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      1 /*
      2  * Copyright (C) 2006 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 //
     18 // Access to entries in a Zip archive.
     19 //
     20 
     21 #include "ZipEntry.h"
     22 
     23 #include <stdio.h>
     24 #include <string.h>
     25 #include <assert.h>
     26 #include <inttypes.h>
     27 
     28 using namespace android;
     29 
     30 #define LOG(...) fprintf(stderr, __VA_ARGS__)
     31 
     32 /* Jan 01 2008 */
     33 #define STATIC_DATE (28 << 9 | 1 << 5 | 1)
     34 #define STATIC_TIME 0
     35 
     36 /*
     37  * Initialize a new ZipEntry structure from a FILE* positioned at a
     38  * CentralDirectoryEntry. Rewrites the headers to remove the dynamic
     39  * timestamps.
     40  *
     41  * On exit, the file pointer will be at the start of the next CDE or
     42  * at the EOCD.
     43  */
     44 status_t ZipEntry::initAndRewriteFromCDE(FILE* fp)
     45 {
     46     status_t result;
     47     long posn;
     48 
     49     /* read the CDE */
     50     result = mCDE.rewrite(fp);
     51     if (result != 0) {
     52         LOG("mCDE.rewrite failed\n");
     53         return result;
     54     }
     55 
     56     /* using the info in the CDE, go load up the LFH */
     57     posn = ftell(fp);
     58     if (fseek(fp, mCDE.mLocalHeaderRelOffset, SEEK_SET) != 0) {
     59         LOG("local header seek failed (%" PRIu32 ")\n",
     60             mCDE.mLocalHeaderRelOffset);
     61         return -1;
     62     }
     63 
     64     result = mLFH.rewrite(fp);
     65     if (result != 0) {
     66         LOG("mLFH.rewrite failed\n");
     67         return result;
     68     }
     69 
     70     if (fseek(fp, posn, SEEK_SET) != 0)
     71         return -1;
     72 
     73     return 0;
     74 }
     75 
     76 /*
     77  * ===========================================================================
     78  *      ZipEntry::LocalFileHeader
     79  * ===========================================================================
     80  */
     81 
     82 /*
     83  * Rewrite a local file header.
     84  *
     85  * On entry, "fp" points to the signature at the start of the header.
     86  */
     87 status_t ZipEntry::LocalFileHeader::rewrite(FILE* fp)
     88 {
     89     uint8_t buf[kLFHLen];
     90 
     91     if (fread(buf, 1, kLFHLen, fp) != kLFHLen)
     92         return -1;
     93 
     94     if (ZipEntry::getLongLE(&buf[0x00]) != kSignature) {
     95         LOG("whoops: didn't find expected signature\n");
     96         return -1;
     97     }
     98 
     99     ZipEntry::putShortLE(&buf[0x0a], STATIC_TIME);
    100     ZipEntry::putShortLE(&buf[0x0c], STATIC_DATE);
    101 
    102     if (fseek(fp, -kLFHLen, SEEK_CUR) != 0)
    103         return -1;
    104 
    105     if (fwrite(buf, 1, kLFHLen, fp) != kLFHLen)
    106         return -1;
    107 
    108     return 0;
    109 }
    110 
    111 /*
    112  * ===========================================================================
    113  *      ZipEntry::CentralDirEntry
    114  * ===========================================================================
    115  */
    116 
    117 /*
    118  * Read and rewrite the central dir entry that appears next in the file.
    119  *
    120  * On entry, "fp" should be positioned on the signature bytes for the
    121  * entry.  On exit, "fp" will point at the signature word for the next
    122  * entry or for the EOCD.
    123  */
    124 status_t ZipEntry::CentralDirEntry::rewrite(FILE* fp)
    125 {
    126     uint8_t buf[kCDELen];
    127     uint16_t fileNameLength, extraFieldLength, fileCommentLength;
    128 
    129     if (fread(buf, 1, kCDELen, fp) != kCDELen)
    130         return -1;
    131 
    132     if (ZipEntry::getLongLE(&buf[0x00]) != kSignature) {
    133         LOG("Whoops: didn't find expected signature\n");
    134         return -1;
    135     }
    136 
    137     ZipEntry::putShortLE(&buf[0x0c], STATIC_TIME);
    138     ZipEntry::putShortLE(&buf[0x0e], STATIC_DATE);
    139 
    140     fileNameLength = ZipEntry::getShortLE(&buf[0x1c]);
    141     extraFieldLength = ZipEntry::getShortLE(&buf[0x1e]);
    142     fileCommentLength = ZipEntry::getShortLE(&buf[0x20]);
    143     mLocalHeaderRelOffset = ZipEntry::getLongLE(&buf[0x2a]);
    144 
    145     if (fseek(fp, -kCDELen, SEEK_CUR) != 0)
    146         return -1;
    147 
    148     if (fwrite(buf, 1, kCDELen, fp) != kCDELen)
    149         return -1;
    150 
    151     if (fseek(fp, fileNameLength + extraFieldLength + fileCommentLength, SEEK_CUR) != 0)
    152         return -1;
    153 
    154     return 0;
    155 }
    156