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![Junio C Hamano](/assets/img/avatar_default.png)
Usually we do not pass an empty string to the function hash_name() because we almost always ask for hash values for a path that is a candidate to be added to the index. However, check-ignore (and most likely check-attr, but I didn't check) apparently has a callchain to ask the hash value for an empty path when it was given a "." from the top-level directory to ask "Is the path . excluded by default?" Make sure that hash_name() does not overrun the end of the given pathname even when it is empty. Remove a sweep-the-issue-under-the-rug conditional in check-ignore that avoided to pass an empty string to the callchain while at it. It is a valid question to ask for check-ignore if the top-level is set to be ignored by default, even though the answer is most likely no, if only because there is currently no way to specify such an entry in the .gitignore file. But it is an unusual thing to ask and it is not worth optimizing for it by special casing at the top level of the call chain. Signed-off-by: Adam Spiers <git@adamspiers.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
191 lines
4.7 KiB
C
191 lines
4.7 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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static void hash_index_entry_directories(struct index_state *istate, struct cache_entry *ce)
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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 the cache.
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*
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* Note that the cache_entry stored with the directory does not
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* represent the directory itself. It is a pointer to an existing
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* filename, and its only purpose is to represent existence of the
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* directory in the cache. It is very possible multiple directory
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* hash entries may point to the same cache_entry.
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*/
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unsigned int hash;
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void **pos;
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const char *ptr = ce->name;
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while (*ptr) {
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while (*ptr && *ptr != '/')
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++ptr;
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if (*ptr == '/') {
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++ptr;
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hash = hash_name(ce->name, ptr - ce->name);
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pos = insert_hash(hash, ce, &istate->name_hash);
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if (pos) {
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ce->dir_next = *pos;
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*pos = ce;
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}
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}
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}
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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 = ce->dir_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)
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hash_index_entry_directories(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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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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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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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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/*
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* If the entry we're comparing is a filename (no trailing slash), then compare
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* the lengths exactly.
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*/
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if (name[namelen - 1] != '/')
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return slow_same_name(name, namelen, ce->name, len);
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/*
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* For a directory, we point to an arbitrary cache_entry filename. Just
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* make sure the directory portion matches.
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*/
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return slow_same_name(name, namelen, ce->name, namelen < len ? namelen : 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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if (icase && name[namelen - 1] == '/')
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ce = ce->dir_next;
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else
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ce = ce->next;
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}
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/*
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* Might be a submodule. 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 the name hash
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* 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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* 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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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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