text: /*
   * 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_compression_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_finish(ina) != ARCHIVE_OK)
  		die("Error closing input archive");
  	if (archive_write_finish(outa) != ARCHIVE_OK)
  		die("Error closing output archive");
  	return (0);
  }
  