Standard preamble:
========================================================================
..
.... Set up some character translations and predefined strings. \*(-- will
give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
double quote, and \*(R" will give a right double quote. \*(C+ will
give a nicer C++. Capital omega is used to do unbreakable dashes and
therefore won't be available. \*(C` and \*(C' expand to `' in nroff,
nothing in troff, for use with C<>.
.tr \(*W- . ds -- \(*W- . ds PI pi . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch . ds L" "" . ds R" "" . ds C` "" . ds C' "" 'br\} . ds -- \|\(em\| . ds PI \(*p . ds L" `` . ds R" '' . ds C` . ds C' 'br\}
Escape single quotes in literal strings from groff's Unicode transform.
If the F register is >0, we'll generate index entries on stderr for
titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
entries marked with X<> in POD. Of course, you'll have to process the
output yourself in some meaningful fashion.
Avoid warning from groff about undefined register 'F'.
.. .nr rF 0 . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF
Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
Fear. Run. Save yourself. No user-serviceable parts.
. \" fudge factors for nroff and troff . ds #H 0 . ds #V .8m . ds #F .3m . ds #[ \f1 . ds #] .\} . ds #H ((1u-(\\\\n(.fu%2u))*.13m) . ds #V .6m . ds #F 0 . ds #[ \& . ds #] \& .\} . \" simple accents for nroff and troff . ds ' \& . ds ` \& . ds ^ \& . ds , \& . ds ~ ~ . ds / .\} . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' .\} . \" troff and (daisy-wheel) nroff accents . \" corrections for vroff . \" for low resolution devices (crt and lpr) \{\ . ds : e . ds 8 ss . ds o a . ds d- d\h'-1'\(ga . ds D- D\h'-1'\(hy . ds th \o'bp' . ds Th \o'LP' . ds ae ae . ds Ae AE .\} ========================================================================
Title "CRYPTO_GET_EX_NEW_INDEX 3"
way too many mistakes in technical documents.
.Vb 10 APP BIO DH DRBG DSA EC_KEY ENGINE RSA SSL SSL_CTX SSL_SESSION UI UI_METHOD X509 X509_STORE X509_STORE_CTX .Ve
Each is identified by an CRYPTO_EX_INDEX_xxx define in the crypto.h header file. In addition, \s-1CRYPTO_EX_INDEX_APP\s0 is reserved for applications to use this facility for their own structures.
The \s-1API\s0 described here is used by OpenSSL to manipulate exdata for specific structures. Since the application data can be anything at all it is passed and retrieved as a void * type.
The \s-1CRYPTO_EX_DATA\s0 type is opaque. To initialize the exdata part of a structure, call CRYPTO_new_ex_data(). This is only necessary for \fB\s-1CRYPTO_EX_INDEX_APP\s0 objects.
Exdata types are identified by an index, an integer guaranteed to be unique within structures for the lifetime of the program. Applications using exdata typically call CRYPTO_get_ex_new_index at startup, and store the result in a global variable, or write a wrapper function to provide lazy evaluation. The class_index should be one of the \fBCRYPTO_EX_INDEX_xxx values. The argl and argp parameters are saved to be passed to the callbacks but are otherwise not used. In order to transparently manipulate exdata, three callbacks must be provided. The semantics of those callbacks are described below.
When copying or releasing objects with exdata, the callback functions are called in increasing order of their index value.
If a dynamic library can be unloaded, it should call CRYPTO_free_ex_index() when this is done. This will replace the callbacks with no-ops so that applications don't crash. Any existing exdata will be leaked.
To set or get the exdata on an object, the appropriate type-specific routine must be used. This is because the containing structure is opaque and the \s-1CRYPTO_EX_DATA\s0 field is not accessible. In both \s-1API\s0's, the \fBidx parameter should be an already-created index value.
When setting exdata, the pointer specified with a particular index is saved, and returned on a subsequent \*(L"get\*(R" call. If the application is going to release the data, it must make sure to set a \s-1NULL\s0 value at the index, to avoid likely double-free crashes.
The function CRYPTO_free_ex_data is used to free all exdata attached to a structure. The appropriate type-specific routine must be used. The class_index identifies the structure type, the obj is a pointer to the actual structure, and r is a pointer to the structure's exdata field.
When a structure is initially allocated (such as RSA_new()) then the \fBnew_func() is called for every defined index. There is no requirement that the entire parent, or containing, structure has been set up. The new_func() is typically used only to allocate memory to store the exdata, and perhaps an \*(L"initialized\*(R" flag within that memory. The exdata value should be set by calling CRYPTO_set_ex_data().
When a structure is free'd (such as SSL_CTX_free()) then the \fBfree_func() is called for every defined index. Again, the state of the parent structure is not guaranteed. The free_func() may be called with a \s-1NULL\s0 pointer.
Both new_func() and free_func() take the same parameters. The parent is the pointer to the structure that contains the exdata. The ptr is the current exdata item; for new_func() this will typically be \s-1NULL.\s0 The r parameter is a pointer to the exdata field of the object. The idx is the index and is the value returned when the callbacks were initially registered via CRYPTO_get_ex_new_index() and can be used if the same callback handles different types of exdata.
\fBdup_func() is called when a structure is being copied. This is only done for \s-1SSL\s0, \s-1SSL_SESSION\s0, \s-1EC_KEY\s0 objects and \s-1BIO\s0 chains via \fBBIO_dup_chain(). The to and from parameters are pointers to the destination and source \s-1CRYPTO_EX_DATA\s0 structures, respectively. The from_d parameter needs to be cast to a void **pptr as the \s-1API\s0 has currently the wrong signature; that will be changed in a future version. The *pptr is a pointer to the source exdata. When the dup_func() returns, the value in *pptr is copied to the destination ex_data. If the pointer contained in *pptr is not modified by the dup_func(), then both to and from will point to the same data. The idx, argl and argp parameters are as described for the other two callbacks. If the dup_func() returns 0 the whole CRYPTO_dup_ex_data() will fail.
\fBCRYPTO_free_ex_index() and \fBCRYPTO_set_ex_data() return 1 on success or 0 on failure.
\fBCRYPTO_get_ex_data() returns the application data or \s-1NULL\s0 on failure; note that \s-1NULL\s0 may be a valid value.
\fBdup_func() should return 0 for failure and 1 for success.
Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.