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, void *cb_data)
 151 {
 152         struct update_info_ctx *uic = cb_data;
 153         struct object *o = parse_object(the_repository, oid);
 154         if (!o)
 155                 return -1;
 156
 157         if (uic_printf(uic, "%s %s\n", oid_to_hex(oid), path) < 0)
 158                 return -1;
 159
 160         if (o->type == OBJ_TAG) {
 161                 o = deref_tag(the_repository, o, path, 0);
 162                 if (o)
 163                         if (uic_printf(uic, "%s %s^{}\n",
 164                                 oid_to_hex(&o->oid), path) < 0)
 165                                 return -1;
 166         }
 167         return 0;
 168 }
 169
 170 static int generate_info_refs(struct update_info_ctx *uic)
 171 {
 172         return for_each_ref(add_info_ref, uic);
 173 }
 174
 175 static int update_info_refs(int force)
 176 {
 177         char *path = git_pathdup("info/refs");
 178         int ret = update_info_file(path, generate_info_refs, force);
 179         free(path);
 180         return ret;
 181 }
 182
 183 /* packs */
 184 static struct pack_info {
 185         struct packed_git *p;
 186         int old_num;
 187         int new_num;
 188 } **info;
 189 static int num_pack;
 190
 191 static struct pack_info *find_pack_by_name(const char *name)
 192 {
 193         int i;
 194         for (i = 0; i < num_pack; i++) {
 195                 struct packed_git *p = info[i]->p;
 196                 if (!strcmp(pack_basename(p), name))
 197                         return info[i];
 198         }
 199         return NULL;
 200 }
 201
 202 /* Returns non-zero when we detect that the info in the
 203  * old file is useless.
 204  */
 205 static int parse_pack_def(const char *packname, int old_cnt)
 206 {
 207         struct pack_info *i = find_pack_by_name(packname);
 208         if (i) {
 209                 i->old_num = old_cnt;
 210                 return 0;
 211         }
 212         else {
 213                 /* The file describes a pack that is no longer here */
 214                 return 1;
 215         }
 216 }
 217
 218 /* Returns non-zero when we detect that the info in the
 219  * old file is useless.
 220  */
 221 static int read_pack_info_file(const char *infofile)
 222 {
 223         FILE *fp;
 224         struct strbuf line = STRBUF_INIT;
 225         int old_cnt = 0;
 226         int stale = 1;
 227
 228         fp = fopen_or_warn(infofile, "r");
 229         if (!fp)
 230                 return 1; /* nonexistent is not an error. */
 231
 232         while (strbuf_getline(&line, fp) != EOF) {
 233                 const char *arg;
 234
 235                 if (!line.len)
 236                         continue;
 237
 238                 if (skip_prefix(line.buf, "P ", &arg)) {
 239                         /* P name */
 240                         if (parse_pack_def(arg, old_cnt++))
 241                                 goto out_stale;
 242                 } else if (line.buf[0] == 'D') {
 243                         /* we used to emit D but that was misguided. */
 244                         goto out_stale;
 245                 } else if (line.buf[0] == 'T') {
 246                         /* we used to emit T but nobody uses it. */
 247                         goto out_stale;
 248                 } else {
 249                         error("unrecognized: %s", line.buf);
 250                 }
 251         }
 252         stale = 0;
 253
 254  out_stale:
 255         strbuf_release(&line);
 256         fclose(fp);
 257         return stale;
 258 }
 259
 260 static int compare_info(const void *a_, const void *b_)
 261 {
 262         struct pack_info *const *a = a_;
 263         struct pack_info *const *b = b_;
 264
 265         if (0 <= (*a)->old_num && 0 <= (*b)->old_num)
 266                 /* Keep the order in the original */
 267                 return (*a)->old_num - (*b)->old_num;
 268         else if (0 <= (*a)->old_num)
 269                 /* Only A existed in the original so B is obviously newer */
 270                 return -1;
 271         else if (0 <= (*b)->old_num)
 272                 /* The other way around. */
 273                 return 1;
 274
 275         /* then it does not matter but at least keep the comparison stable */
 276         if ((*a)->p == (*b)->p)
 277                 return 0;
 278         else if ((*a)->p < (*b)->p)
 279                 return -1;
 280         else
 281                 return 1;
 282 }
 283
 284 static void init_pack_info(const char *infofile, int force)
 285 {
 286         struct packed_git *p;
 287         int stale;
 288         int i;
 289         size_t alloc = 0;
 290
 291         for (p = get_all_packs(the_repository); p; p = p->next) {
 292                 /* we ignore things on alternate path since they are
 293                  * not available to the pullers in general.
 294                  */
 295                 if (!p->pack_local || !file_exists(p->pack_name))
 296                         continue;
 297
 298                 i = num_pack++;
 299                 ALLOC_GROW(info, num_pack, alloc);
 300                 CALLOC_ARRAY(info[i], 1);
 301                 info[i]->p = p;
 302                 info[i]->old_num = -1;
 303         }
 304
 305         if (infofile && !force)
 306                 stale = read_pack_info_file(infofile);
 307         else
 308                 stale = 1;
 309
 310         for (i = 0; i < num_pack; i++)
 311                 if (stale)
 312                         info[i]->old_num = -1;
 313
 314         /* renumber them */
 315         QSORT(info, num_pack, compare_info);
 316         for (i = 0; i < num_pack; i++)
 317                 info[i]->new_num = i;
 318 }
 319
 320 static void free_pack_info(void)
 321 {
 322         int i;
 323         for (i = 0; i < num_pack; i++)
 324                 free(info[i]);
 325         free(info);
 326 }
 327
 328 static int write_pack_info_file(struct update_info_ctx *uic)
 329 {
 330         int i;
 331         for (i = 0; i < num_pack; i++) {
 332                 if (uic_printf(uic, "P %s\n", pack_basename(info[i]->p)) < 0)
 333                         return -1;
 334         }
 335         if (uic_printf(uic, "\n") < 0)
 336                 return -1;
 337         return 0;
 338 }
 339
 340 static int update_info_packs(int force)
 341 {
 342         char *infofile = mkpathdup("%s/info/packs", get_object_directory());
 343         int ret;
 344
 345         init_pack_info(infofile, force);
 346         ret = update_info_file(infofile, write_pack_info_file, force);
 347         free_pack_info();
 348         free(infofile);
 349         return ret;
 350 }
 351
 352 /* public */
 353 int update_server_info(int force)
 354 {
 355         /* We would add more dumb-server support files later,
 356          * including index of available pack files and their
 357          * intended audiences.
 358          */
 359         int errs = 0;
 360
 361         errs = errs | update_info_refs(force);
 362         errs = errs | update_info_packs(force);
 363
 364         /* remove leftover rev-cache file if there is any */
 365         unlink_or_warn(git_path("info/rev-cache"));
 366
 367         return errs;
 368 }