[sancov] Fix map update logic on Android.

dlopen()/dlclose() are not interceptable on Android,
so we update .sancov.map in module constructor callbacks.

llvm-svn: 210098

1 files changed, 31 insertions, 28 deletions

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc b/compiler-rt/lib/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc
index e814c2e5e29..b3c8dc8916a 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc
@@ -37,22 +37,16 @@ namespace __sanitizer {
 
 static const uptr kMaxNumberOfModules = 1 << 14;
 
+static char *last_mapping;
+static StaticSpinMutex mapping_mu;
+
 void CovUpdateMapping() {
   if (!common_flags()->coverage || !common_flags()->coverage_direct) return;
 
-  int err;
-  InternalScopedString tmp_path(64 +
-                                internal_strlen(common_flags()->coverage_dir));
-  uptr res = internal_snprintf((char *)tmp_path.data(), tmp_path.size(),
-                    "%s/%zd.sancov.map.tmp", common_flags()->coverage_dir,
-                    internal_getpid());
-  CHECK_LE(res, tmp_path.size());
-  uptr map_fd = OpenFile(tmp_path.data(), true);
-  if (internal_iserror(map_fd)) {
-    Report(" Coverage: failed to open %s for writing\n", tmp_path.data());
-    Die();
-  }
+  SpinMutexLock l(&mapping_mu);
 
+  const uptr kMaxTextSize = 64 * 1024;
+  InternalScopedString text(kMaxTextSize);
   InternalScopedBuffer<char> modules_data(kMaxNumberOfModules *
                                           sizeof(LoadedModule));
   LoadedModule *modules = (LoadedModule *)modules_data.data();
@@ -60,31 +54,40 @@ void CovUpdateMapping() {
   int n_modules = GetListOfModules(modules, kMaxNumberOfModules,
                                    /* filter */ 0);
 
-  InternalScopedString line(4096);
-  line.append("%d\n", sizeof(uptr) * 8);
-  res = internal_write(map_fd, line.data(), line.length());
-  if (internal_iserror(res, &err)) {
-    Printf("sancov.map write failed: %d\n", err);
-    Die();
-  }
-  line.clear();
-
+  text.append("%d\n", sizeof(uptr) * 8);
   for (int i = 0; i < n_modules; ++i) {
     char *module_name = StripModuleName(modules[i].full_name());
     for (unsigned j = 0; j < modules[i].n_ranges(); ++j) {
-      line.append("%zx %zx %zx %s\n", modules[i].address_range_start(j),
+      text.append("%zx %zx %zx %s\n", modules[i].address_range_start(j),
                   modules[i].address_range_end(j), modules[i].base_address(),
                   module_name);
-      res = internal_write(map_fd, line.data(), line.length());
-      if (internal_iserror(res, &err)) {
-        Printf("sancov.map write failed: %d\n", err);
-        Die();
-      }
-      line.clear();
     }
     InternalFree(module_name);
   }
 
+  // Do not write mapping if it is the same as the one we've wrote last time.
+  if (last_mapping && (internal_strcmp(last_mapping, text.data()) == 0)) return;
+  if (!last_mapping) last_mapping = (char *)InternalAlloc(kMaxTextSize);
+  internal_strncpy(last_mapping, text.data(), kMaxTextSize);
+
+  int err;
+  InternalScopedString tmp_path(64 +
+                                internal_strlen(common_flags()->coverage_dir));
+  uptr res = internal_snprintf((char *)tmp_path.data(), tmp_path.size(),
+                    "%s/%zd.sancov.map.tmp", common_flags()->coverage_dir,
+                    internal_getpid());
+  CHECK_LE(res, tmp_path.size());
+  uptr map_fd = OpenFile(tmp_path.data(), true);
+  if (internal_iserror(map_fd)) {
+    Report(" Coverage: failed to open %s for writing\n", tmp_path.data());
+    Die();
+  }
+
+  res = internal_write(map_fd, text.data(), text.length());
+  if (internal_iserror(res, &err)) {
+    Printf("sancov.map write failed: %d\n", err);
+    Die();
+  }
   internal_close(map_fd);
 
   InternalScopedString path(64 + internal_strlen(common_flags()->coverage_dir));