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vatrog-vm-introspection-engine/src/handlers/semsig_stub.c
T
lirent 1b06206043 Add operand-normalized semantic code signatures
New semsig_hash(mem_view_t) primitive (include/semsig.h): a position-,
register-, immediate- and instruction-order-invariant function fingerprint.
It folds per-instruction operand-canonical tokens, splitting the body into
basic blocks via cfg_blocks and using a within-block order-insensitive
sort-then-fold (between-block order preserved), so it survives compiler
register reallocation and instruction scheduling that the byte-mask
func_hash/sig_generate cannot. Distinct hash domain from func_hash.

The operand decode is delegated to an OPTIONAL external disassembler behind
a private adapter seam (src/handlers/semsig_backend.h); semsig.c stays
backend-neutral and includes no backend header. VMIE_DISASM={OFF|zydis|
capstone} gates the build: OFF (default) compiles only semsig_stub.c and
keeps the zero-dependency build (VMIE_HAVE_DISASM=0, packages unchanged).
The backend is brought from VMIE_DISASM_SRC or find_package - never
vendored. Adds the vmie_win32_func_semsig wrapper.

The CI deb job builds with the Zydis backend (libzydis-dev); the runtime
package dependency on libzydis is derived automatically by dpkg-shlibdeps.
2026-06-28 21:51:47 +03:00

27 lines
1.0 KiB
C

/* semsig_stub.c - the OFF (no-backend) path of the semantic-signature feature.
*
* Built into the library ONLY when VMIE_DISASM=OFF (the default). It provides
* the full public generic surface so the ABI is stable - linking never fails
* for a missing symbol - while the feature is not present:
* semsig_hash -> 0 (the same "no hash" sentinel as func_hash)
* semsig_backend_name -> "none"
* Callers tell "feature off" from "empty/undecodable function" via the compile-
* time macro VMIE_HAVE_DISASM (0 here), NOT via the runtime 0.
*
* In the OFF build semsig.c is NOT compiled (it calls the backend decode, which
* does not exist without a backend); this stub is the whole generic symbol. See
* CMakeLists.txt for the source-selection logic.
*/
#include <stdint.h>
#include "semsig.h"
uint64_t semsig_hash(mem_view_t fn) __attribute__((cold));
uint64_t semsig_hash(mem_view_t fn) {
(void)fn;
return 0; /* feature not built: same sentinel as func_hash */
}
const char* semsig_backend_name(void) {
return "none";
}