--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/classfile/imageFile.hpp Wed Dec 03 14:21:14 2014 +0000
@@ -0,0 +1,343 @@
+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_CLASSFILE_IMAGEFILE_HPP
+#define SHARE_VM_CLASSFILE_IMAGEFILE_HPP
+
+#include "classfile/classLoader.hpp"
+#include "memory/allocation.hpp"
+#include "memory/allocation.inline.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+// Image files are an alternate file format for storing classes and resources. The
+// goal is to supply file access which is faster and smaller that the jar format.
+// It should be noted that unlike jars information stored in an image is in native
+// endian format. This allows the image to be memory mapped into memory without
+// endian translation. This also means that images are platform dependent.
+//
+// Image files are structured as three sections;
+//
+// +-----------+
+// | Header |
+// +-----------+
+// | |
+// | Directory |
+// | |
+// +-----------+
+// | |
+// | |
+// | Resources |
+// | |
+// | |
+// +-----------+
+//
+// The header contains information related to identification and description of
+// contents.
+//
+// +-------------------------+
+// | Magic (0xCAFEDADA) |
+// +------------+------------+
+// | Major Vers | Minor Vers |
+// +------------+------------+
+// | Location Count |
+// +-------------------------+
+// | Attributes Size |
+// +-------------------------+
+// | Strings Size |
+// +-------------------------+
+//
+// Magic - means of identifying validity of the file. This avoids requiring a
+// special file extension.
+// Major vers, minor vers - differences in version numbers indicate structural
+// changes in the image.
+// Location count - number of locations/resources in the file. This count is also
+// the length of lookup tables used in the directory.
+// Attributes size - number of bytes in the region used to store location attribute
+// streams.
+// Strings size - the size of the region used to store strings used by the
+// directory and meta data.
+//
+// The directory contains information related to resource lookup. The algorithm
+// used for lookup is "A Practical Minimal Perfect Hashing Method"
+// (http://homepages.dcc.ufmg.br/~nivio/papers/wea05.pdf). Given a path string
+// in the form <package>/<base>.<extension> return the resource location
+// information;
+//
+// redirectIndex = hash(path, DEFAULT_SEED) % count;
+// redirect = redirectTable[redirectIndex];
+// if (redirect == 0) return not found;
+// locationIndex = redirect < 0 ? -1 - redirect : hash(path, redirect) % count;
+// location = locationTable[locationIndex];
+// if (!verify(location, path)) return not found;
+// return location;
+//
+// Note: The hash function takes an initial seed value. A different seed value
+// usually returns a different result for strings that would otherwise collide with
+// other seeds. The verify function guarantees the found resource location is
+// indeed the resource we are looking for.
+//
+// The following is the format of the directory;
+//
+// +-------------------+
+// | Redirect Table |
+// +-------------------+
+// | Attribute Offsets |
+// +-------------------+
+// | Attribute Data |
+// +-------------------+
+// | Strings |
+// +-------------------+
+//
+// Redirect Table - Array of 32-bit signed values representing actions that
+// should take place for hashed strings that map to that
+// value. Negative values indicate no hash collision and can be
+// quickly converted to indices into attribute offsets. Positive
+// values represent a new seed for hashing an index into attribute
+// offsets. Zero indicates not found.
+// Attribute Offsets - Array of 32-bit unsigned values representing offsets into
+// attribute data. Attribute offsets can be iterated to do a
+// full survey of resources in the image.
+// Attribute Data - Bytes representing compact attribute data for locations. (See
+// comments in ImageLocation.)
+// Strings - Collection of zero terminated UTF-8 strings used by the directory and
+// image meta data. Each string is accessed by offset. Each string is
+// unique. Offset zero is reserved for the empty string.
+//
+// Note that the memory mapped directory assumes 32 bit alignment of the image
+// header, the redirect table and the attribute offsets.
+//
+
+
+// Manage image file string table.
+class ImageStrings {
+private:
+ // Data bytes for strings.
+ u1* _data;
+ // Number of bytes in the string table.
+ u4 _size;
+
+public:
+ // Prime used to generate hash for Perfect Hashing.
+ static const u4 HASH_MULTIPLIER = 0x01000193;
+
+ ImageStrings(u1* data, u4 size) : _data(data), _size(size) {}
+
+ // Return the UTF-8 string beginning at offset.
+ inline const char* get(u4 offset) const {
+ assert(offset < _size, "offset exceeds string table size");
+ return (const char*)(_data + offset);
+ }
+
+ // Compute the Perfect Hashing hash code for the supplied string.
+ inline static u4 hash_code(const char* string) {
+ return hash_code(string, HASH_MULTIPLIER);
+ }
+
+ // Compute the Perfect Hashing hash code for the supplied string, starting at seed.
+ static u4 hash_code(const char* string, u4 seed);
+
+ // Test to see if string begins with start. If so returns remaining portion
+ // of string. Otherwise, NULL. Used to test sections of a path without
+ // copying.
+ static const char* starts_with(const char* string, const char* start);
+
+};
+
+// Manage image file location attribute streams. Within an image, a location's
+// attributes are compressed into a stream of bytes. An attribute stream is
+// composed of individual attribute sequences. Each attribute sequence begins with
+// a header byte containing the attribute 'kind' (upper 5 bits of header) and the
+// 'length' less 1 (lower 3 bits of header) of bytes that follow containing the
+// attribute value. Attribute values present as most significant byte first.
+//
+// Ex. Container offset (ATTRIBUTE_OFFSET) 0x33562 would be represented as 0x22
+// (kind = 4, length = 3), 0x03, 0x35, 0x62.
+//
+// An attribute stream is terminated with a header kind of ATTRIBUTE_END (header
+// byte of zero.)
+//
+// ImageLocation inflates the stream into individual values stored in the long
+// array _attributes. This allows an attribute value can be quickly accessed by
+// direct indexing. Unspecified values default to zero.
+//
+// Notes:
+// - Even though ATTRIBUTE_END is used to mark the end of the attribute stream,
+// streams will contain zero byte values to represent lesser significant bits.
+// Thus, detecting a zero byte is not sufficient to detect the end of an attribute
+// stream.
+// - ATTRIBUTE_OFFSET represents the number of bytes from the beginning of the region
+// storing the resources. Thus, in an image this represents the number of bytes
+// after the directory.
+// - Currently, compressed resources are represented by having a non-zero
+// ATTRIBUTE_COMPRESSED value. This represents the number of bytes stored in the
+// image, and the value of ATTRIBUTE_UNCOMPRESSED represents number of bytes of the
+// inflated resource in memory. If the ATTRIBUTE_COMPRESSED is zero then the value
+// of ATTRIBUTE_UNCOMPRESSED represents both the number of bytes in the image and
+// in memory. In the future, additional compression techniques will be used and
+// represented differently.
+// - Package strings include trailing slash and extensions include prefix period.
+//
+class ImageLocation {
+public:
+ // Attribute kind enumeration.
+ static const u1 ATTRIBUTE_END = 0; // End of attribute stream marker
+ static const u1 ATTRIBUTE_BASE = 1; // String table offset of resource path base
+ static const u1 ATTRIBUTE_PARENT = 2; // String table offset of resource path parent
+ static const u1 ATTRIBUTE_EXTENSION = 3; // String table offset of resource path extension
+ static const u1 ATTRIBUTE_OFFSET = 4; // Container byte offset of resource
+ static const u1 ATTRIBUTE_COMPRESSED = 5; // In image byte size of the compressed resource
+ static const u1 ATTRIBUTE_UNCOMPRESSED = 6; // In memory byte size of the uncompressed resource
+ static const u1 ATTRIBUTE_COUNT = 7; // Number of attribute kinds
+
+private:
+ // Values of inflated attributes.
+ u8 _attributes[ATTRIBUTE_COUNT];
+
+ // Return the attribute value number of bytes.
+ inline static u1 attribute_length(u1 data) {
+ return (data & 0x7) + 1;
+ }
+
+ // Return the attribute kind.
+ inline static u1 attribute_kind(u1 data) {
+ u1 kind = data >> 3;
+ assert(kind < ATTRIBUTE_COUNT, "invalid attribute kind");
+ return kind;
+ }
+
+ // Return the attribute length.
+ inline static u8 attribute_value(u1* data, u1 n) {
+ assert(0 < n && n <= 8, "invalid attribute value length");
+ u8 value = 0;
+
+ // Most significant bytes first.
+ for (u1 i = 0; i < n; i++) {
+ value <<= 8;
+ value |= data[i];
+ }
+
+ return value;
+ }
+
+public:
+ ImageLocation(u1* data);
+
+ // Retrieve an attribute value from the inflated array.
+ inline u8 get_attribute(u1 kind) const {
+ assert(ATTRIBUTE_END < kind && kind < ATTRIBUTE_COUNT, "invalid attribute kind");
+ return _attributes[kind];
+ }
+
+ // Retrieve an attribute string value from the inflated array.
+ inline const char* get_attribute(u4 kind, const ImageStrings& strings) const {
+ return strings.get((u4)get_attribute(kind));
+ }
+};
+
+// Manage the image file.
+class ImageFile: public CHeapObj<mtClass> {
+private:
+ // Image file marker.
+ static const u4 IMAGE_MAGIC = 0xCAFEDADA;
+ // Image file major version number.
+ static const u2 MAJOR_VERSION = 0;
+ // Image file minor version number.
+ static const u2 MINOR_VERSION = 1;
+
+ struct ImageHeader {
+ u4 _magic; // Image file marker
+ u2 _major_version; // Image file major version number
+ u2 _minor_version; // Image file minor version number
+ u4 _location_count; // Number of locations managed in index.
+ u4 _locations_size; // Number of bytes in attribute table.
+ u4 _strings_size; // Number of bytes in string table.
+ };
+
+ char* _name; // Name of image
+ int _fd; // File descriptor
+ bool _memory_mapped; // Is file memory mapped
+ ImageHeader _header; // Image header
+ u8 _index_size; // Total size of index
+ u1* _index_data; // Raw index data
+ s4* _redirect_table; // Perfect hash redirect table
+ u4* _offsets_table; // Location offset table
+ u1* _location_bytes; // Location attributes
+ u1* _string_bytes; // String table
+
+ // Compute number of bytes in image file index.
+ inline u8 index_size() {
+ return sizeof(ImageHeader) +
+ _header._location_count * sizeof(u4) * 2 +
+ _header._locations_size +
+ _header._strings_size;
+ }
+
+public:
+ ImageFile(const char* name);
+ ~ImageFile();
+
+ // Open image file for access.
+ bool open();
+ // Close image file.
+ void close();
+
+ // Retrieve name of image file.
+ inline const char* name() const {
+ return _name;
+ }
+
+ // Return a string table accessor.
+ inline const ImageStrings get_strings() const {
+ return ImageStrings(_string_bytes, _header._strings_size);
+ }
+
+ // Return number of locations in image file index.
+ inline u4 get_location_count() const {
+ return _header._location_count;
+ }
+
+ // Return location attribute stream for location i.
+ inline u1* get_location_data(u4 i) const {
+ u4 offset = _offsets_table[i];
+
+ return offset != 0 ? _location_bytes + offset : NULL;
+ }
+
+ // Return the attribute stream for a named resourced.
+ u1* find_location_data(const char* path) const;
+
+ // Verify that a found location matches the supplied path.
+ bool verify_location(ImageLocation& location, const char* path) const;
+
+ // Return the resource for the supplied location info.
+ u1* get_resource(ImageLocation& location) const;
+
+ // Return the resource associated with the path else NULL if not found.
+ void get_resource(const char* path, u1*& buffer, u8& size) const;
+
+ // Return an array of packages for a given module
+ GrowableArray<const char*>* packages(const char* name);
+};
+
+#endif // SHARE_VM_CLASSFILE_IMAGEFILE_HPP