зеркало из https://github.com/microsoft/git.git
293 строки
6.8 KiB
C
293 строки
6.8 KiB
C
/*
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* GIT - The information manager from hell
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*
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* Copyright (C) Linus Torvalds, 2005
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*/
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#include <stdarg.h>
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#include "cache.h"
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struct cache_entry **active_cache = NULL;
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unsigned int active_nr = 0, active_alloc = 0;
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int cache_match_stat(struct cache_entry *ce, struct stat *st)
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{
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unsigned int changed = 0;
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if (ce->ce_mtime.sec != htonl(st->st_mtime))
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changed |= MTIME_CHANGED;
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if (ce->ce_ctime.sec != htonl(st->st_ctime))
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changed |= CTIME_CHANGED;
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#ifdef NSEC
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/*
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* nsec seems unreliable - not all filesystems support it, so
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* as long as it is in the inode cache you get right nsec
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* but after it gets flushed, you get zero nsec.
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*/
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if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec)
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changed |= MTIME_CHANGED;
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if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec)
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changed |= CTIME_CHANGED;
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#endif
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if (ce->ce_uid != htonl(st->st_uid) ||
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ce->ce_gid != htonl(st->st_gid))
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changed |= OWNER_CHANGED;
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/* We consider only the owner x bit to be relevant for "mode changes" */
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if (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))
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changed |= MODE_CHANGED;
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if (ce->ce_dev != htonl(st->st_dev) ||
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ce->ce_ino != htonl(st->st_ino))
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changed |= INODE_CHANGED;
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if (ce->ce_size != htonl(st->st_size))
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changed |= DATA_CHANGED;
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return changed;
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}
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int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
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{
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int len1 = flags1 & CE_NAMEMASK;
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int len2 = flags2 & CE_NAMEMASK;
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int len = len1 < len2 ? len1 : len2;
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int cmp;
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cmp = memcmp(name1, name2, len);
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if (cmp)
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return cmp;
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if (len1 < len2)
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return -1;
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if (len1 > len2)
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return 1;
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if (flags1 < flags2)
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return -1;
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if (flags1 > flags2)
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return 1;
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return 0;
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}
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int cache_name_pos(const char *name, int namelen)
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{
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int first, last;
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first = 0;
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last = active_nr;
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while (last > first) {
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int next = (last + first) >> 1;
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struct cache_entry *ce = active_cache[next];
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int cmp = cache_name_compare(name, namelen, ce->name, htons(ce->ce_flags));
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if (!cmp)
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return next;
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if (cmp < 0) {
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last = next;
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continue;
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}
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first = next+1;
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}
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return -first-1;
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}
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/* Remove entry, return true if there are more entries to go.. */
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static int remove_entry_at(int pos)
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{
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active_nr--;
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if (pos >= active_nr)
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return 0;
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memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
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return 1;
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}
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int remove_file_from_cache(char *path)
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{
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int pos = cache_name_pos(path, strlen(path));
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if (pos < 0)
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pos = -pos-1;
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while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
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remove_entry_at(pos);
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return 0;
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}
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static int same_name(struct cache_entry *a, struct cache_entry *b)
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{
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int len = ce_namelen(a);
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return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
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}
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int add_cache_entry(struct cache_entry *ce, int ok_to_add)
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{
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int pos;
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pos = cache_name_pos(ce->name, htons(ce->ce_flags));
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/* existing match? Just replace it */
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if (pos >= 0) {
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active_cache[pos] = ce;
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return 0;
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}
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pos = -pos-1;
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/*
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* Inserting a merged entry ("stage 0") into the index
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* will always replace all non-merged entries..
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*/
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if (pos < active_nr && ce_stage(ce) == 0) {
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while (same_name(active_cache[pos], ce)) {
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ok_to_add = 1;
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if (!remove_entry_at(pos))
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break;
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}
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}
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if (!ok_to_add)
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return -1;
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/* Make sure the array is big enough .. */
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if (active_nr == active_alloc) {
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active_alloc = alloc_nr(active_alloc);
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active_cache = realloc(active_cache, active_alloc * sizeof(struct cache_entry *));
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}
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/* Add it in.. */
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active_nr++;
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if (active_nr > pos)
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memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
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active_cache[pos] = ce;
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return 0;
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}
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static int verify_hdr(struct cache_header *hdr, unsigned long size)
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{
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SHA_CTX c;
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unsigned char sha1[20];
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if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
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return error("bad signature");
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if (hdr->hdr_version != htonl(2))
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return error("bad index version");
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SHA1_Init(&c);
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SHA1_Update(&c, hdr, size - 20);
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SHA1_Final(sha1, &c);
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if (memcmp(sha1, (void *)hdr + size - 20, 20))
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return error("bad index file sha1 signature");
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return 0;
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}
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int read_cache(void)
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{
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int fd, i;
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struct stat st;
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unsigned long size, offset;
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void *map;
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struct cache_header *hdr;
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errno = EBUSY;
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if (active_cache)
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return error("more than one cachefile");
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errno = ENOENT;
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sha1_file_directory = getenv(DB_ENVIRONMENT);
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if (!sha1_file_directory)
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sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
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if (access(sha1_file_directory, X_OK) < 0)
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return error("no access to SHA1 file directory");
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fd = open(".git/index", O_RDONLY);
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if (fd < 0)
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return (errno == ENOENT) ? 0 : error("open failed");
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size = 0; // avoid gcc warning
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map = (void *)-1;
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if (!fstat(fd, &st)) {
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size = st.st_size;
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errno = EINVAL;
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if (size >= sizeof(struct cache_header) + 20)
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map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
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}
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close(fd);
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if (-1 == (int)(long)map)
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return error("mmap failed");
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hdr = map;
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if (verify_hdr(hdr, size) < 0)
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goto unmap;
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active_nr = ntohl(hdr->hdr_entries);
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active_alloc = alloc_nr(active_nr);
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active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
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offset = sizeof(*hdr);
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for (i = 0; i < active_nr; i++) {
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struct cache_entry *ce = map + offset;
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offset = offset + ce_size(ce);
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active_cache[i] = ce;
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}
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return active_nr;
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unmap:
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munmap(map, size);
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errno = EINVAL;
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return error("verify header failed");
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}
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#define WRITE_BUFFER_SIZE 8192
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static char write_buffer[WRITE_BUFFER_SIZE];
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static unsigned long write_buffer_len;
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static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
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{
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while (len) {
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unsigned int buffered = write_buffer_len;
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unsigned int partial = WRITE_BUFFER_SIZE - buffered;
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if (partial > len)
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partial = len;
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memcpy(write_buffer + buffered, data, partial);
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buffered += partial;
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if (buffered == WRITE_BUFFER_SIZE) {
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SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
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if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
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return -1;
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buffered = 0;
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}
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write_buffer_len = buffered;
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len -= partial;
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data += partial;
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}
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return 0;
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}
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static int ce_flush(SHA_CTX *context, int fd)
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{
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unsigned int left = write_buffer_len;
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if (left) {
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write_buffer_len = 0;
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SHA1_Update(context, write_buffer, left);
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}
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/* Append the SHA1 signature at the end */
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SHA1_Final(write_buffer + left, context);
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left += 20;
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if (write(fd, write_buffer, left) != left)
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return -1;
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return 0;
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}
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int write_cache(int newfd, struct cache_entry **cache, int entries)
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{
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SHA_CTX c;
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struct cache_header hdr;
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int i;
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hdr.hdr_signature = htonl(CACHE_SIGNATURE);
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hdr.hdr_version = htonl(2);
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hdr.hdr_entries = htonl(entries);
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SHA1_Init(&c);
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if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
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return -1;
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for (i = 0; i < entries; i++) {
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struct cache_entry *ce = cache[i];
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if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
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return -1;
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}
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return ce_flush(&c, newfd);
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}
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