10 ; i++)
 120                         sv->renamed[i] = EMPTY;
 121                 sv->fd0_redirected = fd0_redirected;
 122                 sv->next = redirlist;
 123                 redirlist = sv;
 124         }
 125         for (n = redir ; n ; n = n->nfile.next) {
 126                 fd = n->nfile.fd;
 127                 if (fd == 0)
 128                         fd0_redirected = 1;
 129                 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
 130                     n->ndup.dupfd == fd)
 131                         continue; /* redirect from/to same file descriptor */
 132
 133                 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
 134                         INTOFF;
 135                         if ((i = fcntl(fd, F_DUPFD_CLOEXEC, 10)) == -1) {
 136                                 switch (errno) {
 137                                 case EBADF:
 138                                         i = CLOSED;
 139                                         break;
 140                                 default:
 141                                         INTON;
 142                                         error("%d: %s", fd, strerror(errno));
 143                                         break;
 144                                 }
 145                         }
 146                         sv->renamed[fd] = i;
 147                         INTON;
 148                 }
 149                 openredirect(n, memory);
 150                 INTON;
 151                 INTOFF;
 152         }
 153         if (memory[1])
 154                 out1 = &memout;
 155         if (memory[2])
 156                 out2 = &memout;
 157         INTON;
 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         const char *fname;
 167         int f;
 168         int e;
 169
 170         memory[fd] = 0;
 171         switch (redir->nfile.type) {
 172         case NFROM:
 173                 fname = redir->nfile.expfname;
 174                 if ((f = open(fname, O_RDONLY)) < 0)
 175                         error("cannot open %s: %s", fname, strerror(errno));
 176                 break;
 177         case NFROMTO:
 178                 fname = redir->nfile.expfname;
 179                 if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0)
 180                         error("cannot create %s: %s", fname, strerror(errno));
 181                 break;
 182         case NTO:
 183                 if (Cflag) {
 184                         fname = redir->nfile.expfname;
 185                         if (stat(fname, &sb) == -1) {
 186                                 if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0)
 187                                         error("cannot create %s: %s", fname, strerror(errno));
 188                         } else if (!S_ISREG(sb.st_mode)) {
 189                                 if ((f = open(fname, O_WRONLY, 0666)) < 0)
 190                                         error("cannot create %s: %s", fname, strerror(errno));
 191                                 if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) {
 192                                         close(f);
 193                                         error("cannot create %s: %s", fname,
 194                                             strerror(EEXIST));
 195                                 }
 196                         } else
 197                                 error("cannot create %s: %s", fname,
 198                                     strerror(EEXIST));
 199                         break;
 200                 }
 201                 /* FALLTHROUGH */
 202         case NCLOBBER:
 203                 fname = redir->nfile.expfname;
 204                 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
 205                         error("cannot create %s: %s", fname, strerror(errno));
 206                 break;
 207         case NAPPEND:
 208                 fname = redir->nfile.expfname;
 209                 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
 210                         error("cannot create %s: %s", fname, strerror(errno));
 211                 break;
 212         case NTOFD:
 213         case NFROMFD:
 214                 if (redir->ndup.dupfd >= 0) {   /* if not ">&-" */
 215                         if (memory[redir->ndup.dupfd])
 216                                 memory[fd] = 1;
 217                         else {
 218                                 if (dup2(redir->ndup.dupfd, fd) < 0)
 219                                         error("%d: %s", redir->ndup.dupfd,
 220                                                         strerror(errno));
 221                         }
 222                 } else {
 223                         close(fd);
 224                 }
 225                 return;
 226         case NHERE:
 227         case NXHERE:
 228                 f = openhere(redir);
 229                 break;
 230         default:
 231                 abort();
 232         }
 233         if (f != fd) {
 234                 if (dup2(f, fd) == -1) {
 235                         e = errno;
 236                         close(f);
 237                         error("%d: %s", fd, strerror(e));
 238                 }
 239                 close(f);
 240         }
 241 }
 242
 243
 244 /*
 245  * Handle here documents.  Normally we fork off a process to write the
 246  * data to a pipe.  If the document is short, we can stuff the data in
 247  * the pipe without forking.
 248  */
 249
 250 static int
 251 openhere(union node *redir)
 252 {
 253         const char *p;
 254         int pip[2];
 255         size_t len = 0;
 256         int flags;
 257         ssize_t written = 0;
 258
 259         if (pipe(pip) < 0)
 260                 error("Pipe call failed: %s", strerror(errno));
 261
 262         if (redir->type == NXHERE)
 263                 p = redir->nhere.expdoc;
 264         else
 265                 p = redir->nhere.doc->narg.text;
 266         len = strlen(p);
 267         if (len == 0)
 268                 goto out;
 269         flags = fcntl(pip[1], F_GETFL, 0);
 270         if (flags != -1 && fcntl(pip[1], F_SETFL, flags | O_NONBLOCK) != -1) {
 271                 written = write(pip[1], p, len);
 272                 if (written < 0)
 273                         written = 0;
 274                 if ((size_t)written == len)
 275                         goto out;
 276                 fcntl(pip[1], F_SETFL, flags);
 277         }
 278
 279         if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
 280                 close(pip[0]);
 281                 signal(SIGINT, SIG_IGN);
 282                 signal(SIGQUIT, SIG_IGN);
 283                 signal(SIGHUP, SIG_IGN);
 284                 signal(SIGTSTP, SIG_IGN);
 285                 signal(SIGPIPE, SIG_DFL);
 286                 xwrite(pip[1], p + written, len - written);
 287                 _exit(0);
 288         }
 289 out:
 290         close(pip[1]);
 291         return pip[0];
 292 }
 293
 294
 295
 296 /*
 297  * Undo the effects of the last redirection.
 298  */
 299
 300 void
 301 popredir(void)
 302 {
 303         struct redirtab *rp = redirlist;
 304         int i;
 305
 306         for (i = 0 ; i < 10 ; i++) {
 307                 if (rp->renamed[i] != EMPTY) {
 308                         if (rp->renamed[i] >= 0) {
 309                                 dup2(rp->renamed[i], i);
 310                                 close(rp->renamed[i]);
 311                         } else {
 312                                 close(i);
 313                         }
 314                 }
 315         }
 316         INTOFF;
 317         fd0_redirected = rp->fd0_redirected;
 318         redirlist = rp->next;
 319         ckfree(rp);
 320         INTON;
 321 }
 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 }