commit 69aa0e90839745f70c6fc7e33c78bbe949f3500d from: Stefan Sperling date: Wed Mar 10 22:49:21 2021 UTC substantial rewrite of deltify.c; operate on plain files only commit - 5788893e052e36c9c54c8ab6781ed97a5fca6f91 commit + 69aa0e90839745f70c6fc7e33c78bbe949f3500d blob - ae0934bc97fbc1d6580fa4db26df7f5b13306f70 blob + 8a0eff6fcacb802bbb187c60a24de4447dc455fe --- lib/deltify.c +++ lib/deltify.c @@ -1,5 +1,6 @@ /* * Copyright (c) 2020 Ori Bernstein + * Copyright (c) 2021 Stefan Sperling * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above @@ -18,6 +19,7 @@ #include #include +#include #include #include #include @@ -26,265 +28,380 @@ #include #include "got_error.h" -#include "got_object.h" -#include "got_lib_delta.h" -#include "got_lib_object.h" +#include "got_lib_deltify.h" -struct Dblock { - unsigned char *buf; - int len; - int off; - uint64_t hash; -}; +#ifndef MIN +#define MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b)) +#endif -struct Dtab { - unsigned char *base; - int nbase; - struct Dblock *b; - int nb; - int sz; -}; - -struct Delta { - int cpy; - int off; - int len; -}; - -enum { - Minchunk = 128, - Maxchunk = 8192, - Splitmask = (1 << 8) - 1, - -}; - static uint32_t geartab[] = { - 0x67ed26b7, 0x32da500c, 0x53d0fee0, 0xce387dc7, 0xcd406d90, 0x2e83a4d4, 0x9fc9a38d, 0xb67259dc, - 0xca6b1722, 0x6d2ea08c, 0x235cea2e, 0x3149bb5f, 0x1beda787, 0x2a6b77d5, 0x2f22d9ac, 0x91fc0544, - 0xe413acfa, 0x5a30ff7a, 0xad6fdde0, 0x444fd0f5, 0x7ad87864, 0x58c5ff05, 0x8d2ec336, 0x2371f853, - 0x550f8572, 0x6aa448dd, 0x7c9ddbcf, 0x95221e14, 0x2a82ec33, 0xcbec5a78, 0xc6795a0d, 0x243995b7, - 0x1c909a2f, 0x4fded51c, 0x635d334b, 0x0e2b9999, 0x2702968d, 0x856de1d5, 0x3325d60e, 0xeb6a7502, - 0xec2a9844, 0x0905835a, 0xa1820375, 0xa4be5cab, 0x96a6c058, 0x2c2ccd70, 0xba40fce3, 0xd794c46b, - 0x8fbae83e, 0xc3aa7899, 0x3d3ff8ed, 0xa0d42b5b, 0x571c0c97, 0xd2811516, 0xf7e7b96c, 0x4fd2fcbd, - 0xe2fdec94, 0x282cc436, 0x78e8e95c, 0x80a3b613, 0xcfbee20c, 0xd4a32d1c, 0x2a12ff13, 0x6af82936, - 0xe5630258, 0x8efa6a98, 0x294fb2d1, 0xdeb57086, 0x5f0fddb3, 0xeceda7ce, 0x4c87305f, 0x3a6d3307, - 0xe22d2942, 0x9d060217, 0x1e42ed02, 0xb6f63b52, 0x4367f39f, 0x055cf262, 0x03a461b2, 0x5ef9e382, - 0x386bc03a, 0x2a1e79c7, 0xf1a0058b, 0xd4d2dea9, 0x56baf37d, 0x5daff6cc, 0xf03a951d, 0xaef7de45, - 0xa8f4581e, 0x3960b555, 0xffbfff6d, 0xbe702a23, 0x8f5b6d6f, 0x061739fb, 0x98696f47, 0x3fd596d4, - 0x151eac6b, 0xa9fcc4f5, 0x69181a12, 0x3ac5a107, 0xb5198fe7, 0x96bcb1da, 0x1b5ddf8e, 0xc757d650, - 0x65865c3a, 0x8fc0a41a, 0x87435536, 0x99eda6f2, 0x41874794, 0x29cff4e8, 0xb70efd9a, 0x3103f6e7, - 0x84d2453b, 0x15a450bd, 0x74f49af1, 0x60f664b1, 0xa1c86935, 0xfdafbce1, 0xe36353e3, 0x5d9ba739, - 0xbc0559ba, 0x708b0054, 0xd41d808c, 0xb2f31723, 0x9027c41f, 0xf136d165, 0xb5374b12, 0x9420a6ac, - 0x273958b6, 0xe6c2fad0, 0xebdc1f21, 0xfb33af8b, 0xc71c25cd, 0xe9a2d8e5, 0xbeb38a50, 0xbceb7cc2, - 0x4e4e73f0, 0xcd6c251d, 0xde4c032c, 0x4b04ac30, 0x725b8b21, 0x4eb8c33b, 0x20d07b75, 0x0567aa63, - 0xb56b2bb7, 0xc1f5fd3a, 0xcafd35ca, 0x470dd4da, 0xfe4f94cd, 0xfb8de424, 0xe8dbcf40, 0xfe50a37a, - 0x62db5b5d, 0xf32f4ab6, 0x2c4a8a51, 0x18473dc0, 0xfe0cbb6e, 0xfe399efd, 0xdf34ecc9, 0x6ccd5055, - 0x46097073, 0x139135c2, 0x721c76f6, 0x1c6a94b4, 0x6eee014d, 0x8a508e02, 0x3da538f5, 0x280d394f, - 0x5248a0c4, 0x3ce94c6c, 0x9a71ad3a, 0x8493dd05, 0xe43f0ab6, 0x18e4ed42, 0x6c5c0e09, 0x42b06ec9, - 0x8d330343, 0xa45b6f59, 0x2a573c0c, 0xd7fd3de6, 0xeedeab68, 0x5c84dafc, 0xbbd1b1a8, 0xa3ce1ad1, - 0x85b70bed, 0xb6add07f, 0xa531309c, 0x8f8ab852, 0x564de332, 0xeac9ed0c, 0x73da402c, 0x3ec52761, - 0x43af2f4d, 0xd6ff45c8, 0x4c367462, 0xd553bd6a, 0x44724855, 0x3b2aa728, 0x56e5eb65, 0xeaf16173, - 0x33fa42ff, 0xd714bb5d, 0xfbd0a3b9, 0xaf517134, 0x9416c8cd, 0x534cf94f, 0x548947c2, 0x34193569, - 0x32f4389a, 0xfe7028bc, 0xed73b1ed, 0x9db95770, 0x468e3922, 0x0440c3cd, 0x60059a62, 0x33504562, - 0x2b229fbd, 0x5174dca5, 0xf7028752, 0xd63c6aa8, 0x31276f38, 0x0646721c, 0xb0191da8, 0xe00e6de0, - 0x9eac1a6e, 0x9f7628a5, 0xed6c06ea, 0x0bb8af15, 0xf119fb12, 0x38693c1c, 0x732bc0fe, 0x84953275, - 0xb82ec888, 0x33a4f1b3, 0x3099835e, 0x028a8782, 0x5fdd51d7, 0xc6c717b3, 0xb06caf71, 0x17c8c111, - 0x61bad754, 0x9fd03061, 0xe09df1af, 0x3bc9eb73, 0x85878413, 0x9889aaf2, 0x3f5a9e46, 0x42c9f01f, - 0x9984a4f4, 0xd5de43cc, 0xd294daed, 0xbecba2d2, 0xf1f6e72c, 0x5551128a, 0x83af87e2, 0x6f0342ba, + 0x67ed26b7, 0x32da500c, 0x53d0fee0, 0xce387dc7, 0xcd406d90, 0x2e83a4d4, + 0x9fc9a38d, 0xb67259dc, 0xca6b1722, 0x6d2ea08c, 0x235cea2e, 0x3149bb5f, + 0x1beda787, 0x2a6b77d5, 0x2f22d9ac, 0x91fc0544, 0xe413acfa, 0x5a30ff7a, + 0xad6fdde0, 0x444fd0f5, 0x7ad87864, 0x58c5ff05, 0x8d2ec336, 0x2371f853, + 0x550f8572, 0x6aa448dd, 0x7c9ddbcf, 0x95221e14, 0x2a82ec33, 0xcbec5a78, + 0xc6795a0d, 0x243995b7, 0x1c909a2f, 0x4fded51c, 0x635d334b, 0x0e2b9999, + 0x2702968d, 0x856de1d5, 0x3325d60e, 0xeb6a7502, 0xec2a9844, 0x0905835a, + 0xa1820375, 0xa4be5cab, 0x96a6c058, 0x2c2ccd70, 0xba40fce3, 0xd794c46b, + 0x8fbae83e, 0xc3aa7899, 0x3d3ff8ed, 0xa0d42b5b, 0x571c0c97, 0xd2811516, + 0xf7e7b96c, 0x4fd2fcbd, 0xe2fdec94, 0x282cc436, 0x78e8e95c, 0x80a3b613, + 0xcfbee20c, 0xd4a32d1c, 0x2a12ff13, 0x6af82936, 0xe5630258, 0x8efa6a98, + 0x294fb2d1, 0xdeb57086, 0x5f0fddb3, 0xeceda7ce, 0x4c87305f, 0x3a6d3307, + 0xe22d2942, 0x9d060217, 0x1e42ed02, 0xb6f63b52, 0x4367f39f, 0x055cf262, + 0x03a461b2, 0x5ef9e382, 0x386bc03a, 0x2a1e79c7, 0xf1a0058b, 0xd4d2dea9, + 0x56baf37d, 0x5daff6cc, 0xf03a951d, 0xaef7de45, 0xa8f4581e, 0x3960b555, + 0xffbfff6d, 0xbe702a23, 0x8f5b6d6f, 0x061739fb, 0x98696f47, 0x3fd596d4, + 0x151eac6b, 0xa9fcc4f5, 0x69181a12, 0x3ac5a107, 0xb5198fe7, 0x96bcb1da, + 0x1b5ddf8e, 0xc757d650, 0x65865c3a, 0x8fc0a41a, 0x87435536, 0x99eda6f2, + 0x41874794, 0x29cff4e8, 0xb70efd9a, 0x3103f6e7, 0x84d2453b, 0x15a450bd, + 0x74f49af1, 0x60f664b1, 0xa1c86935, 0xfdafbce1, 0xe36353e3, 0x5d9ba739, + 0xbc0559ba, 0x708b0054, 0xd41d808c, 0xb2f31723, 0x9027c41f, 0xf136d165, + 0xb5374b12, 0x9420a6ac, 0x273958b6, 0xe6c2fad0, 0xebdc1f21, 0xfb33af8b, + 0xc71c25cd, 0xe9a2d8e5, 0xbeb38a50, 0xbceb7cc2, 0x4e4e73f0, 0xcd6c251d, + 0xde4c032c, 0x4b04ac30, 0x725b8b21, 0x4eb8c33b, 0x20d07b75, 0x0567aa63, + 0xb56b2bb7, 0xc1f5fd3a, 0xcafd35ca, 0x470dd4da, 0xfe4f94cd, 0xfb8de424, + 0xe8dbcf40, 0xfe50a37a, 0x62db5b5d, 0xf32f4ab6, 0x2c4a8a51, 0x18473dc0, + 0xfe0cbb6e, 0xfe399efd, 0xdf34ecc9, 0x6ccd5055, 0x46097073, 0x139135c2, + 0x721c76f6, 0x1c6a94b4, 0x6eee014d, 0x8a508e02, 0x3da538f5, 0x280d394f, + 0x5248a0c4, 0x3ce94c6c, 0x9a71ad3a, 0x8493dd05, 0xe43f0ab6, 0x18e4ed42, + 0x6c5c0e09, 0x42b06ec9, 0x8d330343, 0xa45b6f59, 0x2a573c0c, 0xd7fd3de6, + 0xeedeab68, 0x5c84dafc, 0xbbd1b1a8, 0xa3ce1ad1, 0x85b70bed, 0xb6add07f, + 0xa531309c, 0x8f8ab852, 0x564de332, 0xeac9ed0c, 0x73da402c, 0x3ec52761, + 0x43af2f4d, 0xd6ff45c8, 0x4c367462, 0xd553bd6a, 0x44724855, 0x3b2aa728, + 0x56e5eb65, 0xeaf16173, 0x33fa42ff, 0xd714bb5d, 0xfbd0a3b9, 0xaf517134, + 0x9416c8cd, 0x534cf94f, 0x548947c2, 0x34193569, 0x32f4389a, 0xfe7028bc, + 0xed73b1ed, 0x9db95770, 0x468e3922, 0x0440c3cd, 0x60059a62, 0x33504562, + 0x2b229fbd, 0x5174dca5, 0xf7028752, 0xd63c6aa8, 0x31276f38, 0x0646721c, + 0xb0191da8, 0xe00e6de0, 0x9eac1a6e, 0x9f7628a5, 0xed6c06ea, 0x0bb8af15, + 0xf119fb12, 0x38693c1c, 0x732bc0fe, 0x84953275, 0xb82ec888, 0x33a4f1b3, + 0x3099835e, 0x028a8782, 0x5fdd51d7, 0xc6c717b3, 0xb06caf71, 0x17c8c111, + 0x61bad754, 0x9fd03061, 0xe09df1af, 0x3bc9eb73, 0x85878413, 0x9889aaf2, + 0x3f5a9e46, 0x42c9f01f, 0x9984a4f4, 0xd5de43cc, 0xd294daed, 0xbecba2d2, + 0xf1f6e72c, 0x5551128a, 0x83af87e2, 0x6f0342ba, }; static uint64_t -hash(unsigned char *p, int n) +hashblk(const unsigned char *p, off_t n) { unsigned char buf[SHA1_DIGEST_LENGTH]; uint64_t h; - SHA1Data(p, n, buf); + SHA1_CTX ctx; + SHA1Init(&ctx); + SHA1Update(&ctx, p, n); + SHA1Final(buf, &ctx); memcpy(&h, buf, sizeof(h)); return be64toh(h); } static const struct got_error * -addblk(struct Dtab *dt, void *buf, int len, int off, uint64_t h) +addblk(struct got_delta_table *dt, FILE *f, off_t len, off_t offset, uint64_t h) { - int i, sz, probe; - struct Dblock *db; + const struct got_error *err = NULL; + int i, nalloc; + uint8_t buf[GOT_DELTIFY_MAXCHUNK]; + size_t r = 0; - probe = h % dt->sz; - while (dt->b[probe].buf != NULL) { - if (len == dt->b[probe].len && - memcmp(buf, dt->b[probe].buf, len) == 0) - return NULL; - probe = (probe + 1) % dt->sz; + if (len == 0) + return NULL; + + i = h % dt->nalloc; + while (dt->blocks[i].len != 0) { + if (r == 0) { + if (fseeko(f, offset, SEEK_SET) == -1) + return got_error_from_errno("fseeko"); + r = fread(buf, 1, len, f); + if (r != len) { + if (ferror(f)) + return got_ferror(f, GOT_ERR_IO); + return NULL; + } + } + /* + * Avoid adding duplicate blocks. + * NB: A matching hash is insufficient for detecting equality. + * The hash can only detect inequality, so only check 'len'. + */ + if (len == dt->blocks[i].len) { + uint8_t buf2[GOT_DELTIFY_MAXCHUNK]; + if (fseeko(f, dt->blocks[i].offset, SEEK_SET) == -1) + return got_error_from_errno("fseeko"); + if (fread(buf2, 1, len, f) != len) + return got_ferror(f, GOT_ERR_IO); + if (memcmp(buf, buf2, len) == 0) + return NULL; + } + + i = (i + 1) % dt->nalloc; } - assert(dt->b[probe].buf == NULL); - dt->b[probe].buf = buf; - dt->b[probe].len = len; - dt->b[probe].off = off; - dt->b[probe].hash = h; - dt->nb++; - if (dt->sz < 2 * dt->nb) { - sz = dt->sz; - db = dt->b; - dt->sz *= 2; - dt->nb = 0; - dt->b = calloc(dt->sz, sizeof(struct Dblock)); - if (dt->b == NULL) - return got_error_from_errno("calloc"); - for (i = 0; i < sz; i++) { - if (db[i].buf != NULL) - return addblk(dt, db[i].buf, db[i].len, - db[i].off, db[i].hash); + assert(dt->blocks[i].len == 0); + dt->blocks[i].len = len; + dt->blocks[i].offset = offset; + dt->blocks[i].hash = h; + dt->nblocks++; + if (dt->nalloc < 2 * dt->nblocks) { + struct got_delta_block *db; + nalloc = dt->nalloc * 2; + db = dt->blocks; + dt->blocks = calloc(nalloc, sizeof(struct got_delta_block)); + if (dt->blocks == NULL) { + err = got_error_from_errno("calloc"); + dt->blocks = db; + return err; } + dt->nalloc = nalloc; + /* + * Recompute all block positions. Hash-based indices of blocks + * in the array depend on the allocated length of the array. + */ + dt->nblocks = 0; + for (i = 0; i < nalloc; i++) { + if (db[i].len == 0) + continue; + err = addblk(dt, f, db[i].len, db[i].offset, + db[i].hash); + if (err) + break; + } free(db); } - return NULL; + return err; } -static struct Dblock * -lookup(struct Dtab *dt, unsigned char *p, int n) +static const struct got_error * +lookupblk(struct got_delta_block **block, struct got_delta_table *dt, + unsigned char *p, off_t len, FILE *basefile) { - int probe; + int i; uint64_t h; + uint8_t buf[GOT_DELTIFY_MAXCHUNK]; + size_t r; - h = hash(p, n); - for (probe = h % dt->sz; dt->b[probe].buf != NULL; - probe = (probe + 1) % dt->sz) { - if (dt->b[probe].hash != h) + *block = NULL; + + h = hashblk(p, len); + for (i = h % dt->nalloc; dt->blocks[i].len != 0; + i = (i + 1) % dt->nalloc) { + if (dt->blocks[i].hash != h || + dt->blocks[i].len != len) continue; - if (n != dt->b[probe].len) - continue; - if (memcmp(p, dt->b[probe].buf, n) != 0) - continue; - return &dt->b[probe]; + if (fseeko(basefile, dt->blocks[i].offset, SEEK_SET) == -1) + return got_error_from_errno("fseeko"); + r = fread(buf, 1, len, basefile); + if (r != len) + return got_ferror(basefile, GOT_ERR_IO); + if (memcmp(p, buf, len) == 0) { + *block = &dt->blocks[i]; + break; + } } return NULL; } -static int -nextblk(unsigned char *s, unsigned char *e) +static const struct got_error * +nextblk(uint8_t *buf, off_t *blocklen, FILE *f) { uint32_t gh; - unsigned char *p; + const unsigned char *p; + size_t r; + off_t pos = ftello(f); - if ((e - s) < Minchunk) - return e - s; - p = s + Minchunk; - if ((e - s) > Maxchunk) - e = s + Maxchunk; - gh = 0; - while (p != e) { + *blocklen = 0; + + r = fread(buf, 1, GOT_DELTIFY_MAXCHUNK, f); + if (r == 0 && ferror(f)) + return got_ferror(f, GOT_ERR_IO); + if (r < GOT_DELTIFY_MINCHUNK) + return NULL; /* no more delta-worthy blocks left */ + + /* Got a deltifiable block. Find the split-point where it ends. */ + p = buf + GOT_DELTIFY_MINCHUNK; + gh = 0; + while (p != buf + r) { gh = (gh << 1) + geartab[*p++]; - if ((gh & Splitmask) == 0) + if ((gh & GOT_DELTIFY_SPLITMASK) == 0) break; } - return p - s; + + *blocklen = (p - buf); + if (fseeko(f, pos + *blocklen, SEEK_SET) == -1) + return got_error_from_errno("fseeko"); + + return NULL; } const struct got_error * -dtinit(struct Dtab *dt, struct got_object *obj) +got_deltify_init(struct got_delta_table **dt, FILE *f, off_t fileoffset, + off_t filesize) { - unsigned char *s = NULL, *e; + const struct got_error *err = NULL; uint64_t h; - long n, o; - - o = 0; -#ifdef notyet - s = (unsigned char *)obj->data; -#endif - e = s + obj->size; - dt->nb = 0; - dt->sz = 128; - dt->b = calloc(dt->sz, sizeof(struct Dblock)); - if (dt->b == NULL) + + *dt = calloc(1, sizeof(**dt)); + if (*dt == NULL) return got_error_from_errno("calloc"); -#ifdef notyet - dt->base = (unsigned char *)obj->data; -#endif - dt->nbase = obj->size; - while (s != e) { - n = nextblk(s, e); - h = hash(s, n); - addblk(dt, s, n, o, h); - s += n; - o += n; + + (*dt)->nblocks = 0; + (*dt)->nalloc = 128; + (*dt)->blocks = calloc((*dt)->nalloc, sizeof(struct got_delta_block)); + if ((*dt)->blocks == NULL) { + err = got_error_from_errno("calloc"); + goto done; } - return NULL; + if (fseeko(f, fileoffset, SEEK_SET) == -1) + return got_error_from_errno("fseeko"); + + while (fileoffset < filesize) { + uint8_t buf[GOT_DELTIFY_MAXCHUNK]; + off_t blocklen; + err = nextblk(buf, &blocklen, f); + if (err) + goto done; + if (blocklen == 0) + break; + h = hashblk(buf, blocklen); + err = addblk(*dt, f, blocklen, fileoffset, h); + if (err) + goto done; + fileoffset += blocklen; + } +done: + if (err) { + free((*dt)->blocks); + free(*dt); + *dt = NULL; + } + + return err; } void -dtclear(struct Dtab *dt) +got_deltify_free(struct got_delta_table *dt) { - free(dt->b); + free(dt->blocks); + free(dt); } static const struct got_error * -emitdelta(struct Delta **pd, int *nd, int cpy, int off, int len) +emitdelta(struct got_delta_instruction **deltas, int *ndeltas, int copy, + off_t offset, off_t len) { - struct Delta *d, *p; + struct got_delta_instruction *d, *p; - *nd += 1; - p = reallocarray(*pd, *nd, sizeof(struct Delta)); + *ndeltas += 1; + p = reallocarray(*deltas, *ndeltas, + sizeof(struct got_delta_instruction)); if (p == NULL) return got_error_from_errno("realloc"); - *pd = p; - d = &(*pd)[*nd - 1]; - d->cpy = cpy; - d->off = off; + *deltas = p; + d = &(*deltas)[*ndeltas - 1]; + d->copy = copy; + d->offset = offset; d->len = len; return NULL; } -static int -stretch(struct Dtab *dt, struct Dblock *b, unsigned char *s, - unsigned char *e, int n) +static const struct got_error * +stretchblk(FILE *basefile, struct got_delta_block *block, FILE *f, + off_t filesize, off_t *blocklen) { - unsigned char *p, *q, *eb; + uint8_t basebuf[GOT_DELTIFY_MAXCHUNK], buf[GOT_DELTIFY_MAXCHUNK]; + size_t base_r, r, i; + off_t orig_blocklen = *blocklen; + off_t pos = ftello(f); + int buf_equal = 1; - if (b == NULL) - return n; - p = s + n; - q = dt->base + b->off + n; - eb = dt->base + dt->nbase; - while (n < (1 << 24) - 1) { - if (p == e || q == eb) + if (fseeko(basefile, block->offset, SEEK_SET) == -1) + return got_error_from_errno("fseeko"); + + while (buf_equal && *blocklen < (1 << 24) - 1) { + base_r = fread(basebuf, 1, sizeof(basebuf), basefile); + if (base_r == 0) { + if (ferror(basefile)) + return got_ferror(basefile, GOT_ERR_IO); break; - if (*p != *q) + } + r = fread(buf, 1, sizeof(buf), f); + if (r == 0) { + if (ferror(f)) + return got_ferror(f, GOT_ERR_IO); break; - p++; - q++; - n++; + } + for (i = 0; i < MIN(base_r, r); i++) { + if (buf[i] != basebuf[i]) { + buf_equal = 0; + break; + } + (*blocklen)++; + } } - return n; + + if (fseeko(f, pos + *blocklen - orig_blocklen, SEEK_SET) == -1) + return got_error_from_errno("fseeko"); + + return NULL; } -struct Delta * -deltify(struct got_object *obj, struct Dtab *dt, int *pnd) +const struct got_error * +got_deltify(struct got_delta_instruction **deltas, int *ndeltas, + FILE *f, off_t fileoffset, off_t filesize, + struct got_delta_table *dt, FILE *basefile, + off_t basefile_size) { - struct Delta *d; - struct Dblock *b; - unsigned char *s = NULL, *e; - long n, o; - - o = 0; - d = NULL; -#ifdef notyet - s = (unsigned char *)obj->data; -#endif - e = s + obj->size; - *pnd = 0; - while (s != e) { - n = nextblk(s, e); - b = lookup(dt, s, n); - n = stretch(dt, b, s, e, n); - if (b != NULL) - emitdelta(&d, pnd, 1, b->off, n); - else - emitdelta(&d, pnd, 0, o, n); - s += n; - o += n; + const struct got_error *err = NULL; + const off_t offset0 = fileoffset; + + *deltas = NULL; + *ndeltas = 0; + + /* + * offset0 indicates where data to be deltified begins. + * For example, we want to avoid deltifying a Git object header at + * the beginning of the file. + */ + if (fseeko(f, offset0, SEEK_SET) == -1) + return got_error_from_errno("fseeko"); + + while (fileoffset < filesize) { + uint8_t buf[GOT_DELTIFY_MAXCHUNK]; + off_t blocklen; + struct got_delta_block *block; + err = nextblk(buf, &blocklen, f); + if (err) + break; + if (blocklen == 0) + break; + err = lookupblk(&block, dt, buf, blocklen, basefile); + if (err) + break; + if (block != NULL) { + /* + * We have found a matching block in the delta base. + * Attempt to stretch the block as far as possible and + * generate a copy instruction. + */ + err = stretchblk(basefile, block, f, filesize, + &blocklen); + if (err) + break; + emitdelta(deltas, ndeltas, 1, block->offset, blocklen); + } else { + /* + * No match. + * This block needs to be sourced from the file itself. + */ + emitdelta(deltas, ndeltas, 0, fileoffset - offset0, + blocklen); + } + fileoffset += blocklen; } - return d; + + if (err) { + free(*deltas); + *deltas = NULL; + *ndeltas = 0; + } + return err; } blob - /dev/null blob + 39069a604eca508347a2f734e6fe70185a3febea (mode 644) --- /dev/null +++ lib/got_lib_deltify.h @@ -0,0 +1,48 @@ +/* + * Copyright (c) 2020 Ori Bernstein + * Copyright (c) 2021 Stefan Sperling + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +struct got_delta_block { + off_t len; + off_t offset; + uint64_t hash; +}; + +struct got_delta_table { + struct got_delta_block *blocks; + int nblocks; + int nalloc; +}; + +struct got_delta_instruction { + int copy; + off_t offset; + off_t len; +}; + +enum { + GOT_DELTIFY_MINCHUNK = 128, + GOT_DELTIFY_MAXCHUNK = 8192, + GOT_DELTIFY_SPLITMASK = (1 << 8) - 1, + +}; + +const struct got_error *got_deltify_init(struct got_delta_table **dt, FILE *f, + off_t fileoffset, off_t filesize); +const struct got_error *got_deltify(struct got_delta_instruction **deltas, + int *ndeltas, FILE *f, off_t fileoffset, off_t filesize, + struct got_delta_table *dt, FILE *basefile, off_t basefile_size); +void got_deltify_free(struct got_delta_table *dt);