Andrew's git - gitweb.git/blob

7ea4e90814d26b99c9e2de598daa874ec4b216fd
   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#define USTAR_MAX_SIZE 077777777777UL
  29#define USTAR_MAX_MTIME 077777777777UL
  30
  31/* writes out the whole block, but only if it is full */
  32static void write_if_needed(void)
  33{
  34        if (offset == BLOCKSIZE) {
  35                write_or_die(1, block, BLOCKSIZE);
  36                offset = 0;
  37        }
  38}
  39
  40/*
  41 * queues up writes, so that all our write(2) calls write exactly one
  42 * full block; pads writes to RECORDSIZE
  43 */
  44static void do_write_blocked(const void *data, unsigned long size)
  45{
  46        const char *buf = data;
  47
  48        if (offset) {
  49                unsigned long chunk = BLOCKSIZE - offset;
  50                if (size < chunk)
  51                        chunk = size;
  52                memcpy(block + offset, buf, chunk);
  53                size -= chunk;
  54                offset += chunk;
  55                buf += chunk;
  56                write_if_needed();
  57        }
  58        while (size >= BLOCKSIZE) {
  59                write_or_die(1, buf, BLOCKSIZE);
  60                size -= BLOCKSIZE;
  61                buf += BLOCKSIZE;
  62        }
  63        if (size) {
  64                memcpy(block + offset, buf, size);
  65                offset += size;
  66        }
  67}
  68
  69static void finish_record(void)
  70{
  71        unsigned long tail;
  72        tail = offset % RECORDSIZE;
  73        if (tail)  {
  74                memset(block + offset, 0, RECORDSIZE - tail);
  75                offset += RECORDSIZE - tail;
  76        }
  77        write_if_needed();
  78}
  79
  80static void write_blocked(const void *data, unsigned long size)
  81{
  82        do_write_blocked(data, size);
  83        finish_record();
  84}
  85
  86/*
  87 * The end of tar archives is marked by 2*512 nul bytes and after that
  88 * follows the rest of the block (if any).
  89 */
  90static void write_trailer(void)
  91{
  92        int tail = BLOCKSIZE - offset;
  93        memset(block + offset, 0, tail);
  94        write_or_die(1, block, BLOCKSIZE);
  95        if (tail < 2 * RECORDSIZE) {
  96                memset(block, 0, offset);
  97                write_or_die(1, block, BLOCKSIZE);
  98        }
  99}
 100
 101/*
 102 * queues up writes, so that all our write(2) calls write exactly one
 103 * full block; pads writes to RECORDSIZE
 104 */
 105static int stream_blocked(const unsigned char *sha1)
 106{
 107        struct git_istream *st;
 108        enum object_type type;
 109        unsigned long sz;
 110        char buf[BLOCKSIZE];
 111        ssize_t readlen;
 112
 113        st = open_istream(sha1, &type, &sz, NULL);
 114        if (!st)
 115                return error("cannot stream blob %s", sha1_to_hex(sha1));
 116        for (;;) {
 117                readlen = read_istream(st, buf, sizeof(buf));
 118                if (readlen <= 0)
 119                        break;
 120                do_write_blocked(buf, readlen);
 121        }
 122        close_istream(st);
 123        if (!readlen)
 124                finish_record();
 125        return readlen;
 126}
 127
 128/*
 129 * pax extended header records have the format "%u %s=%s\n".  %u contains
 130 * the size of the whole string (including the %u), the first %s is the
 131 * keyword, the second one is the value.  This function constructs such a
 132 * string and appends it to a struct strbuf.
 133 */
 134static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 135                                     const char *value, unsigned int valuelen)
 136{
 137        int len, tmp;
 138
 139        /* "%u %s=%s\n" */
 140        len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 141        for (tmp = len; tmp > 9; tmp /= 10)
 142                len++;
 143
 144        strbuf_grow(sb, len);
 145        strbuf_addf(sb, "%u %s=", len, keyword);
 146        strbuf_add(sb, value, valuelen);
 147        strbuf_addch(sb, '\n');
 148}
 149
 150/*
 151 * Like strbuf_append_ext_header, but for numeric values.
 152 */
 153static void strbuf_append_ext_header_uint(struct strbuf *sb,
 154                                          const char *keyword,
 155                                          uintmax_t value)
 156{
 157        char buf[40]; /* big enough for 2^128 in decimal, plus NUL */
 158        int len;
 159
 160        len = xsnprintf(buf, sizeof(buf), "%"PRIuMAX, value);
 161        strbuf_append_ext_header(sb, keyword, buf, len);
 162}
 163
 164static unsigned int ustar_header_chksum(const struct ustar_header *header)
 165{
 166        const unsigned char *p = (const unsigned char *)header;
 167        unsigned int chksum = 0;
 168        while (p < (const unsigned char *)header->chksum)
 169                chksum += *p++;
 170        chksum += sizeof(header->chksum) * ' ';
 171        p += sizeof(header->chksum);
 172        while (p < (const unsigned char *)header + sizeof(struct ustar_header))
 173                chksum += *p++;
 174        return chksum;
 175}
 176
 177static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
 178{
 179        size_t i = pathlen;
 180        if (i > 1 && path[i - 1] == '/')
 181                i--;
 182        if (i > maxlen)
 183                i = maxlen;
 184        do {
 185                i--;
 186        } while (i > 0 && path[i] != '/');
 187        return i;
 188}
 189
 190static void prepare_header(struct archiver_args *args,
 191                           struct ustar_header *header,
 192                           unsigned int mode, unsigned long size)
 193{
 194        xsnprintf(header->mode, sizeof(header->mode), "%07o", mode & 07777);
 195        xsnprintf(header->size, sizeof(header->size), "%011lo", S_ISREG(mode) ? size : 0);
 196        xsnprintf(header->mtime, sizeof(header->mtime), "%011lo", (unsigned long) args->time);
 197
 198        xsnprintf(header->uid, sizeof(header->uid), "%07o", 0);
 199        xsnprintf(header->gid, sizeof(header->gid), "%07o", 0);
 200        strlcpy(header->uname, "root", sizeof(header->uname));
 201        strlcpy(header->gname, "root", sizeof(header->gname));
 202        xsnprintf(header->devmajor, sizeof(header->devmajor), "%07o", 0);
 203        xsnprintf(header->devminor, sizeof(header->devminor), "%07o", 0);
 204
 205        memcpy(header->magic, "ustar", 6);
 206        memcpy(header->version, "00", 2);
 207
 208        xsnprintf(header->chksum, sizeof(header->chksum), "%07o", ustar_header_chksum(header));
 209}
 210
 211static int write_extended_header(struct archiver_args *args,
 212                                 const unsigned char *sha1,
 213                                 const void *buffer, unsigned long size)
 214{
 215        struct ustar_header header;
 216        unsigned int mode;
 217        memset(&header, 0, sizeof(header));
 218        *header.typeflag = TYPEFLAG_EXT_HEADER;
 219        mode = 0100666;
 220        xsnprintf(header.name, sizeof(header.name), "%s.paxheader", sha1_to_hex(sha1));
 221        prepare_header(args, &header, mode, size);
 222        write_blocked(&header, sizeof(header));
 223        write_blocked(buffer, size);
 224        return 0;
 225}
 226
 227static int write_tar_entry(struct archiver_args *args,
 228                           const unsigned char *sha1,
 229                           const char *path, size_t pathlen,
 230                           unsigned int mode)
 231{
 232        struct ustar_header header;
 233        struct strbuf ext_header = STRBUF_INIT;
 234        unsigned int old_mode = mode;
 235        unsigned long size, size_in_header;
 236        void *buffer;
 237        int err = 0;
 238
 239        memset(&header, 0, sizeof(header));
 240
 241        if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 242                *header.typeflag = TYPEFLAG_DIR;
 243                mode = (mode | 0777) & ~tar_umask;
 244        } else if (S_ISLNK(mode)) {
 245                *header.typeflag = TYPEFLAG_LNK;
 246                mode |= 0777;
 247        } else if (S_ISREG(mode)) {
 248                *header.typeflag = TYPEFLAG_REG;
 249                mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 250        } else {
 251                return error("unsupported file mode: 0%o (SHA1: %s)",
 252                             mode, sha1_to_hex(sha1));
 253        }
 254        if (pathlen > sizeof(header.name)) {
 255                size_t plen = get_path_prefix(path, pathlen,
 256                                              sizeof(header.prefix));
 257                size_t rest = pathlen - plen - 1;
 258                if (plen > 0 && rest <= sizeof(header.name)) {
 259                        memcpy(header.prefix, path, plen);
 260                        memcpy(header.name, path + plen + 1, rest);
 261                } else {
 262                        xsnprintf(header.name, sizeof(header.name), "%s.data",
 263                                  sha1_to_hex(sha1));
 264                        strbuf_append_ext_header(&ext_header, "path",
 265                                                 path, pathlen);
 266                }
 267        } else
 268                memcpy(header.name, path, pathlen);
 269
 270        if (S_ISREG(mode) && !args->convert &&
 271            sha1_object_info(sha1, &size) == OBJ_BLOB &&
 272            size > big_file_threshold)
 273                buffer = NULL;
 274        else if (S_ISLNK(mode) || S_ISREG(mode)) {
 275                enum object_type type;
 276                buffer = sha1_file_to_archive(args, path, sha1, old_mode, &type, &size);
 277                if (!buffer)
 278                        return error("cannot read %s", sha1_to_hex(sha1));
 279        } else {
 280                buffer = NULL;
 281                size = 0;
 282        }
 283
 284        if (S_ISLNK(mode)) {
 285                if (size > sizeof(header.linkname)) {
 286                        xsnprintf(header.linkname, sizeof(header.linkname),
 287                                  "see %s.paxheader", sha1_to_hex(sha1));
 288                        strbuf_append_ext_header(&ext_header, "linkpath",
 289                                                 buffer, size);
 290                } else
 291                        memcpy(header.linkname, buffer, size);
 292        }
 293
 294        size_in_header = size;
 295        if (S_ISREG(mode) && size > USTAR_MAX_SIZE) {
 296                size_in_header = 0;
 297                strbuf_append_ext_header_uint(&ext_header, "size", size);
 298        }
 299
 300        prepare_header(args, &header, mode, size_in_header);
 301
 302        if (ext_header.len > 0) {
 303                err = write_extended_header(args, sha1, ext_header.buf,
 304                                            ext_header.len);
 305                if (err) {
 306                        free(buffer);
 307                        return err;
 308                }
 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}