archive-tar.c

   1 /*
   2  * Copyright (c) 2005, 2006 Rene Scharfe
   3  */
   4 #include "cache.h"
   5 #include "tar.h"
   6 #include "archive.h"
   7 #include "run-command.h"
   8
   9 #define RECORDSIZE      (512)
  10 #define BLOCKSIZE       (RECORDSIZE * 20)
  11
  12 static char block[BLOCKSIZE];
  13 static unsigned long offset;
  14
  15 static int tar_umask = 002;
  16
  17 static int write_tar_filter_archive(const struct archiver *ar,
  18                                     struct archiver_args *args);
  19
  20 /* writes out the whole block, but only if it is full */
  21 static void write_if_needed(void)
  22 {
  23         if (offset == BLOCKSIZE) {
  24                 write_or_die(1, block, BLOCKSIZE);
  25                 offset = 0;
  26         }
  27 }
  28
  29 /*
  30  * queues up writes, so that all our write(2) calls write exactly one
  31  * full block; pads writes to RECORDSIZE
  32  */
  33 static void write_blocked(const void *data, unsigned long size)
  34 {
  35         const char *buf = data;
  36         unsigned long tail;
  37
  38         if (offset) {
  39                 unsigned long chunk = BLOCKSIZE - offset;
  40                 if (size < chunk)
  41                         chunk = size;
  42                 memcpy(block + offset, buf, chunk);
  43                 size -= chunk;
  44                 offset += chunk;
  45                 buf += chunk;
  46                 write_if_needed();
  47         }
  48         while (size >= BLOCKSIZE) {
  49                 write_or_die(1, buf, BLOCKSIZE);
  50                 size -= BLOCKSIZE;
  51                 buf += BLOCKSIZE;
  52         }
  53         if (size) {
  54                 memcpy(block + offset, buf, size);
  55                 offset += size;
  56         }
  57         tail = offset % RECORDSIZE;
  58         if (tail)  {
  59                 memset(block + offset, 0, RECORDSIZE - tail);
  60                 offset += RECORDSIZE - tail;
  61         }
  62         write_if_needed();
  63 }
  64
  65 /*
  66  * The end of tar archives is marked by 2*512 nul bytes and after that
  67  * follows the rest of the block (if any).
  68  */
  69 static void write_trailer(void)
  70 {
  71         int tail = BLOCKSIZE - offset;
  72         memset(block + offset, 0, tail);
  73         write_or_die(1, block, BLOCKSIZE);
  74         if (tail < 2 * RECORDSIZE) {
  75                 memset(block, 0, offset);
  76                 write_or_die(1, block, BLOCKSIZE);
  77         }
  78 }
  79
  80 /*
  81  * pax extended header records have the format "%u %s=%s\n".  %u contains
  82  * the size of the whole string (including the %u), the first %s is the
  83  * keyword, the second one is the value.  This function constructs such a
  84  * string and appends it to a struct strbuf.
  85  */
  86 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
  87                                      const char *value, unsigned int valuelen)
  88 {
  89         int len, tmp;
  90
  91         /* "%u %s=%s\n" */
  92         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
  93         for (tmp = len; tmp > 9; tmp /= 10)
  94                 len++;
  95
  96         strbuf_grow(sb, len);
  97         strbuf_addf(sb, "%u %s=", len, keyword);
  98         strbuf_add(sb, value, valuelen);
  99         strbuf_addch(sb, '\n');
 100 }
 101
 102 static unsigned int ustar_header_chksum(const struct ustar_header *header)
 103 {
 104         char *p = (char *)header;
 105         unsigned int chksum = 0;
 106         while (p < header->chksum)
 107                 chksum += *p++;
 108         chksum += sizeof(header->chksum) * ' ';
 109         p += sizeof(header->chksum);
 110         while (p < (char *)header + sizeof(struct ustar_header))
 111                 chksum += *p++;
 112         return chksum;
 113 }
 114
 115 static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
 116 {
 117         size_t i = pathlen;
 118         if (i > maxlen)
 119                 i = maxlen;
 120         do {
 121                 i--;
 122         } while (i > 0 && path[i] != '/');
 123         return i;
 124 }
 125
 126 static void prepare_header(struct archiver_args *args,
 127                            struct ustar_header *header,
 128                            unsigned int mode, unsigned long size)
 129 {
 130         sprintf(header->mode, "%07o", mode & 07777);
 131         sprintf(header->size, "%011lo", S_ISREG(mode) ? size : 0);
 132         sprintf(header->mtime, "%011lo", (unsigned long) args->time);
 133
 134         sprintf(header->uid, "%07o", 0);
 135         sprintf(header->gid, "%07o", 0);
 136         strlcpy(header->uname, "root", sizeof(header->uname));
 137         strlcpy(header->gname, "root", sizeof(header->gname));
 138         sprintf(header->devmajor, "%07o", 0);
 139         sprintf(header->devminor, "%07o", 0);
 140
 141         memcpy(header->magic, "ustar", 6);
 142         memcpy(header->version, "00", 2);
 143
 144         sprintf(header->chksum, "%07o", ustar_header_chksum(header));
 145 }
 146
 147 static int write_extended_header(struct archiver_args *args,
 148                                  const unsigned char *sha1,
 149                                  const void *buffer, unsigned long size)
 150 {
 151         struct ustar_header header;
 152         unsigned int mode;
 153         memset(&header, 0, sizeof(header));
 154         *header.typeflag = TYPEFLAG_EXT_HEADER;
 155         mode = 0100666;
 156         sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 157         prepare_header(args, &header, mode, size);
 158         write_blocked(&header, sizeof(header));
 159         write_blocked(buffer, size);
 160         return 0;
 161 }
 162
 163 static int write_tar_entry(struct archiver_args *args,
 164                            const unsigned char *sha1,
 165                            const char *path, size_t pathlen,
 166                            unsigned int mode)
 167 {
 168         struct ustar_header header;
 169         struct strbuf ext_header = STRBUF_INIT;
 170         unsigned int old_mode = mode;
 171         unsigned long size;
 172         void *buffer;
 173         int err = 0;
 174
 175         memset(&header, 0, sizeof(header));
 176
 177         if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 178                 *header.typeflag = TYPEFLAG_DIR;
 179                 mode = (mode | 0777) & ~tar_umask;
 180         } else if (S_ISLNK(mode)) {
 181                 *header.typeflag = TYPEFLAG_LNK;
 182                 mode |= 0777;
 183         } else if (S_ISREG(mode)) {
 184                 *header.typeflag = TYPEFLAG_REG;
 185                 mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 186         } else {
 187                 return error("unsupported file mode: 0%o (SHA1: %s)",
 188                              mode, sha1_to_hex(sha1));
 189         }
 190         if (pathlen > sizeof(header.name)) {
 191                 size_t plen = get_path_prefix(path, pathlen,
 192                                               sizeof(header.prefix));
 193                 size_t rest = pathlen - plen - 1;
 194                 if (plen > 0 && rest <= sizeof(header.name)) {
 195                         memcpy(header.prefix, path, plen);
 196                                 memcpy(header.name, path + plen + 1, rest);
 197                 } else {
 198                         sprintf(header.name, "%s.data",
 199                                 sha1_to_hex(sha1));
 200                         strbuf_append_ext_header(&ext_header, "path",
 201                                                  path, pathlen);
 202                 }
 203         } else
 204                 memcpy(header.name, path, pathlen);
 205
 206         if (S_ISLNK(mode) || S_ISREG(mode)) {
 207                 enum object_type type;
 208                 buffer = sha1_file_to_archive(args, path, sha1, old_mode, &type, &size);
 209                 if (!buffer)
 210                         return error("cannot read %s", sha1_to_hex(sha1));
 211         } else {
 212                 buffer = NULL;
 213                 size = 0;
 214         }
 215
 216         if (S_ISLNK(mode)) {
 217                 if (size > sizeof(header.linkname)) {
 218                         sprintf(header.linkname, "see %s.paxheader",
 219                                 sha1_to_hex(sha1));
 220                         strbuf_append_ext_header(&ext_header, "linkpath",
 221                                                  buffer, size);
 222                 } else
 223                         memcpy(header.linkname, buffer, size);
 224         }
 225
 226         prepare_header(args, &header, mode, size);
 227
 228         if (ext_header.len > 0) {
 229                 err = write_extended_header(args, sha1, ext_header.buf,
 230                                             ext_header.len);
 231                 if (err) {
 232                         free(buffer);
 233                         return err;
 234                 }
 235         }
 236         strbuf_release(&ext_header);
 237         write_blocked(&header, sizeof(header));
 238         if (S_ISREG(mode) && buffer && size > 0)
 239                 write_blocked(buffer, size);
 240         free(buffer);
 241         return err;
 242 }
 243
 244 static int write_global_extended_header(struct archiver_args *args)
 245 {
 246         const unsigned char *sha1 = args->commit_sha1;
 247         struct strbuf ext_header = STRBUF_INIT;
 248         struct ustar_header header;
 249         unsigned int mode;
 250         int err = 0;
 251
 252         strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 253         memset(&header, 0, sizeof(header));
 254         *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 255         mode = 0100666;
 256         strcpy(header.name, "pax_global_header");
 257         prepare_header(args, &header, mode, ext_header.len);
 258         write_blocked(&header, sizeof(header));
 259         write_blocked(ext_header.buf, ext_header.len);
 260         strbuf_release(&ext_header);
 261         return err;
 262 }
 263
 264 static struct archiver **tar_filters;
 265 static int nr_tar_filters;
 266 static int alloc_tar_filters;
 267
 268 static struct archiver *find_tar_filter(const char *name, int len)
 269 {
 270         int i;
 271         for (i = 0; i < nr_tar_filters; i++) {
 272                 struct archiver *ar = tar_filters[i];
 273                 if (!strncmp(ar->name, name, len) && !ar->name[len])
 274                         return ar;
 275         }
 276         return NULL;
 277 }
 278
 279 static int tar_filter_config(const char *var, const char *value, void *data)
 280 {
 281         struct archiver *ar;
 282         const char *dot;
 283         const char *name;
 284         const char *type;
 285         int namelen;
 286
 287         if (prefixcmp(var, "tar."))
 288                 return 0;
 289         dot = strrchr(var, '.');
 290         if (dot == var + 9)
 291                 return 0;
 292
 293         name = var + 4;
 294         namelen = dot - name;
 295         type = dot + 1;
 296
 297         ar = find_tar_filter(name, namelen);
 298         if (!ar) {
 299                 ar = xcalloc(1, sizeof(*ar));
 300                 ar->name = xmemdupz(name, namelen);
 301                 ar->write_archive = write_tar_filter_archive;
 302                 ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS;
 303                 ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
 304                 tar_filters[nr_tar_filters++] = ar;
 305         }
 306
 307         if (!strcmp(type, "command")) {
 308                 if (!value)
 309                         return config_error_nonbool(var);
 310                 free(ar->data);
 311                 ar->data = xstrdup(value);
 312                 return 0;
 313         }
 314         if (!strcmp(type, "remote")) {
 315                 if (git_config_bool(var, value))
 316                         ar->flags |= ARCHIVER_REMOTE;
 317                 else
 318                         ar->flags &= ~ARCHIVER_REMOTE;
 319                 return 0;
 320         }
 321
 322         return 0;
 323 }
 324
 325 static int git_tar_config(const char *var, const char *value, void *cb)
 326 {
 327         if (!strcmp(var, "tar.umask")) {
 328                 if (value && !strcmp(value, "user")) {
 329                         tar_umask = umask(0);
 330                         umask(tar_umask);
 331                 } else {
 332                         tar_umask = git_config_int(var, value);
 333                 }
 334                 return 0;
 335         }
 336
 337         return tar_filter_config(var, value, cb);
 338 }
 339
 340 static int write_tar_archive(const struct archiver *ar,
 341                              struct archiver_args *args)
 342 {
 343         int err = 0;
 344
 345         if (args->commit_sha1)
 346                 err = write_global_extended_header(args);
 347         if (!err)
 348                 err = write_archive_entries(args, write_tar_entry);
 349         if (!err)
 350                 write_trailer();
 351         return err;
 352 }
 353
 354 static int write_tar_filter_archive(const struct archiver *ar,
 355                                     struct archiver_args *args)
 356 {
 357         struct strbuf cmd = STRBUF_INIT;
 358         struct child_process filter;
 359         const char *argv[2];
 360         int r;
 361
 362         if (!ar->data)
 363                 die("BUG: tar-filter archiver called with no filter defined");
 364
 365         strbuf_addstr(&cmd, ar->data);
 366         if (args->compression_level >= 0)
 367                 strbuf_addf(&cmd, " -%d", args->compression_level);
 368
 369         memset(&filter, 0, sizeof(filter));
 370         argv[0] = cmd.buf;
 371         argv[1] = NULL;
 372         filter.argv = argv;
 373         filter.use_shell = 1;
 374         filter.in = -1;
 375
 376         if (start_command(&filter) < 0)
 377                 die_errno("unable to start '%s' filter", argv[0]);
 378         close(1);
 379         if (dup2(filter.in, 1) < 0)
 380                 die_errno("unable to redirect descriptor");
 381         close(filter.in);
 382
 383         r = write_tar_archive(ar, args);
 384
 385         close(1);
 386         if (finish_command(&filter) != 0)
 387                 die("'%s' filter reported error", argv[0]);
 388
 389         strbuf_release(&cmd);
 390         return r;
 391 }
 392
 393 static struct archiver tar_archiver = {
 394         "tar",
 395         write_tar_archive,
 396         ARCHIVER_REMOTE
 397 };
 398
 399 void init_tar_archiver(void)
 400 {
 401         int i;
 402         register_archiver(&tar_archiver);
 403
 404         tar_filter_config("tar.tgz.command", "gzip -cn", NULL);
 405         tar_filter_config("tar.tgz.remote", "true", NULL);
 406         tar_filter_config("tar.tar.gz.command", "gzip -cn", NULL);
 407         tar_filter_config("tar.tar.gz.remote", "true", NULL);
 408         git_config(git_tar_config, NULL);
 409         for (i = 0; i < nr_tar_filters; i++) {
 410                 /* omit any filters that never had a command configured */
 411                 if (tar_filters[i]->data)
 412                         register_archiver(tar_filters[i]);
 413         }
 414 }