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admin/node_modules/@parcel/watcher/src/wasm/WasmBackend.cc

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+#include <sys/stat.h>
+#include "WasmBackend.hh"
+
+#define CONVERT_TIME(ts) ((uint64_t)ts.tv_sec * 1000000000 + ts.tv_nsec)
+
+void WasmBackend::start() {
+  notifyStarted();
+}
+
+void WasmBackend::subscribe(WatcherRef watcher) {
+  // Build a full directory tree recursively, and watch each directory.
+  std::shared_ptr<DirTree> tree = getTree(watcher);
+
+  for (auto it = tree->entries.begin(); it != tree->entries.end(); it++) {
+    if (it->second.isDir) {
+      watchDir(watcher, it->second.path, tree);
+    }
+  }
+}
+
+void WasmBackend::watchDir(WatcherRef watcher, std::string path, std::shared_ptr<DirTree> tree) {
+  int wd = wasm_backend_add_watch(path.c_str(), (void *)this);
+  std::shared_ptr<WasmSubscription> sub = std::make_shared<WasmSubscription>();
+  sub->tree = tree;
+  sub->path = path;
+  sub->watcher = watcher;
+  mSubscriptions.emplace(wd, sub);
+}
+
+extern "C" void wasm_backend_event_handler(void *backend, int wd, int type, char *filename) {
+  WasmBackend *b = (WasmBackend *)(backend);
+  b->handleEvent(wd, type, filename);
+}
+
+void WasmBackend::handleEvent(int wd, int type, char *filename) {
+  // Find the subscriptions for this watch descriptor
+  auto range = mSubscriptions.equal_range(wd);
+  std::unordered_set<std::shared_ptr<WasmSubscription>> set;
+  for (auto it = range.first; it != range.second; it++) {
+    set.insert(it->second);
+  }
+
+  for (auto it = set.begin(); it != set.end(); it++) {
+    if (handleSubscription(type, filename, *it)) {
+      (*it)->watcher->notify();
+    }
+  }
+}
+
+bool WasmBackend::handleSubscription(int type, char *filename, std::shared_ptr<WasmSubscription> sub) {
+  // Build full path and check if its in our ignore list.
+  WatcherRef watcher = sub->watcher;
+  std::string path = std::string(sub->path);
+
+  if (filename[0] != '\0') {
+    path += "/" + std::string(filename);
+  }
+
+  if (watcher->isIgnored(path)) {
+    return false;
+  }
+
+  if (type == 1) {
+    struct stat st;
+    stat(path.c_str(), &st);
+    sub->tree->update(path, CONVERT_TIME(st.st_mtim));
+    watcher->mEvents.update(path);
+  } else if (type == 2) {
+    // Determine if this is a create or delete depending on if the file exists or not.
+    struct stat st;
+    if (lstat(path.c_str(), &st)) {
+      // If the entry being deleted/moved is a directory, remove it from the list of subscriptions
+      DirEntry *entry = sub->tree->find(path);
+      if (!entry) {
+        return false;
+      }
+
+      if (entry->isDir) {
+        std::string pathStart = path + DIR_SEP;
+        for (auto it = mSubscriptions.begin(); it != mSubscriptions.end();) {
+          if (it->second->path == path || it->second->path.rfind(pathStart, 0) == 0) {
+            wasm_backend_remove_watch(it->first);
+            it = mSubscriptions.erase(it);
+          } else {
+            ++it;
+          }
+        }
+
+        // Remove all sub-entries
+        for (auto it = sub->tree->entries.begin(); it != sub->tree->entries.end();) {
+          if (it->first.rfind(pathStart, 0) == 0) {
+            watcher->mEvents.remove(it->first);
+            it = sub->tree->entries.erase(it);
+          } else {
+            it++;
+          }
+        }
+      }
+
+      watcher->mEvents.remove(path);
+      sub->tree->remove(path);
+    } else if (sub->tree->find(path)) {
+      sub->tree->update(path, CONVERT_TIME(st.st_mtim));
+      watcher->mEvents.update(path);
+    } else {
+      watcher->mEvents.create(path);
+
+      // If this is a create, check if it's a directory and start watching if it is.
+      DirEntry *entry = sub->tree->add(path, CONVERT_TIME(st.st_mtim), S_ISDIR(st.st_mode));
+      if (entry->isDir) {
+        watchDir(watcher, path, sub->tree);
+      }
+    }
+  }
+
+  return true;
+}
+
+void WasmBackend::unsubscribe(WatcherRef watcher) {
+  // Find any subscriptions pointing to this watcher, and remove them.
+  for (auto it = mSubscriptions.begin(); it != mSubscriptions.end();) {
+    if (it->second->watcher.get() == watcher.get()) {
+      if (mSubscriptions.count(it->first) == 1) {
+        wasm_backend_remove_watch(it->first);
+      }
+
+      it = mSubscriptions.erase(it);
+    } else {
+      it++;
+    }
+  }
+}