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Sync with latest source-sdk-2013.

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This commit is contained in:
Nicholas Hastings
2014-10-30 12:30:57 -04:00
parent 6abc7fddca
commit aa5841f220
407 changed files with 6784 additions and 10498 deletions
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532
tier1/snappy.cpp
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@ -37,8 +37,17 @@
#include <vector>
#ifdef _WIN32
#pragma warning(disable:4018) // warning C4018: '<' : signed/unsigned mismatch
#pragma warning(disable:4389) // warning C4389: '==' : signed/unsigned mismatch
/* Define like size_t, omitting the "unsigned" */
#ifdef _WIN64
typedef __int64 ssize_t;
#else
typedef int ssize_t;
#endif
#endif //_WIN32
namespace snappy {
@ -86,6 +95,7 @@ enum {
COPY_2_BYTE_OFFSET = 2,
COPY_4_BYTE_OFFSET = 3
};
static const int kMaximumTagLength = 5; // COPY_4_BYTE_OFFSET plus the actual offset.
// Copy "len" bytes from "src" to "op", one byte at a time. Used for
// handling COPY operations where the input and output regions may
@ -98,8 +108,8 @@ enum {
// ababababababababababab
// Note that this does not match the semantics of either memcpy()
// or memmove().
static inline void IncrementalCopy(const char* src, char* op, int len) {
DCHECK_GT(len, 0);
static inline void IncrementalCopy(const char* src, char* op, ssize_t len) {
assert(len > 0);
do {
*op++ = *src++;
} while (--len > 0);
@ -140,22 +150,22 @@ namespace {
const int kMaxIncrementCopyOverflow = 10;
} // namespace
static inline void IncrementalCopyFastPath(const char* src, char* op, int len) {
inline void IncrementalCopyFastPath(const char* src, char* op, ssize_t len) {
while (op - src < 8) {
UNALIGNED_STORE64(op, UNALIGNED_LOAD64(src));
UnalignedCopy64(src, op);
len -= op - src;
op += op - src;
}
while (len > 0) {
UNALIGNED_STORE64(op, UNALIGNED_LOAD64(src));
UnalignedCopy64(src, op);
src += 8;
op += 8;
len -= 8;
}
}
} // namespace
static inline char* EmitLiteral(char* op,
const char* literal,
int len,
@ -176,8 +186,8 @@ static inline char* EmitLiteral(char* op,
// - The output will always have 32 spare bytes (see
// MaxCompressedLength).
if (allow_fast_path && len <= 16) {
UNALIGNED_STORE64(op, UNALIGNED_LOAD64(literal));
UNALIGNED_STORE64(op + 8, UNALIGNED_LOAD64(literal + 8));
UnalignedCopy64(literal, op);
UnalignedCopy64(literal + 8, op + 8);
return op + len;
}
} else {
@ -198,25 +208,25 @@ static inline char* EmitLiteral(char* op,
return op + len;
}
static inline char* EmitCopyLessThan64(char* op, int offset, int len) {
DCHECK_LE(len, 64);
DCHECK_GE(len, 4);
DCHECK_LT(offset, 65536);
static inline char* EmitCopyLessThan64(char* op, size_t offset, int len) {
assert(len <= 64);
assert(len >= 4);
assert(offset < 65536);
if ((len < 12) && (offset < 2048)) {
int len_minus_4 = len - 4;
size_t len_minus_4 = len - 4;
assert(len_minus_4 < 8); // Must fit in 3 bits
*op++ = COPY_1_BYTE_OFFSET | ((len_minus_4) << 2) | ((offset >> 8) << 5);
*op++ = (char)(COPY_1_BYTE_OFFSET + ((len_minus_4) << 2) + ((offset >> 8) << 5));
*op++ = offset & 0xff;
} else {
*op++ = COPY_2_BYTE_OFFSET | ((len-1) << 2);
LittleEndian::Store16(op, offset);
*op++ = COPY_2_BYTE_OFFSET + ((len-1) << 2);
LittleEndian::Store16(op, (snappy::uint16)offset);
op += 2;
}
return op;
}
static inline char* EmitCopy(char* op, int offset, int len) {
static inline char* EmitCopy(char* op, size_t offset, int len) {
// Emit 64 byte copies but make sure to keep at least four bytes reserved
while (len >= 68) {
op = EmitCopyLessThan64(op, offset, 64);
@ -253,12 +263,10 @@ uint16* WorkingMemory::GetHashTable(size_t input_size, int* table_size) {
// compression, and if the input is short, we won't need that
// many hash table entries anyway.
assert(kMaxHashTableSize >= 256);
int htsize = 256;
size_t htsize = 256;
while (htsize < kMaxHashTableSize && htsize < input_size) {
htsize <<= 1;
}
CHECK_EQ(0, htsize & (htsize - 1)) << ": must be power of two";
CHECK_LE(htsize, kMaxHashTableSize) << ": hash table too large";
uint16* table;
if (htsize <= ARRAYSIZE(small_table_)) {
@ -270,22 +278,55 @@ uint16* WorkingMemory::GetHashTable(size_t input_size, int* table_size) {
table = large_table_;
}
*table_size = htsize;
*table_size = (int)htsize;
memset(table, 0, htsize * sizeof(*table));
return table;
}
} // end namespace internal
// For 0 <= offset <= 4, GetUint32AtOffset(UNALIGNED_LOAD64(p), offset) will
// For 0 <= offset <= 4, GetUint32AtOffset(GetEightBytesAt(p), offset) will
// equal UNALIGNED_LOAD32(p + offset). Motivation: On x86-64 hardware we have
// empirically found that overlapping loads such as
// UNALIGNED_LOAD32(p) ... UNALIGNED_LOAD32(p+1) ... UNALIGNED_LOAD32(p+2)
// are slower than UNALIGNED_LOAD64(p) followed by shifts and casts to uint32.
//
// We have different versions for 64- and 32-bit; ideally we would avoid the
// two functions and just inline the UNALIGNED_LOAD64 call into
// GetUint32AtOffset, but GCC (at least not as of 4.6) is seemingly not clever
// enough to avoid loading the value multiple times then. For 64-bit, the load
// is done when GetEightBytesAt() is called, whereas for 32-bit, the load is
// done at GetUint32AtOffset() time.
#ifdef ARCH_K8
typedef uint64 EightBytesReference;
static inline EightBytesReference GetEightBytesAt(const char* ptr) {
return UNALIGNED_LOAD64(ptr);
}
static inline uint32 GetUint32AtOffset(uint64 v, int offset) {
DCHECK(0 <= offset && offset <= 4) << offset;
assert(offset >= 0);
assert(offset <= 4);
return v >> (LittleEndian::IsLittleEndian() ? 8 * offset : 32 - 8 * offset);
}
#else
typedef const char* EightBytesReference;
static inline EightBytesReference GetEightBytesAt(const char* ptr) {
return ptr;
}
static inline uint32 GetUint32AtOffset(const char* v, int offset) {
assert(offset >= 0);
assert(offset <= 4);
return UNALIGNED_LOAD32(v + offset);
}
#endif
// Flat array compression that does not emit the "uncompressed length"
// prefix. Compresses "input" string to the "*op" buffer.
//
@ -298,29 +339,29 @@ static inline uint32 GetUint32AtOffset(uint64 v, int offset) {
// Returns an "end" pointer into "op" buffer.
// "end - op" is the compressed size of "input".
namespace internal {
char* CompressFragment(const char* const input,
const size_t input_size,
char* CompressFragment(const char* input,
size_t input_size,
char* op,
uint16* table,
const int table_size) {
// "ip" is the input pointer, and "op" is the output pointer.
const char* ip = input;
CHECK_LE(input_size, kBlockSize);
CHECK_EQ(table_size & (table_size - 1), 0) << ": table must be power of two";
assert(input_size <= kBlockSize);
assert((table_size & (table_size - 1)) == 0); // table must be power of two
const int shift = 32 - Bits::Log2Floor(table_size);
DCHECK_EQ(kuint32max >> shift, table_size - 1);
assert(static_cast<int>(kuint32max >> shift) == table_size - 1);
const char* ip_end = input + input_size;
const char* base_ip = ip;
// Bytes in [next_emit, ip) will be emitted as literal bytes. Or
// [next_emit, ip_end) after the main loop.
const char* next_emit = ip;
const int kInputMarginBytes = 15;
const size_t kInputMarginBytes = 15;
if (PREDICT_TRUE(input_size >= kInputMarginBytes)) {
const char* ip_limit = input + input_size - kInputMarginBytes;
for (uint32 next_hash = Hash(++ip, shift); ; ) {
DCHECK_LT(next_emit, ip);
assert(next_emit < ip);
// The body of this loop calls EmitLiteral once and then EmitCopy one or
// more times. (The exception is that when we're close to exhausting
// the input we goto emit_remainder.)
@ -353,7 +394,7 @@ char* CompressFragment(const char* const input,
do {
ip = next_ip;
uint32 hash = next_hash;
DCHECK_EQ(hash, Hash(ip, shift));
assert(hash == Hash(ip, shift));
uint32 bytes_between_hash_lookups = skip++ >> 5;
next_ip = ip + bytes_between_hash_lookups;
if (PREDICT_FALSE(next_ip > ip_limit)) {
@ -361,8 +402,8 @@ char* CompressFragment(const char* const input,
}
next_hash = Hash(next_ip, shift);
candidate = base_ip + table[hash];
DCHECK_GE(candidate, base_ip);
DCHECK_LT(candidate, ip);
assert(candidate >= base_ip);
assert(candidate < ip);
table[hash] = ip - base_ip;
} while (PREDICT_TRUE(UNALIGNED_LOAD32(ip) !=
@ -371,7 +412,7 @@ char* CompressFragment(const char* const input,
// Step 2: A 4-byte match has been found. We'll later see if more
// than 4 bytes match. But, prior to the match, input
// bytes [next_emit, ip) are unmatched. Emit them as "literal bytes."
DCHECK_LE(next_emit + 16, ip_end);
assert(next_emit + 16 <= ip_end);
op = EmitLiteral(op, next_emit, ip - next_emit, true);
// Step 3: Call EmitCopy, and then see if another EmitCopy could
@ -382,7 +423,7 @@ char* CompressFragment(const char* const input,
// though we don't yet know how big the literal will be. We handle that
// by proceeding to the next iteration of the main loop. We also can exit
// this loop via goto if we get close to exhausting the input.
uint64 input_bytes = 0;
EightBytesReference input_bytes;
uint32 candidate_bytes = 0;
do {
@ -391,8 +432,8 @@ char* CompressFragment(const char* const input,
const char* base = ip;
int matched = 4 + FindMatchLength(candidate + 4, ip + 4, ip_end);
ip += matched;
int offset = base - candidate;
DCHECK_EQ(0, memcmp(base, candidate, matched));
size_t offset = base - candidate;
assert(0 == memcmp(base, candidate, matched));
op = EmitCopy(op, offset, matched);
// We could immediately start working at ip now, but to improve
// compression we first update table[Hash(ip - 1, ...)].
@ -401,7 +442,7 @@ char* CompressFragment(const char* const input,
if (PREDICT_FALSE(ip >= ip_limit)) {
goto emit_remainder;
}
input_bytes = UNALIGNED_LOAD64(insert_tail);
input_bytes = GetEightBytesAt(insert_tail);
uint32 prev_hash = HashBytes(GetUint32AtOffset(input_bytes, 0), shift);
table[prev_hash] = ip - base_ip - 1;
uint32 cur_hash = HashBytes(GetUint32AtOffset(input_bytes, 1), shift);
@ -439,12 +480,31 @@ char* CompressFragment(const char* const input,
// bool CheckLength() const;
//
// // Called repeatedly during decompression
// bool Append(const char* ip, uint32 length, bool allow_fast_path);
// bool AppendFromSelf(uint32 offset, uint32 length);
// };
// bool Append(const char* ip, size_t length);
// bool AppendFromSelf(uint32 offset, size_t length);
//
// "allow_fast_path" is a parameter that says if there is at least 16
// readable bytes in "ip". It is currently only used by SnappyArrayWriter.
// // The rules for how TryFastAppend differs from Append are somewhat
// // convoluted:
// //
// // - TryFastAppend is allowed to decline (return false) at any
// // time, for any reason -- just "return false" would be
// // a perfectly legal implementation of TryFastAppend.
// // The intention is for TryFastAppend to allow a fast path
// // in the common case of a small append.
// // - TryFastAppend is allowed to read up to <available> bytes
// // from the input buffer, whereas Append is allowed to read
// // <length>. However, if it returns true, it must leave
// // at least five (kMaximumTagLength) bytes in the input buffer
// // afterwards, so that there is always enough space to read the
// // next tag without checking for a refill.
// // - TryFastAppend must always return decline (return false)
// // if <length> is 61 or more, as in this case the literal length is not
// // decoded fully. In practice, this should not be a big problem,
// // as it is unlikely that one would implement a fast path accepting
// // this much data.
// //
// bool TryFastAppend(const char* ip, size_t available, size_t length);
// };
// -----------------------------------------------------------------------
// Lookup table for decompression code. Generated by ComputeTable() below.
@ -511,9 +571,9 @@ static uint16 MakeEntry(unsigned int extra,
unsigned int len,
unsigned int copy_offset) {
// Check that all of the fields fit within the allocated space
DCHECK_EQ(extra, extra & 0x7); // At most 3 bits
DCHECK_EQ(copy_offset, copy_offset & 0x7); // At most 3 bits
DCHECK_EQ(len, len & 0x7f); // At most 7 bits
assert(extra == (extra & 0x7)); // At most 3 bits
assert(copy_offset == (copy_offset & 0x7)); // At most 3 bits
assert(len == (len & 0x7f)); // At most 7 bits
return len | (copy_offset << 8) | (extra << 11);
}
@ -571,9 +631,15 @@ static void ComputeTable() {
}
// Check that each entry was initialized exactly once.
CHECK_EQ(assigned, 256);
if (assigned != 256) {
fprintf(stderr, "ComputeTable: assigned only %d of 256\n", assigned);
abort();
}
for (int i = 0; i < 256; i++) {
CHECK_NE(dst[i], 0xffff);
if (dst[i] == 0xffff) {
fprintf(stderr, "ComputeTable: did not assign byte %d\n", i);
abort();
}
}
if (FLAGS_snappy_dump_decompression_table) {
@ -588,10 +654,13 @@ static void ComputeTable() {
// Check that computed table matched recorded table
for (int i = 0; i < 256; i++) {
CHECK_EQ(dst[i], char_table[i]);
if (dst[i] != char_table[i]) {
fprintf(stderr, "ComputeTable: byte %d: computed (%x), expect (%x)\n",
i, static_cast<int>(dst[i]), static_cast<int>(char_table[i]));
abort();
}
}
}
REGISTER_MODULE_INITIALIZER(snappy, ComputeTable());
#endif /* !NDEBUG */
// Helper class for decompression
@ -602,7 +671,7 @@ class SnappyDecompressor {
const char* ip_limit_; // Points just past buffered bytes
uint32 peeked_; // Bytes peeked from reader (need to skip)
bool eof_; // Hit end of input without an error?
char scratch_[5]; // Temporary buffer for PeekFast() boundaries
char scratch_[kMaximumTagLength]; // See RefillTag().
// Ensure that all of the tag metadata for the next tag is available
// in [ip_..ip_limit_-1]. Also ensures that [ip,ip+4] is readable even
@ -634,7 +703,7 @@ class SnappyDecompressor {
// On succcess, stores the length in *result and returns true.
// On failure, returns false.
bool ReadUncompressedLength(uint32* result) {
DCHECK(ip_ == NULL); // Must not have read anything yet
assert(ip_ == NULL); // Must not have read anything yet
// Length is encoded in 1..5 bytes
*result = 0;
uint32 shift = 0;
@ -659,40 +728,63 @@ class SnappyDecompressor {
template <class Writer>
void DecompressAllTags(Writer* writer) {
const char* ip = ip_;
for ( ;; ) {
if (ip_limit_ - ip < 5) {
ip_ = ip;
if (!RefillTag()) return;
ip = ip_;
}
// We could have put this refill fragment only at the beginning of the loop.
// However, duplicating it at the end of each branch gives the compiler more
// scope to optimize the <ip_limit_ - ip> expression based on the local
// context, which overall increases speed.
#define MAYBE_REFILL() \
if (ip_limit_ - ip < kMaximumTagLength) { \
ip_ = ip; \
if (!RefillTag()) return; \
ip = ip_; \
}
MAYBE_REFILL();
for ( ;; ) {
const unsigned char c = *(reinterpret_cast<const unsigned char*>(ip++));
const uint32 entry = char_table[c];
const uint32 trailer = LittleEndian::Load32(ip) & wordmask[entry >> 11];
ip += entry >> 11;
const uint32 length = entry & 0xff;
if ((c & 0x3) == LITERAL) {
uint32 literal_length = length + trailer;
uint32 avail = ip_limit_ - ip;
size_t literal_length = (c >> 2) + 1u;
if (writer->TryFastAppend(ip, ip_limit_ - ip, literal_length)) {
assert(literal_length < 61);
ip += literal_length;
// NOTE(user): There is no MAYBE_REFILL() here, as TryFastAppend()
// will not return true unless there's already at least five spare
// bytes in addition to the literal.
continue;
}
if (PREDICT_FALSE(literal_length >= 61)) {
// Long literal.
const size_t literal_length_length = literal_length - 60;
literal_length =
(LittleEndian::Load32(ip) & wordmask[literal_length_length]) + 1;
ip += literal_length_length;
}
size_t avail = ip_limit_ - ip;
while (avail < literal_length) {
bool allow_fast_path = (avail >= 16);
if (!writer->Append(ip, avail, allow_fast_path)) return;
if (!writer->Append(ip, avail)) return;
literal_length -= avail;
reader_->Skip(peeked_);
size_t n;
ip = reader_->Peek(&n);
avail = (uint32)n;
peeked_ = avail;
avail = n;
peeked_ = (snappy::uint32)avail;
if (avail == 0) return; // Premature end of input
ip_limit_ = ip + avail;
}
bool allow_fast_path = (avail >= 16);
if (!writer->Append(ip, literal_length, allow_fast_path)) {
if (!writer->Append(ip, literal_length)) {
return;
}
ip += literal_length;
MAYBE_REFILL();
} else {
const uint32 entry = char_table[c];
const uint32 trailer = LittleEndian::Load32(ip) & wordmask[entry >> 11];
const uint32 length = entry & 0xff;
ip += entry >> 11;
// copy_offset/256 is encoded in bits 8..10. By just fetching
// those bits, we get copy_offset (since the bit-field starts at
// bit 8).
@ -700,8 +792,11 @@ class SnappyDecompressor {
if (!writer->AppendFromSelf(copy_offset + trailer, length)) {
return;
}
MAYBE_REFILL();
}
}
#undef MAYBE_REFILL
}
};
@ -712,7 +807,7 @@ bool SnappyDecompressor::RefillTag() {
reader_->Skip(peeked_); // All peeked bytes are used up
size_t n;
ip = reader_->Peek(&n);
peeked_ = (uint32)n;
peeked_ = (snappy::uint32)n;
if (n == 0) {
eof_ = true;
return false;
@ -721,11 +816,11 @@ bool SnappyDecompressor::RefillTag() {
}
// Read the tag character
DCHECK_LT(ip, ip_limit_);
assert(ip < ip_limit_);
const unsigned char c = *(reinterpret_cast<const unsigned char*>(ip));
const uint32 entry = char_table[c];
const uint32 needed = (entry >> 11) + 1; // +1 byte for 'c'
DCHECK_LE(needed, sizeof(scratch_));
assert(needed <= sizeof(scratch_));
// Read more bytes from reader if needed
uint32 nbuf = ip_limit_ - ip;
@ -741,15 +836,15 @@ bool SnappyDecompressor::RefillTag() {
size_t length;
const char* src = reader_->Peek(&length);
if (length == 0) return false;
uint32 to_add = min<uint32>(needed - nbuf, (uint32)length);
uint32 to_add = Min(needed - nbuf, (uint32)length);
memcpy(scratch_ + nbuf, src, to_add);
nbuf += to_add;
reader_->Skip(to_add);
}
DCHECK_EQ(nbuf, needed);
assert(nbuf == needed);
ip_ = scratch_;
ip_limit_ = scratch_ + needed;
} else if (nbuf < 5) {
} else if (nbuf < kMaximumTagLength) {
// Have enough bytes, but move into scratch_ so that we do not
// read past end of input
memmove(scratch_, ip, nbuf);
@ -765,23 +860,23 @@ bool SnappyDecompressor::RefillTag() {
}
template <typename Writer>
static bool InternalUncompress(Source* r,
Writer* writer,
uint32 max_len) {
static bool InternalUncompress(Source* r, Writer* writer) {
// Read the uncompressed length from the front of the compressed input
SnappyDecompressor decompressor(r);
uint32 uncompressed_len = 0;
if (!decompressor.ReadUncompressedLength(&uncompressed_len)) return false;
// Protect against possible DoS attack
if (static_cast<uint64>(uncompressed_len) > max_len) {
return false;
}
return InternalUncompressAllTags(&decompressor, writer, uncompressed_len);
}
template <typename Writer>
static bool InternalUncompressAllTags(SnappyDecompressor* decompressor,
Writer* writer,
uint32 uncompressed_len) {
writer->SetExpectedLength(uncompressed_len);
// Process the entire input
decompressor.DecompressAllTags(writer);
return (decompressor.eof() && writer->CheckLength());
decompressor->DecompressAllTags(writer);
return (decompressor->eof() && writer->CheckLength());
}
bool GetUncompressedLength(Source* source, uint32* result) {
@ -791,9 +886,9 @@ bool GetUncompressedLength(Source* source, uint32* result) {
size_t Compress(Source* reader, Sink* writer) {
size_t written = 0;
int N = (int)reader->Available();
size_t N = reader->Available();
char ulength[Varint::kMax32];
char* p = Varint::Encode32(ulength, N);
char* p = Varint::Encode32(ulength, (snappy::uint32)N);
writer->Append(ulength, p-ulength);
written += (p - ulength);
@ -805,11 +900,11 @@ size_t Compress(Source* reader, Sink* writer) {
// Get next block to compress (without copying if possible)
size_t fragment_size;
const char* fragment = reader->Peek(&fragment_size);
DCHECK_NE(fragment_size, 0) << ": premature end of input";
const int num_to_read = min(N, kBlockSize);
assert(fragment_size != 0); // premature end of input
const size_t num_to_read = min(N, kBlockSize);
size_t bytes_read = fragment_size;
int pending_advance = 0;
size_t pending_advance = 0;
if (bytes_read >= num_to_read) {
// Buffer returned by reader is large enough
pending_advance = num_to_read;
@ -827,23 +922,23 @@ size_t Compress(Source* reader, Sink* writer) {
while (bytes_read < num_to_read) {
fragment = reader->Peek(&fragment_size);
size_t n = min<size_t>(fragment_size, num_to_read - bytes_read);
size_t n = Min(fragment_size, num_to_read - bytes_read);
memcpy(scratch + bytes_read, fragment, n);
bytes_read += n;
reader->Skip(n);
}
DCHECK_EQ(bytes_read, num_to_read);
assert(bytes_read == num_to_read);
fragment = scratch;
fragment_size = num_to_read;
}
DCHECK_EQ(fragment_size, num_to_read);
assert(fragment_size == num_to_read);
// Get encoding table for compression
int table_size;
uint16* table = wmem.GetHashTable(num_to_read, &table_size);
// Compress input_fragment and append to dest
const size_t max_output = MaxCompressedLength(num_to_read);
const int max_output = (int)MaxCompressedLength(num_to_read);
// Need a scratch buffer for the output, in case the byte sink doesn't
// have room for us directly.
@ -870,6 +965,183 @@ size_t Compress(Source* reader, Sink* writer) {
return written;
}
// -----------------------------------------------------------------------
// IOVec interfaces
// -----------------------------------------------------------------------
// A type that writes to an iovec.
// Note that this is not a "ByteSink", but a type that matches the
// Writer template argument to SnappyDecompressor::DecompressAllTags().
class SnappyIOVecWriter {
private:
const struct iovec* output_iov_;
const size_t output_iov_count_;
// We are currently writing into output_iov_[curr_iov_index_].
int curr_iov_index_;
// Bytes written to output_iov_[curr_iov_index_] so far.
size_t curr_iov_written_;
// Total bytes decompressed into output_iov_ so far.
size_t total_written_;
// Maximum number of bytes that will be decompressed into output_iov_.
size_t output_limit_;
inline char* GetIOVecPointer(int index, size_t offset) {
return reinterpret_cast<char*>(output_iov_[index].iov_base) +
offset;
}
public:
// Does not take ownership of iov. iov must be valid during the
// entire lifetime of the SnappyIOVecWriter.
inline SnappyIOVecWriter(const struct iovec* iov, size_t iov_count)
: output_iov_(iov),
output_iov_count_(iov_count),
curr_iov_index_(0),
curr_iov_written_(0),
total_written_(0),
output_limit_((size_t)-1) {
}
inline void SetExpectedLength(size_t len) {
output_limit_ = len;
}
inline bool CheckLength() const {
return total_written_ == output_limit_;
}
inline bool Append(const char* ip, size_t len) {
if (total_written_ + len > output_limit_) {
return false;
}
while (len > 0) {
assert(curr_iov_written_ <= output_iov_[curr_iov_index_].iov_len);
if (curr_iov_written_ >= output_iov_[curr_iov_index_].iov_len) {
// This iovec is full. Go to the next one.
if (curr_iov_index_ + 1 >= output_iov_count_) {
return false;
}
curr_iov_written_ = 0;
++curr_iov_index_;
}
const size_t to_write = Min(
len, output_iov_[curr_iov_index_].iov_len - curr_iov_written_);
memcpy(GetIOVecPointer(curr_iov_index_, curr_iov_written_),
ip,
to_write);
curr_iov_written_ += to_write;
total_written_ += to_write;
ip += to_write;
len -= to_write;
}
return true;
}
inline bool TryFastAppend(const char* ip, size_t available, size_t len) {
const size_t space_left = output_limit_ - total_written_;
if (len <= 16 && available >= 16 + kMaximumTagLength && space_left >= 16 &&
output_iov_[curr_iov_index_].iov_len - curr_iov_written_ >= 16) {
// Fast path, used for the majority (about 95%) of invocations.
char* ptr = GetIOVecPointer(curr_iov_index_, curr_iov_written_);
UnalignedCopy64(ip, ptr);
UnalignedCopy64(ip + 8, ptr + 8);
curr_iov_written_ += len;
total_written_ += len;
return true;
}
return false;
}
inline bool AppendFromSelf(size_t offset, size_t len) {
if (offset > total_written_ || offset == 0) {
return false;
}
const size_t space_left = output_limit_ - total_written_;
if (len > space_left) {
return false;
}
// Locate the iovec from which we need to start the copy.
int from_iov_index = curr_iov_index_;
size_t from_iov_offset = curr_iov_written_;
while (offset > 0) {
if (from_iov_offset >= offset) {
from_iov_offset -= offset;
break;
}
offset -= from_iov_offset;
--from_iov_index;
assert(from_iov_index >= 0);
from_iov_offset = output_iov_[from_iov_index].iov_len;
}
// Copy <len> bytes starting from the iovec pointed to by from_iov_index to
// the current iovec.
while (len > 0) {
assert(from_iov_index <= curr_iov_index_);
if (from_iov_index != curr_iov_index_) {
const size_t to_copy = Min(
output_iov_[from_iov_index].iov_len - from_iov_offset,
len);
Append(GetIOVecPointer(from_iov_index, from_iov_offset), to_copy);
len -= to_copy;
if (len > 0) {
++from_iov_index;
from_iov_offset = 0;
}
} else {
assert(curr_iov_written_ <= output_iov_[curr_iov_index_].iov_len);
size_t to_copy = Min(output_iov_[curr_iov_index_].iov_len -
curr_iov_written_,
len);
if (to_copy == 0) {
// This iovec is full. Go to the next one.
if (curr_iov_index_ + 1 >= output_iov_count_) {
return false;
}
++curr_iov_index_;
curr_iov_written_ = 0;
continue;
}
if (to_copy > len) {
to_copy = len;
}
IncrementalCopy(GetIOVecPointer(from_iov_index, from_iov_offset),
GetIOVecPointer(curr_iov_index_, curr_iov_written_),
to_copy);
curr_iov_written_ += to_copy;
from_iov_offset += to_copy;
total_written_ += to_copy;
len -= to_copy;
}
}
return true;
}
};
bool RawUncompressToIOVec(const char* compressed, size_t compressed_length,
const struct iovec* iov, size_t iov_cnt) {
ByteArraySource reader(compressed, compressed_length);
return RawUncompressToIOVec(&reader, iov, iov_cnt);
}
bool RawUncompressToIOVec(Source* compressed, const struct iovec* iov,
size_t iov_cnt) {
SnappyIOVecWriter output(iov, iov_cnt);
return InternalUncompress(compressed, &output);
}
// -----------------------------------------------------------------------
// Flat array interfaces
// -----------------------------------------------------------------------
@ -897,34 +1169,51 @@ class SnappyArrayWriter {
return op_ == op_limit_;
}
inline bool Append(const char* ip, uint32 len, bool allow_fast_path) {
inline bool Append(const char* ip, size_t len) {
char* op = op_;
const int space_left = op_limit_ - op;
if (allow_fast_path && len <= 16 && space_left >= 16) {
// Fast path, used for the majority (about 90%) of dynamic invocations.
UNALIGNED_STORE64(op, UNALIGNED_LOAD64(ip));
UNALIGNED_STORE64(op + 8, UNALIGNED_LOAD64(ip + 8));
} else {
if (space_left < len) {
return false;
}
memcpy(op, ip, len);
const size_t space_left = op_limit_ - op;
if (space_left < len) {
return false;
}
memcpy(op, ip, len);
op_ = op + len;
return true;
}
inline bool AppendFromSelf(uint32 offset, uint32 len) {
inline bool TryFastAppend(const char* ip, size_t available, size_t len) {
char* op = op_;
const int space_left = op_limit_ - op;
const size_t space_left = op_limit_ - op;
if (len <= 16 && available >= 16 + kMaximumTagLength && space_left >= 16) {
// Fast path, used for the majority (about 95%) of invocations.
UnalignedCopy64(ip, op);
UnalignedCopy64(ip + 8, op + 8);
op_ = op + len;
return true;
} else {
return false;
}
}
if (op - base_ <= offset - 1u) { // -1u catches offset==0
inline bool AppendFromSelf(size_t offset, size_t len) {
char* op = op_;
const size_t space_left = op_limit_ - op;
// Check if we try to append from before the start of the buffer.
// Normally this would just be a check for "produced < offset",
// but "produced <= offset - 1u" is equivalent for every case
// except the one where offset==0, where the right side will wrap around
// to a very big number. This is convenient, as offset==0 is another
// invalid case that we also want to catch, so that we do not go
// into an infinite loop.
assert(op >= base_);
size_t produced = op - base_;
if (produced <= offset - 1u) {
return false;
}
if (len <= 16 && offset >= 8 && space_left >= 16) {
// Fast path, used for the majority (70-80%) of dynamic invocations.
UNALIGNED_STORE64(op, UNALIGNED_LOAD64(op - offset));
UNALIGNED_STORE64(op + 8, UNALIGNED_LOAD64(op - offset + 8));
UnalignedCopy64(op - offset, op);
UnalignedCopy64(op - offset + 8, op + 8);
} else {
if (space_left >= len + kMaxIncrementCopyOverflow) {
IncrementalCopyFastPath(op - offset, op, len);
@ -948,7 +1237,7 @@ bool RawUncompress(const char* compressed, size_t n, char* uncompressed) {
bool RawUncompress(Source* compressed, char* uncompressed) {
SnappyArrayWriter output(uncompressed);
return InternalUncompress(compressed, &output, kuint32max);
return InternalUncompress(compressed, &output);
}
bool Uncompress(const char* compressed, size_t n, string* uncompressed) {
@ -956,9 +1245,9 @@ bool Uncompress(const char* compressed, size_t n, string* uncompressed) {
if (!GetUncompressedLength(compressed, n, &ulength)) {
return false;
}
// Protect against possible DoS attack
if ((static_cast<uint64>(ulength) + uncompressed->size()) >
uncompressed->max_size()) {
// On 32-bit builds: max_size() < kuint32max. Check for that instead
// of crashing (e.g., consider externally specified compressed data).
if (ulength > uncompressed->max_size()) {
return false;
}
STLStringResizeUninitialized(uncompressed, ulength);
@ -980,12 +1269,17 @@ class SnappyDecompressionValidator {
inline bool CheckLength() const {
return expected_ == produced_;
}
inline bool Append(const char* ip, uint32 len, bool allow_fast_path) {
inline bool Append(const char* ip, size_t len) {
produced_ += len;
return produced_ <= expected_;
}
inline bool AppendFromSelf(uint32 offset, uint32 len) {
if (produced_ <= offset - 1u) return false; // -1u catches offset==0
inline bool TryFastAppend(const char* ip, size_t available, size_t length) {
return false;
}
inline bool AppendFromSelf(size_t offset, size_t len) {
// See SnappyArrayWriter::AppendFromSelf for an explanation of
// the "offset - 1u" trick.
if (produced_ <= offset - 1u) return false;
produced_ += len;
return produced_ <= expected_;
}
@ -994,7 +1288,7 @@ class SnappyDecompressionValidator {
bool IsValidCompressedBuffer(const char* compressed, size_t n) {
ByteArraySource reader(compressed, n);
SnappyDecompressionValidator writer;
return InternalUncompress(&reader, &writer, kuint32max);
return InternalUncompress(&reader, &writer);
}
void RawCompress(const char* input,