Now file names become:
string[filename]
with a possibility of using other string features:
stringnoz[filename]
string[filename, CONST_SIZE]
and filename is left as type alias as it is commonly used:
type filename string[filename]
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.
Large overhaul moves syscalls and arg types from sys to prog.
Sys package now depends on prog and contains only generated
descriptions of syscalls.
Introduce prog.Target type that encapsulates all targer properties,
like syscall list, ptr/page size, etc. Also moves OS-dependent pieces
like mmap call generation from prog to sys.
Update #191
ptr64 is like ptr, but always takes 8 bytes of space.
Needed for some APIs. Unfortunately, most of these APIs
use buffer type, so we can't use ptr64 immidiately.
