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