wasmdump

Japanese

wasmdump is a small WebAssembly binary dumper written in C. It reads a .wasm file and prints its module header, sections, imports, exports, type information, code bodies, locals, and decoded instructions in a human-readable text format.

Build

cc -std=c99 -Wall -Wextra -O2 -o wasmdump wasmdump.c

Usage

./wasmdump file.wasm

Example output:

wasm: version=1 size=...
section[1] type offset=0x000a size=...
  count: ...
section[7] export offset=0x.... size=...
  export[0]: "..." func=...
section[10] code offset=0x.... size=...
  code[0]: size=...
    locals groups: ...
    0010  local.get        0
    0012  i32.const        1
    0014  i32.add
    0015  end

Supported Output

The dumper recognizes standard WebAssembly sections such as:

• custom
• type
• import
• function
• table
• memory
• global
• export
• start
• element
• code
• data
• data_count

It also decodes many common instructions, including control flow, calls, locals/globals, memory loads and stores, constants, comparisons, and basic i32 arithmetic and bit operations.

Notes

This is a compact inspection tool, not a full WebAssembly validator or disassembler. Unknown sections and instructions are still reported, but not all WebAssembly proposals or extended opcode spaces are decoded in detail.