+++ /dev/null
-/*
- * Copyright (C) the libgit2 contributors. All rights reserved.
- *
- * This file is part of libgit2, distributed under the GNU GPL v2 with
- * a Linking Exception. For full terms see the included COPYING file.
- */
-
-#include "common.h"
-
-#include "git2/sys/hashsig.h"
-#include "futils.h"
-#include "util.h"
-
-typedef uint32_t hashsig_t;
-typedef uint64_t hashsig_state;
-
-#define HASHSIG_SCALE 100
-
-#define HASHSIG_MAX_RUN 80
-#define HASHSIG_HASH_START INT64_C(0x012345678ABCDEF0)
-#define HASHSIG_HASH_SHIFT 5
-
-#define HASHSIG_HASH_MIX(S,CH) \
- (S) = ((S) << HASHSIG_HASH_SHIFT) - (S) + (hashsig_state)(CH)
-
-#define HASHSIG_HEAP_SIZE ((1 << 7) - 1)
-#define HASHSIG_HEAP_MIN_SIZE 4
-
-typedef int (*hashsig_cmp)(const void *a, const void *b, void *);
-
-typedef struct {
- int size, asize;
- hashsig_cmp cmp;
- hashsig_t values[HASHSIG_HEAP_SIZE];
-} hashsig_heap;
-
-struct git_hashsig {
- hashsig_heap mins;
- hashsig_heap maxs;
- size_t lines;
- git_hashsig_option_t opt;
-};
-
-#define HEAP_LCHILD_OF(I) (((I)<<1)+1)
-#define HEAP_RCHILD_OF(I) (((I)<<1)+2)
-#define HEAP_PARENT_OF(I) (((I)-1)>>1)
-
-static void hashsig_heap_init(hashsig_heap *h, hashsig_cmp cmp)
-{
- h->size = 0;
- h->asize = HASHSIG_HEAP_SIZE;
- h->cmp = cmp;
-}
-
-static int hashsig_cmp_max(const void *a, const void *b, void *payload)
-{
- hashsig_t av = *(const hashsig_t *)a, bv = *(const hashsig_t *)b;
- GIT_UNUSED(payload);
- return (av < bv) ? -1 : (av > bv) ? 1 : 0;
-}
-
-static int hashsig_cmp_min(const void *a, const void *b, void *payload)
-{
- hashsig_t av = *(const hashsig_t *)a, bv = *(const hashsig_t *)b;
- GIT_UNUSED(payload);
- return (av > bv) ? -1 : (av < bv) ? 1 : 0;
-}
-
-static void hashsig_heap_up(hashsig_heap *h, int el)
-{
- int parent_el = HEAP_PARENT_OF(el);
-
- while (el > 0 && h->cmp(&h->values[parent_el], &h->values[el], NULL) > 0) {
- hashsig_t t = h->values[el];
- h->values[el] = h->values[parent_el];
- h->values[parent_el] = t;
-
- el = parent_el;
- parent_el = HEAP_PARENT_OF(el);
- }
-}
-
-static void hashsig_heap_down(hashsig_heap *h, int el)
-{
- hashsig_t v, lv, rv;
-
- /* 'el < h->size / 2' tests if el is bottom row of heap */
-
- while (el < h->size / 2) {
- int lel = HEAP_LCHILD_OF(el), rel = HEAP_RCHILD_OF(el), swapel;
-
- v = h->values[el];
- lv = h->values[lel];
- rv = h->values[rel];
-
- if (h->cmp(&v, &lv, NULL) < 0 && h->cmp(&v, &rv, NULL) < 0)
- break;
-
- swapel = (h->cmp(&lv, &rv, NULL) < 0) ? lel : rel;
-
- h->values[el] = h->values[swapel];
- h->values[swapel] = v;
-
- el = swapel;
- }
-}
-
-static void hashsig_heap_sort(hashsig_heap *h)
-{
- /* only need to do this at the end for signature comparison */
- git__qsort_r(h->values, h->size, sizeof(hashsig_t), h->cmp, NULL);
-}
-
-static void hashsig_heap_insert(hashsig_heap *h, hashsig_t val)
-{
- /* if heap is not full, insert new element */
- if (h->size < h->asize) {
- h->values[h->size++] = val;
- hashsig_heap_up(h, h->size - 1);
- }
-
- /* if heap is full, pop top if new element should replace it */
- else if (h->cmp(&val, &h->values[0], NULL) > 0) {
- h->size--;
- h->values[0] = h->values[h->size];
- hashsig_heap_down(h, 0);
- }
-
-}
-
-typedef struct {
- int use_ignores;
- uint8_t ignore_ch[256];
-} hashsig_in_progress;
-
-static int hashsig_in_progress_init(
- hashsig_in_progress *prog, git_hashsig *sig)
-{
- int i;
-
- /* no more than one can be set */
- GIT_ASSERT(!(sig->opt & GIT_HASHSIG_IGNORE_WHITESPACE) ||
- !(sig->opt & GIT_HASHSIG_SMART_WHITESPACE));
-
- if (sig->opt & GIT_HASHSIG_IGNORE_WHITESPACE) {
- for (i = 0; i < 256; ++i)
- prog->ignore_ch[i] = git__isspace_nonlf(i);
- prog->use_ignores = 1;
- } else if (sig->opt & GIT_HASHSIG_SMART_WHITESPACE) {
- for (i = 0; i < 256; ++i)
- prog->ignore_ch[i] = git__isspace(i);
- prog->use_ignores = 1;
- } else {
- memset(prog, 0, sizeof(*prog));
- }
-
- return 0;
-}
-
-static int hashsig_add_hashes(
- git_hashsig *sig,
- const uint8_t *data,
- size_t size,
- hashsig_in_progress *prog)
-{
- const uint8_t *scan = data, *end = data + size;
- hashsig_state state = HASHSIG_HASH_START;
- int use_ignores = prog->use_ignores, len;
- uint8_t ch;
-
- while (scan < end) {
- state = HASHSIG_HASH_START;
-
- for (len = 0; scan < end && len < HASHSIG_MAX_RUN; ) {
- ch = *scan;
-
- if (use_ignores)
- for (; scan < end && git__isspace_nonlf(ch); ch = *scan)
- ++scan;
- else if (sig->opt &
- (GIT_HASHSIG_IGNORE_WHITESPACE | GIT_HASHSIG_SMART_WHITESPACE))
- for (; scan < end && ch == '\r'; ch = *scan)
- ++scan;
-
- /* peek at next character to decide what to do next */
- if (sig->opt & GIT_HASHSIG_SMART_WHITESPACE)
- use_ignores = (ch == '\n');
-
- if (scan >= end)
- break;
- ++scan;
-
- /* check run terminator */
- if (ch == '\n' || ch == '\0') {
- sig->lines++;
- break;
- }
-
- ++len;
- HASHSIG_HASH_MIX(state, ch);
- }
-
- if (len > 0) {
- hashsig_heap_insert(&sig->mins, (hashsig_t)state);
- hashsig_heap_insert(&sig->maxs, (hashsig_t)state);
-
- while (scan < end && (*scan == '\n' || !*scan))
- ++scan;
- }
- }
-
- prog->use_ignores = use_ignores;
-
- return 0;
-}
-
-static int hashsig_finalize_hashes(git_hashsig *sig)
-{
- if (sig->mins.size < HASHSIG_HEAP_MIN_SIZE &&
- !(sig->opt & GIT_HASHSIG_ALLOW_SMALL_FILES)) {
- git_error_set(GIT_ERROR_INVALID,
- "file too small for similarity signature calculation");
- return GIT_EBUFS;
- }
-
- hashsig_heap_sort(&sig->mins);
- hashsig_heap_sort(&sig->maxs);
-
- return 0;
-}
-
-static git_hashsig *hashsig_alloc(git_hashsig_option_t opts)
-{
- git_hashsig *sig = git__calloc(1, sizeof(git_hashsig));
- if (!sig)
- return NULL;
-
- hashsig_heap_init(&sig->mins, hashsig_cmp_min);
- hashsig_heap_init(&sig->maxs, hashsig_cmp_max);
- sig->opt = opts;
-
- return sig;
-}
-
-int git_hashsig_create(
- git_hashsig **out,
- const char *buf,
- size_t buflen,
- git_hashsig_option_t opts)
-{
- int error;
- hashsig_in_progress prog;
- git_hashsig *sig = hashsig_alloc(opts);
- GIT_ERROR_CHECK_ALLOC(sig);
-
- if ((error = hashsig_in_progress_init(&prog, sig)) < 0)
- return error;
-
- error = hashsig_add_hashes(sig, (const uint8_t *)buf, buflen, &prog);
-
- if (!error)
- error = hashsig_finalize_hashes(sig);
-
- if (!error)
- *out = sig;
- else
- git_hashsig_free(sig);
-
- return error;
-}
-
-int git_hashsig_create_fromfile(
- git_hashsig **out,
- const char *path,
- git_hashsig_option_t opts)
-{
- uint8_t buf[0x1000];
- ssize_t buflen = 0;
- int error = 0, fd;
- hashsig_in_progress prog;
- git_hashsig *sig = hashsig_alloc(opts);
- GIT_ERROR_CHECK_ALLOC(sig);
-
- if ((fd = git_futils_open_ro(path)) < 0) {
- git__free(sig);
- return fd;
- }
-
- if ((error = hashsig_in_progress_init(&prog, sig)) < 0) {
- p_close(fd);
- return error;
- }
-
- while (!error) {
- if ((buflen = p_read(fd, buf, sizeof(buf))) <= 0) {
- if ((error = (int)buflen) < 0)
- git_error_set(GIT_ERROR_OS,
- "read error on '%s' calculating similarity hashes", path);
- break;
- }
-
- error = hashsig_add_hashes(sig, buf, buflen, &prog);
- }
-
- p_close(fd);
-
- if (!error)
- error = hashsig_finalize_hashes(sig);
-
- if (!error)
- *out = sig;
- else
- git_hashsig_free(sig);
-
- return error;
-}
-
-void git_hashsig_free(git_hashsig *sig)
-{
- git__free(sig);
-}
-
-static int hashsig_heap_compare(const hashsig_heap *a, const hashsig_heap *b)
-{
- int matches = 0, i, j, cmp;
-
- GIT_ASSERT_WITH_RETVAL(a->cmp == b->cmp, 0);
-
- /* hash heaps are sorted - just look for overlap vs total */
-
- for (i = 0, j = 0; i < a->size && j < b->size; ) {
- cmp = a->cmp(&a->values[i], &b->values[j], NULL);
-
- if (cmp < 0)
- ++i;
- else if (cmp > 0)
- ++j;
- else {
- ++i; ++j; ++matches;
- }
- }
-
- return HASHSIG_SCALE * (matches * 2) / (a->size + b->size);
-}
-
-int git_hashsig_compare(const git_hashsig *a, const git_hashsig *b)
-{
- /* if we have no elements in either file then each file is either
- * empty or blank. if we're ignoring whitespace then the files are
- * similar, otherwise they're dissimilar.
- */
- if (a->mins.size == 0 && b->mins.size == 0) {
- if ((!a->lines && !b->lines) ||
- (a->opt & GIT_HASHSIG_IGNORE_WHITESPACE))
- return HASHSIG_SCALE;
- else
- return 0;
- }
-
- /* if we have fewer than the maximum number of elements, then just use
- * one array since the two arrays will be the same
- */
- if (a->mins.size < HASHSIG_HEAP_SIZE) {
- return hashsig_heap_compare(&a->mins, &b->mins);
- } else {
- int mins, maxs;
-
- if ((mins = hashsig_heap_compare(&a->mins, &b->mins)) < 0)
- return mins;
- if ((maxs = hashsig_heap_compare(&a->maxs, &b->maxs)) < 0)
- return maxs;
-
- return (mins + maxs) / 2;
- }
-}
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