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      1 /*
      2  *  Licensed to the Apache Software Foundation (ASF) under one or more
      3  *  contributor license agreements.  See the NOTICE file distributed with
      4  *  this work for additional information regarding copyright ownership.
      5  *  The ASF licenses this file to You under the Apache License, Version 2.0
      6  *  (the "License"); you may not use this file except in compliance with
      7  *  the License.  You may obtain a copy of the License at
      8  *
      9  *     http://www.apache.org/licenses/LICENSE-2.0
     10  *
     11  *  Unless required by applicable law or agreed to in writing, software
     12  *  distributed under the License is distributed on an "AS IS" BASIS,
     13  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     14  *  See the License for the specific language governing permissions and
     15  *  limitations under the License.
     16  */
     17 
     18 #define LOG_TAG "File"
     19 
     20 #include "JNIHelp.h"
     21 #include "JniConstants.h"
     22 #include "JniException.h"
     23 #include "ScopedPrimitiveArray.h"
     24 #include "ScopedUtfChars.h"
     25 #include "readlink.h"
     26 #include "toStringArray.h"
     27 
     28 #include <string>
     29 #include <vector>
     30 
     31 #include <dirent.h>
     32 #include <errno.h>
     33 #include <fcntl.h>
     34 #include <stdlib.h>
     35 #include <string.h>
     36 #include <sys/stat.h>
     37 #include <sys/types.h>
     38 #include <sys/vfs.h>
     39 #include <time.h>
     40 #include <unistd.h>
     41 #include <utime.h>
     42 
     43 static jstring File_readlink(JNIEnv* env, jclass, jstring javaPath) {
     44     ScopedUtfChars path(env, javaPath);
     45     if (path.c_str() == NULL) {
     46         return NULL;
     47     }
     48 
     49     std::string result;
     50     if (!readlink(path.c_str(), result)) {
     51         jniThrowIOException(env, errno);
     52         return NULL;
     53     }
     54     return env->NewStringUTF(result.c_str());
     55 }
     56 
     57 static jstring File_realpath(JNIEnv* env, jclass, jstring javaPath) {
     58     ScopedUtfChars path(env, javaPath);
     59     if (path.c_str() == NULL) {
     60         return NULL;
     61     }
     62 
     63     extern bool realpath(const char* path, std::string& resolved);
     64     std::string result;
     65     if (!realpath(path.c_str(), result)) {
     66         jniThrowIOException(env, errno);
     67         return NULL;
     68     }
     69     return env->NewStringUTF(result.c_str());
     70 }
     71 
     72 static jboolean File_setLastModifiedImpl(JNIEnv* env, jclass, jstring javaPath, jlong ms) {
     73     ScopedUtfChars path(env, javaPath);
     74     if (path.c_str() == NULL) {
     75         return JNI_FALSE;
     76     }
     77 
     78     // We want to preserve the access time.
     79     struct stat sb;
     80     if (stat(path.c_str(), &sb) == -1) {
     81         return JNI_FALSE;
     82     }
     83 
     84     // TODO: we could get microsecond resolution with utimes(3), "legacy" though it is.
     85     utimbuf times;
     86     times.actime = sb.st_atime;
     87     times.modtime = static_cast<time_t>(ms / 1000);
     88     return (utime(path.c_str(), &times) == 0);
     89 }
     90 
     91 // Iterates over the filenames in the given directory.
     92 class ScopedReaddir {
     93 public:
     94     ScopedReaddir(const char* path) {
     95         mDirStream = opendir(path);
     96         mIsBad = (mDirStream == NULL);
     97     }
     98 
     99     ~ScopedReaddir() {
    100         if (mDirStream != NULL) {
    101             closedir(mDirStream);
    102         }
    103     }
    104 
    105     // Returns the next filename, or NULL.
    106     const char* next() {
    107         if (mIsBad) {
    108             return NULL;
    109         }
    110         dirent* result = NULL;
    111         int rc = readdir_r(mDirStream, &mEntry, &result);
    112         if (rc != 0) {
    113             mIsBad = true;
    114             return NULL;
    115         }
    116         return (result != NULL) ? result->d_name : NULL;
    117     }
    118 
    119     // Has an error occurred on this stream?
    120     bool isBad() const {
    121         return mIsBad;
    122     }
    123 
    124 private:
    125     DIR* mDirStream;
    126     dirent mEntry;
    127     bool mIsBad;
    128 
    129     // Disallow copy and assignment.
    130     ScopedReaddir(const ScopedReaddir&);
    131     void operator=(const ScopedReaddir&);
    132 };
    133 
    134 typedef std::vector<std::string> DirEntries;
    135 
    136 // Reads the directory referred to by 'pathBytes', adding each directory entry
    137 // to 'entries'.
    138 static bool readDirectory(JNIEnv* env, jstring javaPath, DirEntries& entries) {
    139     ScopedUtfChars path(env, javaPath);
    140     if (path.c_str() == NULL) {
    141         return false;
    142     }
    143 
    144     ScopedReaddir dir(path.c_str());
    145     const char* filename;
    146     while ((filename = dir.next()) != NULL) {
    147         if (strcmp(filename, ".") != 0 && strcmp(filename, "..") != 0) {
    148             // TODO: this hides allocation failures from us. Push directory iteration up into Java?
    149             entries.push_back(filename);
    150         }
    151     }
    152     return !dir.isBad();
    153 }
    154 
    155 static jobjectArray File_listImpl(JNIEnv* env, jclass, jstring javaPath) {
    156     // Read the directory entries into an intermediate form.
    157     DirEntries entries;
    158     if (!readDirectory(env, javaPath, entries)) {
    159         return NULL;
    160     }
    161     // Translate the intermediate form into a Java String[].
    162     return toStringArray(env, entries);
    163 }
    164 
    165 static JNINativeMethod gMethods[] = {
    166     NATIVE_METHOD(File, listImpl, "(Ljava/lang/String;)[Ljava/lang/String;"),
    167     NATIVE_METHOD(File, readlink, "(Ljava/lang/String;)Ljava/lang/String;"),
    168     NATIVE_METHOD(File, realpath, "(Ljava/lang/String;)Ljava/lang/String;"),
    169     NATIVE_METHOD(File, setLastModifiedImpl, "(Ljava/lang/String;J)Z"),
    170 };
    171 void register_java_io_File(JNIEnv* env) {
    172     jniRegisterNativeMethods(env, "java/io/File", gMethods, NELEM(gMethods));
    173 }
    174