tmp-objdir.c

   1 #include "cache.h"
   2 #include "tmp-objdir.h"
   3 #include "dir.h"
   4 #include "sigchain.h"
   5 #include "string-list.h"
   6 #include "strbuf.h"
   7 #include "argv-array.h"
   8
   9 struct tmp_objdir {
  10         struct strbuf path;
  11         struct argv_array env;
  12 };
  13
  14 /*
  15  * Allow only one tmp_objdir at a time in a running process, which simplifies
  16  * our signal/atexit cleanup routines.  It's doubtful callers will ever need
  17  * more than one, and we can expand later if so.  You can have many such
  18  * tmp_objdirs simultaneously in many processes, of course.
  19  */
  20 static struct tmp_objdir *the_tmp_objdir;
  21
  22 static void tmp_objdir_free(struct tmp_objdir *t)
  23 {
  24         strbuf_release(&t->path);
  25         argv_array_clear(&t->env);
  26         free(t);
  27 }
  28
  29 static int tmp_objdir_destroy_1(struct tmp_objdir *t, int on_signal)
  30 {
  31         int err;
  32
  33         if (!t)
  34                 return 0;
  35
  36         if (t == the_tmp_objdir)
  37                 the_tmp_objdir = NULL;
  38
  39         /*
  40          * This may use malloc via strbuf_grow(), but we should
  41          * have pre-grown t->path sufficiently so that this
  42          * doesn't happen in practice.
  43          */
  44         err = remove_dir_recursively(&t->path, 0);
  45
  46         /*
  47          * When we are cleaning up due to a signal, we won't bother
  48          * freeing memory; it may cause a deadlock if the signal
  49          * arrived while libc's allocator lock is held.
  50          */
  51         if (!on_signal)
  52                 tmp_objdir_free(t);
  53         return err;
  54 }
  55
  56 int tmp_objdir_destroy(struct tmp_objdir *t)
  57 {
  58         return tmp_objdir_destroy_1(t, 0);
  59 }
  60
  61 static void remove_tmp_objdir(void)
  62 {
  63         tmp_objdir_destroy(the_tmp_objdir);
  64 }
  65
  66 static void remove_tmp_objdir_on_signal(int signo)
  67 {
  68         tmp_objdir_destroy_1(the_tmp_objdir, 1);
  69         sigchain_pop(signo);
  70         raise(signo);
  71 }
  72
  73 /*
  74  * These env_* functions are for setting up the child environment; the
  75  * "replace" variant overrides the value of any existing variable with that
  76  * "key". The "append" variant puts our new value at the end of a list,
  77  * separated by PATH_SEP (which is what separate values in
  78  * GIT_ALTERNATE_OBJECT_DIRECTORIES).
  79  */
  80 static void env_append(struct argv_array *env, const char *key, const char *val)
  81 {
  82         const char *old = getenv(key);
  83
  84         if (!old)
  85                 argv_array_pushf(env, "%s=%s", key, val);
  86         else
  87                 argv_array_pushf(env, "%s=%s%c%s", key, old, PATH_SEP, val);
  88 }
  89
  90 static void env_replace(struct argv_array *env, const char *key, const char *val)
  91 {
  92         argv_array_pushf(env, "%s=%s", key, val);
  93 }
  94
  95 static int setup_tmp_objdir(const char *root)
  96 {
  97         char *path;
  98         int ret = 0;
  99
 100         path = xstrfmt("%s/pack", root);
 101         ret = mkdir(path, 0777);
 102         free(path);
 103
 104         return ret;
 105 }
 106
 107 struct tmp_objdir *tmp_objdir_create(void)
 108 {
 109         static int installed_handlers;
 110         struct tmp_objdir *t;
 111
 112         if (the_tmp_objdir)
 113                 die("BUG: only one tmp_objdir can be used at a time");
 114
 115         t = xmalloc(sizeof(*t));
 116         strbuf_init(&t->path, 0);
 117         argv_array_init(&t->env);
 118
 119         strbuf_addf(&t->path, "%s/incoming-XXXXXX", get_object_directory());
 120
 121         /*
 122          * Grow the strbuf beyond any filename we expect to be placed in it.
 123          * If tmp_objdir_destroy() is called by a signal handler, then
 124          * we should be able to use the strbuf to remove files without
 125          * having to call malloc.
 126          */
 127         strbuf_grow(&t->path, 1024);
 128
 129         if (!mkdtemp(t->path.buf)) {
 130                 /* free, not destroy, as we never touched the filesystem */
 131                 tmp_objdir_free(t);
 132                 return NULL;
 133         }
 134
 135         the_tmp_objdir = t;
 136         if (!installed_handlers) {
 137                 atexit(remove_tmp_objdir);
 138                 sigchain_push_common(remove_tmp_objdir_on_signal);
 139                 installed_handlers++;
 140         }
 141
 142         if (setup_tmp_objdir(t->path.buf)) {
 143                 tmp_objdir_destroy(t);
 144                 return NULL;
 145         }
 146
 147         env_append(&t->env, ALTERNATE_DB_ENVIRONMENT,
 148                    absolute_path(get_object_directory()));
 149         env_replace(&t->env, DB_ENVIRONMENT, absolute_path(t->path.buf));
 150         env_replace(&t->env, GIT_QUARANTINE_ENVIRONMENT,
 151                     absolute_path(t->path.buf));
 152
 153         return t;
 154 }
 155
 156 /*
 157  * Make sure we copy packfiles and their associated metafiles in the correct
 158  * order. All of these ends_with checks are slightly expensive to do in
 159  * the midst of a sorting routine, but in practice it shouldn't matter.
 160  * We will have a relatively small number of packfiles to order, and loose
 161  * objects exit early in the first line.
 162  */
 163 static int pack_copy_priority(const char *name)
 164 {
 165         if (!starts_with(name, "pack"))
 166                 return 0;
 167         if (ends_with(name, ".keep"))
 168                 return 1;
 169         if (ends_with(name, ".pack"))
 170                 return 2;
 171         if (ends_with(name, ".idx"))
 172                 return 3;
 173         return 4;
 174 }
 175
 176 static int pack_copy_cmp(const char *a, const char *b)
 177 {
 178         return pack_copy_priority(a) - pack_copy_priority(b);
 179 }
 180
 181 static int read_dir_paths(struct string_list *out, const char *path)
 182 {
 183         DIR *dh;
 184         struct dirent *de;
 185
 186         dh = opendir(path);
 187         if (!dh)
 188                 return -1;
 189
 190         while ((de = readdir(dh)))
 191                 if (de->d_name[0] != '.')
 192                         string_list_append(out, de->d_name);
 193
 194         closedir(dh);
 195         return 0;
 196 }
 197
 198 static int migrate_paths(struct strbuf *src, struct strbuf *dst);
 199
 200 static int migrate_one(struct strbuf *src, struct strbuf *dst)
 201 {
 202         struct stat st;
 203
 204         if (stat(src->buf, &st) < 0)
 205                 return -1;
 206         if (S_ISDIR(st.st_mode)) {
 207                 if (!mkdir(dst->buf, 0777)) {
 208                         if (adjust_shared_perm(dst->buf))
 209                                 return -1;
 210                 } else if (errno != EEXIST)
 211                         return -1;
 212                 return migrate_paths(src, dst);
 213         }
 214         return finalize_object_file(src->buf, dst->buf);
 215 }
 216
 217 static int migrate_paths(struct strbuf *src, struct strbuf *dst)
 218 {
 219         size_t src_len = src->len, dst_len = dst->len;
 220         struct string_list paths = STRING_LIST_INIT_DUP;
 221         int i;
 222         int ret = 0;
 223
 224         if (read_dir_paths(&paths, src->buf) < 0)
 225                 return -1;
 226         paths.cmp = pack_copy_cmp;
 227         string_list_sort(&paths);
 228
 229         for (i = 0; i < paths.nr; i++) {
 230                 const char *name = paths.items[i].string;
 231
 232                 strbuf_addf(src, "/%s", name);
 233                 strbuf_addf(dst, "/%s", name);
 234
 235                 ret |= migrate_one(src, dst);
 236
 237                 strbuf_setlen(src, src_len);
 238                 strbuf_setlen(dst, dst_len);
 239         }
 240
 241         string_list_clear(&paths, 0);
 242         return ret;
 243 }
 244
 245 int tmp_objdir_migrate(struct tmp_objdir *t)
 246 {
 247         struct strbuf src = STRBUF_INIT, dst = STRBUF_INIT;
 248         int ret;
 249
 250         if (!t)
 251                 return 0;
 252
 253         strbuf_addbuf(&src, &t->path);
 254         strbuf_addstr(&dst, get_object_directory());
 255
 256         ret = migrate_paths(&src, &dst);
 257
 258         strbuf_release(&src);
 259         strbuf_release(&dst);
 260
 261         tmp_objdir_destroy(t);
 262         return ret;
 263 }
 264
 265 const char **tmp_objdir_env(const struct tmp_objdir *t)
 266 {
 267         if (!t)
 268                 return NULL;
 269         return t->env.argv;
 270 }
 271
 272 void tmp_objdir_add_as_alternate(const struct tmp_objdir *t)
 273 {
 274         add_to_alternates_memory(t->path.buf);
 275 }