builtin-tar-tree.c

   1 /*
   2  * Copyright (c) 2005, 2006 Rene Scharfe
   3  */
   4 #include <time.h>
   5 #include "cache.h"
   6 #include "tree-walk.h"
   7 #include "commit.h"
   8 #include "strbuf.h"
   9 #include "tar.h"
  10 #include "builtin.h"
  11 #include "pkt-line.h"
  12
  13 #define RECORDSIZE      (512)
  14 #define BLOCKSIZE       (RECORDSIZE * 20)
  15
  16 static const char tar_tree_usage[] =
  17 "git-tar-tree [--remote=<repo>] <ent> [basedir]";
  18
  19 static char block[BLOCKSIZE];
  20 static unsigned long offset;
  21
  22 static time_t archive_time;
  23 static int tar_umask;
  24
  25 /* tries hard to write, either succeeds or dies in the attempt */
  26 static void reliable_write(const void *data, unsigned long size)
  27 {
  28         const char *buf = data;
  29
  30         while (size > 0) {
  31                 long ret = xwrite(1, buf, size);
  32                 if (ret < 0) {
  33                         if (errno == EPIPE)
  34                                 exit(0);
  35                         die("git-tar-tree: %s", strerror(errno));
  36                 } else if (!ret) {
  37                         die("git-tar-tree: disk full?");
  38                 }
  39                 size -= ret;
  40                 buf += ret;
  41         }
  42 }
  43
  44 /* writes out the whole block, but only if it is full */
  45 static void write_if_needed(void)
  46 {
  47         if (offset == BLOCKSIZE) {
  48                 reliable_write(block, BLOCKSIZE);
  49                 offset = 0;
  50         }
  51 }
  52
  53 /*
  54  * queues up writes, so that all our write(2) calls write exactly one
  55  * full block; pads writes to RECORDSIZE
  56  */
  57 static void write_blocked(const void *data, unsigned long size)
  58 {
  59         const char *buf = data;
  60         unsigned long tail;
  61
  62         if (offset) {
  63                 unsigned long chunk = BLOCKSIZE - offset;
  64                 if (size < chunk)
  65                         chunk = size;
  66                 memcpy(block + offset, buf, chunk);
  67                 size -= chunk;
  68                 offset += chunk;
  69                 buf += chunk;
  70                 write_if_needed();
  71         }
  72         while (size >= BLOCKSIZE) {
  73                 reliable_write(buf, BLOCKSIZE);
  74                 size -= BLOCKSIZE;
  75                 buf += BLOCKSIZE;
  76         }
  77         if (size) {
  78                 memcpy(block + offset, buf, size);
  79                 offset += size;
  80         }
  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 /*
  90  * The end of tar archives is marked by 2*512 nul bytes and after that
  91  * follows the rest of the block (if any).
  92  */
  93 static void write_trailer(void)
  94 {
  95         int tail = BLOCKSIZE - offset;
  96         memset(block + offset, 0, tail);
  97         reliable_write(block, BLOCKSIZE);
  98         if (tail < 2 * RECORDSIZE) {
  99                 memset(block, 0, offset);
 100                 reliable_write(block, BLOCKSIZE);
 101         }
 102 }
 103
 104 static void strbuf_append_string(struct strbuf *sb, const char *s)
 105 {
 106         int slen = strlen(s);
 107         int total = sb->len + slen;
 108         if (total > sb->alloc) {
 109                 sb->buf = xrealloc(sb->buf, total);
 110                 sb->alloc = total;
 111         }
 112         memcpy(sb->buf + sb->len, s, slen);
 113         sb->len = total;
 114 }
 115
 116 /*
 117  * pax extended header records have the format "%u %s=%s\n".  %u contains
 118  * the size of the whole string (including the %u), the first %s is the
 119  * keyword, the second one is the value.  This function constructs such a
 120  * string and appends it to a struct strbuf.
 121  */
 122 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 123                                      const char *value, unsigned int valuelen)
 124 {
 125         char *p;
 126         int len, total, tmp;
 127
 128         /* "%u %s=%s\n" */
 129         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 130         for (tmp = len; tmp > 9; tmp /= 10)
 131                 len++;
 132
 133         total = sb->len + len;
 134         if (total > sb->alloc) {
 135                 sb->buf = xrealloc(sb->buf, total);
 136                 sb->alloc = total;
 137         }
 138
 139         p = sb->buf;
 140         p += sprintf(p, "%u %s=", len, keyword);
 141         memcpy(p, value, valuelen);
 142         p += valuelen;
 143         *p = '\n';
 144         sb->len = total;
 145 }
 146
 147 static unsigned int ustar_header_chksum(const struct ustar_header *header)
 148 {
 149         char *p = (char *)header;
 150         unsigned int chksum = 0;
 151         while (p < header->chksum)
 152                 chksum += *p++;
 153         chksum += sizeof(header->chksum) * ' ';
 154         p += sizeof(header->chksum);
 155         while (p < (char *)header + sizeof(struct ustar_header))
 156                 chksum += *p++;
 157         return chksum;
 158 }
 159
 160 static int get_path_prefix(const struct strbuf *path, int maxlen)
 161 {
 162         int i = path->len;
 163         if (i > maxlen)
 164                 i = maxlen;
 165         do {
 166                 i--;
 167         } while (i > 0 && path->buf[i] != '/');
 168         return i;
 169 }
 170
 171 static void write_entry(const unsigned char *sha1, struct strbuf *path,
 172                         unsigned int mode, void *buffer, unsigned long size)
 173 {
 174         struct ustar_header header;
 175         struct strbuf ext_header;
 176
 177         memset(&header, 0, sizeof(header));
 178         ext_header.buf = NULL;
 179         ext_header.len = ext_header.alloc = 0;
 180
 181         if (!sha1) {
 182                 *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 183                 mode = 0100666;
 184                 strcpy(header.name, "pax_global_header");
 185         } else if (!path) {
 186                 *header.typeflag = TYPEFLAG_EXT_HEADER;
 187                 mode = 0100666;
 188                 sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 189         } else {
 190                 if (S_ISDIR(mode)) {
 191                         *header.typeflag = TYPEFLAG_DIR;
 192                         mode = (mode | 0777) & ~tar_umask;
 193                 } else if (S_ISLNK(mode)) {
 194                         *header.typeflag = TYPEFLAG_LNK;
 195                         mode |= 0777;
 196                 } else if (S_ISREG(mode)) {
 197                         *header.typeflag = TYPEFLAG_REG;
 198                         mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 199                 } else {
 200                         error("unsupported file mode: 0%o (SHA1: %s)",
 201                               mode, sha1_to_hex(sha1));
 202                         return;
 203                 }
 204                 if (path->len > sizeof(header.name)) {
 205                         int plen = get_path_prefix(path, sizeof(header.prefix));
 206                         int rest = path->len - plen - 1;
 207                         if (plen > 0 && rest <= sizeof(header.name)) {
 208                                 memcpy(header.prefix, path->buf, plen);
 209                                 memcpy(header.name, path->buf + plen + 1, rest);
 210                         } else {
 211                                 sprintf(header.name, "%s.data",
 212                                         sha1_to_hex(sha1));
 213                                 strbuf_append_ext_header(&ext_header, "path",
 214                                                          path->buf, path->len);
 215                         }
 216                 } else
 217                         memcpy(header.name, path->buf, path->len);
 218         }
 219
 220         if (S_ISLNK(mode) && buffer) {
 221                 if (size > sizeof(header.linkname)) {
 222                         sprintf(header.linkname, "see %s.paxheader",
 223                                 sha1_to_hex(sha1));
 224                         strbuf_append_ext_header(&ext_header, "linkpath",
 225                                                  buffer, size);
 226                 } else
 227                         memcpy(header.linkname, buffer, size);
 228         }
 229
 230         sprintf(header.mode, "%07o", mode & 07777);
 231         sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 232         sprintf(header.mtime, "%011lo", archive_time);
 233
 234         /* XXX: should we provide more meaningful info here? */
 235         sprintf(header.uid, "%07o", 0);
 236         sprintf(header.gid, "%07o", 0);
 237         strlcpy(header.uname, "git", sizeof(header.uname));
 238         strlcpy(header.gname, "git", sizeof(header.gname));
 239         sprintf(header.devmajor, "%07o", 0);
 240         sprintf(header.devminor, "%07o", 0);
 241
 242         memcpy(header.magic, "ustar", 6);
 243         memcpy(header.version, "00", 2);
 244
 245         sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 246
 247         if (ext_header.len > 0) {
 248                 write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
 249                 free(ext_header.buf);
 250         }
 251         write_blocked(&header, sizeof(header));
 252         if (S_ISREG(mode) && buffer && size > 0)
 253                 write_blocked(buffer, size);
 254 }
 255
 256 static void write_global_extended_header(const unsigned char *sha1)
 257 {
 258         struct strbuf ext_header;
 259         ext_header.buf = NULL;
 260         ext_header.len = ext_header.alloc = 0;
 261         strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 262         write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
 263         free(ext_header.buf);
 264 }
 265
 266 static void traverse_tree(struct tree_desc *tree, struct strbuf *path)
 267 {
 268         int pathlen = path->len;
 269         struct name_entry entry;
 270
 271         while (tree_entry(tree, &entry)) {
 272                 void *eltbuf;
 273                 char elttype[20];
 274                 unsigned long eltsize;
 275
 276                 eltbuf = read_sha1_file(entry.sha1, elttype, &eltsize);
 277                 if (!eltbuf)
 278                         die("cannot read %s", sha1_to_hex(entry.sha1));
 279
 280                 path->len = pathlen;
 281                 strbuf_append_string(path, entry.path);
 282                 if (S_ISDIR(entry.mode))
 283                         strbuf_append_string(path, "/");
 284
 285                 write_entry(entry.sha1, path, entry.mode, eltbuf, eltsize);
 286
 287                 if (S_ISDIR(entry.mode)) {
 288                         struct tree_desc subtree;
 289                         subtree.buf = eltbuf;
 290                         subtree.size = eltsize;
 291                         traverse_tree(&subtree, path);
 292                 }
 293                 free(eltbuf);
 294         }
 295 }
 296
 297 int git_tar_config(const char *var, const char *value)
 298 {
 299         if (!strcmp(var, "tar.umask")) {
 300                 if (!strcmp(value, "user")) {
 301                         tar_umask = umask(0);
 302                         umask(tar_umask);
 303                 } else {
 304                         tar_umask = git_config_int(var, value);
 305                 }
 306                 return 0;
 307         }
 308         return git_default_config(var, value);
 309 }
 310
 311 static int generate_tar(int argc, const char **argv, const char *prefix)
 312 {
 313         unsigned char sha1[20], tree_sha1[20];
 314         struct commit *commit;
 315         struct tree_desc tree;
 316         struct strbuf current_path;
 317         void *buffer;
 318
 319         current_path.buf = xmalloc(PATH_MAX);
 320         current_path.alloc = PATH_MAX;
 321         current_path.len = current_path.eof = 0;
 322
 323         git_config(git_tar_config);
 324
 325         switch (argc) {
 326         case 3:
 327                 strbuf_append_string(&current_path, argv[2]);
 328                 strbuf_append_string(&current_path, "/");
 329                 /* FALLTHROUGH */
 330         case 2:
 331                 if (get_sha1(argv[1], sha1))
 332                         die("Not a valid object name %s", argv[1]);
 333                 break;
 334         default:
 335                 usage(tar_tree_usage);
 336         }
 337
 338         commit = lookup_commit_reference_gently(sha1, 1);
 339         if (commit) {
 340                 write_global_extended_header(commit->object.sha1);
 341                 archive_time = commit->date;
 342         } else
 343                 archive_time = time(NULL);
 344
 345         tree.buf = buffer = read_object_with_reference(sha1, tree_type,
 346                                                        &tree.size, tree_sha1);
 347         if (!tree.buf)
 348                 die("not a reference to a tag, commit or tree object: %s",
 349                     sha1_to_hex(sha1));
 350
 351         if (current_path.len > 0)
 352                 write_entry(tree_sha1, &current_path, 040777, NULL, 0);
 353         traverse_tree(&tree, &current_path);
 354         write_trailer();
 355         free(buffer);
 356         free(current_path.buf);
 357         return 0;
 358 }
 359
 360 static const char *exec = "git-upload-tar";
 361
 362 static int remote_tar(int argc, const char **argv)
 363 {
 364         int fd[2], ret, len;
 365         pid_t pid;
 366         char buf[1024];
 367         char *url;
 368
 369         if (argc < 3 || 4 < argc)
 370                 usage(tar_tree_usage);
 371
 372         /* --remote=<repo> */
 373         url = strdup(argv[1]+9);
 374         pid = git_connect(fd, url, exec);
 375         if (pid < 0)
 376                 return 1;
 377
 378         packet_write(fd[1], "want %s\n", argv[2]);
 379         if (argv[3])
 380                 packet_write(fd[1], "base %s\n", argv[3]);
 381         packet_flush(fd[1]);
 382
 383         len = packet_read_line(fd[0], buf, sizeof(buf));
 384         if (!len)
 385                 die("git-tar-tree: expected ACK/NAK, got EOF");
 386         if (buf[len-1] == '\n')
 387                 buf[--len] = 0;
 388         if (strcmp(buf, "ACK")) {
 389                 if (5 < len && !strncmp(buf, "NACK ", 5))
 390                         die("git-tar-tree: NACK %s", buf + 5);
 391                 die("git-tar-tree: protocol error");
 392         }
 393         /* expect a flush */
 394         len = packet_read_line(fd[0], buf, sizeof(buf));
 395         if (len)
 396                 die("git-tar-tree: expected a flush");
 397
 398         /* Now, start reading from fd[0] and spit it out to stdout */
 399         ret = copy_fd(fd[0], 1);
 400         close(fd[0]);
 401
 402         ret |= finish_connect(pid);
 403         return !!ret;
 404 }
 405
 406 int cmd_tar_tree(int argc, const char **argv, const char *prefix)
 407 {
 408         if (argc < 2)
 409                 usage(tar_tree_usage);
 410         if (!strncmp("--remote=", argv[1], 9))
 411                 return remote_tar(argc, argv);
 412         return generate_tar(argc, argv, prefix);
 413 }
 414
 415 /* ustar header + extended global header content */
 416 #define HEADERSIZE (2 * RECORDSIZE)
 417
 418 int cmd_get_tar_commit_id(int argc, const char **argv, const char *prefix)
 419 {
 420         char buffer[HEADERSIZE];
 421         struct ustar_header *header = (struct ustar_header *)buffer;
 422         char *content = buffer + RECORDSIZE;
 423         ssize_t n;
 424
 425         n = xread(0, buffer, HEADERSIZE);
 426         if (n < HEADERSIZE)
 427                 die("git-get-tar-commit-id: read error");
 428         if (header->typeflag[0] != 'g')
 429                 return 1;
 430         if (memcmp(content, "52 comment=", 11))
 431                 return 1;
 432
 433         n = xwrite(1, content + 11, 41);
 434         if (n < 41)
 435                 die("git-get-tar-commit-id: write error");
 436
 437         return 0;
 438 }