tar-tree.c

   1 /*
   2  * Copyright (c) 2005 Rene Scharfe
   3  */
   4 #include <time.h>
   5 #include "cache.h"
   6 #include "tree.h"
   7
   8 #define RECORDSIZE      (512)
   9 #define BLOCKSIZE       (RECORDSIZE * 20)
  10
  11 #define TYPEFLAG_AUTO           '\0'
  12 #define TYPEFLAG_REG            '0'
  13 #define TYPEFLAG_LNK            '2'
  14 #define TYPEFLAG_DIR            '5'
  15 #define TYPEFLAG_GLOBAL_HEADER  'g'
  16 #define TYPEFLAG_EXT_HEADER     'x'
  17
  18 #define EXT_HEADER_PATH         1
  19 #define EXT_HEADER_LINKPATH     2
  20
  21 static const char tar_tree_usage[] = "git-tar-tree <key> [basedir]";
  22
  23 static char block[BLOCKSIZE];
  24 static unsigned long offset;
  25
  26 static const char *basedir;
  27 static time_t archive_time;
  28
  29 struct path_prefix {
  30         struct path_prefix *prev;
  31         const char *name;
  32 };
  33
  34 /* tries hard to write, either succeeds or dies in the attempt */
  35 static void reliable_write(void *buf, unsigned long size)
  36 {
  37         while (size > 0) {
  38                 long ret = xwrite(1, buf, size);
  39                 if (ret < 0) {
  40                         if (errno == EPIPE)
  41                                 exit(0);
  42                         die("git-tar-tree: %s", strerror(errno));
  43                 } else if (!ret) {
  44                         die("git-tar-tree: disk full?");
  45                 }
  46                 size -= ret;
  47                 buf += ret;
  48         }
  49 }
  50
  51 /* writes out the whole block, but only if it is full */
  52 static void write_if_needed(void)
  53 {
  54         if (offset == BLOCKSIZE) {
  55                 reliable_write(block, BLOCKSIZE);
  56                 offset = 0;
  57         }
  58 }
  59
  60 /* acquire the next record from the buffer; user must call write_if_needed() */
  61 static char *get_record(void)
  62 {
  63         char *p = block + offset;
  64         memset(p, 0, RECORDSIZE);
  65         offset += RECORDSIZE;
  66         return p;
  67 }
  68
  69 /*
  70  * The end of tar archives is marked by 1024 nul bytes and after that
  71  * follows the rest of the block (if any).
  72  */
  73 static void write_trailer(void)
  74 {
  75         get_record();
  76         write_if_needed();
  77         get_record();
  78         write_if_needed();
  79         while (offset) {
  80                 get_record();
  81                 write_if_needed();
  82         }
  83 }
  84
  85 /*
  86  * queues up writes, so that all our write(2) calls write exactly one
  87  * full block; pads writes to RECORDSIZE
  88  */
  89 static void write_blocked(void *buf, unsigned long size)
  90 {
  91         unsigned long tail;
  92
  93         if (offset) {
  94                 unsigned long chunk = BLOCKSIZE - offset;
  95                 if (size < chunk)
  96                         chunk = size;
  97                 memcpy(block + offset, buf, chunk);
  98                 size -= chunk;
  99                 offset += chunk;
 100                 buf += chunk;
 101                 write_if_needed();
 102         }
 103         while (size >= BLOCKSIZE) {
 104                 reliable_write(buf, BLOCKSIZE);
 105                 size -= BLOCKSIZE;
 106                 buf += BLOCKSIZE;
 107         }
 108         if (size) {
 109                 memcpy(block + offset, buf, size);
 110                 buf += size;
 111                 offset += size;
 112         }
 113         tail = offset % RECORDSIZE;
 114         if (tail)  {
 115                 memset(block + offset, 0, RECORDSIZE - tail);
 116                 offset += RECORDSIZE - tail;
 117         }
 118         write_if_needed();
 119 }
 120
 121 static void append_string(char **p, const char *s)
 122 {
 123         unsigned int len = strlen(s);
 124         memcpy(*p, s, len);
 125         *p += len;
 126 }
 127
 128 static void append_char(char **p, char c)
 129 {
 130         **p = c;
 131         *p += 1;
 132 }
 133
 134 static void append_path_prefix(char **buffer, struct path_prefix *prefix)
 135 {
 136         if (!prefix)
 137                 return;
 138         append_path_prefix(buffer, prefix->prev);
 139         append_string(buffer, prefix->name);
 140         append_char(buffer, '/');
 141 }
 142
 143 static unsigned int path_prefix_len(struct path_prefix *prefix)
 144 {
 145         if (!prefix)
 146                 return 0;
 147         return path_prefix_len(prefix->prev) + strlen(prefix->name) + 1;
 148 }
 149
 150 static void append_path(char **p, int is_dir, const char *basepath,
 151                         struct path_prefix *prefix, const char *path)
 152 {
 153         if (basepath) {
 154                 append_string(p, basepath);
 155                 append_char(p, '/');
 156         }
 157         append_path_prefix(p, prefix);
 158         append_string(p, path);
 159         if (is_dir)
 160                 append_char(p, '/');
 161 }
 162
 163 static unsigned int path_len(int is_dir, const char *basepath,
 164                              struct path_prefix *prefix, const char *path)
 165 {
 166         unsigned int len = 0;
 167         if (basepath)
 168                 len += strlen(basepath) + 1;
 169         len += path_prefix_len(prefix) + strlen(path);
 170         if (is_dir)
 171                 len++;
 172         return len;
 173 }
 174
 175 static void append_extended_header_prefix(char **p, unsigned int size,
 176                                           const char *keyword)
 177 {
 178         int len = sprintf(*p, "%u %s=", size, keyword);
 179         *p += len;
 180 }
 181
 182 static unsigned int extended_header_len(const char *keyword,
 183                                         unsigned int valuelen)
 184 {
 185         /* "%u %s=%s\n" */
 186         unsigned int len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 187         if (len > 9)
 188                 len++;
 189         if (len > 99)
 190                 len++;
 191         return len;
 192 }
 193
 194 static void append_extended_header(char **p, const char *keyword,
 195                                    const char *value, unsigned int len)
 196 {
 197         unsigned int size = extended_header_len(keyword, len);
 198         append_extended_header_prefix(p, size, keyword);
 199         memcpy(*p, value, len);
 200         *p += len;
 201         append_char(p, '\n');
 202 }
 203
 204 static void write_header(const unsigned char *, char, const char *, struct path_prefix *,
 205                          const char *, unsigned int, void *, unsigned long);
 206
 207 /* stores a pax extended header directly in the block buffer */
 208 static void write_extended_header(const char *headerfilename, int is_dir,
 209                                   unsigned int flags, const char *basepath,
 210                                   struct path_prefix *prefix,
 211                                   const char *path, unsigned int namelen,
 212                                   void *content, unsigned int contentsize)
 213 {
 214         char *buffer, *p;
 215         unsigned int pathlen, size, linkpathlen = 0;
 216
 217         size = pathlen = extended_header_len("path", namelen);
 218         if (flags & EXT_HEADER_LINKPATH) {
 219                 linkpathlen = extended_header_len("linkpath", contentsize);
 220                 size += linkpathlen;
 221         }
 222         write_header(NULL, TYPEFLAG_EXT_HEADER, NULL, NULL, headerfilename,
 223                      0100600, NULL, size);
 224
 225         buffer = p = malloc(size);
 226         if (!buffer)
 227                 die("git-tar-tree: %s", strerror(errno));
 228         append_extended_header_prefix(&p, pathlen, "path");
 229         append_path(&p, is_dir, basepath, prefix, path);
 230         append_char(&p, '\n');
 231         if (flags & EXT_HEADER_LINKPATH)
 232                 append_extended_header(&p, "linkpath", content, contentsize);
 233         write_blocked(buffer, size);
 234         free(buffer);
 235 }
 236
 237 static void write_global_extended_header(const unsigned char *sha1)
 238 {
 239         char *p;
 240         unsigned int size;
 241
 242         size = extended_header_len("comment", 40);
 243         write_header(NULL, TYPEFLAG_GLOBAL_HEADER, NULL, NULL,
 244                      "pax_global_header", 0100600, NULL, size);
 245
 246         p = get_record();
 247         append_extended_header(&p, "comment", sha1_to_hex(sha1), 40);
 248         write_if_needed();
 249 }
 250
 251 /* stores a ustar header directly in the block buffer */
 252 static void write_header(const unsigned char *sha1, char typeflag, const char *basepath,
 253                          struct path_prefix *prefix, const char *path,
 254                          unsigned int mode, void *buffer, unsigned long size)
 255 {
 256         unsigned int namelen;
 257         char *header = NULL;
 258         unsigned int checksum = 0;
 259         int i;
 260         unsigned int ext_header = 0;
 261
 262         if (typeflag == TYPEFLAG_AUTO) {
 263                 if (S_ISDIR(mode))
 264                         typeflag = TYPEFLAG_DIR;
 265                 else if (S_ISLNK(mode))
 266                         typeflag = TYPEFLAG_LNK;
 267                 else
 268                         typeflag = TYPEFLAG_REG;
 269         }
 270
 271         namelen = path_len(S_ISDIR(mode), basepath, prefix, path);
 272         if (namelen > 100)
 273                 ext_header |= EXT_HEADER_PATH;
 274         if (typeflag == TYPEFLAG_LNK && size > 100)
 275                 ext_header |= EXT_HEADER_LINKPATH;
 276
 277         /* the extended header must be written before the normal one */
 278         if (ext_header) {
 279                 char headerfilename[51];
 280                 sprintf(headerfilename, "%s.paxheader", sha1_to_hex(sha1));
 281                 write_extended_header(headerfilename, S_ISDIR(mode),
 282                                       ext_header, basepath, prefix, path,
 283                                       namelen, buffer, size);
 284         }
 285
 286         header = get_record();
 287
 288         if (ext_header) {
 289                 sprintf(header, "%s.data", sha1_to_hex(sha1));
 290         } else {
 291                 char *p = header;
 292                 append_path(&p, S_ISDIR(mode), basepath, prefix, path);
 293         }
 294
 295         if (typeflag == TYPEFLAG_LNK) {
 296                 if (ext_header & EXT_HEADER_LINKPATH) {
 297                         sprintf(&header[157], "see %s.paxheader",
 298                                 sha1_to_hex(sha1));
 299                 } else {
 300                         if (buffer)
 301                                 strncpy(&header[157], buffer, size);
 302                 }
 303         }
 304
 305         if (S_ISDIR(mode))
 306                 mode |= 0755;   /* GIT doesn't store permissions of dirs */
 307         if (S_ISLNK(mode))
 308                 mode |= 0777;   /* ... nor of symlinks */
 309         sprintf(&header[100], "%07o", mode & 07777);
 310
 311         /* XXX: should we provide more meaningful info here? */
 312         sprintf(&header[108], "%07o", 0);       /* uid */
 313         sprintf(&header[116], "%07o", 0);       /* gid */
 314         strncpy(&header[265], "git", 31);       /* uname */
 315         strncpy(&header[297], "git", 31);       /* gname */
 316
 317         if (S_ISDIR(mode) || S_ISLNK(mode))
 318                 size = 0;
 319         sprintf(&header[124], "%011lo", size);
 320         sprintf(&header[136], "%011lo", archive_time);
 321
 322         header[156] = typeflag;
 323
 324         memcpy(&header[257], "ustar", 6);
 325         memcpy(&header[263], "00", 2);
 326
 327         sprintf(&header[329], "%07o", 0);       /* devmajor */
 328         sprintf(&header[337], "%07o", 0);       /* devminor */
 329
 330         memset(&header[148], ' ', 8);
 331         for (i = 0; i < RECORDSIZE; i++)
 332                 checksum += header[i];
 333         sprintf(&header[148], "%07o", checksum & 0x1fffff);
 334
 335         write_if_needed();
 336 }
 337
 338 static void traverse_tree(struct tree *tree,
 339                           struct path_prefix *prefix)
 340 {
 341         struct path_prefix this_prefix;
 342         struct tree_entry_list *item;
 343         this_prefix.prev = prefix;
 344
 345         parse_tree(tree);
 346         item = tree->entries;
 347
 348         while (item) {
 349                 void *eltbuf;
 350                 char elttype[20];
 351                 unsigned long eltsize;
 352
 353                 eltbuf = read_sha1_file(item->item.any->sha1,
 354                                         elttype, &eltsize);
 355                 if (!eltbuf)
 356                         die("cannot read %s",
 357                             sha1_to_hex(item->item.any->sha1));
 358                 write_header(item->item.any->sha1, TYPEFLAG_AUTO, basedir,
 359                              prefix, item->name,
 360                              item->mode, eltbuf, eltsize);
 361                 if (item->directory) {
 362                         this_prefix.name = item->name;
 363                         traverse_tree(item->item.tree, &this_prefix);
 364                 } else if (!item->symlink) {
 365                         write_blocked(eltbuf, eltsize);
 366                 }
 367                 free(eltbuf);
 368                 item = item->next;
 369         }
 370 }
 371
 372 /* get commit time from committer line of commit object */
 373 static time_t commit_time(void * buffer, unsigned long size)
 374 {
 375         time_t result = 0;
 376         char *p = buffer;
 377
 378         while (size > 0) {
 379                 char *endp = memchr(p, '\n', size);
 380                 if (!endp || endp == p)
 381                         break;
 382                 *endp = '\0';
 383                 if (endp - p > 10 && !memcmp(p, "committer ", 10)) {
 384                         char *nump = strrchr(p, '>');
 385                         if (!nump)
 386                                 break;
 387                         nump++;
 388                         result = strtoul(nump, &endp, 10);
 389                         if (*endp != ' ')
 390                                 result = 0;
 391                         break;
 392                 }
 393                 size -= endp - p - 1;
 394                 p = endp + 1;
 395         }
 396         return result;
 397 }
 398
 399 int main(int argc, char **argv)
 400 {
 401         unsigned char sha1[20];
 402         unsigned char commit_sha1[20];
 403         void *buffer;
 404         unsigned long size;
 405         struct tree *tree;
 406
 407         setup_git_directory();
 408
 409         switch (argc) {
 410         case 3:
 411                 basedir = argv[2];
 412                 /* FALLTHROUGH */
 413         case 2:
 414                 if (get_sha1(argv[1], sha1) < 0)
 415                         usage(tar_tree_usage);
 416                 break;
 417         default:
 418                 usage(tar_tree_usage);
 419         }
 420
 421         buffer = read_object_with_reference(sha1, "commit", &size, commit_sha1);
 422         if (buffer) {
 423                 write_global_extended_header(commit_sha1);
 424                 archive_time = commit_time(buffer, size);
 425                 free(buffer);
 426         }
 427         tree = parse_tree_indirect(sha1);
 428         if (!tree)
 429                 die("not a reference to a tag, commit or tree object: %s",
 430                     sha1_to_hex(sha1));
 431         if (!archive_time)
 432                 archive_time = time(NULL);
 433         if (basedir)
 434                 write_header((unsigned char *)"0", TYPEFLAG_DIR, NULL, NULL,
 435                         basedir, 040777, NULL, 0);
 436         traverse_tree(tree, NULL);
 437         write_trailer();
 438         return 0;
 439 }