server-info.c

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