server-info.c

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