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| -rw-r--r-- | README.md | 69 |
1 files changed, 56 insertions, 13 deletions
@@ -4,24 +4,67 @@ Currently available routines: - ERR helpers - OpenSSL's ERR functions do not lend themselves very well to - provider's own error tables, because they can't pass the - provider's handle to the error record building routines. - This is due to certain limitations with the base C standard - requirements for OpenSSL itself (C90). - + OpenSSL's ERR functions do not lend themselves very well to provider's + own error tables, because they can't pass the provider's handle to the + error record building routines. This is due to certain limitations with + the base C standard requirements for OpenSSL itself (C90). + These helpers are replacements of OpenSSL's ERR_raise() and - ERR_raise_data() that take better advantage of more modern C + `ERR_raise_data()` that take better advantage of more modern C standards. C99 required. - See the comments in include/prov/err.h for more information. + See the comments in `include/prov/err.h` for more information. - NUM helper - Converting OSSL_PARAM numbers to native numbers present a bit of a + Converting `OSSL_PARAM` numbers to native numbers present a bit of a challenge, as they are variable length, and may need some adaption to fit into native numbers. - - provnum_get() and provnum_set() claim to be universally applicable - functions for converting an OSSL_PARAM number to a native integer - or + + `provnum_get()` and `provnum_set()` claim to be universally applicable + functions for converting an OSSL_PARAM number to a native integer or + bignum implementations. + +- `OSSL_PARAM` parsing helper + + Parsing `OSSL_PARAM` keys can be done in many ways, with various + performance problems. A simple (even naïve) way was to loop over the + params and `strcasecmp()` them with known names. Depending on the + `strcasecmp()` implementation, that can be rather slow. + + `perl/gen_param_LL.pl` takes a specification in form of a perl ARRAY, + which contains a C function name (for example, `"parse_params"`) as + first item, followed by a series of tuples of this form: + + ``` perl + NAME => "key" + ``` + + Each such `NAME` becomes a couple of C macros: + + - `S_NAME`, with the `"key"` string as its value. + - `V_NAME`, with a unique generated integer as its value. + + The function name that's given at the start of the function becomes a C + function that is called with a single argument, the key to parse. As a + test, the following should always be true: + + ``` C + parse_params(S_NAME) == V_NAME + ``` + + When looking through an `OSSL_PARAM` array, the easy way is to do + something like this: + + ``` C + const OSSL_PARAM *p; + + for (p = params; p->key != NULL; p++) { + switch (parse_params(p->key)) { + case V_NAME: + /* Do whatever's needed */ + break; + ... + } + } + ``` |