Initial Contribution

1 files changed, 222 insertions, 0 deletions

diff --git a/include/utils/ZipFileRO.h b/include/utils/ZipFileRO.h
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+/*
+ * Copyright (C) 2007 The Android Open Source Project
+ *
+ * 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.
+ */
+
+//
+// Read-only access to Zip archives, with minimal heap allocation.
+//
+// This is similar to the more-complete ZipFile class, but no attempt
+// has been made to make them interchangeable.  This class operates under
+// a very different set of assumptions and constraints.
+//
+#ifndef __LIBS_ZIPFILERO_H
+#define __LIBS_ZIPFILERO_H
+
+#include "Errors.h"
+#include "FileMap.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+namespace android {
+
+/*
+ * Trivial typedef to ensure that ZipEntryRO is not treated as a simple
+ * integer.  We use NULL to indicate an invalid value.
+ */
+typedef void* ZipEntryRO;
+
+/*
+ * Open a Zip archive for reading.
+ *
+ * We want "open" and "find entry by name" to be fast operations, and we
+ * want to use as little memory as possible.  We memory-map the file,
+ * and load a hash table with pointers to the filenames (which aren't
+ * null-terminated).  The other fields are at a fixed offset from the
+ * filename, so we don't need to extract those (but we do need to byte-read
+ * and endian-swap them every time we want them).
+ *
+ * To speed comparisons when doing a lookup by name, we could make the mapping
+ * "private" (copy-on-write) and null-terminate the filenames after verifying
+ * the record structure.  However, this requires a private mapping of
+ * every page that the Central Directory touches.  Easier to tuck a copy
+ * of the string length into the hash table entry.
+ */
+class ZipFileRO {
+public:
+    ZipFileRO()
+        : mFd(-1), mFileMap(NULL), mHashTableSize(-1), mHashTable(NULL)
+        {}
+    ~ZipFileRO() {
+        free(mHashTable);
+        if (mFileMap)
+            mFileMap->release();
+        if (mFd >= 0)
+            close(mFd);
+    }
+
+    /*
+     * Open an archive.
+     */
+    status_t open(const char* zipFileName);
+
+    /*
+     * Find an entry, by name.  Returns the entry identifier, or NULL if
+     * not found.
+     *
+     * If two entries have the same name, one will be chosen at semi-random.
+     */
+    ZipEntryRO findEntryByName(const char* fileName) const;
+
+    /*
+     * Return the #of entries in the Zip archive.
+     */
+    int getNumEntries(void) const {
+        return mNumEntries;
+    }
+
+    /*
+     * Return the Nth entry.  Zip file entries are not stored in sorted
+     * order, and updated entries may appear at the end, so anyone walking
+     * the archive needs to avoid making ordering assumptions.  We take
+     * that further by returning the Nth non-empty entry in the hash table
+     * rather than the Nth entry in the archive.
+     *
+     * Valid values are [0..numEntries).
+     *
+     * [This is currently O(n).  If it needs to be fast we can allocate an
+     * additional data structure or provide an iterator interface.]
+     */
+    ZipEntryRO findEntryByIndex(int idx) const;
+
+    /*
+     * Copy the filename into the supplied buffer.  Returns 0 on success,
+     * -1 if "entry" is invalid, or the filename length if it didn't fit.  The
+     * length, and the returned string, include the null-termination.
+     */
+    int getEntryFileName(ZipEntryRO entry, char* buffer, int bufLen) const;
+
+    /*
+     * Get the vital stats for an entry.  Pass in NULL pointers for anything
+     * you don't need.
+     *
+     * "*pOffset" holds the Zip file offset of the entry's data.
+     *
+     * Returns "false" if "entry" is bogus or if the data in the Zip file
+     * appears to be bad.
+     */
+    bool getEntryInfo(ZipEntryRO entry, int* pMethod, long* pUncompLen,
+        long* pCompLen, off_t* pOffset, long* pModWhen, long* pCrc32) const;
+
+    /*
+     * Create a new FileMap object that maps a subset of the archive.  For
+     * an uncompressed entry this effectively provides a pointer to the
+     * actual data, for a compressed entry this provides the input buffer
+     * for inflate().
+     */
+    FileMap* createEntryFileMap(ZipEntryRO entry) const;
+
+    /*
+     * Uncompress the data into a buffer.  Depending on the compression
+     * format, this is either an "inflate" operation or a memcpy.
+     *
+     * Use "uncompLen" from getEntryInfo() to determine the required
+     * buffer size.
+     *
+     * Returns "true" on success.
+     */
+    bool uncompressEntry(ZipEntryRO entry, void* buffer) const;
+
+    /*
+     * Uncompress the data to an open file descriptor.
+     */
+    bool uncompressEntry(ZipEntryRO entry, int fd) const;
+
+    /* Zip compression methods we support */
+    enum {
+        kCompressStored     = 0,        // no compression
+        kCompressDeflated   = 8,        // standard deflate
+    };
+
+    /*
+     * Utility function: uncompress deflated data, buffer to buffer.
+     */
+    static bool inflateBuffer(void* outBuf, const void* inBuf,
+        long uncompLen, long compLen);
+
+    /*
+     * Utility function: uncompress deflated data, buffer to fd.
+     */
+    static bool inflateBuffer(int fd, const void* inBuf,
+        long uncompLen, long compLen);
+
+    /*
+     * Some basic functions for raw data manipulation.  "LE" means
+     * Little Endian.
+     */
+    static inline unsigned short get2LE(const unsigned char* buf) {
+        return buf[0] | (buf[1] << 8);
+    }
+    static inline unsigned long get4LE(const unsigned char* buf) {
+        return buf[0] | (buf[1] << 8) | (buf[2] << 16) | (buf[3] << 24);
+    }
+
+private:
+    /* these are private and not defined */ 
+    ZipFileRO(const ZipFileRO& src);
+    ZipFileRO& operator=(const ZipFileRO& src);
+
+    /* parse the archive, prepping internal structures */
+    bool parseZipArchive(void);
+
+    /* add a new entry to the hash table */
+    void addToHash(const char* str, int strLen, unsigned int hash);
+
+    /* compute string hash code */
+    static unsigned int computeHash(const char* str, int len);
+
+    /* convert a ZipEntryRO back to a hash table index */
+    int entryToIndex(const ZipEntryRO entry) const;
+
+    /*
+     * One entry in the hash table.
+     */
+    typedef struct HashEntry {
+        const char*     name;
+        unsigned short  nameLen;
+        //unsigned int    hash;
+    } HashEntry;
+
+    /* open Zip archive */
+    int         mFd;
+
+    /* mapped file */
+    FileMap*    mFileMap;
+
+    /* number of entries in the Zip archive */
+    int         mNumEntries;
+
+    /*
+     * We know how many entries are in the Zip archive, so we have a
+     * fixed-size hash table.  We probe for an empty slot.
+     */
+    int         mHashTableSize;
+    HashEntry*  mHashTable;
+};
+
+}; // namespace android
+
+#endif /*__LIBS_ZIPFILERO_H*/