1 #include "cache.h"
2 #include "config.h"
3 #include "dir.h"
4 #include "ewah/ewok.h"
5 #include "fsmonitor.h"
6 #include "run-command.h"
7 #include "strbuf.h"
8
9 #define INDEX_EXTENSION_VERSION1 (1)
10 #define INDEX_EXTENSION_VERSION2 (2)
11 #define HOOK_INTERFACE_VERSION1 (1)
12 #define HOOK_INTERFACE_VERSION2 (2)
13
14 struct trace_key trace_fsmonitor = TRACE_KEY_INIT(FSMONITOR);
15
assert_index_minimum(struct index_state * istate,size_t pos)16 static void assert_index_minimum(struct index_state *istate, size_t pos)
17 {
18 if (pos > istate->cache_nr)
19 BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
20 (uintmax_t)pos, istate->cache_nr);
21 }
22
fsmonitor_ewah_callback(size_t pos,void * is)23 static void fsmonitor_ewah_callback(size_t pos, void *is)
24 {
25 struct index_state *istate = (struct index_state *)is;
26 struct cache_entry *ce;
27
28 assert_index_minimum(istate, pos + 1);
29
30 ce = istate->cache[pos];
31 ce->ce_flags &= ~CE_FSMONITOR_VALID;
32 }
33
fsmonitor_hook_version(void)34 static int fsmonitor_hook_version(void)
35 {
36 int hook_version;
37
38 if (git_config_get_int("core.fsmonitorhookversion", &hook_version))
39 return -1;
40
41 if (hook_version == HOOK_INTERFACE_VERSION1 ||
42 hook_version == HOOK_INTERFACE_VERSION2)
43 return hook_version;
44
45 warning("Invalid hook version '%i' in core.fsmonitorhookversion. "
46 "Must be 1 or 2.", hook_version);
47 return -1;
48 }
49
read_fsmonitor_extension(struct index_state * istate,const void * data,unsigned long sz)50 int read_fsmonitor_extension(struct index_state *istate, const void *data,
51 unsigned long sz)
52 {
53 const char *index = data;
54 uint32_t hdr_version;
55 uint32_t ewah_size;
56 struct ewah_bitmap *fsmonitor_dirty;
57 int ret;
58 uint64_t timestamp;
59 struct strbuf last_update = STRBUF_INIT;
60
61 if (sz < sizeof(uint32_t) + 1 + sizeof(uint32_t))
62 return error("corrupt fsmonitor extension (too short)");
63
64 hdr_version = get_be32(index);
65 index += sizeof(uint32_t);
66 if (hdr_version == INDEX_EXTENSION_VERSION1) {
67 timestamp = get_be64(index);
68 strbuf_addf(&last_update, "%"PRIu64"", timestamp);
69 index += sizeof(uint64_t);
70 } else if (hdr_version == INDEX_EXTENSION_VERSION2) {
71 strbuf_addstr(&last_update, index);
72 index += last_update.len + 1;
73 } else {
74 return error("bad fsmonitor version %d", hdr_version);
75 }
76
77 istate->fsmonitor_last_update = strbuf_detach(&last_update, NULL);
78
79 ewah_size = get_be32(index);
80 index += sizeof(uint32_t);
81
82 fsmonitor_dirty = ewah_new();
83 ret = ewah_read_mmap(fsmonitor_dirty, index, ewah_size);
84 if (ret != ewah_size) {
85 ewah_free(fsmonitor_dirty);
86 return error("failed to parse ewah bitmap reading fsmonitor index extension");
87 }
88 istate->fsmonitor_dirty = fsmonitor_dirty;
89
90 if (!istate->split_index)
91 assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
92
93 trace2_data_string("index", NULL, "extension/fsmn/read/token",
94 istate->fsmonitor_last_update);
95 trace_printf_key(&trace_fsmonitor,
96 "read fsmonitor extension successful '%s'",
97 istate->fsmonitor_last_update);
98 return 0;
99 }
100
fill_fsmonitor_bitmap(struct index_state * istate)101 void fill_fsmonitor_bitmap(struct index_state *istate)
102 {
103 unsigned int i, skipped = 0;
104 istate->fsmonitor_dirty = ewah_new();
105 for (i = 0; i < istate->cache_nr; i++) {
106 if (istate->cache[i]->ce_flags & CE_REMOVE)
107 skipped++;
108 else if (!(istate->cache[i]->ce_flags & CE_FSMONITOR_VALID))
109 ewah_set(istate->fsmonitor_dirty, i - skipped);
110 }
111 }
112
write_fsmonitor_extension(struct strbuf * sb,struct index_state * istate)113 void write_fsmonitor_extension(struct strbuf *sb, struct index_state *istate)
114 {
115 uint32_t hdr_version;
116 uint32_t ewah_start;
117 uint32_t ewah_size = 0;
118 int fixup = 0;
119
120 if (!istate->split_index)
121 assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
122
123 put_be32(&hdr_version, INDEX_EXTENSION_VERSION2);
124 strbuf_add(sb, &hdr_version, sizeof(uint32_t));
125
126 strbuf_addstr(sb, istate->fsmonitor_last_update);
127 strbuf_addch(sb, 0); /* Want to keep a NUL */
128
129 fixup = sb->len;
130 strbuf_add(sb, &ewah_size, sizeof(uint32_t)); /* we'll fix this up later */
131
132 ewah_start = sb->len;
133 ewah_serialize_strbuf(istate->fsmonitor_dirty, sb);
134 ewah_free(istate->fsmonitor_dirty);
135 istate->fsmonitor_dirty = NULL;
136
137 /* fix up size field */
138 put_be32(&ewah_size, sb->len - ewah_start);
139 memcpy(sb->buf + fixup, &ewah_size, sizeof(uint32_t));
140
141 trace2_data_string("index", NULL, "extension/fsmn/write/token",
142 istate->fsmonitor_last_update);
143 trace_printf_key(&trace_fsmonitor,
144 "write fsmonitor extension successful '%s'",
145 istate->fsmonitor_last_update);
146 }
147
148 /*
149 * Call the query-fsmonitor hook passing the last update token of the saved results.
150 */
query_fsmonitor(int version,const char * last_update,struct strbuf * query_result)151 static int query_fsmonitor(int version, const char *last_update, struct strbuf *query_result)
152 {
153 struct child_process cp = CHILD_PROCESS_INIT;
154 int result;
155
156 if (!core_fsmonitor)
157 return -1;
158
159 strvec_push(&cp.args, core_fsmonitor);
160 strvec_pushf(&cp.args, "%d", version);
161 strvec_pushf(&cp.args, "%s", last_update);
162 cp.use_shell = 1;
163 cp.dir = get_git_work_tree();
164
165 trace2_region_enter("fsm_hook", "query", NULL);
166
167 result = capture_command(&cp, query_result, 1024);
168
169 if (result)
170 trace2_data_intmax("fsm_hook", NULL, "query/failed", result);
171 else {
172 trace2_data_intmax("fsm_hook", NULL, "query/response-length",
173 query_result->len);
174
175 if (fsmonitor_is_trivial_response(query_result))
176 trace2_data_intmax("fsm_hook", NULL,
177 "query/trivial-response", 1);
178 }
179
180 trace2_region_leave("fsm_hook", "query", NULL);
181
182 return result;
183 }
184
fsmonitor_is_trivial_response(const struct strbuf * query_result)185 int fsmonitor_is_trivial_response(const struct strbuf *query_result)
186 {
187 static char trivial_response[3] = { '\0', '/', '\0' };
188
189 return query_result->len >= 3 &&
190 !memcmp(trivial_response,
191 &query_result->buf[query_result->len - 3], 3);
192 }
193
fsmonitor_refresh_callback(struct index_state * istate,char * name)194 static void fsmonitor_refresh_callback(struct index_state *istate, char *name)
195 {
196 int i, len = strlen(name);
197 if (name[len - 1] == '/') {
198
199 /*
200 * TODO We should binary search to find the first path with
201 * TODO this directory prefix. Then linearly update entries
202 * TODO while the prefix matches. Taking care to search without
203 * TODO the trailing slash -- because '/' sorts after a few
204 * TODO interesting special chars, like '.' and ' '.
205 */
206
207 /* Mark all entries for the folder invalid */
208 for (i = 0; i < istate->cache_nr; i++) {
209 if (istate->cache[i]->ce_flags & CE_FSMONITOR_VALID &&
210 starts_with(istate->cache[i]->name, name))
211 istate->cache[i]->ce_flags &= ~CE_FSMONITOR_VALID;
212 }
213 /* Need to remove the / from the path for the untracked cache */
214 name[len - 1] = '\0';
215 } else {
216 int pos = index_name_pos(istate, name, strlen(name));
217
218 if (pos >= 0) {
219 struct cache_entry *ce = istate->cache[pos];
220 ce->ce_flags &= ~CE_FSMONITOR_VALID;
221 }
222 }
223
224 /*
225 * Mark the untracked cache dirty even if it wasn't found in the index
226 * as it could be a new untracked file.
227 */
228 trace_printf_key(&trace_fsmonitor, "fsmonitor_refresh_callback '%s'", name);
229 untracked_cache_invalidate_path(istate, name, 0);
230 }
231
refresh_fsmonitor(struct index_state * istate)232 void refresh_fsmonitor(struct index_state *istate)
233 {
234 struct strbuf query_result = STRBUF_INIT;
235 int query_success = 0, hook_version = -1;
236 size_t bol = 0; /* beginning of line */
237 uint64_t last_update;
238 struct strbuf last_update_token = STRBUF_INIT;
239 char *buf;
240 unsigned int i;
241
242 if (!core_fsmonitor || istate->fsmonitor_has_run_once)
243 return;
244
245 hook_version = fsmonitor_hook_version();
246
247 istate->fsmonitor_has_run_once = 1;
248
249 trace_printf_key(&trace_fsmonitor, "refresh fsmonitor");
250 /*
251 * This could be racy so save the date/time now and query_fsmonitor
252 * should be inclusive to ensure we don't miss potential changes.
253 */
254 last_update = getnanotime();
255 if (hook_version == HOOK_INTERFACE_VERSION1)
256 strbuf_addf(&last_update_token, "%"PRIu64"", last_update);
257
258 /*
259 * If we have a last update token, call query_fsmonitor for the set of
260 * changes since that token, else assume everything is possibly dirty
261 * and check it all.
262 */
263 if (istate->fsmonitor_last_update) {
264 if (hook_version == -1 || hook_version == HOOK_INTERFACE_VERSION2) {
265 query_success = !query_fsmonitor(HOOK_INTERFACE_VERSION2,
266 istate->fsmonitor_last_update, &query_result);
267
268 if (query_success) {
269 if (hook_version < 0)
270 hook_version = HOOK_INTERFACE_VERSION2;
271
272 /*
273 * First entry will be the last update token
274 * Need to use a char * variable because static
275 * analysis was suggesting to use strbuf_addbuf
276 * but we don't want to copy the entire strbuf
277 * only the chars up to the first NUL
278 */
279 buf = query_result.buf;
280 strbuf_addstr(&last_update_token, buf);
281 if (!last_update_token.len) {
282 warning("Empty last update token.");
283 query_success = 0;
284 } else {
285 bol = last_update_token.len + 1;
286 }
287 } else if (hook_version < 0) {
288 hook_version = HOOK_INTERFACE_VERSION1;
289 if (!last_update_token.len)
290 strbuf_addf(&last_update_token, "%"PRIu64"", last_update);
291 }
292 }
293
294 if (hook_version == HOOK_INTERFACE_VERSION1) {
295 query_success = !query_fsmonitor(HOOK_INTERFACE_VERSION1,
296 istate->fsmonitor_last_update, &query_result);
297 }
298
299 trace_performance_since(last_update, "fsmonitor process '%s'", core_fsmonitor);
300 trace_printf_key(&trace_fsmonitor, "fsmonitor process '%s' returned %s",
301 core_fsmonitor, query_success ? "success" : "failure");
302 }
303
304 /* a fsmonitor process can return '/' to indicate all entries are invalid */
305 if (query_success && query_result.buf[bol] != '/') {
306 /* Mark all entries returned by the monitor as dirty */
307 buf = query_result.buf;
308 for (i = bol; i < query_result.len; i++) {
309 if (buf[i] != '\0')
310 continue;
311 fsmonitor_refresh_callback(istate, buf + bol);
312 bol = i + 1;
313 }
314 if (bol < query_result.len)
315 fsmonitor_refresh_callback(istate, buf + bol);
316
317 /* Now mark the untracked cache for fsmonitor usage */
318 if (istate->untracked)
319 istate->untracked->use_fsmonitor = 1;
320 } else {
321
322 /* We only want to run the post index changed hook if we've actually changed entries, so keep track
323 * if we actually changed entries or not */
324 int is_cache_changed = 0;
325 /* Mark all entries invalid */
326 for (i = 0; i < istate->cache_nr; i++) {
327 if (istate->cache[i]->ce_flags & CE_FSMONITOR_VALID) {
328 is_cache_changed = 1;
329 istate->cache[i]->ce_flags &= ~CE_FSMONITOR_VALID;
330 }
331 }
332
333 /* If we're going to check every file, ensure we save the results */
334 if (is_cache_changed)
335 istate->cache_changed |= FSMONITOR_CHANGED;
336
337 if (istate->untracked)
338 istate->untracked->use_fsmonitor = 0;
339 }
340 strbuf_release(&query_result);
341
342 /* Now that we've updated istate, save the last_update_token */
343 FREE_AND_NULL(istate->fsmonitor_last_update);
344 istate->fsmonitor_last_update = strbuf_detach(&last_update_token, NULL);
345 }
346
347 /*
348 * The caller wants to turn on FSMonitor. And when the caller writes
349 * the index to disk, a FSMonitor extension should be included. This
350 * requires that `istate->fsmonitor_last_update` not be NULL. But we
351 * have not actually talked to a FSMonitor process yet, so we don't
352 * have an initial value for this field.
353 *
354 * For a protocol V1 FSMonitor process, this field is a formatted
355 * "nanoseconds since epoch" field. However, for a protocol V2
356 * FSMonitor process, this field is an opaque token.
357 *
358 * Historically, `add_fsmonitor()` has initialized this field to the
359 * current time for protocol V1 processes. There are lots of race
360 * conditions here, but that code has shipped...
361 *
362 * The only true solution is to use a V2 FSMonitor and get a current
363 * or default token value (that it understands), but we cannot do that
364 * until we have actually talked to an instance of the FSMonitor process
365 * (but the protocol requires that we send a token first...).
366 *
367 * For simplicity, just initialize like we have a V1 process and require
368 * that V2 processes adapt.
369 */
initialize_fsmonitor_last_update(struct index_state * istate)370 static void initialize_fsmonitor_last_update(struct index_state *istate)
371 {
372 struct strbuf last_update = STRBUF_INIT;
373
374 strbuf_addf(&last_update, "%"PRIu64"", getnanotime());
375 istate->fsmonitor_last_update = strbuf_detach(&last_update, NULL);
376 }
377
add_fsmonitor(struct index_state * istate)378 void add_fsmonitor(struct index_state *istate)
379 {
380 unsigned int i;
381
382 if (!istate->fsmonitor_last_update) {
383 trace_printf_key(&trace_fsmonitor, "add fsmonitor");
384 istate->cache_changed |= FSMONITOR_CHANGED;
385 initialize_fsmonitor_last_update(istate);
386
387 /* reset the fsmonitor state */
388 for (i = 0; i < istate->cache_nr; i++)
389 istate->cache[i]->ce_flags &= ~CE_FSMONITOR_VALID;
390
391 /* reset the untracked cache */
392 if (istate->untracked) {
393 add_untracked_cache(istate);
394 istate->untracked->use_fsmonitor = 1;
395 }
396
397 /* Update the fsmonitor state */
398 refresh_fsmonitor(istate);
399 }
400 }
401
remove_fsmonitor(struct index_state * istate)402 void remove_fsmonitor(struct index_state *istate)
403 {
404 if (istate->fsmonitor_last_update) {
405 trace_printf_key(&trace_fsmonitor, "remove fsmonitor");
406 istate->cache_changed |= FSMONITOR_CHANGED;
407 FREE_AND_NULL(istate->fsmonitor_last_update);
408 }
409 }
410
tweak_fsmonitor(struct index_state * istate)411 void tweak_fsmonitor(struct index_state *istate)
412 {
413 unsigned int i;
414 int fsmonitor_enabled = git_config_get_fsmonitor();
415
416 if (istate->fsmonitor_dirty) {
417 if (fsmonitor_enabled) {
418 /* Mark all entries valid */
419 for (i = 0; i < istate->cache_nr; i++) {
420 istate->cache[i]->ce_flags |= CE_FSMONITOR_VALID;
421 }
422
423 /* Mark all previously saved entries as dirty */
424 assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
425 ewah_each_bit(istate->fsmonitor_dirty, fsmonitor_ewah_callback, istate);
426
427 refresh_fsmonitor(istate);
428 }
429
430 ewah_free(istate->fsmonitor_dirty);
431 istate->fsmonitor_dirty = NULL;
432 }
433
434 switch (fsmonitor_enabled) {
435 case -1: /* keep: do nothing */
436 break;
437 case 0: /* false */
438 remove_fsmonitor(istate);
439 break;
440 case 1: /* true */
441 add_fsmonitor(istate);
442 break;
443 default: /* unknown value: do nothing */
444 break;
445 }
446 }
447