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