Index: openssl/doc/crypto/CMS_compress.pod |
=================================================================== |
--- openssl/doc/crypto/CMS_compress.pod (revision 0) |
+++ openssl/doc/crypto/CMS_compress.pod (revision 0) |
@@ -0,0 +1,73 @@ |
+=pod |
+ |
+=head1 NAME |
+ |
+CMS_compress - create a CMS CompressedData structure |
+ |
+=head1 SYNOPSIS |
+ |
+ #include <openssl/cms.h> |
+ |
+ CMS_ContentInfo *CMS_compress(BIO *in, int comp_nid, unsigned int flags); |
+ |
+=head1 DESCRIPTION |
+ |
+CMS_compress() creates and returns a CMS CompressedData structure. B<comp_nid> |
+is the compression algorithm to use or B<NID_undef> to use the default |
+algorithm (zlib compression). B<in> is the content to be compressed. |
+B<flags> is an optional set of flags. |
+ |
+=head1 NOTES |
+ |
+The only currently supported compression algorithm is zlib using the NID |
+NID_zlib_compression. |
+ |
+If zlib support is not compiled into OpenSSL then CMS_compress() will return |
+an error. |
+ |
+If the B<CMS_TEXT> flag is set MIME headers for type B<text/plain> are |
+prepended to the data. |
+ |
+Normally the supplied content is translated into MIME canonical format (as |
+required by the S/MIME specifications) if B<CMS_BINARY> is set no translation |
+occurs. This option should be used if the supplied data is in binary format |
+otherwise the translation will corrupt it. If B<CMS_BINARY> is set then |
+B<CMS_TEXT> is ignored. |
+ |
+If the B<CMS_STREAM> flag is set a partial B<CMS_ContentInfo> structure is |
+returned suitable for streaming I/O: no data is read from the BIO B<in>. |
+ |
+The compressed data is included in the CMS_ContentInfo structure, unless |
+B<CMS_DETACHED> is set in which case it is omitted. This is rarely used in |
+practice and is not supported by SMIME_write_CMS(). |
+ |
+=head1 NOTES |
+ |
+If the flag B<CMS_STREAM> is set the returned B<CMS_ContentInfo> structure is |
+B<not> complete and outputting its contents via a function that does not |
+properly finalize the B<CMS_ContentInfo> structure will give unpredictable |
+results. |
+ |
+Several functions including SMIME_write_CMS(), i2d_CMS_bio_stream(), |
+PEM_write_bio_CMS_stream() finalize the structure. Alternatively finalization |
+can be performed by obtaining the streaming ASN1 B<BIO> directly using |
+BIO_new_CMS(). |
+ |
+Additional compression parameters such as the zlib compression level cannot |
+currently be set. |
+ |
+=head1 RETURN VALUES |
+ |
+CMS_compress() returns either a CMS_ContentInfo structure or NULL if an error |
+occurred. The error can be obtained from ERR_get_error(3). |
+ |
+=head1 SEE ALSO |
+ |
+L<ERR_get_error(3)|ERR_get_error(3)>, L<CMS_uncompress(3)|CMS_uncompress(3)> |
+ |
+=head1 HISTORY |
+ |
+CMS_compress() was added to OpenSSL 0.9.8 |
+The B<CMS_STREAM> flag was first supported in OpenSSL 1.0.0. |
+ |
+=cut |