Struct wasmtime::FrameInfo

pub struct FrameInfo { /* private fields */ }

Description of a frame in a backtrace for a Trap.

Whenever a WebAssembly trap occurs an instance of Trap is created. Each Trap has a backtrace of the WebAssembly frames that led to the trap, and each frame is described by this structure.

Implementations

impl FrameInfo

pub fn func_index(&self) -> u32

Returns the WebAssembly function index for this frame.

This function index is the index in the function index space of the WebAssembly module that this frame comes from.

pub fn module_name(&self) -> Option<&str>

Returns the identifer of the module that this frame is for.

Module identifiers are present in the name section of a WebAssembly binary, but this may not return the exact item in the name section. Module names can be overwritten at construction time or perhaps inferred from file names. The primary purpose of this function is to assist in debugging and therefore may be tweaked over time.

This function returns None when no name can be found or inferred.

pub fn func_name(&self) -> Option<&str>

Returns a descriptive name of the function for this frame, if one is available.

The name of this function may come from the name section of the WebAssembly binary, or wasmtime may try to infer a better name for it if not available, for example the name of the export if it’s exported.

This return value is primarily used for debugging and human-readable purposes for things like traps. Note that the exact return value may be tweaked over time here and isn’t guaranteed to be something in particular about a wasm module due to its primary purpose of assisting in debugging.

This function returns None when no name could be inferred.

pub fn module_offset(&self) -> Option<usize>

Returns the offset within the original wasm module this frame’s program counter was at.

The offset here is the offset from the beginning of the original wasm module to the instruction that this frame points to.

Note that None may be returned if the original module was not compiled with mapping information to yield this information. This is controlled by the Config::generate_address_map configuration option.

pub fn func_offset(&self) -> Option<usize>

Returns the offset from the original wasm module’s function to this frame’s program counter.

The offset here is the offset from the beginning of the defining function of this frame (within the wasm module) to the instruction this frame points to.

Note that None may be returned if the original module was not compiled with mapping information to yield this information. This is controlled by the Config::generate_address_map configuration option.

pub fn symbols(&self) -> &[FrameSymbol]

Returns the debug symbols found, if any, for this function frame.

When a wasm program is compiled with DWARF debug information then this function may be populated to return symbols which contain extra debug information about a frame including the filename and line number. If no debug information was found or if it was malformed then this will return an empty array.

Trait Implementations

impl Debug for FrameInfo

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.