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