archive-tar.c

   1 /*
   2  * Copyright (c) 2005, 2006 Rene Scharfe
   3  */
   4 #include "cache.h"
   5 #include "config.h"
   6 #include "tar.h"
   7 #include "archive.h"
   8 #include "object-store.h"
   9 #include "streaming.h"
  10 #include "run-command.h"
  11
  12 #define RECORDSIZE      (512)
  13 #define BLOCKSIZE       (RECORDSIZE * 20)
  14
  15 static char block[BLOCKSIZE];
  16 static unsigned long offset;
  17
  18 static int tar_umask = 002;
  19
  20 static int write_tar_filter_archive(const struct archiver *ar,
  21                                     struct archiver_args *args);
  22
  23 /*
  24  * This is the max value that a ustar size header can specify, as it is fixed
  25  * at 11 octal digits. POSIX specifies that we switch to extended headers at
  26  * this size.
  27  *
  28  * Likewise for the mtime (which happens to use a buffer of the same size).
  29  */
  30 #if ULONG_MAX == 0xFFFFFFFF
  31 #define USTAR_MAX_SIZE ULONG_MAX
  32 #else
  33 #define USTAR_MAX_SIZE 077777777777UL
  34 #endif
  35 #if TIME_MAX == 0xFFFFFFFF
  36 #define USTAR_MAX_MTIME TIME_MAX
  37 #else
  38 #define USTAR_MAX_MTIME 077777777777ULL
  39 #endif
  40
  41 /* writes out the whole block, but only if it is full */
  42 static void write_if_needed(void)
  43 {
  44         if (offset == BLOCKSIZE) {
  45                 write_or_die(1, block, BLOCKSIZE);
  46                 offset = 0;
  47         }
  48 }
  49
  50 /*
  51  * queues up writes, so that all our write(2) calls write exactly one
  52  * full block; pads writes to RECORDSIZE
  53  */
  54 static void do_write_blocked(const void *data, unsigned long size)
  55 {
  56         const char *buf = data;
  57
  58         if (offset) {
  59                 unsigned long chunk = BLOCKSIZE - offset;
  60                 if (size < chunk)
  61                         chunk = size;
  62                 memcpy(block + offset, buf, chunk);
  63                 size -= chunk;
  64                 offset += chunk;
  65                 buf += chunk;
  66                 write_if_needed();
  67         }
  68         while (size >= BLOCKSIZE) {
  69                 write_or_die(1, buf, BLOCKSIZE);
  70                 size -= BLOCKSIZE;
  71                 buf += BLOCKSIZE;
  72         }
  73         if (size) {
  74                 memcpy(block + offset, buf, size);
  75                 offset += size;
  76         }
  77 }
  78
  79 static void finish_record(void)
  80 {
  81         unsigned long tail;
  82         tail = offset % RECORDSIZE;
  83         if (tail)  {
  84                 memset(block + offset, 0, RECORDSIZE - tail);
  85                 offset += RECORDSIZE - tail;
  86         }
  87         write_if_needed();
  88 }
  89
  90 static void write_blocked(const void *data, unsigned long size)
  91 {
  92         do_write_blocked(data, size);
  93         finish_record();
  94 }
  95
  96 /*
  97  * The end of tar archives is marked by 2*512 nul bytes and after that
  98  * follows the rest of the block (if any).
  99  */
 100 static void write_trailer(void)
 101 {
 102         int tail = BLOCKSIZE - offset;
 103         memset(block + offset, 0, tail);
 104         write_or_die(1, block, BLOCKSIZE);
 105         if (tail < 2 * RECORDSIZE) {
 106                 memset(block, 0, offset);
 107                 write_or_die(1, block, BLOCKSIZE);
 108         }
 109 }
 110
 111 /*
 112  * queues up writes, so that all our write(2) calls write exactly one
 113  * full block; pads writes to RECORDSIZE
 114  */
 115 static int stream_blocked(const struct object_id *oid)
 116 {
 117         struct git_istream *st;
 118         enum object_type type;
 119         unsigned long sz;
 120         char buf[BLOCKSIZE];
 121         ssize_t readlen;
 122
 123         st = open_istream(oid, &type, &sz, NULL);
 124         if (!st)
 125                 return error(_("cannot stream blob %s"), oid_to_hex(oid));
 126         for (;;) {
 127                 readlen = read_istream(st, buf, sizeof(buf));
 128                 if (readlen <= 0)
 129                         break;
 130                 do_write_blocked(buf, readlen);
 131         }
 132         close_istream(st);
 133         if (!readlen)
 134                 finish_record();
 135         return readlen;
 136 }
 137
 138 /*
 139  * pax extended header records have the format "%u %s=%s\n".  %u contains
 140  * the size of the whole string (including the %u), the first %s is the
 141  * keyword, the second one is the value.  This function constructs such a
 142  * string and appends it to a struct strbuf.
 143  */
 144 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 145                                      const char *value, size_t valuelen)
 146 {
 147         size_t orig_len = sb->len;
 148         size_t len, tmp;
 149
 150         /* "%u %s=%s\n" */
 151         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 152         for (tmp = 1; len / 10 >= tmp; tmp *= 10)
 153                 len++;
 154
 155         strbuf_grow(sb, len);
 156         strbuf_addf(sb, "%"PRIuMAX" %s=", (uintmax_t)len, keyword);
 157         strbuf_add(sb, value, valuelen);
 158         strbuf_addch(sb, '\n');
 159
 160         if (len != sb->len - orig_len)
 161                 BUG("pax extended header length miscalculated as %"PRIuMAX
 162                     ", should be %"PRIuMAX,
 163                     (uintmax_t)len, (uintmax_t)(sb->len - orig_len));
 164 }
 165
 166 /*
 167  * Like strbuf_append_ext_header, but for numeric values.
 168  */
 169 static void strbuf_append_ext_header_uint(struct strbuf *sb,
 170                                           const char *keyword,
 171                                           uintmax_t value)
 172 {
 173         char buf[40]; /* big enough for 2^128 in decimal, plus NUL */
 174         int len;
 175
 176         len = xsnprintf(buf, sizeof(buf), "%"PRIuMAX, value);
 177         strbuf_append_ext_header(sb, keyword, buf, len);
 178 }
 179
 180 static unsigned int ustar_header_chksum(const struct ustar_header *header)
 181 {
 182         const unsigned char *p = (const unsigned char *)header;
 183         unsigned int chksum = 0;
 184         while (p < (const unsigned char *)header->chksum)
 185                 chksum += *p++;
 186         chksum += sizeof(header->chksum) * ' ';
 187         p += sizeof(header->chksum);
 188         while (p < (const unsigned char *)header + sizeof(struct ustar_header))
 189                 chksum += *p++;
 190         return chksum;
 191 }
 192
 193 static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
 194 {
 195         size_t i = pathlen;
 196         if (i > 1 && path[i - 1] == '/')
 197                 i--;
 198         if (i > maxlen)
 199                 i = maxlen;
 200         do {
 201                 i--;
 202         } while (i > 0 && path[i] != '/');
 203         return i;
 204 }
 205
 206 static void prepare_header(struct archiver_args *args,
 207                            struct ustar_header *header,
 208                            unsigned int mode, unsigned long size)
 209 {
 210         xsnprintf(header->mode, sizeof(header->mode), "%07o", mode & 07777);
 211         xsnprintf(header->size, sizeof(header->size), "%011"PRIoMAX , S_ISREG(mode) ? (uintmax_t)size : (uintmax_t)0);
 212         xsnprintf(header->mtime, sizeof(header->mtime), "%011lo", (unsigned long) args->time);
 213
 214         xsnprintf(header->uid, sizeof(header->uid), "%07o", 0);
 215         xsnprintf(header->gid, sizeof(header->gid), "%07o", 0);
 216         strlcpy(header->uname, "root", sizeof(header->uname));
 217         strlcpy(header->gname, "root", sizeof(header->gname));
 218         xsnprintf(header->devmajor, sizeof(header->devmajor), "%07o", 0);
 219         xsnprintf(header->devminor, sizeof(header->devminor), "%07o", 0);
 220
 221         memcpy(header->magic, "ustar", 6);
 222         memcpy(header->version, "00", 2);
 223
 224         xsnprintf(header->chksum, sizeof(header->chksum), "%07o", ustar_header_chksum(header));
 225 }
 226
 227 static void write_extended_header(struct archiver_args *args,
 228                                   const struct object_id *oid,
 229                                   const void *buffer, unsigned long size)
 230 {
 231         struct ustar_header header;
 232         unsigned int mode;
 233         memset(&header, 0, sizeof(header));
 234         *header.typeflag = TYPEFLAG_EXT_HEADER;
 235         mode = 0100666;
 236         xsnprintf(header.name, sizeof(header.name), "%s.paxheader", oid_to_hex(oid));
 237         prepare_header(args, &header, mode, size);
 238         write_blocked(&header, sizeof(header));
 239         write_blocked(buffer, size);
 240 }
 241
 242 static int write_tar_entry(struct archiver_args *args,
 243                            const struct object_id *oid,
 244                            const char *path, size_t pathlen,
 245                            unsigned int mode)
 246 {
 247         struct ustar_header header;
 248         struct strbuf ext_header = STRBUF_INIT;
 249         unsigned int old_mode = mode;
 250         unsigned long size, size_in_header;
 251         void *buffer;
 252         int err = 0;
 253
 254         memset(&header, 0, sizeof(header));
 255
 256         if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 257                 *header.typeflag = TYPEFLAG_DIR;
 258                 mode = (mode | 0777) & ~tar_umask;
 259         } else if (S_ISLNK(mode)) {
 260                 *header.typeflag = TYPEFLAG_LNK;
 261                 mode |= 0777;
 262         } else if (S_ISREG(mode)) {
 263                 *header.typeflag = TYPEFLAG_REG;
 264                 mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 265         } else {
 266                 return error(_("unsupported file mode: 0%o (SHA1: %s)"),
 267                              mode, oid_to_hex(oid));
 268         }
 269         if (pathlen > sizeof(header.name)) {
 270                 size_t plen = get_path_prefix(path, pathlen,
 271                                               sizeof(header.prefix));
 272                 size_t rest = pathlen - plen - 1;
 273                 if (plen > 0 && rest <= sizeof(header.name)) {
 274                         memcpy(header.prefix, path, plen);
 275                         memcpy(header.name, path + plen + 1, rest);
 276                 } else {
 277                         xsnprintf(header.name, sizeof(header.name), "%s.data",
 278                                   oid_to_hex(oid));
 279                         strbuf_append_ext_header(&ext_header, "path",
 280                                                  path, pathlen);
 281                 }
 282         } else
 283                 memcpy(header.name, path, pathlen);
 284
 285         if (S_ISREG(mode) && !args->convert &&
 286             oid_object_info(args->repo, oid, &size) == OBJ_BLOB &&
 287             size > big_file_threshold)
 288                 buffer = NULL;
 289         else if (S_ISLNK(mode) || S_ISREG(mode)) {
 290                 enum object_type type;
 291                 buffer = object_file_to_archive(args, path, oid, old_mode, &type, &size);
 292                 if (!buffer)
 293                         return error(_("cannot read %s"), oid_to_hex(oid));
 294         } else {
 295                 buffer = NULL;
 296                 size = 0;
 297         }
 298
 299         if (S_ISLNK(mode)) {
 300                 if (size > sizeof(header.linkname)) {
 301                         xsnprintf(header.linkname, sizeof(header.linkname),
 302                                   "see %s.paxheader", oid_to_hex(oid));
 303                         strbuf_append_ext_header(&ext_header, "linkpath",
 304                                                  buffer, size);
 305                 } else
 306                         memcpy(header.linkname, buffer, size);
 307         }
 308
 309         size_in_header = size;
 310         if (S_ISREG(mode) && size > USTAR_MAX_SIZE) {
 311                 size_in_header = 0;
 312                 strbuf_append_ext_header_uint(&ext_header, "size", size);
 313         }
 314
 315         prepare_header(args, &header, mode, size_in_header);
 316
 317         if (ext_header.len > 0) {
 318                 write_extended_header(args, oid, ext_header.buf,
 319                                       ext_header.len);
 320         }
 321         strbuf_release(&ext_header);
 322         write_blocked(&header, sizeof(header));
 323         if (S_ISREG(mode) && size > 0) {
 324                 if (buffer)
 325                         write_blocked(buffer, size);
 326                 else
 327                         err = stream_blocked(oid);
 328         }
 329         free(buffer);
 330         return err;
 331 }
 332
 333 static void write_global_extended_header(struct archiver_args *args)
 334 {
 335         const struct object_id *oid = args->commit_oid;
 336         struct strbuf ext_header = STRBUF_INIT;
 337         struct ustar_header header;
 338         unsigned int mode;
 339
 340         if (oid)
 341                 strbuf_append_ext_header(&ext_header, "comment",
 342                                          oid_to_hex(oid),
 343                                          the_hash_algo->hexsz);
 344         if (args->time > USTAR_MAX_MTIME) {
 345                 strbuf_append_ext_header_uint(&ext_header, "mtime",
 346                                               args->time);
 347                 args->time = USTAR_MAX_MTIME;
 348         }
 349
 350         if (!ext_header.len)
 351                 return;
 352
 353         memset(&header, 0, sizeof(header));
 354         *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 355         mode = 0100666;
 356         xsnprintf(header.name, sizeof(header.name), "pax_global_header");
 357         prepare_header(args, &header, mode, ext_header.len);
 358         write_blocked(&header, sizeof(header));
 359         write_blocked(ext_header.buf, ext_header.len);
 360         strbuf_release(&ext_header);
 361 }
 362
 363 static struct archiver **tar_filters;
 364 static int nr_tar_filters;
 365 static int alloc_tar_filters;
 366
 367 static struct archiver *find_tar_filter(const char *name, int len)
 368 {
 369         int i;
 370         for (i = 0; i < nr_tar_filters; i++) {
 371                 struct archiver *ar = tar_filters[i];
 372                 if (!strncmp(ar->name, name, len) && !ar->name[len])
 373                         return ar;
 374         }
 375         return NULL;
 376 }
 377
 378 static int tar_filter_config(const char *var, const char *value, void *data)
 379 {
 380         struct archiver *ar;
 381         const char *name;
 382         const char *type;
 383         int namelen;
 384
 385         if (parse_config_key(var, "tar", &name, &namelen, &type) < 0 || !name)
 386                 return 0;
 387
 388         ar = find_tar_filter(name, namelen);
 389         if (!ar) {
 390                 ar = xcalloc(1, sizeof(*ar));
 391                 ar->name = xmemdupz(name, namelen);
 392                 ar->write_archive = write_tar_filter_archive;
 393                 ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS;
 394                 ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
 395                 tar_filters[nr_tar_filters++] = ar;
 396         }
 397
 398         if (!strcmp(type, "command")) {
 399                 if (!value)
 400                         return config_error_nonbool(var);
 401                 free(ar->data);
 402                 ar->data = xstrdup(value);
 403                 return 0;
 404         }
 405         if (!strcmp(type, "remote")) {
 406                 if (git_config_bool(var, value))
 407                         ar->flags |= ARCHIVER_REMOTE;
 408                 else
 409                         ar->flags &= ~ARCHIVER_REMOTE;
 410                 return 0;
 411         }
 412
 413         return 0;
 414 }
 415
 416 static int git_tar_config(const char *var, const char *value, void *cb)
 417 {
 418         if (!strcmp(var, "tar.umask")) {
 419                 if (value && !strcmp(value, "user")) {
 420                         tar_umask = umask(0);
 421                         umask(tar_umask);
 422                 } else {
 423                         tar_umask = git_config_int(var, value);
 424                 }
 425                 return 0;
 426         }
 427
 428         return tar_filter_config(var, value, cb);
 429 }
 430
 431 static int write_tar_archive(const struct archiver *ar,
 432                              struct archiver_args *args)
 433 {
 434         int err = 0;
 435
 436         write_global_extended_header(args);
 437         err = write_archive_entries(args, write_tar_entry);
 438         if (!err)
 439                 write_trailer();
 440         return err;
 441 }
 442
 443 static int write_tar_filter_archive(const struct archiver *ar,
 444                                     struct archiver_args *args)
 445 {
 446         struct strbuf cmd = STRBUF_INIT;
 447         struct child_process filter = CHILD_PROCESS_INIT;
 448         const char *argv[2];
 449         int r;
 450
 451         if (!ar->data)
 452                 BUG("tar-filter archiver called with no filter defined");
 453
 454         strbuf_addstr(&cmd, ar->data);
 455         if (args->compression_level >= 0)
 456                 strbuf_addf(&cmd, " -%d", args->compression_level);
 457
 458         argv[0] = cmd.buf;
 459         argv[1] = NULL;
 460         filter.argv = argv;
 461         filter.use_shell = 1;
 462         filter.in = -1;
 463
 464         if (start_command(&filter) < 0)
 465                 die_errno(_("unable to start '%s' filter"), argv[0]);
 466         close(1);
 467         if (dup2(filter.in, 1) < 0)
 468                 die_errno(_("unable to redirect descriptor"));
 469         close(filter.in);
 470
 471         r = write_tar_archive(ar, args);
 472
 473         close(1);
 474         if (finish_command(&filter) != 0)
 475                 die(_("'%s' filter reported error"), argv[0]);
 476
 477         strbuf_release(&cmd);
 478         return r;
 479 }
 480
 481 static struct archiver tar_archiver = {
 482         "tar",
 483         write_tar_archive,
 484         ARCHIVER_REMOTE
 485 };
 486
 487 void init_tar_archiver(void)
 488 {
 489         int i;
 490         register_archiver(&tar_archiver);
 491
 492         tar_filter_config("tar.tgz.command", "gzip -cn", NULL);
 493         tar_filter_config("tar.tgz.remote", "true", NULL);
 494         tar_filter_config("tar.tar.gz.command", "gzip -cn", NULL);
 495         tar_filter_config("tar.tar.gz.remote", "true", NULL);
 496         git_config(git_tar_config, NULL);
 497         for (i = 0; i < nr_tar_filters; i++) {
 498                 /* omit any filters that never had a command configured */
 499                 if (tar_filters[i]->data)
 500                         register_archiver(tar_filters[i]);
 501         }
 502 }