diff --git a/minzip/SysUtil.cpp b/minzip/SysUtil.cpp
new file mode 100644
index 0000000..4cdd60d
--- /dev/null
+++ b/minzip/SysUtil.cpp
@@ -0,0 +1,212 @@
+/*
+ * Copyright 2006 The Android Open Source Project
+ *
+ * System utilities.
+ */
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <android-base/logging.h>
+
+#include "SysUtil.h"
+
+static bool sysMapFD(int fd, MemMapping* pMap) {
+    assert(pMap != NULL);
+
+    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;
+    }
+
+    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;
+
+    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;
+
+    if (fgets(block_dev, sizeof(block_dev), mapf) == NULL) {
+        PLOG(ERROR) << "failed to read block device from header";
+        return -1;
+    }
+    for (i = 0; i < sizeof(block_dev); ++i) {
+        if (block_dev[i] == '\n') {
+            block_dev[i] = 0;
+            break;
+        }
+    }
+
+    if (fscanf(mapf, "%zu %u\n%u\n", &size, &blksize, &range_count) != 3) {
+        LOG(ERROR) << "failed to parse block map header";
+        return -1;
+    }
+    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->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;
+    }
+
+    // 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;
+    }
+
+    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;
+    }
+
+    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;
+}
+
+int sysMapFile(const char* fn, MemMapping* pMap)
+{
+    memset(pMap, 0, sizeof(*pMap));
+
+    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;
+        }
+
+        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);
+    }
+    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";
+        }
+    }
+    free(pMap->ranges);
+    pMap->ranges = NULL;
+    pMap->range_count = 0;
+}