Andrew's git - gitweb.git/blob

   1/*
   2 * Copyright (c) 2005 Rene Scharfe
   3 */
   4#include <time.h>
   5#include "cache.h"
   6
   7#define RECORDSIZE      (512)
   8#define BLOCKSIZE       (RECORDSIZE * 20)
   9
  10#define TYPEFLAG_AUTO           '\0'
  11#define TYPEFLAG_REG            '0'
  12#define TYPEFLAG_LNK            '2'
  13#define TYPEFLAG_DIR            '5'
  14#define TYPEFLAG_GLOBAL_HEADER  'g'
  15#define TYPEFLAG_EXT_HEADER     'x'
  16
  17#define EXT_HEADER_PATH         1
  18#define EXT_HEADER_LINKPATH     2
  19
  20static const char *tar_tree_usage = "tar-tree <key> [basedir]";
  21
  22static char block[BLOCKSIZE];
  23static unsigned long offset;
  24
  25static const char *basedir;
  26static time_t archive_time;
  27
  28struct path_prefix {
  29        struct path_prefix *prev;
  30        const char *name;
  31};
  32
  33/* tries hard to write, either succeeds or dies in the attempt */
  34static void reliable_write(void *buf, unsigned long size)
  35{
  36        while (size > 0) {
  37                long ret = write(1, buf, size);
  38                if (ret < 0) {
  39                        if (errno == EAGAIN)
  40                                continue;
  41                        if (errno == EPIPE)
  42                                exit(0);
  43                        die("tar-tree: %s", strerror(errno));
  44                } else if (!ret) {
  45                        die("tar-tree: disk full?");
  46                }
  47                size -= ret;
  48                buf += ret;
  49        }
  50}
  51
  52/* writes out the whole block, but only if it is full */
  53static void write_if_needed(void)
  54{
  55        if (offset == BLOCKSIZE) {
  56                reliable_write(block, BLOCKSIZE);
  57                offset = 0;
  58        }
  59}
  60
  61/* acquire the next record from the buffer; user must call write_if_needed() */
  62static char *get_record(void)
  63{
  64        char *p = block + offset;
  65        memset(p, 0, RECORDSIZE);
  66        offset += RECORDSIZE;
  67        return p;
  68}
  69
  70/*
  71 * The end of tar archives is marked by 1024 nul bytes and after that
  72 * follows the rest of the block (if any).
  73 */
  74static void write_trailer(void)
  75{
  76        memset(block + offset, 0, RECORDSIZE);
  77        offset += RECORDSIZE;
  78        write_if_needed();
  79        memset(block + offset, 0, RECORDSIZE);
  80        offset += RECORDSIZE;
  81        write_if_needed();
  82        if (offset) {
  83                memset(block + offset, 0, BLOCKSIZE - offset);
  84                reliable_write(block, BLOCKSIZE);
  85                offset = 0;
  86        }
  87}
  88
  89/*
  90 * queues up writes, so that all our write(2) calls write exactly one
  91 * full block; pads writes to RECORDSIZE
  92 */
  93static void write_blocked(void *buf, unsigned long size)
  94{
  95        unsigned long tail;
  96
  97        if (offset) {
  98                unsigned long chunk = BLOCKSIZE - offset;
  99                if (size < chunk)
 100                        chunk = size;
 101                memcpy(block + offset, buf, chunk);
 102                size -= chunk;
 103                offset += chunk;
 104                buf += chunk;
 105                write_if_needed();
 106        }
 107        while (size >= BLOCKSIZE) {
 108                reliable_write(buf, BLOCKSIZE);
 109                size -= BLOCKSIZE;
 110                buf += BLOCKSIZE;
 111        }
 112        if (size) {
 113                memcpy(block + offset, buf, size);
 114                buf += size;
 115                offset += size;
 116        }
 117        tail = offset % RECORDSIZE;
 118        if (tail)  {
 119                memset(block + offset, 0, RECORDSIZE - tail);
 120                offset += RECORDSIZE - tail;
 121        }
 122        write_if_needed();
 123}
 124
 125static void append_string(char **p, const char *s)
 126{
 127        unsigned int len = strlen(s);
 128        memcpy(*p, s, len);
 129        *p += len;
 130}
 131
 132static void append_char(char **p, char c)
 133{
 134        **p = c;
 135        *p += 1;
 136}
 137
 138static void append_path_prefix(char **buffer, struct path_prefix *prefix)
 139{
 140        if (!prefix)
 141                return;
 142        append_path_prefix(buffer, prefix->prev);
 143        append_string(buffer, prefix->name);
 144        append_char(buffer, '/');
 145}
 146
 147static unsigned int path_prefix_len(struct path_prefix *prefix)
 148{
 149        if (!prefix)
 150                return 0;
 151        return path_prefix_len(prefix->prev) + strlen(prefix->name) + 1;
 152}
 153
 154static void append_path(char **p, int is_dir, const char *basepath,
 155                        struct path_prefix *prefix, const char *path)
 156{
 157        if (basepath) {
 158                append_string(p, basepath);
 159                append_char(p, '/');
 160        }
 161        append_path_prefix(p, prefix);
 162        append_string(p, path);
 163        if (is_dir)
 164                append_char(p, '/');
 165}
 166
 167static unsigned int path_len(int is_dir, const char *basepath,
 168                             struct path_prefix *prefix, const char *path)
 169{
 170        unsigned int len = 0;
 171        if (basepath)
 172                len += strlen(basepath) + 1;
 173        len += path_prefix_len(prefix) + strlen(path);
 174        if (is_dir)
 175                len++;
 176        return len;
 177}
 178
 179static void append_extended_header_prefix(char **p, unsigned int size,
 180                                          const char *keyword)
 181{
 182        int len = sprintf(*p, "%u %s=", size, keyword);
 183        *p += len;
 184}
 185
 186static unsigned int extended_header_len(const char *keyword,
 187                                        unsigned int valuelen)
 188{
 189        /* "%u %s=%s\n" */
 190        unsigned int len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 191        if (len > 9)
 192                len++;
 193        if (len > 99)
 194                len++;
 195        return len;
 196}
 197
 198static void append_extended_header(char **p, const char *keyword,
 199                                   const char *value, unsigned int len)
 200{
 201        unsigned int size = extended_header_len(keyword, len);
 202        append_extended_header_prefix(p, size, keyword);
 203        memcpy(*p, value, len);
 204        *p += len;
 205        append_char(p, '\n');
 206}
 207
 208static void write_header(const char *, char, const char *, struct path_prefix *,
 209                         const char *, unsigned int, void *, unsigned long);
 210
 211/* stores a pax extended header directly in the block buffer */
 212static void write_extended_header(const char *headerfilename, int is_dir,
 213                                  unsigned int flags, const char *basepath,
 214                                  struct path_prefix *prefix,
 215                                  const char *path, unsigned int namelen,
 216                                  void *content, unsigned int contentsize)
 217{
 218        char *buffer, *p;
 219        unsigned int pathlen, size, linkpathlen = 0;
 220
 221        size = pathlen = extended_header_len("path", namelen);
 222        if (flags & EXT_HEADER_LINKPATH) {
 223                linkpathlen = extended_header_len("linkpath", contentsize);
 224                size += linkpathlen;
 225        }
 226        write_header(NULL, TYPEFLAG_EXT_HEADER, NULL, NULL, headerfilename,
 227                     0100600, NULL, size);
 228
 229        buffer = p = malloc(size);
 230        if (!buffer)
 231                die("git-tar-tree: %s", strerror(errno));
 232        append_extended_header_prefix(&p, pathlen, "path");
 233        append_path(&p, is_dir, basepath, prefix, path);
 234        append_char(&p, '\n');
 235        if (flags & EXT_HEADER_LINKPATH)
 236                append_extended_header(&p, "linkpath", content, contentsize);
 237        write_blocked(buffer, size);
 238        free(buffer);
 239}
 240
 241static void write_global_extended_header(const char *sha1)
 242{
 243        char *p;
 244        unsigned int size;
 245
 246        size = extended_header_len("comment", 40);
 247        write_header(NULL, TYPEFLAG_GLOBAL_HEADER, NULL, NULL,
 248                     "pax_global_header", 0100600, NULL, size);
 249
 250        p = get_record();
 251        append_extended_header(&p, "comment", sha1_to_hex(sha1), 40);
 252        write_if_needed();
 253}
 254
 255/* stores a ustar header directly in the block buffer */
 256static void write_header(const char *sha1, char typeflag, const char *basepath,
 257                         struct path_prefix *prefix, const char *path,
 258                         unsigned int mode, void *buffer, unsigned long size)
 259{
 260        unsigned int namelen; 
 261        char *header = NULL;
 262        unsigned int checksum = 0;
 263        int i;
 264        unsigned int ext_header = 0;
 265
 266        if (typeflag == TYPEFLAG_AUTO) {
 267                if (S_ISDIR(mode))
 268                        typeflag = TYPEFLAG_DIR;
 269                else if (S_ISLNK(mode))
 270                        typeflag = TYPEFLAG_LNK;
 271                else
 272                        typeflag = TYPEFLAG_REG;
 273        }
 274
 275        namelen = path_len(S_ISDIR(mode), basepath, prefix, path);
 276        if (namelen > 100)
 277                ext_header |= EXT_HEADER_PATH;
 278        if (typeflag == TYPEFLAG_LNK && size > 100)
 279                ext_header |= EXT_HEADER_LINKPATH;
 280
 281        /* the extended header must be written before the normal one */
 282        if (ext_header) {
 283                char headerfilename[51];
 284                sprintf(headerfilename, "%s.paxheader", sha1_to_hex(sha1));
 285                write_extended_header(headerfilename, S_ISDIR(mode),
 286                                      ext_header, basepath, prefix, path,
 287                                      namelen, buffer, size);
 288        }
 289
 290        header = get_record();
 291
 292        if (ext_header) {
 293                sprintf(header, "%s.data", sha1_to_hex(sha1));
 294        } else {
 295                char *p = header;
 296                append_path(&p, S_ISDIR(mode), basepath, prefix, path);
 297        }
 298
 299        if (typeflag == TYPEFLAG_LNK) {
 300                if (ext_header & EXT_HEADER_LINKPATH) {
 301                        sprintf(&header[157], "see %s.paxheader",
 302                                sha1_to_hex(sha1));
 303                } else {
 304                        if (buffer)
 305                                strncpy(&header[157], buffer, size);
 306                }
 307        }
 308
 309        if (S_ISDIR(mode))
 310                mode |= 0755;   /* GIT doesn't store permissions of dirs */
 311        if (S_ISLNK(mode))
 312                mode |= 0777;   /* ... nor of symlinks */
 313        sprintf(&header[100], "%07o", mode & 07777);
 314
 315        /* XXX: should we provide more meaningful info here? */
 316        sprintf(&header[108], "%07o", 0);       /* uid */
 317        sprintf(&header[116], "%07o", 0);       /* gid */
 318        strncpy(&header[265], "git", 31);       /* uname */
 319        strncpy(&header[297], "git", 31);       /* gname */
 320
 321        if (S_ISDIR(mode) || S_ISLNK(mode))
 322                size = 0;
 323        sprintf(&header[124], "%011lo", size);
 324        sprintf(&header[136], "%011lo", archive_time);
 325
 326        header[156] = typeflag;
 327
 328        memcpy(&header[257], "ustar", 6);
 329        memcpy(&header[263], "00", 2);
 330
 331        printf(&header[329], "%07o", 0);        /* devmajor */
 332        printf(&header[337], "%07o", 0);        /* devminor */
 333
 334        memset(&header[148], ' ', 8);
 335        for (i = 0; i < RECORDSIZE; i++)
 336                checksum += header[i];
 337        sprintf(&header[148], "%07o", checksum & 0x1fffff);
 338
 339        write_if_needed();
 340}
 341
 342static void traverse_tree(void *buffer, unsigned long size,
 343                          struct path_prefix *prefix)
 344{
 345        struct path_prefix this_prefix;
 346        this_prefix.prev = prefix;
 347
 348        while (size) {
 349                int namelen = strlen(buffer)+1;
 350                void *eltbuf;
 351                char elttype[20];
 352                unsigned long eltsize;
 353                unsigned char *sha1 = buffer + namelen;
 354                char *path = strchr(buffer, ' ') + 1;
 355                unsigned int mode;
 356
 357                if (size < namelen + 20 || sscanf(buffer, "%o", &mode) != 1)
 358                        die("corrupt 'tree' file");
 359                buffer = sha1 + 20;
 360                size -= namelen + 20;
 361
 362                eltbuf = read_sha1_file(sha1, elttype, &eltsize);
 363                if (!eltbuf)
 364                        die("cannot read %s", sha1_to_hex(sha1));
 365                write_header(sha1, TYPEFLAG_AUTO, basedir, prefix, path,
 366                             mode, eltbuf, eltsize);
 367                if (!strcmp(elttype, "tree")) {
 368                        this_prefix.name = path;
 369                        traverse_tree(eltbuf, eltsize, &this_prefix);
 370                } else if (!strcmp(elttype, "blob") && !S_ISLNK(mode)) {
 371                        write_blocked(eltbuf, eltsize);
 372                }
 373                free(eltbuf);
 374        }
 375}
 376
 377/* get commit time from committer line of commit object */
 378time_t commit_time(void * buffer, unsigned long size)
 379{
 380        time_t result = 0;
 381        char *p = buffer;
 382
 383        while (size > 0) {
 384                char *endp = memchr(p, '\n', size);
 385                if (!endp || endp == p)
 386                        break;
 387                *endp = '\0';
 388                if (endp - p > 10 && !memcmp(p, "committer ", 10)) {
 389                        char *nump = strrchr(p, '>');
 390                        if (!nump)
 391                                break;
 392                        nump++;
 393                        result = strtoul(nump, &endp, 10);
 394                        if (*endp != ' ')
 395                                result = 0;
 396                        break;
 397                }
 398                size -= endp - p - 1;
 399                p = endp + 1;
 400        }
 401        return result;
 402}
 403
 404int main(int argc, char **argv)
 405{
 406        unsigned char sha1[20];
 407        unsigned char commit_sha1[20];
 408        void *buffer;
 409        unsigned long size;
 410
 411        switch (argc) {
 412        case 3:
 413                basedir = argv[2];
 414                /* FALLTHROUGH */
 415        case 2:
 416                if (get_sha1(argv[1], sha1) < 0)
 417                        usage(tar_tree_usage);
 418                break;
 419        default:
 420                usage(tar_tree_usage);
 421        }
 422
 423        buffer = read_object_with_reference(sha1, "commit", &size, commit_sha1);
 424        if (buffer) {
 425                write_global_extended_header(commit_sha1);
 426                archive_time = commit_time(buffer, size);
 427                free(buffer);
 428        }
 429        buffer = read_object_with_reference(sha1, "tree", &size, NULL);
 430        if (!buffer)
 431                die("not a reference to a tag, commit or tree object: %s",
 432                    sha1_to_hex(sha1));
 433        if (!archive_time)
 434                archive_time = time(NULL);
 435        if (basedir)
 436                write_header("0", TYPEFLAG_DIR, NULL, NULL, basedir, 040755,
 437                             NULL, 0);
 438        traverse_tree(buffer, size, NULL);
 439        free(buffer);
 440        write_trailer();
 441        return 0;
 442}