spike: validate WASM phase 0

spikes/wasm-phase0/wasm_inspect.py

@@ -0,0 +1,95 @@
+#!/usr/bin/env python3
+"""Phase 0 helper: dump a wasm module's imports, exports, and dylink.0
+custom section (memory/table size requirements). Doubles as the reference
+for the loader's dylink.0 parsing (§6 step 4)."""
+import sys, struct
+
+def uleb(buf, pos):
+    result = 0
+    shift = 0
+    while True:
+        b = buf[pos]
+        pos += 1
+        result |= (b & 0x7f) << shift
+        if not (b & 0x80):
+            return result, pos
+        shift += 7
+
+def name(buf, pos):
+    n, pos = uleb(buf, pos)
+    return buf[pos:pos+n].decode("utf-8", "replace"), pos + n
+
+def limits(buf, pos):
+    flags = buf[pos]; pos += 1
+    mn, pos = uleb(buf, pos)
+    mx = None
+    if flags & 1:
+        mx, pos = uleb(buf, pos)
+    return (mn, mx), pos
+
+KIND = {0: "func", 1: "table", 2: "memory", 3: "global"}
+VALTYPE = {0x7f: "i32", 0x7e: "i64", 0x7d: "f32", 0x7c: "f64", 0x70: "funcref", 0x6f: "externref"}
+
+def main(fn):
+    buf = open(fn, "rb").read()
+    assert buf[:8] == b"\0asm\x01\0\0\0", "not a wasm module"
+    pos = 8
+    while pos < len(buf):
+        sec_id = buf[pos]; pos += 1
+        size, pos = uleb(buf, pos)
+        end = pos + size
+        if sec_id == 0:
+            sname, p = name(buf, pos)
+            if sname == "dylink.0":
+                print("== dylink.0 ==")
+                while p < end:
+                    sub = buf[p]; p += 1
+                    sublen, p = uleb(buf, p)
+                    subend = p + sublen
+                    if sub == 1:  # WASM_DYLINK_MEM_INFO
+                        memsize, p2 = uleb(buf, p)
+                        memalign, p2 = uleb(buf, p2)
+                        tabsize, p2 = uleb(buf, p2)
+                        tabalign, p2 = uleb(buf, p2)
+                        print(f"  mem_info: memsize={memsize} memalign=2^{memalign} tablesize={tabsize} tablealign=2^{tabalign}")
+                    else:
+                        print(f"  subsection type={sub} len={sublen}")
+                    p = subend
+            elif sname in ("uce.abi",):
+                print(f"== custom section {sname} ({end - p} bytes) ==")
+        elif sec_id == 2:
+            count, p = uleb(buf, pos)
+            print(f"== imports ({count}) ==")
+            for _ in range(count):
+                mod, p = name(buf, p)
+                nm, p = name(buf, p)
+                kind = buf[p]; p += 1
+                detail = ""
+                if kind == 0:
+                    _, p = uleb(buf, p)
+                elif kind == 1:
+                    et = buf[p]; p += 1
+                    lim, p = limits(buf, p)
+                    detail = f" {VALTYPE.get(et, hex(et))} {lim}"
+                elif kind == 2:
+                    lim, p = limits(buf, p)
+                    detail = f" {lim}"
+                elif kind == 3:
+                    vt = buf[p]; p += 1
+                    mut = buf[p]; p += 1
+                    detail = f" {VALTYPE.get(vt, hex(vt))}{' mut' if mut else ''}"
+                print(f"  {KIND.get(kind, kind):6} {mod}.{nm}{detail}")
+        elif sec_id == 7:
+            count, p = uleb(buf, pos)
+            print(f"== exports ({count}) ==")
+            for _ in range(count):
+                nm, p = name(buf, p)
+                kind = buf[p]; p += 1
+                _, p = uleb(buf, p)
+                print(f"  {KIND.get(kind, kind):6} {nm}")
+        pos = end
+
+if __name__ == "__main__":
+    for fn in sys.argv[1:]:
+        print(f"### {fn}")
+        main(fn)