server-info.c

   1 #define USE_THE_REPOSITORY_VARIABLE
   2
   3 #include "git-compat-util.h"
   4 #include "dir.h"
   5 #include "hex.h"
   6 #include "repository.h"
   7 #include "refs.h"
   8 #include "object.h"
   9 #include "commit.h"
  10 #include "tag.h"
  11 #include "packfile.h"
  12 #include "path.h"
  13 #include "object-file.h"
  14 #include "object-store-ll.h"
  15 #include "server-info.h"
  16 #include "strbuf.h"
  17 #include "tempfile.h"
  18
  19 struct update_info_ctx {
  20         FILE *cur_fp;
  21         FILE *old_fp; /* becomes NULL if it differs from cur_fp */
  22         struct strbuf cur_sb;
  23         struct strbuf old_sb;
  24 };
  25
  26 static void uic_mark_stale(struct update_info_ctx *uic)
  27 {
  28         fclose(uic->old_fp);
  29         uic->old_fp = NULL;
  30 }
  31
  32 static int uic_is_stale(const struct update_info_ctx *uic)
  33 {
  34         return uic->old_fp == NULL;
  35 }
  36
  37 __attribute__((format (printf, 2, 3)))
  38 static int uic_printf(struct update_info_ctx *uic, const char *fmt, ...)
  39 {
  40         va_list ap;
  41         int ret = -1;
  42
  43         va_start(ap, fmt);
  44
  45         if (uic_is_stale(uic)) {
  46                 ret = vfprintf(uic->cur_fp, fmt, ap);
  47         } else {
  48                 ssize_t r;
  49                 struct strbuf *cur = &uic->cur_sb;
  50                 struct strbuf *old = &uic->old_sb;
  51
  52                 strbuf_reset(cur);
  53                 strbuf_vinsertf(cur, 0, fmt, ap);
  54
  55                 strbuf_reset(old);
  56                 strbuf_grow(old, cur->len);
  57                 r = fread(old->buf, 1, cur->len, uic->old_fp);
  58                 if (r != cur->len || memcmp(old->buf, cur->buf, r))
  59                         uic_mark_stale(uic);
  60
  61                 if (fwrite(cur->buf, 1, cur->len, uic->cur_fp) == cur->len)
  62                         ret = 0;
  63         }
  64
  65         va_end(ap);
  66
  67         return ret;
  68 }
  69
  70 /*
  71  * Create the file "path" by writing to a temporary file and renaming
  72  * it into place. The contents of the file come from "generate", which
  73  * should return non-zero if it encounters an error.
  74  */
  75 static int update_info_file(char *path,
  76                         int (*generate)(struct update_info_ctx *),
  77                         int force)
  78 {
  79         char *tmp = mkpathdup("%s_XXXXXX", path);
  80         struct tempfile *f = NULL;
  81         int ret = -1;
  82         struct update_info_ctx uic = {
  83                 .cur_fp = NULL,
  84                 .old_fp = NULL,
  85                 .cur_sb = STRBUF_INIT,
  86                 .old_sb = STRBUF_INIT
  87         };
  88
  89         safe_create_leading_directories(path);
  90         f = mks_tempfile_m(tmp, 0666);
  91         if (!f)
  92                 goto out;
  93         uic.cur_fp = fdopen_tempfile(f, "w");
  94         if (!uic.cur_fp)
  95                 goto out;
  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
 125         if (uic_is_stale(&uic)) {
 126                 if (adjust_shared_perm(get_tempfile_path(f)) < 0)
 127                         goto out;
 128                 if (rename_tempfile(&f, path) < 0)
 129                         goto out;
 130         } else {
 131                 delete_tempfile(&f);
 132         }
 133         ret = 0;
 134
 135 out:
 136         if (ret) {
 137                 error_errno("unable to update %s", path);
 138                 if (f)
 139                         delete_tempfile(&f);
 140         }
 141         free(tmp);
 142         if (uic.old_fp)
 143                 fclose(uic.old_fp);
 144         strbuf_release(&uic.old_sb);
 145         strbuf_release(&uic.cur_sb);
 146         return ret;
 147 }
 148
 149 static int add_info_ref(const char *path, const char *referent UNUSED, const struct object_id *oid,
 150                         int flag UNUSED,
 151                         void *cb_data)
 152 {
 153         struct update_info_ctx *uic = cb_data;
 154         struct object *o = parse_object(the_repository, oid);
 155         if (!o)
 156                 return -1;
 157
 158         if (uic_printf(uic, "%s %s\n", oid_to_hex(oid), path) < 0)
 159                 return -1;
 160
 161         if (o->type == OBJ_TAG) {
 162                 o = deref_tag(the_repository, o, path, 0);
 163                 if (o)
 164                         if (uic_printf(uic, "%s %s^{}\n",
 165                                 oid_to_hex(&o->oid), path) < 0)
 166                                 return -1;
 167         }
 168         return 0;
 169 }
 170
 171 static int generate_info_refs(struct update_info_ctx *uic)
 172 {
 173         return refs_for_each_ref(get_main_ref_store(the_repository),
 174                                  add_info_ref, uic);
 175 }
 176
 177 static int update_info_refs(int force)
 178 {
 179         char *path = git_pathdup("info/refs");
 180         int ret = update_info_file(path, generate_info_refs, force);
 181         free(path);
 182         return ret;
 183 }
 184
 185 /* packs */
 186 static struct pack_info {
 187         struct packed_git *p;
 188         int old_num;
 189         int new_num;
 190 } **info;
 191 static int num_pack;
 192
 193 static struct pack_info *find_pack_by_name(const char *name)
 194 {
 195         int i;
 196         for (i = 0; i < num_pack; i++) {
 197                 struct packed_git *p = info[i]->p;
 198                 if (!strcmp(pack_basename(p), name))
 199                         return info[i];
 200         }
 201         return NULL;
 202 }
 203
 204 /* Returns non-zero when we detect that the info in the
 205  * old file is useless.
 206  */
 207 static int parse_pack_def(const char *packname, int old_cnt)
 208 {
 209         struct pack_info *i = find_pack_by_name(packname);
 210         if (i) {
 211                 i->old_num = old_cnt;
 212                 return 0;
 213         }
 214         else {
 215                 /* The file describes a pack that is no longer here */
 216                 return 1;
 217         }
 218 }
 219
 220 /* Returns non-zero when we detect that the info in the
 221  * old file is useless.
 222  */
 223 static int read_pack_info_file(const char *infofile)
 224 {
 225         FILE *fp;
 226         struct strbuf line = STRBUF_INIT;
 227         int old_cnt = 0;
 228         int stale = 1;
 229
 230         fp = fopen_or_warn(infofile, "r");
 231         if (!fp)
 232                 return 1; /* nonexistent is not an error. */
 233
 234         while (strbuf_getline(&line, fp) != EOF) {
 235                 const char *arg;
 236
 237                 if (!line.len)
 238                         continue;
 239
 240                 if (skip_prefix(line.buf, "P ", &arg)) {
 241                         /* P name */
 242                         if (parse_pack_def(arg, old_cnt++))
 243                                 goto out_stale;
 244                 } else if (line.buf[0] == 'D') {
 245                         /* we used to emit D but that was misguided. */
 246                         goto out_stale;
 247                 } else if (line.buf[0] == 'T') {
 248                         /* we used to emit T but nobody uses it. */
 249                         goto out_stale;
 250                 } else {
 251                         error("unrecognized: %s", line.buf);
 252                 }
 253         }
 254         stale = 0;
 255
 256  out_stale:
 257         strbuf_release(&line);
 258         fclose(fp);
 259         return stale;
 260 }
 261
 262 static int compare_info(const void *a_, const void *b_)
 263 {
 264         struct pack_info *const *a = a_;
 265         struct pack_info *const *b = b_;
 266
 267         if (0 <= (*a)->old_num && 0 <= (*b)->old_num)
 268                 /* Keep the order in the original */
 269                 return (*a)->old_num - (*b)->old_num;
 270         else if (0 <= (*a)->old_num)
 271                 /* Only A existed in the original so B is obviously newer */
 272                 return -1;
 273         else if (0 <= (*b)->old_num)
 274                 /* The other way around. */
 275                 return 1;
 276
 277         /* then it does not matter but at least keep the comparison stable */
 278         if ((*a)->p == (*b)->p)
 279                 return 0;
 280         else if ((*a)->p < (*b)->p)
 281                 return -1;
 282         else
 283                 return 1;
 284 }
 285
 286 static void init_pack_info(const char *infofile, int force)
 287 {
 288         struct packed_git *p;
 289         int stale;
 290         int i;
 291         size_t alloc = 0;
 292
 293         for (p = get_all_packs(the_repository); p; p = p->next) {
 294                 /* we ignore things on alternate path since they are
 295                  * not available to the pullers in general.
 296                  */
 297                 if (!p->pack_local || !file_exists(p->pack_name))
 298                         continue;
 299
 300                 i = num_pack++;
 301                 ALLOC_GROW(info, num_pack, alloc);
 302                 CALLOC_ARRAY(info[i], 1);
 303                 info[i]->p = p;
 304                 info[i]->old_num = -1;
 305         }
 306
 307         if (infofile && !force)
 308                 stale = read_pack_info_file(infofile);
 309         else
 310                 stale = 1;
 311
 312         for (i = 0; i < num_pack; i++)
 313                 if (stale)
 314                         info[i]->old_num = -1;
 315
 316         /* renumber them */
 317         QSORT(info, num_pack, compare_info);
 318         for (i = 0; i < num_pack; i++)
 319                 info[i]->new_num = i;
 320 }
 321
 322 static void free_pack_info(void)
 323 {
 324         int i;
 325         for (i = 0; i < num_pack; i++)
 326                 free(info[i]);
 327         free(info);
 328 }
 329
 330 static int write_pack_info_file(struct update_info_ctx *uic)
 331 {
 332         int i;
 333         for (i = 0; i < num_pack; i++) {
 334                 if (uic_printf(uic, "P %s\n", pack_basename(info[i]->p)) < 0)
 335                         return -1;
 336         }
 337         if (uic_printf(uic, "\n") < 0)
 338                 return -1;
 339         return 0;
 340 }
 341
 342 static int update_info_packs(int force)
 343 {
 344         char *infofile = mkpathdup("%s/info/packs",
 345                                    repo_get_object_directory(the_repository));
 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 }