This change adds compiler support for complex path
expressions in len targets. E.g. it allows to refer
to a sibling field as len[parent_struct:field:another_field].
See the docs change for details.
This is just a compiler change.
The feature is not yet supported by the prog package.
This prepared for handling of bytesize[parent:foo:bar] expressions
by allowing multiple identifiers after colon.
No functional changes for now, just preparation for storing more
than one identifier after colon.
After generating syscall description for fidl files using fidlgen, prune
all unused structs using the exact same mechanism used by the compiler's
check for unused structs. This allows the FIDL compiler to support
modular compilation; it does not need to have global knowledge of
whether each struct is used or not.
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.
