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 /*
  83  * These env_* functions are for setting up the child environment; the
  84  * "replace" variant overrides the value of any existing variable with that
  85  * "key". The "append" variant puts our new value at the end of a list,
  86  * separated by PATH_SEP (which is what separate values in
  87  * GIT_ALTERNATE_OBJECT_DIRECTORIES).
  88  */
  89 static void env_append(struct strvec *env, const char *key, const char *val)
  90 {
  91         struct strbuf quoted = STRBUF_INIT;
  92         const char *old;
  93
  94         /*
  95          * Avoid quoting if it's not necessary, for maximum compatibility
  96          * with older parsers which don't understand the quoting.
  97          */
  98         if (*val == '"' || strchr(val, PATH_SEP)) {
  99                 strbuf_addch(&quoted, '"');
 100                 quote_c_style(val, &quoted, NULL, 1);
 101                 strbuf_addch(&quoted, '"');
 102                 val = quoted.buf;
 103         }
 104
 105         old = getenv(key);
 106         if (!old)
 107                 strvec_pushf(env, "%s=%s", key, val);
 108         else
 109                 strvec_pushf(env, "%s=%s%c%s", key, old, PATH_SEP, val);
 110
 111         strbuf_release(&quoted);
 112 }
 113
 114 static void env_replace(struct strvec *env, const char *key, const char *val)
 115 {
 116         strvec_pushf(env, "%s=%s", key, val);
 117 }
 118
 119 static int setup_tmp_objdir(const char *root)
 120 {
 121         char *path;
 122         int ret = 0;
 123
 124         path = xstrfmt("%s/pack", root);
 125         ret = mkdir(path, 0777);
 126         free(path);
 127
 128         return ret;
 129 }
 130
 131 struct tmp_objdir *tmp_objdir_create(const char *prefix)
 132 {
 133         static int installed_handlers;
 134         struct tmp_objdir *t;
 135
 136         if (the_tmp_objdir)
 137                 BUG("only one tmp_objdir can be used at a time");
 138
 139         t = xcalloc(1, sizeof(*t));
 140         strbuf_init(&t->path, 0);
 141         strvec_init(&t->env);
 142
 143         /*
 144          * Use a string starting with tmp_ so that the builtin/prune.c code
 145          * can recognize any stale objdirs left behind by a crash and delete
 146          * them.
 147          */
 148         strbuf_addf(&t->path, "%s/tmp_objdir-%s-XXXXXX", get_object_directory(), prefix);
 149
 150         /*
 151          * Grow the strbuf beyond any filename we expect to be placed in it.
 152          * If tmp_objdir_destroy() is called by a signal handler, then
 153          * we should be able to use the strbuf to remove files without
 154          * having to call malloc.
 155          */
 156         strbuf_grow(&t->path, 1024);
 157
 158         if (!mkdtemp(t->path.buf)) {
 159                 /* free, not destroy, as we never touched the filesystem */
 160                 tmp_objdir_free(t);
 161                 return NULL;
 162         }
 163
 164         the_tmp_objdir = t;
 165         if (!installed_handlers) {
 166                 atexit(remove_tmp_objdir);
 167                 sigchain_push_common(remove_tmp_objdir_on_signal);
 168                 installed_handlers++;
 169         }
 170
 171         if (setup_tmp_objdir(t->path.buf)) {
 172                 tmp_objdir_destroy(t);
 173                 return NULL;
 174         }
 175
 176         env_append(&t->env, ALTERNATE_DB_ENVIRONMENT,
 177                    absolute_path(get_object_directory()));
 178         env_replace(&t->env, DB_ENVIRONMENT, absolute_path(t->path.buf));
 179         env_replace(&t->env, GIT_QUARANTINE_ENVIRONMENT,
 180                     absolute_path(t->path.buf));
 181
 182         return t;
 183 }
 184
 185 /*
 186  * Make sure we copy packfiles and their associated metafiles in the correct
 187  * order. All of these ends_with checks are slightly expensive to do in
 188  * the midst of a sorting routine, but in practice it shouldn't matter.
 189  * We will have a relatively small number of packfiles to order, and loose
 190  * objects exit early in the first line.
 191  */
 192 static int pack_copy_priority(const char *name)
 193 {
 194         if (!starts_with(name, "pack"))
 195                 return 0;
 196         if (ends_with(name, ".keep"))
 197                 return 1;
 198         if (ends_with(name, ".pack"))
 199                 return 2;
 200         if (ends_with(name, ".rev"))
 201                 return 3;
 202         if (ends_with(name, ".idx"))
 203                 return 4;
 204         return 5;
 205 }
 206
 207 static int pack_copy_cmp(const char *a, const char *b)
 208 {
 209         return pack_copy_priority(a) - pack_copy_priority(b);
 210 }
 211
 212 static int read_dir_paths(struct string_list *out, const char *path)
 213 {
 214         DIR *dh;
 215         struct dirent *de;
 216
 217         dh = opendir(path);
 218         if (!dh)
 219                 return -1;
 220
 221         while ((de = readdir(dh)))
 222                 if (de->d_name[0] != '.')
 223                         string_list_append(out, de->d_name);
 224
 225         closedir(dh);
 226         return 0;
 227 }
 228
 229 static int migrate_paths(struct strbuf *src, struct strbuf *dst);
 230
 231 static int migrate_one(struct strbuf *src, struct strbuf *dst)
 232 {
 233         struct stat st;
 234
 235         if (stat(src->buf, &st) < 0)
 236                 return -1;
 237         if (S_ISDIR(st.st_mode)) {
 238                 if (!mkdir(dst->buf, 0777)) {
 239                         if (adjust_shared_perm(dst->buf))
 240                                 return -1;
 241                 } else if (errno != EEXIST)
 242                         return -1;
 243                 return migrate_paths(src, dst);
 244         }
 245         return finalize_object_file(src->buf, dst->buf);
 246 }
 247
 248 static int migrate_paths(struct strbuf *src, struct strbuf *dst)
 249 {
 250         size_t src_len = src->len, dst_len = dst->len;
 251         struct string_list paths = STRING_LIST_INIT_DUP;
 252         int i;
 253         int ret = 0;
 254
 255         if (read_dir_paths(&paths, src->buf) < 0)
 256                 return -1;
 257         paths.cmp = pack_copy_cmp;
 258         string_list_sort(&paths);
 259
 260         for (i = 0; i < paths.nr; i++) {
 261                 const char *name = paths.items[i].string;
 262
 263                 strbuf_addf(src, "/%s", name);
 264                 strbuf_addf(dst, "/%s", name);
 265
 266                 ret |= migrate_one(src, dst);
 267
 268                 strbuf_setlen(src, src_len);
 269                 strbuf_setlen(dst, dst_len);
 270         }
 271
 272         string_list_clear(&paths, 0);
 273         return ret;
 274 }
 275
 276 int tmp_objdir_migrate(struct tmp_objdir *t)
 277 {
 278         struct strbuf src = STRBUF_INIT, dst = STRBUF_INIT;
 279         int ret;
 280
 281         if (!t)
 282                 return 0;
 283
 284         if (t->prev_odb) {
 285                 if (the_repository->objects->odb->will_destroy)
 286                         BUG("migrating an ODB that was marked for destruction");
 287                 restore_primary_odb(t->prev_odb, t->path.buf);
 288                 t->prev_odb = NULL;
 289         }
 290
 291         strbuf_addbuf(&src, &t->path);
 292         strbuf_addstr(&dst, get_object_directory());
 293
 294         ret = migrate_paths(&src, &dst);
 295
 296         strbuf_release(&src);
 297         strbuf_release(&dst);
 298
 299         tmp_objdir_destroy(t);
 300         return ret;
 301 }
 302
 303 const char **tmp_objdir_env(const struct tmp_objdir *t)
 304 {
 305         if (!t)
 306                 return NULL;
 307         return t->env.v;
 308 }
 309
 310 void tmp_objdir_add_as_alternate(const struct tmp_objdir *t)
 311 {
 312         add_to_alternates_memory(t->path.buf);
 313 }
 314
 315 void tmp_objdir_replace_primary_odb(struct tmp_objdir *t, int will_destroy)
 316 {
 317         if (t->prev_odb)
 318                 BUG("the primary object database is already replaced");
 319         t->prev_odb = set_temporary_primary_odb(t->path.buf, will_destroy);
 320         t->will_destroy = will_destroy;
 321 }
 322
 323 struct tmp_objdir *tmp_objdir_unapply_primary_odb(void)
 324 {
 325         if (!the_tmp_objdir || !the_tmp_objdir->prev_odb)
 326                 return NULL;
 327
 328         restore_primary_odb(the_tmp_objdir->prev_odb, the_tmp_objdir->path.buf);
 329         the_tmp_objdir->prev_odb = NULL;
 330         return the_tmp_objdir;
 331 }
 332
 333 void tmp_objdir_reapply_primary_odb(struct tmp_objdir *t, const char *old_cwd,
 334                 const char *new_cwd)
 335 {
 336         char *path;
 337
 338         path = reparent_relative_path(old_cwd, new_cwd, t->path.buf);
 339         strbuf_reset(&t->path);
 340         strbuf_addstr(&t->path, path);
 341         free(path);
 342         tmp_objdir_replace_primary_odb(t, t->will_destroy);
 343 }