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binary.py
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binary.py
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import io
import typing
from . import convention
from . import instruction
from . import leb128
from . import log
from . import num
# ======================================================================================================================
# Binary Format Types
# ======================================================================================================================
class ValueType(int):
# Value types are encoded by a single byte.
# valtype ::= {
# 0x7f: i32,
# 0x7e: i64,
# 0x7d: f32,
# 0x7c: f64,
# }
def __repr__(self):
return {
convention.i32: 'i32',
convention.i64: 'i64',
convention.f32: 'f32',
convention.f64: 'f64',
}[self]
@classmethod
def from_reader(cls, r: typing.BinaryIO):
return ValueType(ord(r.read(1)))
class ResultType:
# Result types classify the result of executing instructions or blocks, which is a sequence of values written with
# brackets.
#
# resulttype ::= [valtype?]
def __init__(self):
self.data: typing.List[ValueType] = []
def __repr__(self):
return f'result_type({self.data.__repr__()})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = ResultType()
n = leb128.u.decode_reader(r)[0]
o.data = [ValueType.from_reader(r) for i in range(n)]
return o
class FunctionType:
# Function types are encoded by the byte 0x60 followed by the respective vectors of parameter and result types.
#
# functype ::= 0x60 t1∗:vec(valtype) t2∗:vec(valtype) ⇒ [t1∗] → [t2∗]
def __init__(self):
self.args: ResultType = ResultType()
self.rets: ResultType = ResultType()
def __repr__(self):
return f'function_type({self.args}, {self.rets})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = FunctionType()
assert ord(r.read(1)) == convention.sign
o.args = ResultType.from_reader(r)
o.rets = ResultType.from_reader(r)
return o
class Limits:
# Limits are encoded with a preceding flag indicating whether a maximum is present.
#
# limits ::= 0x00 n:u32 ⇒ {min n,max ϵ}
# | 0x01 n:u32 m:u32 ⇒ {min n,max m}
def __init__(self):
self.n: int = 0
self.m: int = 0
def __repr__(self):
return f'limits({self.n}, {self.m})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = Limits()
flag = ord(r.read(1))
o.n = leb128.u.decode_reader(r)[0]
o.m = leb128.u.decode_reader(r)[0] if flag else 0x00
return o
class MemoryType:
# Memory types classify linear memories and their size range.
#
# memtype ::= limits
#
# The limits constrain the minimum and optionally the maximum size of a memory. The limits are given in units of
# page size.
def __init__(self):
self.limits: Limits = Limits()
def __repr__(self):
return f'memory_type({self.limits.__repr__()})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = MemoryType()
o.limits = Limits.from_reader(r)
return o
class ElementType(int):
# The element type funcref is the infinite union of all function types. A table of that type thus contains
# references to functions of heterogeneous type.
# In future versions of WebAssembly, additional element types may be introduced.
def __repr__(self):
return {
convention.funcref: 'funcref',
}[self]
@classmethod
def from_reader(cls, r: typing.BinaryIO):
return ElementType(ord(r.read(1)))
class TableType:
# Table types classify tables over elements of element types within a size range.
#
# tabletype ::= limits elemtype
# elemtype ::= funcref
#
# Like memories, tables are constrained by limits for their minimum and optionally maximum size. The limits are
# given in numbers of entries. The element type funcref is the infinite union of all function types. A table of that
# type thus contains references to functions of heterogeneous type.
def __init__(self):
self.element_type: ElementType = ElementType()
self.limits: Limits = Limits()
def __repr__(self):
return f'table_type({self.element_type}, {self.limits})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = TableType()
o.element_type = ElementType.from_reader(r)
o.limits = Limits.from_reader(r)
return o
class Mut(int):
# Mut const | var
def __repr__(self):
return {
convention.const: 'const',
convention.var: 'var',
}[self]
@classmethod
def from_reader(cls, r: typing.BinaryIO):
return Mut(ord(r.read(1)))
class GlobalType:
# Global types are encoded by their value type and a flag for their
# mutability.
#
# globaltype ::= t:valtype m:mut ⇒ m t
# mut ::= 0x00 ⇒ const
# | 0x01 ⇒ var
def __init__(self):
self.value_type: ValueType = ValueType()
self.mut: Mut = Mut()
def __repr__(self):
return f'global_type({self.mut} {self.value_type})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = GlobalType()
o.value_type = ValueType.from_reader(r)
o.mut = Mut.from_reader(r)
return o
ExternalType = typing.Union[FunctionType, TableType, MemoryType, GlobalType]
# ======================================================================================================================
# Binary Format Instructions
# ======================================================================================================================
class BlockType(int):
# Block types are encoded in special compressed form, by either the byte 0x40 indicating the empty type, as a
# single value type, or as a type index encoded as a positive signed integer.
#
# blocktype ::= 0x40
# | t: valtype
# | x: s33
def __repr__(self):
if self == convention.empty:
return 'empty'
return ValueType(self).__repr__()
@classmethod
def from_reader(cls, r: typing.BinaryIO):
return BlockType(ord(r.read(1)))
class Instruction:
# Instructions are encoded by opcodes. Each opcode is represented by a single byte, and is followed by the
# instruction's immediate arguments, where present. The only exception are structured control instructions, which
# consist of several opcodes bracketing their nested instruction sequences.
def __init__(self):
self.opcode: int = 0x00
self.args: typing.List[typing.Any] = []
def __repr__(self):
return f'{instruction.opcode[self.opcode][0]} {self.args}'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = Instruction()
o.opcode: int = ord(r.read(1))
o.args = []
if o.opcode in [
instruction.block,
instruction.loop,
instruction.if_,
]:
block_type = BlockType.from_reader(r)
o.args = [block_type]
return o
if o.opcode in [
instruction.br,
instruction.br_if,
]:
o.args = [LabelIndex(leb128.u.decode_reader(r)[0])]
return o
if o.opcode == instruction.br_table:
n = leb128.u.decode_reader(r)[0]
a = [LabelIndex(leb128.u.decode_reader(r)[0]) for _ in range(n)]
b = LabelIndex(leb128.u.decode_reader(r)[0])
o.args = [a, b]
return o
if o.opcode == instruction.call:
o.args = [FunctionIndex(leb128.u.decode_reader(r)[0])]
return o
if o.opcode == instruction.call_indirect:
i = TypeIndex(leb128.u.decode_reader(r)[0])
n = ord(r.read(1))
o.args = [i, n]
return o
if o.opcode in [
instruction.get_local,
instruction.set_local,
instruction.tee_local,
]:
o.args = [LocalIndex(leb128.u.decode_reader(r)[0])]
return o
if o.opcode in [
instruction.get_global,
instruction.set_global,
]:
o.args = [GlobalIndex(leb128.u.decode_reader(r)[0])]
return o
if o.opcode in [
instruction.i32_load,
instruction.i64_load,
instruction.f32_load,
instruction.f64_load,
instruction.i32_load8_s,
instruction.i32_load8_u,
instruction.i32_load16_s,
instruction.i32_load16_u,
instruction.i64_load8_s,
instruction.i64_load8_u,
instruction.i64_load16_s,
instruction.i64_load16_u,
instruction.i64_load32_s,
instruction.i64_load32_u,
instruction.i32_store,
instruction.i64_store,
instruction.f32_store,
instruction.f64_store,
instruction.i32_store8,
instruction.i32_store16,
instruction.i64_store8,
instruction.i64_store16,
instruction.i64_store32,
]:
o.args = [leb128.u.decode_reader(r)[0], leb128.u.decode_reader(r)[0]]
return o
if o.opcode in [
instruction.current_memory,
instruction.grow_memory
]:
n = ord(r.read(1))
o.args = [n]
return o
if o.opcode == instruction.i32_const:
o.args = [leb128.i.decode_reader(r)[0]]
return o
if o.opcode == instruction.i64_const:
o.args = [leb128.i.decode_reader(r)[0]]
return o
if o.opcode == instruction.f32_const:
# https://stackoverflow.com/questions/47961537/webassembly-f32-const-nan0x200000-means-0x7fa00000-or-0x7fe00000
# python misinterpret 0x7fa00000 as 0x7fe00000, when encapsulate as built-in float type.
o.args = [num.LittleEndian.i32(r.read(4))]
return o
if o.opcode == instruction.f64_const:
o.args = [num.LittleEndian.i64(r.read(8))]
return o
return o
# ======================================================================================================================
# Binary Format Modules
# ======================================================================================================================
class TypeIndex(int):
def __repr__(self):
return f'type_index({super().__repr__()})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
return TypeIndex(leb128.u.decode_reader(r)[0])
class FunctionIndex(int):
def __repr__(self):
return f'function_index({super().__repr__()})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
return FunctionIndex(leb128.u.decode_reader(r)[0])
class TableIndex(int):
def __repr__(self):
return f'table_index({super().__repr__()})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
return TableIndex(leb128.u.decode_reader(r)[0])
class MemoryIndex(int):
def __repr__(self):
return f'memory_index({super().__repr__()})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
return MemoryIndex(leb128.u.decode_reader(r)[0])
class GlobalIndex(int):
def __repr__(self):
return f'global_index({super().__repr__()})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
return GlobalIndex(leb128.u.decode_reader(r)[0])
class LocalIndex(int):
def __repr__(self):
return f'local_index({super().__repr__()})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
return LocalIndex(leb128.u.decode_reader(r)[0])
class LabelIndex(int):
def __repr__(self):
return f'label_index({super().__repr__()})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
return LabelIndex(leb128.u.decode_reader(r)[0])
class Custom:
# custom ::= name byte∗
def __init__(self):
self.name: str = ''
self.data: bytearray = bytearray()
def __repr__(self):
return f'custom({self.name})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = Custom()
n = leb128.u.decode_reader(r)[0]
o.name = r.read(n).decode()
o.data = bytearray(r.read(-1))
return o
class CustomSection:
# Custom sections have the id 0. They are intended to be used for debugging
# information or third-party extensions, and are ignored by the WebAssembly
# semantics. Their contents consist of a name further identifying the custom
# section, followed by an uninterpreted sequence of bytes for custom use.
#
# customsec ::= section0(custom)
# custom ::= name byte∗
def __init__(self):
self.custom: Custom = Custom()
def __repr__(self):
return f'custom_section({self.custom})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = CustomSection()
o.custom = Custom.from_reader(r)
return o
class TypeSection:
# The type section has the id 1. It decodes into a vector of function
# types that represent the types component of a module.
#
# typesec ::= ft∗:section1(vec(functype)) ⇒ ft∗
def __init__(self):
self.data: typing.List[FunctionType] = []
def __repr__(self):
return f'type_section({self.data})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = TypeSection()
n = leb128.u.decode_reader(r)[0]
o.data = [FunctionType.from_reader(r) for _ in range(n)]
return o
ImportDesc = typing.Union[TypeIndex, TableType, MemoryType, GlobalType]
class Import:
# The imports component of a module defines a set of imports that are required for instantiation.
#
# import ::= {module name, name name, desc importdesc}
# importdesc ::= func typeidx | table tabletype | mem memtype | global globaltype
#
# Each import is labeled by a two-level name space, consisting of a module name and a name for an entity within
# that module. Importable definitions are functions, tables, memories, and globals. Each import is specified by a
# descriptor with a respective type that a definition provided during instantiation is required to match. Every
# import defines an index in the respective index space. In each index space, the indices of imports go before the
# first index of any definition contained in the module itself.
def __init__(self):
self.module: str = ''
self.name: str = ''
self.desc: ImportDesc = 0x00
def __repr__(self):
return f'import({self.module}.{self.name}, {self.desc})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = Import()
n = leb128.u.decode_reader(r)[0]
o.module = r.read(n).decode()
n = leb128.u.decode_reader(r)[0]
o.name = r.read(n).decode()
n = ord(r.read(1))
o.desc = {
convention.extern_function: TypeIndex.from_reader,
convention.extern_table: TableType.from_reader,
convention.extern_memory: MemoryType.from_reader,
convention.extern_global: GlobalType.from_reader,
}[n](r)
return o
class ImportSection:
# The import section has the id 2. It decodes into a vector of imports
# that represent the imports component of a module.
#
# importsec ::= im∗:section2(vec(import)) ⇒ im∗
# import ::= mod:name nm:name d:importdesc ⇒ {module mod, name nm, desc d}
# importdesc ::= 0x00 x:typeidx ⇒ func x
# | 0x01 tt:tabletype ⇒ table tt
# | 0x02 mt:memtype ⇒ mem mt
# | 0x03 gt:globaltype ⇒ global gt
def __init__(self):
self.data: typing.List[Import] = []
def __repr__(self):
return f'import_section({self.data})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = ImportSection()
n = leb128.u.decode_reader(r)[0]
o.data = [Import.from_reader(r) for _ in range(n)]
return o
class FunctionSection:
# The function section has the id 3. It decodes into a vector of type
# indices that represent the type fields of the functions in the funcs
# component of a module. The locals and body fields of the respective
# functions are encoded separately in the code section.
#
# funcsec ::= x∗:section3(vec(typeidx)) ⇒ x∗
def __init__(self):
self.data: typing.List[TypeIndex] = []
def __repr__(self):
return f'function_section({self.data})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = FunctionSection()
n = leb128.u.decode_reader(r)[0]
o.data = [TypeIndex.from_reader(r) for _ in range(n)]
return o
class Table:
# The tables component of a module defines a vector of tables described by their table type:
#
# table ::= {type tabletype}
def __init__(self):
self.type: TableType = TableType()
def __repr__(self):
return f'table({self.type})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = Table()
o.type = TableType.from_reader(r)
return o
class TableSection:
# The table section has the id 4. It decodes into a vector of tables that
# represent the tables component of a module.
#
# tablesec ::= tab∗:section4(vec(table)) ⇒ tab∗
# table ::= tt:tabletype ⇒ {type tt}
def __init__(self):
self.data: typing.List[Table] = []
def __repr__(self):
return f'table_section({self.data})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = TableSection()
n = leb128.u.decode_reader(r)[0]
o.data = [Table.from_reader(r) for _ in range(n)]
return o
class Memory:
# The mems component of a module defines a vector of linear memories (or memories for short) as described by their
# memory type:
#
# mem ::= {type memtype}
def __init__(self):
self.type: MemoryType = MemoryType()
def __repr__(self):
return f'memory({self.type})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = Memory()
o.type = MemoryType.from_reader(r)
return o
class MemorySection:
# The memory section has the id 5. It decodes into a vector of memories
# that represent the mems component of a module.
#
# memsec ::= mem∗:section5(vec(mem)) ⇒ mem∗
# mem ::= mt:memtype ⇒ {type mt}
def __init__(self):
self.data: typing.List[Memory] = []
def __repr__(self):
return f'memory_section({self.data})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = MemorySection()
n = leb128.u.decode_reader(r)[0]
o.data = [Memory.from_reader(r) for _ in range(n)]
return o
class Expression:
# Function bodies, initialization values for globals, and offsets of element or data segments are given as
# expressions, which are sequences of instructions terminated by an end marker.
#
# expr ::= instr∗ 0x0B
#
# In some places, validation restricts expressions to be constant, which limits the set of allowable instructions.
def __init__(self):
self.data: typing.List[Instruction] = []
self.position: typing.Dict[int, typing.List[int]] = {}
def __repr__(self):
return f'expression({self.data})'
@classmethod
def mark(cls, data: typing.List[Instruction]) -> typing.Dict[int, typing.List[int]]:
position = {} # pc => { start, end, else }
stack = []
for i, e in enumerate(data):
if e.opcode in [instruction.block, instruction.loop, instruction.if_]:
stack.append([i])
continue
if e.opcode == instruction.else_:
stack[-1].append(i)
continue
if e.opcode == instruction.end:
if stack:
b = stack.pop()
b.insert(1, i)
for e in b:
position[e] = b
continue
if stack:
raise Exception('pywasm: expression ended in middle of body')
return position
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = Expression()
d = 1
while True:
i = Instruction.from_reader(r)
if not i:
break
o.data.append(i)
if i.opcode in [instruction.block, instruction.loop, instruction.if_]:
d += 1
if i.opcode == instruction.end:
d -= 1
if d == 0:
break
if o.data[-1].opcode != instruction.end:
raise Exception('pywasm: expression did not end with 0xb')
o.position = cls.mark(o.data)
return o
class Global:
# The globals component of a module defines a vector of global variables (or globals for short):
#
# global ::= {type globaltype, init expr}
def __init__(self):
self.type: GlobalType = GlobalType()
self.expr: Expression = Expression()
def __repr__(self):
return f'global({self.type}, {self.expr})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = Global()
o.type = GlobalType.from_reader(r)
o.expr = Expression.from_reader(r)
return o
class GlobalSection:
# The global section has the id 6. It decodes into a vector of globals
# that represent the globals component of a module.
#
# globalsec ::= glob*:section6(vec(global)) ⇒ glob∗
# global ::= gt:globaltype e:expr ⇒ {type gt, init e}
def __init__(self):
self.data: typing.List[Global] = []
def __repr__(self):
return f'global_section({self.data})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = GlobalSection()
n = leb128.u.decode_reader(r)[0]
o.data = [Global.from_reader(r) for _ in range(n)]
return o
class Export:
# The exports component of a module defines a set of exports that become accessible to the host environment once
# the module has been instantiated.
#
# export ::= {name name, desc exportdesc}
# exportdesc ::= func funcidx | table tableidx | mem memidx | global globalidx
#
# Each export is labeled by a unique name. Exportable definitions are functions, tables, memories, and globals,
# which are referenced through a respective descriptor.
def __init__(self):
self.name: str = ''
self.type: int = 0x00
self.desc: typing.Union[FunctionIndex, TableIndex, MemoryIndex, GlobalIndex] = 0x00
def __repr__(self):
return f'export({self.name}, {self.desc})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = Export()
o.name = bytearray(r.read(leb128.u.decode_reader(r)[0])).decode()
o.type = ord(r.read(1))
o.desc = {
convention.extern_function: FunctionIndex.from_reader,
convention.extern_table: TableIndex.from_reader,
convention.extern_memory: MemoryIndex.from_reader,
convention.extern_global: GlobalIndex.from_reader,
}[o.type](r)
return o
class ExportSection:
# The export section has the id 7. It decodes into a vector of exports
# that represent the exports component of a module.
#
# exportsec ::= ex∗:section7(vec(export)) ⇒ ex∗
# export :: =nm:name d:exportdesc ⇒ {name nm, desc d}
# exportdesc ::= 0x00 x:funcidx ⇒ func x
# | 0x01 x:tableidx ⇒ table x
# | 0x02 x:memidx ⇒ mem x
# | 0x03 x:globalidx⇒global x
def __init__(self):
self.data: typing.List[Export] = []
def __repr__(self):
return f'export_section({self.data})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = ExportSection()
n = leb128.u.decode_reader(r)[0]
o.data = [Export.from_reader(r) for _ in range(n)]
return o
class StartFunction:
# The start component of a module declares the function index of a start function that is automatically invoked
# when the module is instantiated, after tables and memories have been initialized.
#
# start ::= {func funcidx}
def __init__(self):
self.function_idx: FunctionIndex = FunctionIndex()
def __repr__(self):
return f'start_function({self.function_idx})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = StartFunction()
o.function_idx = FunctionIndex.from_reader(r)
return o
class StartSection:
# The start section has the id 8. It decodes into an optional start
# function that represents the start component of a module.
#
# startsec ::= st?:section8(start) ⇒ st?
# start ::= x:funcidx ⇒ {func x}
def __init__(self):
self.start: StartFunction = StartFunction()
def __repr__(self):
return f'start_section({self.start})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = StartSection()
o.start = StartFunction.from_reader(r)
return o
class Element:
# The initial contents of a table is uninitialized. The elem component of a module defines a vector of element
# segments that initialize a subrange of a table, at a given offset, from a static vector of elements.
#
# elem ::= {table tableidx, offset expr, init vec(funcidx)}
#
# The offset is given by a constant expression.
def __init__(self):
self.table_index: TableIndex = 0x00
self.offset: Expression = Expression()
self.init: typing.List[FunctionIndex] = []
def __repr__(self):
return f'element({self.table_index}, {self.offset}, {self.init})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = Element()
o.table_index = TableIndex.from_reader(r)
o.offset = Expression.from_reader(r)
n = leb128.u.decode_reader(r)[0]
o.init = [FunctionIndex.from_reader(r) for _ in range(n)]
return o
class ElementSection:
# The element section has the id 9. It decodes into a vector of element
# segments that represent the elem component of a module.
#
# elemsec ::= seg∗:section9(vec(elem)) ⇒ seg
# elem ::= x:tableidx e:expr y∗:vec(funcidx) ⇒ {table x, offset e, init y∗}
def __init__(self):
self.data: typing.List[Element] = []
def __repr__(self):
return f'element_section({self.data})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = ElementSection()
n = leb128.u.decode_reader(r)[0]
o.data = [Element.from_reader(r) for _ in range(n)]
return o
class Locals:
# The locals declare a vector of mutable local variables and their types. These variables are referenced through
# local indices in the function’s body. The index of the first local is the smallest index not referencing a
# parameter.
#
# locals ::= n:u32 t:valtype ⇒ tn
def __init__(self):
self.n: int = 0x00
self.type: ValueType = ValueType()
def __repr__(self):
return f'locals({self.n}, {self.type})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = Locals()
o.n = leb128.u.decode_reader(r)[0]
if o.n > 0x10000000:
raise Exception('pywasm: too many locals')
o.type = ValueType.from_reader(r)
return o
class Func:
def __init__(self):
self.local_list: typing.List[Locals] = []
self.expr: Expression = Expression()
def __repr__(self):
return f'func({self.local_list}, {self.expr})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = Func()
n = leb128.u.decode_reader(r)[0]
o.local_list = [Locals.from_reader(r) for i in range(n)]
o.expr = Expression.from_reader(r)
return o
class Code:
# The encoding of each code entry consists of
# - the u32 size of the function code in bytes
# - the actual function code, which in turn consists of
# - the declaration of locals
# - the function body as an expression.
#
# Local declarations are compressed into a vector whose entries consist of
# - a u32 count
# - a value type.
#
# code ::= size:u32 code:func ⇒ code(ifsize=||func||)
# func ::= (t∗)∗:vec(locals) e:expr ⇒ concat((t∗)∗), e∗(if|concat((t∗)∗)|<232)
# locals ::= n:u32 t:valtype ⇒ tn
def __init__(self):
self.size: int = 0x00
self.func: Func = Func()
def __repr__(self):
return f'code({self.size}, {self.func})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = Code()
o.size = leb128.u.decode_reader(r)[0]
r = io.BytesIO(r.read(o.size))
o.func = Func.from_reader(r)
return o
class CodeSection:
# The code section has the id 10. It decodes into a vector of code
# entries that are pairs of value type vectors and expressions. They
# represent the locals and body field of the functions in the funcs
# component of a module. The type fields of the respective functions are
# encoded separately in the function section.
def __init__(self):
self.data: typing.List[Code] = []
def __repr__(self):
return f'code_section({self.data})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = CodeSection()
n = leb128.u.decode_reader(r)[0]
o.data = [Code.from_reader(r) for _ in range(n)]
return o
class Data:
# The initial contents of a memory are zero-valued bytes. The data component of a module defines a vector of data
# segments that initialize a range of memory, at a given offset, with a static vector of bytes.
#
# data::={data memidx,offset expr,init vec(byte)}
#
# The offset is given by a constant expression.
def __init__(self):
self.memory_index: MemoryIndex = MemoryIndex()
self.offset: Expression = Expression()
self.init: bytearray = bytearray()
def __repr__(self):
return f'data({self.memory_index}, {self.offset}, {self.init})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = Data()
o.memory_index = MemoryIndex.from_reader(r)
o.offset = Expression.from_reader(r)
n = leb128.u.decode_reader(r)[0]
o.init = bytearray(r.read(n))
if len(o.init) != n:
raise Exception('pywasm: unexpected end of section or function')
return o
class DataSection:
# The data section has the id 11. It decodes into a vector of data
# segments that represent the data component of a module.
#
# datasec ::= seg∗:section11(vec(data)) ⇒ seg
# data ::= x:memidx e:expr b∗:vec(byte) ⇒ {data x,offset e,init b∗}
def __init__(self):
self.data: typing.List[Data] = []
def __repr__(self):
return f'data_section({self.data})'
@classmethod
def from_reader(cls, r: typing.BinaryIO):
o = DataSection()
n = leb128.u.decode_reader(r)[0]
o.data = [Data.from_reader(r) for _ in range(n)]
return o
class Function:
# The funcs component of a module defines a vector of functions with the following structure:
#
# func ::= {type typeidx, locals vec(valtype), body expr}
#
# The type of a function declares its signature by reference to a type defined in the module. The parameters of the
# function are referenced through 0-based local indices in the function’s body; they are mutable.
#
# The locals declare a vector of mutable local variables and their types. These variables are referenced through
# local indices in the function’s body. The index of the first local is the smallest index not referencing a
# parameter.
#
# The body is an instruction sequence that upon termination must produce a stack matching the function type’s
# result type.
#