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