server-info.c

   1 #define DISABLE_SIGN_COMPARE_WARNINGS
   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 "odb.h"
  15 #include "server-info.h"
  16 #include "strbuf.h"
  17 #include "tempfile.h"
  18
  19 struct update_info_ctx {
  20         struct repository *repo;
  21         FILE *cur_fp;
  22         FILE *old_fp; /* becomes NULL if it differs from cur_fp */
  23         struct strbuf cur_sb;
  24         struct strbuf old_sb;
  25 };
  26
  27 static void uic_mark_stale(struct update_info_ctx *uic)
  28 {
  29         fclose(uic->old_fp);
  30         uic->old_fp = NULL;
  31 }
  32
  33 static int uic_is_stale(const struct update_info_ctx *uic)
  34 {
  35         return uic->old_fp == NULL;
  36 }
  37
  38 __attribute__((format (printf, 2, 3)))
  39 static int uic_printf(struct update_info_ctx *uic, const char *fmt, ...)
  40 {
  41         va_list ap;
  42         int ret = -1;
  43
  44         va_start(ap, fmt);
  45
  46         if (uic_is_stale(uic)) {
  47                 ret = vfprintf(uic->cur_fp, fmt, ap);
  48         } else {
  49                 ssize_t r;
  50                 struct strbuf *cur = &uic->cur_sb;
  51                 struct strbuf *old = &uic->old_sb;
  52
  53                 strbuf_reset(cur);
  54                 strbuf_vinsertf(cur, 0, fmt, ap);
  55
  56                 strbuf_reset(old);
  57                 strbuf_grow(old, cur->len);
  58                 r = fread(old->buf, 1, cur->len, uic->old_fp);
  59                 if (r != cur->len || memcmp(old->buf, cur->buf, r))
  60                         uic_mark_stale(uic);
  61
  62                 if (fwrite(cur->buf, 1, cur->len, uic->cur_fp) == cur->len)
  63                         ret = 0;
  64         }
  65
  66         va_end(ap);
  67
  68         return ret;
  69 }
  70
  71 /*
  72  * Create the file "path" by writing to a temporary file and renaming
  73  * it into place. The contents of the file come from "generate", which
  74  * should return non-zero if it encounters an error.
  75  */
  76 static int update_info_file(struct repository *r, char *path,
  77                         int (*generate)(struct update_info_ctx *),
  78                         int force)
  79 {
  80         char *tmp = mkpathdup("%s_XXXXXX", path);
  81         struct tempfile *f = NULL;
  82         int ret = -1;
  83         struct update_info_ctx uic = {
  84                 .repo = r,
  85                 .cur_fp = NULL,
  86                 .old_fp = NULL,
  87                 .cur_sb = STRBUF_INIT,
  88                 .old_sb = STRBUF_INIT
  89         };
  90
  91         safe_create_leading_directories(r, path);
  92         f = mks_tempfile_m(tmp, 0666);
  93         if (!f)
  94                 goto out;
  95         uic.cur_fp = fdopen_tempfile(f, "w");
  96         if (!uic.cur_fp)
  97                 goto out;
  98
  99         /* no problem on ENOENT and old_fp == NULL, it's stale, now */
 100         if (!force)
 101                 uic.old_fp = fopen_or_warn(path, "r");
 102
 103         /*
 104          * uic_printf will compare incremental comparison against old_fp
 105          * and mark uic as stale if needed
 106          */
 107         ret = generate(&uic);
 108         if (ret)
 109                 goto out;
 110
 111         /* new file may be shorter than the old one, check here */
 112         if (!uic_is_stale(&uic)) {
 113                 struct stat st;
 114                 long new_len = ftell(uic.cur_fp);
 115                 int old_fd = fileno(uic.old_fp);
 116
 117                 if (new_len < 0) {
 118                         ret = -1;
 119                         goto out;
 120                 }
 121                 if (fstat(old_fd, &st) || (st.st_size != (size_t)new_len))
 122                         uic_mark_stale(&uic);
 123         }
 124
 125         uic.cur_fp = NULL;
 126
 127         if (uic_is_stale(&uic)) {
 128                 if (adjust_shared_perm(r, get_tempfile_path(f)) < 0)
 129                         goto out;
 130                 if (rename_tempfile(&f, path) < 0)
 131                         goto out;
 132         } else {
 133                 delete_tempfile(&f);
 134         }
 135         ret = 0;
 136
 137 out:
 138         if (ret) {
 139                 error_errno("unable to update %s", path);
 140                 if (f)
 141                         delete_tempfile(&f);
 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 char *referent UNUSED, 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(uic->repo, 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(uic->repo, 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 refs_for_each_ref(get_main_ref_store(uic->repo),
 176                                  add_info_ref, uic);
 177 }
 178
 179 static int update_info_refs(struct repository *r, int force)
 180 {
 181         char *path = repo_git_path(r, "info/refs");
 182         int ret = update_info_file(r, path, generate_info_refs, force);
 183         free(path);
 184         return ret;
 185 }
 186
 187 /* packs */
 188 static struct pack_info {
 189         struct packed_git *p;
 190         int old_num;
 191         int new_num;
 192 } **info;
 193 static int num_pack;
 194
 195 static struct pack_info *find_pack_by_name(const char *name)
 196 {
 197         int i;
 198         for (i = 0; i < num_pack; i++) {
 199                 struct packed_git *p = info[i]->p;
 200                 if (!strcmp(pack_basename(p), name))
 201                         return info[i];
 202         }
 203         return NULL;
 204 }
 205
 206 /* Returns non-zero when we detect that the info in the
 207  * old file is useless.
 208  */
 209 static int parse_pack_def(const char *packname, int old_cnt)
 210 {
 211         struct pack_info *i = find_pack_by_name(packname);
 212         if (i) {
 213                 i->old_num = old_cnt;
 214                 return 0;
 215         }
 216         else {
 217                 /* The file describes a pack that is no longer here */
 218                 return 1;
 219         }
 220 }
 221
 222 /* Returns non-zero when we detect that the info in the
 223  * old file is useless.
 224  */
 225 static int read_pack_info_file(const char *infofile)
 226 {
 227         FILE *fp;
 228         struct strbuf line = STRBUF_INIT;
 229         int old_cnt = 0;
 230         int stale = 1;
 231
 232         fp = fopen_or_warn(infofile, "r");
 233         if (!fp)
 234                 return 1; /* nonexistent is not an error. */
 235
 236         while (strbuf_getline(&line, fp) != EOF) {
 237                 const char *arg;
 238
 239                 if (!line.len)
 240                         continue;
 241
 242                 if (skip_prefix(line.buf, "P ", &arg)) {
 243                         /* P name */
 244                         if (parse_pack_def(arg, old_cnt++))
 245                                 goto out_stale;
 246                 } else if (line.buf[0] == 'D') {
 247                         /* we used to emit D but that was misguided. */
 248                         goto out_stale;
 249                 } else if (line.buf[0] == 'T') {
 250                         /* we used to emit T but nobody uses it. */
 251                         goto out_stale;
 252                 } else {
 253                         error("unrecognized: %s", line.buf);
 254                 }
 255         }
 256         stale = 0;
 257
 258  out_stale:
 259         strbuf_release(&line);
 260         fclose(fp);
 261         return stale;
 262 }
 263
 264 static int compare_info(const void *a_, const void *b_)
 265 {
 266         struct pack_info *const *a = a_;
 267         struct pack_info *const *b = b_;
 268
 269         if (0 <= (*a)->old_num && 0 <= (*b)->old_num)
 270                 /* Keep the order in the original */
 271                 return (*a)->old_num - (*b)->old_num;
 272         else if (0 <= (*a)->old_num)
 273                 /* Only A existed in the original so B is obviously newer */
 274                 return -1;
 275         else if (0 <= (*b)->old_num)
 276                 /* The other way around. */
 277                 return 1;
 278
 279         /* then it does not matter but at least keep the comparison stable */
 280         if ((*a)->p == (*b)->p)
 281                 return 0;
 282         else if ((*a)->p < (*b)->p)
 283                 return -1;
 284         else
 285                 return 1;
 286 }
 287
 288 static void init_pack_info(struct repository *r, const char *infofile, int force)
 289 {
 290         struct packed_git *p;
 291         int stale;
 292         int i;
 293         size_t alloc = 0;
 294
 295         for (p = get_all_packs(r); p; p = p->next) {
 296                 /* we ignore things on alternate path since they are
 297                  * not available to the pullers in general.
 298                  */
 299                 if (!p->pack_local || !file_exists(p->pack_name))
 300                         continue;
 301
 302                 i = num_pack++;
 303                 ALLOC_GROW(info, num_pack, alloc);
 304                 CALLOC_ARRAY(info[i], 1);
 305                 info[i]->p = p;
 306                 info[i]->old_num = -1;
 307         }
 308
 309         if (infofile && !force)
 310                 stale = read_pack_info_file(infofile);
 311         else
 312                 stale = 1;
 313
 314         for (i = 0; i < num_pack; i++)
 315                 if (stale)
 316                         info[i]->old_num = -1;
 317
 318         /* renumber them */
 319         QSORT(info, num_pack, compare_info);
 320         for (i = 0; i < num_pack; i++)
 321                 info[i]->new_num = i;
 322 }
 323
 324 static void free_pack_info(void)
 325 {
 326         int i;
 327         for (i = 0; i < num_pack; i++)
 328                 free(info[i]);
 329         free(info);
 330 }
 331
 332 static int write_pack_info_file(struct update_info_ctx *uic)
 333 {
 334         int i;
 335         for (i = 0; i < num_pack; i++) {
 336                 if (uic_printf(uic, "P %s\n", pack_basename(info[i]->p)) < 0)
 337                         return -1;
 338         }
 339         if (uic_printf(uic, "\n") < 0)
 340                 return -1;
 341         return 0;
 342 }
 343
 344 static int update_info_packs(struct repository *r, int force)
 345 {
 346         char *infofile = mkpathdup("%s/info/packs",
 347                                    repo_get_object_directory(r));
 348         int ret;
 349
 350         init_pack_info(r, infofile, force);
 351         ret = update_info_file(r, infofile, write_pack_info_file, force);
 352         free_pack_info();
 353         free(infofile);
 354         return ret;
 355 }
 356
 357 /* public */
 358 int update_server_info(struct repository *r, int force)
 359 {
 360         /* We would add more dumb-server support files later,
 361          * including index of available pack files and their
 362          * intended audiences.
 363          */
 364         int errs = 0;
 365         char *path;
 366
 367         errs = errs | update_info_refs(r, force);
 368         errs = errs | update_info_packs(r, force);
 369
 370         /* remove leftover rev-cache file if there is any */
 371         path = repo_git_path(r, "info/rev-cache");
 372         unlink_or_warn(path);
 373         free(path);
 374
 375         return errs;
 376 }