tmp-objdir.c

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