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24 
25 #ifndef SHARE_CLASSFILE_CLASSFILESTREAM_HPP
26 #define SHARE_CLASSFILE_CLASSFILESTREAM_HPP
27 
28 #include "memory/allocation.hpp"
29 #include "utilities/bytes.hpp"
30 #include "utilities/exceptions.hpp"
31 
32 // Input stream for reading .class file
33 //
34 // The entire input stream is present in a buffer allocated by the caller.
35 // The caller is responsible for deallocating the buffer and for using
36 // ResourceMarks appropriately when constructing streams.
37 
38 class ClassPathEntry;
39 
40 class ClassFileStream: public ResourceObj {
41  private:
42   const u1* const _buffer_start; // Buffer bottom
43   const u1* const _buffer_end;   // Buffer top (one past last element)
44   mutable const u1* _current;    // Current buffer position
45   const char* const _source;     // Source of stream (directory name, ZIP/JAR archive name)
46   bool _need_verify;             // True if verification is on for the class file
47   bool _from_boot_loader_modules_image;  // True if this was created by ClassPathImageEntry.
48   void truncated_file_error(TRAPS) const ;
49 
50  protected:
51   const u1* clone_buffer() const;
52   const char* const clone_source() const;
53 
54  public:
55   static const bool verify;
56 
57   ClassFileStream(const u1* buffer,
58                   int length,
59                   const char* source,
60                   bool verify_stream = verify,  // to be verified by default
61                   bool from_boot_loader_modules_image = false);
62 
63   virtual const ClassFileStream* clone() const;
64 
65   // Buffer access
buffer() const66   const u1* buffer() const { return _buffer_start; }
length() const67   int length() const { return _buffer_end - _buffer_start; }
current() const68   const u1* current() const { return _current; }
set_current(const u1 * pos) const69   void set_current(const u1* pos) const {
70     assert(pos >= _buffer_start && pos <= _buffer_end, "invariant");
71     _current = pos;
72   }
73 
74   // for relative positioning
current_offset() const75   juint current_offset() const {
76     return (juint)(_current - _buffer_start);
77   }
source() const78   const char* source() const { return _source; }
need_verify() const79   bool need_verify() const { return _need_verify; }
set_verify(bool flag)80   void set_verify(bool flag) { _need_verify = flag; }
from_boot_loader_modules_image() const81   bool from_boot_loader_modules_image() const { return _from_boot_loader_modules_image; }
82 
check_truncated_file(bool b,TRAPS) const83   void check_truncated_file(bool b, TRAPS) const {
84     if (b) {
85       truncated_file_error(THREAD);
86     }
87   }
88 
guarantee_more(int size,TRAPS) const89   void guarantee_more(int size, TRAPS) const {
90     size_t remaining = (size_t)(_buffer_end - _current);
91     unsigned int usize = (unsigned int)size;
92     check_truncated_file(usize > remaining, CHECK);
93   }
94 
95   // Read u1 from stream
get_u1_fast() const96   u1 get_u1_fast() const {
97     return *_current++;
98   }
get_u1(TRAPS) const99   u1 get_u1(TRAPS) const {
100     if (_need_verify) {
101       guarantee_more(1, CHECK_0);
102     } else {
103       assert(1 <= _buffer_end - _current, "buffer overflow");
104     }
105     return get_u1_fast();
106   }
107 
108   // Read u2 from stream
get_u2_fast() const109   u2 get_u2_fast() const {
110     u2 res = Bytes::get_Java_u2((address)_current);
111     _current += 2;
112     return res;
113   }
get_u2(TRAPS) const114   u2 get_u2(TRAPS) const {
115     if (_need_verify) {
116       guarantee_more(2, CHECK_0);
117     } else {
118       assert(2 <= _buffer_end - _current, "buffer overflow");
119     }
120     return get_u2_fast();
121   }
122 
123   // Read u4 from stream
get_u4_fast() const124   u4 get_u4_fast() const {
125     u4 res = Bytes::get_Java_u4((address)_current);
126     _current += 4;
127     return res;
128   }
129 
130   // Read u8 from stream
get_u8_fast() const131   u8 get_u8_fast() const {
132     u8 res = Bytes::get_Java_u8((address)_current);
133     _current += 8;
134     return res;
135   }
136 
137   // Skip length elements from stream
skip_u1(int length,TRAPS) const138   void skip_u1(int length, TRAPS) const {
139     if (_need_verify) {
140       guarantee_more(length, CHECK);
141     }
142     skip_u1_fast(length);
143   }
skip_u1_fast(int length) const144   void skip_u1_fast(int length) const {
145     _current += length;
146   }
147 
skip_u2_fast(int length) const148   void skip_u2_fast(int length) const {
149     _current += 2 * length;
150   }
151 
skip_u4_fast(int length) const152   void skip_u4_fast(int length) const {
153     _current += 4 * length;
154   }
155 
156   // Tells whether eos is reached
at_eos() const157   bool at_eos() const { return _current == _buffer_end; }
158 
159   uint64_t compute_fingerprint() const;
160 };
161 
162 #endif // SHARE_CLASSFILE_CLASSFILESTREAM_HPP
163