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hotspot/src/share/vm/classfile/classFileStream.hpp

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+/*
+ * Copyright 1997-2005 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+// Input stream for reading .class file
+//
+// The entire input stream is present in a buffer allocated by the caller.
+// The caller is responsible for deallocating the buffer and for using
+// ResourceMarks appropriately when constructing streams.
+
+class ClassFileStream: public ResourceObj {
+ private:
+  u1*   _buffer_start; // Buffer bottom
+  u1*   _buffer_end;   // Buffer top (one past last element)
+  u1*   _current;      // Current buffer position
+  char* _source;       // Source of stream (directory name, ZIP/JAR archive name)
+  bool  _need_verify;  // True if verification is on for the class file
+
+  void truncated_file_error(TRAPS);
+ public:
+  // Constructor
+  ClassFileStream(u1* buffer, int length, char* source);
+
+  // Buffer access
+  u1* buffer() const           { return _buffer_start; }
+  int length() const           { return _buffer_end - _buffer_start; }
+  u1* current() const          { return _current; }
+  void set_current(u1* pos)    { _current = pos; }
+  char* source() const         { return _source; }
+  void set_verify(bool flag)   { _need_verify = flag; }
+
+  void check_truncated_file(bool b, TRAPS) {
+    if (b) {
+      truncated_file_error(THREAD);
+    }
+  }
+
+  void guarantee_more(int size, TRAPS) {
+    size_t remaining = (size_t)(_buffer_end - _current);
+    unsigned int usize = (unsigned int)size;
+    check_truncated_file(usize > remaining, CHECK);
+  }
+
+  // Read u1 from stream
+  u1 get_u1(TRAPS);
+  u1 get_u1_fast() {
+    return *_current++;
+  }
+
+  // Read u2 from stream
+  u2 get_u2(TRAPS);
+  u2 get_u2_fast() {
+    u2 res = Bytes::get_Java_u2(_current);
+    _current += 2;
+    return res;
+  }
+
+  // Read u4 from stream
+  u4 get_u4(TRAPS);
+  u4 get_u4_fast() {
+    u4 res = Bytes::get_Java_u4(_current);
+    _current += 4;
+    return res;
+  }
+
+  // Read u8 from stream
+  u8 get_u8(TRAPS);
+  u8 get_u8_fast() {
+    u8 res = Bytes::get_Java_u8(_current);
+    _current += 8;
+    return res;
+  }
+
+  // Get direct pointer into stream at current position.
+  // Returns NULL if length elements are not remaining. The caller is
+  // responsible for calling skip below if buffer contents is used.
+  u1* get_u1_buffer() {
+    return _current;
+  }
+
+  u2* get_u2_buffer() {
+    return (u2*) _current;
+  }
+
+  // Skip length u1 or u2 elements from stream
+  void skip_u1(int length, TRAPS);
+  void skip_u1_fast(int length) {
+    _current += length;
+  }
+
+  void skip_u2(int length, TRAPS);
+  void skip_u2_fast(int length) {
+    _current += 2 * length;
+  }
+
+  // Tells whether eos is reached
+  bool at_eos() const          { return _current == _buffer_end; }
+};