cat.c

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kevin Fall.
 *
 * 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 <sys/capsicum.h>
#include <sys/param.h>
#include <sys/stat.h>
#ifndef NO_UDOM_SUPPORT
#include <sys/socket.h>
#include <sys/un.h>
#include <netdb.h>
#endif

#include <capsicum_helpers.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <wchar.h>
#include <wctype.h>

#include <libcasper.h>
#include <casper/cap_fileargs.h>
#include <casper/cap_net.h>

static int bflag, eflag, lflag, nflag, sflag, tflag, vflag;
static int rval;
static const char *filename;
static fileargs_t *fa;

static void usage(void) __dead2;
static void scanfiles(char *argv[], int cooked);
#ifndef BOOTSTRAP_CAT
static void cook_cat(FILE *);
static ssize_t in_kernel_copy(int);
#endif
static void raw_cat(int);

#ifndef NO_UDOM_SUPPORT
static cap_channel_t *capnet;

static int udom_open(const char *path, int flags);
#endif

/*
 * Memory strategy threshold, in pages: if physmem is larger than this,
 * use a large buffer.
 */
#define	PHYSPAGES_THRESHOLD (32 * 1024)

/* Maximum buffer size in bytes - do not allow it to grow larger than this. */
#define	BUFSIZE_MAX (2 * 1024 * 1024)

/*
 * Small (default) buffer size in bytes. It's inefficient for this to be
 * smaller than MAXPHYS.
 */
#define	BUFSIZE_SMALL (MAXPHYS)


/*
 * For the bootstrapped cat binary (needed for locked appending to METALOG), we
 * disable all flags except -l and -u to avoid non-portable function calls.
 * In the future we may instead want to write a small portable bootstrap tool
 * that locks the output file before writing to it. However, for now
 * bootstrapping cat without multibyte support is the simpler solution.
 */
#ifdef BOOTSTRAP_CAT
#define SUPPORTED_FLAGS "lu"
#else
#define SUPPORTED_FLAGS "belnstuv"
#endif

#ifndef NO_UDOM_SUPPORT
static void
init_casper_net(cap_channel_t *casper)
{
	cap_net_limit_t *limit;
	int familylimit;

	capnet = cap_service_open(casper, "system.net");
	if (capnet == NULL)
		err(EXIT_FAILURE, "unable to create network service");

	limit = cap_net_limit_init(capnet, CAPNET_NAME2ADDR |
	    CAPNET_CONNECTDNS);
	if (limit == NULL)
		err(EXIT_FAILURE, "unable to create limits");

	familylimit = AF_LOCAL;
	cap_net_limit_name2addr_family(limit, &familylimit, 1);

	if (cap_net_limit(limit) != 0)
		err(EXIT_FAILURE, "unable to apply limits");
}
#endif

static void
init_casper(int argc, char *argv[])
{
	cap_channel_t *casper;
	cap_rights_t rights;

	casper = cap_init();
	if (casper == NULL)
		err(EXIT_FAILURE, "unable to create Casper");

	fa = fileargs_cinit(casper, argc, argv, O_RDONLY, 0,
	    cap_rights_init(&rights, CAP_READ, CAP_FSTAT, CAP_FCNTL, CAP_SEEK),
	    FA_OPEN | FA_REALPATH);
	if (fa == NULL)
		err(EXIT_FAILURE, "unable to create fileargs");

#ifndef NO_UDOM_SUPPORT
	init_casper_net(casper);
#endif

	cap_close(casper);
}

int
main(int argc, char *argv[])
{
	int ch;
	struct flock stdout_lock;

	setlocale(LC_CTYPE, "");

	while ((ch = getopt(argc, argv, SUPPORTED_FLAGS)) != -1)
		switch (ch) {
		case 'b':
			bflag = nflag = 1;	/* -b implies -n */
			break;
		case 'e':
			eflag = vflag = 1;	/* -e implies -v */
			break;
		case 'l':
			lflag = 1;
			break;
		case 'n':
			nflag = 1;
			break;
		case 's':
			sflag = 1;
			break;
		case 't':
			tflag = vflag = 1;	/* -t implies -v */
			break;
		case 'u':
			setbuf(stdout, NULL);
			break;
		case 'v':
			vflag = 1;
			break;
		default:
			usage();
		}
	argv += optind;
	argc -= optind;

	if (lflag) {
		stdout_lock.l_len = 0;
		stdout_lock.l_start = 0;
		stdout_lock.l_type = F_WRLCK;
		stdout_lock.l_whence = SEEK_SET;
		if (fcntl(STDOUT_FILENO, F_SETLKW, &stdout_lock) != 0)
			err(EXIT_FAILURE, "stdout");
	}

	init_casper(argc, argv);

	caph_cache_catpages();

	if (caph_enter_casper() != 0)
		err(EXIT_FAILURE, "capsicum");

	if (bflag || eflag || nflag || sflag || tflag || vflag)
		scanfiles(argv, 1);
	else
		scanfiles(argv, 0);
	if (fclose(stdout))
		err(1, "stdout");
	exit(rval);
	/* NOTREACHED */
}

static void
usage(void)
{

	fprintf(stderr, "usage: cat [-" SUPPORTED_FLAGS "] [file ...]\n");
	exit(1);
	/* NOTREACHED */
}

static void
scanfiles(char *argv[], int cooked __unused)
{
	int fd, i;
	char *path;
#ifndef BOOTSTRAP_CAT
	FILE *fp;
#endif

	i = 0;
	fd = -1;
	while ((path = argv[i]) != NULL || i == 0) {
		if (path == NULL || strcmp(path, "-") == 0) {
			filename = "stdin";
			fd = STDIN_FILENO;
		} else {
			filename = path;
			fd = fileargs_open(fa, path);
#ifndef NO_UDOM_SUPPORT
			if (fd < 0 && errno == EOPNOTSUPP)
				fd = udom_open(path, O_RDONLY);
#endif
		}
		if (fd < 0) {
			warn("%s", path);
			rval = 1;
#ifndef BOOTSTRAP_CAT
		} else if (cooked) {
			if (fd == STDIN_FILENO)
				cook_cat(stdin);
			else {
				fp = fdopen(fd, "r");
				cook_cat(fp);
				fclose(fp);
			}
#endif
		} else {
#ifndef BOOTSTRAP_CAT
			if (in_kernel_copy(fd) != 0) {
				if (errno == EINVAL || errno == EBADF ||
				    errno == EISDIR)
					raw_cat(fd);
				else
					err(1, "%s", filename);
			}
#else
			raw_cat(fd);
#endif
			if (fd != STDIN_FILENO)
				close(fd);
		}
		if (path == NULL)
			break;
		++i;
	}
}

#ifndef BOOTSTRAP_CAT
static void
cook_cat(FILE *fp)
{
	int ch, gobble, line, prev;
	wint_t wch;

	/* Reset EOF condition on stdin. */
	if (fp == stdin && feof(stdin))
		clearerr(stdin);

	line = gobble = 0;
	for (prev = '\n'; (ch = getc(fp)) != EOF; prev = ch) {
		if (prev == '\n') {
			if (sflag) {
				if (ch == '\n') {
					if (gobble)
						continue;
					gobble = 1;
				} else
					gobble = 0;
			}
			if (nflag) {
				if (!bflag || ch != '\n') {
					(void)fprintf(stdout, "%6d\t", ++line);
					if (ferror(stdout))
						break;
				} else if (eflag) {
					(void)fprintf(stdout, "%6s\t", "");
					if (ferror(stdout))
						break;
				}
			}
		}
		if (ch == '\n') {
			if (eflag && putchar('$') == EOF)
				break;
		} else if (ch == '\t') {
			if (tflag) {
				if (putchar('^') == EOF || putchar('I') == EOF)
					break;
				continue;
			}
		} else if (vflag) {
			(void)ungetc(ch, fp);
			/*
			 * Our getwc(3) doesn't change file position
			 * on error.
			 */
			if ((wch = getwc(fp)) == WEOF) {
				if (ferror(fp) && errno == EILSEQ) {
					clearerr(fp);
					/* Resync attempt. */
					memset(&fp->_mbstate, 0, sizeof(mbstate_t));
					if ((ch = getc(fp)) == EOF)
						break;
					wch = ch;
					goto ilseq;
				} else
					break;
			}
			if (!iswascii(wch) && !iswprint(wch)) {
ilseq:
				if (putchar('M') == EOF || putchar('-') == EOF)
					break;
				wch = toascii(wch);
			}
			if (iswcntrl(wch)) {
				ch = toascii(wch);
				ch = (ch == '\177') ? '?' : (ch | 0100);
				if (putchar('^') == EOF || putchar(ch) == EOF)
					break;
				continue;
			}
			if (putwchar(wch) == WEOF)
				break;
			ch = -1;
			continue;
		}
		if (putchar(ch) == EOF)
			break;
	}
	if (ferror(fp)) {
		warn("%s", filename);
		rval = 1;
		clearerr(fp);
	}
	if (ferror(stdout))
		err(1, "stdout");
}

static ssize_t
in_kernel_copy(int rfd)
{
	int wfd;
	ssize_t ret;

	wfd = fileno(stdout);
	ret = 1;

	while (ret > 0)
		ret = copy_file_range(rfd, NULL, wfd, NULL, SSIZE_MAX, 0);

	return (ret);
}
#endif /* BOOTSTRAP_CAT */

static void
raw_cat(int rfd)
{
	long pagesize;
	int off, wfd;
	ssize_t nr, nw;
	static size_t bsize;
	static char *buf = NULL;
	struct stat sbuf;

	wfd = fileno(stdout);
	if (buf == NULL) {
		if (fstat(wfd, &sbuf))
			err(1, "stdout");
		if (S_ISREG(sbuf.st_mode)) {
			/* If there's plenty of RAM, use a large copy buffer */
			if (sysconf(_SC_PHYS_PAGES) > PHYSPAGES_THRESHOLD)
				bsize = MIN(BUFSIZE_MAX, MAXPHYS * 8);
			else
				bsize = BUFSIZE_SMALL;
		} else {
			bsize = sbuf.st_blksize;
			pagesize = sysconf(_SC_PAGESIZE);
			if (pagesize > 0)
				bsize = MAX(bsize, (size_t)pagesize);
		}
		if ((buf = malloc(bsize)) == NULL)
			err(1, "malloc() failure of IO buffer");
	}
	while ((nr = read(rfd, buf, bsize)) > 0)
		for (off = 0; nr; nr -= nw, off += nw)
			if ((nw = write(wfd, buf + off, (size_t)nr)) < 0)
				err(1, "stdout");
	if (nr < 0) {
		warn("%s", filename);
		rval = 1;
	}
}

#ifndef NO_UDOM_SUPPORT

static int
udom_open(const char *path, int flags)
{
	struct addrinfo hints, *res, *res0;
	char rpath[PATH_MAX];
	int error, fd, serrno;
	cap_rights_t rights;

	/*
	 * Construct the unix domain socket address and attempt to connect.
	 */
	bzero(&hints, sizeof(hints));
	hints.ai_family = AF_LOCAL;

	if (fileargs_realpath(fa, path, rpath) == NULL)
		return (-1);

	error = cap_getaddrinfo(capnet, rpath, NULL, &hints, &res0);
	if (error) {
		warn("%s", gai_strerror(error));
		errno = EINVAL;
		return (-1);
	}
	cap_rights_init(&rights, CAP_CONNECT, CAP_READ, CAP_WRITE,
	    CAP_SHUTDOWN, CAP_FSTAT, CAP_FCNTL);

	/* Default error if something goes wrong. */
	serrno = EINVAL;

	for (res = res0; res != NULL; res = res->ai_next) {
		fd = socket(res->ai_family, res->ai_socktype,
		    res->ai_protocol);
		if (fd < 0) {
			serrno = errno;
			freeaddrinfo(res0);
			errno = serrno;
			return (-1);
		}
		if (caph_rights_limit(fd, &rights) != 0) {
			serrno = errno;
			close(fd);
			freeaddrinfo(res0);
			errno = serrno;
			return (-1);
		}
		error = cap_connect(capnet, fd, res->ai_addr, res->ai_addrlen);
		if (error == 0)
			break;
		else {
			serrno = errno;
			close(fd);
		}
	}
	freeaddrinfo(res0);

	if (res == NULL) {
		errno = serrno;
		return (-1);
	}

	/*
	 * handle the open flags by shutting down appropriate directions
	 */

	switch (flags & O_ACCMODE) {
	case O_RDONLY:
		cap_rights_clear(&rights, CAP_WRITE);
		if (shutdown(fd, SHUT_WR) != 0)
			warn(NULL);
		break;
	case O_WRONLY:
		cap_rights_clear(&rights, CAP_READ);
		if (shutdown(fd, SHUT_RD) != 0)
			warn(NULL);
		break;
	default:
		break;
	}

	cap_rights_clear(&rights, CAP_CONNECT, CAP_SHUTDOWN);
	if (caph_rights_limit(fd, &rights) != 0) {
		serrno = errno;
		close(fd);
		errno = serrno;
		return (-1);
	}
	return (fd);
}

#endif