diff options
Diffstat (limited to 'third_party/cachunker/src/cachunker.c')
| -rw-r--r-- | third_party/cachunker/src/cachunker.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/third_party/cachunker/src/cachunker.c b/third_party/cachunker/src/cachunker.c new file mode 100644 index 0000000..4c3b580 --- /dev/null +++ b/third_party/cachunker/src/cachunker.c @@ -0,0 +1,196 @@ +/* SPDX-FileCopyrightText: Lennart Poettering <lennart@poettering.net> */ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <math.h> +#include <string.h> +#include <assert.h> +#include <errno.h> + +#include "cachunker.h" + +/* The hardcoded, maximum chunk size, after which we refuse operation */ +#define CA_CHUNK_SIZE_LIMIT_MAX ((size_t) (128U*1024U*1024U)) +#define CA_CHUNK_SIZE_LIMIT_MIN ((size_t) 1) + +static inline uint32_t rol32(uint32_t x, size_t i) { + i %= 32; + + if (i == 0) /* Make ubsan happy */ + return x; + + return ((x) << (i)) | ((x) >> (32 - i)); +} + +static const uint32_t buzhash_table[] = { + 0x458be752, 0xc10748cc, 0xfbbcdbb8, 0x6ded5b68, + 0xb10a82b5, 0x20d75648, 0xdfc5665f, 0xa8428801, + 0x7ebf5191, 0x841135c7, 0x65cc53b3, 0x280a597c, + 0x16f60255, 0xc78cbc3e, 0x294415f5, 0xb938d494, + 0xec85c4e6, 0xb7d33edc, 0xe549b544, 0xfdeda5aa, + 0x882bf287, 0x3116737c, 0x05569956, 0xe8cc1f68, + 0x0806ac5e, 0x22a14443, 0x15297e10, 0x50d090e7, + 0x4ba60f6f, 0xefd9f1a7, 0x5c5c885c, 0x82482f93, + 0x9bfd7c64, 0x0b3e7276, 0xf2688e77, 0x8fad8abc, + 0xb0509568, 0xf1ada29f, 0xa53efdfe, 0xcb2b1d00, + 0xf2a9e986, 0x6463432b, 0x95094051, 0x5a223ad2, + 0x9be8401b, 0x61e579cb, 0x1a556a14, 0x5840fdc2, + 0x9261ddf6, 0xcde002bb, 0x52432bb0, 0xbf17373e, + 0x7b7c222f, 0x2955ed16, 0x9f10ca59, 0xe840c4c9, + 0xccabd806, 0x14543f34, 0x1462417a, 0x0d4a1f9c, + 0x087ed925, 0xd7f8f24c, 0x7338c425, 0xcf86c8f5, + 0xb19165cd, 0x9891c393, 0x325384ac, 0x0308459d, + 0x86141d7e, 0xc922116a, 0xe2ffa6b6, 0x53f52aed, + 0x2cd86197, 0xf5b9f498, 0xbf319c8f, 0xe0411fae, + 0x977eb18c, 0xd8770976, 0x9833466a, 0xc674df7f, + 0x8c297d45, 0x8ca48d26, 0xc49ed8e2, 0x7344f874, + 0x556f79c7, 0x6b25eaed, 0xa03e2b42, 0xf68f66a4, + 0x8e8b09a2, 0xf2e0e62a, 0x0d3a9806, 0x9729e493, + 0x8c72b0fc, 0x160b94f6, 0x450e4d3d, 0x7a320e85, + 0xbef8f0e1, 0x21d73653, 0x4e3d977a, 0x1e7b3929, + 0x1cc6c719, 0xbe478d53, 0x8d752809, 0xe6d8c2c6, + 0x275f0892, 0xc8acc273, 0x4cc21580, 0xecc4a617, + 0xf5f7be70, 0xe795248a, 0x375a2fe9, 0x425570b6, + 0x8898dcf8, 0xdc2d97c4, 0x0106114b, 0x364dc22f, + 0x1e0cad1f, 0xbe63803c, 0x5f69fac2, 0x4d5afa6f, + 0x1bc0dfb5, 0xfb273589, 0x0ea47f7b, 0x3c1c2b50, + 0x21b2a932, 0x6b1223fd, 0x2fe706a8, 0xf9bd6ce2, + 0xa268e64e, 0xe987f486, 0x3eacf563, 0x1ca2018c, + 0x65e18228, 0x2207360a, 0x57cf1715, 0x34c37d2b, + 0x1f8f3cde, 0x93b657cf, 0x31a019fd, 0xe69eb729, + 0x8bca7b9b, 0x4c9d5bed, 0x277ebeaf, 0xe0d8f8ae, + 0xd150821c, 0x31381871, 0xafc3f1b0, 0x927db328, + 0xe95effac, 0x305a47bd, 0x426ba35b, 0x1233af3f, + 0x686a5b83, 0x50e072e5, 0xd9d3bb2a, 0x8befc475, + 0x487f0de6, 0xc88dff89, 0xbd664d5e, 0x971b5d18, + 0x63b14847, 0xd7d3c1ce, 0x7f583cf3, 0x72cbcb09, + 0xc0d0a81c, 0x7fa3429b, 0xe9158a1b, 0x225ea19a, + 0xd8ca9ea3, 0xc763b282, 0xbb0c6341, 0x020b8293, + 0xd4cd299d, 0x58cfa7f8, 0x91b4ee53, 0x37e4d140, + 0x95ec764c, 0x30f76b06, 0x5ee68d24, 0x679c8661, + 0xa41979c2, 0xf2b61284, 0x4fac1475, 0x0adb49f9, + 0x19727a23, 0x15a7e374, 0xc43a18d5, 0x3fb1aa73, + 0x342fc615, 0x924c0793, 0xbee2d7f0, 0x8a279de9, + 0x4aa2d70c, 0xe24dd37f, 0xbe862c0b, 0x177c22c2, + 0x5388e5ee, 0xcd8a7510, 0xf901b4fd, 0xdbc13dbc, + 0x6c0bae5b, 0x64efe8c7, 0x48b02079, 0x80331a49, + 0xca3d8ae6, 0xf3546190, 0xfed7108b, 0xc49b941b, + 0x32baf4a9, 0xeb833a4a, 0x88a3f1a5, 0x3a91ce0a, + 0x3cc27da1, 0x7112e684, 0x4a3096b1, 0x3794574c, + 0xa3c8b6f3, 0x1d213941, 0x6e0a2e00, 0x233479f1, + 0x0f4cd82f, 0x6093edd2, 0x5d7d209e, 0x464fe319, + 0xd4dcac9e, 0x0db845cb, 0xfb5e4bc3, 0xe0256ce1, + 0x09fb4ed1, 0x0914be1e, 0xa5bdb2c3, 0xc6eb57bb, + 0x30320350, 0x3f397e91, 0xa67791bc, 0x86bc0e2c, + 0xefa0a7e2, 0xe9ff7543, 0xe733612c, 0xd185897b, + 0x329e5388, 0x91dd236b, 0x2ecb0d93, 0xf4d82a3d, + 0x35b5c03f, 0xe4e606f0, 0x05b21843, 0x37b45964, + 0x5eff22f4, 0x6027f4cc, 0x77178b3c, 0xae507131, + 0x7bf7cabc, 0xf9c18d66, 0x593ade65, 0xd95ddf11, +}; + +CaChunker ca_chunker_init = CA_CHUNKER_INIT; + +uint32_t ca_chunker_start(CaChunker *c, const void *p, size_t n) { + const uint8_t *q = p; + size_t i; + + assert(c); + + assert(CA_CHUNK_SIZE_LIMIT_MIN <= c->chunk_size_min); + assert(c->chunk_size_min <= c->chunk_size_avg); + assert(c->chunk_size_avg <= c->chunk_size_max); + assert(c->chunk_size_max <= CA_CHUNK_SIZE_LIMIT_MAX); + + c->window_size = n; + + for (i = 1; i < n; i++, q++) + c->h ^= rol32(buzhash_table[*q], n - i); + + c->h ^= buzhash_table[*q]; + + return c->h; +} + +uint32_t ca_chunker_roll(CaChunker *c, uint8_t leave, uint8_t enter) { + + c->h = rol32(c->h, 1) ^ + rol32(buzhash_table[leave], c->window_size) ^ + buzhash_table[enter]; + + return c->h; +} + +static bool shall_break(CaChunker *c, uint32_t v) { + assert(c); + + if (c->chunk_size >= c->chunk_size_max) + return true; + + if (c->chunk_size < c->chunk_size_min) + return false; + + return (v % c->discriminator) == (c->discriminator - 1); +} + +size_t ca_chunker_scan(CaChunker *c, const void* p, size_t n) { + const uint8_t *q = p; + uint32_t v; + size_t k = 0, idx; + + assert(c); + assert(p); + + /* Scans the specified bytes for chunk borders. Returns (size_t) -1 if no border was discovered, otherwise the + * chunk size. */ + + if (c->window_size < CA_CHUNKER_WINDOW_SIZE) { + size_t m; + + /* Append to window to make it full */ + m = CA_CHUNKER_WINDOW_SIZE - c->window_size; + if (m > n) m = n; + + memcpy(c->window + c->window_size, q, m); + q += m, n -= m; + + c->window_size += m; + c->chunk_size += m; + + /* If the window isn't full still, return early */ + if (c->window_size < CA_CHUNKER_WINDOW_SIZE) + return (size_t) -1; + + /* Window is full, we are now ready to go. */ + v = ca_chunker_start(c, c->window, c->window_size); + k = m; + + if (shall_break(c, v)) + goto now; + } + + idx = c->chunk_size % CA_CHUNKER_WINDOW_SIZE; + + while (n > 0) { + v = ca_chunker_roll(c, c->window[idx], *q); + c->chunk_size++; + k++; + + if (shall_break(c, v)) + goto now; + + c->window[idx++] = *q; + if (idx == CA_CHUNKER_WINDOW_SIZE) + idx = 0; + + q++, n--; + } + + return (size_t) -1; + +now: + c->h = 0; + c->chunk_size = 0; + c->window_size = 0; + + return k; +} |