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[] = "git-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 = xwrite(1, buf, size);
  38                if (ret < 0) {
  39                        if (errno == EPIPE)
  40                                exit(0);
  41                        die("git-tar-tree: %s", strerror(errno));
  42                } else if (!ret) {
  43                        die("git-tar-tree: disk full?");
  44                }
  45                size -= ret;
  46                buf += ret;
  47        }
  48}
  49
  50/* writes out the whole block, but only if it is full */
  51static void write_if_needed(void)
  52{
  53        if (offset == BLOCKSIZE) {
  54                reliable_write(block, BLOCKSIZE);
  55                offset = 0;
  56        }
  57}
  58
  59/* acquire the next record from the buffer; user must call write_if_needed() */
  60static char *get_record(void)
  61{
  62        char *p = block + offset;
  63        memset(p, 0, RECORDSIZE);
  64        offset += RECORDSIZE;
  65        return p;
  66}
  67
  68/*
  69 * The end of tar archives is marked by 1024 nul bytes and after that
  70 * follows the rest of the block (if any).
  71 */
  72static void write_trailer(void)
  73{
  74        get_record();
  75        write_if_needed();
  76        get_record();
  77        write_if_needed();
  78        while (offset) {
  79                get_record();
  80                write_if_needed();
  81        }
  82}
  83
  84/*
  85 * queues up writes, so that all our write(2) calls write exactly one
  86 * full block; pads writes to RECORDSIZE
  87 */
  88static void write_blocked(void *buf, unsigned long size)
  89{
  90        unsigned long tail;
  91
  92        if (offset) {
  93                unsigned long chunk = BLOCKSIZE - offset;
  94                if (size < chunk)
  95                        chunk = size;
  96                memcpy(block + offset, buf, chunk);
  97                size -= chunk;
  98                offset += chunk;
  99                buf += chunk;
 100                write_if_needed();
 101        }
 102        while (size >= BLOCKSIZE) {
 103                reliable_write(buf, BLOCKSIZE);
 104                size -= BLOCKSIZE;
 105                buf += BLOCKSIZE;
 106        }
 107        if (size) {
 108                memcpy(block + offset, buf, size);
 109                buf += size;
 110                offset += size;
 111        }
 112        tail = offset % RECORDSIZE;
 113        if (tail)  {
 114                memset(block + offset, 0, RECORDSIZE - tail);
 115                offset += RECORDSIZE - tail;
 116        }
 117        write_if_needed();
 118}
 119
 120static void append_string(char **p, const char *s)
 121{
 122        unsigned int len = strlen(s);
 123        memcpy(*p, s, len);
 124        *p += len;
 125}
 126
 127static void append_char(char **p, char c)
 128{
 129        **p = c;
 130        *p += 1;
 131}
 132
 133static void append_path_prefix(char **buffer, struct path_prefix *prefix)
 134{
 135        if (!prefix)
 136                return;
 137        append_path_prefix(buffer, prefix->prev);
 138        append_string(buffer, prefix->name);
 139        append_char(buffer, '/');
 140}
 141
 142static unsigned int path_prefix_len(struct path_prefix *prefix)
 143{
 144        if (!prefix)
 145                return 0;
 146        return path_prefix_len(prefix->prev) + strlen(prefix->name) + 1;
 147}
 148
 149static void append_path(char **p, int is_dir, const char *basepath,
 150                        struct path_prefix *prefix, const char *path)
 151{
 152        if (basepath) {
 153                append_string(p, basepath);
 154                append_char(p, '/');
 155        }
 156        append_path_prefix(p, prefix);
 157        append_string(p, path);
 158        if (is_dir)
 159                append_char(p, '/');
 160}
 161
 162static unsigned int path_len(int is_dir, const char *basepath,
 163                             struct path_prefix *prefix, const char *path)
 164{
 165        unsigned int len = 0;
 166        if (basepath)
 167                len += strlen(basepath) + 1;
 168        len += path_prefix_len(prefix) + strlen(path);
 169        if (is_dir)
 170                len++;
 171        return len;
 172}
 173
 174static void append_extended_header_prefix(char **p, unsigned int size,
 175                                          const char *keyword)
 176{
 177        int len = sprintf(*p, "%u %s=", size, keyword);
 178        *p += len;
 179}
 180
 181static unsigned int extended_header_len(const char *keyword,
 182                                        unsigned int valuelen)
 183{
 184        /* "%u %s=%s\n" */
 185        unsigned int len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 186        if (len > 9)
 187                len++;
 188        if (len > 99)
 189                len++;
 190        return len;
 191}
 192
 193static void append_extended_header(char **p, const char *keyword,
 194                                   const char *value, unsigned int len)
 195{
 196        unsigned int size = extended_header_len(keyword, len);
 197        append_extended_header_prefix(p, size, keyword);
 198        memcpy(*p, value, len);
 199        *p += len;
 200        append_char(p, '\n');
 201}
 202
 203static void write_header(const unsigned char *, char, const char *, struct path_prefix *,
 204                         const char *, unsigned int, void *, unsigned long);
 205
 206/* stores a pax extended header directly in the block buffer */
 207static void write_extended_header(const char *headerfilename, int is_dir,
 208                                  unsigned int flags, const char *basepath,
 209                                  struct path_prefix *prefix,
 210                                  const char *path, unsigned int namelen,
 211                                  void *content, unsigned int contentsize)
 212{
 213        char *buffer, *p;
 214        unsigned int pathlen, size, linkpathlen = 0;
 215
 216        size = pathlen = extended_header_len("path", namelen);
 217        if (flags & EXT_HEADER_LINKPATH) {
 218                linkpathlen = extended_header_len("linkpath", contentsize);
 219                size += linkpathlen;
 220        }
 221        write_header(NULL, TYPEFLAG_EXT_HEADER, NULL, NULL, headerfilename,
 222                     0100600, NULL, size);
 223
 224        buffer = p = malloc(size);
 225        if (!buffer)
 226                die("git-tar-tree: %s", strerror(errno));
 227        append_extended_header_prefix(&p, pathlen, "path");
 228        append_path(&p, is_dir, basepath, prefix, path);
 229        append_char(&p, '\n');
 230        if (flags & EXT_HEADER_LINKPATH)
 231                append_extended_header(&p, "linkpath", content, contentsize);
 232        write_blocked(buffer, size);
 233        free(buffer);
 234}
 235
 236static void write_global_extended_header(const unsigned char *sha1)
 237{
 238        char *p;
 239        unsigned int size;
 240
 241        size = extended_header_len("comment", 40);
 242        write_header(NULL, TYPEFLAG_GLOBAL_HEADER, NULL, NULL,
 243                     "pax_global_header", 0100600, NULL, size);
 244
 245        p = get_record();
 246        append_extended_header(&p, "comment", sha1_to_hex(sha1), 40);
 247        write_if_needed();
 248}
 249
 250/* stores a ustar header directly in the block buffer */
 251static void write_header(const unsigned char *sha1, char typeflag, const char *basepath,
 252                         struct path_prefix *prefix, const char *path,
 253                         unsigned int mode, void *buffer, unsigned long size)
 254{
 255        unsigned int namelen; 
 256        char *header = NULL;
 257        unsigned int checksum = 0;
 258        int i;
 259        unsigned int ext_header = 0;
 260
 261        if (typeflag == TYPEFLAG_AUTO) {
 262                if (S_ISDIR(mode))
 263                        typeflag = TYPEFLAG_DIR;
 264                else if (S_ISLNK(mode))
 265                        typeflag = TYPEFLAG_LNK;
 266                else
 267                        typeflag = TYPEFLAG_REG;
 268        }
 269
 270        namelen = path_len(S_ISDIR(mode), basepath, prefix, path);
 271        if (namelen > 100)
 272                ext_header |= EXT_HEADER_PATH;
 273        if (typeflag == TYPEFLAG_LNK && size > 100)
 274                ext_header |= EXT_HEADER_LINKPATH;
 275
 276        /* the extended header must be written before the normal one */
 277        if (ext_header) {
 278                char headerfilename[51];
 279                sprintf(headerfilename, "%s.paxheader", sha1_to_hex(sha1));
 280                write_extended_header(headerfilename, S_ISDIR(mode),
 281                                      ext_header, basepath, prefix, path,
 282                                      namelen, buffer, size);
 283        }
 284
 285        header = get_record();
 286
 287        if (ext_header) {
 288                sprintf(header, "%s.data", sha1_to_hex(sha1));
 289        } else {
 290                char *p = header;
 291                append_path(&p, S_ISDIR(mode), basepath, prefix, path);
 292        }
 293
 294        if (typeflag == TYPEFLAG_LNK) {
 295                if (ext_header & EXT_HEADER_LINKPATH) {
 296                        sprintf(&header[157], "see %s.paxheader",
 297                                sha1_to_hex(sha1));
 298                } else {
 299                        if (buffer)
 300                                strncpy(&header[157], buffer, size);
 301                }
 302        }
 303
 304        if (S_ISDIR(mode))
 305                mode |= 0755;   /* GIT doesn't store permissions of dirs */
 306        if (S_ISLNK(mode))
 307                mode |= 0777;   /* ... nor of symlinks */
 308        sprintf(&header[100], "%07o", mode & 07777);
 309
 310        /* XXX: should we provide more meaningful info here? */
 311        sprintf(&header[108], "%07o", 0);       /* uid */
 312        sprintf(&header[116], "%07o", 0);       /* gid */
 313        strncpy(&header[265], "git", 31);       /* uname */
 314        strncpy(&header[297], "git", 31);       /* gname */
 315
 316        if (S_ISDIR(mode) || S_ISLNK(mode))
 317                size = 0;
 318        sprintf(&header[124], "%011lo", size);
 319        sprintf(&header[136], "%011lo", archive_time);
 320
 321        header[156] = typeflag;
 322
 323        memcpy(&header[257], "ustar", 6);
 324        memcpy(&header[263], "00", 2);
 325
 326        sprintf(&header[329], "%07o", 0);       /* devmajor */
 327        sprintf(&header[337], "%07o", 0);       /* devminor */
 328
 329        memset(&header[148], ' ', 8);
 330        for (i = 0; i < RECORDSIZE; i++)
 331                checksum += header[i];
 332        sprintf(&header[148], "%07o", checksum & 0x1fffff);
 333
 334        write_if_needed();
 335}
 336
 337static void traverse_tree(void *buffer, unsigned long size,
 338                          struct path_prefix *prefix)
 339{
 340        struct path_prefix this_prefix;
 341        this_prefix.prev = prefix;
 342
 343        while (size) {
 344                int namelen = strlen(buffer)+1;
 345                void *eltbuf;
 346                char elttype[20];
 347                unsigned long eltsize;
 348                unsigned char *sha1 = buffer + namelen;
 349                char *path = strchr(buffer, ' ') + 1;
 350                unsigned int mode;
 351
 352                if (size < namelen + 20 || sscanf(buffer, "%o", &mode) != 1)
 353                        die("corrupt 'tree' file");
 354                if (S_ISDIR(mode) || S_ISREG(mode))
 355                        mode |= (mode & 0100) ? 0777 : 0666;
 356                buffer = sha1 + 20;
 357                size -= namelen + 20;
 358
 359                eltbuf = read_sha1_file(sha1, elttype, &eltsize);
 360                if (!eltbuf)
 361                        die("cannot read %s", sha1_to_hex(sha1));
 362                write_header(sha1, TYPEFLAG_AUTO, basedir, prefix, path,
 363                             mode, eltbuf, eltsize);
 364                if (!strcmp(elttype, "tree")) {
 365                        this_prefix.name = path;
 366                        traverse_tree(eltbuf, eltsize, &this_prefix);
 367                } else if (!strcmp(elttype, "blob") && !S_ISLNK(mode)) {
 368                        write_blocked(eltbuf, eltsize);
 369                }
 370                free(eltbuf);
 371        }
 372}
 373
 374/* get commit time from committer line of commit object */
 375static time_t commit_time(void * buffer, unsigned long size)
 376{
 377        time_t result = 0;
 378        char *p = buffer;
 379
 380        while (size > 0) {
 381                char *endp = memchr(p, '\n', size);
 382                if (!endp || endp == p)
 383                        break;
 384                *endp = '\0';
 385                if (endp - p > 10 && !memcmp(p, "committer ", 10)) {
 386                        char *nump = strrchr(p, '>');
 387                        if (!nump)
 388                                break;
 389                        nump++;
 390                        result = strtoul(nump, &endp, 10);
 391                        if (*endp != ' ')
 392                                result = 0;
 393                        break;
 394                }
 395                size -= endp - p - 1;
 396                p = endp + 1;
 397        }
 398        return result;
 399}
 400
 401int main(int argc, char **argv)
 402{
 403        unsigned char sha1[20];
 404        unsigned char commit_sha1[20];
 405        void *buffer;
 406        unsigned long size;
 407
 408        setup_git_directory();
 409
 410        switch (argc) {
 411        case 3:
 412                basedir = argv[2];
 413                /* FALLTHROUGH */
 414        case 2:
 415                if (get_sha1(argv[1], sha1) < 0)
 416                        usage(tar_tree_usage);
 417                break;
 418        default:
 419                usage(tar_tree_usage);
 420        }
 421
 422        buffer = read_object_with_reference(sha1, "commit", &size, commit_sha1);
 423        if (buffer) {
 424                write_global_extended_header(commit_sha1);
 425                archive_time = commit_time(buffer, size);
 426                free(buffer);
 427        }
 428        buffer = read_object_with_reference(sha1, "tree", &size, NULL);
 429        if (!buffer)
 430                die("not a reference to a tag, commit or tree object: %s",
 431                    sha1_to_hex(sha1));
 432        if (!archive_time)
 433                archive_time = time(NULL);
 434        if (basedir)
 435                write_header((unsigned char *)"0", TYPEFLAG_DIR, NULL, NULL,
 436                        basedir, 040777, NULL, 0);
 437        traverse_tree(buffer, size, NULL);
 438        free(buffer);
 439        write_trailer();
 440        return 0;
 441}