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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 <time.h>
     39 #include <unistd.h>
     40 #include <utime.h>
     41 
     42 static jstring File_readlink(JNIEnv* env, jclass, jstring javaPath) {
     43     ScopedUtfChars path(env, javaPath);
     44     if (path.c_str() == NULL) {
     45         return NULL;
     46     }
     47 
     48     std::string result;
     49     if (!readlink(path.c_str(), result)) {
     50         jniThrowIOException(env, errno);
     51         return NULL;
     52     }
     53     return env->NewStringUTF(result.c_str());
     54 }
     55 
     56 static jstring File_realpath(JNIEnv* env, jclass, jstring javaPath) {
     57     ScopedUtfChars path(env, javaPath);
     58     if (path.c_str() == NULL) {
     59         return NULL;
     60     }
     61 
     62     extern bool realpath(const char* path, std::string& resolved);
     63     std::string result;
     64     if (!realpath(path.c_str(), result)) {
     65         jniThrowIOException(env, errno);
     66         return NULL;
     67     }
     68     return env->NewStringUTF(result.c_str());
     69 }
     70 
     71 static jboolean File_setLastModifiedImpl(JNIEnv* env, jclass, jstring javaPath, jlong ms) {
     72     ScopedUtfChars path(env, javaPath);
     73     if (path.c_str() == NULL) {
     74         return JNI_FALSE;
     75     }
     76 
     77     // We want to preserve the access time.
     78     struct stat sb;
     79     if (stat(path.c_str(), &sb) == -1) {
     80         return JNI_FALSE;
     81     }
     82 
     83     // TODO: we could get microsecond resolution with utimes(3), "legacy" though it is.
     84     utimbuf times;
     85     times.actime = sb.st_atime;
     86     times.modtime = static_cast<time_t>(ms / 1000);
     87     return (utime(path.c_str(), &times) == 0);
     88 }
     89 
     90 // Iterates over the filenames in the given directory.
     91 class ScopedReaddir {
     92 public:
     93     ScopedReaddir(const char* path) {
     94         mDirStream = opendir(path);
     95         mIsBad = (mDirStream == NULL);
     96     }
     97 
     98     ~ScopedReaddir() {
     99         if (mDirStream != NULL) {
    100             closedir(mDirStream);
    101         }
    102     }
    103 
    104     // Returns the next filename, or NULL.
    105     const char* next() {
    106         if (mIsBad) {
    107             return NULL;
    108         }
    109         errno = 0;
    110         dirent* result = readdir(mDirStream);
    111         if (result != NULL) {
    112             return result->d_name;
    113         }
    114         if (errno != 0) {
    115             mIsBad = true;
    116         }
    117         return NULL;
    118     }
    119 
    120     // Has an error occurred on this stream?
    121     bool isBad() const {
    122         return mIsBad;
    123     }
    124 
    125 private:
    126     DIR* mDirStream;
    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