Netlink descriptions contain tons of code duplication,
and need much more for proper descriptions. Introduce
type templates to simplify writing such descriptions
and remove code duplication.
Note: type templates are experimental, have poor error handling
and are subject to change.
Type templates can be declared as follows:
```
type buffer[DIR] ptr[DIR, array[int8]]
type fileoff[BASE] BASE
type nlattr[TYPE, PAYLOAD] {
nla_len len[parent, int16]
nla_type const[TYPE, int16]
payload PAYLOAD
} [align_4]
```
and later used as follows:
```
syscall(a buffer[in], b fileoff[int64], c ptr[in, nlattr[FOO, int32]])
```
This adds builtin:
type bool8 int8[0:1]
type bool16 int16[0:1]
type bool32 int32[0:1]
type bool64 int64[0:1]
type boolptr intptr[0:1]
We used to use just int's for bools.
But bool types provide several advantages:
- make true/false probability equal
- improve description expressiveness
- reduce search space (we will take advantage of this later)
Complex types that are often repeated can be given short type aliases using the
following syntax:
```
type identifier underlying_type
```
For example:
```
type signalno int32[0:65]
type net_port proc[20000, 4, int16be]
```
Then, type alias can be used instead of the underlying type in any contexts.
Underlying type needs to be described as if it's a struct field, that is,
with the base type if it's required. However, type alias can be used as syscall
arguments as well. Underlying types are currently restricted to integer types,
`ptr`, `ptr64`, `const`, `flags` and `proc` types.
The old parser in sys/sysparser is too hacky, difficult to extend
and drops debug info too early, so that we can't produce proper error messages.
Add a new parser that is build like a proper language parser
and preserves full debug info for every token.
