Add case insensitivity support for directories when using git status
[git/git.git] / name-hash.c
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96872bc2
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1/*
2 * name-hash.c
3 *
4 * Hashing names in the index state
5 *
6 * Copyright (C) 2008 Linus Torvalds
7 */
8#define NO_THE_INDEX_COMPATIBILITY_MACROS
9#include "cache.h"
10
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11/*
12 * This removes bit 5 if bit 6 is set.
13 *
14 * That will make US-ASCII characters hash to their upper-case
15 * equivalent. We could easily do this one whole word at a time,
16 * but that's for future worries.
17 */
18static inline unsigned char icase_hash(unsigned char c)
19{
20 return c & ~((c & 0x40) >> 1);
21}
22
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23static unsigned int hash_name(const char *name, int namelen)
24{
25 unsigned int hash = 0x123;
26
27 do {
28 unsigned char c = *name++;
cd2fef59 29 c = icase_hash(c);
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30 hash = hash*101 + c;
31 } while (--namelen);
32 return hash;
33}
34
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35static void hash_index_entry_directories(struct index_state *istate, struct cache_entry *ce)
36{
37 /*
38 * Throw each directory component in the hash for quick lookup
39 * during a git status. Directory components are stored with their
40 * closing slash. Despite submodules being a directory, they never
41 * reach this point, because they are stored without a closing slash
42 * in the cache.
43 *
44 * Note that the cache_entry stored with the directory does not
45 * represent the directory itself. It is a pointer to an existing
46 * filename, and its only purpose is to represent existence of the
47 * directory in the cache. It is very possible multiple directory
48 * hash entries may point to the same cache_entry.
49 */
50 unsigned int hash;
51 void **pos;
52
53 const char *ptr = ce->name;
54 while (*ptr) {
55 while (*ptr && *ptr != '/')
56 ++ptr;
57 if (*ptr == '/') {
58 ++ptr;
59 hash = hash_name(ce->name, ptr - ce->name);
60 if (!lookup_hash(hash, &istate->name_hash)) {
61 pos = insert_hash(hash, ce, &istate->name_hash);
62 if (pos) {
63 ce->next = *pos;
64 *pos = ce;
65 }
66 }
67 }
68 }
69}
70
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71static void hash_index_entry(struct index_state *istate, struct cache_entry *ce)
72{
73 void **pos;
74 unsigned int hash;
75
76 if (ce->ce_flags & CE_HASHED)
77 return;
78 ce->ce_flags |= CE_HASHED;
79 ce->next = NULL;
80 hash = hash_name(ce->name, ce_namelen(ce));
81 pos = insert_hash(hash, ce, &istate->name_hash);
82 if (pos) {
83 ce->next = *pos;
84 *pos = ce;
85 }
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86
87 if (ignore_case)
88 hash_index_entry_directories(istate, ce);
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89}
90
91static void lazy_init_name_hash(struct index_state *istate)
92{
93 int nr;
94
95 if (istate->name_hash_initialized)
96 return;
97 for (nr = 0; nr < istate->cache_nr; nr++)
98 hash_index_entry(istate, istate->cache[nr]);
99 istate->name_hash_initialized = 1;
100}
101
102void add_name_hash(struct index_state *istate, struct cache_entry *ce)
103{
104 ce->ce_flags &= ~CE_UNHASHED;
105 if (istate->name_hash_initialized)
106 hash_index_entry(istate, ce);
107}
108
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109static int slow_same_name(const char *name1, int len1, const char *name2, int len2)
110{
111 if (len1 != len2)
112 return 0;
113
114 while (len1) {
115 unsigned char c1 = *name1++;
116 unsigned char c2 = *name2++;
117 len1--;
118 if (c1 != c2) {
119 c1 = toupper(c1);
120 c2 = toupper(c2);
121 if (c1 != c2)
122 return 0;
123 }
124 }
125 return 1;
126}
127
128static int same_name(const struct cache_entry *ce, const char *name, int namelen, int icase)
129{
130 int len = ce_namelen(ce);
131
132 /*
133 * Always do exact compare, even if we want a case-ignoring comparison;
134 * we do the quick exact one first, because it will be the common case.
135 */
136 if (len == namelen && !cache_name_compare(name, namelen, ce->name, len))
137 return 1;
138
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139 if (!icase)
140 return 0;
141
142 /*
143 * If the entry we're comparing is a filename (no trailing slash), then compare
144 * the lengths exactly.
145 */
146 if (name[namelen - 1] != '/')
147 return slow_same_name(name, namelen, ce->name, len);
148
149 /*
150 * For a directory, we point to an arbitrary cache_entry filename. Just
151 * make sure the directory portion matches.
152 */
153 return slow_same_name(name, namelen, ce->name, namelen < len ? namelen : len);
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154}
155
156struct cache_entry *index_name_exists(struct index_state *istate, const char *name, int namelen, int icase)
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157{
158 unsigned int hash = hash_name(name, namelen);
159 struct cache_entry *ce;
160
161 lazy_init_name_hash(istate);
162 ce = lookup_hash(hash, &istate->name_hash);
163
164 while (ce) {
165 if (!(ce->ce_flags & CE_UNHASHED)) {
cd2fef59 166 if (same_name(ce, name, namelen, icase))
df292c79 167 return ce;
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168 }
169 ce = ce->next;
170 }
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171
172 /*
173 * Might be a submodule. Despite submodules being directories,
174 * they are stored in the name hash without a closing slash.
175 * When ignore_case is 1, directories are stored in the name hash
176 * with their closing slash.
177 *
178 * The side effect of this storage technique is we have need to
179 * remove the slash from name and perform the lookup again without
180 * the slash. If a match is made, S_ISGITLINK(ce->mode) will be
181 * true.
182 */
183 if (icase && name[namelen - 1] == '/') {
184 ce = index_name_exists(istate, name, namelen - 1, icase);
185 if (ce && S_ISGITLINK(ce->ce_mode))
186 return ce;
187 }
df292c79 188 return NULL;
96872bc2 189}