wasmgdb

gdb for WebAssembly

Install

cargo install wasmgdb

Usage

Use wasm-edit to transform your module and, once WebAssembly traps, collect the WebAssembly memory and analyze the coredump.

Analyze a coredump

wasmgdb <coredump> <source.wasm>

Commands

bt

Display the stack trace.

f <#>

Selects a stack frame and display informations.

p <expr>

Inspect the content of a variable. Requires to select the frame with f first.

p *<expr>

Inspect the content of a variable after dereferencing it. Requires to select the frame with f first.

p/s <expr>

Print the variable as string. Requires to select the frame with f first.

p (<type>) <expr>

Print the content of as .

x/<number> <hex-addr>

Examine the memory address at with length.

x/<number>s <hex-addr>

Examine the memory address at and prints as string of length.

find <expr>

Find the as bytes in memory.

Usage: find <start-addr>, <end-addr>, <expr> find <expr>

info types

List all defined types.

info locals

List local values (includes Wasm func arguments).

info symbol <funcidx>

Get informations about the function at the given index.

info imports

List WebAssembly module's imported functions from the host.

Expr

• Member access: <object>-><member>
• Cast: (<type>) <hex-addr>
• String: "<string>"