Andrew's git - gitweb.git/blob

2be42fe6cbbf2ac835ba08ec7a091005fad8315f
   1/*
   2 * Copyright (c) 2005, 2006 Rene Scharfe
   3 */
   4#include <time.h>
   5#include "cache.h"
   6#include "diff.h"
   7#include "commit.h"
   8#include "strbuf.h"
   9#include "tar.h"
  10
  11#define RECORDSIZE      (512)
  12#define BLOCKSIZE       (RECORDSIZE * 20)
  13
  14#define EXT_HEADER_PATH         1
  15#define EXT_HEADER_LINKPATH     2
  16
  17static const char tar_tree_usage[] = "git-tar-tree <key> [basedir]";
  18
  19static char block[BLOCKSIZE];
  20static unsigned long offset;
  21
  22static const char *basedir;
  23static time_t archive_time;
  24
  25struct path_prefix {
  26        struct path_prefix *prev;
  27        const char *name;
  28};
  29
  30/* tries hard to write, either succeeds or dies in the attempt */
  31static void reliable_write(void *buf, unsigned long size)
  32{
  33        while (size > 0) {
  34                long ret = xwrite(1, buf, size);
  35                if (ret < 0) {
  36                        if (errno == EPIPE)
  37                                exit(0);
  38                        die("git-tar-tree: %s", strerror(errno));
  39                } else if (!ret) {
  40                        die("git-tar-tree: disk full?");
  41                }
  42                size -= ret;
  43                buf += ret;
  44        }
  45}
  46
  47/* writes out the whole block, but only if it is full */
  48static void write_if_needed(void)
  49{
  50        if (offset == BLOCKSIZE) {
  51                reliable_write(block, BLOCKSIZE);
  52                offset = 0;
  53        }
  54}
  55
  56/* acquire the next record from the buffer; user must call write_if_needed() */
  57static char *get_record(void)
  58{
  59        char *p = block + offset;
  60        memset(p, 0, RECORDSIZE);
  61        offset += RECORDSIZE;
  62        return p;
  63}
  64
  65/*
  66 * The end of tar archives is marked by 1024 nul bytes and after that
  67 * follows the rest of the block (if any).
  68 */
  69static void write_trailer(void)
  70{
  71        get_record();
  72        write_if_needed();
  73        get_record();
  74        write_if_needed();
  75        while (offset) {
  76                get_record();
  77                write_if_needed();
  78        }
  79}
  80
  81/*
  82 * queues up writes, so that all our write(2) calls write exactly one
  83 * full block; pads writes to RECORDSIZE
  84 */
  85static void write_blocked(void *buf, unsigned long size)
  86{
  87        unsigned long tail;
  88
  89        if (offset) {
  90                unsigned long chunk = BLOCKSIZE - offset;
  91                if (size < chunk)
  92                        chunk = size;
  93                memcpy(block + offset, buf, chunk);
  94                size -= chunk;
  95                offset += chunk;
  96                buf += chunk;
  97                write_if_needed();
  98        }
  99        while (size >= BLOCKSIZE) {
 100                reliable_write(buf, BLOCKSIZE);
 101                size -= BLOCKSIZE;
 102                buf += BLOCKSIZE;
 103        }
 104        if (size) {
 105                memcpy(block + offset, buf, size);
 106                buf += size;
 107                offset += size;
 108        }
 109        tail = offset % RECORDSIZE;
 110        if (tail)  {
 111                memset(block + offset, 0, RECORDSIZE - tail);
 112                offset += RECORDSIZE - tail;
 113        }
 114        write_if_needed();
 115}
 116
 117static void strbuf_append_string(struct strbuf *sb, const char *s)
 118{
 119        int slen = strlen(s);
 120        int total = sb->len + slen;
 121        if (total > sb->alloc) {
 122                sb->buf = xrealloc(sb->buf, total);
 123                sb->alloc = total;
 124        }
 125        memcpy(sb->buf + sb->len, s, slen);
 126        sb->len = total;
 127}
 128
 129/*
 130 * pax extended header records have the format "%u %s=%s\n".  %u contains
 131 * the size of the whole string (including the %u), the first %s is the
 132 * keyword, the second one is the value.  This function constructs such a
 133 * string and appends it to a struct strbuf.
 134 */
 135static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 136                                     const char *value, unsigned int valuelen)
 137{
 138        char *p;
 139        int len, total, tmp;
 140
 141        /* "%u %s=%s\n" */
 142        len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 143        for (tmp = len; tmp > 9; tmp /= 10)
 144                len++;
 145
 146        total = sb->len + len;
 147        if (total > sb->alloc) {
 148                sb->buf = xrealloc(sb->buf, total);
 149                sb->alloc = total;
 150        }
 151
 152        p = sb->buf;
 153        p += sprintf(p, "%u %s=", len, keyword);
 154        memcpy(p, value, valuelen);
 155        p += valuelen;
 156        *p = '\n';
 157        sb->len = total;
 158}
 159
 160static unsigned int ustar_header_chksum(const struct ustar_header *header)
 161{
 162        char *p = (char *)header;
 163        unsigned int chksum = 0;
 164        while (p < header->chksum)
 165                chksum += *p++;
 166        chksum += sizeof(header->chksum) * ' ';
 167        p += sizeof(header->chksum);
 168        while (p < (char *)header + sizeof(struct ustar_header))
 169                chksum += *p++;
 170        return chksum;
 171}
 172
 173static void write_entry(const unsigned char *sha1, struct strbuf *path,
 174                        unsigned int mode, void *buffer, unsigned long size)
 175{
 176        struct ustar_header header;
 177        struct strbuf ext_header;
 178
 179        memset(&header, 0, sizeof(header));
 180        ext_header.buf = NULL;
 181        ext_header.len = ext_header.alloc = 0;
 182
 183        if (!sha1) {
 184                *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 185                mode = 0100666;
 186                strcpy(header.name, "pax_global_header");
 187        } else if (!path) {
 188                *header.typeflag = TYPEFLAG_EXT_HEADER;
 189                mode = 0100666;
 190                sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 191        } else {
 192                if (S_ISDIR(mode)) {
 193                        *header.typeflag = TYPEFLAG_DIR;
 194                        mode |= 0777;
 195                } else if (S_ISLNK(mode)) {
 196                        *header.typeflag = TYPEFLAG_LNK;
 197                        mode |= 0777;
 198                } else if (S_ISREG(mode)) {
 199                        *header.typeflag = TYPEFLAG_REG;
 200                        mode |= (mode & 0100) ? 0777 : 0666;
 201                } else {
 202                        error("unsupported file mode: 0%o (SHA1: %s)",
 203                              mode, sha1_to_hex(sha1));
 204                        return;
 205                }
 206                if (path->len > sizeof(header.name)) {
 207                        sprintf(header.name, "%s.data", sha1_to_hex(sha1));
 208                        strbuf_append_ext_header(&ext_header, "path",
 209                                                 path->buf, path->len);
 210                } else
 211                        memcpy(header.name, path->buf, path->len);
 212        }
 213
 214        if (S_ISLNK(mode) && buffer) {
 215                if (size > sizeof(header.linkname)) {
 216                        sprintf(header.linkname, "see %s.paxheader",
 217                                sha1_to_hex(sha1));
 218                        strbuf_append_ext_header(&ext_header, "linkpath",
 219                                                 buffer, size);
 220                } else
 221                        memcpy(header.linkname, buffer, size);
 222        }
 223
 224        sprintf(header.mode, "%07o", mode & 07777);
 225        sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 226        sprintf(header.mtime, "%011lo", archive_time);
 227
 228        /* XXX: should we provide more meaningful info here? */
 229        sprintf(header.uid, "%07o", 0);
 230        sprintf(header.gid, "%07o", 0);
 231        strncpy(header.uname, "git", 31);
 232        strncpy(header.gname, "git", 31);
 233        sprintf(header.devmajor, "%07o", 0);
 234        sprintf(header.devminor, "%07o", 0);
 235
 236        memcpy(header.magic, "ustar", 6);
 237        memcpy(header.version, "00", 2);
 238
 239        sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 240
 241        if (ext_header.len > 0) {
 242                write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
 243                free(ext_header.buf);
 244        }
 245        write_blocked(&header, sizeof(header));
 246        if (S_ISREG(mode) && buffer && size > 0)
 247                write_blocked(buffer, size);
 248}
 249
 250static void append_string(char **p, const char *s)
 251{
 252        unsigned int len = strlen(s);
 253        memcpy(*p, s, len);
 254        *p += len;
 255}
 256
 257static void append_char(char **p, char c)
 258{
 259        **p = c;
 260        *p += 1;
 261}
 262
 263static void append_path_prefix(char **buffer, struct path_prefix *prefix)
 264{
 265        if (!prefix)
 266                return;
 267        append_path_prefix(buffer, prefix->prev);
 268        append_string(buffer, prefix->name);
 269        append_char(buffer, '/');
 270}
 271
 272static unsigned int path_prefix_len(struct path_prefix *prefix)
 273{
 274        if (!prefix)
 275                return 0;
 276        return path_prefix_len(prefix->prev) + strlen(prefix->name) + 1;
 277}
 278
 279static void append_path(char **p, int is_dir, const char *basepath,
 280                        struct path_prefix *prefix, const char *path)
 281{
 282        if (basepath) {
 283                append_string(p, basepath);
 284                append_char(p, '/');
 285        }
 286        append_path_prefix(p, prefix);
 287        append_string(p, path);
 288        if (is_dir)
 289                append_char(p, '/');
 290}
 291
 292static unsigned int path_len(int is_dir, const char *basepath,
 293                             struct path_prefix *prefix, const char *path)
 294{
 295        unsigned int len = 0;
 296        if (basepath)
 297                len += strlen(basepath) + 1;
 298        len += path_prefix_len(prefix) + strlen(path);
 299        if (is_dir)
 300                len++;
 301        return len;
 302}
 303
 304static void append_extended_header_prefix(char **p, unsigned int size,
 305                                          const char *keyword)
 306{
 307        int len = sprintf(*p, "%u %s=", size, keyword);
 308        *p += len;
 309}
 310
 311static unsigned int extended_header_len(const char *keyword,
 312                                        unsigned int valuelen)
 313{
 314        /* "%u %s=%s\n" */
 315        unsigned int len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 316        if (len > 9)
 317                len++;
 318        if (len > 99)
 319                len++;
 320        return len;
 321}
 322
 323static void append_extended_header(char **p, const char *keyword,
 324                                   const char *value, unsigned int len)
 325{
 326        unsigned int size = extended_header_len(keyword, len);
 327        append_extended_header_prefix(p, size, keyword);
 328        memcpy(*p, value, len);
 329        *p += len;
 330        append_char(p, '\n');
 331}
 332
 333static void write_header(const unsigned char *, char, const char *, struct path_prefix *,
 334                         const char *, unsigned int, void *, unsigned long);
 335
 336/* stores a pax extended header directly in the block buffer */
 337static void write_extended_header(const char *headerfilename, int is_dir,
 338                                  unsigned int flags, const char *basepath,
 339                                  struct path_prefix *prefix,
 340                                  const char *path, unsigned int namelen,
 341                                  void *content, unsigned int contentsize)
 342{
 343        char *buffer, *p;
 344        unsigned int pathlen, size, linkpathlen = 0;
 345
 346        size = pathlen = extended_header_len("path", namelen);
 347        if (flags & EXT_HEADER_LINKPATH) {
 348                linkpathlen = extended_header_len("linkpath", contentsize);
 349                size += linkpathlen;
 350        }
 351        write_header(NULL, TYPEFLAG_EXT_HEADER, NULL, NULL, headerfilename,
 352                     0100600, NULL, size);
 353
 354        buffer = p = malloc(size);
 355        if (!buffer)
 356                die("git-tar-tree: %s", strerror(errno));
 357        append_extended_header_prefix(&p, pathlen, "path");
 358        append_path(&p, is_dir, basepath, prefix, path);
 359        append_char(&p, '\n');
 360        if (flags & EXT_HEADER_LINKPATH)
 361                append_extended_header(&p, "linkpath", content, contentsize);
 362        write_blocked(buffer, size);
 363        free(buffer);
 364}
 365
 366static void write_global_extended_header(const unsigned char *sha1)
 367{
 368        struct strbuf ext_header;
 369        ext_header.buf = NULL;
 370        ext_header.len = ext_header.alloc = 0;
 371        strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 372        write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
 373        free(ext_header.buf);
 374}
 375
 376/* stores a ustar header directly in the block buffer */
 377static void write_header(const unsigned char *sha1, char typeflag, const char *basepath,
 378                         struct path_prefix *prefix, const char *path,
 379                         unsigned int mode, void *buffer, unsigned long size)
 380{
 381        unsigned int namelen; 
 382        char *header = NULL;
 383        unsigned int checksum = 0;
 384        int i;
 385        unsigned int ext_header = 0;
 386
 387        if (typeflag == TYPEFLAG_AUTO) {
 388                if (S_ISDIR(mode))
 389                        typeflag = TYPEFLAG_DIR;
 390                else if (S_ISLNK(mode))
 391                        typeflag = TYPEFLAG_LNK;
 392                else
 393                        typeflag = TYPEFLAG_REG;
 394        }
 395
 396        namelen = path_len(S_ISDIR(mode), basepath, prefix, path);
 397        if (namelen > 100)
 398                ext_header |= EXT_HEADER_PATH;
 399        if (typeflag == TYPEFLAG_LNK && size > 100)
 400                ext_header |= EXT_HEADER_LINKPATH;
 401
 402        /* the extended header must be written before the normal one */
 403        if (ext_header) {
 404                char headerfilename[51];
 405                sprintf(headerfilename, "%s.paxheader", sha1_to_hex(sha1));
 406                write_extended_header(headerfilename, S_ISDIR(mode),
 407                                      ext_header, basepath, prefix, path,
 408                                      namelen, buffer, size);
 409        }
 410
 411        header = get_record();
 412
 413        if (ext_header) {
 414                sprintf(header, "%s.data", sha1_to_hex(sha1));
 415        } else {
 416                char *p = header;
 417                append_path(&p, S_ISDIR(mode), basepath, prefix, path);
 418        }
 419
 420        if (typeflag == TYPEFLAG_LNK) {
 421                if (ext_header & EXT_HEADER_LINKPATH) {
 422                        sprintf(&header[157], "see %s.paxheader",
 423                                sha1_to_hex(sha1));
 424                } else {
 425                        if (buffer)
 426                                strncpy(&header[157], buffer, size);
 427                }
 428        }
 429
 430        if (S_ISDIR(mode))
 431                mode |= 0777;
 432        else if (S_ISREG(mode))
 433                mode |= (mode & 0100) ? 0777 : 0666;
 434        else if (S_ISLNK(mode))
 435                mode |= 0777;
 436        sprintf(&header[100], "%07o", mode & 07777);
 437
 438        /* XXX: should we provide more meaningful info here? */
 439        sprintf(&header[108], "%07o", 0);       /* uid */
 440        sprintf(&header[116], "%07o", 0);       /* gid */
 441        strncpy(&header[265], "git", 31);       /* uname */
 442        strncpy(&header[297], "git", 31);       /* gname */
 443
 444        if (S_ISDIR(mode) || S_ISLNK(mode))
 445                size = 0;
 446        sprintf(&header[124], "%011lo", size);
 447        sprintf(&header[136], "%011lo", archive_time);
 448
 449        header[156] = typeflag;
 450
 451        memcpy(&header[257], "ustar", 6);
 452        memcpy(&header[263], "00", 2);
 453
 454        sprintf(&header[329], "%07o", 0);       /* devmajor */
 455        sprintf(&header[337], "%07o", 0);       /* devminor */
 456
 457        memset(&header[148], ' ', 8);
 458        for (i = 0; i < RECORDSIZE; i++)
 459                checksum += header[i];
 460        sprintf(&header[148], "%07o", checksum & 0x1fffff);
 461
 462        write_if_needed();
 463}
 464
 465static void traverse_tree(struct tree_desc *tree, struct strbuf *path)
 466{
 467        int pathlen = path->len;
 468
 469        while (tree->size) {
 470                const char *name;
 471                const unsigned char *sha1;
 472                unsigned mode;
 473                void *eltbuf;
 474                char elttype[20];
 475                unsigned long eltsize;
 476
 477                sha1 = tree_entry_extract(tree, &name, &mode);
 478                update_tree_entry(tree);
 479
 480                eltbuf = read_sha1_file(sha1, elttype, &eltsize);
 481                if (!eltbuf)
 482                        die("cannot read %s", sha1_to_hex(sha1));
 483
 484                path->len = pathlen;
 485                strbuf_append_string(path, name);
 486                if (S_ISDIR(mode))
 487                        strbuf_append_string(path, "/");
 488
 489                write_entry(sha1, path, mode, eltbuf, eltsize);
 490
 491                if (S_ISDIR(mode)) {
 492                        struct tree_desc subtree;
 493                        subtree.buf = eltbuf;
 494                        subtree.size = eltsize;
 495                        traverse_tree(&subtree, path);
 496                }
 497                free(eltbuf);
 498        }
 499}
 500
 501int main(int argc, char **argv)
 502{
 503        unsigned char sha1[20], tree_sha1[20];
 504        struct commit *commit;
 505        struct tree_desc tree;
 506        struct strbuf current_path;
 507
 508        current_path.buf = xmalloc(PATH_MAX);
 509        current_path.alloc = PATH_MAX;
 510        current_path.len = current_path.eof = 0;
 511
 512        setup_git_directory();
 513
 514        switch (argc) {
 515        case 3:
 516                strbuf_append_string(&current_path, argv[2]);
 517                strbuf_append_string(&current_path, "/");
 518                /* FALLTHROUGH */
 519        case 2:
 520                if (get_sha1(argv[1], sha1) < 0)
 521                        usage(tar_tree_usage);
 522                break;
 523        default:
 524                usage(tar_tree_usage);
 525        }
 526
 527        commit = lookup_commit_reference_gently(sha1, 1);
 528        if (commit) {
 529                write_global_extended_header(commit->object.sha1);
 530                archive_time = commit->date;
 531        } else
 532                archive_time = time(NULL);
 533
 534        tree.buf = read_object_with_reference(sha1, "tree", &tree.size,
 535                                              tree_sha1);
 536        if (!tree.buf)
 537                die("not a reference to a tag, commit or tree object: %s",
 538                    sha1_to_hex(sha1));
 539
 540        if (current_path.len > 0)
 541                write_entry(tree_sha1, &current_path, 040777, NULL, 0);
 542        traverse_tree(&tree, &current_path);
 543        write_trailer();
 544        free(current_path.buf);
 545        return 0;
 546}