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;
76 static struct redirtab *redirlist;
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.
83 static int fd0_redirected = 0;
85 static void openredirect(union node *, char[10 ]);
86 static int openhere(union node *);
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.
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.
105 redirect(union node *redir, int flags)
108 struct redirtab *sv = NULL;
111 char memory[10]; /* file descriptors to write to memory */
114 for (i = 10 ; --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;
125 for (n = redir ; n ; n = n->nfile.next) {
129 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
131 continue; /* redirect from/to same file descriptor */
133 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
135 if ((i = fcntl(fd, F_DUPFD_CLOEXEC, 10)) == -1) {
142 error("%d: %s", fd, strerror(errno));
149 openredirect(n, memory);
162 openredirect(union node *redir, char memory[10])
165 int fd = redir->nfile.fd;
171 switch (redir->nfile.type) {
173 fname = redir->nfile.expfname;
174 if ((f = open(fname, O_RDONLY)) < 0)
175 error("cannot open %s: %s", fname, strerror(errno));
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));
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)) {
193 error("cannot create %s: %s", fname,
197 error("cannot create %s: %s", fname,
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));
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));
214 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */
215 if (memory[redir->ndup.dupfd])
218 if (dup2(redir->ndup.dupfd, fd) < 0)
219 error("%d: %s", redir->ndup.dupfd,
234 if (dup2(f, fd) == -1) {
237 error("%d: %s", fd, strerror(e));
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.
251 openhere(union node *redir)
260 error("Pipe call failed: %s", strerror(errno));
262 if (redir->type == NXHERE)
263 p = redir->nhere.expdoc;
265 p = redir->nhere.doc->narg.text;
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);
274 if ((size_t)written == len)
276 fcntl(pip[1], F_SETFL, flags);
279 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 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);
297 * Undo the effects of the last redirection.
303 struct redirtab *rp = redirlist;
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]);
317 fd0_redirected = rp->fd0_redirected;
318 redirlist = rp->next;
323 /* Return true if fd 0 has already been redirected at least once. */
325 fd0_redirected_p(void)
327 return fd0_redirected != 0;
331 * Discard all saved file descriptors.
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]);
345 rp->renamed[i] = EMPTY;