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;
73 unsigned int empty_redirs;
77 static struct redirtab *redirlist;
80 * We keep track of whether or not fd0 has been redirected. This is for
81 * background commands, where we want to redirect fd0 to /dev/null only
82 * if it hasn't already been redirected.
84 static int fd0_redirected = 0;
86 /* Number of redirtabs that have not been allocated. */
87 static unsigned int empty_redirs = 0;
89 static void openredirect(union node *, char[10 ]);
90 static int openhere(union node *);
94 * Process a list of redirection commands. If the REDIR_PUSH flag is set,
95 * old file descriptors are stashed away so that the redirection can be
96 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the
97 * standard output, and the standard error if it becomes a duplicate of
98 * stdout, is saved in memory.
100 * We suppress interrupts so that we won't leave open file
101 * descriptors around. Because the signal handler remains
102 * installed and we do not use system call restart, interrupts
103 * will still abort blocking opens such as fifos (they will fail
104 * with EINTR). There is, however, a race condition if an interrupt
105 * arrives after INTOFF and before open blocks.
109 redirect(union node *redir, int flags)
112 struct redirtab *sv = NULL;
115 char memory[10]; /* file descriptors to write to memory */
118 for (i = 10 ; --i >= 0 ; )
120 memory[1] = flags & REDIR_BACKQ;
121 if (flags & REDIR_PUSH) {
124 sv = ckmalloc(sizeof (struct redirtab));
125 for (i = 0 ; i < 10 ; i++)
126 sv->renamed[i] = EMPTY;
127 sv->fd0_redirected = fd0_redirected;
128 sv->empty_redirs = empty_redirs - 1;
129 sv->next = redirlist;
134 for (n = redir ; n ; n = n->nfile.next) {
138 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
140 continue; /* redirect from/to same file descriptor */
142 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
144 if ((i = fcntl(fd, F_DUPFD_CLOEXEC, 10)) == -1) {
151 error("%d: %s", fd, strerror(errno));
158 openredirect(n, memory);
171 openredirect(union node *redir, char memory[10])
174 int fd = redir->nfile.fd;
180 switch (redir->nfile.type) {
182 fname = redir->nfile.expfname;
183 if ((f = open(fname, O_RDONLY)) < 0)
184 error("cannot open %s: %s", fname, strerror(errno));
187 fname = redir->nfile.expfname;
188 if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0)
189 error("cannot create %s: %s", fname, strerror(errno));
193 fname = redir->nfile.expfname;
194 if (stat(fname, &sb) == -1) {
195 if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0)
196 error("cannot create %s: %s", fname, strerror(errno));
197 } else if (!S_ISREG(sb.st_mode)) {
198 if ((f = open(fname, O_WRONLY, 0666)) < 0)
199 error("cannot create %s: %s", fname, strerror(errno));
200 if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) {
202 error("cannot create %s: %s", fname,
206 error("cannot create %s: %s", fname,
212 fname = redir->nfile.expfname;
213 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
214 error("cannot create %s: %s", fname, strerror(errno));
217 fname = redir->nfile.expfname;
218 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
219 error("cannot create %s: %s", fname, strerror(errno));
223 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */
224 if (memory[redir->ndup.dupfd])
227 if (dup2(redir->ndup.dupfd, fd) < 0)
228 error("%d: %s", redir->ndup.dupfd,
243 if (dup2(f, fd) == -1) {
246 error("%d: %s", fd, strerror(e));
254 * Handle here documents. Normally we fork off a process to write the
255 * data to a pipe. If the document is short, we can stuff the data in
256 * the pipe without forking.
260 openhere(union node *redir)
269 error("Pipe call failed: %s", strerror(errno));
271 if (redir->type == NXHERE)
272 p = redir->nhere.expdoc;
274 p = redir->nhere.doc->narg.text;
278 flags = fcntl(pip[1], F_GETFL, 0);
279 if (flags != -1 && fcntl(pip[1], F_SETFL, flags | O_NONBLOCK) != -1) {
280 written = write(pip[1], p, len);
283 if ((size_t)written == len)
285 fcntl(pip[1], F_SETFL, flags);
288 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
290 signal(SIGINT, SIG_IGN);
291 signal(SIGQUIT, SIG_IGN);
292 signal(SIGHUP, SIG_IGN);
293 signal(SIGTSTP, SIG_IGN);
294 signal(SIGPIPE, SIG_DFL);
295 xwrite(pip[1], p + written, len - written);
306 * Undo the effects of the last redirection.
312 struct redirtab *rp = redirlist;
316 if (empty_redirs > 0) {
321 for (i = 0 ; i < 10 ; i++) {
322 if (rp->renamed[i] != EMPTY) {
323 if (rp->renamed[i] >= 0) {
324 dup2(rp->renamed[i], i);
325 close(rp->renamed[i]);
331 fd0_redirected = rp->fd0_redirected;
332 empty_redirs = rp->empty_redirs;
333 redirlist = rp->next;
338 /* Return true if fd 0 has already been redirected at least once. */
340 fd0_redirected_p(void)
342 return fd0_redirected != 0;
346 * Discard all saved file descriptors.
355 for (rp = redirlist ; rp ; rp = rp->next) {
356 for (i = 0 ; i < 10 ; i++) {
357 if (rp->renamed[i] >= 0) {
358 close(rp->renamed[i]);
360 rp->renamed[i] = EMPTY;