1 files changed, 62 insertions, 0 deletions
diff --git a/src/libs/7zip/win/CPP/7zip/Archive/Common/FindSignature.cpp b/src/libs/7zip/win/CPP/7zip/Archive/Common/FindSignature.cpp
new file mode 100644
index 000000000..15aa6ceae
--- /dev/null
+++ b/src/libs/7zip/win/CPP/7zip/Archive/Common/FindSignature.cpp
@@ -0,0 +1,62 @@
+// FindSignature.cpp
+
+#include "StdAfx.h"
+
+#include "Common/Buffer.h"
+
+#include "FindSignature.h"
+
+#include "../../Common/StreamUtils.h"
+
+HRESULT FindSignatureInStream(ISequentialInStream *stream,
+    const Byte *signature, unsigned signatureSize,
+    const UInt64 *limit, UInt64 &resPos)
+{
+  resPos = 0;
+  CByteBuffer byteBuffer2;
+  byteBuffer2.SetCapacity(signatureSize);
+  RINOK(ReadStream_FALSE(stream, byteBuffer2, signatureSize));
+
+  if (memcmp(byteBuffer2, signature, signatureSize) == 0)
+    return S_OK;
+
+  const UInt32 kBufferSize = (1 << 16);
+  CByteBuffer byteBuffer;
+  byteBuffer.SetCapacity(kBufferSize);
+  Byte *buffer = byteBuffer;
+  UInt32 numPrevBytes = signatureSize - 1;
+  memcpy(buffer, (const Byte *)byteBuffer2 + 1, numPrevBytes);
+  resPos = 1;
+  for (;;)
+  {
+    if (limit != NULL)
+      if (resPos > *limit)
+        return S_FALSE;
+    do
+    {
+      UInt32 numReadBytes = kBufferSize - numPrevBytes;
+      UInt32 processedSize;
+      RINOK(stream->Read(buffer + numPrevBytes, numReadBytes, &processedSize));
+      numPrevBytes += processedSize;
+      if (processedSize == 0)
+        return S_FALSE;
+    }
+    while (numPrevBytes < signatureSize);
+    UInt32 numTests = numPrevBytes - signatureSize + 1;
+    for (UInt32 pos = 0; pos < numTests; pos++)
+    {
+      Byte b = signature[0];
+      for (; buffer[pos] != b && pos < numTests; pos++);
+      if (pos == numTests)
+        break;
+      if (memcmp(buffer + pos, signature, signatureSize) == 0)
+      {
+        resPos += pos;
+        return S_OK;
+      }
+    }
+    resPos += numTests;
+    numPrevBytes -= numTests;
+    memmove(buffer, buffer + numTests, numPrevBytes);
+  }
+}