[sanitizer] VReport thread status for failed PTRACE_ATTACH

compiler-rt/lib/asan/asan_posix.cpp

@@ -149,6 +149,7 @@ void PlatformTSDDtor(void *tsd) {
 #  endif
 
 static void BeforeFork() {
+  VReport(2, "BeforeFork tid: %d\n", GetTid());
   if (CAN_SANITIZE_LEAKS) {
     __lsan::LockGlobal();
   }
@@ -168,6 +169,7 @@ static void AfterFork(bool fork_child) {
   if (CAN_SANITIZE_LEAKS) {
     __lsan::UnlockGlobal();
   }
+  VReport(2, "AfterFork tid: %d\n", GetTid());
 }
 
 void InstallAtForkHandler() {

compiler-rt/lib/dfsan/dfsan_custom.cpp

@@ -2859,13 +2859,15 @@ WRAPPER_ALIAS(__isoc99_sscanf, sscanf)
 WRAPPER_ALIAS(__isoc23_sscanf, sscanf)
 
 static void BeforeFork() {
+  VReport(2, "BeforeFork tid: %d\n", GetTid());
   StackDepotLockBeforeFork();
   ChainedOriginDepotLockBeforeFork();
 }
 
 static void AfterFork(bool fork_child) {
   ChainedOriginDepotUnlockAfterFork(fork_child);
   StackDepotUnlockAfterFork(fork_child);
+  VReport(2, "AfterFork tid: %d\n", GetTid());
 }
 
 SANITIZER_INTERFACE_ATTRIBUTE

compiler-rt/lib/hwasan/hwasan_linux.cpp

@@ -528,6 +528,7 @@ uptr TagMemoryAligned(uptr p, uptr size, tag_t tag) {
 }
 
 static void BeforeFork() {
+  VReport(2, "BeforeFork tid: %d\n", GetTid());
   if (CAN_SANITIZE_LEAKS) {
     __lsan::LockGlobal();
   }
@@ -547,6 +548,7 @@ static void AfterFork(bool fork_child) {
   if (CAN_SANITIZE_LEAKS) {
     __lsan::UnlockGlobal();
   }
+  VReport(2, "AfterFork tid: %d\n", GetTid());
 }
 
 void HwasanInstallAtForkHandler() {

compiler-rt/lib/lsan/lsan_posix.cpp

@@ -97,6 +97,7 @@ void InstallAtExitCheckLeaks() {
 }
 
 static void BeforeFork() {
+  VReport(2, "BeforeFork tid: %d\n", GetTid());
   LockGlobal();
   LockThreads();
   LockAllocator();
@@ -108,6 +109,7 @@ static void AfterFork(bool fork_child) {
   UnlockAllocator();
   UnlockThreads();
   UnlockGlobal();
+  VReport(2, "AfterFork tid: %d\n", GetTid());
 }
 
 void InstallAtForkHandler() {

compiler-rt/lib/msan/msan_linux.cpp

@@ -302,6 +302,7 @@ void MsanTSDDtor(void *tsd) {
 #  endif
 
 static void BeforeFork() {
+  VReport(2, "BeforeFork tid: %d\n", GetTid());
   // Usually we lock ThreadRegistry, but msan does not have one.
   LockAllocator();
   StackDepotLockBeforeFork();
@@ -313,6 +314,7 @@ static void AfterFork(bool fork_child) {
   StackDepotUnlockAfterFork(fork_child);
   UnlockAllocator();
   // Usually we unlock ThreadRegistry, but msan does not have one.
+  VReport(2, "AfterFork tid: %d\n", GetTid());
 }
 
 void InstallAtForkHandler() {

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

@@ -1025,21 +1025,21 @@ bool internal_sigismember(__sanitizer_sigset_t *set, int signum) {
 
 #  if !SANITIZER_NETBSD
 // ThreadLister implementation.
-ThreadLister::ThreadLister(pid_t pid) : pid_(pid), buffer_(4096) {
-  char task_directory_path[80];
-  internal_snprintf(task_directory_path, sizeof(task_directory_path),
-                    "/proc/%d/task/", pid);
-  descriptor_ = internal_open(task_directory_path, O_RDONLY | O_DIRECTORY);
-  if (internal_iserror(descriptor_)) {
-    Report("Can't open /proc/%d/task for reading.\n", pid);
-  }
+ThreadLister::ThreadLister(pid_t pid) : buffer_(4096) {
+  task_path_.AppendF("/proc/%d/task", pid);
+  status_path_.AppendF("%s/status", task_path_.data());
 }
 
 ThreadLister::Result ThreadLister::ListThreads(
     InternalMmapVector<tid_t> *threads) {
-  if (internal_iserror(descriptor_))
+  int descriptor = internal_open(task_path_.data(), O_RDONLY | O_DIRECTORY);
+  if (internal_iserror(descriptor)) {
+    Report("Can't open %s for reading.\n", task_path_.data());
     return Error;
-  internal_lseek(descriptor_, 0, SEEK_SET);
+  }
+  auto acts_cleanup = at_scope_exit([&] {
+    internal_close(descriptor);
+  });
   threads->clear();
 
   Result result = Ok;
@@ -1048,11 +1048,11 @@ ThreadLister::Result ThreadLister::ListThreads(
     buffer_.resize(buffer_.capacity());
     CHECK_GE(buffer_.size(), 4096);
     uptr read = internal_getdents(
-        descriptor_, (struct linux_dirent *)buffer_.data(), buffer_.size());
+        descriptor, (struct linux_dirent *)buffer_.data(), buffer_.size());
     if (!read)
       return result;
     if (internal_iserror(read)) {
-      Report("Can't read directory entries from /proc/%d/task.\n", pid_);
+      Report("Can't read directory entries from %s.\n", task_path_.data());
       return Error;
     }
 
@@ -1093,9 +1093,7 @@ ThreadLister::Result ThreadLister::ListThreads(
 bool ThreadLister::IsAlive(int tid) {
   // /proc/%d/task/%d/status uses same call to detect alive threads as
   // proc_task_readdir. See task_state implementation in Linux.
-  char path[80];
-  internal_snprintf(path, sizeof(path), "/proc/%d/task/%d/status", pid_, tid);
-  if (!ReadFileToVector(path, &buffer_) || buffer_.empty())
+  if (!ReadFileToVector(status_path_.data(), &buffer_) || buffer_.empty())
     return false;
   buffer_.push_back(0);
   static const char kPrefix[] = "\nPPid:";
@@ -1106,10 +1104,6 @@ bool ThreadLister::IsAlive(int tid) {
   return (int)internal_atoll(field) != 0;
 }
 
-ThreadLister::~ThreadLister() {
-  if (!internal_iserror(descriptor_))
-    internal_close(descriptor_);
-}
 #  endif
 
 #  if SANITIZER_WORDSIZE == 32

compiler-rt/lib/sanitizer_common/sanitizer_linux.h

@@ -97,7 +97,6 @@ uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg);
 class ThreadLister {
  public:
   explicit ThreadLister(pid_t pid);
-  ~ThreadLister();
   enum Result {
     Error,
     Incomplete,
@@ -108,8 +107,8 @@ class ThreadLister {
  private:
   bool IsAlive(int tid);
 
-  pid_t pid_;
-  int descriptor_ = -1;
+  InternalScopedString task_path_;
+  InternalScopedString status_path_;
   InternalMmapVector<char> buffer_;
 };
 

compiler-rt/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cpp

@@ -148,6 +148,14 @@ bool ThreadSuspender::SuspendThread(tid_t tid) {
     // Log this event and move on.
     VReport(1, "Could not attach to thread %zu (errno %d).\n", (uptr)tid,
             pterrno);
+    if (common_flags()->verbosity >= 2) {
+      InternalScopedString path;
+      path.AppendF("/proc/%d/task/%llu/status", pid_, tid);
+      InternalMmapVector<char> buffer;
+      ReadFileToVector(path.data(), &buffer);
+      buffer.push_back(0);
+      VReport(2, "%s: %s\n", path.data(), buffer.data());
+    }
     return false;
   } else {
     VReport(2, "Attached to thread %zu.\n", (uptr)tid);

compiler-rt/lib/tsan/rtl/tsan_rtl.cpp

@@ -806,6 +806,7 @@ int Finalize(ThreadState *thr) {
 
 #if !SANITIZER_GO
 void ForkBefore(ThreadState* thr, uptr pc) SANITIZER_NO_THREAD_SAFETY_ANALYSIS {
+  VReport(2, "BeforeFork tid: %d\n", GetTid());
   GlobalProcessorLock();
   // Detaching from the slot makes OnUserFree skip writing to the shadow.
   // The slot will be locked so any attempts to use it will deadlock anyway.
@@ -847,6 +848,7 @@ static void ForkAfter(ThreadState* thr,
   SlotAttachAndLock(thr);
   SlotUnlock(thr);
   GlobalProcessorUnlock();
+  VReport(2, "AfterFork tid: %d\n", GetTid());
 }
 
 void ForkParentAfter(ThreadState* thr, uptr pc) { ForkAfter(thr, false); }