/* * Copyright (C) 2017 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. */ #ifndef __TRACE_DEV_INC #define __TRACE_DEV_INC #define LOG_TAG "cutils-trace" #include #include #include #include #include #include #include #include #include #include #include #include #include #include /** * 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_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(); } // 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) { int count = property_get_int32("debug.atrace.app_number", 0); char buf[PROPERTY_KEY_MAX]; char value[PROPERTY_VALUE_MAX]; for (int i = 0; i < count; i++) { snprintf(buf, sizeof(buf), "debug.atrace.app_%d", i); property_get(buf, value, ""); if (strcmp(value, "*") == 0 || strcmp(value, cmdline) == 0) { return true; } } return false; } // Determine whether application-level tracing is enabled for this process. static bool atrace_is_app_tracing_enabled() { bool sys_debuggable = __android_log_is_debuggable(); bool result = false; if (sys_debuggable || atrace_is_debuggable) { // Check whether tracing is enabled for this process. FILE * file = fopen("/proc/self/cmdline", "re"); 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); } } } #define WRITE_MSG(format_begin, format_end, name, value) { \ char buf[ATRACE_MESSAGE_LENGTH]; \ int pid = getpid(); \ int len = snprintf(buf, sizeof(buf), format_begin "%s" format_end, pid, \ name, value); \ if (len >= (int) sizeof(buf)) { \ /* Given the sizeof(buf), and all of the current format buffers, \ * it is impossible for name_len to be < 0 if len >= sizeof(buf). */ \ int name_len = strlen(name) - (len - sizeof(buf)) - 1; \ /* Truncate the name to make the message fit. */ \ ALOGW("Truncated name in %s: %s\n", __FUNCTION__, name); \ len = snprintf(buf, sizeof(buf), format_begin "%.*s" format_end, pid, \ name_len, name, value); \ } \ write(atrace_marker_fd, buf, len); \ } #endif // __TRACE_DEV_INC