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tag: v1.7.11
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/*
* name-hash.c
*
* Hashing names in the index state
*
* Copyright (C) 2008 Linus Torvalds
*/
#define NO_THE_INDEX_COMPATIBILITY_MACROS
#include "cache.h"

/*
* This removes bit 5 if bit 6 is set.
*
* That will make US-ASCII characters hash to their upper-case
* equivalent. We could easily do this one whole word at a time,
* but that's for future worries.
*/
static inline unsigned char icase_hash(unsigned char c)
{
return c & ~((c & 0x40) >> 1);
}

static unsigned int hash_name(const char *name, int namelen)
{
unsigned int hash = 0x123;

do {
unsigned char c = *name++;
c = icase_hash(c);
hash = hash*101 + c;
} while (--namelen);
return hash;
}

static void hash_index_entry_directories(struct index_state *istate, struct cache_entry *ce)
{
/*
* Throw each directory component in the hash for quick lookup
* during a git status. Directory components are stored with their
* closing slash. Despite submodules being a directory, they never
* reach this point, because they are stored without a closing slash
* in the cache.
*
* Note that the cache_entry stored with the directory does not
* represent the directory itself. It is a pointer to an existing
* filename, and its only purpose is to represent existence of the
* directory in the cache. It is very possible multiple directory
* hash entries may point to the same cache_entry.
*/
unsigned int hash;
void **pos;

const char *ptr = ce->name;
while (*ptr) {
while (*ptr && *ptr != '/')
++ptr;
if (*ptr == '/') {
++ptr;
hash = hash_name(ce->name, ptr - ce->name);
pos = insert_hash(hash, ce, &istate->name_hash);
if (pos) {
ce->dir_next = *pos;
*pos = ce;
}
}
}
}

static void hash_index_entry(struct index_state *istate, struct cache_entry *ce)
{
void **pos;
unsigned int hash;

if (ce->ce_flags & CE_HASHED)
return;
ce->ce_flags |= CE_HASHED;
ce->next = ce->dir_next = NULL;
hash = hash_name(ce->name, ce_namelen(ce));
pos = insert_hash(hash, ce, &istate->name_hash);
if (pos) {
ce->next = *pos;
*pos = ce;
}

if (ignore_case)
hash_index_entry_directories(istate, ce);
}

static void lazy_init_name_hash(struct index_state *istate)
{
int nr;

if (istate->name_hash_initialized)
return;
for (nr = 0; nr < istate->cache_nr; nr++)
hash_index_entry(istate, istate->cache[nr]);
istate->name_hash_initialized = 1;
}

void add_name_hash(struct index_state *istate, struct cache_entry *ce)
{
ce->ce_flags &= ~CE_UNHASHED;
if (istate->name_hash_initialized)
hash_index_entry(istate, ce);
}

static int slow_same_name(const char *name1, int len1, const char *name2, int len2)
{
if (len1 != len2)
return 0;

while (len1) {
unsigned char c1 = *name1++;
unsigned char c2 = *name2++;
len1--;
if (c1 != c2) {
c1 = toupper(c1);
c2 = toupper(c2);
if (c1 != c2)
return 0;
}
}
return 1;
}

static int same_name(const struct cache_entry *ce, const char *name, int namelen, int icase)
{
int len = ce_namelen(ce);

/*
* Always do exact compare, even if we want a case-ignoring comparison;
* we do the quick exact one first, because it will be the common case.
*/
if (len == namelen && !cache_name_compare(name, namelen, ce->name, len))
return 1;

if (!icase)
return 0;

/*
* If the entry we're comparing is a filename (no trailing slash), then compare
* the lengths exactly.
*/
if (name[namelen - 1] != '/')
return slow_same_name(name, namelen, ce->name, len);

/*
* For a directory, we point to an arbitrary cache_entry filename. Just
* make sure the directory portion matches.
*/
return slow_same_name(name, namelen, ce->name, namelen < len ? namelen : len);
}

struct cache_entry *index_name_exists(struct index_state *istate, const char *name, int namelen, int icase)
{
unsigned int hash = hash_name(name, namelen);
struct cache_entry *ce;

lazy_init_name_hash(istate);
ce = lookup_hash(hash, &istate->name_hash);

while (ce) {
if (!(ce->ce_flags & CE_UNHASHED)) {
if (same_name(ce, name, namelen, icase))
return ce;
}
if (icase && name[namelen - 1] == '/')
ce = ce->dir_next;
else
ce = ce->next;
}

/*
* Might be a submodule. Despite submodules being directories,
* they are stored in the name hash without a closing slash.
* When ignore_case is 1, directories are stored in the name hash
* with their closing slash.
*
* The side effect of this storage technique is we have need to
* remove the slash from name and perform the lookup again without
* the slash. If a match is made, S_ISGITLINK(ce->mode) will be
* true.
*/
if (icase && name[namelen - 1] == '/') {
ce = index_name_exists(istate, name, namelen - 1, icase);
if (ce && S_ISGITLINK(ce->ce_mode))
return ce;
}
return NULL;
}
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