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