>From 6edae82d042631c5a0287081ae27e47b6bb34ee6 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Wed, 5 Jun 2013 15:29:47 +0200 Subject: [PATCH 1/2] Add snappy compression algorithm to /contrib Copied (with minimal modifications) from https://github.com/andikleen/snappy-c Code is licensed under a 3-clause BSD license and copyrighted by google. --- src/common/Makefile | 4 +- src/common/snappy-compat.h | 57 ++ src/common/snappy-int.h | 71 ++ src/common/snappy.c | 1536 ++++++++++++++++++++++++++++++++++++ src/include/common/snappy/snappy.h | 34 + 5 files changed, 1701 insertions(+), 1 deletion(-) create mode 100644 src/common/snappy-compat.h create mode 100644 src/common/snappy-int.h create mode 100644 src/common/snappy.c create mode 100644 src/include/common/snappy/snappy.h diff --git a/src/common/Makefile b/src/common/Makefile index cd97980..fe1979a 100644 --- a/src/common/Makefile +++ b/src/common/Makefile @@ -20,10 +20,12 @@ subdir = src/common top_builddir = ../.. include $(top_builddir)/src/Makefile.global +# XXX: override for snappy +override CPPFLAGS := -Wno-declaration-after-statement $(CPPFLAGS) override CPPFLAGS := -DFRONTEND $(CPPFLAGS) LIBS += $(PTHREAD_LIBS) -OBJS_COMMON = relpath.o +OBJS_COMMON = $(SUBDIROBJS) relpath.o snappy.o OBJS_FRONTEND = $(OBJS_COMMON) fe_memutils.o diff --git a/src/common/snappy-compat.h b/src/common/snappy-compat.h new file mode 100644 index 0000000..69d1735 --- /dev/null +++ b/src/common/snappy-compat.h @@ -0,0 +1,57 @@ +#ifdef __FreeBSD__ +# include +#elif defined(__APPLE_CC_) || defined(__MACH__) /* MacOS/X support */ +# include + +#if __DARWIN_BYTE_ORDER == __DARWIN_LITTLE_ENDIAN +# define htole16(x) (x) +# define le32toh(x) (x) +#elif __DARWIN_BYTE_ORDER == __DARWIN_BIG_ENDIAN +# define htole16(x) __DARWIN_OSSwapInt16(x) +# define le32toh(x) __DARWIN_OSSwapInt32(x) +#else +# error "Endianness is undefined" +#endif + + +#else +# include +#endif + +#include +#include +#include +#include +#include +#include + +typedef unsigned char u8; +typedef unsigned short u16; +typedef unsigned u32; +typedef unsigned long long u64; + +#define BUG_ON(x) assert(!(x)) + +#define get_unaligned(x) (*(x)) +#define get_unaligned_le32(x) (le32toh(*(u32 *)(x))) +#define put_unaligned(v,x) (*(x) = (v)) +#define put_unaligned_le16(v,x) (*(u16 *)(x) = htole16(v)) + +#define vmalloc(x) malloc(x) +#define vfree(x) free(x) + +#define EXPORT_SYMBOL(x) + +#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x))) + +#define likely(x) __builtin_expect((x), 1) +#define unlikely(x) __builtin_expect((x), 0) + +#define min_t(t,x,y) ((x) < (y) ? (x) : (y)) +#define max_t(t,x,y) ((x) > (y) ? (x) : (y)) + +#if __BYTE_ORDER == __LITTLE_ENDIAN +#define __LITTLE_ENDIAN__ 1 +#endif + +#define BITS_PER_LONG (__SIZEOF_LONG__ * 8) diff --git a/src/common/snappy-int.h b/src/common/snappy-int.h new file mode 100644 index 0000000..ad31b54 --- /dev/null +++ b/src/common/snappy-int.h @@ -0,0 +1,71 @@ +// Copyright 2011 Google Inc. All Rights Reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +// +// Various stubs for the open-source version of Snappy. + +#define likely(x) __builtin_expect(x, 1) +#define unlikely(x) __builtin_expect(x, 0) + +#define CRASH_UNLESS(x) assert(x) +#define CHECK(cond) assert(cond) +#define CHECK_LE(a, b) CRASH_UNLESS((a) <= (b)) +#define CHECK_GE(a, b) CRASH_UNLESS((a) >= (b)) +#define CHECK_EQ(a, b) CRASH_UNLESS((a) == (b)) +#define CHECK_NE(a, b) CRASH_UNLESS((a) != (b)) +#define CHECK_LT(a, b) CRASH_UNLESS((a) < (b)) +#define CHECK_GT(a, b) CRASH_UNLESS((a) > (b)) + +#define UNALIGNED_LOAD16(_p) (*(const uint16 *)(_p)) +#define UNALIGNED_LOAD32(_p) (*(const uint32 *)(_p)) +#define UNALIGNED_LOAD64(_p) (*(const uint64 *)(_p)) + +#define UNALIGNED_STORE16(_p, _val) (*(uint16 *)(_p) = (_val)) +#define UNALIGNED_STORE32(_p, _val) (*(uint32 *)(_p) = (_val)) +#define UNALIGNED_STORE64(_p, _val) (*(uint64 *)(_p) = (_val)) + +#ifdef NDEBUG + +#define DCHECK(cond) CRASH_UNLESS(true) +#define DCHECK_LE(a, b) CRASH_UNLESS(true) +#define DCHECK_GE(a, b) CRASH_UNLESS(true) +#define DCHECK_EQ(a, b) CRASH_UNLESS(true) +#define DCHECK_NE(a, b) CRASH_UNLESS(true) +#define DCHECK_LT(a, b) CRASH_UNLESS(true) +#define DCHECK_GT(a, b) CRASH_UNLESS(true) + +#else + +#define DCHECK(cond) CHECK(cond) +#define DCHECK_LE(a, b) CHECK_LE(a, b) +#define DCHECK_GE(a, b) CHECK_GE(a, b) +#define DCHECK_EQ(a, b) CHECK_EQ(a, b) +#define DCHECK_NE(a, b) CHECK_NE(a, b) +#define DCHECK_LT(a, b) CHECK_LT(a, b) +#define DCHECK_GT(a, b) CHECK_GT(a, b) + +#endif diff --git a/src/common/snappy.c b/src/common/snappy.c new file mode 100644 index 0000000..b61ed03 --- /dev/null +++ b/src/common/snappy.c @@ -0,0 +1,1536 @@ +/* + * C port of the snappy compressor from Google. + * This is a very fast compressor with comparable compression to lzo. + * Works best on 64bit little-endian, but should be good on others too. + * Ported by Andi Kleen. + * Based on snappy 1.0.3 plus some selected changes from SVN. + */ + +/* + * Copyright 2005 Google Inc. All Rights Reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following disclaimer + * in the documentation and/or other materials provided with the + * distribution. + * * Neither the name of Google Inc. nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "postgres.h" + +#include "common/snappy/snappy.h" +#include "snappy-compat.h" + +#include + +#define CRASH_UNLESS(x) BUG_ON(!(x)) +#define CHECK(cond) CRASH_UNLESS(cond) +#define CHECK_LE(a, b) CRASH_UNLESS((a) <= (b)) +#define CHECK_GE(a, b) CRASH_UNLESS((a) >= (b)) +#define CHECK_EQ(a, b) CRASH_UNLESS((a) == (b)) +#define CHECK_NE(a, b) CRASH_UNLESS((a) != (b)) +#define CHECK_LT(a, b) CRASH_UNLESS((a) < (b)) +#define CHECK_GT(a, b) CRASH_UNLESS((a) > (b)) + +#define UNALIGNED_LOAD16(_p) get_unaligned((u16 *)(_p)) +#define UNALIGNED_LOAD32(_p) get_unaligned((u32 *)(_p)) +#define UNALIGNED_LOAD64(_p) get_unaligned((u64 *)(_p)) + +#define UNALIGNED_STORE16(_p, _val) put_unaligned(_val, (u16 *)(_p)) +#define UNALIGNED_STORE32(_p, _val) put_unaligned(_val, (u32 *)(_p)) +#define UNALIGNED_STORE64(_p, _val) put_unaligned(_val, (u64 *)(_p)) + +#ifdef NDEBUG + +#define DCHECK(cond) do {} while(0) +#define DCHECK_LE(a, b) do {} while(0) +#define DCHECK_GE(a, b) do {} while(0) +#define DCHECK_EQ(a, b) do {} while(0) +#define DCHECK_NE(a, b) do {} while(0) +#define DCHECK_LT(a, b) do {} while(0) +#define DCHECK_GT(a, b) do {} while(0) + +#else + +#define DCHECK(cond) CHECK(cond) +#define DCHECK_LE(a, b) CHECK_LE(a, b) +#define DCHECK_GE(a, b) CHECK_GE(a, b) +#define DCHECK_EQ(a, b) CHECK_EQ(a, b) +#define DCHECK_NE(a, b) CHECK_NE(a, b) +#define DCHECK_LT(a, b) CHECK_LT(a, b) +#define DCHECK_GT(a, b) CHECK_GT(a, b) + +#endif + +static inline bool is_little_endian(void) +{ +#ifdef __LITTLE_ENDIAN__ + return true; +#endif + return false; +} + +static inline int log2_floor(u32 n) +{ + return n == 0 ? -1 : 31 ^ __builtin_clz(n); +} + +static inline int find_lsb_set_non_zero(u32 n) +{ + return __builtin_ctz(n); +} + +static inline int find_lsb_set_non_zero64(u64 n) +{ + return __builtin_ctzll(n); +} + +#define kmax32 5 + +/* + * Attempts to parse a varint32 from a prefix of the bytes in [ptr,limit-1]. + * Never reads a character at or beyond limit. If a valid/terminated varint32 + * was found in the range, stores it in *OUTPUT and returns a pointer just + * past the last byte of the varint32. Else returns NULL. On success, + * "result <= limit". + */ +static inline const char *varint_parse32_with_limit(const char *p, + const char *l, + u32 * OUTPUT) +{ + const unsigned char *ptr = (const unsigned char *)(p); + const unsigned char *limit = (const unsigned char *)(l); + u32 b, result; + + if (ptr >= limit) + return NULL; + b = *(ptr++); + result = b & 127; + if (b < 128) + goto done; + if (ptr >= limit) + return NULL; + b = *(ptr++); + result |= (b & 127) << 7; + if (b < 128) + goto done; + if (ptr >= limit) + return NULL; + b = *(ptr++); + result |= (b & 127) << 14; + if (b < 128) + goto done; + if (ptr >= limit) + return NULL; + b = *(ptr++); + result |= (b & 127) << 21; + if (b < 128) + goto done; + if (ptr >= limit) + return NULL; + b = *(ptr++); + result |= (b & 127) << 28; + if (b < 16) + goto done; + return NULL; /* Value is too long to be a varint32 */ +done: + *OUTPUT = result; + return (const char *)(ptr); +} + +/* + * REQUIRES "ptr" points to a buffer of length sufficient to hold "v". + * EFFECTS Encodes "v" into "ptr" and returns a pointer to the + * byte just past the last encoded byte. + */ +static inline char *varint_encode32(char *sptr, u32 v) +{ + /* Operate on characters as unsigneds */ + unsigned char *ptr = (unsigned char *)(sptr); + static const int B = 128; + + if (v < (1 << 7)) { + *(ptr++) = v; + } else if (v < (1 << 14)) { + *(ptr++) = v | B; + *(ptr++) = v >> 7; + } else if (v < (1 << 21)) { + *(ptr++) = v | B; + *(ptr++) = (v >> 7) | B; + *(ptr++) = v >> 14; + } else if (v < (1 << 28)) { + *(ptr++) = v | B; + *(ptr++) = (v >> 7) | B; + *(ptr++) = (v >> 14) | B; + *(ptr++) = v >> 21; + } else { + *(ptr++) = v | B; + *(ptr++) = (v >> 7) | B; + *(ptr++) = (v >> 14) | B; + *(ptr++) = (v >> 21) | B; + *(ptr++) = v >> 28; + } + return (char *)(ptr); +} + +#ifdef SG + +struct source { + struct iovec *iov; + int iovlen; + int curvec; + int curoff; + size_t total; +}; + +/* Only valid at beginning when nothing is consumed */ +static inline int available(struct source *s) +{ + return s->total; +} + +static inline const char *peek(struct source *s, size_t *len) +{ + if (likely(s->curvec < s->iovlen)) { + struct iovec *iv = &s->iov[s->curvec]; + if (s->curoff < iv->iov_len) { + *len = iv->iov_len - s->curoff; + return iv->iov_base + s->curoff; + } + } + *len = 0; + return NULL; +} + +static inline void skip(struct source *s, size_t n) +{ + struct iovec *iv = &s->iov[s->curvec]; + s->curoff += n; + DCHECK_LE(s->curoff, iv->iov_len); + if (s->curoff >= iv->iov_len && s->curvec + 1 < s->iovlen) { + s->curoff = 0; + s->curvec++; + } +} + +struct sink { + struct iovec *iov; + int iovlen; + unsigned curvec; + unsigned curoff; + unsigned written; +}; + +static inline void append(struct sink *s, const char *data, size_t n) +{ + struct iovec *iov = &s->iov[s->curvec]; + char *dst = iov->iov_base + s->curoff; + size_t nlen = min_t(size_t, iov->iov_len - s->curoff, n); + if (data != dst) + memcpy(dst, data, nlen); + s->written += n; + s->curoff += nlen; + while ((n -= nlen) > 0) { + data += nlen; + s->curvec++; + DCHECK_LT(s->curvec, s->iovlen); + iov++; + nlen = min_t(size_t, iov->iov_len, n); + memcpy(iov->iov_base, data, nlen); + s->curoff = nlen; + } +} + +static inline void *sink_peek(struct sink *s, size_t n) +{ + struct iovec *iov = &s->iov[s->curvec]; + if (s->curvec < iov->iov_len && iov->iov_len - s->curoff >= n) + return iov->iov_base + s->curoff; + return NULL; +} + +#else + +struct source { + const char *ptr; + size_t left; +}; + +static inline int available(struct source *s) +{ + return s->left; +} + +static inline const char *peek(struct source *s, size_t * len) +{ + *len = s->left; + return s->ptr; +} + +static inline void skip(struct source *s, size_t n) +{ + s->left -= n; + s->ptr += n; +} + +struct sink { + char *dest; +}; + +static inline void append(struct sink *s, const char *data, size_t n) +{ + if (data != s->dest) + memcpy(s->dest, data, n); + s->dest += n; +} + +#define sink_peek(s, n) sink_peek_no_sg(s) + +static inline void *sink_peek_no_sg(const struct sink *s) +{ + return s->dest; +} + +#endif + +struct writer { + char *base; + char *op; + char *op_limit; +}; + +/* Called before decompression */ +static inline void writer_set_expected_length(struct writer *w, size_t len) +{ + w->op_limit = w->op + len; +} + +/* Called after decompression */ +static inline bool writer_check_length(struct writer *w) +{ + return w->op == w->op_limit; +} + +/* + * Copy "len" bytes from "src" to "op", one byte at a time. Used for + * handling COPY operations where the input and output regions may + * overlap. For example, suppose: + * src == "ab" + * op == src + 2 + * len == 20 + * After IncrementalCopy(src, op, len), the result will have + * eleven copies of "ab" + * ababababababababababab + * Note that this does not match the semantics of either memcpy() + * or memmove(). + */ +static inline void incremental_copy(const char *src, char *op, int len) +{ + DCHECK_GT(len, 0); + do { + *op++ = *src++; + } while (--len > 0); +} + +/* + * Equivalent to IncrementalCopy except that it can write up to ten extra + * bytes after the end of the copy, and that it is faster. + * + * The main part of this loop is a simple copy of eight bytes at a time until + * we've copied (at least) the requested amount of bytes. However, if op and + * src are less than eight bytes apart (indicating a repeating pattern of + * length < 8), we first need to expand the pattern in order to get the correct + * results. For instance, if the buffer looks like this, with the eight-byte + * and patterns marked as intervals: + * + * abxxxxxxxxxxxx + * [------] src + * [------] op + * + * a single eight-byte copy from to will repeat the pattern once, + * after which we can move two bytes without moving : + * + * ababxxxxxxxxxx + * [------] src + * [------] op + * + * and repeat the exercise until the two no longer overlap. + * + * This allows us to do very well in the special case of one single byte + * repeated many times, without taking a big hit for more general cases. + * + * The worst case of extra writing past the end of the match occurs when + * op - src == 1 and len == 1; the last copy will read from byte positions + * [0..7] and write to [4..11], whereas it was only supposed to write to + * position 1. Thus, ten excess bytes. + */ + +#define kmax_increment_copy_overflow 10 + +static inline void incremental_copy_fast_path(const char *src, char *op, + int len) +{ + while (op - src < 8) { + UNALIGNED_STORE64(op, UNALIGNED_LOAD64(src)); + len -= op - src; + op += op - src; + } + while (len > 0) { + UNALIGNED_STORE64(op, UNALIGNED_LOAD64(src)); + src += 8; + op += 8; + len -= 8; + } +} + +static inline bool writer_append_from_self(struct writer *w, u32 offset, + u32 len) +{ + char *const op = w->op; + CHECK_LE(op, w->op_limit); + const u32 space_left = w->op_limit - op; + + if (op - w->base <= offset - 1u) /* -1u catches offset==0 */ + 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)); + } else { + if (space_left >= len + kmax_increment_copy_overflow) { + incremental_copy_fast_path(op - offset, op, len); + } else { + if (space_left < len) { + return false; + } + incremental_copy(op - offset, op, len); + } + } + + w->op = op + len; + return true; +} + +static inline bool writer_append(struct writer *w, const char *ip, u32 len) +{ + char *const op = w->op; + CHECK_LE(op, w->op_limit); + const u32 space_left = w->op_limit - op; + if (space_left < len) + return false; + memcpy(op, ip, len); + w->op = op + len; + return true; +} + +static inline bool writer_try_fast_append(struct writer *w, const char *ip, + u32 available_bytes, u32 len) +{ + char *const op = w->op; + const int space_left = w->op_limit - op; + if (len <= 16 && available_bytes >= 16 && space_left >= 16) { + /* Fast path, used for the majority (~95%) of invocations */ + UNALIGNED_STORE64(op, UNALIGNED_LOAD64(ip)); + UNALIGNED_STORE64(op + 8, UNALIGNED_LOAD64(ip + 8)); + w->op = op + len; + return true; + } + return false; +} + +/* + * Any hash function will produce a valid compressed bitstream, but a good + * hash function reduces the number of collisions and thus yields better + * compression for compressible input, and more speed for incompressible + * input. Of course, it doesn't hurt if the hash function is reasonably fast + * either, as it gets called a lot. + */ +static inline u32 hash_bytes(u32 bytes, int shift) +{ + u32 kmul = 0x1e35a7bd; + return (bytes * kmul) >> shift; +} + +static inline u32 hash(const char *p, int shift) +{ + return hash_bytes(UNALIGNED_LOAD32(p), shift); +} + +/* + * Compressed data can be defined as: + * compressed := item* literal* + * item := literal* copy + * + * The trailing literal sequence has a space blowup of at most 62/60 + * since a literal of length 60 needs one tag byte + one extra byte + * for length information. + * + * Item blowup is trickier to measure. Suppose the "copy" op copies + * 4 bytes of data. Because of a special check in the encoding code, + * we produce a 4-byte copy only if the offset is < 65536. Therefore + * the copy op takes 3 bytes to encode, and this type of item leads + * to at most the 62/60 blowup for representing literals. + * + * Suppose the "copy" op copies 5 bytes of data. If the offset is big + * enough, it will take 5 bytes to encode the copy op. Therefore the + * worst case here is a one-byte literal followed by a five-byte copy. + * I.e., 6 bytes of input turn into 7 bytes of "compressed" data. + * + * This last factor dominates the blowup, so the final estimate is: + */ +size_t snappy_max_compressed_length(size_t source_len) +{ + return 32 + source_len + source_len / 6; +} +EXPORT_SYMBOL(snappy_max_compressed_length); + +enum { + LITERAL = 0, + COPY_1_BYTE_OFFSET = 1, /* 3 bit length + 3 bits of offset in opcode */ + COPY_2_BYTE_OFFSET = 2, + COPY_4_BYTE_OFFSET = 3 +}; + +static inline char *emit_literal(char *op, + const char *literal, + int len, bool allow_fast_path) +{ + int n = len - 1; /* Zero-length literals are disallowed */ + + if (n < 60) { + /* Fits in tag byte */ + *op++ = LITERAL | (n << 2); + +/* + * The vast majority of copies are below 16 bytes, for which a + * call to memcpy is overkill. This fast path can sometimes + * copy up to 15 bytes too much, but that is okay in the + * main loop, since we have a bit to go on for both sides: + * + * - The input will always have kInputMarginBytes = 15 extra + * available bytes, as long as we're in the main loop, and + * if not, allow_fast_path = false. + * - 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)); + return op + len; + } + } else { + /* Encode in upcoming bytes */ + char *base = op; + int count = 0; + op++; + while (n > 0) { + *op++ = n & 0xff; + n >>= 8; + count++; + } + DCHECK(count >= 1); + DCHECK(count <= 4); + *base = LITERAL | ((59 + count) << 2); + } + memcpy(op, literal, len); + return op + len; +} + +static inline char *emit_copy_less_than64(char *op, int offset, int len) +{ + DCHECK_LE(len, 64); + DCHECK_GE(len, 4); + DCHECK_LT(offset, 65536); + + if ((len < 12) && (offset < 2048)) { + int len_minus_4 = len - 4; + DCHECK(len_minus_4 < 8); /* Must fit in 3 bits */ + *op++ = + COPY_1_BYTE_OFFSET | ((len_minus_4) << 2) | ((offset >> 8) + << 5); + *op++ = offset & 0xff; + } else { + *op++ = COPY_2_BYTE_OFFSET | ((len - 1) << 2); + put_unaligned_le16(offset, op); + op += 2; + } + return op; +} + +static inline char *emit_copy(char *op, int offset, int len) +{ + /* + * Emit 64 byte copies but make sure to keep at least four bytes + * reserved + */ + while (len >= 68) { + op = emit_copy_less_than64(op, offset, 64); + len -= 64; + } + + /* + * Emit an extra 60 byte copy if have too much data to fit in + * one copy + */ + if (len > 64) { + op = emit_copy_less_than64(op, offset, 60); + len -= 60; + } + + /* Emit remainder */ + op = emit_copy_less_than64(op, offset, len); + return op; +} + +/** + * snappy_uncompressed_length - return length of uncompressed output. + * @start: compressed buffer + * @n: length of compressed buffer. + * @result: Write the length of the uncompressed output here. + * + * Returns true when successfull, otherwise false. + */ +bool snappy_uncompressed_length(const char *start, size_t n, size_t * result) +{ + u32 v = 0; + const char *limit = start + n; + if (varint_parse32_with_limit(start, limit, &v) != NULL) { + *result = v; + return true; + } else { + return false; + } +} +EXPORT_SYMBOL(snappy_uncompressed_length); + +#define kblock_log 15 +#define kblock_size (1 << kblock_log) + +/* + * This value could be halfed or quartered to save memory + * at the cost of slightly worse compression. + */ +#define kmax_hash_table_bits 14 +#define kmax_hash_table_size (1U << kmax_hash_table_bits) + +/* + * Use smaller hash table when input.size() is smaller, since we + * fill the table, incurring O(hash table size) overhead for + * compression, and if the input is short, we won't need that + * many hash table entries anyway. + */ +static u16 *get_hash_table(struct snappy_env *env, size_t input_size, + int *table_size) +{ + unsigned htsize = 256; + + DCHECK(kmax_hash_table_size >= 256); + while (htsize < kmax_hash_table_size && htsize < input_size) + htsize <<= 1; + CHECK_EQ(0, htsize & (htsize - 1)); + CHECK_LE(htsize, kmax_hash_table_size); + + u16 *table; + table = env->hash_table; + + *table_size = htsize; + memset(table, 0, htsize * sizeof(*table)); + return table; +} + +/* + * Return the largest n such that + * + * s1[0,n-1] == s2[0,n-1] + * and n <= (s2_limit - s2). + * + * Does not read *s2_limit or beyond. + * Does not read *(s1 + (s2_limit - s2)) or beyond. + * Requires that s2_limit >= s2. + * + * Separate implementation for x86_64, for speed. Uses the fact that + * x86_64 is little endian. + */ +#if defined(__LITTLE_ENDIAN__) && BITS_PER_LONG == 64 +static inline int find_match_length(const char *s1, + const char *s2, const char *s2_limit) +{ + int matched = 0; + + DCHECK_GE(s2_limit, s2); + /* + * Find out how long the match is. We loop over the data 64 bits at a + * time until we find a 64-bit block that doesn't match; then we find + * the first non-matching bit and use that to calculate the total + * length of the match. + */ + while (likely(s2 <= s2_limit - 8)) { + if (unlikely + (UNALIGNED_LOAD64(s2) == UNALIGNED_LOAD64(s1 + matched))) { + s2 += 8; + matched += 8; + } else { + /* + * On current (mid-2008) Opteron models there + * is a 3% more efficient code sequence to + * find the first non-matching byte. However, + * what follows is ~10% better on Intel Core 2 + * and newer, and we expect AMD's bsf + * instruction to improve. + */ + u64 x = + UNALIGNED_LOAD64(s2) ^ UNALIGNED_LOAD64(s1 + + matched); + int matching_bits = find_lsb_set_non_zero64(x); + matched += matching_bits >> 3; + return matched; + } + } + while (likely(s2 < s2_limit)) { + if (likely(s1[matched] == *s2)) { + ++s2; + ++matched; + } else { + return matched; + } + } + return matched; +} +#else +static inline int find_match_length(const char *s1, + const char *s2, const char *s2_limit) +{ + /* Implementation based on the x86-64 version, above. */ + DCHECK_GE(s2_limit, s2); + int matched = 0; + + while (s2 <= s2_limit - 4 && + UNALIGNED_LOAD32(s2) == UNALIGNED_LOAD32(s1 + matched)) { + s2 += 4; + matched += 4; + } + if (is_little_endian() && s2 <= s2_limit - 4) { + u32 x = + UNALIGNED_LOAD32(s2) ^ UNALIGNED_LOAD32(s1 + matched); + int matching_bits = find_lsb_set_non_zero(x); + matched += matching_bits >> 3; + } else { + while ((s2 < s2_limit) && (s1[matched] == *s2)) { + ++s2; + ++matched; + } + } + return matched; +} +#endif + +/* + * For 0 <= offset <= 4, GetU32AtOffset(UNALIGNED_LOAD64(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 u32. + */ +static inline u32 get_u32_at_offset(u64 v, int offset) +{ + DCHECK(0 <= offset && offset <= 4); + return v >> (is_little_endian()? 8 * offset : 32 - 8 * offset); +} + +/* + * Flat array compression that does not emit the "uncompressed length" + * prefix. Compresses "input" string to the "*op" buffer. + * + * REQUIRES: "input" is at most "kBlockSize" bytes long. + * REQUIRES: "op" points to an array of memory that is at least + * "MaxCompressedLength(input.size())" in size. + * REQUIRES: All elements in "table[0..table_size-1]" are initialized to zero. + * REQUIRES: "table_size" is a power of two + * + * Returns an "end" pointer into "op" buffer. + * "end - op" is the compressed size of "input". + */ + +static char *compress_fragment(const char *const input, + const size_t input_size, + char *op, u16 * table, const unsigned table_size) +{ + /* "ip" is the input pointer, and "op" is the output pointer. */ + const char *ip = input; + CHECK_LE(input_size, kblock_size); + CHECK_EQ(table_size & (table_size - 1), 0); + const int shift = 32 - log2_floor(table_size); + DCHECK_EQ(UINT_MAX >> shift, table_size - 1); + const char *ip_end = input + input_size; + const char *baseip = 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 unsigned kinput_margin_bytes = 15; + + if (likely(input_size >= kinput_margin_bytes)) { + const char *const ip_limit = input + input_size - + kinput_margin_bytes; + + u32 next_hash; + for (next_hash = hash(++ip, shift);;) { + DCHECK_LT(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.) + * + * In the first iteration of this loop we're just starting, so + * there's nothing to copy, so calling EmitLiteral once is + * necessary. And we only start a new iteration when the + * current iteration has determined that a call to EmitLiteral will + * precede the next call to EmitCopy (if any). + * + * Step 1: Scan forward in the input looking for a 4-byte-long match. + * If we get close to exhausting the input then goto emit_remainder. + * + * Heuristic match skipping: If 32 bytes are scanned with no matches + * found, start looking only at every other byte. If 32 more bytes are + * scanned, look at every third byte, etc.. When a match is found, + * immediately go back to looking at every byte. This is a small loss + * (~5% performance, ~0.1% density) for lcompressible data due to more + * bookkeeping, but for non-compressible data (such as JPEG) it's a huge + * win since the compressor quickly "realizes" the data is incompressible + * and doesn't bother looking for matches everywhere. + * + * The "skip" variable keeps track of how many bytes there are since the + * last match; dividing it by 32 (ie. right-shifting by five) gives the + * number of bytes to move ahead for each iteration. + */ + u32 skip_bytes = 32; + + const char *next_ip = ip; + const char *candidate; + do { + ip = next_ip; + u32 hval = next_hash; + DCHECK_EQ(hval, hash(ip, shift)); + u32 bytes_between_hash_lookups = skip_bytes++ >> 5; + next_ip = ip + bytes_between_hash_lookups; + if (unlikely(next_ip > ip_limit)) { + goto emit_remainder; + } + next_hash = hash(next_ip, shift); + candidate = baseip + table[hval]; + DCHECK_GE(candidate, baseip); + DCHECK_LT(candidate, ip); + + table[hval] = ip - baseip; + } while (likely(UNALIGNED_LOAD32(ip) != + UNALIGNED_LOAD32(candidate))); + +/* + * 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); + op = emit_literal(op, next_emit, ip - next_emit, true); + +/* + * Step 3: Call EmitCopy, and then see if another EmitCopy could + * be our next move. Repeat until we find no match for the + * input immediately after what was consumed by the last EmitCopy call. + * + * If we exit this loop normally then we need to call EmitLiteral next, + * 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. + */ + u64 input_bytes = 0; + u32 candidate_bytes = 0; + + do { +/* + * We have a 4-byte match at ip, and no need to emit any + * "literal bytes" prior to ip. + */ + const char *base = ip; + int matched = 4 + + find_match_length(candidate + 4, ip + 4, + ip_end); + ip += matched; + int offset = base - candidate; + DCHECK_EQ(0, memcmp(base, candidate, matched)); + op = emit_copy(op, offset, matched); +/* + * We could immediately start working at ip now, but to improve + * compression we first update table[Hash(ip - 1, ...)]. + */ + const char *insert_tail = ip - 1; + next_emit = ip; + if (unlikely(ip >= ip_limit)) { + goto emit_remainder; + } + input_bytes = UNALIGNED_LOAD64(insert_tail); + u32 prev_hash = + hash_bytes(get_u32_at_offset + (input_bytes, 0), shift); + table[prev_hash] = ip - baseip - 1; + u32 cur_hash = + hash_bytes(get_u32_at_offset + (input_bytes, 1), shift); + candidate = baseip + table[cur_hash]; + candidate_bytes = UNALIGNED_LOAD32(candidate); + table[cur_hash] = ip - baseip; + } while (get_u32_at_offset(input_bytes, 1) == + candidate_bytes); + + next_hash = + hash_bytes(get_u32_at_offset(input_bytes, 2), + shift); + ++ip; + } + } + +emit_remainder: + /* Emit the remaining bytes as a literal */ + if (next_emit < ip_end) + op = emit_literal(op, next_emit, ip_end - next_emit, false); + + return op; +} + +/* + * ----------------------------------------------------------------------- + * Lookup table for decompression code. Generated by ComputeTable() below. + * ----------------------------------------------------------------------- + */ + +/* Mapping from i in range [0,4] to a mask to extract the bottom 8*i bits */ +static const u32 wordmask[] = { + 0u, 0xffu, 0xffffu, 0xffffffu, 0xffffffffu +}; + +/* + * Data stored per entry in lookup table: + * Range Bits-used Description + * ------------------------------------ + * 1..64 0..7 Literal/copy length encoded in opcode byte + * 0..7 8..10 Copy offset encoded in opcode byte / 256 + * 0..4 11..13 Extra bytes after opcode + * + * We use eight bits for the length even though 7 would have sufficed + * because of efficiency reasons: + * (1) Extracting a byte is faster than a bit-field + * (2) It properly aligns copy offset so we do not need a <<8 + */ +static const u16 char_table[256] = { + 0x0001, 0x0804, 0x1001, 0x2001, 0x0002, 0x0805, 0x1002, 0x2002, + 0x0003, 0x0806, 0x1003, 0x2003, 0x0004, 0x0807, 0x1004, 0x2004, + 0x0005, 0x0808, 0x1005, 0x2005, 0x0006, 0x0809, 0x1006, 0x2006, + 0x0007, 0x080a, 0x1007, 0x2007, 0x0008, 0x080b, 0x1008, 0x2008, + 0x0009, 0x0904, 0x1009, 0x2009, 0x000a, 0x0905, 0x100a, 0x200a, + 0x000b, 0x0906, 0x100b, 0x200b, 0x000c, 0x0907, 0x100c, 0x200c, + 0x000d, 0x0908, 0x100d, 0x200d, 0x000e, 0x0909, 0x100e, 0x200e, + 0x000f, 0x090a, 0x100f, 0x200f, 0x0010, 0x090b, 0x1010, 0x2010, + 0x0011, 0x0a04, 0x1011, 0x2011, 0x0012, 0x0a05, 0x1012, 0x2012, + 0x0013, 0x0a06, 0x1013, 0x2013, 0x0014, 0x0a07, 0x1014, 0x2014, + 0x0015, 0x0a08, 0x1015, 0x2015, 0x0016, 0x0a09, 0x1016, 0x2016, + 0x0017, 0x0a0a, 0x1017, 0x2017, 0x0018, 0x0a0b, 0x1018, 0x2018, + 0x0019, 0x0b04, 0x1019, 0x2019, 0x001a, 0x0b05, 0x101a, 0x201a, + 0x001b, 0x0b06, 0x101b, 0x201b, 0x001c, 0x0b07, 0x101c, 0x201c, + 0x001d, 0x0b08, 0x101d, 0x201d, 0x001e, 0x0b09, 0x101e, 0x201e, + 0x001f, 0x0b0a, 0x101f, 0x201f, 0x0020, 0x0b0b, 0x1020, 0x2020, + 0x0021, 0x0c04, 0x1021, 0x2021, 0x0022, 0x0c05, 0x1022, 0x2022, + 0x0023, 0x0c06, 0x1023, 0x2023, 0x0024, 0x0c07, 0x1024, 0x2024, + 0x0025, 0x0c08, 0x1025, 0x2025, 0x0026, 0x0c09, 0x1026, 0x2026, + 0x0027, 0x0c0a, 0x1027, 0x2027, 0x0028, 0x0c0b, 0x1028, 0x2028, + 0x0029, 0x0d04, 0x1029, 0x2029, 0x002a, 0x0d05, 0x102a, 0x202a, + 0x002b, 0x0d06, 0x102b, 0x202b, 0x002c, 0x0d07, 0x102c, 0x202c, + 0x002d, 0x0d08, 0x102d, 0x202d, 0x002e, 0x0d09, 0x102e, 0x202e, + 0x002f, 0x0d0a, 0x102f, 0x202f, 0x0030, 0x0d0b, 0x1030, 0x2030, + 0x0031, 0x0e04, 0x1031, 0x2031, 0x0032, 0x0e05, 0x1032, 0x2032, + 0x0033, 0x0e06, 0x1033, 0x2033, 0x0034, 0x0e07, 0x1034, 0x2034, + 0x0035, 0x0e08, 0x1035, 0x2035, 0x0036, 0x0e09, 0x1036, 0x2036, + 0x0037, 0x0e0a, 0x1037, 0x2037, 0x0038, 0x0e0b, 0x1038, 0x2038, + 0x0039, 0x0f04, 0x1039, 0x2039, 0x003a, 0x0f05, 0x103a, 0x203a, + 0x003b, 0x0f06, 0x103b, 0x203b, 0x003c, 0x0f07, 0x103c, 0x203c, + 0x0801, 0x0f08, 0x103d, 0x203d, 0x1001, 0x0f09, 0x103e, 0x203e, + 0x1801, 0x0f0a, 0x103f, 0x203f, 0x2001, 0x0f0b, 0x1040, 0x2040 +}; + +struct snappy_decompressor { + struct source *reader; /* Underlying source of bytes to decompress */ + const char *ip; /* Points to next buffered byte */ + const char *ip_limit; /* Points just past buffered bytes */ + u32 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 */ +}; + +static void +init_snappy_decompressor(struct snappy_decompressor *d, struct source *reader) +{ + d->reader = reader; + d->ip = NULL; + d->ip_limit = NULL; + d->peeked = 0; + d->eof = false; +} + +static void exit_snappy_decompressor(struct snappy_decompressor *d) +{ + skip(d->reader, d->peeked); +} + +/* + * Read the uncompressed length stored at the start of the compressed data. + * On succcess, stores the length in *result and returns true. + * On failure, returns false. + */ +static bool read_uncompressed_length(struct snappy_decompressor *d, + u32 * result) +{ + DCHECK(d->ip == NULL); /* + * Must not have read anything yet + * Length is encoded in 1..5 bytes + */ + *result = 0; + u32 shift = 0; + while (true) { + if (shift >= 32) + return false; + size_t n; + const char *ip = peek(d->reader, &n); + if (n == 0) + return false; + const unsigned char c = *(const unsigned char *)(ip); + skip(d->reader, 1); + *result |= (u32) (c & 0x7f) << shift; + if (c < 128) { + break; + } + shift += 7; + } + return true; +} + +static bool refill_tag(struct snappy_decompressor *d); + +/* + * Process the next item found in the input. + * Returns true if successful, false on error or end of input. + */ +static void decompress_all_tags(struct snappy_decompressor *d, + struct writer *writer) +{ + const char *ip = d->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 expression based on the local + * context, which overall increases speed. + */ +#define MAYBE_REFILL() \ + if (d->ip_limit - ip < 5) { \ + d->ip = ip; \ + if (!refill_tag(d)) return; \ + ip = d->ip; \ + } + + + MAYBE_REFILL(); + for (;;) { + if (d->ip_limit - ip < 5) { + d->ip = ip; + if (!refill_tag(d)) + return; + ip = d->ip; + } + + const unsigned char c = *(const unsigned char *)(ip++); + + if ((c & 0x3) == LITERAL) { + u32 literal_length = (c >> 2) + 1; + if (writer_try_fast_append(writer, ip, d->ip_limit - ip, + literal_length)) { + DCHECK_LT(literal_length, 61); + ip += literal_length; + MAYBE_REFILL(); + continue; + } + if (unlikely(literal_length >= 61)) { + /* Long literal */ + const u32 literal_ll = literal_length - 60; + literal_length = (get_unaligned_le32(ip) & + wordmask[literal_ll]) + 1; + ip += literal_ll; + } + + u32 avail = d->ip_limit - ip; + while (avail < literal_length) { + if (!writer_append(writer, ip, avail)) + return; + literal_length -= avail; + skip(d->reader, d->peeked); + size_t n; + ip = peek(d->reader, &n); + avail = n; + d->peeked = avail; + if (avail == 0) + return; /* Premature end of input */ + d->ip_limit = ip + avail; + } + if (!writer_append(writer, ip, literal_length)) + return; + ip += literal_length; + MAYBE_REFILL(); + } else { + const u32 entry = char_table[c]; + const u32 trailer = get_unaligned_le32(ip) & + wordmask[entry >> 11]; + const u32 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). + */ + const u32 copy_offset = entry & 0x700; + if (!writer_append_from_self(writer, + copy_offset + trailer, + length)) + return; + MAYBE_REFILL(); + } + } +} + +#undef MAYBE_REFILL + +static bool refill_tag(struct snappy_decompressor *d) +{ + const char *ip = d->ip; + + if (ip == d->ip_limit) { + size_t n; + /* Fetch a new fragment from the reader */ + skip(d->reader, d->peeked); /* All peeked bytes are used up */ + ip = peek(d->reader, &n); + d->peeked = n; + if (n == 0) { + d->eof = true; + return false; + } + d->ip_limit = ip + n; + } + + /* Read the tag character */ + DCHECK_LT(ip, d->ip_limit); + const unsigned char c = *(const unsigned char *)(ip); + const u32 entry = char_table[c]; + const u32 needed = (entry >> 11) + 1; /* +1 byte for 'c' */ + DCHECK_LE(needed, sizeof(d->scratch)); + + /* Read more bytes from reader if needed */ + u32 nbuf = d->ip_limit - ip; + + if (nbuf < needed) { + /* + * Stitch together bytes from ip and reader to form the word + * contents. We store the needed bytes in "scratch". They + * will be consumed immediately by the caller since we do not + * read more than we need. + */ + memmove(d->scratch, ip, nbuf); + skip(d->reader, d->peeked); /* All peeked bytes are used up */ + d->peeked = 0; + while (nbuf < needed) { + size_t length; + const char *src = peek(d->reader, &length); + if (length == 0) + return false; + u32 to_add = min_t(u32, needed - nbuf, length); + memcpy(d->scratch + nbuf, src, to_add); + nbuf += to_add; + skip(d->reader, to_add); + } + DCHECK_EQ(nbuf, needed); + d->ip = d->scratch; + d->ip_limit = d->scratch + needed; + } else if (nbuf < 5) { + /* + * Have enough bytes, but move into scratch so that we do not + * read past end of input + */ + memmove(d->scratch, ip, nbuf); + skip(d->reader, d->peeked); /* All peeked bytes are used up */ + d->peeked = 0; + d->ip = d->scratch; + d->ip_limit = d->scratch + nbuf; + } else { + /* Pass pointer to buffer returned by reader. */ + d->ip = ip; + } + return true; +} + +static int internal_uncompress(struct source *r, + struct writer *writer, u32 max_len) +{ + struct snappy_decompressor decompressor; + u32 uncompressed_len = 0; + + init_snappy_decompressor(&decompressor, r); + + if (!read_uncompressed_length(&decompressor, &uncompressed_len)) + return -EIO; + /* Protect against possible DoS attack */ + if ((u64) (uncompressed_len) > max_len) + return -EIO; + + writer_set_expected_length(writer, uncompressed_len); + + /* Process the entire input */ + decompress_all_tags(&decompressor, writer); + + exit_snappy_decompressor(&decompressor); + return (decompressor.eof && writer_check_length(writer)) ? 0 : -EIO; +} + +static inline int compress(struct snappy_env *env, struct source *reader, + struct sink *writer) +{ + int err; + size_t written = 0; + int N = available(reader); + char ulength[kmax32]; + char *p = varint_encode32(ulength, N); + + append(writer, ulength, p - ulength); + written += (p - ulength); + + while (N > 0) { + /* Get next block to compress (without copying if possible) */ + size_t fragment_size; + const char *fragment = peek(reader, &fragment_size); + if (fragment_size == 0) { + err = -EIO; + goto out; + } + const unsigned num_to_read = min_t(int, N, kblock_size); + size_t bytes_read = fragment_size; + + int pending_advance = 0; + if (bytes_read >= num_to_read) { + /* Buffer returned by reader is large enough */ + pending_advance = num_to_read; + fragment_size = num_to_read; + } + else { + memcpy(env->scratch, fragment, bytes_read); + skip(reader, bytes_read); + + while (bytes_read < num_to_read) { + fragment = peek(reader, &fragment_size); + size_t n = + min_t(size_t, fragment_size, + num_to_read - bytes_read); + memcpy((char *)(env->scratch) + bytes_read, fragment, n); + bytes_read += n; + skip(reader, n); + } + DCHECK_EQ(bytes_read, num_to_read); + fragment = env->scratch; + fragment_size = num_to_read; + } + if (fragment_size < num_to_read) + return -EIO; + + /* Get encoding table for compression */ + int table_size; + u16 *table = get_hash_table(env, num_to_read, &table_size); + + /* Compress input_fragment and append to dest */ + char *dest; + dest = sink_peek(writer, snappy_max_compressed_length(num_to_read)); + if (!dest) { + /* + * Need a scratch buffer for the output, + * because the byte sink doesn't have enough + * in one piece. + */ + dest = env->scratch_output; + } + char *end = compress_fragment(fragment, fragment_size, + dest, table, table_size); + append(writer, dest, end - dest); + written += (end - dest); + + N -= num_to_read; + skip(reader, pending_advance); + } + + err = 0; +out: + return err; +} + +#ifdef SG + +int snappy_compress_iov(struct snappy_env *env, + struct iovec *iov_in, + int iov_in_len, + size_t input_length, + struct iovec *iov_out, + int *iov_out_len, + size_t *compressed_length) +{ + struct source reader = { + .iov = iov_in, + .iovlen = iov_in_len, + .total = input_length + }; + struct sink writer = { + .iov = iov_out, + .iovlen = *iov_out_len, + }; + int err = compress(env, &reader, &writer); + + *iov_out_len = writer.curvec + 1; + + /* Compute how many bytes were added */ + *compressed_length = writer.written; + return err; +} +EXPORT_SYMBOL(snappy_compress_iov); + +/** + * snappy_compress - Compress a buffer using the snappy compressor. + * @env: Preallocated environment + * @input: Input buffer + * @input_length: Length of input_buffer + * @compressed: Output buffer for compressed data + * @compressed_length: The real length of the output written here. + * + * Return 0 on success, otherwise an negative error code. + * + * The output buffer must be at least + * snappy_max_compressed_length(input_length) bytes long. + * + * Requires a preallocated environment from snappy_init_env. + * The environment does not keep state over individual calls + * of this function, just preallocates the memory. + */ +int snappy_compress(struct snappy_env *env, + const char *input, + size_t input_length, + char *compressed, size_t *compressed_length) +{ + struct iovec iov_in = { + .iov_base = (char *)input, + .iov_len = input_length, + }; + struct iovec iov_out = { + .iov_base = compressed, + .iov_len = 0xffffffff, + }; + int out = 1; + return snappy_compress_iov(env, + &iov_in, 1, input_length, + &iov_out, &out, compressed_length); +} +EXPORT_SYMBOL(snappy_compress); + +int snappy_uncompress_iov(struct iovec *iov_in, int iov_in_len, + size_t input_len, char *uncompressed) +{ + struct source reader = { + .iov = iov_in, + .iovlen = iov_in_len, + .total = input_len + }; + struct writer output = { + .base = uncompressed, + .op = uncompressed + }; + return internal_uncompress(&reader, &output, 0xffffffff); +} +EXPORT_SYMBOL(snappy_uncompress_iov); + +/** + * snappy_uncompress - Uncompress a snappy compressed buffer + * @compressed: Input buffer with compressed data + * @n: length of compressed buffer + * @uncompressed: buffer for uncompressed data + * + * The uncompressed data buffer must be at least + * snappy_uncompressed_length(compressed) bytes long. + * + * Return 0 on success, otherwise an negative error code. + */ +int snappy_uncompress(const char *compressed, size_t n, char *uncompressed) +{ + struct iovec iov = { + .iov_base = (char *)compressed, + .iov_len = n + }; + return snappy_uncompress_iov(&iov, 1, n, uncompressed); +} +EXPORT_SYMBOL(snappy_uncompress); + +#else +/** + * snappy_compress - Compress a buffer using the snappy compressor. + * @env: Preallocated environment + * @input: Input buffer + * @input_length: Length of input_buffer + * @compressed: Output buffer for compressed data + * @compressed_length: The real length of the output written here. + * + * Return 0 on success, otherwise an negative error code. + * + * The output buffer must be at least + * snappy_max_compressed_length(input_length) bytes long. + * + * Requires a preallocated environment from snappy_init_env. + * The environment does not keep state over individual calls + * of this function, just preallocates the memory. + */ +int snappy_compress(struct snappy_env *env, + const char *input, + size_t input_length, + char *compressed, size_t *compressed_length) +{ + struct source reader = { + .ptr = input, + .left = input_length + }; + struct sink writer = { + .dest = compressed, + }; + int err = compress(env, &reader, &writer); + + /* Compute how many bytes were added */ + *compressed_length = (writer.dest - compressed); + return err; +} +EXPORT_SYMBOL(snappy_compress); + +/** + * snappy_uncompress - Uncompress a snappy compressed buffer + * @compressed: Input buffer with compressed data + * @n: length of compressed buffer + * @uncompressed: buffer for uncompressed data + * + * The uncompressed data buffer must be at least + * snappy_uncompressed_length(compressed) bytes long. + * + * Return 0 on success, otherwise an negative error code. + */ +int snappy_uncompress(const char *compressed, size_t n, char *uncompressed) +{ + struct source reader = { + .ptr = compressed, + .left = n + }; + struct writer output = { + .base = uncompressed, + .op = uncompressed + }; + return internal_uncompress(&reader, &output, 0xffffffff); +} +EXPORT_SYMBOL(snappy_uncompress); +#endif + +#ifdef SG +/** + * snappy_init_env_sg - Allocate snappy compression environment + * @env: Environment to preallocate + * @sg: Input environment ever does scather gather + * + * If false is passed to sg then multiple entries in an iovec + * are not legal. + * Returns 0 on success, otherwise negative errno. + * Must run in process context. + */ +int snappy_init_env_sg(struct snappy_env *env, bool sg) +{ + env->hash_table = vmalloc(sizeof(u16) * kmax_hash_table_size); + if (!env->hash_table) + goto error; + if (sg) { + env->scratch = vmalloc(kblock_size); + if (!env->scratch) + goto error; + env->scratch_output = + vmalloc(snappy_max_compressed_length(kblock_size)); + if (!env->scratch_output) + goto error; + } + return 0; +error: + snappy_free_env(env); + return -ENOMEM; +} +EXPORT_SYMBOL(snappy_init_env_sg); +#endif + +/** + * snappy_init_env - Allocate snappy compression environment + * @env: Environment to preallocate + * + * Passing multiple entries in an iovec is not allowed + * on the environment allocated here. + * Returns 0 on success, otherwise negative errno. + * Must run in process context. + */ +int snappy_init_env(struct snappy_env *env) +{ + env->hash_table = vmalloc(sizeof(u16) * kmax_hash_table_size); + if (!env->hash_table) + return -ENOMEM; + return 0; +} +EXPORT_SYMBOL(snappy_init_env); + +/** + * snappy_free_env - Free an snappy compression environment + * @env: Environment to free. + * + * Must run in process context. + */ +void snappy_free_env(struct snappy_env *env) +{ + vfree(env->hash_table); +#ifdef SG + vfree(env->scratch); + vfree(env->scratch_output); +#endif + memset(env, 0, sizeof(struct snappy_env)); +} +EXPORT_SYMBOL(snappy_free_env); diff --git a/src/include/common/snappy/snappy.h b/src/include/common/snappy/snappy.h new file mode 100644 index 0000000..f650f03 --- /dev/null +++ b/src/include/common/snappy/snappy.h @@ -0,0 +1,34 @@ +#ifndef _LINUX_SNAPPY_H +#define _LINUX_SNAPPY_H 1 + +/* Only needed for compression. This preallocates the worst case */ +struct snappy_env { + unsigned short *hash_table; + void *scratch; + void *scratch_output; +}; + +struct iovec; +int snappy_init_env(struct snappy_env *env); +int snappy_init_env_sg(struct snappy_env *env, bool sg); +void snappy_free_env(struct snappy_env *env); +int snappy_uncompress_iov(struct iovec *iov_in, int iov_in_len, + size_t input_len, char *uncompressed); +int snappy_uncompress(const char *compressed, size_t n, char *uncompressed); +int snappy_compress(struct snappy_env *env, + const char *input, + size_t input_length, + char *compressed, + size_t *compressed_length); +int snappy_compress_iov(struct snappy_env *env, + struct iovec *iov_in, + int iov_in_len, + size_t input_length, + struct iovec *iov_out, + int *iov_out_len, + size_t *compressed_length); +bool snappy_uncompressed_length(const char *buf, size_t len, size_t *result); +size_t snappy_max_compressed_length(size_t source_len); + + +#endif -- 1.7.10.4