Firstly, *keep no change* for `hash_get()` with NULL
`alloc_func`.
Only focus on cases with non-NULL `alloc_func` of
`hash_get()`.
Since `hash_get()` with non-NULL `alloc_func` parameter
shall not fail, just ignore the returned value of it.
The returned value must not be NULL.
So in this case, remove the unnecessary checking NULL
or not for the returned value and add `void` in front
of it.
Importantly, also *keep no change* for the two cases with
non-NULL `alloc_func` -
1) Use `assert(<returned_data> == <searching_data>)` to
ensure it is a created node, not a found node.
Refer to `isis_vertex_queue_insert()` of isisd, there
are many examples of this case in isid.
2) Use `<returned_data> != <searching_data>` to judge it
is a found node, then free <searching_data>.
Refer to `aspath_intern()` of bgpd, there are many
examples of this case in bgpd.
Here, <returned_data> is the returned value from `hash_get()`,
and <searching_data> is the data, which is to be put into
hash table.
Signed-off-by: anlan_cs <vic.lan@pica8.com>
The script entries were being stored in a hash lookup with
the script name a pre-defined array of characters. The hash
lookup is succeeding since it is auto-installed at script
start time irrelevant if there is a handler function.
Modify the code so that if the scriptname is an empty
string "\0" just return a NULL so that zebra does
not attempt to actually load up the script
Signed-off-by: Donald Sharp <sharpd@nvidia.com>
Previous:
- frrscript_load: push Lua function onto stack
- frrscript_call: calls Lua function
Now:
- frrscript_load: checks Lua function
- frrscript_call: pushes and calls Lua function (first clear the stack)
So now we just need one frrscript_load for consecutive frrscript_call.
frrscript_call does not recompile or reload the script file, it just
keys it from the global Lua table (where it should already be).
Signed-off-by: Donald Lee <dlqs@gmx.com>
frrscript_load now loads a function instead of a file, so frrscript_unload
should be renamed since it does not unload a function.
Signed-off-by: Donald Lee <dlqs@gmx.com>
There is some rather heavy error checking logic in frrscript_call. Normally
I'd put this in the _frrscript_call function, but the error checking needs
to happen before the encoders/decoders in the macro are called.
The error checking looks messy but its really just nested ternary
expressions insite a larger statement expression.
Signed-off-by: Donald Lee <dlqs@gmx.com>
Instead of 1 frrscript : 1 lua state, it is changed to 1 : N.
The states are hashed with their function names.
Signed-off-by: Donald Lee <dlqs@gmx.com>
gcc-10 is complaining:
lib/frrscript.c:42:14: error: cast between incompatible function types from ‘const char * (*)(lua_State *, const char *)’ to ‘void (*)(lua_State *, const void *)’ [-Werror=cast-function-type]
42 | .encoder = (encoder_func)lua_pushstring,
| ^
Wrapper it to make it happy. Not sure what else to do.
Signed-off-by: Donald Sharp <sharpd@nvidia.com>
fname is MAXPATHLEN and scriptdir and fs->name are less then
MAXPATHLEN but the combination of those two + the `.lua` are
greater than the MAXPATHLEN. Just give us more room to prevent
a coding boo boo.
Signed-off-by: Donald Sharp <sharpd@nvidia.com>
Specify default via --with-scriptdir at compile time, override default
with --scriptdir at runtime. If unspecified, it's {sysconfdir}/scripts
(usually /etc/frr/scripts)
Signed-off-by: Quentin Young <qlyoung@nvidia.com>
This implements the ability to get results out from lua scripts after
they've run.
For each C type we support passing to Lua, there is a corresponding
`struct frrscript_codec`. This struct contains a typename field - just a
string identifying the type - and two function pointers. The first
function pointer, encode, takes a lua_State and a pointer to the C value
and pushes some corresponding Lua representation onto the stack. The
second, decode, assumes there is some Lua value on the stack and decodes
it into the corresponding C value.
Each supported type's `struct frrscript_codec` is registered with the
scripting stuff in the library, which creates a mapping between the type
name (string) and the `struct frrscript_codec`. When calling a script,
you specify arguments by passing an array of `struct frrscript_env`.
Each of these structs has a void *, a type name, and a desired binding
name. The type names are used to look up the appropriate function to
encode the pointed-at value onto the Lua stack, then bind the pushed
value to the provided binding name, so that the converted value is
accessible by that name within the script.
Results work in a similar way. After a script runs, call
frrscript_get_result() with the script and a `struct frrscript_env`.
The typename and name fields are used to fetch the Lua value from the
script's environment and use the registered decoder for the typename to
convert the Lua value back into a C value, which is returned from the
function. The caller is responsible for freeing these.
frrscript_call()'s macro foo has been stripped, as the underlying
function now takes fixed arrays. varargs have awful performance
characteristics, they're hard to read, and structs are more defined than
an order sensitive list.
Signed-off-by: Quentin Young <qlyoung@nvidia.com>
Add:
- log.warn()
- log.error()
- log.notice()
- log.info()
- log.debug()
to the global namespace for each script
Signed-off-by: Quentin Young <qlyoung@nvidia.com>
Rather than let Luaisms propagate from the start, this is some generic
wrapper stuff that defines some semantics for interacting with scripts
that aren't specific to the underlying language.
The concept I have in mind for FRR's idea of a script is:
- has a name
- has some inputs, which have types
- has some outputs, which have types
I don't want to even say they have to be files; maybe we can embed
scripts in frr.conf, for example. Similarly the types of inputs and
outputs are probably going to end up being some language-specific setup.
For now, we will stick to this simple model, but the plan is to add full
object support (ie calling back into C).
This shouldn't be misconstrued as prepping for multilingual scripting
support, which is a bad idea for the following reasons:
- Each language would require different FFI methods, and specifically
different object encoders; a lot of code
- Languages have different capabilities that would have to be brought to
parity with each other; a lot of work
- Languages have *vastly* different performance characteristics; bad
impressions, lots of issues we can't do anything about
- Each language would need a dedicated maintainer for the above reasons;
pragmatically difficult
- Supporting multiple languages fractures the community and limits the
audience with which a given script can be shared
The only pro for multilingual support would be ease of use for users not
familiar with Lua but familiar with one of the other supported
languages. This is not enough to outweigh the cons.
In order to get rich scripting capabilities, we need to be able to pass
representations of internal objects to the scripts. For example, a
script that performs some computation based on information about a peer
needs access to some equivalent of `struct peer` for the peer in
question. To transfer these objects from C-space into Lua-space we need
to encode them onto the Lua stack. This patch adds a mapping from
arbitrary type names to the functions that encode objects of that type.
For example, the function that encodes `struct peer` into a Lua table
could be registered with:
bgp_peer_encoder_func(struct frrscript *fs, struct peer *peer)
{
// encode peer to Lua table, push to stack in fs->scriptinfo->L
}
frrscript_register_type_encoder("peer", bgp_peer_encoder_func);
Later on when calling a script that wants a peer, the plan is to be able
to specify the type name like so:
frrscript_call(script, "peer", peer);
Using C-style types for the type names would have been nice, it might be
possible to do this with preprocessor magic or possibly python
preprocessing later on.
Signed-off-by: Quentin Young <qlyoung@nvidia.com>
mergeme no stdlib
Signed-off-by: Quentin Young <qlyoung@nvidia.com>
