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 /* writes out the whole block, but only if it is full */
  22 static void write_if_needed(void)
  23 {
  24         if (offset == BLOCKSIZE) {
  25                 write_or_die(1, block, BLOCKSIZE);
  26                 offset = 0;
  27         }
  28 }
  29
  30 /*
  31  * queues up writes, so that all our write(2) calls write exactly one
  32  * full block; pads writes to RECORDSIZE
  33  */
  34 static void do_write_blocked(const void *data, unsigned long size)
  35 {
  36         const char *buf = data;
  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 }
  58
  59 static void finish_record(void)
  60 {
  61         unsigned long tail;
  62         tail = offset % RECORDSIZE;
  63         if (tail)  {
  64                 memset(block + offset, 0, RECORDSIZE - tail);
  65                 offset += RECORDSIZE - tail;
  66         }
  67         write_if_needed();
  68 }
  69
  70 static void write_blocked(const void *data, unsigned long size)
  71 {
  72         do_write_blocked(data, size);
  73         finish_record();
  74 }
  75
  76 /*
  77  * The end of tar archives is marked by 2*512 nul bytes and after that
  78  * follows the rest of the block (if any).
  79  */
  80 static void write_trailer(void)
  81 {
  82         int tail = BLOCKSIZE - offset;
  83         memset(block + offset, 0, tail);
  84         write_or_die(1, block, BLOCKSIZE);
  85         if (tail < 2 * RECORDSIZE) {
  86                 memset(block, 0, offset);
  87                 write_or_die(1, block, BLOCKSIZE);
  88         }
  89 }
  90
  91 /*
  92  * queues up writes, so that all our write(2) calls write exactly one
  93  * full block; pads writes to RECORDSIZE
  94  */
  95 static int stream_blocked(const unsigned char *sha1)
  96 {
  97         struct git_istream *st;
  98         enum object_type type;
  99         unsigned long sz;
 100         char buf[BLOCKSIZE];
 101         ssize_t readlen;
 102
 103         st = open_istream(sha1, &type, &sz, NULL);
 104         if (!st)
 105                 return error("cannot stream blob %s", sha1_to_hex(sha1));
 106         for (;;) {
 107                 readlen = read_istream(st, buf, sizeof(buf));
 108                 if (readlen <= 0)
 109                         break;
 110                 do_write_blocked(buf, readlen);
 111         }
 112         close_istream(st);
 113         if (!readlen)
 114                 finish_record();
 115         return readlen;
 116 }
 117
 118 /*
 119  * pax extended header records have the format "%u %s=%s\n".  %u contains
 120  * the size of the whole string (including the %u), the first %s is the
 121  * keyword, the second one is the value.  This function constructs such a
 122  * string and appends it to a struct strbuf.
 123  */
 124 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 125                                      const char *value, unsigned int valuelen)
 126 {
 127         int len, tmp;
 128
 129         /* "%u %s=%s\n" */
 130         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 131         for (tmp = len; tmp > 9; tmp /= 10)
 132                 len++;
 133
 134         strbuf_grow(sb, len);
 135         strbuf_addf(sb, "%u %s=", len, keyword);
 136         strbuf_add(sb, value, valuelen);
 137         strbuf_addch(sb, '\n');
 138 }
 139
 140 static unsigned int ustar_header_chksum(const struct ustar_header *header)
 141 {
 142         const unsigned char *p = (const unsigned char *)header;
 143         unsigned int chksum = 0;
 144         while (p < (const unsigned char *)header->chksum)
 145                 chksum += *p++;
 146         chksum += sizeof(header->chksum) * ' ';
 147         p += sizeof(header->chksum);
 148         while (p < (const unsigned char *)header + sizeof(struct ustar_header))
 149                 chksum += *p++;
 150         return chksum;
 151 }
 152
 153 static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
 154 {
 155         size_t i = pathlen;
 156         if (i > 1 && path[i - 1] == '/')
 157                 i--;
 158         if (i > maxlen)
 159                 i = maxlen;
 160         do {
 161                 i--;
 162         } while (i > 0 && path[i] != '/');
 163         return i;
 164 }
 165
 166 static void prepare_header(struct archiver_args *args,
 167                            struct ustar_header *header,
 168                            unsigned int mode, unsigned long size)
 169 {
 170         sprintf(header->mode, "%07o", mode & 07777);
 171         sprintf(header->size, "%011lo", S_ISREG(mode) ? size : 0);
 172         sprintf(header->mtime, "%011lo", (unsigned long) args->time);
 173
 174         sprintf(header->uid, "%07o", 0);
 175         sprintf(header->gid, "%07o", 0);
 176         strlcpy(header->uname, "root", sizeof(header->uname));
 177         strlcpy(header->gname, "root", sizeof(header->gname));
 178         sprintf(header->devmajor, "%07o", 0);
 179         sprintf(header->devminor, "%07o", 0);
 180
 181         memcpy(header->magic, "ustar", 6);
 182         memcpy(header->version, "00", 2);
 183
 184         sprintf(header->chksum, "%07o", ustar_header_chksum(header));
 185 }
 186
 187 static int write_extended_header(struct archiver_args *args,
 188                                  const unsigned char *sha1,
 189                                  const void *buffer, unsigned long size)
 190 {
 191         struct ustar_header header;
 192         unsigned int mode;
 193         memset(&header, 0, sizeof(header));
 194         *header.typeflag = TYPEFLAG_EXT_HEADER;
 195         mode = 0100666;
 196         sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 197         prepare_header(args, &header, mode, size);
 198         write_blocked(&header, sizeof(header));
 199         write_blocked(buffer, size);
 200         return 0;
 201 }
 202
 203 static int write_tar_entry(struct archiver_args *args,
 204                            const unsigned char *sha1,
 205                            const char *path, size_t pathlen,
 206                            unsigned int mode)
 207 {
 208         struct ustar_header header;
 209         struct strbuf ext_header = STRBUF_INIT;
 210         unsigned int old_mode = mode;
 211         unsigned long size;
 212         void *buffer;
 213         int err = 0;
 214
 215         memset(&header, 0, sizeof(header));
 216
 217         if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 218                 *header.typeflag = TYPEFLAG_DIR;
 219                 mode = (mode | 0777) & ~tar_umask;
 220         } else if (S_ISLNK(mode)) {
 221                 *header.typeflag = TYPEFLAG_LNK;
 222                 mode |= 0777;
 223         } else if (S_ISREG(mode)) {
 224                 *header.typeflag = TYPEFLAG_REG;
 225                 mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 226         } else {
 227                 return error("unsupported file mode: 0%o (SHA1: %s)",
 228                              mode, sha1_to_hex(sha1));
 229         }
 230         if (pathlen > sizeof(header.name)) {
 231                 size_t plen = get_path_prefix(path, pathlen,
 232                                               sizeof(header.prefix));
 233                 size_t rest = pathlen - plen - 1;
 234                 if (plen > 0 && rest <= sizeof(header.name)) {
 235                         memcpy(header.prefix, path, plen);
 236                                 memcpy(header.name, path + plen + 1, rest);
 237                 } else {
 238                         sprintf(header.name, "%s.data",
 239                                 sha1_to_hex(sha1));
 240                         strbuf_append_ext_header(&ext_header, "path",
 241                                                  path, pathlen);
 242                 }
 243         } else
 244                 memcpy(header.name, path, pathlen);
 245
 246         if (S_ISREG(mode) && !args->convert &&
 247             sha1_object_info(sha1, &size) == OBJ_BLOB &&
 248             size > big_file_threshold)
 249                 buffer = NULL;
 250         else if (S_ISLNK(mode) || S_ISREG(mode)) {
 251                 enum object_type type;
 252                 buffer = sha1_file_to_archive(args, path, sha1, old_mode, &type, &size);
 253                 if (!buffer)
 254                         return error("cannot read %s", sha1_to_hex(sha1));
 255         } else {
 256                 buffer = NULL;
 257                 size = 0;
 258         }
 259
 260         if (S_ISLNK(mode)) {
 261                 if (size > sizeof(header.linkname)) {
 262                         sprintf(header.linkname, "see %s.paxheader",
 263                                 sha1_to_hex(sha1));
 264                         strbuf_append_ext_header(&ext_header, "linkpath",
 265                                                  buffer, size);
 266                 } else
 267                         memcpy(header.linkname, buffer, size);
 268         }
 269
 270         prepare_header(args, &header, mode, size);
 271
 272         if (ext_header.len > 0) {
 273                 err = write_extended_header(args, sha1, ext_header.buf,
 274                                             ext_header.len);
 275                 if (err) {
 276                         free(buffer);
 277                         return err;
 278                 }
 279         }
 280         strbuf_release(&ext_header);
 281         write_blocked(&header, sizeof(header));
 282         if (S_ISREG(mode) && size > 0) {
 283                 if (buffer)
 284                         write_blocked(buffer, size);
 285                 else
 286                         err = stream_blocked(sha1);
 287         }
 288         free(buffer);
 289         return err;
 290 }
 291
 292 static int write_global_extended_header(struct archiver_args *args)
 293 {
 294         const unsigned char *sha1 = args->commit_sha1;
 295         struct strbuf ext_header = STRBUF_INIT;
 296         struct ustar_header header;
 297         unsigned int mode;
 298         int err = 0;
 299
 300         strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 301         memset(&header, 0, sizeof(header));
 302         *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 303         mode = 0100666;
 304         strcpy(header.name, "pax_global_header");
 305         prepare_header(args, &header, mode, ext_header.len);
 306         write_blocked(&header, sizeof(header));
 307         write_blocked(ext_header.buf, ext_header.len);
 308         strbuf_release(&ext_header);
 309         return err;
 310 }
 311
 312 static struct archiver **tar_filters;
 313 static int nr_tar_filters;
 314 static int alloc_tar_filters;
 315
 316 static struct archiver *find_tar_filter(const char *name, int len)
 317 {
 318         int i;
 319         for (i = 0; i < nr_tar_filters; i++) {
 320                 struct archiver *ar = tar_filters[i];
 321                 if (!strncmp(ar->name, name, len) && !ar->name[len])
 322                         return ar;
 323         }
 324         return NULL;
 325 }
 326
 327 static int tar_filter_config(const char *var, const char *value, void *data)
 328 {
 329         struct archiver *ar;
 330         const char *dot;
 331         const char *name;
 332         const char *type;
 333         int namelen;
 334
 335         if (prefixcmp(var, "tar."))
 336                 return 0;
 337         dot = strrchr(var, '.');
 338         if (dot == var + 9)
 339                 return 0;
 340
 341         name = var + 4;
 342         namelen = dot - name;
 343         type = dot + 1;
 344
 345         ar = find_tar_filter(name, namelen);
 346         if (!ar) {
 347                 ar = xcalloc(1, sizeof(*ar));
 348                 ar->name = xmemdupz(name, namelen);
 349                 ar->write_archive = write_tar_filter_archive;
 350                 ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS;
 351                 ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
 352                 tar_filters[nr_tar_filters++] = ar;
 353         }
 354
 355         if (!strcmp(type, "command")) {
 356                 if (!value)
 357                         return config_error_nonbool(var);
 358                 free(ar->data);
 359                 ar->data = xstrdup(value);
 360                 return 0;
 361         }
 362         if (!strcmp(type, "remote")) {
 363                 if (git_config_bool(var, value))
 364                         ar->flags |= ARCHIVER_REMOTE;
 365                 else
 366                         ar->flags &= ~ARCHIVER_REMOTE;
 367                 return 0;
 368         }
 369
 370         return 0;
 371 }
 372
 373 static int git_tar_config(const char *var, const char *value, void *cb)
 374 {
 375         if (!strcmp(var, "tar.umask")) {
 376                 if (value && !strcmp(value, "user")) {
 377                         tar_umask = umask(0);
 378                         umask(tar_umask);
 379                 } else {
 380                         tar_umask = git_config_int(var, value);
 381                 }
 382                 return 0;
 383         }
 384
 385         return tar_filter_config(var, value, cb);
 386 }
 387
 388 static int write_tar_archive(const struct archiver *ar,
 389                              struct archiver_args *args)
 390 {
 391         int err = 0;
 392
 393         if (args->commit_sha1)
 394                 err = write_global_extended_header(args);
 395         if (!err)
 396                 err = write_archive_entries(args, write_tar_entry);
 397         if (!err)
 398                 write_trailer();
 399         return err;
 400 }
 401
 402 static int write_tar_filter_archive(const struct archiver *ar,
 403                                     struct archiver_args *args)
 404 {
 405         struct strbuf cmd = STRBUF_INIT;
 406         struct child_process filter;
 407         const char *argv[2];
 408         int r;
 409
 410         if (!ar->data)
 411                 die("BUG: tar-filter archiver called with no filter defined");
 412
 413         strbuf_addstr(&cmd, ar->data);
 414         if (args->compression_level >= 0)
 415                 strbuf_addf(&cmd, " -%d", args->compression_level);
 416
 417         memset(&filter, 0, sizeof(filter));
 418         argv[0] = cmd.buf;
 419         argv[1] = NULL;
 420         filter.argv = argv;
 421         filter.use_shell = 1;
 422         filter.in = -1;
 423
 424         if (start_command(&filter) < 0)
 425                 die_errno("unable to start '%s' filter", argv[0]);
 426         close(1);
 427         if (dup2(filter.in, 1) < 0)
 428                 die_errno("unable to redirect descriptor");
 429         close(filter.in);
 430
 431         r = write_tar_archive(ar, args);
 432
 433         close(1);
 434         if (finish_command(&filter) != 0)
 435                 die("'%s' filter reported error", argv[0]);
 436
 437         strbuf_release(&cmd);
 438         return r;
 439 }
 440
 441 static struct archiver tar_archiver = {
 442         "tar",
 443         write_tar_archive,
 444         ARCHIVER_REMOTE
 445 };
 446
 447 void init_tar_archiver(void)
 448 {
 449         int i;
 450         register_archiver(&tar_archiver);
 451
 452         tar_filter_config("tar.tgz.command", "gzip -cn", NULL);
 453         tar_filter_config("tar.tgz.remote", "true", NULL);
 454         tar_filter_config("tar.tar.gz.command", "gzip -cn", NULL);
 455         tar_filter_config("tar.tar.gz.remote", "true", NULL);
 456         git_config(git_tar_config, NULL);
 457         for (i = 0; i < nr_tar_filters; i++) {
 458                 /* omit any filters that never had a command configured */
 459                 if (tar_filters[i]->data)
 460                         register_archiver(tar_filters[i]);
 461         }
 462 }