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87d6a7aa SM |
1 | /* Caching of GDB/DWARF index files. |
2 | ||
3 | Copyright (C) 1994-2018 Free Software Foundation, Inc. | |
4 | ||
5 | This file is part of GDB. | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 3 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | This program is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
19 | ||
20 | #include "defs.h" | |
21 | #include "dwarf-index-cache.h" | |
22 | ||
23 | #include "build-id.h" | |
24 | #include "cli/cli-cmds.h" | |
25 | #include "command.h" | |
26 | #include "common/scoped_mmap.h" | |
27 | #include "common/pathstuff.h" | |
28 | #include "dwarf-index-write.h" | |
29 | #include "dwarf2read.h" | |
30 | #include "objfiles.h" | |
31 | #include "selftest.h" | |
32 | #include <string> | |
33 | #include <stdlib.h> | |
34 | ||
35 | /* When set to 1, show debug messages about the index cache. */ | |
36 | static int debug_index_cache = 0; | |
37 | ||
38 | /* The index cache directory, used for "set/show index-cache directory". */ | |
39 | static char *index_cache_directory = NULL; | |
40 | ||
41 | /* See dwarf-index.cache.h. */ | |
42 | index_cache global_index_cache; | |
43 | ||
44 | /* set/show index-cache commands. */ | |
45 | static cmd_list_element *set_index_cache_prefix_list; | |
46 | static cmd_list_element *show_index_cache_prefix_list; | |
47 | ||
48 | /* A cheap (as in low-quality) recursive mkdir. Try to create all the parents | |
49 | directories up to DIR and DIR itself. Stop if we hit an error along the way. | |
50 | There is no attempt to remove created directories in case of failure. */ | |
51 | ||
52 | static void | |
53 | mkdir_recursive (const char *dir) | |
54 | { | |
55 | gdb::unique_xmalloc_ptr<char> holder (xstrdup (dir)); | |
56 | char * const start = holder.get (); | |
57 | char *component_start = start; | |
58 | char *component_end = start; | |
59 | ||
60 | while (1) | |
61 | { | |
62 | /* Find the beginning of the next component. */ | |
63 | while (*component_start == '/') | |
64 | component_start++; | |
65 | ||
66 | /* Are we done? */ | |
67 | if (*component_start == '\0') | |
68 | return; | |
69 | ||
70 | /* Find the slash or null-terminator after this component. */ | |
71 | component_end = component_start; | |
72 | while (*component_end != '/' && *component_end != '\0') | |
73 | component_end++; | |
74 | ||
75 | /* Temporarily replace the slash with a null terminator, so we can create | |
76 | the directory up to this component. */ | |
77 | char saved_char = *component_end; | |
78 | *component_end = '\0'; | |
79 | ||
80 | /* If we get EEXIST and the existing path is a directory, then we're | |
81 | happy. If it exists, but it's a regular file and this is not the last | |
82 | component, we'll fail at the next component. If this is the last | |
83 | component, the caller will fail with ENOTDIR when trying to | |
84 | open/create a file under that path. */ | |
85 | if (mkdir (start, 0700) != 0) | |
86 | if (errno != EEXIST) | |
87 | return; | |
88 | ||
89 | /* Restore the overwritten char. */ | |
90 | *component_end = saved_char; | |
91 | component_start = component_end; | |
92 | } | |
93 | } | |
94 | ||
95 | /* Default destructor of index_cache_resource. */ | |
96 | index_cache_resource::~index_cache_resource () = default; | |
97 | ||
98 | /* See dwarf-index-cache.h. */ | |
99 | ||
100 | void | |
101 | index_cache::set_directory (std::string dir) | |
102 | { | |
103 | gdb_assert (!dir.empty ()); | |
104 | ||
105 | m_dir = std::move (dir); | |
106 | ||
107 | if (debug_index_cache) | |
108 | printf_unfiltered ("index cache: now using directory %s\n", m_dir.c_str ()); | |
109 | } | |
110 | ||
111 | /* See dwarf-index-cache.h. */ | |
112 | ||
113 | void | |
114 | index_cache::enable () | |
115 | { | |
116 | if (debug_index_cache) | |
117 | printf_unfiltered ("index cache: enabling (%s)\n", m_dir.c_str ()); | |
118 | ||
119 | m_enabled = true; | |
120 | } | |
121 | ||
122 | /* See dwarf-index-cache.h. */ | |
123 | ||
124 | void | |
125 | index_cache::disable () | |
126 | { | |
127 | if (debug_index_cache) | |
128 | printf_unfiltered ("index cache: disabling\n"); | |
129 | ||
130 | m_enabled = false; | |
131 | } | |
132 | ||
133 | /* See dwarf-index-cache.h. */ | |
134 | ||
135 | void | |
136 | index_cache::store (struct dwarf2_per_objfile *dwarf2_per_objfile) | |
137 | { | |
138 | objfile *obj = dwarf2_per_objfile->objfile; | |
139 | ||
140 | if (!enabled ()) | |
141 | return; | |
142 | ||
143 | const bfd_build_id *build_id = build_id_bfd_get (obj->obfd); | |
144 | if (build_id == nullptr) | |
145 | { | |
146 | if (debug_index_cache) | |
147 | printf_unfiltered ("index cache: objfile %s has no build id\n", | |
148 | objfile_name (obj)); | |
149 | return; | |
150 | } | |
151 | ||
152 | if (m_dir.empty ()) | |
153 | { | |
154 | warning (_("The index cache directory name is empty, skipping store.")); | |
155 | return; | |
156 | } | |
157 | ||
158 | std::string build_id_str = build_id_to_string (build_id); | |
159 | ||
160 | TRY | |
161 | { | |
162 | /* Try to create the containing directory. */ | |
163 | mkdir_recursive (m_dir.c_str ()); | |
164 | ||
165 | if (debug_index_cache) | |
166 | printf_unfiltered ("index cache: writing index cache for objfile %s\n", | |
167 | objfile_name (obj)); | |
168 | ||
169 | /* Write the index itself to the directory, using the build id as the | |
170 | filename. */ | |
171 | write_psymtabs_to_index (dwarf2_per_objfile, m_dir.c_str (), | |
172 | build_id_str.c_str (), dw_index_kind::GDB_INDEX); | |
173 | } | |
174 | CATCH (except, RETURN_MASK_ERROR) | |
175 | { | |
176 | if (debug_index_cache) | |
177 | printf_unfiltered ("index cache: couldn't store index cache for objfile " | |
178 | "%s: %s", objfile_name (obj), except.message); | |
179 | } | |
180 | END_CATCH | |
181 | } | |
182 | ||
183 | #if HAVE_SYS_MMAN_H | |
184 | ||
185 | /* Hold the resources for an mmapped index file. */ | |
186 | ||
187 | struct index_cache_resource_mmap final : public index_cache_resource | |
188 | { | |
189 | /* Try to mmap FILENAME. Throw an exception on failure, including if the | |
190 | file doesn't exist. */ | |
191 | index_cache_resource_mmap (const char *filename) | |
192 | : mapping (mmap_file (filename)) | |
193 | {} | |
194 | ||
195 | scoped_mmap mapping; | |
196 | }; | |
197 | ||
198 | /* See dwarf-index-cache.h. */ | |
199 | ||
200 | gdb::array_view<const gdb_byte> | |
201 | index_cache::lookup_gdb_index (const bfd_build_id *build_id, | |
202 | std::unique_ptr<index_cache_resource> *resource) | |
203 | { | |
204 | if (!enabled ()) | |
205 | return {}; | |
206 | ||
207 | if (m_dir.empty ()) | |
208 | { | |
209 | warning (_("The index cache directory name is empty, skipping cache " | |
210 | "lookup.")); | |
211 | return {}; | |
212 | } | |
213 | ||
214 | /* Compute where we would expect a gdb index file for this build id to be. */ | |
215 | std::string filename = make_index_filename (build_id, INDEX4_SUFFIX); | |
216 | ||
217 | TRY | |
218 | { | |
219 | if (debug_index_cache) | |
220 | printf_unfiltered ("index cache: trying to read %s\n", | |
221 | filename.c_str ()); | |
222 | ||
223 | /* Try to map that file. */ | |
224 | index_cache_resource_mmap *mmap_resource | |
225 | = new index_cache_resource_mmap (filename.c_str ()); | |
226 | ||
227 | /* Yay, it worked! Hand the resource to the caller. */ | |
228 | resource->reset (mmap_resource); | |
229 | ||
230 | return gdb::array_view<const gdb_byte> | |
231 | ((const gdb_byte *) mmap_resource->mapping.get (), | |
232 | mmap_resource->mapping.size ()); | |
233 | } | |
234 | CATCH (except, RETURN_MASK_ERROR) | |
235 | { | |
236 | if (debug_index_cache) | |
237 | printf_unfiltered ("index cache: couldn't read %s: %s\n", | |
238 | filename.c_str (), except.message); | |
239 | } | |
240 | END_CATCH | |
241 | ||
242 | return {}; | |
243 | } | |
244 | ||
245 | #else /* !HAVE_SYS_MMAN_H */ | |
246 | ||
247 | /* See dwarf-index-cache.h. This is a no-op on unsupported systems. */ | |
248 | ||
249 | gdb::array_view<const gdb_byte> | |
250 | index_cache::lookup_gdb_index (const bfd_build_id *build_id, | |
251 | std::unique_ptr<index_cache_resource> *resource) | |
252 | { | |
253 | return {}; | |
254 | } | |
255 | ||
256 | #endif | |
257 | ||
258 | /* See dwarf-index-cache.h. */ | |
259 | ||
260 | std::string | |
261 | index_cache::make_index_filename (const bfd_build_id *build_id, | |
262 | const char *suffix) const | |
263 | { | |
264 | std::string build_id_str = build_id_to_string (build_id); | |
265 | ||
266 | return m_dir + SLASH_STRING + build_id_str + suffix; | |
267 | } | |
268 | ||
269 | /* "set index-cache" handler. */ | |
270 | ||
271 | static void | |
272 | set_index_cache_command (const char *arg, int from_tty) | |
273 | { | |
274 | printf_unfiltered (_("\ | |
275 | Missing arguments. See \"help set index-cache\" for help.\n")); | |
276 | } | |
277 | ||
278 | /* True when we are executing "show index-cache". This is used to improve the | |
279 | printout a little bit. */ | |
280 | static bool in_show_index_cache_command = false; | |
281 | ||
282 | /* "show index-cache" handler. */ | |
283 | ||
284 | static void | |
285 | show_index_cache_command (const char *arg, int from_tty) | |
286 | { | |
287 | /* Note that we are executing "show index-cache". */ | |
288 | auto restore_flag = make_scoped_restore (&in_show_index_cache_command, true); | |
289 | ||
290 | /* Call all "show index-cache" subcommands. */ | |
291 | cmd_show_list (show_index_cache_prefix_list, from_tty, ""); | |
292 | ||
293 | printf_unfiltered ("\n"); | |
294 | printf_unfiltered | |
295 | (_("The index cache is currently %s.\n"), | |
296 | global_index_cache.enabled () ? _("enabled") : _("disabled")); | |
297 | } | |
298 | ||
299 | /* "set index-cache on" handler. */ | |
300 | ||
301 | static void | |
302 | set_index_cache_on_command (const char *arg, int from_tty) | |
303 | { | |
304 | global_index_cache.enable (); | |
305 | } | |
306 | ||
307 | /* "set index-cache off" handler. */ | |
308 | ||
309 | static void | |
310 | set_index_cache_off_command (const char *arg, int from_tty) | |
311 | { | |
312 | global_index_cache.disable (); | |
313 | } | |
314 | ||
315 | /* "set index-cache directory" handler. */ | |
316 | ||
317 | static void | |
318 | set_index_cache_directory_command (const char *arg, int from_tty, | |
319 | cmd_list_element *element) | |
320 | { | |
321 | /* Make sure the index cache directory is absolute and tilde-expanded. */ | |
322 | gdb::unique_xmalloc_ptr<char> abs (gdb_abspath (index_cache_directory)); | |
323 | xfree (index_cache_directory); | |
324 | index_cache_directory = abs.release (); | |
325 | global_index_cache.set_directory (index_cache_directory); | |
326 | } | |
327 | ||
328 | /* "show index-cache stats" handler. */ | |
329 | ||
330 | static void | |
331 | show_index_cache_stats_command (const char *arg, int from_tty) | |
332 | { | |
333 | const char *indent = ""; | |
334 | ||
335 | /* If this command is invoked through "show index-cache", make the display a | |
336 | bit nicer. */ | |
337 | if (in_show_index_cache_command) | |
338 | { | |
339 | indent = " "; | |
340 | printf_unfiltered ("\n"); | |
341 | } | |
342 | ||
343 | printf_unfiltered (_("%s Cache hits (this session): %u\n"), | |
344 | indent, global_index_cache.n_hits ()); | |
345 | printf_unfiltered (_("%sCache misses (this session): %u\n"), | |
346 | indent, global_index_cache.n_misses ()); | |
347 | } | |
348 | ||
349 | #if GDB_SELF_TEST && defined (HAVE_MKDTEMP) | |
350 | namespace selftests | |
351 | { | |
352 | ||
353 | /* Try to create DIR using mkdir_recursive and make sure it exists. */ | |
354 | ||
355 | static bool | |
356 | create_dir_and_check (const char *dir) | |
357 | { | |
358 | mkdir_recursive (dir); | |
359 | ||
360 | struct stat st; | |
361 | if (stat (dir, &st) != 0) | |
83c8d318 | 362 | perror_with_name (("stat")); |
87d6a7aa SM |
363 | |
364 | return (st.st_mode & S_IFDIR) != 0; | |
365 | } | |
366 | ||
367 | /* Test mkdir_recursive. */ | |
368 | ||
369 | static void | |
370 | test_mkdir_recursive () | |
371 | { | |
372 | char base[] = "/tmp/gdb-selftests-XXXXXX"; | |
373 | ||
374 | if (mkdtemp (base) == NULL) | |
83c8d318 | 375 | perror_with_name (("mkdtemp")); |
87d6a7aa SM |
376 | |
377 | /* Try not to leave leftover directories. */ | |
378 | struct cleanup_dirs { | |
379 | cleanup_dirs (const char *base) | |
380 | : m_base (base) | |
381 | {} | |
382 | ||
383 | ~cleanup_dirs () { | |
384 | rmdir (string_printf ("%s/a/b/c/d/e", m_base).c_str ()); | |
385 | rmdir (string_printf ("%s/a/b/c/d", m_base).c_str ()); | |
386 | rmdir (string_printf ("%s/a/b/c", m_base).c_str ()); | |
387 | rmdir (string_printf ("%s/a/b", m_base).c_str ()); | |
388 | rmdir (string_printf ("%s/a", m_base).c_str ()); | |
389 | rmdir (m_base); | |
390 | } | |
391 | ||
392 | private: | |
393 | const char *m_base; | |
394 | } cleanup_dirs (base); | |
395 | ||
396 | std::string dir = string_printf ("%s/a/b", base); | |
397 | SELF_CHECK (create_dir_and_check (dir.c_str ())); | |
398 | ||
399 | dir = string_printf ("%s/a/b/c//d/e/", base); | |
400 | SELF_CHECK (create_dir_and_check (dir.c_str ())); | |
401 | } | |
402 | } | |
403 | #endif /* GDB_SELF_TEST && defined (HAVE_MKDTEMP) */ | |
404 | ||
405 | void | |
406 | _initialize_index_cache () | |
407 | { | |
408 | /* Set the default index cache directory. */ | |
409 | std::string cache_dir = get_standard_cache_dir (); | |
410 | if (!cache_dir.empty ()) | |
411 | { | |
412 | index_cache_directory = xstrdup (cache_dir.c_str ()); | |
413 | global_index_cache.set_directory (std::move (cache_dir)); | |
414 | } | |
415 | else | |
416 | warning (_("Couldn't determine a path for the index cache directory.")); | |
417 | ||
418 | /* set index-cache */ | |
419 | add_prefix_cmd ("index-cache", class_files, set_index_cache_command, | |
420 | _("Set index-cache options"), &set_index_cache_prefix_list, | |
421 | "set index-cache ", false, &setlist); | |
422 | ||
423 | /* show index-cache */ | |
424 | add_prefix_cmd ("index-cache", class_files, show_index_cache_command, | |
425 | _("Show index-cache options"), &show_index_cache_prefix_list, | |
426 | "show index-cache ", false, &showlist); | |
427 | ||
428 | /* set index-cache on */ | |
429 | add_cmd ("on", class_files, set_index_cache_on_command, | |
430 | _("Enable the index cache."), &set_index_cache_prefix_list); | |
431 | ||
432 | /* set index-cache off */ | |
433 | add_cmd ("off", class_files, set_index_cache_off_command, | |
434 | _("Disable the index cache."), &set_index_cache_prefix_list); | |
435 | ||
436 | /* set index-cache directory */ | |
437 | add_setshow_filename_cmd ("directory", class_files, &index_cache_directory, | |
438 | _("Set the directory of the index cache."), | |
439 | _("Show the directory of the index cache."), | |
440 | NULL, | |
441 | set_index_cache_directory_command, NULL, | |
442 | &set_index_cache_prefix_list, | |
443 | &show_index_cache_prefix_list); | |
444 | ||
445 | /* show index-cache stats */ | |
446 | add_cmd ("stats", class_files, show_index_cache_stats_command, | |
447 | _("Show some stats about the index cache."), | |
448 | &show_index_cache_prefix_list); | |
449 | ||
450 | /* set debug index-cache */ | |
451 | add_setshow_boolean_cmd ("index-cache", class_maintenance, | |
452 | &debug_index_cache, | |
453 | _("Set display of index-cache debug messages."), | |
454 | _("Show display of index-cache debug messages."), | |
455 | _("\ | |
456 | When non-zero, debugging output for the index cache is displayed."), | |
457 | NULL, NULL, | |
458 | &setdebuglist, &showdebuglist); | |
459 | ||
460 | #if GDB_SELF_TEST && defined (HAVE_MKDTEMP) | |
461 | selftests::register_test ("mkdir_recursive", selftests::test_mkdir_recursive); | |
462 | #endif | |
463 | } |