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