tmp-objdir.c

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