server-info.c

   1 #include "git-compat-util.h"
   2 #include "alloc.h"
   3 #include "dir.h"
   4 #include "environment.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 "object-file.h"
  13 #include "object-store.h"
  14 #include "server-info.h"
  15 #include "strbuf.h"
  16 #include "wrapper.h"
  17
  18 struct update_info_ctx {
  19         FILE *cur_fp;
  20         FILE *old_fp; /* becomes NULL if it differs from cur_fp */
  21         struct strbuf cur_sb;
  22         struct strbuf old_sb;
  23 };
  24
  25 static void uic_mark_stale(struct update_info_ctx *uic)
  26 {
  27         fclose(uic->old_fp);
  28         uic->old_fp = NULL;
  29 }
  30
  31 static int uic_is_stale(const struct update_info_ctx *uic)
  32 {
  33         return uic->old_fp == NULL;
  34 }
  35
  36 __attribute__((format (printf, 2, 3)))
  37 static int uic_printf(struct update_info_ctx *uic, const char *fmt, ...)
  38 {
  39         va_list ap;
  40         int ret = -1;
  41
  42         va_start(ap, fmt);
  43
  44         if (uic_is_stale(uic)) {
  45                 ret = vfprintf(uic->cur_fp, fmt, ap);
  46         } else {
  47                 ssize_t r;
  48                 struct strbuf *cur = &uic->cur_sb;
  49                 struct strbuf *old = &uic->old_sb;
  50
  51                 strbuf_reset(cur);
  52                 strbuf_vinsertf(cur, 0, fmt, ap);
  53
  54                 strbuf_reset(old);
  55                 strbuf_grow(old, cur->len);
  56                 r = fread(old->buf, 1, cur->len, uic->old_fp);
  57                 if (r != cur->len || memcmp(old->buf, cur->buf, r))
  58                         uic_mark_stale(uic);
  59
  60                 if (fwrite(cur->buf, 1, cur->len, uic->cur_fp) == cur->len)
  61                         ret = 0;
  62         }
  63
  64         va_end(ap);
  65
  66         return ret;
  67 }
  68
  69 /*
  70  * Create the file "path" by writing to a temporary file and renaming
  71  * it into place. The contents of the file come from "generate", which
  72  * should return non-zero if it encounters an error.
  73  */
  74 static int update_info_file(char *path,
  75                         int (*generate)(struct update_info_ctx *),
  76                         int force)
  77 {
  78         char *tmp = mkpathdup("%s_XXXXXX", path);
  79         int ret = -1;
  80         int fd = -1;
  81         FILE *to_close;
  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         fd = git_mkstemp_mode(tmp, 0666);
  91         if (fd < 0)
  92                 goto out;
  93         to_close = uic.cur_fp = fdopen(fd, "w");
  94         if (!uic.cur_fp)
  95                 goto out;
  96         fd = -1;
  97
  98         /* no problem on ENOENT and old_fp == NULL, it's stale, now */
  99         if (!force)
 100                 uic.old_fp = fopen_or_warn(path, "r");
 101
 102         /*
 103          * uic_printf will compare incremental comparison against old_fp
 104          * and mark uic as stale if needed
 105          */
 106         ret = generate(&uic);
 107         if (ret)
 108                 goto out;
 109
 110         /* new file may be shorter than the old one, check here */
 111         if (!uic_is_stale(&uic)) {
 112                 struct stat st;
 113                 long new_len = ftell(uic.cur_fp);
 114                 int old_fd = fileno(uic.old_fp);
 115
 116                 if (new_len < 0) {
 117                         ret = -1;
 118                         goto out;
 119                 }
 120                 if (fstat(old_fd, &st) || (st.st_size != (size_t)new_len))
 121                         uic_mark_stale(&uic);
 122         }
 123
 124         uic.cur_fp = NULL;
 125         if (fclose(to_close))
 126                 goto out;
 127
 128         if (uic_is_stale(&uic)) {
 129                 if (adjust_shared_perm(tmp) < 0)
 130                         goto out;
 131                 if (rename(tmp, path) < 0)
 132                         goto out;
 133         } else {
 134                 unlink(tmp);
 135         }
 136         ret = 0;
 137
 138 out:
 139         if (ret) {
 140                 error_errno("unable to update %s", path);
 141                 if (uic.cur_fp)
 142                         fclose(uic.cur_fp);
 143                 else if (fd >= 0)
 144                         close(fd);
 145                 unlink(tmp);
 146         }
 147         free(tmp);
 148         if (uic.old_fp)
 149                 fclose(uic.old_fp);
 150         strbuf_release(&uic.old_sb);
 151         strbuf_release(&uic.cur_sb);
 152         return ret;
 153 }
 154
 155 static int add_info_ref(const char *path, const struct object_id *oid,
 156                         int flag UNUSED,
 157                         void *cb_data)
 158 {
 159         struct update_info_ctx *uic = cb_data;
 160         struct object *o = parse_object(the_repository, oid);
 161         if (!o)
 162                 return -1;
 163
 164         if (uic_printf(uic, "%s %s\n", oid_to_hex(oid), path) < 0)
 165                 return -1;
 166
 167         if (o->type == OBJ_TAG) {
 168                 o = deref_tag(the_repository, o, path, 0);
 169                 if (o)
 170                         if (uic_printf(uic, "%s %s^{}\n",
 171                                 oid_to_hex(&o->oid), path) < 0)
 172                                 return -1;
 173         }
 174         return 0;
 175 }
 176
 177 static int generate_info_refs(struct update_info_ctx *uic)
 178 {
 179         return for_each_ref(add_info_ref, uic);
 180 }
 181
 182 static int update_info_refs(int force)
 183 {
 184         char *path = git_pathdup("info/refs");
 185         int ret = update_info_file(path, generate_info_refs, force);
 186         free(path);
 187         return ret;
 188 }
 189
 190 /* packs */
 191 static struct pack_info {
 192         struct packed_git *p;
 193         int old_num;
 194         int new_num;
 195 } **info;
 196 static int num_pack;
 197
 198 static struct pack_info *find_pack_by_name(const char *name)
 199 {
 200         int i;
 201         for (i = 0; i < num_pack; i++) {
 202                 struct packed_git *p = info[i]->p;
 203                 if (!strcmp(pack_basename(p), name))
 204                         return info[i];
 205         }
 206         return NULL;
 207 }
 208
 209 /* Returns non-zero when we detect that the info in the
 210  * old file is useless.
 211  */
 212 static int parse_pack_def(const char *packname, int old_cnt)
 213 {
 214         struct pack_info *i = find_pack_by_name(packname);
 215         if (i) {
 216                 i->old_num = old_cnt;
 217                 return 0;
 218         }
 219         else {
 220                 /* The file describes a pack that is no longer here */
 221                 return 1;
 222         }
 223 }
 224
 225 /* Returns non-zero when we detect that the info in the
 226  * old file is useless.
 227  */
 228 static int read_pack_info_file(const char *infofile)
 229 {
 230         FILE *fp;
 231         struct strbuf line = STRBUF_INIT;
 232         int old_cnt = 0;
 233         int stale = 1;
 234
 235         fp = fopen_or_warn(infofile, "r");
 236         if (!fp)
 237                 return 1; /* nonexistent is not an error. */
 238
 239         while (strbuf_getline(&line, fp) != EOF) {
 240                 const char *arg;
 241
 242                 if (!line.len)
 243                         continue;
 244
 245                 if (skip_prefix(line.buf, "P ", &arg)) {
 246                         /* P name */
 247                         if (parse_pack_def(arg, old_cnt++))
 248                                 goto out_stale;
 249                 } else if (line.buf[0] == 'D') {
 250                         /* we used to emit D but that was misguided. */
 251                         goto out_stale;
 252                 } else if (line.buf[0] == 'T') {
 253                         /* we used to emit T but nobody uses it. */
 254                         goto out_stale;
 255                 } else {
 256                         error("unrecognized: %s", line.buf);
 257                 }
 258         }
 259         stale = 0;
 260
 261  out_stale:
 262         strbuf_release(&line);
 263         fclose(fp);
 264         return stale;
 265 }
 266
 267 static int compare_info(const void *a_, const void *b_)
 268 {
 269         struct pack_info *const *a = a_;
 270         struct pack_info *const *b = b_;
 271
 272         if (0 <= (*a)->old_num && 0 <= (*b)->old_num)
 273                 /* Keep the order in the original */
 274                 return (*a)->old_num - (*b)->old_num;
 275         else if (0 <= (*a)->old_num)
 276                 /* Only A existed in the original so B is obviously newer */
 277                 return -1;
 278         else if (0 <= (*b)->old_num)
 279                 /* The other way around. */
 280                 return 1;
 281
 282         /* then it does not matter but at least keep the comparison stable */
 283         if ((*a)->p == (*b)->p)
 284                 return 0;
 285         else if ((*a)->p < (*b)->p)
 286                 return -1;
 287         else
 288                 return 1;
 289 }
 290
 291 static void init_pack_info(const char *infofile, int force)
 292 {
 293         struct packed_git *p;
 294         int stale;
 295         int i;
 296         size_t alloc = 0;
 297
 298         for (p = get_all_packs(the_repository); p; p = p->next) {
 299                 /* we ignore things on alternate path since they are
 300                  * not available to the pullers in general.
 301                  */
 302                 if (!p->pack_local || !file_exists(p->pack_name))
 303                         continue;
 304
 305                 i = num_pack++;
 306                 ALLOC_GROW(info, num_pack, alloc);
 307                 CALLOC_ARRAY(info[i], 1);
 308                 info[i]->p = p;
 309                 info[i]->old_num = -1;
 310         }
 311
 312         if (infofile && !force)
 313                 stale = read_pack_info_file(infofile);
 314         else
 315                 stale = 1;
 316
 317         for (i = 0; i < num_pack; i++)
 318                 if (stale)
 319                         info[i]->old_num = -1;
 320
 321         /* renumber them */
 322         QSORT(info, num_pack, compare_info);
 323         for (i = 0; i < num_pack; i++)
 324                 info[i]->new_num = i;
 325 }
 326
 327 static void free_pack_info(void)
 328 {
 329         int i;
 330         for (i = 0; i < num_pack; i++)
 331                 free(info[i]);
 332         free(info);
 333 }
 334
 335 static int write_pack_info_file(struct update_info_ctx *uic)
 336 {
 337         int i;
 338         for (i = 0; i < num_pack; i++) {
 339                 if (uic_printf(uic, "P %s\n", pack_basename(info[i]->p)) < 0)
 340                         return -1;
 341         }
 342         if (uic_printf(uic, "\n") < 0)
 343                 return -1;
 344         return 0;
 345 }
 346
 347 static int update_info_packs(int force)
 348 {
 349         char *infofile = mkpathdup("%s/info/packs", get_object_directory());
 350         int ret;
 351
 352         init_pack_info(infofile, force);
 353         ret = update_info_file(infofile, write_pack_info_file, force);
 354         free_pack_info();
 355         free(infofile);
 356         return ret;
 357 }
 358
 359 /* public */
 360 int update_server_info(int force)
 361 {
 362         /* We would add more dumb-server support files later,
 363          * including index of available pack files and their
 364          * intended audiences.
 365          */
 366         int errs = 0;
 367
 368         errs = errs | update_info_refs(force);
 369         errs = errs | update_info_packs(force);
 370
 371         /* remove leftover rev-cache file if there is any */
 372         unlink_or_warn(git_path("info/rev-cache"));
 373
 374         return errs;
 375 }