Andrew's git - gitweb.git/blob

   1#include <time.h>
   2#include "cache.h"
   3
   4#define RECORDSIZE      (512)
   5#define BLOCKSIZE       (RECORDSIZE * 20)
   6
   7static const char *tar_tree_usage = "tar-tree <key> [basedir]";
   8
   9static char block[BLOCKSIZE];
  10static unsigned long offset;
  11
  12static const char *basedir;
  13static time_t archive_time;
  14
  15struct path_prefix {
  16        struct path_prefix *prev;
  17        const char *name;
  18};
  19
  20/* tries hard to write, either succeeds or dies in the attempt */
  21static void reliable_write(void *buf, unsigned long size)
  22{
  23        while (size > 0) {
  24                long ret = write(1, buf, size);
  25                if (ret < 0) {
  26                        if (errno == EAGAIN)
  27                                continue;
  28                        if (errno == EPIPE)
  29                                exit(0);
  30                        die("tar-tree: %s", strerror(errno));
  31                } else if (!ret) {
  32                        die("tar-tree: disk full?");
  33                }
  34                size -= ret;
  35                buf += ret;
  36        }
  37}
  38
  39/* writes out the whole block, but only if it is full */
  40static void write_if_needed(void)
  41{
  42        if (offset == BLOCKSIZE) {
  43                reliable_write(block, BLOCKSIZE);
  44                offset = 0;
  45        }
  46}
  47
  48/*
  49 * The end of tar archives is marked by 1024 nul bytes and after that
  50 * follows the rest of the block (if any).
  51 */
  52static void write_trailer(void)
  53{
  54        memset(block + offset, 0, RECORDSIZE);
  55        offset += RECORDSIZE;
  56        write_if_needed();
  57        memset(block + offset, 0, RECORDSIZE);
  58        offset += RECORDSIZE;
  59        write_if_needed();
  60        if (offset) {
  61                memset(block + offset, 0, BLOCKSIZE - offset);
  62                reliable_write(block, BLOCKSIZE);
  63                offset = 0;
  64        }
  65}
  66
  67/*
  68 * queues up writes, so that all our write(2) calls write exactly one
  69 * full block; pads writes to RECORDSIZE
  70 */
  71static void write_blocked(void *buf, unsigned long size)
  72{
  73        unsigned long tail;
  74
  75        if (offset) {
  76                unsigned long chunk = BLOCKSIZE - offset;
  77                if (size < chunk)
  78                        chunk = size;
  79                memcpy(block + offset, buf, chunk);
  80                size -= chunk;
  81                offset += chunk;
  82                buf += chunk;
  83                write_if_needed();
  84        }
  85        while (size >= BLOCKSIZE) {
  86                reliable_write(buf, BLOCKSIZE);
  87                size -= BLOCKSIZE;
  88                buf += BLOCKSIZE;
  89        }
  90        if (size) {
  91                memcpy(block + offset, buf, size);
  92                buf += size;
  93                offset += size;
  94        }
  95        tail = offset % RECORDSIZE;
  96        if (tail)  {
  97                memset(block + offset, 0, RECORDSIZE - tail);
  98                offset += RECORDSIZE - tail;
  99        }
 100        write_if_needed();
 101}
 102
 103static void append_string(char **p, const char *s)
 104{
 105        unsigned int len = strlen(s);
 106        memcpy(*p, s, len);
 107        *p += len;
 108}
 109
 110static void append_char(char **p, char c)
 111{
 112        **p = c;
 113        *p += 1;
 114}
 115
 116static void append_long(char **p, long n)
 117{
 118        int len = sprintf(*p, "%ld", n);
 119        *p += len;
 120}
 121
 122static void append_path_prefix(char **buffer, struct path_prefix *prefix)
 123{
 124        if (!prefix)
 125                return;
 126        append_path_prefix(buffer, prefix->prev);
 127        append_string(buffer, prefix->name);
 128        append_char(buffer, '/');
 129}
 130
 131static unsigned int path_prefix_len(struct path_prefix *prefix)
 132{
 133        if (!prefix)
 134                return 0;
 135        return path_prefix_len(prefix->prev) + strlen(prefix->name) + 1;
 136}
 137
 138static void append_path(char **p, int is_dir, const char *basepath,
 139                        struct path_prefix *prefix, const char *path)
 140{
 141        if (basepath) {
 142                append_string(p, basepath);
 143                append_char(p, '/');
 144        }
 145        append_path_prefix(p, prefix);
 146        append_string(p, path);
 147        if (is_dir)
 148                append_char(p, '/');
 149}
 150
 151static unsigned int path_len(int is_dir, const char *basepath,
 152                             struct path_prefix *prefix, const char *path)
 153{
 154        unsigned int len = 0;
 155        if (basepath)
 156                len += strlen(basepath) + 1;
 157        len += path_prefix_len(prefix) + strlen(path);
 158        if (is_dir)
 159                len++;
 160        return len;
 161}
 162
 163static void write_header(const char *, char, const char *, struct path_prefix *,
 164                         const char *, unsigned int, unsigned long);
 165
 166/* stores a pax extended header directly in the block buffer */
 167static void write_extended_header(const char *headerfilename, int is_dir,
 168                                  const char *basepath,
 169                                  struct path_prefix *prefix,
 170                                  const char *path, unsigned int namelen)
 171{
 172        char *p;
 173        unsigned int size = 1 + 6 + namelen + 1;
 174        if (size > 9)
 175                size++;
 176        if (size > 99)
 177                size++;
 178        if (size > RECORDSIZE)
 179                die("tar-tree: extended header too big, wtf?");
 180        write_header(NULL, 'x', NULL, NULL, headerfilename, 0100600, size);
 181        p = block + offset;
 182        memset(p, 0, RECORDSIZE);
 183        offset += RECORDSIZE;
 184        append_long(&p, size);
 185        append_string(&p, " path=");
 186        append_path(&p, is_dir, basepath, prefix, path);
 187        append_char(&p, '\n');
 188        write_if_needed();
 189}
 190
 191static void write_global_extended_header(const char *sha1)
 192{
 193        char *p;
 194        write_header(NULL, 'g', NULL, NULL, "pax_global_header", 0, 52);
 195        p = block + offset;
 196        memset(p, 0, RECORDSIZE);
 197        offset += RECORDSIZE;
 198        append_long(&p, 52);    /* 2 + 9 + 40 + 1 */
 199        append_string(&p, " comment=");
 200        append_string(&p, sha1_to_hex(sha1));
 201        append_char(&p, '\n');
 202        write_if_needed();
 203}
 204
 205/* stores a ustar header directly in the block buffer */
 206static void write_header(const char *sha1, char typeflag, const char *basepath,
 207                         struct path_prefix *prefix, const char *path,
 208                         unsigned int mode, unsigned long size)
 209{
 210        unsigned int namelen; 
 211        char *p, *header = NULL;
 212        unsigned int checksum = 0;
 213        int i;
 214
 215        namelen = path_len(S_ISDIR(mode), basepath, prefix, path);
 216        if (namelen > 500) {
 217                die("tar-tree: name too log of object %s\n", sha1_to_hex(sha1));
 218        } else if (namelen > 100) {
 219                char *sha1_hex = sha1_to_hex(sha1);
 220                char headerfilename[51];
 221                sprintf(headerfilename, "%s.paxheader", sha1_hex);
 222                /* the extended header must be written before the normal one */
 223                write_extended_header(headerfilename, S_ISDIR(mode), basepath,
 224                                      prefix, path, namelen);
 225
 226                header = block + offset;
 227                memset(header, 0, RECORDSIZE);
 228                offset += RECORDSIZE;
 229                sprintf(header, "%s.data", sha1_hex);
 230        } else {
 231                header = block + offset;
 232                memset(header, 0, RECORDSIZE);
 233                offset += RECORDSIZE;
 234                p = header;
 235                append_path(&p, S_ISDIR(mode), basepath, prefix, path);
 236        }
 237
 238        if (S_ISDIR(mode))
 239                mode |= 0755;   /* GIT doesn't store permissions of dirs */
 240        sprintf(&header[100], "%07o", mode & 07777);
 241
 242        /* XXX: should we provide more meaningful info here? */
 243        sprintf(&header[108], "%07o", 0);       /* uid */
 244        sprintf(&header[116], "%07o", 0);       /* gid */
 245        strncpy(&header[265], "git", 31);       /* uname */
 246        strncpy(&header[297], "git", 31);       /* gname */
 247
 248        sprintf(&header[124], "%011lo", S_ISDIR(mode) ? 0 : size);
 249        sprintf(&header[136], "%011lo", archive_time);
 250
 251        header[156] = typeflag;
 252
 253        memcpy(&header[257], "ustar", 6);
 254        memcpy(&header[263], "00", 2);
 255
 256        printf(&header[329], "%07o", 0);        /* devmajor */
 257        printf(&header[337], "%07o", 0);        /* devminor */
 258
 259        memset(&header[148], ' ', 8);
 260        for (i = 0; i < RECORDSIZE; i++)
 261                checksum += header[i];
 262        sprintf(&header[148], "%07o", checksum & 0x1fffff);
 263
 264        write_if_needed();
 265}
 266
 267static void traverse_tree(void *buffer, unsigned long size,
 268                          struct path_prefix *prefix)
 269{
 270        struct path_prefix this_prefix;
 271        this_prefix.prev = prefix;
 272
 273        while (size) {
 274                int namelen = strlen(buffer)+1;
 275                void *eltbuf;
 276                char elttype[20];
 277                unsigned long eltsize;
 278                unsigned char *sha1 = buffer + namelen;
 279                char *path = strchr(buffer, ' ') + 1;
 280                unsigned int mode;
 281
 282                if (size < namelen + 20 || sscanf(buffer, "%o", &mode) != 1)
 283                        die("corrupt 'tree' file");
 284                buffer = sha1 + 20;
 285                size -= namelen + 20;
 286
 287                eltbuf = read_sha1_file(sha1, elttype, &eltsize);
 288                if (!eltbuf)
 289                        die("cannot read %s", sha1_to_hex(sha1));
 290                write_header(sha1, S_ISDIR(mode) ? '5' : '0', basedir,
 291                             prefix, path, mode, eltsize);
 292                if (!strcmp(elttype, "tree")) {
 293                        this_prefix.name = path;
 294                        traverse_tree(eltbuf, eltsize, &this_prefix);
 295                } else if (!strcmp(elttype, "blob")) {
 296                        write_blocked(eltbuf, eltsize);
 297                }
 298                free(eltbuf);
 299        }
 300}
 301
 302/* get commit time from committer line of commit object */
 303time_t commit_time(void * buffer, unsigned long size)
 304{
 305        time_t result = 0;
 306        char *p = buffer;
 307
 308        while (size > 0) {
 309                char *endp = memchr(p, '\n', size);
 310                if (!endp || endp == p)
 311                        break;
 312                *endp = '\0';
 313                if (endp - p > 10 && !memcmp(p, "committer ", 10)) {
 314                        char *nump = strrchr(p, '>');
 315                        if (!nump)
 316                                break;
 317                        nump++;
 318                        result = strtoul(nump, &endp, 10);
 319                        if (*endp != ' ')
 320                                result = 0;
 321                        break;
 322                }
 323                size -= endp - p - 1;
 324                p = endp + 1;
 325        }
 326        return result;
 327}
 328
 329int main(int argc, char **argv)
 330{
 331        unsigned char sha1[20];
 332        unsigned char commit_sha1[20];
 333        void *buffer;
 334        unsigned long size;
 335
 336        switch (argc) {
 337        case 3:
 338                basedir = argv[2];
 339                /* FALLTHROUGH */
 340        case 2:
 341                if (get_sha1_hex(argv[1], sha1) < 0)
 342                        usage(tar_tree_usage);
 343                break;
 344        default:
 345                usage(tar_tree_usage);
 346        }
 347
 348        sha1_file_directory = getenv(DB_ENVIRONMENT);
 349        if (!sha1_file_directory)
 350                sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
 351
 352        buffer = read_object_with_reference(sha1, "commit", &size, commit_sha1);
 353        if (buffer) {
 354                write_global_extended_header(commit_sha1);
 355                archive_time = commit_time(buffer, size);
 356                free(buffer);
 357        }
 358        buffer = read_object_with_reference(sha1, "tree", &size, NULL);
 359        if (!buffer)
 360                die("not a reference to a tag, commit or tree object: %s",
 361                    sha1_to_hex(sha1));
 362        if (!archive_time)
 363                archive_time = time(NULL);
 364        if (basedir)
 365                write_header("0", '5', NULL, NULL, basedir, 040755, 0);
 366        traverse_tree(buffer, size, NULL);
 367        free(buffer);
 368        write_trailer();
 369        return 0;
 370}