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30 */
31
32#ifndef LIBJIMAGE_IMAGEFILE_HPP
33#define LIBJIMAGE_IMAGEFILE_HPP
34
35#include <assert.h>
36
37#include "endian.hpp"
38#include "inttypes.hpp"
39
40// Image files are an alternate file format for storing classes and resources. The
41// goal is to supply file access which is faster and smaller than the jar format.
42// It should be noted that unlike jars, information stored in an image is in native
43// endian format. This allows the image to be mapped into memory without endian
44// translation. This also means that images are platform dependent.
45//
46// Image files are structured as three sections;
47//
48// +-----------+
49// | Header |
50// +-----------+
51// | |
52// | Index |
53// | |
54// +-----------+
55// | |
56// | |
57// | Resources |
58// | |
59// | |
60// +-----------+
61//
62// The header contains information related to identification and description of
63// contents.
64//
65// +-------------------------+
66// | Magic (0xCAFEDADA) |
67// +------------+------------+
68// | Major Vers | Minor Vers |
69// +------------+------------+
70// | Flags |
71// +-------------------------+
72// | Resource Count |
73// +-------------------------+
74// | Table Length |
75// +-------------------------+
76// | Attributes Size |
77// +-------------------------+
78// | Strings Size |
79// +-------------------------+
80//
81// Magic - means of identifying validity of the file. This avoids requiring a
82// special file extension.
83// Major vers, minor vers - differences in version numbers indicate structural
84// changes in the image.
85// Flags - various image wide flags (future).
86// Resource count - number of resources in the file.
87// Table length - the length of lookup tables used in the index.
88// Attributes size - number of bytes in the region used to store location attribute
89// streams.
90// Strings size - the size of the region used to store strings used by the
91// index and meta data.
92//
93// The index contains information related to resource lookup. The algorithm
94// used for lookup is "A Practical Minimal Perfect Hashing Method"
95// (http://homepages.dcc.ufmg.br/~nivio/papers/wea05.pdf). Given a path string
96// in the form /<module>/<package>/<base>.<extension> return the resource location
97// information;
98//
99// redirectIndex = hash(path, DEFAULT_SEED) % table_length;
100// redirect = redirectTable[redirectIndex];
101// if (redirect == 0) return not found;
102// locationIndex = redirect < 0 ? -1 - redirect : hash(path, redirect) % table_length;
103// location = locationTable[locationIndex];
104// if (!verify(location, path)) return not found;
105// return location;
106//
107// Note: The hash function takes an initial seed value. A different seed value
108// usually returns a different result for strings that would otherwise collide with
109// other seeds. The verify function guarantees the found resource location is
110// indeed the resource we are looking for.
111//
112// The following is the format of the index;
113//
114// +-------------------+
115// | Redirect Table |
116// +-------------------+
117// | Attribute Offsets |
118// +-------------------+
119// | Attribute Data |
120// +-------------------+
121// | Strings |
122// +-------------------+
123//
124// Redirect Table - Array of 32-bit signed values representing actions that
125// should take place for hashed strings that map to that
126// value. Negative values indicate no hash collision and can be
127// quickly converted to indices into attribute offsets. Positive
128// values represent a new seed for hashing an index into attribute
129// offsets. Zero indicates not found.
130// Attribute Offsets - Array of 32-bit unsigned values representing offsets into
131// attribute data. Attribute offsets can be iterated to do a
132// full survey of resources in the image. Offset of zero
133// indicates no attributes.
134// Attribute Data - Bytes representing compact attribute data for locations. (See
135// comments in ImageLocation.)
136// Strings - Collection of zero terminated UTF-8 strings used by the index and
137// image meta data. Each string is accessed by offset. Each string is
138// unique. Offset zero is reserved for the empty string.
139//
140// Note that the memory mapped index assumes 32 bit alignment of each component
141// in the index.
142//
143// Endianness of an image.
144// An image booted by hotspot is always in native endian. However, it is possible
145// to read (by the JDK) in alternate endian format. Primarily, this is during
146// cross platform scenarios. Ex, where javac needs to read an embedded image
147// to access classes for crossing compilation.
148//
149
150class ImageFileReader; // forward declaration
151
152// Manage image file string table.
153class ImageStrings {
154private:
155 u1* _data; // Data bytes for strings.
156 u4 _size; // Number of bytes in the string table.
157public:
158 enum {
159 // Not found result from find routine.
160 NOT_FOUND = -1,
161 // Prime used to generate hash for Perfect Hashing.
162 HASH_MULTIPLIER = 0x01000193
163 };
164
165 ImageStrings(u1* data, u4 size) : _data(data), _size(size) {}
166
167 // Return the UTF-8 string beginning at offset.
168 inline const char* get(u4 offset) const {
169 assert(offset < _size && "offset exceeds string table size");
170 return (const char*)(_data + offset);
171 }
172
173 // Compute the Perfect Hashing hash code for the supplied UTF-8 string.
174 inline static u4 hash_code(const char* string) {
175 return hash_code(string, HASH_MULTIPLIER);
176 }
177
178 // Compute the Perfect Hashing hash code for the supplied string, starting at seed.
179 static s4 hash_code(const char* string, s4 seed);
180
181 // Match up a string in a perfect hash table. Result still needs validation
182 // for precise match.
183 static s4 find(Endian* endian, const char* name, s4* redirect, u4 length);
184
185 // Test to see if UTF-8 string begins with the start UTF-8 string. If so,
186 // return non-NULL address of remaining portion of string. Otherwise, return
187 // NULL. Used to test sections of a path without copying from image string
188 // table.
189 static const char* starts_with(const char* string, const char* start);
190
191 // Test to see if UTF-8 string begins with start char. If so, return non-NULL
192 // address of remaining portion of string. Otherwise, return NULL. Used
193 // to test a character of a path without copying.
194 inline static const char* starts_with(const char* string, const char ch) {
195 return *string == ch ? string + 1 : NULL;
196 }
197};
198
199// Manage image file location attribute data. Within an image, a location's
200// attributes are compressed into a stream of bytes. An attribute stream is
201// composed of individual attribute sequences. Each attribute sequence begins with
202// a header byte containing the attribute 'kind' (upper 5 bits of header) and the
203// 'length' less 1 (lower 3 bits of header) of bytes that follow containing the
204// attribute value. Attribute values present as most significant byte first.
205//
206// Ex. Container offset (ATTRIBUTE_OFFSET) 0x33562 would be represented as 0x22
207// (kind = 4, length = 3), 0x03, 0x35, 0x62.
208//
209// An attribute stream is terminated with a header kind of ATTRIBUTE_END (header
210// byte of zero.)
211//
212// ImageLocation inflates the stream into individual values stored in the long
213// array _attributes. This allows an attribute value can be quickly accessed by
214// direct indexing. Unspecified values default to zero.
215//
216// Notes:
217// - Even though ATTRIBUTE_END is used to mark the end of the attribute stream,
218// streams will contain zero byte values to represent lesser significant bits.
219// Thus, detecting a zero byte is not sufficient to detect the end of an attribute
220// stream.
221// - ATTRIBUTE_OFFSET represents the number of bytes from the beginning of the region
222// storing the resources. Thus, in an image this represents the number of bytes
223// after the index.
224// - Currently, compressed resources are represented by having a non-zero
225// ATTRIBUTE_COMPRESSED value. This represents the number of bytes stored in the
226// image, and the value of ATTRIBUTE_UNCOMPRESSED represents number of bytes of the
227// inflated resource in memory. If the ATTRIBUTE_COMPRESSED is zero then the value
228// of ATTRIBUTE_UNCOMPRESSED represents both the number of bytes in the image and
229// in memory. In the future, additional compression techniques will be used and
230// represented differently.
231// - Package strings include trailing slash and extensions include prefix period.
232//
233class ImageLocation {
234public:
235 enum {
236 ATTRIBUTE_END, // End of attribute stream marker
237 ATTRIBUTE_MODULE, // String table offset of module name
238 ATTRIBUTE_PARENT, // String table offset of resource path parent
239 ATTRIBUTE_BASE, // String table offset of resource path base
240 ATTRIBUTE_EXTENSION, // String table offset of resource path extension
241 ATTRIBUTE_OFFSET, // Container byte offset of resource
242 ATTRIBUTE_COMPRESSED, // In image byte size of the compressed resource
243 ATTRIBUTE_UNCOMPRESSED, // In memory byte size of the uncompressed resource
244 ATTRIBUTE_COUNT // Number of attribute kinds
245 };
246
247private:
248 // Values of inflated attributes.
249 u8 _attributes[ATTRIBUTE_COUNT];
250
251 // Return the attribute value number of bytes.
252 inline static u1 attribute_length(u1 data) {
253 return (data & 0x7) + 1;
254 }
255
256 // Return the attribute kind.
257 inline static u1 attribute_kind(u1 data) {
258 u1 kind = data >> 3;
259 assert(kind < ATTRIBUTE_COUNT && "invalid attribute kind");
260 return kind;
261 }
262
263 // Return the attribute length.
264 inline static u8 attribute_value(u1* data, u1 n) {
265 assert(0 < n && n <= 8 && "invalid attribute value length");
266 u8 value = 0;
267 // Most significant bytes first.
268 for (u1 i = 0; i < n; i++) {
269 value <<= 8;
270 value |= data[i];
271 }
272 return value;
273 }
274
275public:
276 ImageLocation() {
277 clear_data();
278 }
279
280 ImageLocation(u1* data) {
281 clear_data();
282 set_data(data);
283 }
284
285 // Inflates the attribute stream into individual values stored in the long
286 // array _attributes. This allows an attribute value to be quickly accessed by
287 // direct indexing. Unspecified values default to zero.
288 void set_data(u1* data);
289
290 // Zero all attribute values.
291 void clear_data();
292
293 // Retrieve an attribute value from the inflated array.
294 inline u8 get_attribute(u1 kind) const {
295 assert(ATTRIBUTE_END < kind && kind < ATTRIBUTE_COUNT && "invalid attribute kind");
296 return _attributes[kind];
297 }
298
299 // Retrieve an attribute string value from the inflated array.
300 inline const char* get_attribute(u4 kind, const ImageStrings& strings) const {
301 return strings.get((u4)get_attribute(kind));
302 }
303};
304
305//
306// Manage the image module meta data.
307class ImageModuleData {
308 const ImageFileReader* _image_file; // Source image file
309 Endian* _endian; // Endian handler
310
311public:
312 ImageModuleData(const ImageFileReader* image_file);
313 ~ImageModuleData();
314
315 // Return the module in which a package resides. Returns NULL if not found.
316 const char* package_to_module(const char* package_name);
317};
318
319// Image file header, starting at offset 0.
320class ImageHeader {
321private:
322 u4 _magic; // Image file marker
323 u4 _version; // Image file major version number
324 u4 _flags; // Image file flags
325 u4 _resource_count; // Number of resources in file
326 u4 _table_length; // Number of slots in index tables
327 u4 _locations_size; // Number of bytes in attribute table
328 u4 _strings_size; // Number of bytes in string table
329
330public:
331 u4 magic() const { return _magic; }
332 u4 magic(Endian* endian) const { return endian->get(_magic); }
333 void set_magic(Endian* endian, u4 magic) { return endian->set(_magic, magic); }
334
335 u4 major_version(Endian* endian) const { return endian->get(_version) >> 16; }
336 u4 minor_version(Endian* endian) const { return endian->get(_version) & 0xFFFF; }
337 void set_version(Endian* endian, u4 major_version, u4 minor_version) {
338 return endian->set(_version, major_version << 16 | minor_version);
339 }
340
341 u4 flags(Endian* endian) const { return endian->get(_flags); }
342 void set_flags(Endian* endian, u4 value) { return endian->set(_flags, value); }
343
344 u4 resource_count(Endian* endian) const { return endian->get(_resource_count); }
345 void set_resource_count(Endian* endian, u4 count) { return endian->set(_resource_count, count); }
346
347 u4 table_length(Endian* endian) const { return endian->get(_table_length); }
348 void set_table_length(Endian* endian, u4 count) { return endian->set(_table_length, count); }
349
350 u4 locations_size(Endian* endian) const { return endian->get(_locations_size); }
351 void set_locations_size(Endian* endian, u4 size) { return endian->set(_locations_size, size); }
352
353 u4 strings_size(Endian* endian) const { return endian->get(_strings_size); }
354 void set_strings_size(Endian* endian, u4 size) { return endian->set(_strings_size, size); }
355};
356
357// Max path length limit independent of platform. Windows max path is 1024,
358// other platforms use 4096. The JCK fails several tests when 1024 is used.
359#define IMAGE_MAX_PATH 4096
360
361class ImageFileReader;
362
363// Manage a table of open image files. This table allows multiple access points
364// to share an open image.
365class ImageFileReaderTable {
366private:
367 const static u4 _growth = 8; // Growth rate of the table
368 u4 _count; // Number of entries in the table
369 u4 _max; // Maximum number of entries allocated
370 ImageFileReader** _table; // Growable array of entries
371
372public:
373 ImageFileReaderTable();
374 ~ImageFileReaderTable();
375
376 // Return the number of entries.
377 inline u4 count() { return _count; }
378
379 // Return the ith entry from the table.
380 inline ImageFileReader* get(u4 i) { return _table[i]; }
381
382 // Add a new image entry to the table.
383 void add(ImageFileReader* image);
384
385 // Remove an image entry from the table.
386 void remove(ImageFileReader* image);
387
388 // Determine if image entry is in table.
389 bool contains(ImageFileReader* image);
390};
391
392// Manage the image file.
393// ImageFileReader manages the content of an image file.
394// Initially, the header of the image file is read for validation. If valid,
395// values in the header are used calculate the size of the image index. The
396// index is then memory mapped to allow load on demand and sharing. The
397// -XX:+MemoryMapImage flag determines if the entire file is loaded (server use.)
398// An image can be used by Hotspot and multiple reference points in the JDK, thus
399// it is desirable to share a reader. To accomodate sharing, a share table is
400// defined (see ImageFileReaderTable in imageFile.cpp) To track the number of
401// uses, ImageFileReader keeps a use count (_use). Use is incremented when
402// 'opened' by reference point and decremented when 'closed'. Use of zero
403// leads the ImageFileReader to be actually closed and discarded.
404class ImageFileReader {
405friend class ImageFileReaderTable;
406private:
407 // Manage a number of image files such that an image can be shared across
408 // multiple uses (ex. loader.)
409 static ImageFileReaderTable _reader_table;
410
411 // true if image should be fully memory mapped.
412 static bool memory_map_image;
413
414 char* _name; // Name of image
415 s4 _use; // Use count
416 int _fd; // File descriptor
417 Endian* _endian; // Endian handler
418 u8 _file_size; // File size in bytes
419 ImageHeader _header; // Image header
420 size_t _index_size; // Total size of index
421 u1* _index_data; // Raw index data
422 s4* _redirect_table; // Perfect hash redirect table
423 u4* _offsets_table; // Location offset table
424 u1* _location_bytes; // Location attributes
425 u1* _string_bytes; // String table
426 ImageModuleData *module_data; // The ImageModuleData for this image
427
428 ImageFileReader(const char* name, bool big_endian);
429 ~ImageFileReader();
430
431 // Compute number of bytes in image file index.
432 inline size_t index_size() {
433 return sizeof(ImageHeader) +
434 table_length() * sizeof(u4) * 2 + locations_size() + strings_size();
435 }
436
437public:
438 enum {
439 // Image file marker.
440 IMAGE_MAGIC = 0xCAFEDADA,
441 // Endian inverted Image file marker.
442 IMAGE_MAGIC_INVERT = 0xDADAFECA,
443 // Image file major version number.
444 MAJOR_VERSION = 1,
445 // Image file minor version number.
446 MINOR_VERSION = 0
447 };
448
449 // Locate an image if file already open.
450 static ImageFileReader* find_image(const char* name);
451
452 // Open an image file, reuse structure if file already open.
453 static ImageFileReader* open(const char* name, bool big_endian = Endian::is_big_endian());
454
455 // Close an image file if the file is not in use elsewhere.
456 static void close(ImageFileReader *reader);
457
458 // Return an id for the specifed ImageFileReader.
459 static u8 reader_to_ID(ImageFileReader *reader);
460
461 // Validate the image id.
462 static bool id_check(u8 id);
463
464 // Return an id for the specifed ImageFileReader.
465 static ImageFileReader* id_to_reader(u8 id);
466
467 // Open image file for read access.
468 bool open();
469
470 // Close image file.
471 void close();
472
473 // Read directly from the file.
474 bool read_at(u1* data, u8 size, u8 offset) const;
475
476 inline Endian* endian() const { return _endian; }
477
478 // Retrieve name of image file.
479 inline const char* name() const {
480 return _name;
481 }
482
483 // Retrieve size of image file.
484 inline u8 file_size() const {
485 return _file_size;
486 }
487
488 // Retrieve the size of the mapped image.
489 inline u8 map_size() const {
490 return (u8)(memory_map_image ? _file_size : _index_size);
491 }
492
493 // Return first address of index data.
494 inline u1* get_index_address() const {
495 return _index_data;
496 }
497
498 // Return first address of resource data.
499 inline u1* get_data_address() const {
500 return _index_data + _index_size;
501 }
502
503 // Get the size of the index data.
504 size_t get_index_size() const {
505 return _index_size;
506 }
507
508 inline u4 table_length() const {
509 return _header.table_length(_endian);
510 }
511
512 inline u4 locations_size() const {
513 return _header.locations_size(_endian);
514 }
515
516 inline u4 strings_size()const {
517 return _header.strings_size(_endian);
518 }
519
520 inline u4* offsets_table() const {
521 return _offsets_table;
522 }
523
524 // Increment use count.
525 inline void inc_use() {
526 _use++;
527 }
528
529 // Decrement use count.
530 inline bool dec_use() {
531 return --_use == 0;
532 }
533
534 // Return a string table accessor.
535 inline const ImageStrings get_strings() const {
536 return ImageStrings(_string_bytes, _header.strings_size(_endian));
537 }
538
539 // Return location attribute stream at offset.
540 inline u1* get_location_offset_data(u4 offset) const {
541 assert((u4)offset < _header.locations_size(_endian) &&
542 "offset exceeds location attributes size");
543 return offset != 0 ? _location_bytes + offset : NULL;
544 }
545
546 // Return location attribute stream for location i.
547 inline u1* get_location_data(u4 index) const {
548 return get_location_offset_data(get_location_offset(index));
549 }
550
551 // Return the location offset for index.
552 inline u4 get_location_offset(u4 index) const {
553 assert((u4)index < _header.table_length(_endian) &&
554 "index exceeds location count");
555 return _endian->get(_offsets_table[index]);
556 }
557
558 // Find the location attributes associated with the path. Returns true if
559 // the location is found, false otherwise.
560 bool find_location(const char* path, ImageLocation& location) const;
561
562 // Find the location index and size associated with the path.
563 // Returns the location index and size if the location is found,
564 // ImageFileReader::NOT_FOUND otherwise.
565 u4 find_location_index(const char* path, u8 *size) const;
566
567 // Verify that a found location matches the supplied path.
568 bool verify_location(ImageLocation& location, const char* path) const;
569
570 // Return the resource for the supplied location index.
571 void get_resource(u4 index, u1* uncompressed_data) const;
572
573 // Return the resource for the supplied path.
574 void get_resource(ImageLocation& location, u1* uncompressed_data) const;
575
576 // Return the ImageModuleData for this image
577 ImageModuleData * get_image_module_data();
578
579};
580#endif // LIBJIMAGE_IMAGEFILE_HPP
581