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92e0d91632
* maint-1.8.1: Start preparing for 1.8.1.6 git-tag(1): we tag HEAD by default Fix revision walk for commits with the same dates t2003: work around path mangling issue on Windows pack-refs: add fully-peeled trait pack-refs: write peeled entry for non-tags use parse_object_or_die instead of die("bad object") avoid segfaults on parse_object failure entry: fix filter lookup t2003: modernize style name-hash.c: fix endless loop with core.ignorecase=true
289 lines
7.6 KiB
C
289 lines
7.6 KiB
C
/*
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* name-hash.c
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*
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* Hashing names in the index state
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*
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* Copyright (C) 2008 Linus Torvalds
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*/
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#define NO_THE_INDEX_COMPATIBILITY_MACROS
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#include "cache.h"
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/*
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* This removes bit 5 if bit 6 is set.
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*
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* That will make US-ASCII characters hash to their upper-case
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* equivalent. We could easily do this one whole word at a time,
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* but that's for future worries.
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*/
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static inline unsigned char icase_hash(unsigned char c)
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{
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return c & ~((c & 0x40) >> 1);
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}
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static unsigned int hash_name(const char *name, int namelen)
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{
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unsigned int hash = 0x123;
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while (namelen--) {
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unsigned char c = *name++;
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c = icase_hash(c);
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hash = hash*101 + c;
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}
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return hash;
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}
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struct dir_entry {
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struct dir_entry *next;
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struct dir_entry *parent;
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struct cache_entry *ce;
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int nr;
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unsigned int namelen;
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};
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static struct dir_entry *find_dir_entry(struct index_state *istate,
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const char *name, unsigned int namelen)
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{
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unsigned int hash = hash_name(name, namelen);
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struct dir_entry *dir;
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for (dir = lookup_hash(hash, &istate->dir_hash); dir; dir = dir->next)
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if (dir->namelen == namelen &&
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!strncasecmp(dir->ce->name, name, namelen))
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return dir;
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return NULL;
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}
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static struct dir_entry *hash_dir_entry(struct index_state *istate,
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struct cache_entry *ce, int namelen)
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{
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/*
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* Throw each directory component in the hash for quick lookup
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* during a git status. Directory components are stored with their
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* closing slash. Despite submodules being a directory, they never
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* reach this point, because they are stored without a closing slash
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* in index_state.name_hash (as ordinary cache_entries).
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*
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* Note that the cache_entry stored with the dir_entry merely
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* supplies the name of the directory (up to dir_entry.namelen). We
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* track the number of 'active' files in a directory in dir_entry.nr,
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* so we can tell if the directory is still relevant, e.g. for git
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* status. However, if cache_entries are removed, we cannot pinpoint
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* an exact cache_entry that's still active. It is very possible that
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* multiple dir_entries point to the same cache_entry.
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*/
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struct dir_entry *dir;
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/* get length of parent directory */
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while (namelen > 0 && !is_dir_sep(ce->name[namelen - 1]))
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namelen--;
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if (namelen <= 0)
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return NULL;
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/* lookup existing entry for that directory */
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dir = find_dir_entry(istate, ce->name, namelen);
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if (!dir) {
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/* not found, create it and add to hash table */
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void **pdir;
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unsigned int hash = hash_name(ce->name, namelen);
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dir = xcalloc(1, sizeof(struct dir_entry));
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dir->namelen = namelen;
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dir->ce = ce;
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pdir = insert_hash(hash, dir, &istate->dir_hash);
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if (pdir) {
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dir->next = *pdir;
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*pdir = dir;
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}
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/* recursively add missing parent directories */
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dir->parent = hash_dir_entry(istate, ce, namelen - 1);
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}
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return dir;
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}
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static void add_dir_entry(struct index_state *istate, struct cache_entry *ce)
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{
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/* Add reference to the directory entry (and parents if 0). */
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struct dir_entry *dir = hash_dir_entry(istate, ce, ce_namelen(ce));
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while (dir && !(dir->nr++))
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dir = dir->parent;
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}
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static void remove_dir_entry(struct index_state *istate, struct cache_entry *ce)
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{
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/*
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* Release reference to the directory entry (and parents if 0).
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*
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* Note: we do not remove / free the entry because there's no
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* hash.[ch]::remove_hash and dir->next may point to other entries
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* that are still valid, so we must not free the memory.
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*/
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struct dir_entry *dir = hash_dir_entry(istate, ce, ce_namelen(ce));
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while (dir && dir->nr && !(--dir->nr))
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dir = dir->parent;
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}
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static void hash_index_entry(struct index_state *istate, struct cache_entry *ce)
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{
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void **pos;
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unsigned int hash;
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if (ce->ce_flags & CE_HASHED)
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return;
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ce->ce_flags |= CE_HASHED;
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ce->next = NULL;
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hash = hash_name(ce->name, ce_namelen(ce));
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pos = insert_hash(hash, ce, &istate->name_hash);
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if (pos) {
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ce->next = *pos;
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*pos = ce;
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}
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if (ignore_case && !(ce->ce_flags & CE_UNHASHED))
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add_dir_entry(istate, ce);
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}
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static void lazy_init_name_hash(struct index_state *istate)
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{
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int nr;
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if (istate->name_hash_initialized)
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return;
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if (istate->cache_nr)
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preallocate_hash(&istate->name_hash, istate->cache_nr);
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for (nr = 0; nr < istate->cache_nr; nr++)
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hash_index_entry(istate, istate->cache[nr]);
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istate->name_hash_initialized = 1;
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}
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void add_name_hash(struct index_state *istate, struct cache_entry *ce)
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{
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/* if already hashed, add reference to directory entries */
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if (ignore_case && (ce->ce_flags & CE_STATE_MASK) == CE_STATE_MASK)
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add_dir_entry(istate, ce);
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ce->ce_flags &= ~CE_UNHASHED;
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if (istate->name_hash_initialized)
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hash_index_entry(istate, ce);
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}
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/*
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* We don't actually *remove* it, we can just mark it invalid so that
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* we won't find it in lookups.
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*
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* Not only would we have to search the lists (simple enough), but
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* we'd also have to rehash other hash buckets in case this makes the
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* hash bucket empty (common). So it's much better to just mark
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* it.
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*/
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void remove_name_hash(struct index_state *istate, struct cache_entry *ce)
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{
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/* if already hashed, release reference to directory entries */
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if (ignore_case && (ce->ce_flags & CE_STATE_MASK) == CE_HASHED)
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remove_dir_entry(istate, ce);
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ce->ce_flags |= CE_UNHASHED;
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}
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static int slow_same_name(const char *name1, int len1, const char *name2, int len2)
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{
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if (len1 != len2)
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return 0;
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while (len1) {
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unsigned char c1 = *name1++;
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unsigned char c2 = *name2++;
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len1--;
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if (c1 != c2) {
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c1 = toupper(c1);
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c2 = toupper(c2);
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if (c1 != c2)
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return 0;
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}
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}
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return 1;
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}
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static int same_name(const struct cache_entry *ce, const char *name, int namelen, int icase)
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{
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int len = ce_namelen(ce);
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/*
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* Always do exact compare, even if we want a case-ignoring comparison;
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* we do the quick exact one first, because it will be the common case.
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*/
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if (len == namelen && !cache_name_compare(name, namelen, ce->name, len))
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return 1;
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if (!icase)
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return 0;
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return slow_same_name(name, namelen, ce->name, len);
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}
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struct cache_entry *index_name_exists(struct index_state *istate, const char *name, int namelen, int icase)
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{
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unsigned int hash = hash_name(name, namelen);
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struct cache_entry *ce;
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lazy_init_name_hash(istate);
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ce = lookup_hash(hash, &istate->name_hash);
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while (ce) {
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if (!(ce->ce_flags & CE_UNHASHED)) {
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if (same_name(ce, name, namelen, icase))
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return ce;
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}
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ce = ce->next;
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}
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/*
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* When looking for a directory (trailing '/'), it might be a
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* submodule or a directory. Despite submodules being directories,
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* they are stored in the name hash without a closing slash.
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* When ignore_case is 1, directories are stored in a separate hash
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* table *with* their closing slash.
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*
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* The side effect of this storage technique is we have need to
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* lookup the directory in a separate hash table, and if not found
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* remove the slash from name and perform the lookup again without
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* the slash. If a match is made, S_ISGITLINK(ce->mode) will be
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* true.
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*/
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if (icase && name[namelen - 1] == '/') {
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struct dir_entry *dir = find_dir_entry(istate, name, namelen);
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if (dir && dir->nr)
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return dir->ce;
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ce = index_name_exists(istate, name, namelen - 1, icase);
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if (ce && S_ISGITLINK(ce->ce_mode))
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return ce;
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}
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return NULL;
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}
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static int free_dir_entry(void *entry, void *unused)
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{
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struct dir_entry *dir = entry;
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while (dir) {
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struct dir_entry *next = dir->next;
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free(dir);
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dir = next;
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}
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return 0;
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}
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void free_name_hash(struct index_state *istate)
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{
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if (!istate->name_hash_initialized)
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return;
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istate->name_hash_initialized = 0;
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if (ignore_case)
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/* free directory entries */
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for_each_hash(&istate->dir_hash, free_dir_entry, NULL);
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free_hash(&istate->name_hash);
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free_hash(&istate->dir_hash);
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}
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