From 2d7f5c2dfc62a9b9e09144079e103dc0ac761224 Mon Sep 17 00:00:00 2001
From: Primiano Tucci <primiano@google.com>
Date: Thu, 17 Jan 2019 15:51:14 +0000
Subject: Remove ftrace dumping from dumpstate

When capturing a bug report, dumpstate checks if ftrace
is on, and if so, steals the trace from the buffer.
This feature doesn't seem to be actually used, getting
rid of unnecessary complexity and unnecessary permissions.
Furthermore, stealing the trace is bad for iorapd, studio
perfetto, Traceur and all the other trace users.
Matching selinux change: aosp/875395

Bug: 122987614
Test: run dumpstate before and after patch,
      file sizes are comparable,
      observed no tracing-related errors.
Change-Id: I8bcd478c9bde776a2ec21b5e9a97aedaaa3681fd
---
 cmds/dumpstate/dumpstate.cpp | 49 ++------------------------------------------
 1 file changed, 2 insertions(+), 47 deletions(-)

diff --git a/cmds/dumpstate/dumpstate.cpp b/cmds/dumpstate/dumpstate.cpp
index a45775a289..2824c82db1 100644
--- a/cmds/dumpstate/dumpstate.cpp
+++ b/cmds/dumpstate/dumpstate.cpp
@@ -475,47 +475,6 @@ static bool dump_anrd_trace() {
     return false;
 }
 
-static void dump_systrace() {
-    if (!ds.IsZipping()) {
-        MYLOGD("Not dumping systrace because it's not a zipped bugreport\n");
-        return;
-    }
-    std::string systrace_path = ds.GetPath("-systrace.txt");
-    if (systrace_path.empty()) {
-        MYLOGE("Not dumping systrace because path is empty\n");
-        return;
-    }
-    const char* path = "/sys/kernel/debug/tracing/tracing_on";
-    long int is_tracing;
-    if (read_file_as_long(path, &is_tracing)) {
-        return; // error already logged
-    }
-    if (is_tracing <= 0) {
-        MYLOGD("Skipping systrace because '%s' content is '%ld'\n", path, is_tracing);
-        return;
-    }
-
-    MYLOGD("Running '/system/bin/atrace --async_dump -o %s', which can take several minutes",
-            systrace_path.c_str());
-    if (RunCommand("SYSTRACE", {"/system/bin/atrace", "--async_dump", "-o", systrace_path},
-                   CommandOptions::WithTimeout(120).Build())) {
-        MYLOGE("systrace timed out, its zip entry will be incomplete\n");
-        // TODO: RunCommand tries to kill the process, but atrace doesn't die
-        // peacefully; ideally, we should call strace to stop itself, but there is no such option
-        // yet (just a --async_stop, which stops and dump
-        // if (RunCommand("SYSTRACE", {"/system/bin/atrace", "--kill"})) {
-        //   MYLOGE("could not stop systrace ");
-        // }
-    }
-    if (!ds.AddZipEntry("systrace.txt", systrace_path)) {
-        MYLOGE("Unable to add systrace file %s to zip file\n", systrace_path.c_str());
-    } else {
-        if (remove(systrace_path.c_str())) {
-            MYLOGE("Error removing systrace file %s: %s", systrace_path.c_str(), strerror(errno));
-        }
-    }
-}
-
 static bool skip_not_stat(const char *path) {
     static const char stat[] = "/stat";
     size_t len = strlen(path);
@@ -1440,12 +1399,8 @@ static void dumpstate() {
 
 /* Dumps state for the default case. Returns true if everything went fine. */
 static bool DumpstateDefault() {
-    // Dumps systrace right away, otherwise it will be filled with unnecessary events.
-    // First try to dump anrd trace if the daemon is running. Otherwise, dump
-    // the raw trace.
-    if (!dump_anrd_trace()) {
-        dump_systrace();
-    }
+    // Try to dump anrd trace if the daemon is running.
+    dump_anrd_trace();
 
     // Invoking the following dumpsys calls before dump_traces() to try and
     // keep the system stats as close to its initial state as possible.
-- 
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