1 files changed, 242 insertions, 0 deletions
diff --git a/libcutils/trace-dev.c b/libcutils/trace-dev.c
new file mode 100644
index 0000000..a06987e
--- /dev/null
+++ b/libcutils/trace-dev.c
@@ -0,0 +1,242 @@
+/*
+ * Copyright (C) 2012 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 <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <pthread.h>
+#include <stdatomic.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <cutils/compiler.h>
+#include <cutils/properties.h>
+#include <cutils/trace.h>
+
+#define LOG_TAG "cutils-trace"
+#include <log/log.h>
+
+/**
+ * Maximum size of a message that can be logged to the trace buffer.
+ * Note this message includes a tag, the pid, and the string given as the name.
+ * Names should be kept short to get the most use of the trace buffer.
+ */
+#define ATRACE_MESSAGE_LENGTH 1024
+
+atomic_bool             atrace_is_ready      = ATOMIC_VAR_INIT(false);
+int                     atrace_marker_fd     = -1;
+uint64_t                atrace_enabled_tags  = ATRACE_TAG_NOT_READY;
+static bool             atrace_is_debuggable = false;
+static atomic_bool      atrace_is_enabled    = ATOMIC_VAR_INIT(true);
+static pthread_once_t   atrace_once_control  = PTHREAD_ONCE_INIT;
+static pthread_mutex_t  atrace_tags_mutex    = PTHREAD_MUTEX_INITIALIZER;
+
+// Set whether this process is debuggable, which determines whether
+// application-level tracing is allowed when the ro.debuggable system property
+// is not set to '1'.
+void atrace_set_debuggable(bool debuggable)
+{
+    atrace_is_debuggable = debuggable;
+    atrace_update_tags();
+}
+
+// Set whether tracing is enabled in this process.  This is used to prevent
+// the Zygote process from tracing.
+void atrace_set_tracing_enabled(bool enabled)
+{
+    atomic_store_explicit(&atrace_is_enabled, enabled, memory_order_release);
+    atrace_update_tags();
+}
+
+// Check whether the given command line matches one of the comma-separated
+// values listed in the app_cmdlines property.
+static bool atrace_is_cmdline_match(const char* cmdline)
+{
+    char value[PROPERTY_VALUE_MAX];
+    char* start = value;
+
+    property_get("debug.atrace.app_cmdlines", value, "");
+
+    while (start != NULL) {
+        char* end = strchr(start, ',');
+
+        if (end != NULL) {
+            *end = '\0';
+            end++;
+        }
+
+        if (strcmp(cmdline, start) == 0) {
+            return true;
+        }
+
+        start = end;
+    }
+
+    return false;
+}
+
+// Determine whether application-level tracing is enabled for this process.
+static bool atrace_is_app_tracing_enabled()
+{
+    bool sys_debuggable = false;
+    char value[PROPERTY_VALUE_MAX];
+    bool result = false;
+
+    // Check whether the system is debuggable.
+    property_get("ro.debuggable", value, "0");
+    if (value[0] == '1') {
+        sys_debuggable = true;
+    }
+
+    if (sys_debuggable || atrace_is_debuggable) {
+        // Check whether tracing is enabled for this process.
+        FILE * file = fopen("/proc/self/cmdline", "r");
+        if (file) {
+            char cmdline[4096];
+            if (fgets(cmdline, sizeof(cmdline), file)) {
+                result = atrace_is_cmdline_match(cmdline);
+            } else {
+                ALOGE("Error reading cmdline: %s (%d)", strerror(errno), errno);
+            }
+            fclose(file);
+        } else {
+            ALOGE("Error opening /proc/self/cmdline: %s (%d)", strerror(errno),
+                    errno);
+        }
+    }
+
+    return result;
+}
+
+// Read the sysprop and return the value tags should be set to
+static uint64_t atrace_get_property()
+{
+    char value[PROPERTY_VALUE_MAX];
+    char *endptr;
+    uint64_t tags;
+
+    property_get("debug.atrace.tags.enableflags", value, "0");
+    errno = 0;
+    tags = strtoull(value, &endptr, 0);
+    if (value[0] == '\0' || *endptr != '\0') {
+        ALOGE("Error parsing trace property: Not a number: %s", value);
+        return 0;
+    } else if (errno == ERANGE || tags == ULLONG_MAX) {
+        ALOGE("Error parsing trace property: Number too large: %s", value);
+        return 0;
+    }
+
+    // Only set the "app" tag if this process was selected for app-level debug
+    // tracing.
+    if (atrace_is_app_tracing_enabled()) {
+        tags |= ATRACE_TAG_APP;
+    } else {
+        tags &= ~ATRACE_TAG_APP;
+    }
+
+    return (tags | ATRACE_TAG_ALWAYS) & ATRACE_TAG_VALID_MASK;
+}
+
+// Update tags if tracing is ready. Useful as a sysprop change callback.
+void atrace_update_tags()
+{
+    uint64_t tags;
+    if (CC_UNLIKELY(atomic_load_explicit(&atrace_is_ready, memory_order_acquire))) {
+        if (atomic_load_explicit(&atrace_is_enabled, memory_order_acquire)) {
+            tags = atrace_get_property();
+            pthread_mutex_lock(&atrace_tags_mutex);
+            atrace_enabled_tags = tags;
+            pthread_mutex_unlock(&atrace_tags_mutex);
+        } else {
+            // Tracing is disabled for this process, so we simply don't
+            // initialize the tags.
+            pthread_mutex_lock(&atrace_tags_mutex);
+            atrace_enabled_tags = ATRACE_TAG_NOT_READY;
+            pthread_mutex_unlock(&atrace_tags_mutex);
+        }
+    }
+}
+
+static void atrace_init_once()
+{
+    atrace_marker_fd = open("/sys/kernel/debug/tracing/trace_marker", O_WRONLY);
+    if (atrace_marker_fd == -1) {
+        ALOGE("Error opening trace file: %s (%d)", strerror(errno), errno);
+        atrace_enabled_tags = 0;
+        goto done;
+    }
+
+    atrace_enabled_tags = atrace_get_property();
+
+done:
+    atomic_store_explicit(&atrace_is_ready, true, memory_order_release);
+}
+
+void atrace_setup()
+{
+    pthread_once(&atrace_once_control, atrace_init_once);
+}
+
+void atrace_begin_body(const char* name)
+{
+    char buf[ATRACE_MESSAGE_LENGTH];
+    size_t len;
+
+    len = snprintf(buf, ATRACE_MESSAGE_LENGTH, "B|%d|%s", getpid(), name);
+    write(atrace_marker_fd, buf, len);
+}
+
+
+void atrace_async_begin_body(const char* name, int32_t cookie)
+{
+    char buf[ATRACE_MESSAGE_LENGTH];
+    size_t len;
+
+    len = snprintf(buf, ATRACE_MESSAGE_LENGTH, "S|%d|%s|%" PRId32,
+            getpid(), name, cookie);
+    write(atrace_marker_fd, buf, len);
+}
+
+void atrace_async_end_body(const char* name, int32_t cookie)
+{
+    char buf[ATRACE_MESSAGE_LENGTH];
+    size_t len;
+
+    len = snprintf(buf, ATRACE_MESSAGE_LENGTH, "F|%d|%s|%" PRId32,
+            getpid(), name, cookie);
+    write(atrace_marker_fd, buf, len);
+}
+
+void atrace_int_body(const char* name, int32_t value)
+{
+    char buf[ATRACE_MESSAGE_LENGTH];
+    size_t len;
+
+    len = snprintf(buf, ATRACE_MESSAGE_LENGTH, "C|%d|%s|%" PRId32,
+            getpid(), name, value);
+    write(atrace_marker_fd, buf, len);
+}
+
+void atrace_int64_body(const char* name, int64_t value)
+{
+    char buf[ATRACE_MESSAGE_LENGTH];
+    size_t len;
+
+    len = snprintf(buf, ATRACE_MESSAGE_LENGTH, "C|%d|%s|%" PRId64,
+            getpid(), name, value);
+    write(atrace_marker_fd, buf, len);
+}