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. 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_MAYBE, 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 #if !defined(O_CLOEXEC) || !defined(F_DUPFD_CLOEXEC)
 147                         else {
 148                                 fcntl(i, F_SETFD, FD_CLOEXEC);
 149                         }
 150 #endif
 151                         sv->renamed[fd] = i;
 152                         INTON;
 153                 }
 154                 openredirect(n, memory);
 155                 INTON;
 156                 INTOFF;
 157         }
 158         if (memory[1])
 159                 out1 = &memout;
 160         if (memory[2])
 161                 out2 = &memout;
 162         INTON;
 163 }
 164
 165
 166 static void
 167 openredirect(union node *redir, char memory[10])
 168 {
 169         struct stat sb;
 170         int fd = redir->nfile.fd;
 171         const char *fname;
 172         int f;
 173         int e;
 174
 175         memory[fd] = 0;
 176         switch (redir->nfile.type) {
 177         case NFROM:
 178                 fname = redir->nfile.expfname;
 179                 if ((f = open(fname, O_RDONLY)) < 0)
 180                         error("cannot open %s: %s", fname, strerror(errno));
 181                 break;
 182         case NFROMTO:
 183                 fname = redir->nfile.expfname;
 184                 if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0)
 185                         error("cannot create %s: %s", fname, strerror(errno));
 186                 break;
 187         case NTO:
 188                 if (Cflag) {
 189                         fname = redir->nfile.expfname;
 190                         if (stat(fname, &sb) == -1) {
 191                                 if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0)
 192                                         error("cannot create %s: %s", fname, strerror(errno));
 193                         } else if (!S_ISREG(sb.st_mode)) {
 194                                 if ((f = open(fname, O_WRONLY, 0666)) < 0)
 195                                         error("cannot create %s: %s", fname, strerror(errno));
 196                                 if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) {
 197                                         close(f);
 198                                         error("cannot create %s: %s", fname,
 199                                             strerror(EEXIST));
 200                                 }
 201                         } else
 202                                 error("cannot create %s: %s", fname,
 203                                     strerror(EEXIST));
 204                         break;
 205                 }
 206                 /* FALLTHROUGH */
 207         case NCLOBBER:
 208                 fname = redir->nfile.expfname;
 209                 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
 210                         error("cannot create %s: %s", fname, strerror(errno));
 211                 break;
 212         case NAPPEND:
 213                 fname = redir->nfile.expfname;
 214                 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
 215                         error("cannot create %s: %s", fname, strerror(errno));
 216                 break;
 217         case NTOFD:
 218         case NFROMFD:
 219                 if (redir->ndup.dupfd >= 0) {   /* if not ">&-" */
 220                         if (memory[redir->ndup.dupfd])
 221                                 memory[fd] = 1;
 222                         else {
 223                                 if (dup2(redir->ndup.dupfd, fd) < 0)
 224                                         error("%d: %s", redir->ndup.dupfd,
 225                                                         strerror(errno));
 226                         }
 227                 } else {
 228                         close(fd);
 229                 }
 230                 return;
 231         case NHERE:
 232         case NXHERE:
 233                 f = openhere(redir);
 234                 break;
 235         default:
 236                 abort();
 237         }
 238         if (f != fd) {
 239                 if (dup2(f, fd) == -1) {
 240                         e = errno;
 241                         close(f);
 242                         error("%d: %s", fd, strerror(e));
 243                 }
 244                 close(f);
 245         }
 246 }
 247
 248
 249 /*
 250  * Handle here documents.  Normally we fork off a process to write the
 251  * data to a pipe.  If the document is short, we can stuff the data in
 252  * the pipe without forking.
 253  */
 254
 255 static int
 256 openhere(union node *redir)
 257 {
 258         const char *p;
 259         int pip[2];
 260         size_t len = 0;
 261         int flags;
 262         ssize_t written = 0;
 263
 264         if (pipe(pip) < 0)
 265                 error("Pipe call failed: %s", strerror(errno));
 266
 267         if (redir->type == NXHERE)
 268                 p = redir->nhere.expdoc;
 269         else
 270                 p = redir->nhere.doc->narg.text;
 271         len = strlen(p);
 272         if (len == 0)
 273                 goto out;
 274         flags = fcntl(pip[1], F_GETFL, 0);
 275         if (flags != -1 && fcntl(pip[1], F_SETFL, flags | O_NONBLOCK) != -1) {
 276                 written = write(pip[1], p, len);
 277                 if (written < 0)
 278                         written = 0;
 279                 if ((size_t)written == len)
 280                         goto out;
 281                 fcntl(pip[1], F_SETFL, flags);
 282         }
 283
 284         if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
 285                 close(pip[0]);
 286                 signal(SIGINT, SIG_IGN);
 287                 signal(SIGQUIT, SIG_IGN);
 288                 signal(SIGHUP, SIG_IGN);
 289                 signal(SIGTSTP, SIG_IGN);
 290                 signal(SIGPIPE, SIG_DFL);
 291                 xwrite(pip[1], p + written, len - written);
 292                 _exit(0);
 293         }
 294 out:
 295         close(pip[1]);
 296         return pip[0];
 297 }
 298
 299
 300
 301 /*
 302  * Undo the effects of the last redirection.
 303  */
 304
 305 void
 306 popredir(void)
 307 {
 308         struct redirtab *rp = redirlist;
 309         int i;
 310
 311         for (i = 0 ; i < 10 ; i++) {
 312                 if (rp->renamed[i] != EMPTY) {
 313                         if (rp->renamed[i] >= 0) {
 314                                 dup2(rp->renamed[i], i);
 315                                 close(rp->renamed[i]);
 316                         } else {
 317                                 close(i);
 318                         }
 319                 }
 320         }
 321         INTOFF;
 322         fd0_redirected = rp->fd0_redirected;
 323         redirlist = rp->next;
 324         ckfree(rp);
 325         INTON;
 326 }
 327
 328 /* Return true if fd 0 has already been redirected at least once.  */
 329 int
 330 fd0_redirected_p(void)
 331 {
 332         return fd0_redirected != 0;
 333 }
 334
 335 /*
 336  * Discard all saved file descriptors.
 337  */
 338
 339 void
 340 clearredir(void)
 341 {
 342         struct redirtab *rp;
 343         int i;
 344
 345         for (rp = redirlist ; rp ; rp = rp->next) {
 346                 for (i = 0 ; i < 10 ; i++) {
 347                         if (rp->renamed[i] >= 0) {
 348                                 close(rp->renamed[i]);
 349                         }
 350                         rp->renamed[i] = EMPTY;
 351                 }
 352         }
 353 }