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 "streaming.h"
   8 #include "run-command.h"
   9
  10 #define RECORDSIZE      (512)
  11 #define BLOCKSIZE       (RECORDSIZE * 20)
  12
  13 static char block[BLOCKSIZE];
  14 static unsigned long offset;
  15
  16 static int tar_umask = 002;
  17
  18 static int write_tar_filter_archive(const struct archiver *ar,
  19                                     struct archiver_args *args);
  20
  21 /*
  22  * This is the max value that a ustar size header can specify, as it is fixed
  23  * at 11 octal digits. POSIX specifies that we switch to extended headers at
  24  * this size.
  25  *
  26  * Likewise for the mtime (which happens to use a buffer of the same size).
  27  */
  28 #if ULONG_MAX == 0xFFFFFFFF
  29 #define USTAR_MAX_SIZE ULONG_MAX
  30 #define USTAR_MAX_MTIME ULONG_MAX
  31 #else
  32 #define USTAR_MAX_SIZE 077777777777UL
  33 #define USTAR_MAX_MTIME 077777777777UL
  34 #endif
  35
  36 /* writes out the whole block, but only if it is full */
  37 static void write_if_needed(void)
  38 {
  39         if (offset == BLOCKSIZE) {
  40                 write_or_die(1, block, BLOCKSIZE);
  41                 offset = 0;
  42         }
  43 }
  44
  45 /*
  46  * queues up writes, so that all our write(2) calls write exactly one
  47  * full block; pads writes to RECORDSIZE
  48  */
  49 static void do_write_blocked(const void *data, unsigned long size)
  50 {
  51         const char *buf = data;
  52
  53         if (offset) {
  54                 unsigned long chunk = BLOCKSIZE - offset;
  55                 if (size < chunk)
  56                         chunk = size;
  57                 memcpy(block + offset, buf, chunk);
  58                 size -= chunk;
  59                 offset += chunk;
  60                 buf += chunk;
  61                 write_if_needed();
  62         }
  63         while (size >= BLOCKSIZE) {
  64                 write_or_die(1, buf, BLOCKSIZE);
  65                 size -= BLOCKSIZE;
  66                 buf += BLOCKSIZE;
  67         }
  68         if (size) {
  69                 memcpy(block + offset, buf, size);
  70                 offset += size;
  71         }
  72 }
  73
  74 static void finish_record(void)
  75 {
  76         unsigned long tail;
  77         tail = offset % RECORDSIZE;
  78         if (tail)  {
  79                 memset(block + offset, 0, RECORDSIZE - tail);
  80                 offset += RECORDSIZE - tail;
  81         }
  82         write_if_needed();
  83 }
  84
  85 static void write_blocked(const void *data, unsigned long size)
  86 {
  87         do_write_blocked(data, size);
  88         finish_record();
  89 }
  90
  91 /*
  92  * The end of tar archives is marked by 2*512 nul bytes and after that
  93  * follows the rest of the block (if any).
  94  */
  95 static void write_trailer(void)
  96 {
  97         int tail = BLOCKSIZE - offset;
  98         memset(block + offset, 0, tail);
  99         write_or_die(1, block, BLOCKSIZE);
 100         if (tail < 2 * RECORDSIZE) {
 101                 memset(block, 0, offset);
 102                 write_or_die(1, block, BLOCKSIZE);
 103         }
 104 }
 105
 106 /*
 107  * queues up writes, so that all our write(2) calls write exactly one
 108  * full block; pads writes to RECORDSIZE
 109  */
 110 static int stream_blocked(const unsigned char *sha1)
 111 {
 112         struct git_istream *st;
 113         enum object_type type;
 114         unsigned long sz;
 115         char buf[BLOCKSIZE];
 116         ssize_t readlen;
 117
 118         st = open_istream(sha1, &type, &sz, NULL);
 119         if (!st)
 120                 return error("cannot stream blob %s", sha1_to_hex(sha1));
 121         for (;;) {
 122                 readlen = read_istream(st, buf, sizeof(buf));
 123                 if (readlen <= 0)
 124                         break;
 125                 do_write_blocked(buf, readlen);
 126         }
 127         close_istream(st);
 128         if (!readlen)
 129                 finish_record();
 130         return readlen;
 131 }
 132
 133 /*
 134  * pax extended header records have the format "%u %s=%s\n".  %u contains
 135  * the size of the whole string (including the %u), the first %s is the
 136  * keyword, the second one is the value.  This function constructs such a
 137  * string and appends it to a struct strbuf.
 138  */
 139 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 140                                      const char *value, unsigned int valuelen)
 141 {
 142         int len, tmp;
 143
 144         /* "%u %s=%s\n" */
 145         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 146         for (tmp = len; tmp > 9; tmp /= 10)
 147                 len++;
 148
 149         strbuf_grow(sb, len);
 150         strbuf_addf(sb, "%u %s=", len, keyword);
 151         strbuf_add(sb, value, valuelen);
 152         strbuf_addch(sb, '\n');
 153 }
 154
 155 /*
 156  * Like strbuf_append_ext_header, but for numeric values.
 157  */
 158 static void strbuf_append_ext_header_uint(struct strbuf *sb,
 159                                           const char *keyword,
 160                                           uintmax_t value)
 161 {
 162         char buf[40]; /* big enough for 2^128 in decimal, plus NUL */
 163         int len;
 164
 165         len = xsnprintf(buf, sizeof(buf), "%"PRIuMAX, value);
 166         strbuf_append_ext_header(sb, keyword, buf, len);
 167 }
 168
 169 static unsigned int ustar_header_chksum(const struct ustar_header *header)
 170 {
 171         const unsigned char *p = (const unsigned char *)header;
 172         unsigned int chksum = 0;
 173         while (p < (const unsigned char *)header->chksum)
 174                 chksum += *p++;
 175         chksum += sizeof(header->chksum) * ' ';
 176         p += sizeof(header->chksum);
 177         while (p < (const unsigned char *)header + sizeof(struct ustar_header))
 178                 chksum += *p++;
 179         return chksum;
 180 }
 181
 182 static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
 183 {
 184         size_t i = pathlen;
 185         if (i > 1 && path[i - 1] == '/')
 186                 i--;
 187         if (i > maxlen)
 188                 i = maxlen;
 189         do {
 190                 i--;
 191         } while (i > 0 && path[i] != '/');
 192         return i;
 193 }
 194
 195 static void prepare_header(struct archiver_args *args,
 196                            struct ustar_header *header,
 197                            unsigned int mode, unsigned long size)
 198 {
 199         xsnprintf(header->mode, sizeof(header->mode), "%07o", mode & 07777);
 200         xsnprintf(header->size, sizeof(header->size), "%011lo", S_ISREG(mode) ? size : 0);
 201         xsnprintf(header->mtime, sizeof(header->mtime), "%011lo", (unsigned long) args->time);
 202
 203         xsnprintf(header->uid, sizeof(header->uid), "%07o", 0);
 204         xsnprintf(header->gid, sizeof(header->gid), "%07o", 0);
 205         strlcpy(header->uname, "root", sizeof(header->uname));
 206         strlcpy(header->gname, "root", sizeof(header->gname));
 207         xsnprintf(header->devmajor, sizeof(header->devmajor), "%07o", 0);
 208         xsnprintf(header->devminor, sizeof(header->devminor), "%07o", 0);
 209
 210         memcpy(header->magic, "ustar", 6);
 211         memcpy(header->version, "00", 2);
 212
 213         xsnprintf(header->chksum, sizeof(header->chksum), "%07o", ustar_header_chksum(header));
 214 }
 215
 216 static int write_extended_header(struct archiver_args *args,
 217                                  const unsigned char *sha1,
 218                                  const void *buffer, unsigned long size)
 219 {
 220         struct ustar_header header;
 221         unsigned int mode;
 222         memset(&header, 0, sizeof(header));
 223         *header.typeflag = TYPEFLAG_EXT_HEADER;
 224         mode = 0100666;
 225         xsnprintf(header.name, sizeof(header.name), "%s.paxheader", sha1_to_hex(sha1));
 226         prepare_header(args, &header, mode, size);
 227         write_blocked(&header, sizeof(header));
 228         write_blocked(buffer, size);
 229         return 0;
 230 }
 231
 232 static int write_tar_entry(struct archiver_args *args,
 233                            const unsigned char *sha1,
 234                            const char *path, size_t pathlen,
 235                            unsigned int mode)
 236 {
 237         struct ustar_header header;
 238         struct strbuf ext_header = STRBUF_INIT;
 239         unsigned int old_mode = mode;
 240         unsigned long size, size_in_header;
 241         void *buffer;
 242         int err = 0;
 243
 244         memset(&header, 0, sizeof(header));
 245
 246         if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 247                 *header.typeflag = TYPEFLAG_DIR;
 248                 mode = (mode | 0777) & ~tar_umask;
 249         } else if (S_ISLNK(mode)) {
 250                 *header.typeflag = TYPEFLAG_LNK;
 251                 mode |= 0777;
 252         } else if (S_ISREG(mode)) {
 253                 *header.typeflag = TYPEFLAG_REG;
 254                 mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 255         } else {
 256                 return error("unsupported file mode: 0%o (SHA1: %s)",
 257                              mode, sha1_to_hex(sha1));
 258         }
 259         if (pathlen > sizeof(header.name)) {
 260                 size_t plen = get_path_prefix(path, pathlen,
 261                                               sizeof(header.prefix));
 262                 size_t rest = pathlen - plen - 1;
 263                 if (plen > 0 && rest <= sizeof(header.name)) {
 264                         memcpy(header.prefix, path, plen);
 265                         memcpy(header.name, path + plen + 1, rest);
 266                 } else {
 267                         xsnprintf(header.name, sizeof(header.name), "%s.data",
 268                                   sha1_to_hex(sha1));
 269                         strbuf_append_ext_header(&ext_header, "path",
 270                                                  path, pathlen);
 271                 }
 272         } else
 273                 memcpy(header.name, path, pathlen);
 274
 275         if (S_ISREG(mode) && !args->convert &&
 276             sha1_object_info(sha1, &size) == OBJ_BLOB &&
 277             size > big_file_threshold)
 278                 buffer = NULL;
 279         else if (S_ISLNK(mode) || S_ISREG(mode)) {
 280                 enum object_type type;
 281                 buffer = sha1_file_to_archive(args, path, sha1, old_mode, &type, &size);
 282                 if (!buffer)
 283                         return error("cannot read %s", sha1_to_hex(sha1));
 284         } else {
 285                 buffer = NULL;
 286                 size = 0;
 287         }
 288
 289         if (S_ISLNK(mode)) {
 290                 if (size > sizeof(header.linkname)) {
 291                         xsnprintf(header.linkname, sizeof(header.linkname),
 292                                   "see %s.paxheader", sha1_to_hex(sha1));
 293                         strbuf_append_ext_header(&ext_header, "linkpath",
 294                                                  buffer, size);
 295                 } else
 296                         memcpy(header.linkname, buffer, size);
 297         }
 298
 299         size_in_header = size;
 300         if (S_ISREG(mode) && size > USTAR_MAX_SIZE) {
 301                 size_in_header = 0;
 302                 strbuf_append_ext_header_uint(&ext_header, "size", size);
 303         }
 304
 305         prepare_header(args, &header, mode, size_in_header);
 306
 307         if (ext_header.len > 0) {
 308                 err = write_extended_header(args, sha1, ext_header.buf,
 309                                             ext_header.len);
 310                 if (err) {
 311                         free(buffer);
 312                         return err;
 313                 }
 314         }
 315         strbuf_release(&ext_header);
 316         write_blocked(&header, sizeof(header));
 317         if (S_ISREG(mode) && size > 0) {
 318                 if (buffer)
 319                         write_blocked(buffer, size);
 320                 else
 321                         err = stream_blocked(sha1);
 322         }
 323         free(buffer);
 324         return err;
 325 }
 326
 327 static void write_global_extended_header(struct archiver_args *args)
 328 {
 329         const unsigned char *sha1 = args->commit_sha1;
 330         struct strbuf ext_header = STRBUF_INIT;
 331         struct ustar_header header;
 332         unsigned int mode;
 333
 334         if (sha1)
 335                 strbuf_append_ext_header(&ext_header, "comment",
 336                                          sha1_to_hex(sha1), 40);
 337         if (args->time > USTAR_MAX_MTIME) {
 338                 strbuf_append_ext_header_uint(&ext_header, "mtime",
 339                                               args->time);
 340                 args->time = USTAR_MAX_MTIME;
 341         }
 342
 343         if (!ext_header.len)
 344                 return;
 345
 346         memset(&header, 0, sizeof(header));
 347         *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 348         mode = 0100666;
 349         xsnprintf(header.name, sizeof(header.name), "pax_global_header");
 350         prepare_header(args, &header, mode, ext_header.len);
 351         write_blocked(&header, sizeof(header));
 352         write_blocked(ext_header.buf, ext_header.len);
 353         strbuf_release(&ext_header);
 354 }
 355
 356 static struct archiver **tar_filters;
 357 static int nr_tar_filters;
 358 static int alloc_tar_filters;
 359
 360 static struct archiver *find_tar_filter(const char *name, int len)
 361 {
 362         int i;
 363         for (i = 0; i < nr_tar_filters; i++) {
 364                 struct archiver *ar = tar_filters[i];
 365                 if (!strncmp(ar->name, name, len) && !ar->name[len])
 366                         return ar;
 367         }
 368         return NULL;
 369 }
 370
 371 static int tar_filter_config(const char *var, const char *value, void *data)
 372 {
 373         struct archiver *ar;
 374         const char *name;
 375         const char *type;
 376         int namelen;
 377
 378         if (parse_config_key(var, "tar", &name, &namelen, &type) < 0 || !name)
 379                 return 0;
 380
 381         ar = find_tar_filter(name, namelen);
 382         if (!ar) {
 383                 ar = xcalloc(1, sizeof(*ar));
 384                 ar->name = xmemdupz(name, namelen);
 385                 ar->write_archive = write_tar_filter_archive;
 386                 ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS;
 387                 ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
 388                 tar_filters[nr_tar_filters++] = ar;
 389         }
 390
 391         if (!strcmp(type, "command")) {
 392                 if (!value)
 393                         return config_error_nonbool(var);
 394                 free(ar->data);
 395                 ar->data = xstrdup(value);
 396                 return 0;
 397         }
 398         if (!strcmp(type, "remote")) {
 399                 if (git_config_bool(var, value))
 400                         ar->flags |= ARCHIVER_REMOTE;
 401                 else
 402                         ar->flags &= ~ARCHIVER_REMOTE;
 403                 return 0;
 404         }
 405
 406         return 0;
 407 }
 408
 409 static int git_tar_config(const char *var, const char *value, void *cb)
 410 {
 411         if (!strcmp(var, "tar.umask")) {
 412                 if (value && !strcmp(value, "user")) {
 413                         tar_umask = umask(0);
 414                         umask(tar_umask);
 415                 } else {
 416                         tar_umask = git_config_int(var, value);
 417                 }
 418                 return 0;
 419         }
 420
 421         return tar_filter_config(var, value, cb);
 422 }
 423
 424 static int write_tar_archive(const struct archiver *ar,
 425                              struct archiver_args *args)
 426 {
 427         int err = 0;
 428
 429         write_global_extended_header(args);
 430         err = write_archive_entries(args, write_tar_entry);
 431         if (!err)
 432                 write_trailer();
 433         return err;
 434 }
 435
 436 static int write_tar_filter_archive(const struct archiver *ar,
 437                                     struct archiver_args *args)
 438 {
 439         struct strbuf cmd = STRBUF_INIT;
 440         struct child_process filter = CHILD_PROCESS_INIT;
 441         const char *argv[2];
 442         int r;
 443
 444         if (!ar->data)
 445                 die("BUG: tar-filter archiver called with no filter defined");
 446
 447         strbuf_addstr(&cmd, ar->data);
 448         if (args->compression_level >= 0)
 449                 strbuf_addf(&cmd, " -%d", args->compression_level);
 450
 451         argv[0] = cmd.buf;
 452         argv[1] = NULL;
 453         filter.argv = argv;
 454         filter.use_shell = 1;
 455         filter.in = -1;
 456
 457         if (start_command(&filter) < 0)
 458                 die_errno("unable to start '%s' filter", argv[0]);
 459         close(1);
 460         if (dup2(filter.in, 1) < 0)
 461                 die_errno("unable to redirect descriptor");
 462         close(filter.in);
 463
 464         r = write_tar_archive(ar, args);
 465
 466         close(1);
 467         if (finish_command(&filter) != 0)
 468                 die("'%s' filter reported error", argv[0]);
 469
 470         strbuf_release(&cmd);
 471         return r;
 472 }
 473
 474 static struct archiver tar_archiver = {
 475         "tar",
 476         write_tar_archive,
 477         ARCHIVER_REMOTE
 478 };
 479
 480 void init_tar_archiver(void)
 481 {
 482         int i;
 483         register_archiver(&tar_archiver);
 484
 485         tar_filter_config("tar.tgz.command", "gzip -cn", NULL);
 486         tar_filter_config("tar.tgz.remote", "true", NULL);
 487         tar_filter_config("tar.tar.gz.command", "gzip -cn", NULL);
 488         tar_filter_config("tar.tar.gz.remote", "true", NULL);
 489         git_config(git_tar_config, NULL);
 490         for (i = 0; i < nr_tar_filters; i++) {
 491                 /* omit any filters that never had a command configured */
 492                 if (tar_filters[i]->data)
 493                         register_archiver(tar_filters[i]);
 494         }
 495 }