tmp-objdir.c

   1 #include "cache.h"
   2 #include "tmp-objdir.h"
   3 #include "chdir-notify.h"
   4 #include "dir.h"
   5 #include "sigchain.h"
   6 #include "string-list.h"
   7 #include "strbuf.h"
   8 #include "strvec.h"
   9 #include "quote.h"
  10 #include "object-store.h"
  11
  12 struct tmp_objdir {
  13         struct strbuf path;
  14         struct strvec env;
  15         struct object_directory *prev_odb;
  16         int will_destroy;
  17 };
  18
  19 /*
  20  * Allow only one tmp_objdir at a time in a running process, which simplifies
  21  * our signal/atexit cleanup routines.  It's doubtful callers will ever need
  22  * more than one, and we can expand later if so.  You can have many such
  23  * tmp_objdirs simultaneously in many processes, of course.
  24  */
  25 static struct tmp_objdir *the_tmp_objdir;
  26
  27 static void tmp_objdir_free(struct tmp_objdir *t)
  28 {
  29         strbuf_release(&t->path);
  30         strvec_clear(&t->env);
  31         free(t);
  32 }
  33
  34 static int tmp_objdir_destroy_1(struct tmp_objdir *t, int on_signal)
  35 {
  36         int err;
  37
  38         if (!t)
  39                 return 0;
  40
  41         if (t == the_tmp_objdir)
  42                 the_tmp_objdir = NULL;
  43
  44         if (!on_signal && t->prev_odb)
  45                 restore_primary_odb(t->prev_odb, t->path.buf);
  46
  47         /*
  48          * This may use malloc via strbuf_grow(), but we should
  49          * have pre-grown t->path sufficiently so that this
  50          * doesn't happen in practice.
  51          */
  52         err = remove_dir_recursively(&t->path, 0);
  53
  54         /*
  55          * When we are cleaning up due to a signal, we won't bother
  56          * freeing memory; it may cause a deadlock if the signal
  57          * arrived while libc's allocator lock is held.
  58          */
  59         if (!on_signal)
  60                 tmp_objdir_free(t);
  61
  62         return err;
  63 }
  64
  65 int tmp_objdir_destroy(struct tmp_objdir *t)
  66 {
  67         return tmp_objdir_destroy_1(t, 0);
  68 }
  69
  70 static void remove_tmp_objdir(void)
  71 {
  72         tmp_objdir_destroy(the_tmp_objdir);
  73 }
  74
  75 static void remove_tmp_objdir_on_signal(int signo)
  76 {
  77         tmp_objdir_destroy_1(the_tmp_objdir, 1);
  78         sigchain_pop(signo);
  79         raise(signo);
  80 }
  81
  82 void tmp_objdir_discard_objects(struct tmp_objdir *t)
  83 {
  84         remove_dir_recursively(&t->path, REMOVE_DIR_KEEP_TOPLEVEL);
  85 }
  86
  87 /*
  88  * These env_* functions are for setting up the child environment; the
  89  * "replace" variant overrides the value of any existing variable with that
  90  * "key". The "append" variant puts our new value at the end of a list,
  91  * separated by PATH_SEP (which is what separate values in
  92  * GIT_ALTERNATE_OBJECT_DIRECTORIES).
  93  */
  94 static void env_append(struct strvec *env, const char *key, const char *val)
  95 {
  96         struct strbuf quoted = STRBUF_INIT;
  97         const char *old;
  98
  99         /*
 100          * Avoid quoting if it's not necessary, for maximum compatibility
 101          * with older parsers which don't understand the quoting.
 102          */
 103         if (*val == '"' || strchr(val, PATH_SEP)) {
 104                 strbuf_addch(&quoted, '"');
 105                 quote_c_style(val, &quoted, NULL, 1);
 106                 strbuf_addch(&quoted, '"');
 107                 val = quoted.buf;
 108         }
 109
 110         old = getenv(key);
 111         if (!old)
 112                 strvec_pushf(env, "%s=%s", key, val);
 113         else
 114                 strvec_pushf(env, "%s=%s%c%s", key, old, PATH_SEP, val);
 115
 116         strbuf_release(&quoted);
 117 }
 118
 119 static void env_replace(struct strvec *env, const char *key, const char *val)
 120 {
 121         strvec_pushf(env, "%s=%s", key, val);
 122 }
 123
 124 static int setup_tmp_objdir(const char *root)
 125 {
 126         char *path;
 127         int ret = 0;
 128
 129         path = xstrfmt("%s/pack", root);
 130         ret = mkdir(path, 0777);
 131         free(path);
 132
 133         return ret;
 134 }
 135
 136 struct tmp_objdir *tmp_objdir_create(const char *prefix)
 137 {
 138         static int installed_handlers;
 139         struct tmp_objdir *t;
 140
 141         if (the_tmp_objdir)
 142                 BUG("only one tmp_objdir can be used at a time");
 143
 144         t = xcalloc(1, sizeof(*t));
 145         strbuf_init(&t->path, 0);
 146         strvec_init(&t->env);
 147
 148         /*
 149          * Use a string starting with tmp_ so that the builtin/prune.c code
 150          * can recognize any stale objdirs left behind by a crash and delete
 151          * them.
 152          */
 153         strbuf_addf(&t->path, "%s/tmp_objdir-%s-XXXXXX", get_object_directory(), prefix);
 154
 155         /*
 156          * Grow the strbuf beyond any filename we expect to be placed in it.
 157          * If tmp_objdir_destroy() is called by a signal handler, then
 158          * we should be able to use the strbuf to remove files without
 159          * having to call malloc.
 160          */
 161         strbuf_grow(&t->path, 1024);
 162
 163         if (!mkdtemp(t->path.buf)) {
 164                 /* free, not destroy, as we never touched the filesystem */
 165                 tmp_objdir_free(t);
 166                 return NULL;
 167         }
 168
 169         the_tmp_objdir = t;
 170         if (!installed_handlers) {
 171                 atexit(remove_tmp_objdir);
 172                 sigchain_push_common(remove_tmp_objdir_on_signal);
 173                 installed_handlers++;
 174         }
 175
 176         if (setup_tmp_objdir(t->path.buf)) {
 177                 tmp_objdir_destroy(t);
 178                 return NULL;
 179         }
 180
 181         env_append(&t->env, ALTERNATE_DB_ENVIRONMENT,
 182                    absolute_path(get_object_directory()));
 183         env_replace(&t->env, DB_ENVIRONMENT, absolute_path(t->path.buf));
 184         env_replace(&t->env, GIT_QUARANTINE_ENVIRONMENT,
 185                     absolute_path(t->path.buf));
 186
 187         return t;
 188 }
 189
 190 /*
 191  * Make sure we copy packfiles and their associated metafiles in the correct
 192  * order. All of these ends_with checks are slightly expensive to do in
 193  * the midst of a sorting routine, but in practice it shouldn't matter.
 194  * We will have a relatively small number of packfiles to order, and loose
 195  * objects exit early in the first line.
 196  */
 197 static int pack_copy_priority(const char *name)
 198 {
 199         if (!starts_with(name, "pack"))
 200                 return 0;
 201         if (ends_with(name, ".keep"))
 202                 return 1;
 203         if (ends_with(name, ".pack"))
 204                 return 2;
 205         if (ends_with(name, ".rev"))
 206                 return 3;
 207         if (ends_with(name, ".idx"))
 208                 return 4;
 209         return 5;
 210 }
 211
 212 static int pack_copy_cmp(const char *a, const char *b)
 213 {
 214         return pack_copy_priority(a) - pack_copy_priority(b);
 215 }
 216
 217 static int read_dir_paths(struct string_list *out, const char *path)
 218 {
 219         DIR *dh;
 220         struct dirent *de;
 221
 222         dh = opendir(path);
 223         if (!dh)
 224                 return -1;
 225
 226         while ((de = readdir(dh)))
 227                 if (de->d_name[0] != '.')
 228                         string_list_append(out, de->d_name);
 229
 230         closedir(dh);
 231         return 0;
 232 }
 233
 234 static int migrate_paths(struct strbuf *src, struct strbuf *dst);
 235
 236 static int migrate_one(struct strbuf *src, struct strbuf *dst)
 237 {
 238         struct stat st;
 239
 240         if (stat(src->buf, &st) < 0)
 241                 return -1;
 242         if (S_ISDIR(st.st_mode)) {
 243                 if (!mkdir(dst->buf, 0777)) {
 244                         if (adjust_shared_perm(dst->buf))
 245                                 return -1;
 246                 } else if (errno != EEXIST)
 247                         return -1;
 248                 return migrate_paths(src, dst);
 249         }
 250         return finalize_object_file(src->buf, dst->buf);
 251 }
 252
 253 static int migrate_paths(struct strbuf *src, struct strbuf *dst)
 254 {
 255         size_t src_len = src->len, dst_len = dst->len;
 256         struct string_list paths = STRING_LIST_INIT_DUP;
 257         int i;
 258         int ret = 0;
 259
 260         if (read_dir_paths(&paths, src->buf) < 0)
 261                 return -1;
 262         paths.cmp = pack_copy_cmp;
 263         string_list_sort(&paths);
 264
 265         for (i = 0; i < paths.nr; i++) {
 266                 const char *name = paths.items[i].string;
 267
 268                 strbuf_addf(src, "/%s", name);
 269                 strbuf_addf(dst, "/%s", name);
 270
 271                 ret |= migrate_one(src, dst);
 272
 273                 strbuf_setlen(src, src_len);
 274                 strbuf_setlen(dst, dst_len);
 275         }
 276
 277         string_list_clear(&paths, 0);
 278         return ret;
 279 }
 280
 281 int tmp_objdir_migrate(struct tmp_objdir *t)
 282 {
 283         struct strbuf src = STRBUF_INIT, dst = STRBUF_INIT;
 284         int ret;
 285
 286         if (!t)
 287                 return 0;
 288
 289         if (t->prev_odb) {
 290                 if (the_repository->objects->odb->will_destroy)
 291                         BUG("migrating an ODB that was marked for destruction");
 292                 restore_primary_odb(t->prev_odb, t->path.buf);
 293                 t->prev_odb = NULL;
 294         }
 295
 296         strbuf_addbuf(&src, &t->path);
 297         strbuf_addstr(&dst, get_object_directory());
 298
 299         ret = migrate_paths(&src, &dst);
 300
 301         strbuf_release(&src);
 302         strbuf_release(&dst);
 303
 304         tmp_objdir_destroy(t);
 305         return ret;
 306 }
 307
 308 const char **tmp_objdir_env(const struct tmp_objdir *t)
 309 {
 310         if (!t)
 311                 return NULL;
 312         return t->env.v;
 313 }
 314
 315 void tmp_objdir_add_as_alternate(const struct tmp_objdir *t)
 316 {
 317         add_to_alternates_memory(t->path.buf);
 318 }
 319
 320 void tmp_objdir_replace_primary_odb(struct tmp_objdir *t, int will_destroy)
 321 {
 322         if (t->prev_odb)
 323                 BUG("the primary object database is already replaced");
 324         t->prev_odb = set_temporary_primary_odb(t->path.buf, will_destroy);
 325         t->will_destroy = will_destroy;
 326 }
 327
 328 struct tmp_objdir *tmp_objdir_unapply_primary_odb(void)
 329 {
 330         if (!the_tmp_objdir || !the_tmp_objdir->prev_odb)
 331                 return NULL;
 332
 333         restore_primary_odb(the_tmp_objdir->prev_odb, the_tmp_objdir->path.buf);
 334         the_tmp_objdir->prev_odb = NULL;
 335         return the_tmp_objdir;
 336 }
 337
 338 void tmp_objdir_reapply_primary_odb(struct tmp_objdir *t, const char *old_cwd,
 339                 const char *new_cwd)
 340 {
 341         char *path;
 342
 343         path = reparent_relative_path(old_cwd, new_cwd, t->path.buf);
 344         strbuf_reset(&t->path);
 345         strbuf_addstr(&t->path, path);
 346         free(path);
 347         tmp_objdir_replace_primary_odb(t, t->will_destroy);
 348 }