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https://github.com/git/git
synced 2024-08-27 11:39:22 +00:00
2cb45e9543
Thomas Glanzmann points out that it doesn't work well with different clients accessing the repository over NFS - they have different views on what the "device" for the filesystem is. Of course, other filesystems may not even have stable inode numbers. But we don't care. At least for now.
458 lines
11 KiB
C
458 lines
11 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 "cache.h"
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struct cache_entry **active_cache = NULL;
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unsigned int active_nr = 0, active_alloc = 0, active_cache_changed = 0;
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/*
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* This only updates the "non-critical" parts of the directory
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* cache, ie the parts that aren't tracked by GIT, and only used
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* to validate the cache.
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*/
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void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
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{
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ce->ce_ctime.sec = htonl(st->st_ctime);
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ce->ce_mtime.sec = htonl(st->st_mtime);
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#ifdef USE_NSEC
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ce->ce_ctime.nsec = htonl(st->st_ctim.tv_nsec);
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ce->ce_mtime.nsec = htonl(st->st_mtim.tv_nsec);
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#endif
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ce->ce_dev = htonl(st->st_dev);
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ce->ce_ino = htonl(st->st_ino);
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ce->ce_uid = htonl(st->st_uid);
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ce->ce_gid = htonl(st->st_gid);
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ce->ce_size = htonl(st->st_size);
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}
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int ce_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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switch (ntohl(ce->ce_mode) & S_IFMT) {
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case S_IFREG:
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changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
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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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break;
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case S_IFLNK:
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changed |= !S_ISLNK(st->st_mode) ? TYPE_CHANGED : 0;
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break;
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default:
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die("internal error: ce_mode is %o", ntohl(ce->ce_mode));
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}
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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 USE_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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if (ce->ce_ino != htonl(st->st_ino))
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changed |= INODE_CHANGED;
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#ifdef USE_STDEV
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/*
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* st_dev breaks on network filesystems where different
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* clients will have different views of what "device"
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* the filesystem is on
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*/
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if (ce->ce_dev != htonl(st->st_dev))
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changed |= INODE_CHANGED;
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#endif
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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 base_name_compare(const char *name1, int len1, int mode1,
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const char *name2, int len2, int mode2)
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{
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unsigned char c1, c2;
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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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c1 = name1[len];
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c2 = name2[len];
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if (!c1 && S_ISDIR(mode1))
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c1 = '/';
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if (!c2 && S_ISDIR(mode2))
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c2 = '/';
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return (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
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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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int remove_cache_entry_at(int pos)
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{
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active_cache_changed = 1;
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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_cache_entry_at(pos);
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return 0;
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}
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int ce_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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/* We may be in a situation where we already have path/file and path
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* is being added, or we already have path and path/file is being
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* added. Either one would result in a nonsense tree that has path
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* twice when git-write-tree tries to write it out. Prevent it.
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*
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* If ok-to-replace is specified, we remove the conflicting entries
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* from the cache so the caller should recompute the insert position.
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* When this happens, we return non-zero.
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*/
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static int check_file_directory_conflict(const struct cache_entry *ce,
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int ok_to_replace)
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{
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int pos, replaced = 0;
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const char *path = ce->name;
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int namelen = strlen(path);
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int stage = ce_stage(ce);
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char *pathbuf = xmalloc(namelen + 1);
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char *cp;
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memcpy(pathbuf, path, namelen + 1);
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/*
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* We are inserting path/file. Do they have path registered at
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* the same stage? We need to do this for all the levels of our
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* subpath.
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*/
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cp = pathbuf;
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while (1) {
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char *ep = strchr(cp, '/');
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if (!ep)
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break;
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*ep = 0; /* first cut it at slash */
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pos = cache_name_pos(pathbuf,
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htons(create_ce_flags(ep-cp, stage)));
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if (0 <= pos) {
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/* Our leading path component is registered as a file,
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* and we are trying to make it a directory. This is
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* bad.
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*/
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if (!ok_to_replace) {
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free(pathbuf);
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return -1;
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}
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fprintf(stderr, "removing file '%s' to replace it with a directory to create '%s'.\n", pathbuf, path);
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remove_cache_entry_at(pos);
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replaced = 1;
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}
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*ep = '/'; /* then restore it and go downwards */
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cp = ep + 1;
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}
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free(pathbuf);
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/* Do we have an entry in the cache that makes our path a prefix
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* of it? That is, are we creating a file where they already expect
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* a directory there?
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*/
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pos = cache_name_pos(path,
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htons(create_ce_flags(namelen, stage)));
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/* (0 <= pos) cannot happen because add_cache_entry()
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* should have taken care of that case.
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*/
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pos = -pos-1;
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/* pos would point at an existing entry that would come immediately
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* after our path. It could be the same as our path in higher stage,
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* or different path but in a lower stage.
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*
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* E.g. when we are inserting path at stage 2,
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*
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* 1 path
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* pos-> 3 path
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* 2 path/file1
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* 3 path/file1
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* 2 path/file2
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* 2 patho
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*
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* We need to examine pos, ignore it because it is at different
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* stage, examine next to find the path/file at stage 2, and
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* complain. We need to do this until we are not the leading
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* path of an existing entry anymore.
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*/
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while (pos < active_nr) {
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struct cache_entry *other = active_cache[pos];
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if (strncmp(other->name, path, namelen))
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break; /* it is not our "subdirectory" anymore */
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if ((ce_stage(other) == stage) &&
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other->name[namelen] == '/') {
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if (!ok_to_replace)
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return -1;
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fprintf(stderr, "removing file '%s' under '%s' to be replaced with a file\n", other->name, path);
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remove_cache_entry_at(pos);
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replaced = 1;
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continue; /* cycle without updating pos */
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}
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pos++;
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}
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return replaced;
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}
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int add_cache_entry(struct cache_entry *ce, int option)
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{
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int pos;
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int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
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int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
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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_changed = 1;
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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 (ce_same_name(active_cache[pos], ce)) {
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ok_to_add = 1;
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if (!remove_cache_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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if (check_file_directory_conflict(ce, ok_to_replace)) {
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if (!ok_to_replace)
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return -1;
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pos = cache_name_pos(ce->name, htons(ce->ce_flags));
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pos = -pos-1;
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}
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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 = xrealloc(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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active_cache_changed = 1;
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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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fd = open(get_index_file(), 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 | PROT_WRITE, 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 unsigned 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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