Merge branch 'jc/fsck-dropped-errors'
[git] / split-index.c
1 #include "cache.h"
2 #include "split-index.h"
3 #include "ewah/ewok.h"
4
5 struct split_index *init_split_index(struct index_state *istate)
6 {
7         if (!istate->split_index) {
8                 istate->split_index = xcalloc(1, sizeof(*istate->split_index));
9                 istate->split_index->refcount = 1;
10         }
11         return istate->split_index;
12 }
13
14 int read_link_extension(struct index_state *istate,
15                          const void *data_, unsigned long sz)
16 {
17         const unsigned char *data = data_;
18         struct split_index *si;
19         int ret;
20
21         if (sz < 20)
22                 return error("corrupt link extension (too short)");
23         si = init_split_index(istate);
24         hashcpy(si->base_sha1, data);
25         data += 20;
26         sz -= 20;
27         if (!sz)
28                 return 0;
29         si->delete_bitmap = ewah_new();
30         ret = ewah_read_mmap(si->delete_bitmap, data, sz);
31         if (ret < 0)
32                 return error("corrupt delete bitmap in link extension");
33         data += ret;
34         sz -= ret;
35         si->replace_bitmap = ewah_new();
36         ret = ewah_read_mmap(si->replace_bitmap, data, sz);
37         if (ret < 0)
38                 return error("corrupt replace bitmap in link extension");
39         if (ret != sz)
40                 return error("garbage at the end of link extension");
41         return 0;
42 }
43
44 int write_link_extension(struct strbuf *sb,
45                          struct index_state *istate)
46 {
47         struct split_index *si = istate->split_index;
48         strbuf_add(sb, si->base_sha1, 20);
49         if (!si->delete_bitmap && !si->replace_bitmap)
50                 return 0;
51         ewah_serialize_strbuf(si->delete_bitmap, sb);
52         ewah_serialize_strbuf(si->replace_bitmap, sb);
53         return 0;
54 }
55
56 static void mark_base_index_entries(struct index_state *base)
57 {
58         int i;
59         /*
60          * To keep track of the shared entries between
61          * istate->base->cache[] and istate->cache[], base entry
62          * position is stored in each base entry. All positions start
63          * from 1 instead of 0, which is resrved to say "this is a new
64          * entry".
65          */
66         for (i = 0; i < base->cache_nr; i++)
67                 base->cache[i]->index = i + 1;
68 }
69
70 void move_cache_to_base_index(struct index_state *istate)
71 {
72         struct split_index *si = istate->split_index;
73         int i;
74
75         /*
76          * do not delete old si->base, its index entries may be shared
77          * with istate->cache[]. Accept a bit of leaking here because
78          * this code is only used by short-lived update-index.
79          */
80         si->base = xcalloc(1, sizeof(*si->base));
81         si->base->version = istate->version;
82         /* zero timestamp disables racy test in ce_write_index() */
83         si->base->timestamp = istate->timestamp;
84         ALLOC_GROW(si->base->cache, istate->cache_nr, si->base->cache_alloc);
85         si->base->cache_nr = istate->cache_nr;
86         memcpy(si->base->cache, istate->cache,
87                sizeof(*istate->cache) * istate->cache_nr);
88         mark_base_index_entries(si->base);
89         for (i = 0; i < si->base->cache_nr; i++)
90                 si->base->cache[i]->ce_flags &= ~CE_UPDATE_IN_BASE;
91 }
92
93 static void mark_entry_for_delete(size_t pos, void *data)
94 {
95         struct index_state *istate = data;
96         if (pos >= istate->cache_nr)
97                 die("position for delete %d exceeds base index size %d",
98                     (int)pos, istate->cache_nr);
99         istate->cache[pos]->ce_flags |= CE_REMOVE;
100         istate->split_index->nr_deletions = 1;
101 }
102
103 static void replace_entry(size_t pos, void *data)
104 {
105         struct index_state *istate = data;
106         struct split_index *si = istate->split_index;
107         struct cache_entry *dst, *src;
108
109         if (pos >= istate->cache_nr)
110                 die("position for replacement %d exceeds base index size %d",
111                     (int)pos, istate->cache_nr);
112         if (si->nr_replacements >= si->saved_cache_nr)
113                 die("too many replacements (%d vs %d)",
114                     si->nr_replacements, si->saved_cache_nr);
115         dst = istate->cache[pos];
116         if (dst->ce_flags & CE_REMOVE)
117                 die("entry %d is marked as both replaced and deleted",
118                     (int)pos);
119         src = si->saved_cache[si->nr_replacements];
120         if (ce_namelen(src))
121                 die("corrupt link extension, entry %d should have "
122                     "zero length name", (int)pos);
123         src->index = pos + 1;
124         src->ce_flags |= CE_UPDATE_IN_BASE;
125         src->ce_namelen = dst->ce_namelen;
126         copy_cache_entry(dst, src);
127         free(src);
128         si->nr_replacements++;
129 }
130
131 void merge_base_index(struct index_state *istate)
132 {
133         struct split_index *si = istate->split_index;
134         unsigned int i;
135
136         mark_base_index_entries(si->base);
137
138         si->saved_cache     = istate->cache;
139         si->saved_cache_nr  = istate->cache_nr;
140         istate->cache_nr    = si->base->cache_nr;
141         istate->cache       = NULL;
142         istate->cache_alloc = 0;
143         ALLOC_GROW(istate->cache, istate->cache_nr, istate->cache_alloc);
144         memcpy(istate->cache, si->base->cache,
145                sizeof(*istate->cache) * istate->cache_nr);
146
147         si->nr_deletions = 0;
148         si->nr_replacements = 0;
149         ewah_each_bit(si->replace_bitmap, replace_entry, istate);
150         ewah_each_bit(si->delete_bitmap, mark_entry_for_delete, istate);
151         if (si->nr_deletions)
152                 remove_marked_cache_entries(istate);
153
154         for (i = si->nr_replacements; i < si->saved_cache_nr; i++) {
155                 if (!ce_namelen(si->saved_cache[i]))
156                         die("corrupt link extension, entry %d should "
157                             "have non-zero length name", i);
158                 add_index_entry(istate, si->saved_cache[i],
159                                 ADD_CACHE_OK_TO_ADD |
160                                 ADD_CACHE_KEEP_CACHE_TREE |
161                                 /*
162                                  * we may have to replay what
163                                  * merge-recursive.c:update_stages()
164                                  * does, which has this flag on
165                                  */
166                                 ADD_CACHE_SKIP_DFCHECK);
167                 si->saved_cache[i] = NULL;
168         }
169
170         ewah_free(si->delete_bitmap);
171         ewah_free(si->replace_bitmap);
172         free(si->saved_cache);
173         si->delete_bitmap  = NULL;
174         si->replace_bitmap = NULL;
175         si->saved_cache    = NULL;
176         si->saved_cache_nr = 0;
177 }
178
179 void prepare_to_write_split_index(struct index_state *istate)
180 {
181         struct split_index *si = init_split_index(istate);
182         struct cache_entry **entries = NULL, *ce;
183         int i, nr_entries = 0, nr_alloc = 0;
184
185         si->delete_bitmap = ewah_new();
186         si->replace_bitmap = ewah_new();
187
188         if (si->base) {
189                 /* Go through istate->cache[] and mark CE_MATCHED to
190                  * entry with positive index. We'll go through
191                  * base->cache[] later to delete all entries in base
192                  * that are not marked eith either CE_MATCHED or
193                  * CE_UPDATE_IN_BASE. If istate->cache[i] is a
194                  * duplicate, deduplicate it.
195                  */
196                 for (i = 0; i < istate->cache_nr; i++) {
197                         struct cache_entry *base;
198                         /* namelen is checked separately */
199                         const unsigned int ondisk_flags =
200                                 CE_STAGEMASK | CE_VALID | CE_EXTENDED_FLAGS;
201                         unsigned int ce_flags, base_flags, ret;
202                         ce = istate->cache[i];
203                         if (!ce->index)
204                                 continue;
205                         if (ce->index > si->base->cache_nr) {
206                                 ce->index = 0;
207                                 continue;
208                         }
209                         ce->ce_flags |= CE_MATCHED; /* or "shared" */
210                         base = si->base->cache[ce->index - 1];
211                         if (ce == base)
212                                 continue;
213                         if (ce->ce_namelen != base->ce_namelen ||
214                             strcmp(ce->name, base->name)) {
215                                 ce->index = 0;
216                                 continue;
217                         }
218                         ce_flags = ce->ce_flags;
219                         base_flags = base->ce_flags;
220                         /* only on-disk flags matter */
221                         ce->ce_flags   &= ondisk_flags;
222                         base->ce_flags &= ondisk_flags;
223                         ret = memcmp(&ce->ce_stat_data, &base->ce_stat_data,
224                                      offsetof(struct cache_entry, name) -
225                                      offsetof(struct cache_entry, ce_stat_data));
226                         ce->ce_flags = ce_flags;
227                         base->ce_flags = base_flags;
228                         if (ret)
229                                 ce->ce_flags |= CE_UPDATE_IN_BASE;
230                         free(base);
231                         si->base->cache[ce->index - 1] = ce;
232                 }
233                 for (i = 0; i < si->base->cache_nr; i++) {
234                         ce = si->base->cache[i];
235                         if ((ce->ce_flags & CE_REMOVE) ||
236                             !(ce->ce_flags & CE_MATCHED))
237                                 ewah_set(si->delete_bitmap, i);
238                         else if (ce->ce_flags & CE_UPDATE_IN_BASE) {
239                                 ewah_set(si->replace_bitmap, i);
240                                 ce->ce_flags |= CE_STRIP_NAME;
241                                 ALLOC_GROW(entries, nr_entries+1, nr_alloc);
242                                 entries[nr_entries++] = ce;
243                         }
244                 }
245         }
246
247         for (i = 0; i < istate->cache_nr; i++) {
248                 ce = istate->cache[i];
249                 if ((!si->base || !ce->index) && !(ce->ce_flags & CE_REMOVE)) {
250                         assert(!(ce->ce_flags & CE_STRIP_NAME));
251                         ALLOC_GROW(entries, nr_entries+1, nr_alloc);
252                         entries[nr_entries++] = ce;
253                 }
254                 ce->ce_flags &= ~CE_MATCHED;
255         }
256
257         /*
258          * take cache[] out temporarily, put entries[] in its place
259          * for writing
260          */
261         si->saved_cache = istate->cache;
262         si->saved_cache_nr = istate->cache_nr;
263         istate->cache = entries;
264         istate->cache_nr = nr_entries;
265 }
266
267 void finish_writing_split_index(struct index_state *istate)
268 {
269         struct split_index *si = init_split_index(istate);
270
271         ewah_free(si->delete_bitmap);
272         ewah_free(si->replace_bitmap);
273         si->delete_bitmap = NULL;
274         si->replace_bitmap = NULL;
275         free(istate->cache);
276         istate->cache = si->saved_cache;
277         istate->cache_nr = si->saved_cache_nr;
278 }
279
280 void discard_split_index(struct index_state *istate)
281 {
282         struct split_index *si = istate->split_index;
283         if (!si)
284                 return;
285         istate->split_index = NULL;
286         si->refcount--;
287         if (si->refcount)
288                 return;
289         if (si->base) {
290                 discard_index(si->base);
291                 free(si->base);
292         }
293         free(si);
294 }
295
296 void save_or_free_index_entry(struct index_state *istate, struct cache_entry *ce)
297 {
298         if (ce->index &&
299             istate->split_index &&
300             istate->split_index->base &&
301             ce->index <= istate->split_index->base->cache_nr &&
302             ce == istate->split_index->base->cache[ce->index - 1])
303                 ce->ce_flags |= CE_REMOVE;
304         else
305                 free(ce);
306 }
307
308 void replace_index_entry_in_base(struct index_state *istate,
309                                  struct cache_entry *old,
310                                  struct cache_entry *new)
311 {
312         if (old->index &&
313             istate->split_index &&
314             istate->split_index->base &&
315             old->index <= istate->split_index->base->cache_nr) {
316                 new->index = old->index;
317                 if (old != istate->split_index->base->cache[new->index - 1])
318                         free(istate->split_index->base->cache[new->index - 1]);
319                 istate->split_index->base->cache[new->index - 1] = new;
320         }
321 }