server-info.c

   1 #include "git-compat-util.h"
   2 #include "dir.h"
   3 #include "environment.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 "path.h"
  12 #include "object-file.h"
  13 #include "object-store-ll.h"
  14 #include "server-info.h"
  15 #include "strbuf.h"
  16
  17 struct update_info_ctx {
  18         FILE *cur_fp;
  19         FILE *old_fp; /* becomes NULL if it differs from cur_fp */
  20         struct strbuf cur_sb;
  21         struct strbuf old_sb;
  22 };
  23
  24 static void uic_mark_stale(struct update_info_ctx *uic)
  25 {
  26         fclose(uic->old_fp);
  27         uic->old_fp = NULL;
  28 }
  29
  30 static int uic_is_stale(const struct update_info_ctx *uic)
  31 {
  32         return uic->old_fp == NULL;
  33 }
  34
  35 __attribute__((format (printf, 2, 3)))
  36 static int uic_printf(struct update_info_ctx *uic, const char *fmt, ...)
  37 {
  38         va_list ap;
  39         int ret = -1;
  40
  41         va_start(ap, fmt);
  42
  43         if (uic_is_stale(uic)) {
  44                 ret = vfprintf(uic->cur_fp, fmt, ap);
  45         } else {
  46                 ssize_t r;
  47                 struct strbuf *cur = &uic->cur_sb;
  48                 struct strbuf *old = &uic->old_sb;
  49
  50                 strbuf_reset(cur);
  51                 strbuf_vinsertf(cur, 0, fmt, ap);
  52
  53                 strbuf_reset(old);
  54                 strbuf_grow(old, cur->len);
  55                 r = fread(old->buf, 1, cur->len, uic->old_fp);
  56                 if (r != cur->len || memcmp(old->buf, cur->buf, r))
  57                         uic_mark_stale(uic);
  58
  59                 if (fwrite(cur->buf, 1, cur->len, uic->cur_fp) == cur->len)
  60                         ret = 0;
  61         }
  62
  63         va_end(ap);
  64
  65         return ret;
  66 }
  67
  68 /*
  69  * Create the file "path" by writing to a temporary file and renaming
  70  * it into place. The contents of the file come from "generate", which
  71  * should return non-zero if it encounters an error.
  72  */
  73 static int update_info_file(char *path,
  74                         int (*generate)(struct update_info_ctx *),
  75                         int force)
  76 {
  77         char *tmp = mkpathdup("%s_XXXXXX", path);
  78         int ret = -1;
  79         int fd = -1;
  80         FILE *to_close;
  81         struct update_info_ctx uic = {
  82                 .cur_fp = NULL,
  83                 .old_fp = NULL,
  84                 .cur_sb = STRBUF_INIT,
  85                 .old_sb = STRBUF_INIT
  86         };
  87
  88         safe_create_leading_directories(path);
  89         fd = git_mkstemp_mode(tmp, 0666);
  90         if (fd < 0)
  91                 goto out;
  92         to_close = uic.cur_fp = fdopen(fd, "w");
  93         if (!uic.cur_fp)
  94                 goto out;
  95         fd = -1;
  96
  97         /* no problem on ENOENT and old_fp == NULL, it's stale, now */
  98         if (!force)
  99                 uic.old_fp = fopen_or_warn(path, "r");
 100
 101         /*
 102          * uic_printf will compare incremental comparison against old_fp
 103          * and mark uic as stale if needed
 104          */
 105         ret = generate(&uic);
 106         if (ret)
 107                 goto out;
 108
 109         /* new file may be shorter than the old one, check here */
 110         if (!uic_is_stale(&uic)) {
 111                 struct stat st;
 112                 long new_len = ftell(uic.cur_fp);
 113                 int old_fd = fileno(uic.old_fp);
 114
 115                 if (new_len < 0) {
 116                         ret = -1;
 117                         goto out;
 118                 }
 119                 if (fstat(old_fd, &st) || (st.st_size != (size_t)new_len))
 120                         uic_mark_stale(&uic);
 121         }
 122
 123         uic.cur_fp = NULL;
 124         if (fclose(to_close))
 125                 goto out;
 126
 127         if (uic_is_stale(&uic)) {
 128                 if (adjust_shared_perm(tmp) < 0)
 129                         goto out;
 130                 if (rename(tmp, path) < 0)
 131                         goto out;
 132         } else {
 133                 unlink(tmp);
 134         }
 135         ret = 0;
 136
 137 out:
 138         if (ret) {
 139                 error_errno("unable to update %s", path);
 140                 if (uic.cur_fp)
 141                         fclose(uic.cur_fp);
 142                 else if (fd >= 0)
 143                         close(fd);
 144                 unlink(tmp);
 145         }
 146         free(tmp);
 147         if (uic.old_fp)
 148                 fclose(uic.old_fp);
 149         strbuf_release(&uic.old_sb);
 150         strbuf_release(&uic.cur_sb);
 151         return ret;
 152 }
 153
 154 static int add_info_ref(const char *path, const struct object_id *oid,
 155                         int flag UNUSED,
 156                         void *cb_data)
 157 {
 158         struct update_info_ctx *uic = cb_data;
 159         struct object *o = parse_object(the_repository, oid);
 160         if (!o)
 161                 return -1;
 162
 163         if (uic_printf(uic, "%s %s\n", oid_to_hex(oid), path) < 0)
 164                 return -1;
 165
 166         if (o->type == OBJ_TAG) {
 167                 o = deref_tag(the_repository, o, path, 0);
 168                 if (o)
 169                         if (uic_printf(uic, "%s %s^{}\n",
 170                                 oid_to_hex(&o->oid), path) < 0)
 171                                 return -1;
 172         }
 173         return 0;
 174 }
 175
 176 static int generate_info_refs(struct update_info_ctx *uic)
 177 {
 178         return for_each_ref(add_info_ref, uic);
 179 }
 180
 181 static int update_info_refs(int force)
 182 {
 183         char *path = git_pathdup("info/refs");
 184         int ret = update_info_file(path, generate_info_refs, force);
 185         free(path);
 186         return ret;
 187 }
 188
 189 /* packs */
 190 static struct pack_info {
 191         struct packed_git *p;
 192         int old_num;
 193         int new_num;
 194 } **info;
 195 static int num_pack;
 196
 197 static struct pack_info *find_pack_by_name(const char *name)
 198 {
 199         int i;
 200         for (i = 0; i < num_pack; i++) {
 201                 struct packed_git *p = info[i]->p;
 202                 if (!strcmp(pack_basename(p), name))
 203                         return info[i];
 204         }
 205         return NULL;
 206 }
 207
 208 /* Returns non-zero when we detect that the info in the
 209  * old file is useless.
 210  */
 211 static int parse_pack_def(const char *packname, int old_cnt)
 212 {
 213         struct pack_info *i = find_pack_by_name(packname);
 214         if (i) {
 215                 i->old_num = old_cnt;
 216                 return 0;
 217         }
 218         else {
 219                 /* The file describes a pack that is no longer here */
 220                 return 1;
 221         }
 222 }
 223
 224 /* Returns non-zero when we detect that the info in the
 225  * old file is useless.
 226  */
 227 static int read_pack_info_file(const char *infofile)
 228 {
 229         FILE *fp;
 230         struct strbuf line = STRBUF_INIT;
 231         int old_cnt = 0;
 232         int stale = 1;
 233
 234         fp = fopen_or_warn(infofile, "r");
 235         if (!fp)
 236                 return 1; /* nonexistent is not an error. */
 237
 238         while (strbuf_getline(&line, fp) != EOF) {
 239                 const char *arg;
 240
 241                 if (!line.len)
 242                         continue;
 243
 244                 if (skip_prefix(line.buf, "P ", &arg)) {
 245                         /* P name */
 246                         if (parse_pack_def(arg, old_cnt++))
 247                                 goto out_stale;
 248                 } else if (line.buf[0] == 'D') {
 249                         /* we used to emit D but that was misguided. */
 250                         goto out_stale;
 251                 } else if (line.buf[0] == 'T') {
 252                         /* we used to emit T but nobody uses it. */
 253                         goto out_stale;
 254                 } else {
 255                         error("unrecognized: %s", line.buf);
 256                 }
 257         }
 258         stale = 0;
 259
 260  out_stale:
 261         strbuf_release(&line);
 262         fclose(fp);
 263         return stale;
 264 }
 265
 266 static int compare_info(const void *a_, const void *b_)
 267 {
 268         struct pack_info *const *a = a_;
 269         struct pack_info *const *b = b_;
 270
 271         if (0 <= (*a)->old_num && 0 <= (*b)->old_num)
 272                 /* Keep the order in the original */
 273                 return (*a)->old_num - (*b)->old_num;
 274         else if (0 <= (*a)->old_num)
 275                 /* Only A existed in the original so B is obviously newer */
 276                 return -1;
 277         else if (0 <= (*b)->old_num)
 278                 /* The other way around. */
 279                 return 1;
 280
 281         /* then it does not matter but at least keep the comparison stable */
 282         if ((*a)->p == (*b)->p)
 283                 return 0;
 284         else if ((*a)->p < (*b)->p)
 285                 return -1;
 286         else
 287                 return 1;
 288 }
 289
 290 static void init_pack_info(const char *infofile, int force)
 291 {
 292         struct packed_git *p;
 293         int stale;
 294         int i;
 295         size_t alloc = 0;
 296
 297         for (p = get_all_packs(the_repository); p; p = p->next) {
 298                 /* we ignore things on alternate path since they are
 299                  * not available to the pullers in general.
 300                  */
 301                 if (!p->pack_local || !file_exists(p->pack_name))
 302                         continue;
 303
 304                 i = num_pack++;
 305                 ALLOC_GROW(info, num_pack, alloc);
 306                 CALLOC_ARRAY(info[i], 1);
 307                 info[i]->p = p;
 308                 info[i]->old_num = -1;
 309         }
 310
 311         if (infofile && !force)
 312                 stale = read_pack_info_file(infofile);
 313         else
 314                 stale = 1;
 315
 316         for (i = 0; i < num_pack; i++)
 317                 if (stale)
 318                         info[i]->old_num = -1;
 319
 320         /* renumber them */
 321         QSORT(info, num_pack, compare_info);
 322         for (i = 0; i < num_pack; i++)
 323                 info[i]->new_num = i;
 324 }
 325
 326 static void free_pack_info(void)
 327 {
 328         int i;
 329         for (i = 0; i < num_pack; i++)
 330                 free(info[i]);
 331         free(info);
 332 }
 333
 334 static int write_pack_info_file(struct update_info_ctx *uic)
 335 {
 336         int i;
 337         for (i = 0; i < num_pack; i++) {
 338                 if (uic_printf(uic, "P %s\n", pack_basename(info[i]->p)) < 0)
 339                         return -1;
 340         }
 341         if (uic_printf(uic, "\n") < 0)
 342                 return -1;
 343         return 0;
 344 }
 345
 346 static int update_info_packs(int force)
 347 {
 348         char *infofile = mkpathdup("%s/info/packs", get_object_directory());
 349         int ret;
 350
 351         init_pack_info(infofile, force);
 352         ret = update_info_file(infofile, write_pack_info_file, force);
 353         free_pack_info();
 354         free(infofile);
 355         return ret;
 356 }
 357
 358 /* public */
 359 int update_server_info(int force)
 360 {
 361         /* We would add more dumb-server support files later,
 362          * including index of available pack files and their
 363          * intended audiences.
 364          */
 365         int errs = 0;
 366
 367         errs = errs | update_info_refs(force);
 368         errs = errs | update_info_packs(force);
 369
 370         /* remove leftover rev-cache file if there is any */
 371         unlink_or_warn(git_path("info/rev-cache"));
 372
 373         return errs;
 374 }