tmp-objdir.c

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