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
  24 /* tries hard to write, either succeeds or dies in the attempt */
  25 static void reliable_write(const void *data, unsigned long size)
  26 {
  27         const char *buf = data;
  28
  29         while (size > 0) {
  30                 long ret = xwrite(1, buf, size);
  31                 if (ret < 0) {
  32                         if (errno == EPIPE)
  33                                 exit(0);
  34                         die("git-tar-tree: %s", strerror(errno));
  35                 } else if (!ret) {
  36                         die("git-tar-tree: disk full?");
  37                 }
  38                 size -= ret;
  39                 buf += ret;
  40         }
  41 }
  42
  43 /* writes out the whole block, but only if it is full */
  44 static void write_if_needed(void)
  45 {
  46         if (offset == BLOCKSIZE) {
  47                 reliable_write(block, BLOCKSIZE);
  48                 offset = 0;
  49         }
  50 }
  51
  52 /*
  53  * queues up writes, so that all our write(2) calls write exactly one
  54  * full block; pads writes to RECORDSIZE
  55  */
  56 static void write_blocked(const void *data, unsigned long size)
  57 {
  58         const char *buf = data;
  59         unsigned long tail;
  60
  61         if (offset) {
  62                 unsigned long chunk = BLOCKSIZE - offset;
  63                 if (size < chunk)
  64                         chunk = size;
  65                 memcpy(block + offset, buf, chunk);
  66                 size -= chunk;
  67                 offset += chunk;
  68                 buf += chunk;
  69                 write_if_needed();
  70         }
  71         while (size >= BLOCKSIZE) {
  72                 reliable_write(buf, BLOCKSIZE);
  73                 size -= BLOCKSIZE;
  74                 buf += BLOCKSIZE;
  75         }
  76         if (size) {
  77                 memcpy(block + offset, buf, size);
  78                 offset += size;
  79         }
  80         tail = offset % RECORDSIZE;
  81         if (tail)  {
  82                 memset(block + offset, 0, RECORDSIZE - tail);
  83                 offset += RECORDSIZE - tail;
  84         }
  85         write_if_needed();
  86 }
  87
  88 /*
  89  * The end of tar archives is marked by 2*512 nul bytes and after that
  90  * follows the rest of the block (if any).
  91  */
  92 static void write_trailer(void)
  93 {
  94         int tail = BLOCKSIZE - offset;
  95         memset(block + offset, 0, tail);
  96         reliable_write(block, BLOCKSIZE);
  97         if (tail < 2 * RECORDSIZE) {
  98                 memset(block, 0, offset);
  99                 reliable_write(block, BLOCKSIZE);
 100         }
 101 }
 102
 103 static void strbuf_append_string(struct strbuf *sb, const char *s)
 104 {
 105         int slen = strlen(s);
 106         int total = sb->len + slen;
 107         if (total > sb->alloc) {
 108                 sb->buf = xrealloc(sb->buf, total);
 109                 sb->alloc = total;
 110         }
 111         memcpy(sb->buf + sb->len, s, slen);
 112         sb->len = total;
 113 }
 114
 115 /*
 116  * pax extended header records have the format "%u %s=%s\n".  %u contains
 117  * the size of the whole string (including the %u), the first %s is the
 118  * keyword, the second one is the value.  This function constructs such a
 119  * string and appends it to a struct strbuf.
 120  */
 121 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 122                                      const char *value, unsigned int valuelen)
 123 {
 124         char *p;
 125         int len, total, tmp;
 126
 127         /* "%u %s=%s\n" */
 128         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 129         for (tmp = len; tmp > 9; tmp /= 10)
 130                 len++;
 131
 132         total = sb->len + len;
 133         if (total > sb->alloc) {
 134                 sb->buf = xrealloc(sb->buf, total);
 135                 sb->alloc = total;
 136         }
 137
 138         p = sb->buf;
 139         p += sprintf(p, "%u %s=", len, keyword);
 140         memcpy(p, value, valuelen);
 141         p += valuelen;
 142         *p = '\n';
 143         sb->len = total;
 144 }
 145
 146 static unsigned int ustar_header_chksum(const struct ustar_header *header)
 147 {
 148         char *p = (char *)header;
 149         unsigned int chksum = 0;
 150         while (p < header->chksum)
 151                 chksum += *p++;
 152         chksum += sizeof(header->chksum) * ' ';
 153         p += sizeof(header->chksum);
 154         while (p < (char *)header + sizeof(struct ustar_header))
 155                 chksum += *p++;
 156         return chksum;
 157 }
 158
 159 static int get_path_prefix(const struct strbuf *path, int maxlen)
 160 {
 161         int i = path->len;
 162         if (i > maxlen)
 163                 i = maxlen;
 164         do {
 165                 i--;
 166         } while (i > 0 && path->buf[i] != '/');
 167         return i;
 168 }
 169
 170 static void write_entry(const unsigned char *sha1, struct strbuf *path,
 171                         unsigned int mode, void *buffer, unsigned long size)
 172 {
 173         struct ustar_header header;
 174         struct strbuf ext_header;
 175
 176         memset(&header, 0, sizeof(header));
 177         ext_header.buf = NULL;
 178         ext_header.len = ext_header.alloc = 0;
 179
 180         if (!sha1) {
 181                 *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 182                 mode = 0100666;
 183                 strcpy(header.name, "pax_global_header");
 184         } else if (!path) {
 185                 *header.typeflag = TYPEFLAG_EXT_HEADER;
 186                 mode = 0100666;
 187                 sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 188         } else {
 189                 if (S_ISDIR(mode)) {
 190                         *header.typeflag = TYPEFLAG_DIR;
 191                         mode |= 0777;
 192                 } else if (S_ISLNK(mode)) {
 193                         *header.typeflag = TYPEFLAG_LNK;
 194                         mode |= 0777;
 195                 } else if (S_ISREG(mode)) {
 196                         *header.typeflag = TYPEFLAG_REG;
 197                         mode |= (mode & 0100) ? 0777 : 0666;
 198                 } else {
 199                         error("unsupported file mode: 0%o (SHA1: %s)",
 200                               mode, sha1_to_hex(sha1));
 201                         return;
 202                 }
 203                 if (path->len > sizeof(header.name)) {
 204                         int plen = get_path_prefix(path, sizeof(header.prefix));
 205                         int rest = path->len - plen - 1;
 206                         if (plen > 0 && rest <= sizeof(header.name)) {
 207                                 memcpy(header.prefix, path->buf, plen);
 208                                 memcpy(header.name, path->buf + plen + 1, rest);
 209                         } else {
 210                                 sprintf(header.name, "%s.data",
 211                                         sha1_to_hex(sha1));
 212                                 strbuf_append_ext_header(&ext_header, "path",
 213                                                          path->buf, path->len);
 214                         }
 215                 } else
 216                         memcpy(header.name, path->buf, path->len);
 217         }
 218
 219         if (S_ISLNK(mode) && buffer) {
 220                 if (size > sizeof(header.linkname)) {
 221                         sprintf(header.linkname, "see %s.paxheader",
 222                                 sha1_to_hex(sha1));
 223                         strbuf_append_ext_header(&ext_header, "linkpath",
 224                                                  buffer, size);
 225                 } else
 226                         memcpy(header.linkname, buffer, size);
 227         }
 228
 229         sprintf(header.mode, "%07o", mode & 07777);
 230         sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 231         sprintf(header.mtime, "%011lo", archive_time);
 232
 233         /* XXX: should we provide more meaningful info here? */
 234         sprintf(header.uid, "%07o", 0);
 235         sprintf(header.gid, "%07o", 0);
 236         safe_strncpy(header.uname, "git", sizeof(header.uname));
 237         safe_strncpy(header.gname, "git", sizeof(header.gname));
 238         sprintf(header.devmajor, "%07o", 0);
 239         sprintf(header.devminor, "%07o", 0);
 240
 241         memcpy(header.magic, "ustar", 6);
 242         memcpy(header.version, "00", 2);
 243
 244         sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 245
 246         if (ext_header.len > 0) {
 247                 write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
 248                 free(ext_header.buf);
 249         }
 250         write_blocked(&header, sizeof(header));
 251         if (S_ISREG(mode) && buffer && size > 0)
 252                 write_blocked(buffer, size);
 253 }
 254
 255 static void write_global_extended_header(const unsigned char *sha1)
 256 {
 257         struct strbuf ext_header;
 258         ext_header.buf = NULL;
 259         ext_header.len = ext_header.alloc = 0;
 260         strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 261         write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
 262         free(ext_header.buf);
 263 }
 264
 265 static void traverse_tree(struct tree_desc *tree, struct strbuf *path)
 266 {
 267         int pathlen = path->len;
 268         struct name_entry entry;
 269
 270         while (tree_entry(tree, &entry)) {
 271                 void *eltbuf;
 272                 char elttype[20];
 273                 unsigned long eltsize;
 274
 275                 eltbuf = read_sha1_file(entry.sha1, elttype, &eltsize);
 276                 if (!eltbuf)
 277                         die("cannot read %s", sha1_to_hex(entry.sha1));
 278
 279                 path->len = pathlen;
 280                 strbuf_append_string(path, entry.path);
 281                 if (S_ISDIR(entry.mode))
 282                         strbuf_append_string(path, "/");
 283
 284                 write_entry(entry.sha1, path, entry.mode, eltbuf, eltsize);
 285
 286                 if (S_ISDIR(entry.mode)) {
 287                         struct tree_desc subtree;
 288                         subtree.buf = eltbuf;
 289                         subtree.size = eltsize;
 290                         traverse_tree(&subtree, path);
 291                 }
 292                 free(eltbuf);
 293         }
 294 }
 295
 296 static int generate_tar(int argc, const char **argv, char** envp)
 297 {
 298         unsigned char sha1[20], tree_sha1[20];
 299         struct commit *commit;
 300         struct tree_desc tree;
 301         struct strbuf current_path;
 302
 303         current_path.buf = xmalloc(PATH_MAX);
 304         current_path.alloc = PATH_MAX;
 305         current_path.len = current_path.eof = 0;
 306
 307         setup_git_directory();
 308         git_config(git_default_config);
 309
 310         switch (argc) {
 311         case 3:
 312                 strbuf_append_string(&current_path, argv[2]);
 313                 strbuf_append_string(&current_path, "/");
 314                 /* FALLTHROUGH */
 315         case 2:
 316                 if (get_sha1(argv[1], sha1))
 317                         die("Not a valid object name %s", argv[1]);
 318                 break;
 319         default:
 320                 usage(tar_tree_usage);
 321         }
 322
 323         commit = lookup_commit_reference_gently(sha1, 1);
 324         if (commit) {
 325                 write_global_extended_header(commit->object.sha1);
 326                 archive_time = commit->date;
 327         } else
 328                 archive_time = time(NULL);
 329
 330         tree.buf = read_object_with_reference(sha1, tree_type, &tree.size,
 331                                               tree_sha1);
 332         if (!tree.buf)
 333                 die("not a reference to a tag, commit or tree object: %s",
 334                     sha1_to_hex(sha1));
 335
 336         if (current_path.len > 0)
 337                 write_entry(tree_sha1, &current_path, 040777, NULL, 0);
 338         traverse_tree(&tree, &current_path);
 339         write_trailer();
 340         free(current_path.buf);
 341         return 0;
 342 }
 343
 344 static const char *exec = "git-upload-tar";
 345
 346 static int remote_tar(int argc, const char **argv)
 347 {
 348         int fd[2], ret, len;
 349         pid_t pid;
 350         char buf[1024];
 351         char *url;
 352
 353         if (argc < 3 || 4 < argc)
 354                 usage(tar_tree_usage);
 355
 356         /* --remote=<repo> */
 357         url = strdup(argv[1]+9);
 358         pid = git_connect(fd, url, exec);
 359         if (pid < 0)
 360                 return 1;
 361
 362         packet_write(fd[1], "want %s\n", argv[2]);
 363         if (argv[3])
 364                 packet_write(fd[1], "base %s\n", argv[3]);
 365         packet_flush(fd[1]);
 366
 367         len = packet_read_line(fd[0], buf, sizeof(buf));
 368         if (!len)
 369                 die("git-tar-tree: expected ACK/NAK, got EOF");
 370         if (buf[len-1] == '\n')
 371                 buf[--len] = 0;
 372         if (strcmp(buf, "ACK")) {
 373                 if (5 < len && !strncmp(buf, "NACK ", 5))
 374                         die("git-tar-tree: NACK %s", buf + 5);
 375                 die("git-tar-tree: protocol error");
 376         }
 377         /* expect a flush */
 378         len = packet_read_line(fd[0], buf, sizeof(buf));
 379         if (len)
 380                 die("git-tar-tree: expected a flush");
 381
 382         /* Now, start reading from fd[0] and spit it out to stdout */
 383         ret = copy_fd(fd[0], 1);
 384         close(fd[0]);
 385
 386         ret |= finish_connect(pid);
 387         return !!ret;
 388 }
 389
 390 int cmd_tar_tree(int argc, const char **argv, char **envp)
 391 {
 392         if (argc < 2)
 393                 usage(tar_tree_usage);
 394         if (!strncmp("--remote=", argv[1], 9))
 395                 return remote_tar(argc, argv);
 396         return generate_tar(argc, argv, envp);
 397 }
 398
 399 /* ustar header + extended global header content */
 400 #define HEADERSIZE (2 * RECORDSIZE)
 401
 402 int cmd_get_tar_commit_id(int argc, const char **argv, char **envp)
 403 {
 404         char buffer[HEADERSIZE];
 405         struct ustar_header *header = (struct ustar_header *)buffer;
 406         char *content = buffer + RECORDSIZE;
 407         ssize_t n;
 408
 409         n = xread(0, buffer, HEADERSIZE);
 410         if (n < HEADERSIZE)
 411                 die("git-get-tar-commit-id: read error");
 412         if (header->typeflag[0] != 'g')
 413                 return 1;
 414         if (memcmp(content, "52 comment=", 11))
 415                 return 1;
 416
 417         n = xwrite(1, content + 11, 41);
 418         if (n < 41)
 419                 die("git-get-tar-commit-id: write error");
 420
 421         return 0;
 422 }