1/* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#ifndef __TRACE_DEV_INC 18#define __TRACE_DEV_INC 19 20#define LOG_TAG "cutils-trace" 21 22#include <errno.h> 23#include <fcntl.h> 24#include <limits.h> 25#include <pthread.h> 26#include <stdatomic.h> 27#include <stdbool.h> 28#include <stdlib.h> 29#include <string.h> 30#include <sys/types.h> 31 32#include <cutils/compiler.h> 33#include <cutils/properties.h> 34#include <cutils/trace.h> 35#include <log/log.h> 36#include <log/log_properties.h> 37 38/** 39 * Maximum size of a message that can be logged to the trace buffer. 40 * Note this message includes a tag, the pid, and the string given as the name. 41 * Names should be kept short to get the most use of the trace buffer. 42 */ 43#define ATRACE_MESSAGE_LENGTH 1024 44 45atomic_bool atrace_is_ready = ATOMIC_VAR_INIT(false); 46int atrace_marker_fd = -1; 47uint64_t atrace_enabled_tags = ATRACE_TAG_NOT_READY; 48static bool atrace_is_debuggable = false; 49static atomic_bool atrace_is_enabled = ATOMIC_VAR_INIT(true); 50static pthread_mutex_t atrace_tags_mutex = PTHREAD_MUTEX_INITIALIZER; 51 52// Set whether this process is debuggable, which determines whether 53// application-level tracing is allowed when the ro.debuggable system property 54// is not set to '1'. 55void atrace_set_debuggable(bool debuggable) 56{ 57 atrace_is_debuggable = debuggable; 58 atrace_update_tags(); 59} 60 61// Check whether the given command line matches one of the comma-separated 62// values listed in the app_cmdlines property. 63static bool atrace_is_cmdline_match(const char* cmdline) 64{ 65 int count = property_get_int32("debug.atrace.app_number", 0); 66 67 char buf[PROPERTY_KEY_MAX]; 68 char value[PROPERTY_VALUE_MAX]; 69 70 for (int i = 0; i < count; i++) { 71 snprintf(buf, sizeof(buf), "debug.atrace.app_%d", i); 72 property_get(buf, value, ""); 73 if (strcmp(value, "*") == 0 || strcmp(value, cmdline) == 0) { 74 return true; 75 } 76 } 77 78 return false; 79} 80 81// Determine whether application-level tracing is enabled for this process. 82static bool atrace_is_app_tracing_enabled() 83{ 84 bool sys_debuggable = __android_log_is_debuggable(); 85 bool result = false; 86 87 if (sys_debuggable || atrace_is_debuggable) { 88 // Check whether tracing is enabled for this process. 89 FILE * file = fopen("/proc/self/cmdline", "re"); 90 if (file) { 91 char cmdline[4096]; 92 if (fgets(cmdline, sizeof(cmdline), file)) { 93 result = atrace_is_cmdline_match(cmdline); 94 } else { 95 ALOGE("Error reading cmdline: %s (%d)", strerror(errno), errno); 96 } 97 fclose(file); 98 } else { 99 ALOGE("Error opening /proc/self/cmdline: %s (%d)", strerror(errno), 100 errno); 101 } 102 } 103 104 return result; 105} 106 107// Read the sysprop and return the value tags should be set to 108static uint64_t atrace_get_property() 109{ 110 char value[PROPERTY_VALUE_MAX]; 111 char *endptr; 112 uint64_t tags; 113 114 property_get("debug.atrace.tags.enableflags", value, "0"); 115 errno = 0; 116 tags = strtoull(value, &endptr, 0); 117 if (value[0] == '\0' || *endptr != '\0') { 118 ALOGE("Error parsing trace property: Not a number: %s", value); 119 return 0; 120 } else if (errno == ERANGE || tags == ULLONG_MAX) { 121 ALOGE("Error parsing trace property: Number too large: %s", value); 122 return 0; 123 } 124 125 // Only set the "app" tag if this process was selected for app-level debug 126 // tracing. 127 if (atrace_is_app_tracing_enabled()) { 128 tags |= ATRACE_TAG_APP; 129 } else { 130 tags &= ~ATRACE_TAG_APP; 131 } 132 133 return (tags | ATRACE_TAG_ALWAYS) & ATRACE_TAG_VALID_MASK; 134} 135 136// Update tags if tracing is ready. Useful as a sysprop change callback. 137void atrace_update_tags() 138{ 139 uint64_t tags; 140 if (CC_UNLIKELY(atomic_load_explicit(&atrace_is_ready, memory_order_acquire))) { 141 if (atomic_load_explicit(&atrace_is_enabled, memory_order_acquire)) { 142 tags = atrace_get_property(); 143 pthread_mutex_lock(&atrace_tags_mutex); 144 atrace_enabled_tags = tags; 145 pthread_mutex_unlock(&atrace_tags_mutex); 146 } else { 147 // Tracing is disabled for this process, so we simply don't 148 // initialize the tags. 149 pthread_mutex_lock(&atrace_tags_mutex); 150 atrace_enabled_tags = ATRACE_TAG_NOT_READY; 151 pthread_mutex_unlock(&atrace_tags_mutex); 152 } 153 } 154} 155 156#define WRITE_MSG(format_begin, format_end, name, value) { \ 157 char buf[ATRACE_MESSAGE_LENGTH]; \ 158 int pid = getpid(); \ 159 int len = snprintf(buf, sizeof(buf), format_begin "%s" format_end, pid, \ 160 name, value); \ 161 if (len >= (int) sizeof(buf)) { \ 162 /* Given the sizeof(buf), and all of the current format buffers, \ 163 * it is impossible for name_len to be < 0 if len >= sizeof(buf). */ \ 164 int name_len = strlen(name) - (len - sizeof(buf)) - 1; \ 165 /* Truncate the name to make the message fit. */ \ 166 ALOGW("Truncated name in %s: %s\n", __FUNCTION__, name); \ 167 len = snprintf(buf, sizeof(buf), format_begin "%.*s" format_end, pid, \ 168 name_len, name, value); \ 169 } \ 170 write(atrace_marker_fd, buf, len); \ 171} 172 173#endif // __TRACE_DEV_INC 174