server-info.c

   1 #include "cache.h"
   2 #include "repository.h"
   3 #include "refs.h"
   4 #include "object.h"
   5 #include "commit.h"
   6 #include "tag.h"
   7 #include "packfile.h"
   8 #include "object-store.h"
   9 #include "strbuf.h"
  10
  11 struct update_info_ctx {
  12         FILE *cur_fp;
  13         FILE *old_fp; /* becomes NULL if it differs from cur_fp */
  14         struct strbuf cur_sb;
  15         struct strbuf old_sb;
  16 };
  17
  18 static void uic_mark_stale(struct update_info_ctx *uic)
  19 {
  20         fclose(uic->old_fp);
  21         uic->old_fp = NULL;
  22 }
  23
  24 static int uic_is_stale(const struct update_info_ctx *uic)
  25 {
  26         return uic->old_fp == NULL;
  27 }
  28
  29 static int uic_printf(struct update_info_ctx *uic, const char *fmt, ...)
  30 {
  31         va_list ap;
  32         int ret = -1;
  33
  34         va_start(ap, fmt);
  35
  36         if (uic_is_stale(uic)) {
  37                 ret = vfprintf(uic->cur_fp, fmt, ap);
  38         } else {
  39                 ssize_t r;
  40                 struct strbuf *cur = &uic->cur_sb;
  41                 struct strbuf *old = &uic->old_sb;
  42
  43                 strbuf_reset(cur);
  44                 strbuf_vinsertf(cur, 0, fmt, ap);
  45
  46                 strbuf_reset(old);
  47                 strbuf_grow(old, cur->len);
  48                 r = fread(old->buf, 1, cur->len, uic->old_fp);
  49                 if (r != cur->len || memcmp(old->buf, cur->buf, r))
  50                         uic_mark_stale(uic);
  51
  52                 if (fwrite(cur->buf, 1, cur->len, uic->cur_fp) == cur->len)
  53                         ret = 0;
  54         }
  55
  56         va_end(ap);
  57
  58         return ret;
  59 }
  60
  61 /*
  62  * Create the file "path" by writing to a temporary file and renaming
  63  * it into place. The contents of the file come from "generate", which
  64  * should return non-zero if it encounters an error.
  65  */
  66 static int update_info_file(char *path,
  67                         int (*generate)(struct update_info_ctx *),
  68                         int force)
  69 {
  70         char *tmp = mkpathdup("%s_XXXXXX", path);
  71         int ret = -1;
  72         int fd = -1;
  73         FILE *to_close;
  74         struct update_info_ctx uic = {
  75                 .cur_fp = NULL,
  76                 .old_fp = NULL,
  77                 .cur_sb = STRBUF_INIT,
  78                 .old_sb = STRBUF_INIT
  79         };
  80
  81         safe_create_leading_directories(path);
  82         fd = git_mkstemp_mode(tmp, 0666);
  83         if (fd < 0)
  84                 goto out;
  85         to_close = uic.cur_fp = fdopen(fd, "w");
  86         if (!uic.cur_fp)
  87                 goto out;
  88         fd = -1;
  89
  90         /* no problem on ENOENT and old_fp == NULL, it's stale, now */
  91         if (!force)
  92                 uic.old_fp = fopen_or_warn(path, "r");
  93
  94         /*
  95          * uic_printf will compare incremental comparison aginst old_fp
  96          * and mark uic as stale if needed
  97          */
  98         ret = generate(&uic);
  99         if (ret)
 100                 goto out;
 101
 102         /* new file may be shorter than the old one, check here */
 103         if (!uic_is_stale(&uic)) {
 104                 struct stat st;
 105                 long new_len = ftell(uic.cur_fp);
 106                 int old_fd = fileno(uic.old_fp);
 107
 108                 if (new_len < 0) {
 109                         ret = -1;
 110                         goto out;
 111                 }
 112                 if (fstat(old_fd, &st) || (st.st_size != (size_t)new_len))
 113                         uic_mark_stale(&uic);
 114         }
 115
 116         uic.cur_fp = NULL;
 117         if (fclose(to_close))
 118                 goto out;
 119
 120         if (uic_is_stale(&uic)) {
 121                 if (adjust_shared_perm(tmp) < 0)
 122                         goto out;
 123                 if (rename(tmp, path) < 0)
 124                         goto out;
 125         } else {
 126                 unlink(tmp);
 127         }
 128         ret = 0;
 129
 130 out:
 131         if (ret) {
 132                 error_errno("unable to update %s", path);
 133                 if (uic.cur_fp)
 134                         fclose(uic.cur_fp);
 135                 else if (fd >= 0)
 136                         close(fd);
 137                 unlink(tmp);
 138         }
 139         free(tmp);
 140         if (uic.old_fp)
 141                 fclose(uic.old_fp);
 142         strbuf_release(&uic.old_sb);
 143         strbuf_release(&uic.cur_sb);
 144         return ret;
 145 }
 146
 147 static int add_info_ref(const char *path, const struct object_id *oid,
 148                         int flag, void *cb_data)
 149 {
 150         struct update_info_ctx *uic = cb_data;
 151         struct object *o = parse_object(the_repository, oid);
 152         if (!o)
 153                 return -1;
 154
 155         if (uic_printf(uic, "%s %s\n", oid_to_hex(oid), path) < 0)
 156                 return -1;
 157
 158         if (o->type == OBJ_TAG) {
 159                 o = deref_tag(the_repository, o, path, 0);
 160                 if (o)
 161                         if (uic_printf(uic, "%s %s^{}\n",
 162                                 oid_to_hex(&o->oid), path) < 0)
 163                                 return -1;
 164         }
 165         return 0;
 166 }
 167
 168 static int generate_info_refs(struct update_info_ctx *uic)
 169 {
 170         return for_each_ref(add_info_ref, uic);
 171 }
 172
 173 static int update_info_refs(int force)
 174 {
 175         char *path = git_pathdup("info/refs");
 176         int ret = update_info_file(path, generate_info_refs, force);
 177         free(path);
 178         return ret;
 179 }
 180
 181 /* packs */
 182 static struct pack_info {
 183         struct packed_git *p;
 184         int old_num;
 185         int new_num;
 186 } **info;
 187 static int num_pack;
 188
 189 static struct pack_info *find_pack_by_name(const char *name)
 190 {
 191         int i;
 192         for (i = 0; i < num_pack; i++) {
 193                 struct packed_git *p = info[i]->p;
 194                 if (!strcmp(pack_basename(p), name))
 195                         return info[i];
 196         }
 197         return NULL;
 198 }
 199
 200 /* Returns non-zero when we detect that the info in the
 201  * old file is useless.
 202  */
 203 static int parse_pack_def(const char *packname, int old_cnt)
 204 {
 205         struct pack_info *i = find_pack_by_name(packname);
 206         if (i) {
 207                 i->old_num = old_cnt;
 208                 return 0;
 209         }
 210         else {
 211                 /* The file describes a pack that is no longer here */
 212                 return 1;
 213         }
 214 }
 215
 216 /* Returns non-zero when we detect that the info in the
 217  * old file is useless.
 218  */
 219 static int read_pack_info_file(const char *infofile)
 220 {
 221         FILE *fp;
 222         struct strbuf line = STRBUF_INIT;
 223         int old_cnt = 0;
 224         int stale = 1;
 225
 226         fp = fopen_or_warn(infofile, "r");
 227         if (!fp)
 228                 return 1; /* nonexistent is not an error. */
 229
 230         while (strbuf_getline(&line, fp) != EOF) {
 231                 const char *arg;
 232
 233                 if (!line.len)
 234                         continue;
 235
 236                 if (skip_prefix(line.buf, "P ", &arg)) {
 237                         /* P name */
 238                         if (parse_pack_def(arg, old_cnt++))
 239                                 goto out_stale;
 240                 } else if (line.buf[0] == 'D') {
 241                         /* we used to emit D but that was misguided. */
 242                         goto out_stale;
 243                 } else if (line.buf[0] == 'T') {
 244                         /* we used to emit T but nobody uses it. */
 245                         goto out_stale;
 246                 } else {
 247                         error("unrecognized: %s", line.buf);
 248                 }
 249         }
 250         stale = 0;
 251
 252  out_stale:
 253         strbuf_release(&line);
 254         fclose(fp);
 255         return stale;
 256 }
 257
 258 static int compare_info(const void *a_, const void *b_)
 259 {
 260         struct pack_info *const *a = a_;
 261         struct pack_info *const *b = b_;
 262
 263         if (0 <= (*a)->old_num && 0 <= (*b)->old_num)
 264                 /* Keep the order in the original */
 265                 return (*a)->old_num - (*b)->old_num;
 266         else if (0 <= (*a)->old_num)
 267                 /* Only A existed in the original so B is obviously newer */
 268                 return -1;
 269         else if (0 <= (*b)->old_num)
 270                 /* The other way around. */
 271                 return 1;
 272
 273         /* then it does not matter but at least keep the comparison stable */
 274         if ((*a)->p == (*b)->p)
 275                 return 0;
 276         else if ((*a)->p < (*b)->p)
 277                 return -1;
 278         else
 279                 return 1;
 280 }
 281
 282 static void init_pack_info(const char *infofile, int force)
 283 {
 284         struct packed_git *p;
 285         int stale;
 286         int i = 0;
 287
 288         for (p = get_all_packs(the_repository); p; p = p->next) {
 289                 /* we ignore things on alternate path since they are
 290                  * not available to the pullers in general.
 291                  */
 292                 if (!p->pack_local)
 293                         continue;
 294                 i++;
 295         }
 296         num_pack = i;
 297         info = xcalloc(num_pack, sizeof(struct pack_info *));
 298         for (i = 0, p = get_all_packs(the_repository); p; p = p->next) {
 299                 if (!p->pack_local)
 300                         continue;
 301                 assert(i < num_pack);
 302                 info[i] = xcalloc(1, sizeof(struct pack_info));
 303                 info[i]->p = p;
 304                 info[i]->old_num = -1;
 305                 i++;
 306         }
 307
 308         if (infofile && !force)
 309                 stale = read_pack_info_file(infofile);
 310         else
 311                 stale = 1;
 312
 313         for (i = 0; i < num_pack; i++)
 314                 if (stale)
 315                         info[i]->old_num = -1;
 316
 317         /* renumber them */
 318         QSORT(info, num_pack, compare_info);
 319         for (i = 0; i < num_pack; i++)
 320                 info[i]->new_num = i;
 321 }
 322
 323 static void free_pack_info(void)
 324 {
 325         int i;
 326         for (i = 0; i < num_pack; i++)
 327                 free(info[i]);
 328         free(info);
 329 }
 330
 331 static int write_pack_info_file(struct update_info_ctx *uic)
 332 {
 333         int i;
 334         for (i = 0; i < num_pack; i++) {
 335                 if (uic_printf(uic, "P %s\n", pack_basename(info[i]->p)) < 0)
 336                         return -1;
 337         }
 338         if (uic_printf(uic, "\n") < 0)
 339                 return -1;
 340         return 0;
 341 }
 342
 343 static int update_info_packs(int force)
 344 {
 345         char *infofile = mkpathdup("%s/info/packs", get_object_directory());
 346         int ret;
 347
 348         init_pack_info(infofile, force);
 349         ret = update_info_file(infofile, write_pack_info_file, force);
 350         free_pack_info();
 351         free(infofile);
 352         return ret;
 353 }
 354
 355 /* public */
 356 int update_server_info(int force)
 357 {
 358         /* We would add more dumb-server support files later,
 359          * including index of available pack files and their
 360          * intended audiences.
 361          */
 362         int errs = 0;
 363
 364         errs = errs | update_info_refs(force);
 365         errs = errs | update_info_packs(force);
 366
 367         /* remove leftover rev-cache file if there is any */
 368         unlink_or_warn(git_path("info/rev-cache"));
 369
 370         return errs;
 371 }