Andrew's git - gitweb.git/blob

06f4ca480e0d212b51970debdbf97a3379225330
   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/* acquire the next record from the buffer; user must call write_if_needed() */
  49static char *get_record(void)
  50{
  51        char *p = block + offset;
  52        memset(p, 0, RECORDSIZE);
  53        offset += RECORDSIZE;
  54        return p;
  55}
  56
  57/*
  58 * The end of tar archives is marked by 1024 nul bytes and after that
  59 * follows the rest of the block (if any).
  60 */
  61static void write_trailer(void)
  62{
  63        memset(block + offset, 0, RECORDSIZE);
  64        offset += RECORDSIZE;
  65        write_if_needed();
  66        memset(block + offset, 0, RECORDSIZE);
  67        offset += RECORDSIZE;
  68        write_if_needed();
  69        if (offset) {
  70                memset(block + offset, 0, BLOCKSIZE - offset);
  71                reliable_write(block, BLOCKSIZE);
  72                offset = 0;
  73        }
  74}
  75
  76/*
  77 * queues up writes, so that all our write(2) calls write exactly one
  78 * full block; pads writes to RECORDSIZE
  79 */
  80static void write_blocked(void *buf, unsigned long size)
  81{
  82        unsigned long tail;
  83
  84        if (offset) {
  85                unsigned long chunk = BLOCKSIZE - offset;
  86                if (size < chunk)
  87                        chunk = size;
  88                memcpy(block + offset, buf, chunk);
  89                size -= chunk;
  90                offset += chunk;
  91                buf += chunk;
  92                write_if_needed();
  93        }
  94        while (size >= BLOCKSIZE) {
  95                reliable_write(buf, BLOCKSIZE);
  96                size -= BLOCKSIZE;
  97                buf += BLOCKSIZE;
  98        }
  99        if (size) {
 100                memcpy(block + offset, buf, size);
 101                buf += size;
 102                offset += size;
 103        }
 104        tail = offset % RECORDSIZE;
 105        if (tail)  {
 106                memset(block + offset, 0, RECORDSIZE - tail);
 107                offset += RECORDSIZE - tail;
 108        }
 109        write_if_needed();
 110}
 111
 112static void append_string(char **p, const char *s)
 113{
 114        unsigned int len = strlen(s);
 115        memcpy(*p, s, len);
 116        *p += len;
 117}
 118
 119static void append_char(char **p, char c)
 120{
 121        **p = c;
 122        *p += 1;
 123}
 124
 125static void append_long(char **p, long n)
 126{
 127        int len = sprintf(*p, "%ld", n);
 128        *p += len;
 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 write_header(const char *, char, const char *, struct path_prefix *,
 173                         const char *, unsigned int, unsigned long);
 174
 175/* stores a pax extended header directly in the block buffer */
 176static void write_extended_header(const char *headerfilename, int is_dir,
 177                                  const char *basepath,
 178                                  struct path_prefix *prefix,
 179                                  const char *path, unsigned int namelen)
 180{
 181        char *p;
 182        unsigned int size = 1 + 6 + namelen + 1;
 183        if (size > 9)
 184                size++;
 185        if (size > 99)
 186                size++;
 187        if (size > RECORDSIZE)
 188                die("tar-tree: extended header too big, wtf?");
 189        write_header(NULL, 'x', NULL, NULL, headerfilename, 0100600, size);
 190        p = get_record();
 191        append_long(&p, size);
 192        append_string(&p, " path=");
 193        append_path(&p, is_dir, basepath, prefix, path);
 194        append_char(&p, '\n');
 195        write_if_needed();
 196}
 197
 198static void write_global_extended_header(const char *sha1)
 199{
 200        char *p;
 201        write_header(NULL, 'g', NULL, NULL, "pax_global_header", 0, 52);
 202        p = get_record();
 203        append_long(&p, 52);    /* 2 + 9 + 40 + 1 */
 204        append_string(&p, " comment=");
 205        append_string(&p, sha1_to_hex(sha1));
 206        append_char(&p, '\n');
 207        write_if_needed();
 208}
 209
 210/* stores a ustar header directly in the block buffer */
 211static void write_header(const char *sha1, char typeflag, const char *basepath,
 212                         struct path_prefix *prefix, const char *path,
 213                         unsigned int mode, unsigned long size)
 214{
 215        unsigned int namelen; 
 216        char *p, *header = NULL;
 217        unsigned int checksum = 0;
 218        int i;
 219
 220        namelen = path_len(S_ISDIR(mode), basepath, prefix, path);
 221        if (namelen > 500) {
 222                die("tar-tree: name too log of object %s\n", sha1_to_hex(sha1));
 223        } else if (namelen > 100) {
 224                char *sha1_hex = sha1_to_hex(sha1);
 225                char headerfilename[51];
 226                sprintf(headerfilename, "%s.paxheader", sha1_hex);
 227                /* the extended header must be written before the normal one */
 228                write_extended_header(headerfilename, S_ISDIR(mode), basepath,
 229                                      prefix, path, namelen);
 230
 231                header = get_record();
 232                sprintf(header, "%s.data", sha1_hex);
 233        } else {
 234                p = header = get_record();
 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(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}