server-info.c

   1 #include "cache.h"
   2 #include "refs.h"
   3 #include "object.h"
   4 #include "commit.h"
   5 #include "tag.h"
   6
   7 /*
   8  * Create the file "path" by writing to a temporary file and renaming
   9  * it into place. The contents of the file come from "generate", which
  10  * should return non-zero if it encounters an error.
  11  */
  12 static int update_info_file(char *path, int (*generate)(FILE *))
  13 {
  14         char *tmp = mkpathdup("%s_XXXXXX", path);
  15         int ret = -1;
  16         int fd = -1;
  17         FILE *fp = NULL;
  18
  19         safe_create_leading_directories(path);
  20         fd = git_mkstemp_mode(tmp, 0666);
  21         if (fd < 0)
  22                 goto out;
  23         fp = fdopen(fd, "w");
  24         if (!fp)
  25                 goto out;
  26         ret = generate(fp);
  27         if (ret)
  28                 goto out;
  29         if (fclose(fp))
  30                 goto out;
  31         if (adjust_shared_perm(tmp) < 0)
  32                 goto out;
  33         if (rename(tmp, path) < 0)
  34                 goto out;
  35         ret = 0;
  36
  37 out:
  38         if (ret) {
  39                 error("unable to update %s: %s", path, strerror(errno));
  40                 if (fp)
  41                         fclose(fp);
  42                 else if (fd >= 0)
  43                         close(fd);
  44                 unlink(tmp);
  45         }
  46         free(tmp);
  47         return ret;
  48 }
  49
  50 static int add_info_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
  51 {
  52         FILE *fp = cb_data;
  53         struct object *o = parse_object(sha1);
  54         if (!o)
  55                 return -1;
  56
  57         if (fprintf(fp, "%s     %s\n", sha1_to_hex(sha1), path) < 0)
  58                 return -1;
  59
  60         if (o->type == OBJ_TAG) {
  61                 o = deref_tag(o, path, 0);
  62                 if (o)
  63                         if (fprintf(fp, "%s     %s^{}\n",
  64                                 sha1_to_hex(o->sha1), path) < 0)
  65                                 return -1;
  66         }
  67         return 0;
  68 }
  69
  70 static int generate_info_refs(FILE *fp)
  71 {
  72         return for_each_ref(add_info_ref, fp);
  73 }
  74
  75 static int update_info_refs(int force)
  76 {
  77         char *path = git_pathdup("info/refs");
  78         int ret = update_info_file(path, generate_info_refs);
  79         free(path);
  80         return ret;
  81 }
  82
  83 /* packs */
  84 static struct pack_info {
  85         struct packed_git *p;
  86         int old_num;
  87         int new_num;
  88         int nr_alloc;
  89         int nr_heads;
  90         unsigned char (*head)[20];
  91 } **info;
  92 static int num_pack;
  93 static const char *objdir;
  94 static int objdirlen;
  95
  96 static struct pack_info *find_pack_by_name(const char *name)
  97 {
  98         int i;
  99         for (i = 0; i < num_pack; i++) {
 100                 struct packed_git *p = info[i]->p;
 101                 /* skip "/pack/" after ".git/objects" */
 102                 if (!strcmp(p->pack_name + objdirlen + 6, name))
 103                         return info[i];
 104         }
 105         return NULL;
 106 }
 107
 108 /* Returns non-zero when we detect that the info in the
 109  * old file is useless.
 110  */
 111 static int parse_pack_def(const char *line, int old_cnt)
 112 {
 113         struct pack_info *i = find_pack_by_name(line + 2);
 114         if (i) {
 115                 i->old_num = old_cnt;
 116                 return 0;
 117         }
 118         else {
 119                 /* The file describes a pack that is no longer here */
 120                 return 1;
 121         }
 122 }
 123
 124 /* Returns non-zero when we detect that the info in the
 125  * old file is useless.
 126  */
 127 static int read_pack_info_file(const char *infofile)
 128 {
 129         FILE *fp;
 130         char line[1000];
 131         int old_cnt = 0;
 132
 133         fp = fopen(infofile, "r");
 134         if (!fp)
 135                 return 1; /* nonexistent is not an error. */
 136
 137         while (fgets(line, sizeof(line), fp)) {
 138                 int len = strlen(line);
 139                 if (len && line[len-1] == '\n')
 140                         line[--len] = 0;
 141
 142                 if (!len)
 143                         continue;
 144
 145                 switch (line[0]) {
 146                 case 'P': /* P name */
 147                         if (parse_pack_def(line, old_cnt++))
 148                                 goto out_stale;
 149                         break;
 150                 case 'D': /* we used to emit D but that was misguided. */
 151                 case 'T': /* we used to emit T but nobody uses it. */
 152                         goto out_stale;
 153                 default:
 154                         error("unrecognized: %s", line);
 155                         break;
 156                 }
 157         }
 158         fclose(fp);
 159         return 0;
 160  out_stale:
 161         fclose(fp);
 162         return 1;
 163 }
 164
 165 static int compare_info(const void *a_, const void *b_)
 166 {
 167         struct pack_info *const *a = a_;
 168         struct pack_info *const *b = b_;
 169
 170         if (0 <= (*a)->old_num && 0 <= (*b)->old_num)
 171                 /* Keep the order in the original */
 172                 return (*a)->old_num - (*b)->old_num;
 173         else if (0 <= (*a)->old_num)
 174                 /* Only A existed in the original so B is obviously newer */
 175                 return -1;
 176         else if (0 <= (*b)->old_num)
 177                 /* The other way around. */
 178                 return 1;
 179
 180         /* then it does not matter but at least keep the comparison stable */
 181         if ((*a)->p == (*b)->p)
 182                 return 0;
 183         else if ((*a)->p < (*b)->p)
 184                 return -1;
 185         else
 186                 return 1;
 187 }
 188
 189 static void init_pack_info(const char *infofile, int force)
 190 {
 191         struct packed_git *p;
 192         int stale;
 193         int i = 0;
 194
 195         objdir = get_object_directory();
 196         objdirlen = strlen(objdir);
 197
 198         prepare_packed_git();
 199         for (p = packed_git; p; p = p->next) {
 200                 /* we ignore things on alternate path since they are
 201                  * not available to the pullers in general.
 202                  */
 203                 if (!p->pack_local)
 204                         continue;
 205                 i++;
 206         }
 207         num_pack = i;
 208         info = xcalloc(num_pack, sizeof(struct pack_info *));
 209         for (i = 0, p = packed_git; p; p = p->next) {
 210                 if (!p->pack_local)
 211                         continue;
 212                 info[i] = xcalloc(1, sizeof(struct pack_info));
 213                 info[i]->p = p;
 214                 info[i]->old_num = -1;
 215                 i++;
 216         }
 217
 218         if (infofile && !force)
 219                 stale = read_pack_info_file(infofile);
 220         else
 221                 stale = 1;
 222
 223         for (i = 0; i < num_pack; i++) {
 224                 if (stale) {
 225                         info[i]->old_num = -1;
 226                         info[i]->nr_heads = 0;
 227                 }
 228         }
 229
 230         /* renumber them */
 231         qsort(info, num_pack, sizeof(info[0]), compare_info);
 232         for (i = 0; i < num_pack; i++)
 233                 info[i]->new_num = i;
 234 }
 235
 236 static void free_pack_info(void)
 237 {
 238         int i;
 239         for (i = 0; i < num_pack; i++)
 240                 free(info[i]);
 241         free(info);
 242 }
 243
 244 static int write_pack_info_file(FILE *fp)
 245 {
 246         int i;
 247         for (i = 0; i < num_pack; i++) {
 248                 if (fprintf(fp, "P %s\n", info[i]->p->pack_name + objdirlen + 6) < 0)
 249                         return -1;
 250         }
 251         if (fputc('\n', fp) == EOF)
 252                 return -1;
 253         return 0;
 254 }
 255
 256 static int update_info_packs(int force)
 257 {
 258         char *infofile = mkpathdup("%s/info/packs", get_object_directory());
 259         int ret;
 260
 261         init_pack_info(infofile, force);
 262         ret = update_info_file(infofile, write_pack_info_file);
 263         free_pack_info();
 264         free(infofile);
 265         return ret;
 266 }
 267
 268 /* public */
 269 int update_server_info(int force)
 270 {
 271         /* We would add more dumb-server support files later,
 272          * including index of available pack files and their
 273          * intended audiences.
 274          */
 275         int errs = 0;
 276
 277         errs = errs | update_info_refs(force);
 278         errs = errs | update_info_packs(force);
 279
 280         /* remove leftover rev-cache file if there is any */
 281         unlink_or_warn(git_path("info/rev-cache"));
 282
 283         return errs;
 284 }