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      1 /*
      2  * Copyright (C) 2008 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  * Utility functions for dealing with optimized dex files.
     19  */
     20 
     21 #include "vm/DalvikVersion.h"
     22 
     23 #include <stdint.h>
     24 #include <stdlib.h>
     25 #include <unistd.h>
     26 #include <fcntl.h>
     27 #include <string.h>
     28 #include <sys/stat.h>
     29 #include <sys/file.h>
     30 #include <errno.h>
     31 
     32 #include "OptInvocation.h"
     33 #include "DexFile.h"
     34 
     35 static const char* kCacheDirectoryName = "dalvik-cache";
     36 static const char* kClassesDex = "classes.dex";
     37 
     38 /*
     39  * Given the filename of a .jar or .dex file, construct the DEX file cache
     40  * name.
     41  *
     42  * For a Jar, "subFileName" is the name of the entry (usually "classes.dex").
     43  * For a DEX, it may be NULL.
     44  *
     45  * Returns a newly-allocated string, or NULL on failure.
     46  */
     47 char* dexOptGenerateCacheFileName(const char* fileName, const char* subFileName)
     48 {
     49     char nameBuf[512];
     50     char absoluteFile[sizeof(nameBuf)];
     51     const size_t kBufLen = sizeof(nameBuf) - 1;
     52     const char* dataRoot;
     53     char* cp;
     54 
     55     /*
     56      * Get the absolute path of the Jar or DEX file.
     57      */
     58     absoluteFile[0] = '\0';
     59     if (fileName[0] != '/') {
     60         /*
     61          * Generate the absolute path.  This doesn't do everything it
     62          * should, e.g. if filename is "./out/whatever" it doesn't crunch
     63          * the leading "./" out, but it'll do.
     64          */
     65         if (getcwd(absoluteFile, kBufLen) == NULL) {
     66             ALOGE("Can't get CWD while opening jar file");
     67             return NULL;
     68         }
     69         strncat(absoluteFile, "/", kBufLen);
     70     }
     71     strncat(absoluteFile, fileName, kBufLen);
     72 
     73     /*
     74      * Append the name of the Jar file entry, if any.  This is not currently
     75      * required, but will be if we start putting more than one DEX file
     76      * in a Jar.
     77      */
     78     if (subFileName != NULL) {
     79         strncat(absoluteFile, "/", kBufLen);
     80         strncat(absoluteFile, subFileName, kBufLen);
     81     }
     82 
     83     /* Turn the path into a flat filename by replacing
     84      * any slashes after the first one with '@' characters.
     85      */
     86     cp = absoluteFile + 1;
     87     while (*cp != '\0') {
     88         if (*cp == '/') {
     89             *cp = '@';
     90         }
     91         cp++;
     92     }
     93 
     94     /* Build the name of the cache directory.
     95      */
     96     dataRoot = getenv("ANDROID_DATA");
     97     if (dataRoot == NULL)
     98         dataRoot = "/data";
     99     snprintf(nameBuf, kBufLen, "%s/%s", dataRoot, kCacheDirectoryName);
    100 
    101     /* Tack on the file name for the actual cache file path.
    102      */
    103     strncat(nameBuf, absoluteFile, kBufLen);
    104 
    105     ALOGV("Cache file for '%s' '%s' is '%s'", fileName, subFileName, nameBuf);
    106     return strdup(nameBuf);
    107 }
    108 
    109 /*
    110  * Create a skeletal "opt" header in a new file.  Most of the fields are
    111  * initialized to garbage, but we fill in "dexOffset" so others can
    112  * see how large the header is.
    113  *
    114  * "fd" must be positioned at the start of the file.  On return, it will
    115  * be positioned just past the header, and the place where the DEX data
    116  * should go.
    117  *
    118  * Returns 0 on success, errno on failure.
    119  */
    120 int dexOptCreateEmptyHeader(int fd)
    121 {
    122     DexOptHeader optHdr;
    123     ssize_t actual;
    124 
    125     assert(lseek(fd, 0, SEEK_CUR) == 0);
    126 
    127     /*
    128      * The data is only expected to be readable on the current system, so
    129      * we just write the structure.  We do need the file offset to be 64-bit
    130      * aligned to fulfill a DEX requirement.
    131      */
    132     assert((sizeof(optHdr) & 0x07) == 0);
    133     memset(&optHdr, 0xff, sizeof(optHdr));
    134     optHdr.dexOffset = sizeof(optHdr);
    135     actual = write(fd, &optHdr, sizeof(optHdr));
    136     if (actual != sizeof(optHdr)) {
    137         int err = errno ? errno : -1;
    138         ALOGE("opt header write failed: %s", strerror(errno));
    139         return errno;
    140     }
    141 
    142     return 0;
    143 }
    144