forked from OSchip/llvm-project
Greg Clayton
parent
5dcda64338
commit
c396749670
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@ -0,0 +1,343 @@
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//
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// MappedHash.h
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//
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#ifndef liblldb_MappedHash_h_
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#define liblldb_MappedHash_h_
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#include <assert.h>
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#include <stdint.h>
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#include "lldb/Core/DataExtractor.h"
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#include "lldb/Core/Stream.h"
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class MappedHash
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{
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public:
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enum HashFunctionType
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{
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eHashFunctionDJB = 0u, // Daniel J Bernstein hash function that is also used by the ELF GNU_HASH sections
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};
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static uint32_t
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HashStringUsingDJB (const char *s)
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{
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uint32_t h = 5381;
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for (unsigned char c = *s; c; c = *++s)
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h = ((h << 5) + h) + c;
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return h;
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}
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static uint32_t
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HashString (const uint8_t hash_function, const char *s)
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{
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switch (hash_function)
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{
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case MappedHash::eHashFunctionDJB:
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return HashStringUsingDJB (s);
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default:
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break;
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}
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assert (!"Invalid hash function index");
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return 0;
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}
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static const uint32_t HASH_MAGIC = 0x48415348u;
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static const uint32_t HASH_CIGAM = 0x48534148u;
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template <typename T>
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struct Header
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{
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typedef T HeaderData;
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uint32_t magic; // 'HASH' magic value to allow endian detection
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uint16_t version; // Version number
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uint8_t addr_bytesize; // Size in bytes of an address
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uint8_t hash_function; // The hash function enumeration that was used
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uint32_t bucket_count; // The number of buckets in this hash table
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uint32_t hashes_count; // The total number of unique hash values and hash data offsets in this table
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uint32_t header_data_len; // The size in bytes of the "header_data" template member below
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HeaderData header_data; //
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Header () :
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magic ('HASH'),
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version (1),
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addr_bytesize (4),
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hash_function (eHashFunctionDJB),
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bucket_count (0),
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hashes_count (0),
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header_data_len (sizeof(T)),
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header_data ()
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{
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}
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virtual
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~Header()
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{
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}
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size_t
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GetByteSize() const
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{
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return sizeof(magic) +
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sizeof(version) +
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sizeof(addr_bytesize) +
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sizeof(hash_function) +
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sizeof(bucket_count) +
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sizeof(hashes_count) +
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sizeof(header_data_len) +
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header_data_len;
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}
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virtual size_t
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GetByteSize (const HeaderData &header_data) = 0;
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size_t
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SetHeaderDataByteSize (uint32_t header_data_byte_size)
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{
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header_data_len = header_data_byte_size;
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}
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void
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Dump (lldb_private::Stream &s)
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{
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s.Printf ("header.magic = 0x%8.8x\n", magic);
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s.Printf ("header.version = 0x%4.4x\n", version);
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s.Printf ("header.addr_bytesize = 0x%2.2x\n", addr_bytesize);
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s.Printf ("header.hash_function = 0x%2.2x\n", hash_function);
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s.Printf ("header.bucket_count = 0x%8.8x %u\n", bucket_count, bucket_count);
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s.Printf ("header.hashes_count = 0x%8.8x %u\n", hashes_count, hashes_count);
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s.Printf ("header.header_data_len = 0x%8.8x %u\n", header_data_len, header_data_len);
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}
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virtual uint32_t
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Read (lldb_private::DataExtractor &data, uint32_t offset)
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{
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if (data.ValidOffsetForDataOfSize (offset,
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sizeof(magic) +
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sizeof(version) +
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sizeof(addr_bytesize) +
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sizeof(hash_function) +
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sizeof(bucket_count) +
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sizeof(hashes_count) +
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sizeof(header_data_len)))
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{
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magic = data.GetU32 (&offset);
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if (magic != HASH_MAGIC)
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{
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if (magic == HASH_CIGAM)
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{
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switch (data.GetByteOrder())
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{
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case lldb::eByteOrderBig:
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data.SetByteOrder(lldb::eByteOrderLittle);
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break;
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case lldb::eByteOrderLittle:
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data.SetByteOrder(lldb::eByteOrderBig);
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break;
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default:
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return UINT32_MAX;
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}
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}
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else
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{
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// Magic bytes didn't match
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version = 0;
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return UINT32_MAX;
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}
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}
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version = data.GetU16 (&offset);
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if (version != 1)
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{
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// Unsupported version
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return UINT32_MAX;
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}
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addr_bytesize = data.GetU8 (&offset);
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hash_function = data.GetU8 (&offset);
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bucket_count = data.GetU32 (&offset);
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hashes_count = data.GetU32 (&offset);
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header_data_len = data.GetU32 (&offset);
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return offset;
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}
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return UINT32_MAX;
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}
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//
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// // Returns a buffer that contains a serialized version of this table
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// // that must be freed with free().
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// virtual void *
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// Write (int fd);
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};
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// A class for reading and using a saved hash table from a block of data
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// in memory
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template <typename __KeyType, class __HeaderType, class __HashData>
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class MemoryTable
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{
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public:
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typedef __HeaderType HeaderType;
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typedef __KeyType KeyType;
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typedef __HashData HashData;
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enum Result
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{
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eResultKeyMatch = 0u, // The entry was found, key matched and "pair" was filled in successfully
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eResultKeyMismatch = 1u, // Bucket hash data collision, but key didn't match
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eResultEndOfHashData = 2u, // The chain of items for this hash data in this bucket is terminated, search no more
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eResultError = 3u // Error parsing the hash data, abort
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};
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struct Pair
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{
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KeyType key;
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HashData value;
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};
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MemoryTable (lldb_private::DataExtractor &data) :
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m_header (),
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m_hash_indexes (NULL),
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m_hash_values (NULL),
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m_hash_offsets (NULL)
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{
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uint32_t offset = m_header.Read (data, 0);
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if (offset != UINT32_MAX)
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{
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m_hash_indexes = (uint32_t *)data.GetData (&offset, m_header.bucket_count * sizeof(uint32_t));
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m_hash_values = (uint32_t *)data.GetData (&offset, m_header.hashes_count * sizeof(uint32_t));
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m_hash_offsets = (uint32_t *)data.GetData (&offset, m_header.hashes_count * sizeof(uint32_t));
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}
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}
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virtual
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~MemoryTable ()
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{
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}
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bool
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IsValid () const
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{
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return m_header.version == 1 && m_header.hash_function == eHashFunctionDJB;
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}
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uint32_t
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GetHashIndex (uint32_t bucket_idx) const
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{
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if (m_hash_indexes && bucket_idx < m_header.bucket_count)
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return m_hash_indexes[bucket_idx];
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return UINT32_MAX;
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}
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uint32_t
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GetHashValue (uint32_t hash_idx) const
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{
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if (m_hash_values && hash_idx < m_header.hashes_count)
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return m_hash_values[hash_idx];
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return UINT32_MAX;
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}
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uint32_t
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GetHashDataOffset (uint32_t hash_idx) const
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{
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if (m_hash_offsets && hash_idx < m_header.hashes_count)
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return m_hash_offsets[hash_idx];
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return UINT32_MAX;
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}
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bool
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Find (const char *name, Pair &pair) const
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{
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if (IsValid ())
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{
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const uint32_t bucket_count = m_header.bucket_count;
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const uint32_t hash_count = m_header.hashes_count;
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const uint32_t hash_value = MappedHash::HashString (m_header.hash_function, name);
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const uint32_t bucket_idx = hash_value % bucket_count;
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uint32_t hash_idx = GetHashIndex (bucket_idx);
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if (hash_idx < hash_count)
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{
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for (; hash_idx < hash_count; ++hash_idx)
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{
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const uint32_t curr_hash_value = GetHashValue (hash_idx);
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if (curr_hash_value == hash_value)
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{
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uint32_t hash_data_offset = GetHashDataOffset (hash_idx);
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while (hash_data_offset != UINT32_MAX)
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{
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const uint32_t prev_hash_data_offset = hash_data_offset;
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Result hash_result = GetHashDataForName (name, &hash_data_offset, pair);
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// Check the result of getting our hash data
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switch (hash_result)
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{
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case eResultKeyMatch:
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return true;
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case eResultKeyMismatch:
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if (prev_hash_data_offset == hash_data_offset)
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return false;
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break;
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case eResultEndOfHashData:
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// The last HashData for this key has been reached, stop searching
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return false;
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case eResultError:
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// Error parsing the hash data, abort
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return false;
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}
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}
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}
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if ((curr_hash_value % bucket_count) != bucket_idx)
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break;
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}
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}
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}
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return false;
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}
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// This method must be implemented in any subclasses.
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// The KeyType is user specified and must somehow result in a string
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// value. For example, the KeyType might be a string offset in a string
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// table and subclasses can store their string table as a member of the
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// subclass and return a valie "const char *" given a "key". The value
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// could also be a C string pointer, in which case just returning "key"
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// will suffice.
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virtual const char *
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GetStringForKeyType (KeyType key) const = 0;
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// This method must be implemented in any subclasses and it must try to
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// read one "Pair" at the offset pointed to by the "hash_data_offset_ptr"
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// parameter. This offset should be updated as bytes are consumed and
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// a value "Result" enum should be returned. If the "name" matches the
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// full name for the "pair.key" (which must be filled in by this call),
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// then the HashData in the pair ("pair.value") should be extracted and
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// filled in and "eResultKeyMatch" should be returned. If "name" doesn't
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// match this string for the key, then "eResultKeyMismatch" should be
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// returned and all data for the current HashData must be consumed or
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// skipped and the "hash_data_offset_ptr" offset needs to be updated to
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// point to the next HashData. If the end of the HashData objects for
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// a given hash value have been reached, then "eResultEndOfHashData"
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// should be returned. If anything else goes wrong during parsing,
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// return "eResultError" and the corresponding "Find()" function will
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// be canceled and return false.
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virtual Result
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GetHashDataForName (const char *name,
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uint32_t* hash_data_offset_ptr,
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Pair &pair) const = 0;
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protected:
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// Implementation agnostic information
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HeaderType m_header;
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uint32_t *m_hash_indexes;
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uint32_t *m_hash_values;
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uint32_t *m_hash_offsets;
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};
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};
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#endif // #ifndef liblldb_MappedHash_h_
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