Andrew's git / gitweb.git / tar-tree.c
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tar-tree.con commit tar-tree: Introduce write_entry() (ae64bbc)
   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
 117/*
 118 * pax extended header records have the format "%u %s=%s\n".  %u contains
 119 * the size of the whole string (including the %u), the first %s is the
 120 * keyword, the second one is the value.  This function constructs such a
 121 * string and appends it to a struct strbuf.
 122 */
 123static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 124                                     const char *value, unsigned int valuelen)
 125{
 126        char *p;
 127        int len, total, tmp;
 128
 129        /* "%u %s=%s\n" */
 130        len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 131        for (tmp = len; tmp > 9; tmp /= 10)
 132                len++;
 133
 134        total = sb->len + len;
 135        if (total > sb->alloc) {
 136                sb->buf = xrealloc(sb->buf, total);
 137                sb->alloc = total;
 138        }
 139
 140        p = sb->buf;
 141        p += sprintf(p, "%u %s=", len, keyword);
 142        memcpy(p, value, valuelen);
 143        p += valuelen;
 144        *p = '\n';
 145        sb->len = total;
 146}
 147
 148static unsigned int ustar_header_chksum(const struct ustar_header *header)
 149{
 150        char *p = (char *)header;
 151        unsigned int chksum = 0;
 152        while (p < header->chksum)
 153                chksum += *p++;
 154        chksum += sizeof(header->chksum) * ' ';
 155        p += sizeof(header->chksum);
 156        while (p < (char *)header + sizeof(struct ustar_header))
 157                chksum += *p++;
 158        return chksum;
 159}
 160
 161static void write_entry(const unsigned char *sha1, struct strbuf *path,
 162                        unsigned int mode, void *buffer, unsigned long size)
 163{
 164        struct ustar_header header;
 165        struct strbuf ext_header;
 166
 167        memset(&header, 0, sizeof(header));
 168        ext_header.buf = NULL;
 169        ext_header.len = ext_header.alloc = 0;
 170
 171        if (!sha1) {
 172                *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 173                mode = 0100666;
 174                strcpy(header.name, "pax_global_header");
 175        } else if (!path) {
 176                *header.typeflag = TYPEFLAG_EXT_HEADER;
 177                mode = 0100666;
 178                sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 179        } else {
 180                if (S_ISDIR(mode)) {
 181                        *header.typeflag = TYPEFLAG_DIR;
 182                        mode |= 0777;
 183                } else if (S_ISLNK(mode)) {
 184                        *header.typeflag = TYPEFLAG_LNK;
 185                        mode |= 0777;
 186                } else if (S_ISREG(mode)) {
 187                        *header.typeflag = TYPEFLAG_REG;
 188                        mode |= (mode & 0100) ? 0777 : 0666;
 189                } else {
 190                        error("unsupported file mode: 0%o (SHA1: %s)",
 191                              mode, sha1_to_hex(sha1));
 192                        return;
 193                }
 194                if (path->len > sizeof(header.name)) {
 195                        sprintf(header.name, "%s.data", sha1_to_hex(sha1));
 196                        strbuf_append_ext_header(&ext_header, "path",
 197                                                 path->buf, path->len);
 198                } else
 199                        memcpy(header.name, path->buf, path->len);
 200        }
 201
 202        if (S_ISLNK(mode) && buffer) {
 203                if (size > sizeof(header.linkname)) {
 204                        sprintf(header.linkname, "see %s.paxheader",
 205                                sha1_to_hex(sha1));
 206                        strbuf_append_ext_header(&ext_header, "linkpath",
 207                                                 buffer, size);
 208                } else
 209                        memcpy(header.linkname, buffer, size);
 210        }
 211
 212        sprintf(header.mode, "%07o", mode & 07777);
 213        sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 214        sprintf(header.mtime, "%011lo", archive_time);
 215
 216        /* XXX: should we provide more meaningful info here? */
 217        sprintf(header.uid, "%07o", 0);
 218        sprintf(header.gid, "%07o", 0);
 219        strncpy(header.uname, "git", 31);
 220        strncpy(header.gname, "git", 31);
 221        sprintf(header.devmajor, "%07o", 0);
 222        sprintf(header.devminor, "%07o", 0);
 223
 224        memcpy(header.magic, "ustar", 6);
 225        memcpy(header.version, "00", 2);
 226
 227        sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 228
 229        if (ext_header.len > 0) {
 230                write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
 231                free(ext_header.buf);
 232        }
 233        write_blocked(&header, sizeof(header));
 234        if (S_ISREG(mode) && buffer && size > 0)
 235                write_blocked(buffer, size);
 236}
 237
 238static void append_string(char **p, const char *s)
 239{
 240        unsigned int len = strlen(s);
 241        memcpy(*p, s, len);
 242        *p += len;
 243}
 244
 245static void append_char(char **p, char c)
 246{
 247        **p = c;
 248        *p += 1;
 249}
 250
 251static void append_path_prefix(char **buffer, struct path_prefix *prefix)
 252{
 253        if (!prefix)
 254                return;
 255        append_path_prefix(buffer, prefix->prev);
 256        append_string(buffer, prefix->name);
 257        append_char(buffer, '/');
 258}
 259
 260static unsigned int path_prefix_len(struct path_prefix *prefix)
 261{
 262        if (!prefix)
 263                return 0;
 264        return path_prefix_len(prefix->prev) + strlen(prefix->name) + 1;
 265}
 266
 267static void append_path(char **p, int is_dir, const char *basepath,
 268                        struct path_prefix *prefix, const char *path)
 269{
 270        if (basepath) {
 271                append_string(p, basepath);
 272                append_char(p, '/');
 273        }
 274        append_path_prefix(p, prefix);
 275        append_string(p, path);
 276        if (is_dir)
 277                append_char(p, '/');
 278}
 279
 280static unsigned int path_len(int is_dir, const char *basepath,
 281                             struct path_prefix *prefix, const char *path)
 282{
 283        unsigned int len = 0;
 284        if (basepath)
 285                len += strlen(basepath) + 1;
 286        len += path_prefix_len(prefix) + strlen(path);
 287        if (is_dir)
 288                len++;
 289        return len;
 290}
 291
 292static void append_extended_header_prefix(char **p, unsigned int size,
 293                                          const char *keyword)
 294{
 295        int len = sprintf(*p, "%u %s=", size, keyword);
 296        *p += len;
 297}
 298
 299static unsigned int extended_header_len(const char *keyword,
 300                                        unsigned int valuelen)
 301{
 302        /* "%u %s=%s\n" */
 303        unsigned int len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 304        if (len > 9)
 305                len++;
 306        if (len > 99)
 307                len++;
 308        return len;
 309}
 310
 311static void append_extended_header(char **p, const char *keyword,
 312                                   const char *value, unsigned int len)
 313{
 314        unsigned int size = extended_header_len(keyword, len);
 315        append_extended_header_prefix(p, size, keyword);
 316        memcpy(*p, value, len);
 317        *p += len;
 318        append_char(p, '\n');
 319}
 320
 321static void write_header(const unsigned char *, char, const char *, struct path_prefix *,
 322                         const char *, unsigned int, void *, unsigned long);
 323
 324/* stores a pax extended header directly in the block buffer */
 325static void write_extended_header(const char *headerfilename, int is_dir,
 326                                  unsigned int flags, const char *basepath,
 327                                  struct path_prefix *prefix,
 328                                  const char *path, unsigned int namelen,
 329                                  void *content, unsigned int contentsize)
 330{
 331        char *buffer, *p;
 332        unsigned int pathlen, size, linkpathlen = 0;
 333
 334        size = pathlen = extended_header_len("path", namelen);
 335        if (flags & EXT_HEADER_LINKPATH) {
 336                linkpathlen = extended_header_len("linkpath", contentsize);
 337                size += linkpathlen;
 338        }
 339        write_header(NULL, TYPEFLAG_EXT_HEADER, NULL, NULL, headerfilename,
 340                     0100600, NULL, size);
 341
 342        buffer = p = malloc(size);
 343        if (!buffer)
 344                die("git-tar-tree: %s", strerror(errno));
 345        append_extended_header_prefix(&p, pathlen, "path");
 346        append_path(&p, is_dir, basepath, prefix, path);
 347        append_char(&p, '\n');
 348        if (flags & EXT_HEADER_LINKPATH)
 349                append_extended_header(&p, "linkpath", content, contentsize);
 350        write_blocked(buffer, size);
 351        free(buffer);
 352}
 353
 354static void write_global_extended_header(const unsigned char *sha1)
 355{
 356        struct strbuf ext_header;
 357        ext_header.buf = NULL;
 358        ext_header.len = ext_header.alloc = 0;
 359        strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 360        write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
 361        free(ext_header.buf);
 362}
 363
 364/* stores a ustar header directly in the block buffer */
 365static void write_header(const unsigned char *sha1, char typeflag, const char *basepath,
 366                         struct path_prefix *prefix, const char *path,
 367                         unsigned int mode, void *buffer, unsigned long size)
 368{
 369        unsigned int namelen; 
 370        char *header = NULL;
 371        unsigned int checksum = 0;
 372        int i;
 373        unsigned int ext_header = 0;
 374
 375        if (typeflag == TYPEFLAG_AUTO) {
 376                if (S_ISDIR(mode))
 377                        typeflag = TYPEFLAG_DIR;
 378                else if (S_ISLNK(mode))
 379                        typeflag = TYPEFLAG_LNK;
 380                else
 381                        typeflag = TYPEFLAG_REG;
 382        }
 383
 384        namelen = path_len(S_ISDIR(mode), basepath, prefix, path);
 385        if (namelen > 100)
 386                ext_header |= EXT_HEADER_PATH;
 387        if (typeflag == TYPEFLAG_LNK && size > 100)
 388                ext_header |= EXT_HEADER_LINKPATH;
 389
 390        /* the extended header must be written before the normal one */
 391        if (ext_header) {
 392                char headerfilename[51];
 393                sprintf(headerfilename, "%s.paxheader", sha1_to_hex(sha1));
 394                write_extended_header(headerfilename, S_ISDIR(mode),
 395                                      ext_header, basepath, prefix, path,
 396                                      namelen, buffer, size);
 397        }
 398
 399        header = get_record();
 400
 401        if (ext_header) {
 402                sprintf(header, "%s.data", sha1_to_hex(sha1));
 403        } else {
 404                char *p = header;
 405                append_path(&p, S_ISDIR(mode), basepath, prefix, path);
 406        }
 407
 408        if (typeflag == TYPEFLAG_LNK) {
 409                if (ext_header & EXT_HEADER_LINKPATH) {
 410                        sprintf(&header[157], "see %s.paxheader",
 411                                sha1_to_hex(sha1));
 412                } else {
 413                        if (buffer)
 414                                strncpy(&header[157], buffer, size);
 415                }
 416        }
 417
 418        if (S_ISDIR(mode))
 419                mode |= 0777;
 420        else if (S_ISREG(mode))
 421                mode |= (mode & 0100) ? 0777 : 0666;
 422        else if (S_ISLNK(mode))
 423                mode |= 0777;
 424        sprintf(&header[100], "%07o", mode & 07777);
 425
 426        /* XXX: should we provide more meaningful info here? */
 427        sprintf(&header[108], "%07o", 0);       /* uid */
 428        sprintf(&header[116], "%07o", 0);       /* gid */
 429        strncpy(&header[265], "git", 31);       /* uname */
 430        strncpy(&header[297], "git", 31);       /* gname */
 431
 432        if (S_ISDIR(mode) || S_ISLNK(mode))
 433                size = 0;
 434        sprintf(&header[124], "%011lo", size);
 435        sprintf(&header[136], "%011lo", archive_time);
 436
 437        header[156] = typeflag;
 438
 439        memcpy(&header[257], "ustar", 6);
 440        memcpy(&header[263], "00", 2);
 441
 442        sprintf(&header[329], "%07o", 0);       /* devmajor */
 443        sprintf(&header[337], "%07o", 0);       /* devminor */
 444
 445        memset(&header[148], ' ', 8);
 446        for (i = 0; i < RECORDSIZE; i++)
 447                checksum += header[i];
 448        sprintf(&header[148], "%07o", checksum & 0x1fffff);
 449
 450        write_if_needed();
 451}
 452
 453static void traverse_tree(struct tree_desc *tree,
 454                          struct path_prefix *prefix)
 455{
 456        struct path_prefix this_prefix;
 457        this_prefix.prev = prefix;
 458
 459        while (tree->size) {
 460                const char *name;
 461                const unsigned char *sha1;
 462                unsigned mode;
 463                void *eltbuf;
 464                char elttype[20];
 465                unsigned long eltsize;
 466
 467                sha1 = tree_entry_extract(tree, &name, &mode);
 468                update_tree_entry(tree);
 469
 470                eltbuf = read_sha1_file(sha1, elttype, &eltsize);
 471                if (!eltbuf)
 472                        die("cannot read %s", sha1_to_hex(sha1));
 473                write_header(sha1, TYPEFLAG_AUTO, basedir, 
 474                             prefix, name, mode, eltbuf, eltsize);
 475                if (S_ISDIR(mode)) {
 476                        struct tree_desc subtree;
 477                        subtree.buf = eltbuf;
 478                        subtree.size = eltsize;
 479                        this_prefix.name = name;
 480                        traverse_tree(&subtree, &this_prefix);
 481                } else if (!S_ISLNK(mode)) {
 482                        write_blocked(eltbuf, eltsize);
 483                }
 484                free(eltbuf);
 485        }
 486}
 487
 488int main(int argc, char **argv)
 489{
 490        unsigned char sha1[20], tree_sha1[20];
 491        struct commit *commit;
 492        struct tree_desc tree;
 493
 494        setup_git_directory();
 495
 496        switch (argc) {
 497        case 3:
 498                basedir = argv[2];
 499                /* FALLTHROUGH */
 500        case 2:
 501                if (get_sha1(argv[1], sha1) < 0)
 502                        usage(tar_tree_usage);
 503                break;
 504        default:
 505                usage(tar_tree_usage);
 506        }
 507
 508        commit = lookup_commit_reference_gently(sha1, 1);
 509        if (commit) {
 510                write_global_extended_header(commit->object.sha1);
 511                archive_time = commit->date;
 512        }
 513        tree.buf = read_object_with_reference(sha1, "tree", &tree.size,
 514                                              tree_sha1);
 515        if (!tree.buf)
 516                die("not a reference to a tag, commit or tree object: %s",
 517                    sha1_to_hex(sha1));
 518        if (!archive_time)
 519                archive_time = time(NULL);
 520        if (basedir)
 521                write_header(tree_sha1, TYPEFLAG_DIR, NULL, NULL,
 522                        basedir, 040777, NULL, 0);
 523        traverse_tree(&tree, NULL);
 524        write_trailer();
 525        return 0;
 526}