The Tor Browser: mobile/android/thirdparty/com/squareup/picasso/MarkableInputStream.java@fc2d59ddac77

     1 /*

     2  * Copyright (C) 2013 Square, Inc.

     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 package com.squareup.picasso;

    18 import java.io.BufferedInputStream;

    19 import java.io.IOException;

    20 import java.io.InputStream;

    22 /**

    23  * An input stream wrapper that supports unlimited independent cursors for

    24  * marking and resetting. Each cursor is a token, and it's the caller's

    25  * responsibility to keep track of these.

    26  */

    27 final class MarkableInputStream extends InputStream {

    28   private final InputStream in;

    30   private long offset;

    31   private long reset;

    32   private long limit;

    34   private long defaultMark = -1;

    36   public MarkableInputStream(InputStream in) {

    37     if (!in.markSupported()) {

    38       in = new BufferedInputStream(in);

    39     }

    40     this.in = in;

    41   }

    43   /** Marks this place in the stream so we can reset back to it later. */

    44   @Override public void mark(int readLimit) {

    45     defaultMark = savePosition(readLimit);

    46   }

    48   /**

    49    * Returns an opaque token representing the current position in the stream.

    50    * Call {@link #reset(long)} to return to this position in the stream later.

    51    * It is an error to call {@link #reset(long)} after consuming more than

    52    * {@code readLimit} bytes from this stream.

    53    */

    54   public long savePosition(int readLimit) {

    55     long offsetLimit = offset + readLimit;

    56     if (limit < offsetLimit) {

    57       setLimit(offsetLimit);

    58     }

    59     return offset;

    60   }

    62   /**

    63    * Makes sure that the underlying stream can backtrack the full range from

    64    * {@code reset} thru {@code limit}. Since we can't call {@code mark()}

    65    * without also adjusting the reset-to-position on the underlying stream this

    66    * method resets first and then marks the union of the two byte ranges. On

    67    * buffered streams this additional cursor motion shouldn't result in any

    68    * additional I/O.

    69    */

    70   private void setLimit(long limit) {

    71     try {

    72       if (reset < offset && offset <= this.limit) {

    73         in.reset();

    74         in.mark((int) (limit - reset));

    75         skip(reset, offset);

    76       } else {

    77         reset = offset;

    78         in.mark((int) (limit - offset));

    79       }

    80       this.limit = limit;

    81     } catch (IOException e) {

    82       throw new IllegalStateException("Unable to mark: " + e);

    83     }

    84   }

    86   /** Resets the stream to the most recent {@link #mark mark}. */

    87   @Override public void reset() throws IOException {

    88     reset(defaultMark);

    89   }

    91   /** Resets the stream to the position recorded by {@code token}. */

    92   public void reset(long token) throws IOException {

    93     if (offset > limit || token < reset) {

    94       throw new IOException("Cannot reset");

    95     }

    96     in.reset();

    97     skip(reset, token);

    98     offset = token;

    99   }

   101   /** Skips {@code target - current} bytes and returns. */

   102   private void skip(long current, long target) throws IOException {

   103     while (current < target) {

   104       long skipped = in.skip(target - current);

   105       if (skipped == 0) {

   106         if (read() == -1) {

   107           break; // EOF

   108         } else {

   109           skipped = 1;

   110         }

   111       }

   112       current += skipped;

   113     }

   114   }

   116   @Override public int read() throws IOException {

   117     int result = in.read();

   118     if (result != -1) {

   119       offset++;

   120     }

   121     return result;

   122   }

   124   @Override public int read(byte[] buffer) throws IOException {

   125     int count = in.read(buffer);

   126     if (count != -1) {

   127       offset += count;

   128     }

   129     return count;

   130   }

   132   @Override public int read(byte[] buffer, int offset, int length) throws IOException {

   133     int count = in.read(buffer, offset, length);

   134     if (count != -1) {

   135       this.offset += count;

   136     }

   137     return count;

   138   }

   140   @Override public long skip(long byteCount) throws IOException {

   141     long skipped = in.skip(byteCount);

   142     offset += skipped;

   143     return skipped;

   144   }

   146   @Override public int available() throws IOException {

   147     return in.available();

   148   }

   150   @Override public void close() throws IOException {

   151     in.close();

   152   }

   154   @Override public boolean markSupported() {

   155     return in.markSupported();

   156   }

   157 }

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