Andrew's git - gitweb.git/blob

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