Merge SP1A.200921.001

Change-Id: Id2ab019914bb555dadf52c46b8403c0d5fb3c20a

1 files changed, 113 insertions, 0 deletions

diff --git a/libc/system_properties/prop_trace.cpp b/libc/system_properties/prop_trace.cpp
new file mode 100644
index 000000000..ac7ff9414
--- /dev/null
+++ b/libc/system_properties/prop_trace.cpp
@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "system_properties/prop_trace.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "private/CachedProperty.h"
+#include "private/bionic_lock.h"
+#include "private/bionic_systrace.h"
+
+#include <async_safe/log.h>
+#include <cutils/trace.h>  // For ATRACE_TAG_SYSPROP.
+
+#define PROP_TRACE_MSG_LENGTH 1024
+
+static bool should_trace_prop(const char* prop_name) {
+  // Should not trace kTraceTagsProp to avoid infinite recursion.
+  // Because the following g_trace_enable_flags.Get() will get the property value
+  // of kTraceTagsProp again, which in turn invokes should_trace_prop() here.
+  if (prop_name == nullptr || !strcmp(prop_name, kTraceTagsProp)) {
+    return false;
+  }
+
+  return should_trace(ATRACE_TAG_SYSPROP);
+}
+
+static void sysprop_trace_end() {
+  int trace_marker_fd = get_trace_marker_fd();
+  if (trace_marker_fd == -1) {
+    return;
+  }
+
+  TEMP_FAILURE_RETRY(write(trace_marker_fd, "E|", 2));
+}
+
+static void get_sysprop_trace_end(const prop_info* pi, const char* prop_value,
+                                  bool read_only = false) {
+  const char* output_value;
+  char message[PROP_TRACE_MSG_LENGTH];
+
+  if (read_only) {
+    if (pi->is_long()) {
+      output_value = pi->long_value();
+    } else {
+      output_value = pi->value;
+    }
+  } else {
+    output_value = prop_value;
+  }
+
+  snprintf(message, sizeof(message), "prop_get: %s, value: %s", pi->name,
+           output_value ? output_value : "null_value");
+  output_trace(message, 'E');  // 'E' for end.
+}
+
+SyspropTrace::SyspropTrace(const char* prop_name, const char* prop_value, const prop_info* pi,
+                           PropertyAction action)
+    : prop_name_(prop_name),
+      prop_value_(prop_value),
+      prop_info_(pi),
+      prop_action_(action),
+      output_trace_(false) {
+  if (!should_trace_prop(prop_name)) {
+    return;
+  }
+
+  char message[PROP_TRACE_MSG_LENGTH];
+  if (prop_action_ == PropertyAction::kPropertyFind) {
+    snprintf(message, sizeof(message), "prop_find: %s", prop_name_);
+  } else if (prop_action_ == PropertyAction::kPropertySet) {
+    snprintf(message, sizeof(message), "prop_set: %s, value: %s", prop_name_,
+             prop_value_ ? prop_value_ : "null_value");
+  } else {
+    // For property get, the prop_value_ will be resolved then printed in the destructor.
+    snprintf(message, sizeof(message), "prop_get: %s", prop_name_);
+  }
+
+  output_trace(message, 'B');  // 'B' for begin.
+  output_trace_ = true;
+}
+
+SyspropTrace::~SyspropTrace() {
+  if (!output_trace_) {
+    return;
+  }
+  if (prop_action_ == PropertyAction::kPropertyFind ||
+      prop_action_ == PropertyAction::kPropertySet) {
+    sysprop_trace_end();
+  } else if (prop_action_ == PropertyAction::kPropertyGetReadOnly) {
+    get_sysprop_trace_end(prop_info_, prop_value_, true /* read_only */);
+  } else if (prop_action_ == PropertyAction::kPropertyGetReadWrite) {
+    get_sysprop_trace_end(prop_info_, prop_value_, false /* read_only */);
+  }
+  output_trace_ = false;
+}