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191 changes: 191 additions & 0 deletions
191
centrifuge/src/main/java/io/github/centrifugal/centrifuge/Fossil.java
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package io.github.centrifugal.centrifuge; | ||
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import java.io.ByteArrayOutputStream; | ||
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public class Fossil { | ||
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private static final int[] zValue = new int[] { | ||
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, | ||
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, | ||
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, | ||
8, 9, -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, | ||
20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, -1, -1, -1, | ||
-1, 36, -1, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, | ||
51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, -1, -1, -1, 63, -1, | ||
}; | ||
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// Reader class | ||
static class Reader { | ||
private byte[] a; | ||
private int pos; | ||
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public Reader(byte[] array) { | ||
this.a = array; | ||
this.pos = 0; | ||
} | ||
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public boolean haveBytes() { | ||
return this.pos < this.a.length; | ||
} | ||
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public int getByte() { | ||
if (this.pos >= this.a.length) { | ||
throw new IndexOutOfBoundsException("out of bounds"); | ||
} | ||
int b = this.a[this.pos++] & 0xFF; | ||
return b; | ||
} | ||
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public char getChar() { | ||
return (char) getByte(); | ||
} | ||
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public int getInt() { | ||
int v = 0; | ||
int c; | ||
while (haveBytes() && (c = zValue[getByte() & 0x7F]) >= 0) { | ||
v = (v << 6) + c; | ||
} | ||
this.pos--; | ||
return v; | ||
} | ||
} | ||
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// Writer class | ||
static class Writer { | ||
private ByteArrayOutputStream a = new ByteArrayOutputStream(); | ||
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public byte[] toByteArray() { | ||
return a.toByteArray(); | ||
} | ||
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// Copy from array 'arr' from 'start' to 'end' (exclusive) | ||
public void putArray(byte[] arr, int start, int end) { | ||
if (start < 0 || end > arr.length || start > end) { | ||
throw new IndexOutOfBoundsException("Invalid start or end index"); | ||
} | ||
a.write(arr, start, end - start); | ||
} | ||
} | ||
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// Checksum function | ||
public static long checksum(byte[] arr) { | ||
int sum0 = 0, sum1 = 0, sum2 = 0, sum3 = 0; | ||
int z = 0; | ||
int N = arr.length; | ||
while (N >= 16) { | ||
sum0 += (arr[z + 0] & 0xFF); | ||
sum1 += (arr[z + 1] & 0xFF); | ||
sum2 += (arr[z + 2] & 0xFF); | ||
sum3 += (arr[z + 3] & 0xFF); | ||
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sum0 += (arr[z + 4] & 0xFF); | ||
sum1 += (arr[z + 5] & 0xFF); | ||
sum2 += (arr[z + 6] & 0xFF); | ||
sum3 += (arr[z + 7] & 0xFF); | ||
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sum0 += (arr[z + 8] & 0xFF); | ||
sum1 += (arr[z + 9] & 0xFF); | ||
sum2 += (arr[z + 10] & 0xFF); | ||
sum3 += (arr[z + 11] & 0xFF); | ||
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sum0 += (arr[z + 12] & 0xFF); | ||
sum1 += (arr[z + 13] & 0xFF); | ||
sum2 += (arr[z + 14] & 0xFF); | ||
sum3 += (arr[z + 15] & 0xFF); | ||
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z += 16; | ||
N -= 16; | ||
} | ||
while (N >= 4) { | ||
sum0 += (arr[z + 0] & 0xFF); | ||
sum1 += (arr[z + 1] & 0xFF); | ||
sum2 += (arr[z + 2] & 0xFF); | ||
sum3 += (arr[z + 3] & 0xFF); | ||
z += 4; | ||
N -= 4; | ||
} | ||
sum3 += (sum2 << 8) + (sum1 << 16) + (sum0 << 24); | ||
switch (N) { | ||
case 3: | ||
sum3 += (arr[z + 2] & 0xFF) << 8; | ||
case 2: | ||
sum3 += (arr[z + 1] & 0xFF) << 16; | ||
case 1: | ||
sum3 += (arr[z + 0] & 0xFF) << 24; | ||
break; | ||
default: | ||
break; | ||
} | ||
return sum3 & 0xFFFFFFFFL; | ||
} | ||
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/** | ||
* Apply a delta byte array to a source byte array, returning the target byte array. | ||
*/ | ||
public static byte[] applyDelta(byte[] source, byte[] delta) throws Exception { | ||
int total = 0; | ||
Reader zDelta = new Reader(delta); | ||
int lenSrc = source.length; | ||
int lenDelta = delta.length; | ||
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int limit = zDelta.getInt(); | ||
char c = zDelta.getChar(); | ||
if (c != '\n') { | ||
throw new Exception("size integer not terminated by '\\n'"); | ||
} | ||
Writer zOut = new Writer(); | ||
while (zDelta.haveBytes()) { | ||
int cnt = zDelta.getInt(); | ||
int ofst; | ||
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c = zDelta.getChar(); | ||
switch (c) { | ||
case '@': | ||
ofst = zDelta.getInt(); | ||
if (zDelta.haveBytes() && zDelta.getChar() != ',') { | ||
throw new Exception("copy command not terminated by ','"); | ||
} | ||
total += cnt; | ||
if (total > limit) { | ||
throw new Exception("copy exceeds output file size"); | ||
} | ||
if (ofst + cnt > lenSrc) { | ||
throw new Exception("copy extends past end of input"); | ||
} | ||
zOut.putArray(source, ofst, ofst + cnt); | ||
break; | ||
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case ':': | ||
total += cnt; | ||
if (total > limit) { | ||
throw new Exception("insert command gives an output larger than predicted"); | ||
} | ||
if (cnt > lenDelta - zDelta.pos) { | ||
throw new Exception("insert count exceeds size of delta"); | ||
} | ||
zOut.putArray(zDelta.a, zDelta.pos, zDelta.pos + cnt); | ||
zDelta.pos += cnt; | ||
break; | ||
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case ';': | ||
byte[] out = zOut.toByteArray(); | ||
long checksumValue = checksum(out); | ||
if (cnt != (int) checksumValue) { | ||
throw new Exception("bad checksum"); | ||
} | ||
if (total != limit) { | ||
throw new Exception("generated size does not match predicted size"); | ||
} | ||
return out; | ||
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default: | ||
System.out.println(c); | ||
throw new Exception("unknown delta operator"); | ||
} | ||
} | ||
throw new Exception("unterminated delta"); | ||
} | ||
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} |
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Original file line number | Diff line number | Diff line change |
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@@ -23,7 +23,6 @@ void setInfo(ClientInfo info) { | |
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private ClientInfo info; | ||
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public long getOffset() { | ||
return offset; | ||
} | ||
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