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 #include "quote.h"
   9
  10 struct tmp_objdir {
  11         struct strbuf path;
  12         struct argv_array env;
  13 };
  14
  15 /*
  16  * Allow only one tmp_objdir at a time in a running process, which simplifies
  17  * our signal/atexit cleanup routines.  It's doubtful callers will ever need
  18  * more than one, and we can expand later if so.  You can have many such
  19  * tmp_objdirs simultaneously in many processes, of course.
  20  */
  21 static struct tmp_objdir *the_tmp_objdir;
  22
  23 static void tmp_objdir_free(struct tmp_objdir *t)
  24 {
  25         strbuf_release(&t->path);
  26         argv_array_clear(&t->env);
  27         free(t);
  28 }
  29
  30 static int tmp_objdir_destroy_1(struct tmp_objdir *t, int on_signal)
  31 {
  32         int err;
  33
  34         if (!t)
  35                 return 0;
  36
  37         if (t == the_tmp_objdir)
  38                 the_tmp_objdir = NULL;
  39
  40         /*
  41          * This may use malloc via strbuf_grow(), but we should
  42          * have pre-grown t->path sufficiently so that this
  43          * doesn't happen in practice.
  44          */
  45         err = remove_dir_recursively(&t->path, 0);
  46
  47         /*
  48          * When we are cleaning up due to a signal, we won't bother
  49          * freeing memory; it may cause a deadlock if the signal
  50          * arrived while libc's allocator lock is held.
  51          */
  52         if (!on_signal)
  53                 tmp_objdir_free(t);
  54         return err;
  55 }
  56
  57 int tmp_objdir_destroy(struct tmp_objdir *t)
  58 {
  59         return tmp_objdir_destroy_1(t, 0);
  60 }
  61
  62 static void remove_tmp_objdir(void)
  63 {
  64         tmp_objdir_destroy(the_tmp_objdir);
  65 }
  66
  67 static void remove_tmp_objdir_on_signal(int signo)
  68 {
  69         tmp_objdir_destroy_1(the_tmp_objdir, 1);
  70         sigchain_pop(signo);
  71         raise(signo);
  72 }
  73
  74 /*
  75  * These env_* functions are for setting up the child environment; the
  76  * "replace" variant overrides the value of any existing variable with that
  77  * "key". The "append" variant puts our new value at the end of a list,
  78  * separated by PATH_SEP (which is what separate values in
  79  * GIT_ALTERNATE_OBJECT_DIRECTORIES).
  80  */
  81 static void env_append(struct argv_array *env, const char *key, const char *val)
  82 {
  83         struct strbuf quoted = STRBUF_INIT;
  84         const char *old;
  85
  86         /*
  87          * Avoid quoting if it's not necessary, for maximum compatibility
  88          * with older parsers which don't understand the quoting.
  89          */
  90         if (*val == '"' || strchr(val, PATH_SEP)) {
  91                 strbuf_addch(&quoted, '"');
  92                 quote_c_style(val, &quoted, NULL, 1);
  93                 strbuf_addch(&quoted, '"');
  94                 val = quoted.buf;
  95         }
  96
  97         old = getenv(key);
  98         if (!old)
  99                 argv_array_pushf(env, "%s=%s", key, val);
 100         else
 101                 argv_array_pushf(env, "%s=%s%c%s", key, old, PATH_SEP, val);
 102
 103         strbuf_release(&quoted);
 104 }
 105
 106 static void env_replace(struct argv_array *env, const char *key, const char *val)
 107 {
 108         argv_array_pushf(env, "%s=%s", key, val);
 109 }
 110
 111 static int setup_tmp_objdir(const char *root)
 112 {
 113         char *path;
 114         int ret = 0;
 115
 116         path = xstrfmt("%s/pack", root);
 117         ret = mkdir(path, 0777);
 118         free(path);
 119
 120         return ret;
 121 }
 122
 123 struct tmp_objdir *tmp_objdir_create(void)
 124 {
 125         static int installed_handlers;
 126         struct tmp_objdir *t;
 127
 128         if (the_tmp_objdir)
 129                 die("BUG: only one tmp_objdir can be used at a time");
 130
 131         t = xmalloc(sizeof(*t));
 132         strbuf_init(&t->path, 0);
 133         argv_array_init(&t->env);
 134
 135         strbuf_addf(&t->path, "%s/incoming-XXXXXX", get_object_directory());
 136
 137         /*
 138          * Grow the strbuf beyond any filename we expect to be placed in it.
 139          * If tmp_objdir_destroy() is called by a signal handler, then
 140          * we should be able to use the strbuf to remove files without
 141          * having to call malloc.
 142          */
 143         strbuf_grow(&t->path, 1024);
 144
 145         if (!mkdtemp(t->path.buf)) {
 146                 /* free, not destroy, as we never touched the filesystem */
 147                 tmp_objdir_free(t);
 148                 return NULL;
 149         }
 150
 151         the_tmp_objdir = t;
 152         if (!installed_handlers) {
 153                 atexit(remove_tmp_objdir);
 154                 sigchain_push_common(remove_tmp_objdir_on_signal);
 155                 installed_handlers++;
 156         }
 157
 158         if (setup_tmp_objdir(t->path.buf)) {
 159                 tmp_objdir_destroy(t);
 160                 return NULL;
 161         }
 162
 163         env_append(&t->env, ALTERNATE_DB_ENVIRONMENT,
 164                    absolute_path(get_object_directory()));
 165         env_replace(&t->env, DB_ENVIRONMENT, absolute_path(t->path.buf));
 166         env_replace(&t->env, GIT_QUARANTINE_ENVIRONMENT,
 167                     absolute_path(t->path.buf));
 168
 169         return t;
 170 }
 171
 172 /*
 173  * Make sure we copy packfiles and their associated metafiles in the correct
 174  * order. All of these ends_with checks are slightly expensive to do in
 175  * the midst of a sorting routine, but in practice it shouldn't matter.
 176  * We will have a relatively small number of packfiles to order, and loose
 177  * objects exit early in the first line.
 178  */
 179 static int pack_copy_priority(const char *name)
 180 {
 181         if (!starts_with(name, "pack"))
 182                 return 0;
 183         if (ends_with(name, ".keep"))
 184                 return 1;
 185         if (ends_with(name, ".pack"))
 186                 return 2;
 187         if (ends_with(name, ".idx"))
 188                 return 3;
 189         return 4;
 190 }
 191
 192 static int pack_copy_cmp(const char *a, const char *b)
 193 {
 194         return pack_copy_priority(a) - pack_copy_priority(b);
 195 }
 196
 197 static int read_dir_paths(struct string_list *out, const char *path)
 198 {
 199         DIR *dh;
 200         struct dirent *de;
 201
 202         dh = opendir(path);
 203         if (!dh)
 204                 return -1;
 205
 206         while ((de = readdir(dh)))
 207                 if (de->d_name[0] != '.')
 208                         string_list_append(out, de->d_name);
 209
 210         closedir(dh);
 211         return 0;
 212 }
 213
 214 static int migrate_paths(struct strbuf *src, struct strbuf *dst);
 215
 216 static int migrate_one(struct strbuf *src, struct strbuf *dst)
 217 {
 218         struct stat st;
 219
 220         if (stat(src->buf, &st) < 0)
 221                 return -1;
 222         if (S_ISDIR(st.st_mode)) {
 223                 if (!mkdir(dst->buf, 0777)) {
 224                         if (adjust_shared_perm(dst->buf))
 225                                 return -1;
 226                 } else if (errno != EEXIST)
 227                         return -1;
 228                 return migrate_paths(src, dst);
 229         }
 230         return finalize_object_file(src->buf, dst->buf);
 231 }
 232
 233 static int migrate_paths(struct strbuf *src, struct strbuf *dst)
 234 {
 235         size_t src_len = src->len, dst_len = dst->len;
 236         struct string_list paths = STRING_LIST_INIT_DUP;
 237         int i;
 238         int ret = 0;
 239
 240         if (read_dir_paths(&paths, src->buf) < 0)
 241                 return -1;
 242         paths.cmp = pack_copy_cmp;
 243         string_list_sort(&paths);
 244
 245         for (i = 0; i < paths.nr; i++) {
 246                 const char *name = paths.items[i].string;
 247
 248                 strbuf_addf(src, "/%s", name);
 249                 strbuf_addf(dst, "/%s", name);
 250
 251                 ret |= migrate_one(src, dst);
 252
 253                 strbuf_setlen(src, src_len);
 254                 strbuf_setlen(dst, dst_len);
 255         }
 256
 257         string_list_clear(&paths, 0);
 258         return ret;
 259 }
 260
 261 int tmp_objdir_migrate(struct tmp_objdir *t)
 262 {
 263         struct strbuf src = STRBUF_INIT, dst = STRBUF_INIT;
 264         int ret;
 265
 266         if (!t)
 267                 return 0;
 268
 269         strbuf_addbuf(&src, &t->path);
 270         strbuf_addstr(&dst, get_object_directory());
 271
 272         ret = migrate_paths(&src, &dst);
 273
 274         strbuf_release(&src);
 275         strbuf_release(&dst);
 276
 277         tmp_objdir_destroy(t);
 278         return ret;
 279 }
 280
 281 const char **tmp_objdir_env(const struct tmp_objdir *t)
 282 {
 283         if (!t)
 284                 return NULL;
 285         return t->env.argv;
 286 }
 287
 288 void tmp_objdir_add_as_alternate(const struct tmp_objdir *t)
 289 {
 290         add_to_alternates_memory(t->path.buf);
 291 }