diff --git a/otautil/SysUtil.cpp b/otautil/SysUtil.cpp
index efeb91c..5156514 100644
--- a/otautil/SysUtil.cpp
+++ b/otautil/SysUtil.cpp
@@ -1,13 +1,25 @@
 /*
  * Copyright 2006 The Android Open Source Project
  *
- * System utilities.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
  */
+
+#include "SysUtil.h"
+
 #include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
-#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -17,197 +29,190 @@
 #include <sys/types.h>
 #include <unistd.h>
 
-#include <android-base/logging.h>
+#include <algorithm>
+#include <string>
+#include <vector>
 
-#include "SysUtil.h"
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/strings.h>
+#include <android-base/unique_fd.h>
 
 static bool sysMapFD(int fd, MemMapping* pMap) {
-    assert(pMap != NULL);
+  CHECK(pMap != nullptr);
 
-    struct stat sb;
-    if (fstat(fd, &sb) == -1) {
-        PLOG(ERROR) << "fstat(" << fd << ") failed";
-        return false;
-    }
+  struct stat sb;
+  if (fstat(fd, &sb) == -1) {
+    PLOG(ERROR) << "fstat(" << fd << ") failed";
+    return false;
+  }
 
-    void* memPtr = mmap(NULL, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
-    if (memPtr == MAP_FAILED) {
-        PLOG(ERROR) << "mmap(" << sb.st_size << ", R, PRIVATE, " << fd << ", 0) failed";
-        return false;
-    }
+  void* memPtr = mmap(nullptr, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+  if (memPtr == MAP_FAILED) {
+    PLOG(ERROR) << "mmap(" << sb.st_size << ", R, PRIVATE, " << fd << ", 0) failed";
+    return false;
+  }
 
-    pMap->addr = reinterpret_cast<unsigned char*>(memPtr);
-    pMap->length = sb.st_size;
-    pMap->range_count = 1;
-    pMap->ranges = reinterpret_cast<MappedRange*>(malloc(sizeof(MappedRange)));
-    if (pMap->ranges == NULL) {
-        PLOG(ERROR) << "malloc failed";
-        munmap(memPtr, sb.st_size);
-        return false;
-    }
-    pMap->ranges[0].addr = memPtr;
-    pMap->ranges[0].length = sb.st_size;
+  pMap->addr = static_cast<unsigned char*>(memPtr);
+  pMap->length = sb.st_size;
+  pMap->ranges.push_back({ memPtr, static_cast<size_t>(sb.st_size) });
 
-    return true;
+  return true;
 }
 
-static int sysMapBlockFile(FILE* mapf, MemMapping* pMap)
-{
-    char block_dev[PATH_MAX+1];
-    size_t size;
-    unsigned int blksize;
-    size_t blocks;
-    unsigned int range_count;
-    unsigned int i;
+// A "block map" which looks like this (from uncrypt/uncrypt.cpp):
+//
+//     /dev/block/platform/msm_sdcc.1/by-name/userdata     # block device
+//     49652 4096                        # file size in bytes, block size
+//     3                                 # count of block ranges
+//     1000 1008                         # block range 0
+//     2100 2102                         # ... block range 1
+//     30 33                             # ... block range 2
+//
+// Each block range represents a half-open interval; the line "30 33"
+// reprents the blocks [30, 31, 32].
+static int sysMapBlockFile(const char* filename, MemMapping* pMap) {
+  CHECK(pMap != nullptr);
 
-    if (fgets(block_dev, sizeof(block_dev), mapf) == NULL) {
-        PLOG(ERROR) << "failed to read block device from header";
-        return -1;
+  std::string content;
+  if (!android::base::ReadFileToString(filename, &content)) {
+    PLOG(ERROR) << "Failed to read " << filename;
+    return -1;
+  }
+
+  std::vector<std::string> lines = android::base::Split(android::base::Trim(content), "\n");
+  if (lines.size() < 4) {
+    LOG(ERROR) << "Block map file is too short: " << lines.size();
+    return -1;
+  }
+
+  size_t size;
+  unsigned int blksize;
+  if (sscanf(lines[1].c_str(), "%zu %u", &size, &blksize) != 2) {
+    LOG(ERROR) << "Failed to parse file size and block size: " << lines[1];
+    return -1;
+  }
+
+  size_t range_count;
+  if (sscanf(lines[2].c_str(), "%zu", &range_count) != 1) {
+    LOG(ERROR) << "Failed to parse block map header: " << lines[2];
+    return -1;
+  }
+
+  size_t blocks;
+  if (blksize != 0) {
+    blocks = ((size - 1) / blksize) + 1;
+  }
+  if (size == 0 || blksize == 0 || blocks > SIZE_MAX / blksize || range_count == 0 ||
+      lines.size() != 3 + range_count) {
+    LOG(ERROR) << "Invalid data in block map file: size " << size << ", blksize " << blksize
+               << ", range_count " << range_count << ", lines " << lines.size();
+    return -1;
+  }
+
+  // Reserve enough contiguous address space for the whole file.
+  void* reserve = mmap64(nullptr, blocks * blksize, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
+  if (reserve == MAP_FAILED) {
+    PLOG(ERROR) << "failed to reserve address space";
+    return -1;
+  }
+
+  const std::string& block_dev = lines[0];
+  android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(block_dev.c_str(), O_RDONLY)));
+  if (fd == -1) {
+    PLOG(ERROR) << "failed to open block device " << block_dev;
+    munmap(reserve, blocks * blksize);
+    return -1;
+  }
+
+  pMap->ranges.resize(range_count);
+
+  unsigned char* next = static_cast<unsigned char*>(reserve);
+  size_t remaining_size = blocks * blksize;
+  bool success = true;
+  for (size_t i = 0; i < range_count; ++i) {
+    const std::string& line = lines[i + 3];
+
+    size_t start, end;
+    if (sscanf(line.c_str(), "%zu %zu\n", &start, &end) != 2) {
+      LOG(ERROR) << "failed to parse range " << i << " in block map: " << line;
+      success = false;
+      break;
     }
-    for (i = 0; i < sizeof(block_dev); ++i) {
-        if (block_dev[i] == '\n') {
-            block_dev[i] = 0;
-            break;
-        }
+    size_t length = (end - start) * blksize;
+    if (end <= start || (end - start) > SIZE_MAX / blksize || length > remaining_size) {
+      LOG(ERROR) << "unexpected range in block map: " << start << " " << end;
+      success = false;
+      break;
     }
 
-    if (fscanf(mapf, "%zu %u\n%u\n", &size, &blksize, &range_count) != 3) {
-        LOG(ERROR) << "failed to parse block map header";
-        return -1;
+    void* addr = mmap64(next, length, PROT_READ, MAP_PRIVATE | MAP_FIXED, fd,
+                        static_cast<off64_t>(start) * blksize);
+    if (addr == MAP_FAILED) {
+      PLOG(ERROR) << "failed to map block " << i;
+      success = false;
+      break;
     }
-    if (blksize != 0) {
-        blocks = ((size-1) / blksize) + 1;
-    }
-    if (size == 0 || blksize == 0 || blocks > SIZE_MAX / blksize || range_count == 0) {
-        LOG(ERROR) << "invalid data in block map file: size " << size << ", blksize " << blksize
-                   << ", range_count " << range_count;
-        return -1;
-    }
+    pMap->ranges[i].addr = addr;
+    pMap->ranges[i].length = length;
 
-    pMap->range_count = range_count;
-    pMap->ranges = reinterpret_cast<MappedRange*>(calloc(range_count, sizeof(MappedRange)));
-    if (pMap->ranges == NULL) {
-        PLOG(ERROR) << "calloc(" << range_count << ", " << sizeof(MappedRange) << ") failed";
-        return -1;
-    }
+    next += length;
+    remaining_size -= length;
+  }
+  if (success && remaining_size != 0) {
+    LOG(ERROR) << "ranges in block map are invalid: remaining_size = " << remaining_size;
+    success = false;
+  }
+  if (!success) {
+    munmap(reserve, blocks * blksize);
+    return -1;
+  }
 
-    // Reserve enough contiguous address space for the whole file.
-    unsigned char* reserve = reinterpret_cast<unsigned char*>(mmap64(NULL, blocks * blksize,
-            PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0));
-    if (reserve == MAP_FAILED) {
-        PLOG(ERROR) << "failed to reserve address space";
-        free(pMap->ranges);
-        return -1;
-    }
+  pMap->addr = static_cast<unsigned char*>(reserve);
+  pMap->length = size;
 
-    int fd = open(block_dev, O_RDONLY);
-    if (fd < 0) {
-        PLOG(ERROR) << "failed to open block device " << block_dev;
-        munmap(reserve, blocks * blksize);
-        free(pMap->ranges);
-        return -1;
-    }
+  LOG(INFO) << "mmapped " << range_count << " ranges";
 
-    unsigned char* next = reserve;
-    size_t remaining_size = blocks * blksize;
-    bool success = true;
-    for (i = 0; i < range_count; ++i) {
-        size_t start, end;
-        if (fscanf(mapf, "%zu %zu\n", &start, &end) != 2) {
-            LOG(ERROR) << "failed to parse range " << i << " in block map";
-            success = false;
-            break;
-        }
-        size_t length = (end - start) * blksize;
-        if (end <= start || ((end - start) > SIZE_MAX / blksize) || length > remaining_size) {
-            LOG(ERROR) << "unexpected range in block map: " << start << " " << end;
-            success = false;
-            break;
-        }
-
-        void* addr = mmap64(next, length, PROT_READ, MAP_PRIVATE | MAP_FIXED, fd, ((off64_t)(start*blksize)));
-        if (addr == MAP_FAILED) {
-            PLOG(ERROR) << "failed to map block " << i;
-            success = false;
-            break;
-        }
-        pMap->ranges[i].addr = addr;
-        pMap->ranges[i].length = length;
-
-        next += length;
-        remaining_size -= length;
-    }
-    if (success && remaining_size != 0) {
-        LOG(ERROR) << "ranges in block map are invalid: remaining_size = " << remaining_size;
-        success = false;
-    }
-    if (!success) {
-        close(fd);
-        munmap(reserve, blocks * blksize);
-        free(pMap->ranges);
-        return -1;
-    }
-
-    close(fd);
-    pMap->addr = reserve;
-    pMap->length = size;
-
-    LOG(INFO) << "mmapped " << range_count << " ranges";
-
-    return 0;
+  return 0;
 }
 
-int sysMapFile(const char* fn, MemMapping* pMap)
-{
-    memset(pMap, 0, sizeof(*pMap));
+int sysMapFile(const char* fn, MemMapping* pMap) {
+  if (fn == nullptr || pMap == nullptr) {
+    LOG(ERROR) << "Invalid argument(s)";
+    return -1;
+  }
 
-    if (fn && fn[0] == '@') {
-        // A map of blocks
-        FILE* mapf = fopen(fn+1, "r");
-        if (mapf == NULL) {
-            PLOG(ERROR) << "Unable to open '" << (fn+1) << "'";
-            return -1;
-        }
+  *pMap = {};
 
-        if (sysMapBlockFile(mapf, pMap) != 0) {
-            LOG(ERROR) << "Map of '" << fn << "' failed";
-            fclose(mapf);
-            return -1;
-        }
-
-        fclose(mapf);
-    } else {
-        // This is a regular file.
-        int fd = open(fn, O_RDONLY);
-        if (fd == -1) {
-            PLOG(ERROR) << "Unable to open '" << fn << "'";
-            return -1;
-        }
-
-        if (!sysMapFD(fd, pMap)) {
-            LOG(ERROR) << "Map of '" << fn << "' failed";
-            close(fd);
-            return -1;
-        }
-
-        close(fd);
+  if (fn[0] == '@') {
+    if (sysMapBlockFile(fn + 1, pMap) != 0) {
+      LOG(ERROR) << "Map of '" << fn << "' failed";
+      return -1;
     }
-    return 0;
+  } else {
+    // This is a regular file.
+    android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(fn, O_RDONLY)));
+    if (fd == -1) {
+      PLOG(ERROR) << "Unable to open '" << fn << "'";
+      return -1;
+    }
+
+    if (!sysMapFD(fd, pMap)) {
+      LOG(ERROR) << "Map of '" << fn << "' failed";
+      return -1;
+    }
+  }
+  return 0;
 }
 
 /*
  * Release a memory mapping.
  */
-void sysReleaseMap(MemMapping* pMap)
-{
-    int i;
-    for (i = 0; i < pMap->range_count; ++i) {
-        if (munmap(pMap->ranges[i].addr, pMap->ranges[i].length) < 0) {
-            PLOG(ERROR) << "munmap(" << pMap->ranges[i].addr << ", " << pMap->ranges[i].length
-                        << ") failed";
-        }
+void sysReleaseMap(MemMapping* pMap) {
+  std::for_each(pMap->ranges.cbegin(), pMap->ranges.cend(), [](const MappedRange& range) {
+    if (munmap(range.addr, range.length) == -1) {
+      PLOG(ERROR) << "munmap(" << range.addr << ", " << range.length << ") failed";
     }
-    free(pMap->ranges);
-    pMap->ranges = NULL;
-    pMap->range_count = 0;
+  });
+  pMap->ranges.clear();
 }
diff --git a/otautil/SysUtil.h b/otautil/SysUtil.h
index 7adff1e..6a79bf3 100644
--- a/otautil/SysUtil.h
+++ b/otautil/SysUtil.h
@@ -1,33 +1,40 @@
 /*
  * Copyright 2006 The Android Open Source Project
  *
- * System utilities.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
  */
-#ifndef _MINZIP_SYSUTIL
-#define _MINZIP_SYSUTIL
 
-#include <stdio.h>
+#ifndef _OTAUTIL_SYSUTIL
+#define _OTAUTIL_SYSUTIL
+
 #include <sys/types.h>
 
-#ifdef __cplusplus
-extern "C" {
-#endif
+#include <vector>
 
-typedef struct MappedRange {
-    void* addr;
-    size_t length;
-} MappedRange;
+struct MappedRange {
+  void* addr;
+  size_t length;
+};
 
 /*
  * Use this to keep track of mapped segments.
  */
-typedef struct MemMapping {
-    unsigned char* addr;           /* start of data */
-    size_t         length;         /* length of data */
+struct MemMapping {
+  unsigned char* addr; /* start of data */
+  size_t length;       /* length of data */
 
-    int            range_count;
-    MappedRange*   ranges;
-} MemMapping;
+  std::vector<MappedRange> ranges;
+};
 
 /*
  * Map a file into a private, read-only memory segment.  If 'fn'
@@ -45,8 +52,4 @@
  */
 void sysReleaseMap(MemMapping* pMap);
 
-#ifdef __cplusplus
-}
-#endif
-
-#endif /*_MINZIP_SYSUTIL*/
+#endif  // _OTAUTIL_SYSUTIL