sandboxed-api/oss-internship-2020/libarchive/ld_preload_example/minitar_main.cc

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2020-10-09 21:52:17 +08:00
// 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.
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// clang-format off
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/*-
* 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 "minitar.h" // NOLINT(build/include)
/*
* 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
int main(int unused_argc, const char** argv) {
const char* filename = nullptr;
int compress;
int flags;
int mode;
int opt;
mode = 'x';
int verbose = 0;
compress = '\0';
flags = ARCHIVE_EXTRACT_TIME;
/* Among other sins, getopt(3) pulls in printf(3). */
while (*++argv != nullptr && **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, verbose);
break;
#endif
case 't':
extract(filename, 0, flags, verbose);
break;
case 'x':
extract(filename, 1, flags, verbose);
break;
}
return (0);
}
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// clang-format on