added some more examples

oss-internship-2020/sapi_libarchive/CMakeLists.txt

@@ -0,0 +1,48 @@
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+cmake_minimum_required(VERSION 3.16)
+
+project(libarchive_sapi CXX)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED 17)
+
+# Build SAPI library
+set(SAPI_ROOT "/usr/local/google/home/amedar/internship/sandboxed-api" CACHE PATH "Path to the Sandboxed API source tree")
+
+add_subdirectory("${SAPI_ROOT}"
+  "${CMAKE_BINARY_DIR}/sandboxed-api-build"
+  EXCLUDE_FROM_ALL
+)
+
+add_sapi_library(
+  libarchive_sapi
+  
+  FUNCTIONS
+  archive_read_new
+  
+  INPUTS libarchive/libarchive/archive.h
+  LIBRARY archive
+  LIBRARY_NAME Libarchive
+  NAMESPACE ""
+)
+
+target_include_directories(libarchive_sapi INTERFACE
+  "${PROJECT_BINARY_DIR}"  # To find the generated SAPI header
+)
+
+
+add_subdirectory(libarchive)
+add_subdirectory(examples)

oss-internship-2020/sapi_libarchive/examples/CMakeLists.txt

@@ -0,0 +1,40 @@
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# small example - todo delete later
+add_executable(small_example
+    small_example.cc
+)
+
+target_link_libraries(small_example PRIVATE
+    archive
+)
+
+add_executable(sapi_example
+    sapi_example.cc
+)
+
+target_link_libraries(sapi_example PRIVATE
+    libarchive_sapi
+    sapi::sapi
+    glog::glog
+)
+
+add_executable(untar
+    untar.cc
+)
+
+target_link_libraries(untar PRIVATE
+    archive
+)

oss-internship-2020/sapi_libarchive/examples/minitar.cc

@@ -0,0 +1,478 @@
+/*-
+ * This file is in the public domain.
+ * Do with it as you will.
+ */
+
+/*-
+ * This is a compact "tar" program whose primary goal is small size.
+ * Statically linked, it can be very small indeed.  This serves a number
+ * of goals:
+ *   o a testbed for libarchive (to check for link pollution),
+ *   o a useful tool for space-constrained systems (boot floppies, etc),
+ *   o a place to experiment with new implementation ideas for bsdtar,
+ *   o a small program to demonstrate libarchive usage.
+ *
+ * Use the following macros to suppress features:
+ *   NO_BZIP2 - Implies NO_BZIP2_CREATE and NO_BZIP2_EXTRACT
+ *   NO_BZIP2_CREATE - Suppress bzip2 compression support.
+ *   NO_BZIP2_EXTRACT - Suppress bzip2 auto-detection and decompression.
+ *   NO_COMPRESS - Implies NO_COMPRESS_CREATE and NO_COMPRESS_EXTRACT
+ *   NO_COMPRESS_CREATE - Suppress compress(1) compression support
+ *   NO_COMPRESS_EXTRACT - Suppress compress(1) auto-detect and decompression.
+ *   NO_CREATE - Suppress all archive creation support.
+ *   NO_CPIO_EXTRACT - Suppress auto-detect and dearchiving of cpio archives.
+ *   NO_GZIP - Implies NO_GZIP_CREATE and NO_GZIP_EXTRACT
+ *   NO_GZIP_CREATE - Suppress gzip compression support.
+ *   NO_GZIP_EXTRACT - Suppress gzip auto-detection and decompression.
+ *   NO_LOOKUP - Try to avoid getpw/getgr routines, which can be very large
+ *   NO_TAR_EXTRACT - Suppress tar extraction
+ *
+ * With all of the above macros defined (except NO_TAR_EXTRACT), you
+ * get a very small program that can recognize and extract essentially
+ * any uncompressed tar archive.  On FreeBSD 5.1, this minimal program
+ * is under 64k, statically linked, which compares rather favorably to
+ *         main(){printf("hello, world");}
+ * which is over 60k statically linked on the same operating system.
+ * Without any of the above macros, you get a static executable of
+ * about 180k with a lot of very sophisticated modern features.
+ * Obviously, it's trivial to add support for ISO, Zip, mtree,
+ * lzma/xz, etc.  Just fill in the appropriate setup calls.
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <archive.h>
+#include <archive_entry.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <iostream>
+
+/*
+ * NO_CREATE implies NO_BZIP2_CREATE and NO_GZIP_CREATE and NO_COMPRESS_CREATE.
+ */
+#ifdef NO_CREATE
+#undef NO_BZIP2_CREATE
+#define NO_BZIP2_CREATE
+#undef NO_COMPRESS_CREATE
+#define	NO_COMPRESS_CREATE
+#undef NO_GZIP_CREATE
+#define NO_GZIP_CREATE
+#endif
+
+/*
+ * The combination of NO_BZIP2_CREATE and NO_BZIP2_EXTRACT is
+ * equivalent to NO_BZIP2.
+ */
+#ifdef NO_BZIP2_CREATE
+#ifdef NO_BZIP2_EXTRACT
+#undef NO_BZIP2
+#define NO_BZIP2
+#endif
+#endif
+
+#ifdef NO_BZIP2
+#undef NO_BZIP2_EXTRACT
+#define NO_BZIP2_EXTRACT
+#undef NO_BZIP2_CREATE
+#define NO_BZIP2_CREATE
+#endif
+
+/*
+ * The combination of NO_COMPRESS_CREATE and NO_COMPRESS_EXTRACT is
+ * equivalent to NO_COMPRESS.
+ */
+#ifdef NO_COMPRESS_CREATE
+#ifdef NO_COMPRESS_EXTRACT
+#undef NO_COMPRESS
+#define NO_COMPRESS
+#endif
+#endif
+
+#ifdef NO_COMPRESS
+#undef NO_COMPRESS_EXTRACT
+#define NO_COMPRESS_EXTRACT
+#undef NO_COMPRESS_CREATE
+#define NO_COMPRESS_CREATE
+#endif
+
+/*
+ * The combination of NO_GZIP_CREATE and NO_GZIP_EXTRACT is
+ * equivalent to NO_GZIP.
+ */
+#ifdef NO_GZIP_CREATE
+#ifdef NO_GZIP_EXTRACT
+#undef NO_GZIP
+#define NO_GZIP
+#endif
+#endif
+
+#ifdef NO_GZIP
+#undef NO_GZIP_EXTRACT
+#define NO_GZIP_EXTRACT
+#undef NO_GZIP_CREATE
+#define NO_GZIP_CREATE
+#endif
+
+#ifndef NO_CREATE
+static void	create(const char *filename, int compress, const char **argv);
+#endif
+static void	errmsg(const char *);
+static void	extract(const char *filename, int do_extract, int flags);
+static int	copy_data(struct archive *, struct archive *);
+static void	msg(const char *);
+static void	usage(void);
+
+static int verbose = 0;
+
+int
+main(int argc, const char **argv)
+{
+    std::cout << "BEGIN\n";
+	const char *filename = NULL;
+	int compress, flags, mode, opt;
+
+	(void)argc;
+	mode = 'x';
+	verbose = 0;
+	compress = '\0';
+	flags = ARCHIVE_EXTRACT_TIME;
+
+	/* Among other sins, getopt(3) pulls in printf(3). */
+	while (*++argv != NULL && **argv == '-') {
+		const char *p = *argv + 1;
+
+		while ((opt = *p++) != '\0') {
+			switch (opt) {
+#ifndef NO_CREATE
+			case 'c':
+				mode = opt;
+				break;
+#endif
+			case 'f':
+				if (*p != '\0')
+					filename = p;
+				else
+					filename = *++argv;
+				p += strlen(p);
+				break;
+#ifndef NO_BZIP2_CREATE
+			case 'j':
+				compress = opt;
+				break;
+#endif
+			case 'p':
+				flags |= ARCHIVE_EXTRACT_PERM;
+				flags |= ARCHIVE_EXTRACT_ACL;
+				flags |= ARCHIVE_EXTRACT_FFLAGS;
+				break;
+			case 't':
+				mode = opt;
+				break;
+			case 'v':
+				verbose++;
+				break;
+			case 'x':
+				mode = opt;
+				break;
+#ifndef NO_BZIP2_CREATE
+			case 'y':
+				compress = opt;
+				break;
+#endif
+#ifndef NO_COMPRESS_CREATE
+			case 'Z':
+				compress = opt;
+				break;
+#endif
+#ifndef NO_GZIP_CREATE
+			case 'z':
+				compress = opt;
+				break;
+#endif
+			default:
+				usage();
+			}
+		}
+	}
+
+	switch (mode) {
+#ifndef NO_CREATE
+	case 'c':
+		create(filename, compress, argv);
+		break;
+#endif
+	case 't':
+		extract(filename, 0, flags);
+		break;
+	case 'x':
+		extract(filename, 1, flags);
+		break;
+	}
+
+	return (0);
+}
+
+
+#ifndef NO_CREATE
+static char buff[16384];
+
+static void
+create(const char *filename, int compress, const char **argv)
+{
+
+    std::cout << "CREATE FILENAME=" << filename << std::endl;
+	struct archive *a;
+	struct archive_entry *entry;
+	ssize_t len;
+	int fd;
+
+	a = archive_write_new();
+	switch (compress) {
+#ifndef NO_BZIP2_CREATE
+	case 'j': case 'y':
+		archive_write_add_filter_bzip2(a);
+		break;
+#endif
+#ifndef NO_COMPRESS_CREATE
+	case 'Z':
+		archive_write_add_filter_compress(a);
+		break;
+#endif
+#ifndef NO_GZIP_CREATE
+	case 'z':
+		archive_write_add_filter_gzip(a);
+		break;
+#endif
+	default:
+		archive_write_add_filter_none(a);
+		break;
+	}
+	archive_write_set_format_ustar(a);
+	if (filename != NULL && strcmp(filename, "-") == 0)
+		filename = NULL;
+	archive_write_open_filename(a, filename);
+
+	while (*argv != NULL) {
+        std::cout << "handling file = " << *argv << std::endl;
+		struct archive *disk = archive_read_disk_new();
+#ifndef NO_LOOKUP
+		archive_read_disk_set_standard_lookup(disk);
+#endif
+		int r;
+
+		r = archive_read_disk_open(disk, *argv);
+		if (r != ARCHIVE_OK) {
+			errmsg(archive_error_string(disk));
+			errmsg("\n");
+			exit(1);
+		}
+
+		for (;;) {
+			int needcr = 0;
+
+			entry = archive_entry_new();
+			r = archive_read_next_header2(disk, entry);
+			if (r == ARCHIVE_EOF)
+				break;
+			if (r != ARCHIVE_OK) {
+				errmsg(archive_error_string(disk));
+				errmsg("\n");
+				exit(1);
+			}
+			archive_read_disk_descend(disk);
+			if (verbose) {
+				msg("a ");
+				msg(archive_entry_pathname(entry));
+				needcr = 1;
+			}
+			r = archive_write_header(a, entry);
+			if (r < ARCHIVE_OK) {
+                std::cout << " --- error here, code = " << r << " --- " << std::endl;
+				errmsg(": ");
+				errmsg(archive_error_string(a));
+				needcr = 1;
+			}
+			if (r == ARCHIVE_FATAL)
+				exit(1);
+			if (r > ARCHIVE_FAILED) {
+#if 0
+				/* Ideally, we would be able to use
+				 * the same code to copy a body from
+				 * an archive_read_disk to an
+				 * archive_write that we use for
+				 * copying data from an archive_read
+				 * to an archive_write_disk.
+				 * Unfortunately, this doesn't quite
+				 * work yet. */
+				copy_data(disk, a);
+#else
+				/* For now, we use a simpler loop to copy data
+				 * into the target archive. */
+				fd = open(archive_entry_sourcepath(entry), O_RDONLY);
+				len = read(fd, buff, sizeof(buff));
+				while (len > 0) {
+					archive_write_data(a, buff, len);
+					len = read(fd, buff, sizeof(buff));
+				}
+				close(fd);
+#endif
+			}
+			archive_entry_free(entry);
+			if (needcr)
+				msg("\n");
+		}
+		archive_read_close(disk);
+		archive_read_free(disk);
+		argv++;
+	}
+	archive_write_close(a);
+	archive_write_free(a);
+}
+#endif
+
+static void
+extract(const char *filename, int do_extract, int flags)
+{
+
+	struct archive *a;
+	struct archive *ext;
+	struct archive_entry *entry;
+	int r;
+
+	a = archive_read_new();
+	ext = archive_write_disk_new();
+	archive_write_disk_set_options(ext, flags);
+#ifndef NO_BZIP2_EXTRACT
+	archive_read_support_filter_bzip2(a);
+#endif
+#ifndef NO_GZIP_EXTRACT
+	archive_read_support_filter_gzip(a);
+#endif
+#ifndef NO_COMPRESS_EXTRACT
+	archive_read_support_filter_compress(a);
+#endif
+#ifndef NO_TAR_EXTRACT
+	archive_read_support_format_tar(a);
+#endif
+#ifndef NO_CPIO_EXTRACT
+	archive_read_support_format_cpio(a);
+#endif
+#ifndef NO_LOOKUP
+	archive_write_disk_set_standard_lookup(ext);
+#endif
+	if (filename != NULL && strcmp(filename, "-") == 0)
+		filename = NULL;
+	if ((r = archive_read_open_filename(a, filename, 10240))) {
+		errmsg(archive_error_string(a));
+		errmsg("\n");
+		exit(r);
+	}
+	for (;;) {
+		int needcr = 0;
+		r = archive_read_next_header(a, &entry);
+		if (r == ARCHIVE_EOF)
+			break;
+		if (r != ARCHIVE_OK) {
+			errmsg(archive_error_string(a));
+			errmsg("\n");
+			exit(1);
+		}
+		if (verbose && do_extract)
+			msg("x ");
+		if (verbose || !do_extract) {
+			msg(archive_entry_pathname(entry));
+			msg(" ");
+			needcr = 1;
+		}
+		if (do_extract) {
+			r = archive_write_header(ext, entry);
+			if (r != ARCHIVE_OK) {
+				errmsg(archive_error_string(a));
+				needcr = 1;
+			}
+			else {
+				r = copy_data(a, ext);
+				if (r != ARCHIVE_OK)
+					needcr = 1;
+			}
+		}
+		if (needcr)
+			msg("\n");
+	}
+	archive_read_close(a);
+	archive_read_free(a);
+
+	archive_write_close(ext);
+  	archive_write_free(ext);
+	exit(0);
+}
+
+static int
+copy_data(struct archive *ar, struct archive *aw)
+{
+	int r;
+	const void *buff;
+	size_t size;
+	int64_t offset;
+
+	for (;;) {
+		r = archive_read_data_block(ar, &buff, &size, &offset);
+		if (r == ARCHIVE_EOF)
+			return (ARCHIVE_OK);
+		if (r != ARCHIVE_OK) {
+			errmsg(archive_error_string(ar));
+			return (r);
+		}
+		r = archive_write_data_block(aw, buff, size, offset);
+		if (r != ARCHIVE_OK) {
+			errmsg(archive_error_string(ar));
+			return (r);
+		}
+	}
+}
+
+static void
+msg(const char *m)
+{
+	write(1, m, strlen(m));
+}
+
+static void
+errmsg(const char *m)
+{
+	if (m == NULL) {
+		m = "Error: No error description provided.\n";
+	}
+	write(2, m, strlen(m));
+}
+
+static void
+usage(void)
+{
+/* Many program options depend on compile options. */
+	const char *m = "Usage: minitar [-"
+#ifndef NO_CREATE
+	    "c"
+#endif
+#ifndef	NO_BZIP2
+	    "j"
+#endif
+	    "tvx"
+#ifndef NO_BZIP2
+	    "y"
+#endif
+#ifndef NO_COMPRESS
+	    "Z"
+#endif
+#ifndef NO_GZIP
+	    "z"
+#endif
+	    "] [-f file] [file]\n";
+
+	errmsg(m);
+	exit(1);
+}

oss-internship-2020/sapi_libarchive/examples/sapi_example.cc

@@ -0,0 +1,8 @@
+#include <iostream>
+#include "libarchive_sapi.sapi.h"
+
+
+int main() {
+    std::cout << "WORKS2" << std::endl;
+    return 0;
+}

oss-internship-2020/sapi_libarchive/examples/small_example.cc

@@ -0,0 +1,9 @@
+#include <iostream>
+
+#include <archive.h>
+#include <archive_entry.h>
+
+int main() {
+    std::cout << "WORKS" << std::endl;
+    return 0;
+}

oss-internship-2020/sapi_libarchive/examples/tarfilter.cc

@@ -0,0 +1,113 @@
+/*
+ * This file is in the public domain.
+ *
+ * Feel free to use it as you wish.
+ */
+
+/*
+ * This example program reads an archive from stdin (which can be in
+ * any format recognized by libarchive) and writes certain entries to
+ * an uncompressed ustar archive on stdout.  This is a template for
+ * many kinds of archive manipulation: converting formats, resetting
+ * ownership, inserting entries, removing entries, etc.
+ *
+ * To compile:
+ * gcc -Wall -o tarfilter tarfilter.c -larchive -lz -lbz2
+ */
+
+#include <sys/stat.h>
+#include <archive.h>
+#include <archive_entry.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+static void
+die(char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+	fprintf(stderr, "\n");
+	exit(1);
+}
+
+int
+main(int argc, char **argv)
+{
+	char buff[8192];
+	ssize_t len;
+	int r;
+	mode_t m;
+	struct archive *ina;
+	struct archive *outa;
+	struct archive_entry *entry;
+
+	/* Read an archive from stdin, with automatic format detection. */
+	ina = archive_read_new();
+	if (ina == NULL)
+		die("Couldn't create archive reader.");
+	if (archive_read_support_filter_all(ina) != ARCHIVE_OK)
+		die("Couldn't enable decompression");
+	if (archive_read_support_format_all(ina) != ARCHIVE_OK)
+		die("Couldn't enable read formats");
+	if (archive_read_open_fd(ina, 0, 10240) != ARCHIVE_OK)
+		die("Couldn't open input archive");
+
+	/* Write an uncompressed ustar archive to stdout. */
+	outa = archive_write_new();
+	if (outa == NULL)
+		die("Couldn't create archive writer.");
+	if (archive_write_set_compression_none(outa) != ARCHIVE_OK)
+		die("Couldn't enable compression");
+	if (archive_write_set_format_ustar(outa) != ARCHIVE_OK)
+		die("Couldn't set output format");
+	if (archive_write_open_fd(outa, 1) != ARCHIVE_OK)
+		die("Couldn't open output archive");
+
+	/* Examine each entry in the input archive. */
+	while ((r = archive_read_next_header(ina, &entry)) == ARCHIVE_OK) {
+		fprintf(stderr, "%s: ", archive_entry_pathname(entry));
+
+		/* Skip anything that isn't a regular file. */
+		if (!S_ISREG(archive_entry_mode(entry))) {
+			fprintf(stderr, "skipped\n");
+			continue;
+		}
+
+		/* Make everything owned by root/wheel. */
+		archive_entry_set_uid(entry, 0);
+		archive_entry_set_uname(entry, "root");
+		archive_entry_set_gid(entry, 0);
+		archive_entry_set_gname(entry, "wheel");
+
+		/* Make everything permission 0744, strip SUID, etc. */
+		m = archive_entry_mode(entry);
+		archive_entry_set_mode(entry, (m & ~07777) | 0744);
+
+		/* Copy input entries to output archive. */
+		if (archive_write_header(outa, entry) != ARCHIVE_OK)
+			die("Error writing output archive");
+		if (archive_entry_size(entry) > 0) {
+			len = archive_read_data(ina, buff, sizeof(buff));
+			while (len > 0) {
+				if (archive_write_data(outa, buff, len) != len)
+					die("Error writing output archive");
+				len = archive_read_data(ina, buff, sizeof(buff));
+			}
+			if (len < 0)
+				die("Error reading input archive");
+		}
+		fprintf(stderr, "copied\n");
+	}
+	if (r != ARCHIVE_EOF)
+		die("Error reading archive");
+	/* Close the archives.  */
+	if (archive_read_free(ina) != ARCHIVE_OK)
+		die("Error closing input archive");
+	if (archive_write_free(outa) != ARCHIVE_OK)
+		die("Error closing output archive");
+	return (0);
+}

oss-internship-2020/sapi_libarchive/examples/untar.cc

@@ -0,0 +1,277 @@
+/*
+ * This file is in the public domain.
+ * Use it as you wish.
+ */
+
+/*
+ * This is a compact tar extraction program using libarchive whose
+ * primary goal is small executable size.  Statically linked, it can
+ * be very small, depending in large part on how cleanly factored your
+ * system libraries are.  Note that this uses the standard libarchive,
+ * without any special recompilation.  The only functional concession
+ * is that this program uses the uid/gid from the archive instead of
+ * doing uname/gname lookups.  (Add a call to
+ * archive_write_disk_set_standard_lookup() to enable uname/gname
+ * lookups, but be aware that this can add 500k or more to a static
+ * executable, depending on the system libraries, since user/group
+ * lookups frequently pull in password, YP/LDAP, networking, and DNS
+ * resolver libraries.)
+ *
+ * To build:
+ * $ gcc -static -Wall -o untar untar.c -larchive
+ * $ strip untar
+ *
+ * NOTE: On some systems, you may need to add additional flags
+ * to ensure that untar.c is compiled the same way as libarchive
+ * was compiled.  In particular, Linux users will probably
+ * have to add -D_FILE_OFFSET_BITS=64 to the command line above.
+ *
+ * For fun, statically compile the following simple hello.c program
+ * using the same flags as for untar and compare the size:
+ *
+ * #include <stdio.h>
+ * int main(int argc, char **argv) {
+ *    printf("hello, world\n");
+ *    return(0);
+ * }
+ *
+ * You may be even more surprised by the compiled size of true.c listed here:
+ *
+ * int main(int argc, char **argv) {
+ *    return (0);
+ * }
+ *
+ * On a slightly customized FreeBSD 5 system that I used around
+ * 2005, hello above compiled to 89k compared to untar of 69k.  So at
+ * that time, libarchive's tar reader and extract-to-disk routines
+ * compiled to less code than printf().
+ *
+ * On my FreeBSD development system today (August, 2009):
+ *  hello: 195024 bytes
+ *  true: 194912 bytes
+ *  untar: 259924 bytes
+ */
+
+#include <iostream>
+#include <sys/types.h>
+
+#include <sys/stat.h>
+
+#include <archive.h>
+#include <archive_entry.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static void	errmsg(const char *);
+static void	extract(const char *filename, int do_extract, int flags);
+static void	fail(const char *, const char *, int);
+static int	copy_data(struct archive *, struct archive *);
+static void	msg(const char *);
+static void	usage(void);
+static void	warn(const char *, const char *);
+
+static int verbose = 0;
+
+int
+main(int argc, const char **argv)
+{
+	const char *filename = NULL;
+	int compress, flags, mode, opt;
+
+	(void)argc;
+	mode = 'x';
+	verbose = 0;
+	compress = '\0';
+	flags = ARCHIVE_EXTRACT_TIME;
+
+	/* Among other sins, getopt(3) pulls in printf(3). */
+	while (*++argv != NULL && **argv == '-') {
+		const char *p = *argv + 1;
+
+		while ((opt = *p++) != '\0') {
+			switch (opt) {
+			case 'f':
+				if (*p != '\0')
+					filename = p;
+				else
+					filename = *++argv;
+				p += strlen(p);
+				break;
+			case 'p':
+				flags |= ARCHIVE_EXTRACT_PERM;
+				flags |= ARCHIVE_EXTRACT_ACL;
+				flags |= ARCHIVE_EXTRACT_FFLAGS;
+				break;
+			case 't':
+				mode = opt;
+				break;
+			case 'v':
+				verbose++;
+				break;
+			case 'x':
+				mode = opt;
+				break;
+			default:
+				usage();
+			}
+		}
+	}
+
+    std::cout << "begin\n";
+
+	switch (mode) {
+	case 't':
+		extract(filename, 0, flags);
+		break;
+	case 'x':
+		extract(filename, 1, flags);
+		break;
+	}
+
+    std::cout << "end";
+
+	return (0);
+}
+
+
+static void
+extract(const char *filename, int do_extract, int flags)
+{
+	struct archive *a;
+	struct archive *ext;
+	struct archive_entry *entry;
+	int r;
+
+	a = archive_read_new();
+	ext = archive_write_disk_new();
+	archive_write_disk_set_options(ext, flags);
+	/*
+	 * Note: archive_write_disk_set_standard_lookup() is useful
+	 * here, but it requires library routines that can add 500k or
+	 * more to a static executable.
+	 */
+	archive_read_support_format_tar(a);
+	/*
+	 * On my system, enabling other archive formats adds 20k-30k
+	 * each.  Enabling gzip decompression adds about 20k.
+	 * Enabling bzip2 is more expensive because the libbz2 library
+	 * isn't very well factored.
+	 */
+
+    std::cout <<"AAA\n";
+	if (filename != NULL && strcmp(filename, "-") == 0)
+		filename = NULL;
+	if ((r = archive_read_open_filename(a, filename, 10240)))
+		fail("archive_read_open_filename()",
+		    archive_error_string(a), r);
+
+    std::cout << "BBB\n";
+	for (;;) {
+		r = archive_read_next_header(a, &entry);
+		if (r == ARCHIVE_EOF)
+			break;
+		if (r != ARCHIVE_OK)
+			fail("archive_read_next_header()",
+			    archive_error_string(a), 1);
+		if (verbose && do_extract)
+			msg("x ");
+		if (verbose || !do_extract)
+			msg(archive_entry_pathname(entry));
+		if (do_extract) {
+			r = archive_write_header(ext, entry);
+			if (r != ARCHIVE_OK)
+				warn("archive_write_header()",
+				    archive_error_string(ext));
+			else {
+				copy_data(a, ext);
+				r = archive_write_finish_entry(ext);
+				if (r != ARCHIVE_OK)
+					fail("archive_write_finish_entry()",
+					    archive_error_string(ext), 1);
+			}
+
+		}
+		if (verbose || !do_extract)
+			msg("\n");
+	}
+	archive_read_close(a);
+	archive_read_free(a);
+	
+	archive_write_close(ext);
+  	archive_write_free(ext);
+	exit(0);
+}
+
+static int
+copy_data(struct archive *ar, struct archive *aw)
+{
+	int r;
+	const void *buff;
+	size_t size;
+#if ARCHIVE_VERSION_NUMBER >= 3000000
+	int64_t offset;
+#else
+	off_t offset;
+#endif
+
+	for (;;) {
+		r = archive_read_data_block(ar, &buff, &size, &offset);
+		if (r == ARCHIVE_EOF)
+			return (ARCHIVE_OK);
+		if (r != ARCHIVE_OK)
+			return (r);
+		r = archive_write_data_block(aw, buff, size, offset);
+		if (r != ARCHIVE_OK) {
+			warn("archive_write_data_block()",
+			    archive_error_string(aw));
+			return (r);
+		}
+	}
+}
+
+/*
+ * These reporting functions use low-level I/O; on some systems, this
+ * is a significant code reduction.  Of course, on many server and
+ * desktop operating systems, malloc() and even crt rely on printf(),
+ * which in turn pulls in most of the rest of stdio, so this is not an
+ * optimization at all there.  (If you're going to pay 100k or more
+ * for printf() anyway, you may as well use it!)
+ */
+static void
+msg(const char *m)
+{
+	write(1, m, strlen(m));
+}
+
+static void
+errmsg(const char *m)
+{
+	write(2, m, strlen(m));
+}
+
+static void
+warn(const char *f, const char *m)
+{
+	errmsg(f);
+	errmsg(" failed: ");
+	errmsg(m);
+	errmsg("\n");
+}
+
+static void
+fail(const char *f, const char *m, int r)
+{
+	warn(f, m);
+	exit(r);
+}
+
+static void
+usage(void)
+{
+	const char *m = "Usage: untar [-tvx] [-f file] [file]\n";
+	errmsg(m);
+	exit(1);
+}