2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
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35 static char sccsid[] = "@(#)redir.c 8.2 (Berkeley) 5/4/95";
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
41 #include <sys/types.h>
51 * Code for dealing with input/output redirection.
65 #define EMPTY -2 /* marks an unused slot in redirtab */
66 #define CLOSED -1 /* fd was not open before redir */
70 struct redirtab *next;
75 static struct redirtab *redirlist;
78 * We keep track of whether or not fd0 has been redirected. This is for
79 * background commands, where we want to redirect fd0 to /dev/null only
80 * if it hasn't already been redirected.
82 static int fd0_redirected = 0;
84 static void openredirect(union node *, char[10 ]);
85 static int openhere(union node *);
89 * Process a list of redirection commands. If the REDIR_PUSH flag is set,
90 * old file descriptors are stashed away so that the redirection can be
91 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the
92 * standard output, and the standard error if it becomes a duplicate of
93 * stdout, is saved in memory.
97 redirect(union node *redir, int flags)
100 struct redirtab *sv = NULL;
103 char memory[10]; /* file descriptors to write to memory */
105 for (i = 10 ; --i >= 0 ; )
107 memory[1] = flags & REDIR_BACKQ;
108 if (flags & REDIR_PUSH) {
109 sv = ckmalloc(sizeof (struct redirtab));
110 for (i = 0 ; i < 10 ; i++)
111 sv->renamed[i] = EMPTY;
112 sv->next = redirlist;
115 for (n = redir ; n ; n = n->nfile.next) {
117 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
119 continue; /* redirect from/to same file descriptor */
121 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
123 if ((i = fcntl(fd, F_DUPFD_CLOEXEC, 10)) == -1) {
130 error("%d: %s", fd, strerror(errno));
139 openredirect(n, memory);
149 openredirect(union node *redir, char memory[10])
152 int fd = redir->nfile.fd;
158 * We suppress interrupts so that we won't leave open file
159 * descriptors around. Because the signal handler remains
160 * installed and we do not use system call restart, interrupts
161 * will still abort blocking opens such as fifos (they will fail
162 * with EINTR). There is, however, a race condition if an interrupt
163 * arrives after INTOFF and before open blocks.
167 switch (redir->nfile.type) {
169 fname = redir->nfile.expfname;
170 if ((f = open(fname, O_RDONLY)) < 0)
171 error("cannot open %s: %s", fname, strerror(errno));
174 if (dup2(f, fd) == -1) {
177 error("%d: %s", fd, strerror(e));
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));
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)) {
198 error("cannot create %s: %s", fname,
202 error("cannot create %s: %s", fname,
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));
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));
219 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */
220 if (memory[redir->ndup.dupfd])
223 if (dup2(redir->ndup.dupfd, fd) < 0)
224 error("%d: %s", redir->ndup.dupfd,
243 * Handle here documents. Normally we fork off a process to write the
244 * data to a pipe. If the document is short, we can stuff the data in
245 * the pipe without forking.
249 openhere(union node *redir)
258 error("Pipe call failed: %s", strerror(errno));
260 if (redir->type == NXHERE)
261 p = redir->nhere.expdoc;
263 p = redir->nhere.doc->narg.text;
267 flags = fcntl(pip[1], F_GETFL, 0);
268 if (flags != -1 && fcntl(pip[1], F_SETFL, flags | O_NONBLOCK) != -1) {
269 written = write(pip[1], p, len);
272 if ((size_t)written == len)
274 fcntl(pip[1], F_SETFL, flags);
277 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
279 signal(SIGINT, SIG_IGN);
280 signal(SIGQUIT, SIG_IGN);
281 signal(SIGHUP, SIG_IGN);
282 signal(SIGTSTP, SIG_IGN);
283 signal(SIGPIPE, SIG_DFL);
284 xwrite(pip[1], p + written, len - written);
295 * Undo the effects of the last redirection.
301 struct redirtab *rp = redirlist;
304 for (i = 0 ; i < 10 ; i++) {
305 if (rp->renamed[i] != EMPTY) {
308 if (rp->renamed[i] >= 0) {
309 dup2(rp->renamed[i], i);
310 close(rp->renamed[i]);
317 redirlist = rp->next;
322 /* Return true if fd 0 has already been redirected at least once. */
324 fd0_redirected_p(void)
326 return fd0_redirected != 0;
330 * Discard all saved file descriptors.
339 for (rp = redirlist ; rp ; rp = rp->next) {
340 for (i = 0 ; i < 10 ; i++) {
341 if (rp->renamed[i] >= 0) {
342 close(rp->renamed[i]);
344 rp->renamed[i] = EMPTY;