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