Andrew's git - gitweb.git/blob

277c882acc4f487bfc90dee76b00dc88f99f3da3
   1#include <time.h>
   2#include "cache.h"
   3
   4#define RECORDSIZE      (512)
   5#define BLOCKSIZE       (RECORDSIZE * 20)
   6
   7#define TYPEFLAG_AUTO           '\0'
   8#define TYPEFLAG_REG            '0'
   9#define TYPEFLAG_DIR            '5'
  10#define TYPEFLAG_GLOBAL_HEADER  'g'
  11#define TYPEFLAG_EXT_HEADER     'x'
  12
  13static const char *tar_tree_usage = "tar-tree <key> [basedir]";
  14
  15static char block[BLOCKSIZE];
  16static unsigned long offset;
  17
  18static const char *basedir;
  19static time_t archive_time;
  20
  21struct path_prefix {
  22        struct path_prefix *prev;
  23        const char *name;
  24};
  25
  26/* tries hard to write, either succeeds or dies in the attempt */
  27static void reliable_write(void *buf, unsigned long size)
  28{
  29        while (size > 0) {
  30                long ret = write(1, buf, size);
  31                if (ret < 0) {
  32                        if (errno == EAGAIN)
  33                                continue;
  34                        if (errno == EPIPE)
  35                                exit(0);
  36                        die("tar-tree: %s", strerror(errno));
  37                } else if (!ret) {
  38                        die("tar-tree: disk full?");
  39                }
  40                size -= ret;
  41                buf += ret;
  42        }
  43}
  44
  45/* writes out the whole block, but only if it is full */
  46static void write_if_needed(void)
  47{
  48        if (offset == BLOCKSIZE) {
  49                reliable_write(block, BLOCKSIZE);
  50                offset = 0;
  51        }
  52}
  53
  54/* acquire the next record from the buffer; user must call write_if_needed() */
  55static char *get_record(void)
  56{
  57        char *p = block + offset;
  58        memset(p, 0, RECORDSIZE);
  59        offset += RECORDSIZE;
  60        return p;
  61}
  62
  63/*
  64 * The end of tar archives is marked by 1024 nul bytes and after that
  65 * follows the rest of the block (if any).
  66 */
  67static void write_trailer(void)
  68{
  69        memset(block + offset, 0, RECORDSIZE);
  70        offset += RECORDSIZE;
  71        write_if_needed();
  72        memset(block + offset, 0, RECORDSIZE);
  73        offset += RECORDSIZE;
  74        write_if_needed();
  75        if (offset) {
  76                memset(block + offset, 0, BLOCKSIZE - offset);
  77                reliable_write(block, BLOCKSIZE);
  78                offset = 0;
  79        }
  80}
  81
  82/*
  83 * queues up writes, so that all our write(2) calls write exactly one
  84 * full block; pads writes to RECORDSIZE
  85 */
  86static void write_blocked(void *buf, unsigned long size)
  87{
  88        unsigned long tail;
  89
  90        if (offset) {
  91                unsigned long chunk = BLOCKSIZE - offset;
  92                if (size < chunk)
  93                        chunk = size;
  94                memcpy(block + offset, buf, chunk);
  95                size -= chunk;
  96                offset += chunk;
  97                buf += chunk;
  98                write_if_needed();
  99        }
 100        while (size >= BLOCKSIZE) {
 101                reliable_write(buf, BLOCKSIZE);
 102                size -= BLOCKSIZE;
 103                buf += BLOCKSIZE;
 104        }
 105        if (size) {
 106                memcpy(block + offset, buf, size);
 107                buf += size;
 108                offset += size;
 109        }
 110        tail = offset % RECORDSIZE;
 111        if (tail)  {
 112                memset(block + offset, 0, RECORDSIZE - tail);
 113                offset += RECORDSIZE - tail;
 114        }
 115        write_if_needed();
 116}
 117
 118static void append_string(char **p, const char *s)
 119{
 120        unsigned int len = strlen(s);
 121        memcpy(*p, s, len);
 122        *p += len;
 123}
 124
 125static void append_char(char **p, char c)
 126{
 127        **p = c;
 128        *p += 1;
 129}
 130
 131static void append_path_prefix(char **buffer, struct path_prefix *prefix)
 132{
 133        if (!prefix)
 134                return;
 135        append_path_prefix(buffer, prefix->prev);
 136        append_string(buffer, prefix->name);
 137        append_char(buffer, '/');
 138}
 139
 140static unsigned int path_prefix_len(struct path_prefix *prefix)
 141{
 142        if (!prefix)
 143                return 0;
 144        return path_prefix_len(prefix->prev) + strlen(prefix->name) + 1;
 145}
 146
 147static void append_path(char **p, int is_dir, const char *basepath,
 148                        struct path_prefix *prefix, const char *path)
 149{
 150        if (basepath) {
 151                append_string(p, basepath);
 152                append_char(p, '/');
 153        }
 154        append_path_prefix(p, prefix);
 155        append_string(p, path);
 156        if (is_dir)
 157                append_char(p, '/');
 158}
 159
 160static unsigned int path_len(int is_dir, const char *basepath,
 161                             struct path_prefix *prefix, const char *path)
 162{
 163        unsigned int len = 0;
 164        if (basepath)
 165                len += strlen(basepath) + 1;
 166        len += path_prefix_len(prefix) + strlen(path);
 167        if (is_dir)
 168                len++;
 169        return len;
 170}
 171
 172static void append_extended_header_prefix(char **p, unsigned int size,
 173                                          const char *keyword)
 174{
 175        int len = sprintf(*p, "%u %s=", size, keyword);
 176        *p += len;
 177}
 178
 179static unsigned int extended_header_len(const char *keyword,
 180                                        unsigned int valuelen)
 181{
 182        /* "%u %s=%s\n" */
 183        unsigned int len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 184        if (len > 9)
 185                len++;
 186        if (len > 99)
 187                len++;
 188        return len;
 189}
 190
 191static void append_extended_header(char **p, const char *keyword,
 192                                   const char *value, unsigned int len)
 193{
 194        unsigned int size = extended_header_len(keyword, len);
 195        append_extended_header_prefix(p, size, keyword);
 196        memcpy(*p, value, len);
 197        *p += len;
 198        append_char(p, '\n');
 199}
 200
 201static void write_header(const char *, char, const char *, struct path_prefix *,
 202                         const char *, unsigned int, unsigned long);
 203
 204/* stores a pax extended header directly in the block buffer */
 205static void write_extended_header(const char *headerfilename, int is_dir,
 206                                  const char *basepath,
 207                                  struct path_prefix *prefix,
 208                                  const char *path, unsigned int namelen)
 209{
 210        char *p;
 211        unsigned int pathlen, size;
 212
 213        size = pathlen = extended_header_len("path", namelen);
 214        if (size > RECORDSIZE)
 215                die("tar-tree: extended header too big, wtf?");
 216        write_header(NULL, TYPEFLAG_EXT_HEADER, NULL, NULL, headerfilename,
 217                     0100600, size);
 218
 219        p = get_record();
 220        append_extended_header_prefix(&p, pathlen, "path");
 221        append_path(&p, is_dir, basepath, prefix, path);
 222        append_char(&p, '\n');
 223        write_if_needed();
 224}
 225
 226static void write_global_extended_header(const char *sha1)
 227{
 228        char *p;
 229        unsigned int size;
 230
 231        size = extended_header_len("comment", 40);
 232        write_header(NULL, TYPEFLAG_GLOBAL_HEADER, NULL, NULL,
 233                     "pax_global_header", 0100600, size);
 234
 235        p = get_record();
 236        append_extended_header(&p, "comment", sha1_to_hex(sha1), 40);
 237        write_if_needed();
 238}
 239
 240/* stores a ustar header directly in the block buffer */
 241static void write_header(const char *sha1, char typeflag, const char *basepath,
 242                         struct path_prefix *prefix, const char *path,
 243                         unsigned int mode, unsigned long size)
 244{
 245        unsigned int namelen; 
 246        char *p, *header = NULL;
 247        unsigned int checksum = 0;
 248        int i;
 249
 250        if (typeflag == TYPEFLAG_AUTO) {
 251                if (S_ISDIR(mode))
 252                        typeflag = TYPEFLAG_DIR;
 253                else
 254                        typeflag = TYPEFLAG_REG;
 255        }
 256
 257        namelen = path_len(S_ISDIR(mode), basepath, prefix, path);
 258        if (namelen > 500) {
 259                die("tar-tree: name too log of object %s\n", sha1_to_hex(sha1));
 260        } else if (namelen > 100) {
 261                char *sha1_hex = sha1_to_hex(sha1);
 262                char headerfilename[51];
 263                sprintf(headerfilename, "%s.paxheader", sha1_hex);
 264                /* the extended header must be written before the normal one */
 265                write_extended_header(headerfilename, S_ISDIR(mode), basepath,
 266                                      prefix, path, namelen);
 267
 268                header = get_record();
 269                sprintf(header, "%s.data", sha1_hex);
 270        } else {
 271                p = header = get_record();
 272                append_path(&p, S_ISDIR(mode), basepath, prefix, path);
 273        }
 274
 275        if (S_ISDIR(mode))
 276                mode |= 0755;   /* GIT doesn't store permissions of dirs */
 277        sprintf(&header[100], "%07o", mode & 07777);
 278
 279        /* XXX: should we provide more meaningful info here? */
 280        sprintf(&header[108], "%07o", 0);       /* uid */
 281        sprintf(&header[116], "%07o", 0);       /* gid */
 282        strncpy(&header[265], "git", 31);       /* uname */
 283        strncpy(&header[297], "git", 31);       /* gname */
 284
 285        sprintf(&header[124], "%011lo", S_ISDIR(mode) ? 0 : size);
 286        sprintf(&header[136], "%011lo", archive_time);
 287
 288        header[156] = typeflag;
 289
 290        memcpy(&header[257], "ustar", 6);
 291        memcpy(&header[263], "00", 2);
 292
 293        printf(&header[329], "%07o", 0);        /* devmajor */
 294        printf(&header[337], "%07o", 0);        /* devminor */
 295
 296        memset(&header[148], ' ', 8);
 297        for (i = 0; i < RECORDSIZE; i++)
 298                checksum += header[i];
 299        sprintf(&header[148], "%07o", checksum & 0x1fffff);
 300
 301        write_if_needed();
 302}
 303
 304static void traverse_tree(void *buffer, unsigned long size,
 305                          struct path_prefix *prefix)
 306{
 307        struct path_prefix this_prefix;
 308        this_prefix.prev = prefix;
 309
 310        while (size) {
 311                int namelen = strlen(buffer)+1;
 312                void *eltbuf;
 313                char elttype[20];
 314                unsigned long eltsize;
 315                unsigned char *sha1 = buffer + namelen;
 316                char *path = strchr(buffer, ' ') + 1;
 317                unsigned int mode;
 318
 319                if (size < namelen + 20 || sscanf(buffer, "%o", &mode) != 1)
 320                        die("corrupt 'tree' file");
 321                buffer = sha1 + 20;
 322                size -= namelen + 20;
 323
 324                eltbuf = read_sha1_file(sha1, elttype, &eltsize);
 325                if (!eltbuf)
 326                        die("cannot read %s", sha1_to_hex(sha1));
 327                write_header(sha1, TYPEFLAG_AUTO, basedir, prefix, path,
 328                             mode, eltsize);
 329                if (!strcmp(elttype, "tree")) {
 330                        this_prefix.name = path;
 331                        traverse_tree(eltbuf, eltsize, &this_prefix);
 332                } else if (!strcmp(elttype, "blob")) {
 333                        write_blocked(eltbuf, eltsize);
 334                }
 335                free(eltbuf);
 336        }
 337}
 338
 339/* get commit time from committer line of commit object */
 340time_t commit_time(void * buffer, unsigned long size)
 341{
 342        time_t result = 0;
 343        char *p = buffer;
 344
 345        while (size > 0) {
 346                char *endp = memchr(p, '\n', size);
 347                if (!endp || endp == p)
 348                        break;
 349                *endp = '\0';
 350                if (endp - p > 10 && !memcmp(p, "committer ", 10)) {
 351                        char *nump = strrchr(p, '>');
 352                        if (!nump)
 353                                break;
 354                        nump++;
 355                        result = strtoul(nump, &endp, 10);
 356                        if (*endp != ' ')
 357                                result = 0;
 358                        break;
 359                }
 360                size -= endp - p - 1;
 361                p = endp + 1;
 362        }
 363        return result;
 364}
 365
 366int main(int argc, char **argv)
 367{
 368        unsigned char sha1[20];
 369        unsigned char commit_sha1[20];
 370        void *buffer;
 371        unsigned long size;
 372
 373        switch (argc) {
 374        case 3:
 375                basedir = argv[2];
 376                /* FALLTHROUGH */
 377        case 2:
 378                if (get_sha1(argv[1], sha1) < 0)
 379                        usage(tar_tree_usage);
 380                break;
 381        default:
 382                usage(tar_tree_usage);
 383        }
 384
 385        sha1_file_directory = getenv(DB_ENVIRONMENT);
 386        if (!sha1_file_directory)
 387                sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
 388
 389        buffer = read_object_with_reference(sha1, "commit", &size, commit_sha1);
 390        if (buffer) {
 391                write_global_extended_header(commit_sha1);
 392                archive_time = commit_time(buffer, size);
 393                free(buffer);
 394        }
 395        buffer = read_object_with_reference(sha1, "tree", &size, NULL);
 396        if (!buffer)
 397                die("not a reference to a tag, commit or tree object: %s",
 398                    sha1_to_hex(sha1));
 399        if (!archive_time)
 400                archive_time = time(NULL);
 401        if (basedir)
 402                write_header("0", TYPEFLAG_DIR, NULL, NULL, basedir, 040755, 0);
 403        traverse_tree(buffer, size, NULL);
 404        free(buffer);
 405        write_trailer();
 406        return 0;
 407}