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 "streaming.h"
   9 #include "run-command.h"
  10
  11 #define RECORDSIZE      (512)
  12 #define BLOCKSIZE       (RECORDSIZE * 20)
  13
  14 static char block[BLOCKSIZE];
  15 static unsigned long offset;
  16
  17 static int tar_umask = 002;
  18
  19 static int write_tar_filter_archive(const struct archiver *ar,
  20                                     struct archiver_args *args);
  21
  22 /*
  23  * This is the max value that a ustar size header can specify, as it is fixed
  24  * at 11 octal digits. POSIX specifies that we switch to extended headers at
  25  * this size.
  26  *
  27  * Likewise for the mtime (which happens to use a buffer of the same size).
  28  */
  29 #if ULONG_MAX == 0xFFFFFFFF
  30 #define USTAR_MAX_SIZE ULONG_MAX
  31 #else
  32 #define USTAR_MAX_SIZE 077777777777UL
  33 #endif
  34 #if TIME_MAX == 0xFFFFFFFF
  35 #define USTAR_MAX_MTIME TIME_MAX
  36 #else
  37 #define USTAR_MAX_MTIME 077777777777ULL
  38 #endif
  39
  40 /* writes out the whole block, but only if it is full */
  41 static void write_if_needed(void)
  42 {
  43         if (offset == BLOCKSIZE) {
  44                 write_or_die(1, block, BLOCKSIZE);
  45                 offset = 0;
  46         }
  47 }
  48
  49 /*
  50  * queues up writes, so that all our write(2) calls write exactly one
  51  * full block; pads writes to RECORDSIZE
  52  */
  53 static void do_write_blocked(const void *data, unsigned long size)
  54 {
  55         const char *buf = data;
  56
  57         if (offset) {
  58                 unsigned long chunk = BLOCKSIZE - offset;
  59                 if (size < chunk)
  60                         chunk = size;
  61                 memcpy(block + offset, buf, chunk);
  62                 size -= chunk;
  63                 offset += chunk;
  64                 buf += chunk;
  65                 write_if_needed();
  66         }
  67         while (size >= BLOCKSIZE) {
  68                 write_or_die(1, buf, BLOCKSIZE);
  69                 size -= BLOCKSIZE;
  70                 buf += BLOCKSIZE;
  71         }
  72         if (size) {
  73                 memcpy(block + offset, buf, size);
  74                 offset += size;
  75         }
  76 }
  77
  78 static void finish_record(void)
  79 {
  80         unsigned long tail;
  81         tail = offset % RECORDSIZE;
  82         if (tail)  {
  83                 memset(block + offset, 0, RECORDSIZE - tail);
  84                 offset += RECORDSIZE - tail;
  85         }
  86         write_if_needed();
  87 }
  88
  89 static void write_blocked(const void *data, unsigned long size)
  90 {
  91         do_write_blocked(data, size);
  92         finish_record();
  93 }
  94
  95 /*
  96  * The end of tar archives is marked by 2*512 nul bytes and after that
  97  * follows the rest of the block (if any).
  98  */
  99 static void write_trailer(void)
 100 {
 101         int tail = BLOCKSIZE - offset;
 102         memset(block + offset, 0, tail);
 103         write_or_die(1, block, BLOCKSIZE);
 104         if (tail < 2 * RECORDSIZE) {
 105                 memset(block, 0, offset);
 106                 write_or_die(1, block, BLOCKSIZE);
 107         }
 108 }
 109
 110 /*
 111  * queues up writes, so that all our write(2) calls write exactly one
 112  * full block; pads writes to RECORDSIZE
 113  */
 114 static int stream_blocked(const unsigned char *sha1)
 115 {
 116         struct git_istream *st;
 117         enum object_type type;
 118         unsigned long sz;
 119         char buf[BLOCKSIZE];
 120         ssize_t readlen;
 121
 122         st = open_istream(sha1, &type, &sz, NULL);
 123         if (!st)
 124                 return error("cannot stream blob %s", sha1_to_hex(sha1));
 125         for (;;) {
 126                 readlen = read_istream(st, buf, sizeof(buf));
 127                 if (readlen <= 0)
 128                         break;
 129                 do_write_blocked(buf, readlen);
 130         }
 131         close_istream(st);
 132         if (!readlen)
 133                 finish_record();
 134         return readlen;
 135 }
 136
 137 /*
 138  * pax extended header records have the format "%u %s=%s\n".  %u contains
 139  * the size of the whole string (including the %u), the first %s is the
 140  * keyword, the second one is the value.  This function constructs such a
 141  * string and appends it to a struct strbuf.
 142  */
 143 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 144                                      const char *value, unsigned int valuelen)
 145 {
 146         int len, tmp;
 147
 148         /* "%u %s=%s\n" */
 149         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 150         for (tmp = len; tmp > 9; tmp /= 10)
 151                 len++;
 152
 153         strbuf_grow(sb, len);
 154         strbuf_addf(sb, "%u %s=", len, keyword);
 155         strbuf_add(sb, value, valuelen);
 156         strbuf_addch(sb, '\n');
 157 }
 158
 159 /*
 160  * Like strbuf_append_ext_header, but for numeric values.
 161  */
 162 static void strbuf_append_ext_header_uint(struct strbuf *sb,
 163                                           const char *keyword,
 164                                           uintmax_t value)
 165 {
 166         char buf[40]; /* big enough for 2^128 in decimal, plus NUL */
 167         int len;
 168
 169         len = xsnprintf(buf, sizeof(buf), "%"PRIuMAX, value);
 170         strbuf_append_ext_header(sb, keyword, buf, len);
 171 }
 172
 173 static unsigned int ustar_header_chksum(const struct ustar_header *header)
 174 {
 175         const unsigned char *p = (const unsigned char *)header;
 176         unsigned int chksum = 0;
 177         while (p < (const unsigned char *)header->chksum)
 178                 chksum += *p++;
 179         chksum += sizeof(header->chksum) * ' ';
 180         p += sizeof(header->chksum);
 181         while (p < (const unsigned char *)header + sizeof(struct ustar_header))
 182                 chksum += *p++;
 183         return chksum;
 184 }
 185
 186 static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
 187 {
 188         size_t i = pathlen;
 189         if (i > 1 && path[i - 1] == '/')
 190                 i--;
 191         if (i > maxlen)
 192                 i = maxlen;
 193         do {
 194                 i--;
 195         } while (i > 0 && path[i] != '/');
 196         return i;
 197 }
 198
 199 static void prepare_header(struct archiver_args *args,
 200                            struct ustar_header *header,
 201                            unsigned int mode, unsigned long size)
 202 {
 203         xsnprintf(header->mode, sizeof(header->mode), "%07o", mode & 07777);
 204         xsnprintf(header->size, sizeof(header->size), "%011lo", S_ISREG(mode) ? size : 0);
 205         xsnprintf(header->mtime, sizeof(header->mtime), "%011lo", (unsigned long) args->time);
 206
 207         xsnprintf(header->uid, sizeof(header->uid), "%07o", 0);
 208         xsnprintf(header->gid, sizeof(header->gid), "%07o", 0);
 209         strlcpy(header->uname, "root", sizeof(header->uname));
 210         strlcpy(header->gname, "root", sizeof(header->gname));
 211         xsnprintf(header->devmajor, sizeof(header->devmajor), "%07o", 0);
 212         xsnprintf(header->devminor, sizeof(header->devminor), "%07o", 0);
 213
 214         memcpy(header->magic, "ustar", 6);
 215         memcpy(header->version, "00", 2);
 216
 217         xsnprintf(header->chksum, sizeof(header->chksum), "%07o", ustar_header_chksum(header));
 218 }
 219
 220 static void write_extended_header(struct archiver_args *args,
 221                                   const unsigned char *sha1,
 222                                   const void *buffer, unsigned long size)
 223 {
 224         struct ustar_header header;
 225         unsigned int mode;
 226         memset(&header, 0, sizeof(header));
 227         *header.typeflag = TYPEFLAG_EXT_HEADER;
 228         mode = 0100666;
 229         xsnprintf(header.name, sizeof(header.name), "%s.paxheader", sha1_to_hex(sha1));
 230         prepare_header(args, &header, mode, size);
 231         write_blocked(&header, sizeof(header));
 232         write_blocked(buffer, size);
 233 }
 234
 235 static int write_tar_entry(struct archiver_args *args,
 236                            const unsigned char *sha1,
 237                            const char *path, size_t pathlen,
 238                            unsigned int mode)
 239 {
 240         struct ustar_header header;
 241         struct strbuf ext_header = STRBUF_INIT;
 242         unsigned int old_mode = mode;
 243         unsigned long size, size_in_header;
 244         void *buffer;
 245         int err = 0;
 246
 247         memset(&header, 0, sizeof(header));
 248
 249         if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 250                 *header.typeflag = TYPEFLAG_DIR;
 251                 mode = (mode | 0777) & ~tar_umask;
 252         } else if (S_ISLNK(mode)) {
 253                 *header.typeflag = TYPEFLAG_LNK;
 254                 mode |= 0777;
 255         } else if (S_ISREG(mode)) {
 256                 *header.typeflag = TYPEFLAG_REG;
 257                 mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 258         } else {
 259                 return error("unsupported file mode: 0%o (SHA1: %s)",
 260                              mode, sha1_to_hex(sha1));
 261         }
 262         if (pathlen > sizeof(header.name)) {
 263                 size_t plen = get_path_prefix(path, pathlen,
 264                                               sizeof(header.prefix));
 265                 size_t rest = pathlen - plen - 1;
 266                 if (plen > 0 && rest <= sizeof(header.name)) {
 267                         memcpy(header.prefix, path, plen);
 268                         memcpy(header.name, path + plen + 1, rest);
 269                 } else {
 270                         xsnprintf(header.name, sizeof(header.name), "%s.data",
 271                                   sha1_to_hex(sha1));
 272                         strbuf_append_ext_header(&ext_header, "path",
 273                                                  path, pathlen);
 274                 }
 275         } else
 276                 memcpy(header.name, path, pathlen);
 277
 278         if (S_ISREG(mode) && !args->convert &&
 279             sha1_object_info(sha1, &size) == OBJ_BLOB &&
 280             size > big_file_threshold)
 281                 buffer = NULL;
 282         else if (S_ISLNK(mode) || S_ISREG(mode)) {
 283                 enum object_type type;
 284                 buffer = sha1_file_to_archive(args, path, sha1, old_mode, &type, &size);
 285                 if (!buffer)
 286                         return error("cannot read %s", sha1_to_hex(sha1));
 287         } else {
 288                 buffer = NULL;
 289                 size = 0;
 290         }
 291
 292         if (S_ISLNK(mode)) {
 293                 if (size > sizeof(header.linkname)) {
 294                         xsnprintf(header.linkname, sizeof(header.linkname),
 295                                   "see %s.paxheader", sha1_to_hex(sha1));
 296                         strbuf_append_ext_header(&ext_header, "linkpath",
 297                                                  buffer, size);
 298                 } else
 299                         memcpy(header.linkname, buffer, size);
 300         }
 301
 302         size_in_header = size;
 303         if (S_ISREG(mode) && size > USTAR_MAX_SIZE) {
 304                 size_in_header = 0;
 305                 strbuf_append_ext_header_uint(&ext_header, "size", size);
 306         }
 307
 308         prepare_header(args, &header, mode, size_in_header);
 309
 310         if (ext_header.len > 0) {
 311                 write_extended_header(args, sha1, ext_header.buf,
 312                                       ext_header.len);
 313         }
 314         strbuf_release(&ext_header);
 315         write_blocked(&header, sizeof(header));
 316         if (S_ISREG(mode) && size > 0) {
 317                 if (buffer)
 318                         write_blocked(buffer, size);
 319                 else
 320                         err = stream_blocked(sha1);
 321         }
 322         free(buffer);
 323         return err;
 324 }
 325
 326 static void write_global_extended_header(struct archiver_args *args)
 327 {
 328         const unsigned char *sha1 = args->commit_sha1;
 329         struct strbuf ext_header = STRBUF_INIT;
 330         struct ustar_header header;
 331         unsigned int mode;
 332
 333         if (sha1)
 334                 strbuf_append_ext_header(&ext_header, "comment",
 335                                          sha1_to_hex(sha1), 40);
 336         if (args->time > USTAR_MAX_MTIME) {
 337                 strbuf_append_ext_header_uint(&ext_header, "mtime",
 338                                               args->time);
 339                 args->time = USTAR_MAX_MTIME;
 340         }
 341
 342         if (!ext_header.len)
 343                 return;
 344
 345         memset(&header, 0, sizeof(header));
 346         *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 347         mode = 0100666;
 348         xsnprintf(header.name, sizeof(header.name), "pax_global_header");
 349         prepare_header(args, &header, mode, ext_header.len);
 350         write_blocked(&header, sizeof(header));
 351         write_blocked(ext_header.buf, ext_header.len);
 352         strbuf_release(&ext_header);
 353 }
 354
 355 static struct archiver **tar_filters;
 356 static int nr_tar_filters;
 357 static int alloc_tar_filters;
 358
 359 static struct archiver *find_tar_filter(const char *name, int len)
 360 {
 361         int i;
 362         for (i = 0; i < nr_tar_filters; i++) {
 363                 struct archiver *ar = tar_filters[i];
 364                 if (!strncmp(ar->name, name, len) && !ar->name[len])
 365                         return ar;
 366         }
 367         return NULL;
 368 }
 369
 370 static int tar_filter_config(const char *var, const char *value, void *data)
 371 {
 372         struct archiver *ar;
 373         const char *name;
 374         const char *type;
 375         int namelen;
 376
 377         if (parse_config_key(var, "tar", &name, &namelen, &type) < 0 || !name)
 378                 return 0;
 379
 380         ar = find_tar_filter(name, namelen);
 381         if (!ar) {
 382                 ar = xcalloc(1, sizeof(*ar));
 383                 ar->name = xmemdupz(name, namelen);
 384                 ar->write_archive = write_tar_filter_archive;
 385                 ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS;
 386                 ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
 387                 tar_filters[nr_tar_filters++] = ar;
 388         }
 389
 390         if (!strcmp(type, "command")) {
 391                 if (!value)
 392                         return config_error_nonbool(var);
 393                 free(ar->data);
 394                 ar->data = xstrdup(value);
 395                 return 0;
 396         }
 397         if (!strcmp(type, "remote")) {
 398                 if (git_config_bool(var, value))
 399                         ar->flags |= ARCHIVER_REMOTE;
 400                 else
 401                         ar->flags &= ~ARCHIVER_REMOTE;
 402                 return 0;
 403         }
 404
 405         return 0;
 406 }
 407
 408 static int git_tar_config(const char *var, const char *value, void *cb)
 409 {
 410         if (!strcmp(var, "tar.umask")) {
 411                 if (value && !strcmp(value, "user")) {
 412                         tar_umask = umask(0);
 413                         umask(tar_umask);
 414                 } else {
 415                         tar_umask = git_config_int(var, value);
 416                 }
 417                 return 0;
 418         }
 419
 420         return tar_filter_config(var, value, cb);
 421 }
 422
 423 static int write_tar_archive(const struct archiver *ar,
 424                              struct archiver_args *args)
 425 {
 426         int err = 0;
 427
 428         write_global_extended_header(args);
 429         err = write_archive_entries(args, write_tar_entry);
 430         if (!err)
 431                 write_trailer();
 432         return err;
 433 }
 434
 435 static int write_tar_filter_archive(const struct archiver *ar,
 436                                     struct archiver_args *args)
 437 {
 438         struct strbuf cmd = STRBUF_INIT;
 439         struct child_process filter = CHILD_PROCESS_INIT;
 440         const char *argv[2];
 441         int r;
 442
 443         if (!ar->data)
 444                 die("BUG: tar-filter archiver called with no filter defined");
 445
 446         strbuf_addstr(&cmd, ar->data);
 447         if (args->compression_level >= 0)
 448                 strbuf_addf(&cmd, " -%d", args->compression_level);
 449
 450         argv[0] = cmd.buf;
 451         argv[1] = NULL;
 452         filter.argv = argv;
 453         filter.use_shell = 1;
 454         filter.in = -1;
 455
 456         if (start_command(&filter) < 0)
 457                 die_errno("unable to start '%s' filter", argv[0]);
 458         close(1);
 459         if (dup2(filter.in, 1) < 0)
 460                 die_errno("unable to redirect descriptor");
 461         close(filter.in);
 462
 463         r = write_tar_archive(ar, args);
 464
 465         close(1);
 466         if (finish_command(&filter) != 0)
 467                 die("'%s' filter reported error", argv[0]);
 468
 469         strbuf_release(&cmd);
 470         return r;
 471 }
 472
 473 static struct archiver tar_archiver = {
 474         "tar",
 475         write_tar_archive,
 476         ARCHIVER_REMOTE
 477 };
 478
 479 void init_tar_archiver(void)
 480 {
 481         int i;
 482         register_archiver(&tar_archiver);
 483
 484         tar_filter_config("tar.tgz.command", "gzip -cn", NULL);
 485         tar_filter_config("tar.tgz.remote", "true", NULL);
 486         tar_filter_config("tar.tar.gz.command", "gzip -cn", NULL);
 487         tar_filter_config("tar.tar.gz.remote", "true", NULL);
 488         git_config(git_tar_config, NULL);
 489         for (i = 0; i < nr_tar_filters; i++) {
 490                 /* omit any filters that never had a command configured */
 491                 if (tar_filters[i]->data)
 492                         register_archiver(tar_filters[i]);
 493         }
 494 }