libcutils: write trace event into socket in container
When Android is running in a container, ftrace trace_marker may be
disabled, e.g. Chrome OS verified mode. To enable trace, a socket is
created for everyone to send trace event.
Modify libcutils so apps using it can write trace to the socket.
To achieve this goal without touching code for normal device,
trace-container.c is created for code specific to container. Shared
code between trace-dev.c and trace-container.c is moved to local
trace-dev.h.
Note that to avoid sharing FDs across different processes, Zygote closes
FD and reopen it to /dev/null if it is a socket. Therefore, we need to
manually close FD and reopen it again after forking. This is done in
the atrace_set_tracing_enabled as Zygote also use it to clear flags
during forking.
Related change:
- http://crrev.com/2400163003 (Chromium)
- http://ag/2028075 (Android system/core)
- http://ag/1738271 (Android device/google/cheets2)
Bug: 29776474, 62410809
Test: run chrome://tracing and see data from the host side.
Change-Id: I3fe969e284b972c28e4f32f23cd948aaea61a043
diff --git a/libcutils/trace-dev.c b/libcutils/trace-dev.c
index d45e5a9..4468e83 100644
--- a/libcutils/trace-dev.c
+++ b/libcutils/trace-dev.c
@@ -14,47 +14,9 @@
* limitations under the License.
*/
-#define LOG_TAG "cutils-trace"
+#include "trace-dev.inc"
-#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>
-#include <log/log.h>
-#include <log/log_properties.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();
-}
+static pthread_once_t atrace_once_control = PTHREAD_ONCE_INIT;
// Set whether tracing is enabled in this process. This is used to prevent
// the Zygote process from tracing.
@@ -64,101 +26,6 @@
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, 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);
- }
- }
-}
-
static void atrace_init_once()
{
atrace_marker_fd = open("/sys/kernel/debug/tracing/trace_marker", O_WRONLY | O_CLOEXEC);
@@ -181,54 +48,30 @@
void atrace_begin_body(const char* name)
{
- char buf[ATRACE_MESSAGE_LENGTH];
-
- int len = snprintf(buf, sizeof(buf), "B|%d|%s", getpid(), name);
- if (len >= (int) sizeof(buf)) {
- ALOGW("Truncated name in %s: %s\n", __FUNCTION__, name);
- len = sizeof(buf) - 1;
- }
- write(atrace_marker_fd, buf, len);
+ WRITE_MSG("B|%d|", "%s", name, "");
}
void atrace_end_body()
{
- char c = 'E';
- write(atrace_marker_fd, &c, 1);
-}
-
-#define WRITE_MSG(format_begin, format_end, pid, name, value) { \
- char buf[ATRACE_MESSAGE_LENGTH]; \
- 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); \
+ WRITE_MSG("E|%d", "%s", "", "");
}
void atrace_async_begin_body(const char* name, int32_t cookie)
{
- WRITE_MSG("S|%d|", "|%" PRId32, getpid(), name, cookie);
+ WRITE_MSG("S|%d|", "|%" PRId32, name, cookie);
}
void atrace_async_end_body(const char* name, int32_t cookie)
{
- WRITE_MSG("F|%d|", "|%" PRId32, getpid(), name, cookie);
+ WRITE_MSG("F|%d|", "|%" PRId32, name, cookie);
}
void atrace_int_body(const char* name, int32_t value)
{
- WRITE_MSG("C|%d|", "|%" PRId32, getpid(), name, value);
+ WRITE_MSG("C|%d|", "|%" PRId32, name, value);
}
void atrace_int64_body(const char* name, int64_t value)
{
- WRITE_MSG("C|%d|", "|%" PRId64, getpid(), name, value);
+ WRITE_MSG("C|%d|", "|%" PRId64, name, value);
}