/*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1991, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Kenneth Almquist. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include #include #include #include #include #include #include #include /* * Code for dealing with input/output redirection. */ #include "shell.h" #include "nodes.h" #include "jobs.h" #include "expand.h" #include "redir.h" #include "output.h" #include "memalloc.h" #include "error.h" #include "options.h" #define EMPTY -2 /* marks an unused slot in redirtab */ #define CLOSED -1 /* fd was not open before redir */ struct redirtab { struct redirtab *next; int renamed[10]; int fd0_redirected; unsigned int empty_redirs; }; static struct redirtab *redirlist; /* * We keep track of whether or not fd0 has been redirected. This is for * background commands, where we want to redirect fd0 to /dev/null only * if it hasn't already been redirected. */ static int fd0_redirected = 0; /* Number of redirtabs that have not been allocated. */ static unsigned int empty_redirs = 0; static void openredirect(union node *, char[10 ]); static int openhere(union node *); /* * Process a list of redirection commands. If the REDIR_PUSH flag is set, * old file descriptors are stashed away so that the redirection can be * undone by calling popredir. If the REDIR_BACKQ flag is set, then the * standard output, and the standard error if it becomes a duplicate of * stdout, is saved in memory. * * We suppress interrupts so that we won't leave open file * descriptors around. Because the signal handler remains * installed and we do not use system call restart, interrupts * will still abort blocking opens such as fifos (they will fail * with EINTR). There is, however, a race condition if an interrupt * arrives after INTOFF and before open blocks. */ void redirect(union node *redir, int flags) { union node *n; struct redirtab *sv = NULL; int i; int fd; char memory[10]; /* file descriptors to write to memory */ INTOFF; for (i = 10 ; --i >= 0 ; ) memory[i] = 0; memory[1] = flags & REDIR_BACKQ; if (flags & REDIR_PUSH) { empty_redirs++; if (redir != NULL) { sv = ckmalloc(sizeof (struct redirtab)); for (i = 0 ; i < 10 ; i++) sv->renamed[i] = EMPTY; sv->fd0_redirected = fd0_redirected; sv->empty_redirs = empty_redirs - 1; sv->next = redirlist; redirlist = sv; empty_redirs = 0; } } for (n = redir ; n ; n = n->nfile.next) { fd = n->nfile.fd; if (fd == 0) fd0_redirected = 1; if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) && n->ndup.dupfd == fd) continue; /* redirect from/to same file descriptor */ if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) { INTOFF; if ((i = fcntl(fd, F_DUPFD_CLOEXEC, 10)) == -1) { switch (errno) { case EBADF: i = CLOSED; break; default: INTON; error("%d: %s", fd, strerror(errno)); break; } } sv->renamed[fd] = i; INTON; } openredirect(n, memory); INTON; INTOFF; } if (memory[1]) out1 = &memout; if (memory[2]) out2 = &memout; INTON; } static void openredirect(union node *redir, char memory[10]) { struct stat sb; int fd = redir->nfile.fd; const char *fname; int f; int e; memory[fd] = 0; switch (redir->nfile.type) { case NFROM: fname = redir->nfile.expfname; if ((f = open(fname, O_RDONLY)) < 0) error("cannot open %s: %s", fname, strerror(errno)); break; case NFROMTO: fname = redir->nfile.expfname; if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0) error("cannot create %s: %s", fname, strerror(errno)); break; case NTO: if (Cflag) { fname = redir->nfile.expfname; if (stat(fname, &sb) == -1) { if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0) error("cannot create %s: %s", fname, strerror(errno)); } else if (!S_ISREG(sb.st_mode)) { if ((f = open(fname, O_WRONLY, 0666)) < 0) error("cannot create %s: %s", fname, strerror(errno)); if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) { close(f); error("cannot create %s: %s", fname, strerror(EEXIST)); } } else error("cannot create %s: %s", fname, strerror(EEXIST)); break; } /* FALLTHROUGH */ case NCLOBBER: fname = redir->nfile.expfname; if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0) error("cannot create %s: %s", fname, strerror(errno)); break; case NAPPEND: fname = redir->nfile.expfname; if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0) error("cannot create %s: %s", fname, strerror(errno)); break; case NTOFD: case NFROMFD: if (redir->ndup.dupfd >= 0) { /* if not ">&-" */ if (memory[redir->ndup.dupfd]) memory[fd] = 1; else { if (dup2(redir->ndup.dupfd, fd) < 0) error("%d: %s", redir->ndup.dupfd, strerror(errno)); } } else { close(fd); } return; case NHERE: case NXHERE: f = openhere(redir); break; default: abort(); } if (f != fd) { if (dup2(f, fd) == -1) { e = errno; close(f); error("%d: %s", fd, strerror(e)); } close(f); } } /* * Handle here documents. Normally we fork off a process to write the * data to a pipe. If the document is short, we can stuff the data in * the pipe without forking. */ static int openhere(union node *redir) { const char *p; int pip[2]; size_t len = 0; int flags; ssize_t written = 0; if (pipe(pip) < 0) error("Pipe call failed: %s", strerror(errno)); if (redir->type == NXHERE) p = redir->nhere.expdoc; else p = redir->nhere.doc->narg.text; len = strlen(p); if (len == 0) goto out; flags = fcntl(pip[1], F_GETFL, 0); if (flags != -1 && fcntl(pip[1], F_SETFL, flags | O_NONBLOCK) != -1) { written = write(pip[1], p, len); if (written < 0) written = 0; if ((size_t)written == len) goto out; fcntl(pip[1], F_SETFL, flags); } if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) { close(pip[0]); signal(SIGINT, SIG_IGN); signal(SIGQUIT, SIG_IGN); signal(SIGHUP, SIG_IGN); signal(SIGTSTP, SIG_IGN); signal(SIGPIPE, SIG_DFL); xwrite(pip[1], p + written, len - written); _exit(0); } out: close(pip[1]); return pip[0]; } /* * Undo the effects of the last redirection. */ void popredir(void) { struct redirtab *rp = redirlist; int i; INTOFF; if (empty_redirs > 0) { empty_redirs--; INTON; return; } for (i = 0 ; i < 10 ; i++) { if (rp->renamed[i] != EMPTY) { if (rp->renamed[i] >= 0) { dup2(rp->renamed[i], i); close(rp->renamed[i]); } else { close(i); } } } fd0_redirected = rp->fd0_redirected; empty_redirs = rp->empty_redirs; redirlist = rp->next; ckfree(rp); INTON; } /* Return true if fd 0 has already been redirected at least once. */ int fd0_redirected_p(void) { return fd0_redirected != 0; } /* * Discard all saved file descriptors. */ void clearredir(void) { struct redirtab *rp; int i; for (rp = redirlist ; rp ; rp = rp->next) { for (i = 0 ; i < 10 ; i++) { if (rp->renamed[i] >= 0) { close(rp->renamed[i]); } rp->renamed[i] = EMPTY; } } }