diff --git a/debuggerd/tombstone.cpp b/debuggerd/tombstone.cpp
index fa983fa..dfdf29c 100644
--- a/debuggerd/tombstone.cpp
+++ b/debuggerd/tombstone.cpp
@@ -368,6 +368,7 @@
     ALOGE("Cannot get siginfo for %d: %s\n", tid, strerror(errno));
   }
 
+  ScopedBacktraceMapIteratorLock lock(map);
   _LOG(log, logtype::MAPS, "\n");
   if (!print_fault_address_marker) {
     _LOG(log, logtype::MAPS, "memory map:\n");
diff --git a/healthd/Android.mk b/healthd/Android.mk
index 127f39e..deebed5 100644
--- a/healthd/Android.mk
+++ b/healthd/Android.mk
@@ -17,7 +17,7 @@
 LOCAL_MODULE := libbatterymonitor
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
-LOCAL_STATIC_LIBRARIES := libutils libbinder
+LOCAL_STATIC_LIBRARIES := libutils libbase libbinder
 include $(BUILD_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
@@ -60,7 +60,7 @@
 
 LOCAL_C_INCLUDES := bootable/recovery $(LOCAL_PATH)/include
 
-LOCAL_STATIC_LIBRARIES := libbatterymonitor libbatteryservice libbinder
+LOCAL_STATIC_LIBRARIES := libbatterymonitor libbatteryservice libbinder libbase
 
 ifneq ($(strip $(LOCAL_CHARGER_NO_UI)),true)
 LOCAL_STATIC_LIBRARIES += libminui libpng libz
diff --git a/healthd/BatteryMonitor.cpp b/healthd/BatteryMonitor.cpp
index 69647de..d1c547d 100644
--- a/healthd/BatteryMonitor.cpp
+++ b/healthd/BatteryMonitor.cpp
@@ -28,6 +28,8 @@
 #include <unistd.h>
 #include <memory>
 
+#include <android-base/file.h>
+#include <android-base/strings.h>
 #include <batteryservice/BatteryService.h>
 #include <cutils/klog.h>
 #include <cutils/properties.h>
@@ -121,34 +123,15 @@
     return ret;
 }
 
-int BatteryMonitor::readFromFile(const String8& path, char* buf, size_t size) {
-    char *cp = NULL;
-
-    if (path.isEmpty())
-        return -1;
-    int fd = open(path.string(), O_RDONLY, 0);
-    if (fd == -1) {
-        KLOG_ERROR(LOG_TAG, "Could not open '%s'\n", path.string());
-        return -1;
+int BatteryMonitor::readFromFile(const String8& path, std::string* buf) {
+    if (android::base::ReadFileToString(String8::std_string(path), buf)) {
+        *buf = android::base::Trim(*buf);
     }
-
-    ssize_t count = TEMP_FAILURE_RETRY(read(fd, buf, size));
-    if (count > 0)
-            cp = (char *)memrchr(buf, '\n', count);
-
-    if (cp)
-        *cp = '\0';
-    else
-        buf[0] = '\0';
-
-    close(fd);
-    return count;
+    return buf->length();
 }
 
 BatteryMonitor::PowerSupplyType BatteryMonitor::readPowerSupplyType(const String8& path) {
-    const int SIZE = 128;
-    char buf[SIZE];
-    int length = readFromFile(path, buf, SIZE);
+    std::string buf;
     BatteryMonitor::PowerSupplyType ret;
     struct sysfsStringEnumMap supplyTypeMap[] = {
             { "Unknown", ANDROID_POWER_SUPPLY_TYPE_UNKNOWN },
@@ -167,12 +150,12 @@
             { NULL, 0 },
     };
 
-    if (length <= 0)
+    if (readFromFile(path, &buf) <= 0)
         return ANDROID_POWER_SUPPLY_TYPE_UNKNOWN;
 
-    ret = (BatteryMonitor::PowerSupplyType)mapSysfsString(buf, supplyTypeMap);
+    ret = (BatteryMonitor::PowerSupplyType)mapSysfsString(buf.c_str(), supplyTypeMap);
     if (ret < 0) {
-        KLOG_WARNING(LOG_TAG, "Unknown power supply type '%s'\n", buf);
+        KLOG_WARNING(LOG_TAG, "Unknown power supply type '%s'\n", buf.c_str());
         ret = ANDROID_POWER_SUPPLY_TYPE_UNKNOWN;
     }
 
@@ -180,27 +163,23 @@
 }
 
 bool BatteryMonitor::getBooleanField(const String8& path) {
-    const int SIZE = 16;
-    char buf[SIZE];
-
+    std::string buf;
     bool value = false;
-    if (readFromFile(path, buf, SIZE) > 0) {
-        if (buf[0] != '0') {
+
+    if (readFromFile(path, &buf) > 0)
+        if (buf[0] != '0')
             value = true;
-        }
-    }
 
     return value;
 }
 
 int BatteryMonitor::getIntField(const String8& path) {
-    const int SIZE = 128;
-    char buf[SIZE];
-
+    std::string buf;
     int value = 0;
-    if (readFromFile(path, buf, SIZE) > 0) {
-        value = strtol(buf, NULL, 0);
-    }
+
+    if (readFromFile(path, &buf) > 0)
+        value = std::stoi(buf.c_str(), NULL, 0);
+
     return value;
 }
 
@@ -241,18 +220,16 @@
         props.batteryHealth = BATTERY_HEALTH_GOOD;
     }
 
-    const int SIZE = 128;
-    char buf[SIZE];
-    String8 btech;
+    std::string buf;
 
-    if (readFromFile(mHealthdConfig->batteryStatusPath, buf, SIZE) > 0)
-        props.batteryStatus = getBatteryStatus(buf);
+    if (readFromFile(mHealthdConfig->batteryStatusPath, &buf) > 0)
+        props.batteryStatus = getBatteryStatus(buf.c_str());
 
-    if (readFromFile(mHealthdConfig->batteryHealthPath, buf, SIZE) > 0)
-        props.batteryHealth = getBatteryHealth(buf);
+    if (readFromFile(mHealthdConfig->batteryHealthPath, &buf) > 0)
+        props.batteryHealth = getBatteryHealth(buf.c_str());
 
-    if (readFromFile(mHealthdConfig->batteryTechnologyPath, buf, SIZE) > 0)
-        props.batteryTechnology = String8(buf);
+    if (readFromFile(mHealthdConfig->batteryTechnologyPath, &buf) > 0)
+        props.batteryTechnology = String8(buf.c_str());
 
     unsigned int i;
 
@@ -261,33 +238,31 @@
         path.appendFormat("%s/%s/online", POWER_SUPPLY_SYSFS_PATH,
                           mChargerNames[i].string());
 
-        if (readFromFile(path, buf, SIZE) > 0) {
-            if (buf[0] != '0') {
-                path.clear();
-                path.appendFormat("%s/%s/type", POWER_SUPPLY_SYSFS_PATH,
-                                  mChargerNames[i].string());
-                switch(readPowerSupplyType(path)) {
-                case ANDROID_POWER_SUPPLY_TYPE_AC:
-                    props.chargerAcOnline = true;
-                    break;
-                case ANDROID_POWER_SUPPLY_TYPE_USB:
-                    props.chargerUsbOnline = true;
-                    break;
-                case ANDROID_POWER_SUPPLY_TYPE_WIRELESS:
-                    props.chargerWirelessOnline = true;
-                    break;
-                default:
-                    KLOG_WARNING(LOG_TAG, "%s: Unknown power supply type\n",
-                                 mChargerNames[i].string());
-                }
-                path.clear();
-                path.appendFormat("%s/%s/current_max", POWER_SUPPLY_SYSFS_PATH,
-                                  mChargerNames[i].string());
-                if (access(path.string(), R_OK) == 0) {
-                    int maxChargingCurrent = getIntField(path);
-                    if (props.maxChargingCurrent < maxChargingCurrent) {
-                        props.maxChargingCurrent = maxChargingCurrent;
-                    }
+        if (getIntField(path)) {
+            path.clear();
+            path.appendFormat("%s/%s/type", POWER_SUPPLY_SYSFS_PATH,
+                              mChargerNames[i].string());
+            switch(readPowerSupplyType(path)) {
+            case ANDROID_POWER_SUPPLY_TYPE_AC:
+                props.chargerAcOnline = true;
+                break;
+            case ANDROID_POWER_SUPPLY_TYPE_USB:
+                props.chargerUsbOnline = true;
+                break;
+            case ANDROID_POWER_SUPPLY_TYPE_WIRELESS:
+                props.chargerWirelessOnline = true;
+                break;
+            default:
+                KLOG_WARNING(LOG_TAG, "%s: Unknown power supply type\n",
+                             mChargerNames[i].string());
+            }
+            path.clear();
+            path.appendFormat("%s/%s/current_max", POWER_SUPPLY_SYSFS_PATH,
+                              mChargerNames[i].string());
+            if (access(path.string(), R_OK) == 0) {
+                int maxChargingCurrent = getIntField(path);
+                if (props.maxChargingCurrent < maxChargingCurrent) {
+                    props.maxChargingCurrent = maxChargingCurrent;
                 }
             }
         }
@@ -343,10 +318,9 @@
 int BatteryMonitor::getChargeStatus() {
     int result = BATTERY_STATUS_UNKNOWN;
     if (!mHealthdConfig->batteryStatusPath.isEmpty()) {
-        char buf[128];
-        if (readFromFile(mHealthdConfig->batteryStatusPath, buf, sizeof(buf)) > 0) {
-            result = getBatteryStatus(buf);
-        }
+        std::string buf;
+        if (readFromFile(mHealthdConfig->batteryStatusPath, &buf) > 0)
+            result = getBatteryStatus(buf.c_str());
     }
     return result;
 }
diff --git a/healthd/include/healthd/BatteryMonitor.h b/healthd/include/healthd/BatteryMonitor.h
index 440f2e4..8865a7d 100644
--- a/healthd/include/healthd/BatteryMonitor.h
+++ b/healthd/include/healthd/BatteryMonitor.h
@@ -55,7 +55,7 @@
 
     int getBatteryStatus(const char* status);
     int getBatteryHealth(const char* status);
-    int readFromFile(const String8& path, char* buf, size_t size);
+    int readFromFile(const String8& path, std::string* buf);
     PowerSupplyType readPowerSupplyType(const String8& path);
     bool getBooleanField(const String8& path);
     int getIntField(const String8& path);
diff --git a/include/backtrace/BacktraceMap.h b/include/backtrace/BacktraceMap.h
index 2373c45..b80045f 100644
--- a/include/backtrace/BacktraceMap.h
+++ b/include/backtrace/BacktraceMap.h
@@ -71,6 +71,12 @@
   bool IsWritable(uintptr_t pc) { return GetFlags(pc) & PROT_WRITE; }
   bool IsExecutable(uintptr_t pc) { return GetFlags(pc) & PROT_EXEC; }
 
+  // In order to use the iterators on this object, a caller must
+  // call the LockIterator and UnlockIterator function to guarantee
+  // that the data does not change while it's being used.
+  virtual void LockIterator() {}
+  virtual void UnlockIterator() {}
+
   typedef std::deque<backtrace_map_t>::iterator iterator;
   iterator begin() { return maps_.begin(); }
   iterator end() { return maps_.end(); }
@@ -102,4 +108,18 @@
   pid_t pid_;
 };
 
+class ScopedBacktraceMapIteratorLock {
+public:
+  explicit ScopedBacktraceMapIteratorLock(BacktraceMap* map) : map_(map) {
+    map->LockIterator();
+  }
+
+  ~ScopedBacktraceMapIteratorLock() {
+    map_->UnlockIterator();
+  }
+
+private:
+  BacktraceMap* map_;
+};
+
 #endif // _BACKTRACE_BACKTRACE_MAP_H
diff --git a/libbacktrace/BacktraceMap.cpp b/libbacktrace/BacktraceMap.cpp
index 19551dc..00c35b1 100644
--- a/libbacktrace/BacktraceMap.cpp
+++ b/libbacktrace/BacktraceMap.cpp
@@ -36,8 +36,8 @@
 }
 
 void BacktraceMap::FillIn(uintptr_t addr, backtrace_map_t* map) {
-  for (BacktraceMap::const_iterator it = begin();
-       it != end(); ++it) {
+  ScopedBacktraceMapIteratorLock lock(this);
+  for (BacktraceMap::const_iterator it = begin(); it != end(); ++it) {
     if (addr >= it->start && addr < it->end) {
       *map = *it;
       return;
diff --git a/libbacktrace/UnwindMap.cpp b/libbacktrace/UnwindMap.cpp
index 34d79f9..af79562 100644
--- a/libbacktrace/UnwindMap.cpp
+++ b/libbacktrace/UnwindMap.cpp
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include <pthread.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <sys/types.h>
@@ -72,6 +73,7 @@
 }
 
 UnwindMapLocal::UnwindMapLocal() : UnwindMap(getpid()), map_created_(false) {
+  pthread_rwlock_init(&map_lock_, nullptr);
 }
 
 UnwindMapLocal::~UnwindMapLocal() {
@@ -82,9 +84,14 @@
 }
 
 bool UnwindMapLocal::GenerateMap() {
+  // Lock so that multiple threads cannot modify the maps data at the
+  // same time.
+  pthread_rwlock_wrlock(&map_lock_);
+
   // It's possible for the map to be regenerated while this loop is occurring.
   // If that happens, get the map again, but only try at most three times
   // before giving up.
+  bool generated = false;
   for (int i = 0; i < 3; i++) {
     maps_.clear();
 
@@ -110,12 +117,17 @@
     }
     // Check to see if the map changed while getting the data.
     if (ret != -UNW_EINVAL) {
-      return true;
+      generated = true;
+      break;
     }
   }
 
-  BACK_LOGW("Unable to generate the map.");
-  return false;
+  pthread_rwlock_unlock(&map_lock_);
+
+  if (!generated) {
+    BACK_LOGW("Unable to generate the map.");
+  }
+  return generated;
 }
 
 bool UnwindMapLocal::Build() {
diff --git a/libbacktrace/UnwindMap.h b/libbacktrace/UnwindMap.h
index 111401f..f85b54a 100644
--- a/libbacktrace/UnwindMap.h
+++ b/libbacktrace/UnwindMap.h
@@ -17,6 +17,7 @@
 #ifndef _LIBBACKTRACE_UNWIND_MAP_H
 #define _LIBBACKTRACE_UNWIND_MAP_H
 
+#include <pthread.h>
 #include <stdint.h>
 #include <sys/types.h>
 
@@ -56,10 +57,15 @@
 
   void FillIn(uintptr_t addr, backtrace_map_t* map) override;
 
+  void LockIterator() override { pthread_rwlock_rdlock(&map_lock_); }
+  void UnlockIterator() override { pthread_rwlock_unlock(&map_lock_); }
+
 private:
   bool GenerateMap();
 
   bool map_created_;
+
+  pthread_rwlock_t map_lock_;
 };
 
 #endif // _LIBBACKTRACE_UNWIND_MAP_H
diff --git a/libbacktrace/backtrace_test.cpp b/libbacktrace/backtrace_test.cpp
index 7066c79..e25c8e9 100644
--- a/libbacktrace/backtrace_test.cpp
+++ b/libbacktrace/backtrace_test.cpp
@@ -895,6 +895,7 @@
   std::unique_ptr<BacktraceMap> map(BacktraceMap::Create(pid));
 
   // Basic test that verifies that the map is in the expected order.
+  ScopedBacktraceMapIteratorLock lock(map.get());
   std::vector<map_test_t>::const_iterator test_it = test_maps.begin();
   for (BacktraceMap::const_iterator it = map->begin(); it != map->end(); ++it) {
     ASSERT_TRUE(test_it != test_maps.end());