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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     status_t result = 0;
     90     uint8_t buf[kLFHLen];
     91 
     92     if (fread(buf, 1, kLFHLen, fp) != kLFHLen)
     93         return -1;
     94 
     95     if (ZipEntry::getLongLE(&buf[0x00]) != kSignature) {
     96         LOG("whoops: didn't find expected signature\n");
     97         return -1;
     98     }
     99 
    100     ZipEntry::putShortLE(&buf[0x0a], STATIC_TIME);
    101     ZipEntry::putShortLE(&buf[0x0c], STATIC_DATE);
    102 
    103     if (fseek(fp, -kLFHLen, SEEK_CUR) != 0)
    104         return -1;
    105 
    106     if (fwrite(buf, 1, kLFHLen, fp) != kLFHLen)
    107         return -1;
    108 
    109     return 0;
    110 }
    111 
    112 /*
    113  * ===========================================================================
    114  *      ZipEntry::CentralDirEntry
    115  * ===========================================================================
    116  */
    117 
    118 /*
    119  * Read and rewrite the central dir entry that appears next in the file.
    120  *
    121  * On entry, "fp" should be positioned on the signature bytes for the
    122  * entry.  On exit, "fp" will point at the signature word for the next
    123  * entry or for the EOCD.
    124  */
    125 status_t ZipEntry::CentralDirEntry::rewrite(FILE* fp)
    126 {
    127     status_t result = 0;
    128     uint8_t buf[kCDELen];
    129     uint16_t fileNameLength, extraFieldLength, fileCommentLength;
    130 
    131     if (fread(buf, 1, kCDELen, fp) != kCDELen)
    132         return -1;
    133 
    134     if (ZipEntry::getLongLE(&buf[0x00]) != kSignature) {
    135         LOG("Whoops: didn't find expected signature\n");
    136         return -1;
    137     }
    138 
    139     ZipEntry::putShortLE(&buf[0x0c], STATIC_TIME);
    140     ZipEntry::putShortLE(&buf[0x0e], STATIC_DATE);
    141 
    142     fileNameLength = ZipEntry::getShortLE(&buf[0x1c]);
    143     extraFieldLength = ZipEntry::getShortLE(&buf[0x1e]);
    144     fileCommentLength = ZipEntry::getShortLE(&buf[0x20]);
    145     mLocalHeaderRelOffset = ZipEntry::getLongLE(&buf[0x2a]);
    146 
    147     if (fseek(fp, -kCDELen, SEEK_CUR) != 0)
    148         return -1;
    149 
    150     if (fwrite(buf, 1, kCDELen, fp) != kCDELen)
    151         return -1;
    152 
    153     if (fseek(fp, fileNameLength + extraFieldLength + fileCommentLength, SEEK_CUR) != 0)
    154         return -1;
    155 
    156     return 0;
    157 }
    158