src/hooks.cpp


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// hooks.cpp — vtable hook installation and teardown bookkeeping.
#include "hl2h.h"

#include <mutex>
#include <vector>

namespace {

struct Installed {
  void *iface;
  void **old_vt;
};

std::mutex g_hook_mu;
std::vector<Installed> g_installed;

} // namespace

bool hooks_install_vtable(void *iface, size_t slots, const VtablePatch *patches,
                          int count) {
  if (!iface || !patches || count <= 0)
    return false;
  void **old = *(void ***)iface;
  if (!old)
    return false;
  for (int i = 0; i < count; i++) {
    if (patches[i].slot < 0 || (size_t)patches[i].slot >= slots) {
      logf("hooks: slot %d out of range (table has %u)", patches[i].slot,
           (unsigned)slots);
      return false;
    }
  }

  void **clone = vtable_clone(iface, slots);
  if (!clone)
    return false;
  for (int i = 0; i < count; i++) {
    if (patches[i].original)
      *patches[i].original = old[patches[i].slot];
    clone[patches[i].slot] = patches[i].replacement;
  }

  std::lock_guard<std::mutex> lock(g_hook_mu);
  *(void ***)iface = clone;
  g_installed.push_back({iface, old});
  return true;
}

void hooks_restore_all() {
  std::lock_guard<std::mutex> lock(g_hook_mu);
  for (auto it = g_installed.rbegin(); it != g_installed.rend(); ++it)
    *(void ***)it->iface = it->old_vt;
  g_installed.clear();
}

int hooks_installed_count() {
  std::lock_guard<std::mutex> lock(g_hook_mu);
  return (int)g_installed.size();
}