Andrew's git - gitweb.git/blob

d078cb5a8d4ab5bc2c774b889b602d179bde39b1
   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 *, 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 *records, *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, NULL, NULL, headerfilename, 0100600, size);
 181
 182        records = block + offset;
 183        memset(records, 0, RECORDSIZE);
 184        offset += RECORDSIZE;
 185        p = records;
 186        append_long(&p, size);
 187        append_string(&p, " path=");
 188        append_path(&p, is_dir, basepath, prefix, path);
 189        append_char(&p, '\n');
 190        write_if_needed();
 191}
 192
 193/* stores a ustar header directly in the block buffer */
 194static void write_header(const char *sha1, const char *basepath,
 195                         struct path_prefix *prefix, const char *path,
 196                         unsigned int mode, unsigned long size)
 197{
 198        unsigned int namelen; 
 199        char *p, *header = NULL;
 200        unsigned int checksum = 0;
 201        int i;
 202
 203        namelen = path_len(S_ISDIR(mode), basepath, prefix, path);
 204        if (namelen > 500) {
 205                die("tar-tree: name too log of object %s\n", sha1_to_hex(sha1));
 206        } else if (namelen > 100) {
 207                char *sha1_hex = sha1_to_hex(sha1);
 208                char headerfilename[51];
 209                sprintf(headerfilename, "%s.paxheader", sha1_hex);
 210                /* the extended header must be written before the normal one */
 211                write_extended_header(headerfilename, S_ISDIR(mode), basepath,
 212                                      prefix, path, namelen);
 213
 214                header = block + offset;
 215                memset(header, 0, RECORDSIZE);
 216                offset += RECORDSIZE;
 217                sprintf(header, "%s.data", sha1_hex);
 218        } else {
 219                header = block + offset;
 220                memset(header, 0, RECORDSIZE);
 221                offset += RECORDSIZE;
 222                p = header;
 223                append_path(&p, S_ISDIR(mode), basepath, prefix, path);
 224        }
 225
 226        if (S_ISDIR(mode))
 227                mode |= 0755;   /* GIT doesn't store permissions of dirs */
 228        sprintf(&header[100], "%07o", mode & 07777);
 229
 230        /* XXX: should we provide more meaningful info here? */
 231        sprintf(&header[108], "%07o", 0);       /* uid */
 232        sprintf(&header[116], "%07o", 0);       /* gid */
 233        strncpy(&header[265], "git", 31);       /* uname */
 234        strncpy(&header[297], "git", 31);       /* gname */
 235
 236        sprintf(&header[124], "%011lo", S_ISDIR(mode) ? 0 : size);
 237        sprintf(&header[136], "%011lo", archive_time);
 238
 239        /* typeflag */
 240        if (!sha1)
 241                header[156] = 'x';      /* extended header */
 242        else
 243                header[156] = S_ISDIR(mode) ? '5' : '0';
 244
 245        memcpy(&header[257], "ustar", 6);
 246        memcpy(&header[263], "00", 2);
 247
 248        printf(&header[329], "%07o", 0);        /* devmajor */
 249        printf(&header[337], "%07o", 0);        /* devminor */
 250
 251        memset(&header[148], ' ', 8);
 252        for (i = 0; i < RECORDSIZE; i++)
 253                checksum += header[i];
 254        sprintf(&header[148], "%07o", checksum & 0x1fffff);
 255
 256        write_if_needed();
 257}
 258
 259static void traverse_tree(void *buffer, unsigned long size,
 260                          struct path_prefix *prefix)
 261{
 262        struct path_prefix this_prefix;
 263        this_prefix.prev = prefix;
 264
 265        while (size) {
 266                int namelen = strlen(buffer)+1;
 267                void *eltbuf;
 268                char elttype[20];
 269                unsigned long eltsize;
 270                unsigned char *sha1 = buffer + namelen;
 271                char *path = strchr(buffer, ' ') + 1;
 272                unsigned int mode;
 273
 274                if (size < namelen + 20 || sscanf(buffer, "%o", &mode) != 1)
 275                        die("corrupt 'tree' file");
 276                buffer = sha1 + 20;
 277                size -= namelen + 20;
 278
 279                eltbuf = read_sha1_file(sha1, elttype, &eltsize);
 280                if (!eltbuf)
 281                        die("cannot read %s", sha1_to_hex(sha1));
 282                write_header(sha1, basedir, prefix, path, mode, eltsize);
 283                if (!strcmp(elttype, "tree")) {
 284                        this_prefix.name = path;
 285                        traverse_tree(eltbuf, eltsize, &this_prefix);
 286                } else if (!strcmp(elttype, "blob")) {
 287                        write_blocked(eltbuf, eltsize);
 288                }
 289                free(eltbuf);
 290        }
 291}
 292
 293/* get commit time from committer line of commit object */
 294time_t commit_time(const unsigned char *sha1)
 295{
 296        char type[20];
 297        void *buffer;
 298        unsigned long size;
 299        time_t result = 0;
 300
 301        buffer = read_sha1_file(sha1, type, &size);
 302        if (buffer) {
 303                char *p = buffer;
 304                while (size > 0) {
 305                        char *endp = memchr(p, '\n', size);
 306                        if (!endp || endp == p)
 307                                break;
 308                        *endp = '\0';
 309                        if (endp - p > 10 && !memcmp(p, "committer ", 10)) {
 310                                char *nump = strrchr(p, '>');
 311                                if (!nump)
 312                                        break;
 313                                nump++;
 314                                result = strtoul(nump, &endp, 10);
 315                                if (*endp != ' ')
 316                                        result = 0;
 317                                break;
 318                        }
 319                        size -= endp - p - 1;
 320                        p = endp + 1;
 321                }
 322                free(buffer);
 323        }
 324        return result;
 325}
 326
 327int main(int argc, char **argv)
 328{
 329        unsigned char sha1[20];
 330        void *buffer;
 331        unsigned long size;
 332        unsigned char tree_sha1[20];
 333
 334        switch (argc) {
 335        case 3:
 336                basedir = argv[2];
 337                /* FALLTHROUGH */
 338        case 2:
 339                if (get_sha1_hex(argv[1], sha1) < 0)
 340                        usage(tar_tree_usage);
 341                break;
 342        default:
 343                usage(tar_tree_usage);
 344        }
 345
 346        sha1_file_directory = getenv(DB_ENVIRONMENT);
 347        if (!sha1_file_directory)
 348                sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
 349
 350        buffer = read_tree_with_tree_or_commit_sha1(sha1, &size, tree_sha1);
 351        if (!buffer)
 352                die("unable to read sha1 file");
 353        if (memcmp(sha1, tree_sha1, 20))        /* is sha1 a commit object? */
 354                archive_time = commit_time(sha1);
 355        if (!archive_time)
 356                archive_time = time(NULL);
 357        if (basedir)
 358                write_header("0", NULL, NULL, basedir, 040755, 0);
 359        traverse_tree(buffer, size, NULL);
 360        free(buffer);
 361        write_trailer();
 362        return 0;
 363}