Andrew's git - gitweb.git/blob

   1/*
   2 * Copyright (c) 2005, 2006 Rene Scharfe
   3 */
   4#include "cache.h"
   5#include "config.h"
   6#include "tar.h"
   7#include "archive.h"
   8#include "streaming.h"
   9#include "run-command.h"
  10
  11#define RECORDSIZE      (512)
  12#define BLOCKSIZE       (RECORDSIZE * 20)
  13
  14static char block[BLOCKSIZE];
  15static unsigned long offset;
  16
  17static int tar_umask = 002;
  18
  19static int write_tar_filter_archive(const struct archiver *ar,
  20                                    struct archiver_args *args);
  21
  22/*
  23 * This is the max value that a ustar size header can specify, as it is fixed
  24 * at 11 octal digits. POSIX specifies that we switch to extended headers at
  25 * this size.
  26 *
  27 * Likewise for the mtime (which happens to use a buffer of the same size).
  28 */
  29#if ULONG_MAX == 0xFFFFFFFF
  30#define USTAR_MAX_SIZE ULONG_MAX
  31#else
  32#define USTAR_MAX_SIZE 077777777777UL
  33#endif
  34#if TIME_MAX == 0xFFFFFFFF
  35#define USTAR_MAX_MTIME TIME_MAX
  36#else
  37#define USTAR_MAX_MTIME 077777777777ULL
  38#endif
  39
  40/* writes out the whole block, but only if it is full */
  41static void write_if_needed(void)
  42{
  43        if (offset == BLOCKSIZE) {
  44                write_or_die(1, block, BLOCKSIZE);
  45                offset = 0;
  46        }
  47}
  48
  49/*
  50 * queues up writes, so that all our write(2) calls write exactly one
  51 * full block; pads writes to RECORDSIZE
  52 */
  53static void do_write_blocked(const void *data, unsigned long size)
  54{
  55        const char *buf = data;
  56
  57        if (offset) {
  58                unsigned long chunk = BLOCKSIZE - offset;
  59                if (size < chunk)
  60                        chunk = size;
  61                memcpy(block + offset, buf, chunk);
  62                size -= chunk;
  63                offset += chunk;
  64                buf += chunk;
  65                write_if_needed();
  66        }
  67        while (size >= BLOCKSIZE) {
  68                write_or_die(1, buf, BLOCKSIZE);
  69                size -= BLOCKSIZE;
  70                buf += BLOCKSIZE;
  71        }
  72        if (size) {
  73                memcpy(block + offset, buf, size);
  74                offset += size;
  75        }
  76}
  77
  78static void finish_record(void)
  79{
  80        unsigned long tail;
  81        tail = offset % RECORDSIZE;
  82        if (tail)  {
  83                memset(block + offset, 0, RECORDSIZE - tail);
  84                offset += RECORDSIZE - tail;
  85        }
  86        write_if_needed();
  87}
  88
  89static void write_blocked(const void *data, unsigned long size)
  90{
  91        do_write_blocked(data, size);
  92        finish_record();
  93}
  94
  95/*
  96 * The end of tar archives is marked by 2*512 nul bytes and after that
  97 * follows the rest of the block (if any).
  98 */
  99static void write_trailer(void)
 100{
 101        int tail = BLOCKSIZE - offset;
 102        memset(block + offset, 0, tail);
 103        write_or_die(1, block, BLOCKSIZE);
 104        if (tail < 2 * RECORDSIZE) {
 105                memset(block, 0, offset);
 106                write_or_die(1, block, BLOCKSIZE);
 107        }
 108}
 109
 110/*
 111 * queues up writes, so that all our write(2) calls write exactly one
 112 * full block; pads writes to RECORDSIZE
 113 */
 114static int stream_blocked(const unsigned char *sha1)
 115{
 116        struct git_istream *st;
 117        enum object_type type;
 118        unsigned long sz;
 119        char buf[BLOCKSIZE];
 120        ssize_t readlen;
 121
 122        st = open_istream(sha1, &type, &sz, NULL);
 123        if (!st)
 124                return error("cannot stream blob %s", sha1_to_hex(sha1));
 125        for (;;) {
 126                readlen = read_istream(st, buf, sizeof(buf));
 127                if (readlen <= 0)
 128                        break;
 129                do_write_blocked(buf, readlen);
 130        }
 131        close_istream(st);
 132        if (!readlen)
 133                finish_record();
 134        return readlen;
 135}
 136
 137/*
 138 * pax extended header records have the format "%u %s=%s\n".  %u contains
 139 * the size of the whole string (including the %u), the first %s is the
 140 * keyword, the second one is the value.  This function constructs such a
 141 * string and appends it to a struct strbuf.
 142 */
 143static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 144                                     const char *value, unsigned int valuelen)
 145{
 146        int len, tmp;
 147
 148        /* "%u %s=%s\n" */
 149        len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 150        for (tmp = len; tmp > 9; tmp /= 10)
 151                len++;
 152
 153        strbuf_grow(sb, len);
 154        strbuf_addf(sb, "%u %s=", len, keyword);
 155        strbuf_add(sb, value, valuelen);
 156        strbuf_addch(sb, '\n');
 157}
 158
 159/*
 160 * Like strbuf_append_ext_header, but for numeric values.
 161 */
 162static void strbuf_append_ext_header_uint(struct strbuf *sb,
 163                                          const char *keyword,
 164                                          uintmax_t value)
 165{
 166        char buf[40]; /* big enough for 2^128 in decimal, plus NUL */
 167        int len;
 168
 169        len = xsnprintf(buf, sizeof(buf), "%"PRIuMAX, value);
 170        strbuf_append_ext_header(sb, keyword, buf, len);
 171}
 172
 173static unsigned int ustar_header_chksum(const struct ustar_header *header)
 174{
 175        const unsigned char *p = (const unsigned char *)header;
 176        unsigned int chksum = 0;
 177        while (p < (const unsigned char *)header->chksum)
 178                chksum += *p++;
 179        chksum += sizeof(header->chksum) * ' ';
 180        p += sizeof(header->chksum);
 181        while (p < (const unsigned char *)header + sizeof(struct ustar_header))
 182                chksum += *p++;
 183        return chksum;
 184}
 185
 186static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
 187{
 188        size_t i = pathlen;
 189        if (i > 1 && path[i - 1] == '/')
 190                i--;
 191        if (i > maxlen)
 192                i = maxlen;
 193        do {
 194                i--;
 195        } while (i > 0 && path[i] != '/');
 196        return i;
 197}
 198
 199static void prepare_header(struct archiver_args *args,
 200                           struct ustar_header *header,
 201                           unsigned int mode, unsigned long size)
 202{
 203        xsnprintf(header->mode, sizeof(header->mode), "%07o", mode & 07777);
 204        xsnprintf(header->size, sizeof(header->size), "%011lo", S_ISREG(mode) ? size : 0);
 205        xsnprintf(header->mtime, sizeof(header->mtime), "%011lo", (unsigned long) args->time);
 206
 207        xsnprintf(header->uid, sizeof(header->uid), "%07o", 0);
 208        xsnprintf(header->gid, sizeof(header->gid), "%07o", 0);
 209        strlcpy(header->uname, "root", sizeof(header->uname));
 210        strlcpy(header->gname, "root", sizeof(header->gname));
 211        xsnprintf(header->devmajor, sizeof(header->devmajor), "%07o", 0);
 212        xsnprintf(header->devminor, sizeof(header->devminor), "%07o", 0);
 213
 214        memcpy(header->magic, "ustar", 6);
 215        memcpy(header->version, "00", 2);
 216
 217        xsnprintf(header->chksum, sizeof(header->chksum), "%07o", ustar_header_chksum(header));
 218}
 219
 220static void write_extended_header(struct archiver_args *args,
 221                                  const unsigned char *sha1,
 222                                  const void *buffer, unsigned long size)
 223{
 224        struct ustar_header header;
 225        unsigned int mode;
 226        memset(&header, 0, sizeof(header));
 227        *header.typeflag = TYPEFLAG_EXT_HEADER;
 228        mode = 0100666;
 229        xsnprintf(header.name, sizeof(header.name), "%s.paxheader", sha1_to_hex(sha1));
 230        prepare_header(args, &header, mode, size);
 231        write_blocked(&header, sizeof(header));
 232        write_blocked(buffer, size);
 233}
 234
 235static int write_tar_entry(struct archiver_args *args,
 236                           const unsigned char *sha1,
 237                           const char *path, size_t pathlen,
 238                           unsigned int mode)
 239{
 240        struct ustar_header header;
 241        struct strbuf ext_header = STRBUF_INIT;
 242        unsigned int old_mode = mode;
 243        unsigned long size, size_in_header;
 244        void *buffer;
 245        int err = 0;
 246
 247        memset(&header, 0, sizeof(header));
 248
 249        if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 250                *header.typeflag = TYPEFLAG_DIR;
 251                mode = (mode | 0777) & ~tar_umask;
 252        } else if (S_ISLNK(mode)) {
 253                *header.typeflag = TYPEFLAG_LNK;
 254                mode |= 0777;
 255        } else if (S_ISREG(mode)) {
 256                *header.typeflag = TYPEFLAG_REG;
 257                mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 258        } else {
 259                return error("unsupported file mode: 0%o (SHA1: %s)",
 260                             mode, sha1_to_hex(sha1));
 261        }
 262        if (pathlen > sizeof(header.name)) {
 263                size_t plen = get_path_prefix(path, pathlen,
 264                                              sizeof(header.prefix));
 265                size_t rest = pathlen - plen - 1;
 266                if (plen > 0 && rest <= sizeof(header.name)) {
 267                        memcpy(header.prefix, path, plen);
 268                        memcpy(header.name, path + plen + 1, rest);
 269                } else {
 270                        xsnprintf(header.name, sizeof(header.name), "%s.data",
 271                                  sha1_to_hex(sha1));
 272                        strbuf_append_ext_header(&ext_header, "path",
 273                                                 path, pathlen);
 274                }
 275        } else
 276                memcpy(header.name, path, pathlen);
 277
 278        if (S_ISREG(mode) && !args->convert &&
 279            sha1_object_info(sha1, &size) == OBJ_BLOB &&
 280            size > big_file_threshold)
 281                buffer = NULL;
 282        else if (S_ISLNK(mode) || S_ISREG(mode)) {
 283                enum object_type type;
 284                buffer = sha1_file_to_archive(args, path, sha1, old_mode, &type, &size);
 285                if (!buffer)
 286                        return error("cannot read %s", sha1_to_hex(sha1));
 287        } else {
 288                buffer = NULL;
 289                size = 0;
 290        }
 291
 292        if (S_ISLNK(mode)) {
 293                if (size > sizeof(header.linkname)) {
 294                        xsnprintf(header.linkname, sizeof(header.linkname),
 295                                  "see %s.paxheader", sha1_to_hex(sha1));
 296                        strbuf_append_ext_header(&ext_header, "linkpath",
 297                                                 buffer, size);
 298                } else
 299                        memcpy(header.linkname, buffer, size);
 300        }
 301
 302        size_in_header = size;
 303        if (S_ISREG(mode) && size > USTAR_MAX_SIZE) {
 304                size_in_header = 0;
 305                strbuf_append_ext_header_uint(&ext_header, "size", size);
 306        }
 307
 308        prepare_header(args, &header, mode, size_in_header);
 309
 310        if (ext_header.len > 0) {
 311                write_extended_header(args, sha1, ext_header.buf,
 312                                      ext_header.len);
 313        }
 314        strbuf_release(&ext_header);
 315        write_blocked(&header, sizeof(header));
 316        if (S_ISREG(mode) && size > 0) {
 317                if (buffer)
 318                        write_blocked(buffer, size);
 319                else
 320                        err = stream_blocked(sha1);
 321        }
 322        free(buffer);
 323        return err;
 324}
 325
 326static void write_global_extended_header(struct archiver_args *args)
 327{
 328        const unsigned char *sha1 = args->commit_sha1;
 329        struct strbuf ext_header = STRBUF_INIT;
 330        struct ustar_header header;
 331        unsigned int mode;
 332
 333        if (sha1)
 334                strbuf_append_ext_header(&ext_header, "comment",
 335                                         sha1_to_hex(sha1), 40);
 336        if (args->time > USTAR_MAX_MTIME) {
 337                strbuf_append_ext_header_uint(&ext_header, "mtime",
 338                                              args->time);
 339                args->time = USTAR_MAX_MTIME;
 340        }
 341
 342        if (!ext_header.len)
 343                return;
 344
 345        memset(&header, 0, sizeof(header));
 346        *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 347        mode = 0100666;
 348        xsnprintf(header.name, sizeof(header.name), "pax_global_header");
 349        prepare_header(args, &header, mode, ext_header.len);
 350        write_blocked(&header, sizeof(header));
 351        write_blocked(ext_header.buf, ext_header.len);
 352        strbuf_release(&ext_header);
 353}
 354
 355static struct archiver **tar_filters;
 356static int nr_tar_filters;
 357static int alloc_tar_filters;
 358
 359static struct archiver *find_tar_filter(const char *name, int len)
 360{
 361        int i;
 362        for (i = 0; i < nr_tar_filters; i++) {
 363                struct archiver *ar = tar_filters[i];
 364                if (!strncmp(ar->name, name, len) && !ar->name[len])
 365                        return ar;
 366        }
 367        return NULL;
 368}
 369
 370static int tar_filter_config(const char *var, const char *value, void *data)
 371{
 372        struct archiver *ar;
 373        const char *name;
 374        const char *type;
 375        int namelen;
 376
 377        if (parse_config_key(var, "tar", &name, &namelen, &type) < 0 || !name)
 378                return 0;
 379
 380        ar = find_tar_filter(name, namelen);
 381        if (!ar) {
 382                ar = xcalloc(1, sizeof(*ar));
 383                ar->name = xmemdupz(name, namelen);
 384                ar->write_archive = write_tar_filter_archive;
 385                ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS;
 386                ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
 387                tar_filters[nr_tar_filters++] = ar;
 388        }
 389
 390        if (!strcmp(type, "command")) {
 391                if (!value)
 392                        return config_error_nonbool(var);
 393                free(ar->data);
 394                ar->data = xstrdup(value);
 395                return 0;
 396        }
 397        if (!strcmp(type, "remote")) {
 398                if (git_config_bool(var, value))
 399                        ar->flags |= ARCHIVER_REMOTE;
 400                else
 401                        ar->flags &= ~ARCHIVER_REMOTE;
 402                return 0;
 403        }
 404
 405        return 0;
 406}
 407
 408static int git_tar_config(const char *var, const char *value, void *cb)
 409{
 410        if (!strcmp(var, "tar.umask")) {
 411                if (value && !strcmp(value, "user")) {
 412                        tar_umask = umask(0);
 413                        umask(tar_umask);
 414                } else {
 415                        tar_umask = git_config_int(var, value);
 416                }
 417                return 0;
 418        }
 419
 420        return tar_filter_config(var, value, cb);
 421}
 422
 423static int write_tar_archive(const struct archiver *ar,
 424                             struct archiver_args *args)
 425{
 426        int err = 0;
 427
 428        write_global_extended_header(args);
 429        err = write_archive_entries(args, write_tar_entry);
 430        if (!err)
 431                write_trailer();
 432        return err;
 433}
 434
 435static int write_tar_filter_archive(const struct archiver *ar,
 436                                    struct archiver_args *args)
 437{
 438        struct strbuf cmd = STRBUF_INIT;
 439        struct child_process filter = CHILD_PROCESS_INIT;
 440        const char *argv[2];
 441        int r;
 442
 443        if (!ar->data)
 444                die("BUG: tar-filter archiver called with no filter defined");
 445
 446        strbuf_addstr(&cmd, ar->data);
 447        if (args->compression_level >= 0)
 448                strbuf_addf(&cmd, " -%d", args->compression_level);
 449
 450        argv[0] = cmd.buf;
 451        argv[1] = NULL;
 452        filter.argv = argv;
 453        filter.use_shell = 1;
 454        filter.in = -1;
 455
 456        if (start_command(&filter) < 0)
 457                die_errno("unable to start '%s' filter", argv[0]);
 458        close(1);
 459        if (dup2(filter.in, 1) < 0)
 460                die_errno("unable to redirect descriptor");
 461        close(filter.in);
 462
 463        r = write_tar_archive(ar, args);
 464
 465        close(1);
 466        if (finish_command(&filter) != 0)
 467                die("'%s' filter reported error", argv[0]);
 468
 469        strbuf_release(&cmd);
 470        return r;
 471}
 472
 473static struct archiver tar_archiver = {
 474        "tar",
 475        write_tar_archive,
 476        ARCHIVER_REMOTE
 477};
 478
 479void init_tar_archiver(void)
 480{
 481        int i;
 482        register_archiver(&tar_archiver);
 483
 484        tar_filter_config("tar.tgz.command", "gzip -cn", NULL);
 485        tar_filter_config("tar.tgz.remote", "true", NULL);
 486        tar_filter_config("tar.tar.gz.command", "gzip -cn", NULL);
 487        tar_filter_config("tar.tar.gz.remote", "true", NULL);
 488        git_config(git_tar_config, NULL);
 489        for (i = 0; i < nr_tar_filters; i++) {
 490                /* omit any filters that never had a command configured */
 491                if (tar_filters[i]->data)
 492                        register_archiver(tar_filters[i]);
 493        }
 494}