Andrew's git / gitweb.git / archive-tar.c
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archive-tar.con commit general improvements (43abf13)
   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 "object-store.h"
   9#include "streaming.h"
  10#include "run-command.h"
  11
  12#define RECORDSIZE      (512)
  13#define BLOCKSIZE       (RECORDSIZE * 20)
  14
  15static char block[BLOCKSIZE];
  16static unsigned long offset;
  17
  18static int tar_umask = 002;
  19
  20static int write_tar_filter_archive(const struct archiver *ar,
  21                                    struct archiver_args *args);
  22
  23/*
  24 * This is the max value that a ustar size header can specify, as it is fixed
  25 * at 11 octal digits. POSIX specifies that we switch to extended headers at
  26 * this size.
  27 *
  28 * Likewise for the mtime (which happens to use a buffer of the same size).
  29 */
  30#if ULONG_MAX == 0xFFFFFFFF
  31#define USTAR_MAX_SIZE ULONG_MAX
  32#else
  33#define USTAR_MAX_SIZE 077777777777UL
  34#endif
  35#if TIME_MAX == 0xFFFFFFFF
  36#define USTAR_MAX_MTIME TIME_MAX
  37#else
  38#define USTAR_MAX_MTIME 077777777777ULL
  39#endif
  40
  41/* writes out the whole block, but only if it is full */
  42static void write_if_needed(void)
  43{
  44        if (offset == BLOCKSIZE) {
  45                write_or_die(1, block, BLOCKSIZE);
  46                offset = 0;
  47        }
  48}
  49
  50/*
  51 * queues up writes, so that all our write(2) calls write exactly one
  52 * full block; pads writes to RECORDSIZE
  53 */
  54static void do_write_blocked(const void *data, unsigned long size)
  55{
  56        const char *buf = data;
  57
  58        if (offset) {
  59                unsigned long chunk = BLOCKSIZE - offset;
  60                if (size < chunk)
  61                        chunk = size;
  62                memcpy(block + offset, buf, chunk);
  63                size -= chunk;
  64                offset += chunk;
  65                buf += chunk;
  66                write_if_needed();
  67        }
  68        while (size >= BLOCKSIZE) {
  69                write_or_die(1, buf, BLOCKSIZE);
  70                size -= BLOCKSIZE;
  71                buf += BLOCKSIZE;
  72        }
  73        if (size) {
  74                memcpy(block + offset, buf, size);
  75                offset += size;
  76        }
  77}
  78
  79static void finish_record(void)
  80{
  81        unsigned long tail;
  82        tail = offset % RECORDSIZE;
  83        if (tail)  {
  84                memset(block + offset, 0, RECORDSIZE - tail);
  85                offset += RECORDSIZE - tail;
  86        }
  87        write_if_needed();
  88}
  89
  90static void write_blocked(const void *data, unsigned long size)
  91{
  92        do_write_blocked(data, size);
  93        finish_record();
  94}
  95
  96/*
  97 * The end of tar archives is marked by 2*512 nul bytes and after that
  98 * follows the rest of the block (if any).
  99 */
 100static void write_trailer(void)
 101{
 102        int tail = BLOCKSIZE - offset;
 103        memset(block + offset, 0, tail);
 104        write_or_die(1, block, BLOCKSIZE);
 105        if (tail < 2 * RECORDSIZE) {
 106                memset(block, 0, offset);
 107                write_or_die(1, block, BLOCKSIZE);
 108        }
 109}
 110
 111/*
 112 * queues up writes, so that all our write(2) calls write exactly one
 113 * full block; pads writes to RECORDSIZE
 114 */
 115static int stream_blocked(const struct object_id *oid)
 116{
 117        struct git_istream *st;
 118        enum object_type type;
 119        unsigned long sz;
 120        char buf[BLOCKSIZE];
 121        ssize_t readlen;
 122
 123        st = open_istream(oid, &type, &sz, NULL);
 124        if (!st)
 125                return error(_("cannot stream blob %s"), oid_to_hex(oid));
 126        for (;;) {
 127                readlen = read_istream(st, buf, sizeof(buf));
 128                if (readlen <= 0)
 129                        break;
 130                do_write_blocked(buf, readlen);
 131        }
 132        close_istream(st);
 133        if (!readlen)
 134                finish_record();
 135        return readlen;
 136}
 137
 138/*
 139 * pax extended header records have the format "%u %s=%s\n".  %u contains
 140 * the size of the whole string (including the %u), the first %s is the
 141 * keyword, the second one is the value.  This function constructs such a
 142 * string and appends it to a struct strbuf.
 143 */
 144static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 145                                     const char *value, size_t valuelen)
 146{
 147        size_t orig_len = sb->len;
 148        size_t len, tmp;
 149
 150        /* "%u %s=%s\n" */
 151        len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 152        for (tmp = 1; len / 10 >= tmp; tmp *= 10)
 153                len++;
 154
 155        strbuf_grow(sb, len);
 156        strbuf_addf(sb, "%"PRIuMAX" %s=", (uintmax_t)len, keyword);
 157        strbuf_add(sb, value, valuelen);
 158        strbuf_addch(sb, '\n');
 159
 160        if (len != sb->len - orig_len)
 161                BUG("pax extended header length miscalculated as %"PRIuMAX
 162                    ", should be %"PRIuMAX,
 163                    (uintmax_t)len, (uintmax_t)(sb->len - orig_len));
 164}
 165
 166/*
 167 * Like strbuf_append_ext_header, but for numeric values.
 168 */
 169static void strbuf_append_ext_header_uint(struct strbuf *sb,
 170                                          const char *keyword,
 171                                          uintmax_t value)
 172{
 173        char buf[40]; /* big enough for 2^128 in decimal, plus NUL */
 174        int len;
 175
 176        len = xsnprintf(buf, sizeof(buf), "%"PRIuMAX, value);
 177        strbuf_append_ext_header(sb, keyword, buf, len);
 178}
 179
 180static unsigned int ustar_header_chksum(const struct ustar_header *header)
 181{
 182        const unsigned char *p = (const unsigned char *)header;
 183        unsigned int chksum = 0;
 184        while (p < (const unsigned char *)header->chksum)
 185                chksum += *p++;
 186        chksum += sizeof(header->chksum) * ' ';
 187        p += sizeof(header->chksum);
 188        while (p < (const unsigned char *)header + sizeof(struct ustar_header))
 189                chksum += *p++;
 190        return chksum;
 191}
 192
 193static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
 194{
 195        size_t i = pathlen;
 196        if (i > 1 && path[i - 1] == '/')
 197                i--;
 198        if (i > maxlen)
 199                i = maxlen;
 200        do {
 201                i--;
 202        } while (i > 0 && path[i] != '/');
 203        return i;
 204}
 205
 206static void prepare_header(struct archiver_args *args,
 207                           struct ustar_header *header,
 208                           unsigned int mode, unsigned long size)
 209{
 210        xsnprintf(header->mode, sizeof(header->mode), "%07o", mode & 07777);
 211        xsnprintf(header->size, sizeof(header->size), "%011"PRIoMAX , S_ISREG(mode) ? (uintmax_t)size : (uintmax_t)0);
 212        xsnprintf(header->mtime, sizeof(header->mtime), "%011lo", (unsigned long) args->time);
 213
 214        xsnprintf(header->uid, sizeof(header->uid), "%07o", 0);
 215        xsnprintf(header->gid, sizeof(header->gid), "%07o", 0);
 216        strlcpy(header->uname, "root", sizeof(header->uname));
 217        strlcpy(header->gname, "root", sizeof(header->gname));
 218        xsnprintf(header->devmajor, sizeof(header->devmajor), "%07o", 0);
 219        xsnprintf(header->devminor, sizeof(header->devminor), "%07o", 0);
 220
 221        memcpy(header->magic, "ustar", 6);
 222        memcpy(header->version, "00", 2);
 223
 224        xsnprintf(header->chksum, sizeof(header->chksum), "%07o", ustar_header_chksum(header));
 225}
 226
 227static void write_extended_header(struct archiver_args *args,
 228                                  const struct object_id *oid,
 229                                  const void *buffer, unsigned long size)
 230{
 231        struct ustar_header header;
 232        unsigned int mode;
 233        memset(&header, 0, sizeof(header));
 234        *header.typeflag = TYPEFLAG_EXT_HEADER;
 235        mode = 0100666;
 236        xsnprintf(header.name, sizeof(header.name), "%s.paxheader", oid_to_hex(oid));
 237        prepare_header(args, &header, mode, size);
 238        write_blocked(&header, sizeof(header));
 239        write_blocked(buffer, size);
 240}
 241
 242static int write_tar_entry(struct archiver_args *args,
 243                           const struct object_id *oid,
 244                           const char *path, size_t pathlen,
 245                           unsigned int mode)
 246{
 247        struct ustar_header header;
 248        struct strbuf ext_header = STRBUF_INIT;
 249        unsigned int old_mode = mode;
 250        unsigned long size, size_in_header;
 251        void *buffer;
 252        int err = 0;
 253
 254        memset(&header, 0, sizeof(header));
 255
 256        if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 257                *header.typeflag = TYPEFLAG_DIR;
 258                mode = (mode | 0777) & ~tar_umask;
 259        } else if (S_ISLNK(mode)) {
 260                *header.typeflag = TYPEFLAG_LNK;
 261                mode |= 0777;
 262        } else if (S_ISREG(mode)) {
 263                *header.typeflag = TYPEFLAG_REG;
 264                mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 265        } else {
 266                return error(_("unsupported file mode: 0%o (SHA1: %s)"),
 267                             mode, oid_to_hex(oid));
 268        }
 269        if (pathlen > sizeof(header.name)) {
 270                size_t plen = get_path_prefix(path, pathlen,
 271                                              sizeof(header.prefix));
 272                size_t rest = pathlen - plen - 1;
 273                if (plen > 0 && rest <= sizeof(header.name)) {
 274                        memcpy(header.prefix, path, plen);
 275                        memcpy(header.name, path + plen + 1, rest);
 276                } else {
 277                        xsnprintf(header.name, sizeof(header.name), "%s.data",
 278                                  oid_to_hex(oid));
 279                        strbuf_append_ext_header(&ext_header, "path",
 280                                                 path, pathlen);
 281                }
 282        } else
 283                memcpy(header.name, path, pathlen);
 284
 285        if (S_ISREG(mode) && !args->convert &&
 286            oid_object_info(args->repo, oid, &size) == OBJ_BLOB &&
 287            size > big_file_threshold)
 288                buffer = NULL;
 289        else if (S_ISLNK(mode) || S_ISREG(mode)) {
 290                enum object_type type;
 291                buffer = object_file_to_archive(args, path, oid, old_mode, &type, &size);
 292                if (!buffer)
 293                        return error(_("cannot read %s"), oid_to_hex(oid));
 294        } else {
 295                buffer = NULL;
 296                size = 0;
 297        }
 298
 299        if (S_ISLNK(mode)) {
 300                if (size > sizeof(header.linkname)) {
 301                        xsnprintf(header.linkname, sizeof(header.linkname),
 302                                  "see %s.paxheader", oid_to_hex(oid));
 303                        strbuf_append_ext_header(&ext_header, "linkpath",
 304                                                 buffer, size);
 305                } else
 306                        memcpy(header.linkname, buffer, size);
 307        }
 308
 309        size_in_header = size;
 310        if (S_ISREG(mode) && size > USTAR_MAX_SIZE) {
 311                size_in_header = 0;
 312                strbuf_append_ext_header_uint(&ext_header, "size", size);
 313        }
 314
 315        prepare_header(args, &header, mode, size_in_header);
 316
 317        if (ext_header.len > 0) {
 318                write_extended_header(args, oid, ext_header.buf,
 319                                      ext_header.len);
 320        }
 321        strbuf_release(&ext_header);
 322        write_blocked(&header, sizeof(header));
 323        if (S_ISREG(mode) && size > 0) {
 324                if (buffer)
 325                        write_blocked(buffer, size);
 326                else
 327                        err = stream_blocked(oid);
 328        }
 329        free(buffer);
 330        return err;
 331}
 332
 333static void write_global_extended_header(struct archiver_args *args)
 334{
 335        const struct object_id *oid = args->commit_oid;
 336        struct strbuf ext_header = STRBUF_INIT;
 337        struct ustar_header header;
 338        unsigned int mode;
 339
 340        if (oid)
 341                strbuf_append_ext_header(&ext_header, "comment",
 342                                         oid_to_hex(oid),
 343                                         the_hash_algo->hexsz);
 344        if (args->time > USTAR_MAX_MTIME) {
 345                strbuf_append_ext_header_uint(&ext_header, "mtime",
 346                                              args->time);
 347                args->time = USTAR_MAX_MTIME;
 348        }
 349
 350        if (!ext_header.len)
 351                return;
 352
 353        memset(&header, 0, sizeof(header));
 354        *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 355        mode = 0100666;
 356        xsnprintf(header.name, sizeof(header.name), "pax_global_header");
 357        prepare_header(args, &header, mode, ext_header.len);
 358        write_blocked(&header, sizeof(header));
 359        write_blocked(ext_header.buf, ext_header.len);
 360        strbuf_release(&ext_header);
 361}
 362
 363static struct archiver **tar_filters;
 364static int nr_tar_filters;
 365static int alloc_tar_filters;
 366
 367static struct archiver *find_tar_filter(const char *name, int len)
 368{
 369        int i;
 370        for (i = 0; i < nr_tar_filters; i++) {
 371                struct archiver *ar = tar_filters[i];
 372                if (!strncmp(ar->name, name, len) && !ar->name[len])
 373                        return ar;
 374        }
 375        return NULL;
 376}
 377
 378static int tar_filter_config(const char *var, const char *value, void *data)
 379{
 380        struct archiver *ar;
 381        const char *name;
 382        const char *type;
 383        int namelen;
 384
 385        if (parse_config_key(var, "tar", &name, &namelen, &type) < 0 || !name)
 386                return 0;
 387
 388        ar = find_tar_filter(name, namelen);
 389        if (!ar) {
 390                ar = xcalloc(1, sizeof(*ar));
 391                ar->name = xmemdupz(name, namelen);
 392                ar->write_archive = write_tar_filter_archive;
 393                ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS;
 394                ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
 395                tar_filters[nr_tar_filters++] = ar;
 396        }
 397
 398        if (!strcmp(type, "command")) {
 399                if (!value)
 400                        return config_error_nonbool(var);
 401                free(ar->data);
 402                ar->data = xstrdup(value);
 403                return 0;
 404        }
 405        if (!strcmp(type, "remote")) {
 406                if (git_config_bool(var, value))
 407                        ar->flags |= ARCHIVER_REMOTE;
 408                else
 409                        ar->flags &= ~ARCHIVER_REMOTE;
 410                return 0;
 411        }
 412
 413        return 0;
 414}
 415
 416static int git_tar_config(const char *var, const char *value, void *cb)
 417{
 418        if (!strcmp(var, "tar.umask")) {
 419                if (value && !strcmp(value, "user")) {
 420                        tar_umask = umask(0);
 421                        umask(tar_umask);
 422                } else {
 423                        tar_umask = git_config_int(var, value);
 424                }
 425                return 0;
 426        }
 427
 428        return tar_filter_config(var, value, cb);
 429}
 430
 431static int write_tar_archive(const struct archiver *ar,
 432                             struct archiver_args *args)
 433{
 434        int err = 0;
 435
 436        write_global_extended_header(args);
 437        err = write_archive_entries(args, write_tar_entry);
 438        if (!err)
 439                write_trailer();
 440        return err;
 441}
 442
 443static int write_tar_filter_archive(const struct archiver *ar,
 444                                    struct archiver_args *args)
 445{
 446        struct strbuf cmd = STRBUF_INIT;
 447        struct child_process filter = CHILD_PROCESS_INIT;
 448        const char *argv[2];
 449        int r;
 450
 451        if (!ar->data)
 452                BUG("tar-filter archiver called with no filter defined");
 453
 454        strbuf_addstr(&cmd, ar->data);
 455        if (args->compression_level >= 0)
 456                strbuf_addf(&cmd, " -%d", args->compression_level);
 457
 458        argv[0] = cmd.buf;
 459        argv[1] = NULL;
 460        filter.argv = argv;
 461        filter.use_shell = 1;
 462        filter.in = -1;
 463
 464        if (start_command(&filter) < 0)
 465                die_errno(_("unable to start '%s' filter"), argv[0]);
 466        close(1);
 467        if (dup2(filter.in, 1) < 0)
 468                die_errno(_("unable to redirect descriptor"));
 469        close(filter.in);
 470
 471        r = write_tar_archive(ar, args);
 472
 473        close(1);
 474        if (finish_command(&filter) != 0)
 475                die(_("'%s' filter reported error"), argv[0]);
 476
 477        strbuf_release(&cmd);
 478        return r;
 479}
 480
 481static struct archiver tar_archiver = {
 482        "tar",
 483        write_tar_archive,
 484        ARCHIVER_REMOTE
 485};
 486
 487void init_tar_archiver(void)
 488{
 489        int i;
 490        register_archiver(&tar_archiver);
 491
 492        tar_filter_config("tar.tgz.command", "gzip -cn", NULL);
 493        tar_filter_config("tar.tgz.remote", "true", NULL);
 494        tar_filter_config("tar.tar.gz.command", "gzip -cn", NULL);
 495        tar_filter_config("tar.tar.gz.remote", "true", NULL);
 496        git_config(git_tar_config, NULL);
 497        for (i = 0; i < nr_tar_filters; i++) {
 498                /* omit any filters that never had a command configured */
 499                if (tar_filters[i]->data)
 500                        register_archiver(tar_filters[i]);
 501        }
 502}