OLD | NEW |
(Empty) | |
| 1 =pod |
| 2 |
| 3 =head1 NAME |
| 4 |
| 5 CMS_compress - create a CMS CompressedData structure |
| 6 |
| 7 =head1 SYNOPSIS |
| 8 |
| 9 #include <openssl/cms.h> |
| 10 |
| 11 CMS_ContentInfo *CMS_compress(BIO *in, int comp_nid, unsigned int flags); |
| 12 |
| 13 =head1 DESCRIPTION |
| 14 |
| 15 CMS_compress() creates and returns a CMS CompressedData structure. B<comp_nid> |
| 16 is the compression algorithm to use or B<NID_undef> to use the default |
| 17 algorithm (zlib compression). B<in> is the content to be compressed. |
| 18 B<flags> is an optional set of flags. |
| 19 |
| 20 =head1 NOTES |
| 21 |
| 22 The only currently supported compression algorithm is zlib using the NID |
| 23 NID_zlib_compression. |
| 24 |
| 25 If zlib support is not compiled into OpenSSL then CMS_compress() will return |
| 26 an error. |
| 27 |
| 28 If the B<CMS_TEXT> flag is set MIME headers for type B<text/plain> are |
| 29 prepended to the data. |
| 30 |
| 31 Normally the supplied content is translated into MIME canonical format (as |
| 32 required by the S/MIME specifications) if B<CMS_BINARY> is set no translation |
| 33 occurs. This option should be used if the supplied data is in binary format |
| 34 otherwise the translation will corrupt it. If B<CMS_BINARY> is set then |
| 35 B<CMS_TEXT> is ignored. |
| 36 |
| 37 If the B<CMS_STREAM> flag is set a partial B<CMS_ContentInfo> structure is |
| 38 returned suitable for streaming I/O: no data is read from the BIO B<in>. |
| 39 |
| 40 The compressed data is included in the CMS_ContentInfo structure, unless |
| 41 B<CMS_DETACHED> is set in which case it is omitted. This is rarely used in |
| 42 practice and is not supported by SMIME_write_CMS(). |
| 43 |
| 44 =head1 NOTES |
| 45 |
| 46 If the flag B<CMS_STREAM> is set the returned B<CMS_ContentInfo> structure is |
| 47 B<not> complete and outputting its contents via a function that does not |
| 48 properly finalize the B<CMS_ContentInfo> structure will give unpredictable |
| 49 results. |
| 50 |
| 51 Several functions including SMIME_write_CMS(), i2d_CMS_bio_stream(), |
| 52 PEM_write_bio_CMS_stream() finalize the structure. Alternatively finalization |
| 53 can be performed by obtaining the streaming ASN1 B<BIO> directly using |
| 54 BIO_new_CMS(). |
| 55 |
| 56 Additional compression parameters such as the zlib compression level cannot |
| 57 currently be set. |
| 58 |
| 59 =head1 RETURN VALUES |
| 60 |
| 61 CMS_compress() returns either a CMS_ContentInfo structure or NULL if an error |
| 62 occurred. The error can be obtained from ERR_get_error(3). |
| 63 |
| 64 =head1 SEE ALSO |
| 65 |
| 66 L<ERR_get_error(3)|ERR_get_error(3)>, L<CMS_uncompress(3)|CMS_uncompress(3)> |
| 67 |
| 68 =head1 HISTORY |
| 69 |
| 70 CMS_compress() was added to OpenSSL 0.9.8 |
| 71 The B<CMS_STREAM> flag was first supported in OpenSSL 1.0.0. |
| 72 |
| 73 =cut |
OLD | NEW |