text: /* Simple S/MIME compress example */
  #include <openssl/pem.h>
  #include <openssl/cms.h>
  #include <openssl/err.h>
  
  int main(int argc, char **argv)
  {
      BIO *in = NULL, *out = NULL;
      CMS_ContentInfo *cms = NULL;
      int ret = 1;
  
      /*
       * On OpenSSL 1.0.0+ only:
       * for streaming set CMS_STREAM
       */
      int flags = CMS_STREAM;
  
      OpenSSL_add_all_algorithms();
      ERR_load_crypto_strings();
  
      /* Open content being compressed */
  
      in = BIO_new_file("comp.txt", "r");
  
      if (!in)
          goto err;
  
      /* compress content */
      cms = CMS_compress(in, NID_zlib_compression, flags);
  
      if (!cms)
          goto err;
  
      out = BIO_new_file("smcomp.txt", "w");
      if (!out)
          goto err;
  
      /* Write out S/MIME message */
      if (!SMIME_write_CMS(out, cms, in, flags))
          goto err;
  
      ret = 0;
  
   err:
  
      if (ret) {
          fprintf(stderr, "Error Compressing Data\n");
          ERR_print_errors_fp(stderr);
      }
  
      if (cms)
          CMS_ContentInfo_free(cms);
      if (in)
          BIO_free(in);
      if (out)
          BIO_free(out);
  
      return ret;
  
  }
  