6c8a0bd3bf524a962d18395e710a67e0358451b2
   1/*
   2 * Copyright (c) 2005, 2006 Rene Scharfe
   3 */
   4#include "cache.h"
   5#include "tar.h"
   6#include "archive.h"
   7#include "run-command.h"
   8
   9#define RECORDSIZE      (512)
  10#define BLOCKSIZE       (RECORDSIZE * 20)
  11
  12static char block[BLOCKSIZE];
  13static unsigned long offset;
  14
  15static int tar_umask = 002;
  16
  17static int write_tar_filter_archive(const struct archiver *ar,
  18                                    struct archiver_args *args);
  19
  20/* writes out the whole block, but only if it is full */
  21static void write_if_needed(void)
  22{
  23        if (offset == BLOCKSIZE) {
  24                write_or_die(1, block, BLOCKSIZE);
  25                offset = 0;
  26        }
  27}
  28
  29/*
  30 * queues up writes, so that all our write(2) calls write exactly one
  31 * full block; pads writes to RECORDSIZE
  32 */
  33static void write_blocked(const void *data, unsigned long size)
  34{
  35        const char *buf = data;
  36        unsigned long tail;
  37
  38        if (offset) {
  39                unsigned long chunk = BLOCKSIZE - offset;
  40                if (size < chunk)
  41                        chunk = size;
  42                memcpy(block + offset, buf, chunk);
  43                size -= chunk;
  44                offset += chunk;
  45                buf += chunk;
  46                write_if_needed();
  47        }
  48        while (size >= BLOCKSIZE) {
  49                write_or_die(1, buf, BLOCKSIZE);
  50                size -= BLOCKSIZE;
  51                buf += BLOCKSIZE;
  52        }
  53        if (size) {
  54                memcpy(block + offset, buf, size);
  55                offset += size;
  56        }
  57        tail = offset % RECORDSIZE;
  58        if (tail)  {
  59                memset(block + offset, 0, RECORDSIZE - tail);
  60                offset += RECORDSIZE - tail;
  61        }
  62        write_if_needed();
  63}
  64
  65/*
  66 * The end of tar archives is marked by 2*512 nul bytes and after that
  67 * follows the rest of the block (if any).
  68 */
  69static void write_trailer(void)
  70{
  71        int tail = BLOCKSIZE - offset;
  72        memset(block + offset, 0, tail);
  73        write_or_die(1, block, BLOCKSIZE);
  74        if (tail < 2 * RECORDSIZE) {
  75                memset(block, 0, offset);
  76                write_or_die(1, block, BLOCKSIZE);
  77        }
  78}
  79
  80/*
  81 * pax extended header records have the format "%u %s=%s\n".  %u contains
  82 * the size of the whole string (including the %u), the first %s is the
  83 * keyword, the second one is the value.  This function constructs such a
  84 * string and appends it to a struct strbuf.
  85 */
  86static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
  87                                     const char *value, unsigned int valuelen)
  88{
  89        int len, tmp;
  90
  91        /* "%u %s=%s\n" */
  92        len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
  93        for (tmp = len; tmp > 9; tmp /= 10)
  94                len++;
  95
  96        strbuf_grow(sb, len);
  97        strbuf_addf(sb, "%u %s=", len, keyword);
  98        strbuf_add(sb, value, valuelen);
  99        strbuf_addch(sb, '\n');
 100}
 101
 102static unsigned int ustar_header_chksum(const struct ustar_header *header)
 103{
 104        char *p = (char *)header;
 105        unsigned int chksum = 0;
 106        while (p < header->chksum)
 107                chksum += *p++;
 108        chksum += sizeof(header->chksum) * ' ';
 109        p += sizeof(header->chksum);
 110        while (p < (char *)header + sizeof(struct ustar_header))
 111                chksum += *p++;
 112        return chksum;
 113}
 114
 115static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
 116{
 117        size_t i = pathlen;
 118        if (i > maxlen)
 119                i = maxlen;
 120        do {
 121                i--;
 122        } while (i > 0 && path[i] != '/');
 123        return i;
 124}
 125
 126static void prepare_header(struct archiver_args *args,
 127                           struct ustar_header *header,
 128                           unsigned int mode, unsigned long size)
 129{
 130        sprintf(header->mode, "%07o", mode & 07777);
 131        sprintf(header->size, "%011lo", S_ISREG(mode) ? size : 0);
 132        sprintf(header->mtime, "%011lo", (unsigned long) args->time);
 133
 134        sprintf(header->uid, "%07o", 0);
 135        sprintf(header->gid, "%07o", 0);
 136        strlcpy(header->uname, "root", sizeof(header->uname));
 137        strlcpy(header->gname, "root", sizeof(header->gname));
 138        sprintf(header->devmajor, "%07o", 0);
 139        sprintf(header->devminor, "%07o", 0);
 140
 141        memcpy(header->magic, "ustar", 6);
 142        memcpy(header->version, "00", 2);
 143
 144        sprintf(header->chksum, "%07o", ustar_header_chksum(header));
 145}
 146
 147static int write_extended_header(struct archiver_args *args,
 148                                 const unsigned char *sha1,
 149                                 const void *buffer, unsigned long size)
 150{
 151        struct ustar_header header;
 152        unsigned int mode;
 153        memset(&header, 0, sizeof(header));
 154        *header.typeflag = TYPEFLAG_EXT_HEADER;
 155        mode = 0100666;
 156        sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 157        prepare_header(args, &header, mode, size);
 158        write_blocked(&header, sizeof(header));
 159        write_blocked(buffer, size);
 160        return 0;
 161}
 162
 163static int write_tar_entry(struct archiver_args *args,
 164                const unsigned char *sha1, const char *path, size_t pathlen,
 165                unsigned int mode, void *buffer, unsigned long size)
 166{
 167        struct ustar_header header;
 168        struct strbuf ext_header = STRBUF_INIT;
 169        int err = 0;
 170
 171        memset(&header, 0, sizeof(header));
 172
 173        if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 174                *header.typeflag = TYPEFLAG_DIR;
 175                mode = (mode | 0777) & ~tar_umask;
 176        } else if (S_ISLNK(mode)) {
 177                *header.typeflag = TYPEFLAG_LNK;
 178                mode |= 0777;
 179        } else if (S_ISREG(mode)) {
 180                *header.typeflag = TYPEFLAG_REG;
 181                mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 182        } else {
 183                return error("unsupported file mode: 0%o (SHA1: %s)",
 184                             mode, sha1_to_hex(sha1));
 185        }
 186        if (pathlen > sizeof(header.name)) {
 187                size_t plen = get_path_prefix(path, pathlen,
 188                                              sizeof(header.prefix));
 189                size_t rest = pathlen - plen - 1;
 190                if (plen > 0 && rest <= sizeof(header.name)) {
 191                        memcpy(header.prefix, path, plen);
 192                                memcpy(header.name, path + plen + 1, rest);
 193                } else {
 194                        sprintf(header.name, "%s.data",
 195                                sha1_to_hex(sha1));
 196                        strbuf_append_ext_header(&ext_header, "path",
 197                                                 path, pathlen);
 198                }
 199        } else
 200                memcpy(header.name, path, pathlen);
 201
 202        if (S_ISLNK(mode) && buffer) {
 203                if (size > sizeof(header.linkname)) {
 204                        sprintf(header.linkname, "see %s.paxheader",
 205                                sha1_to_hex(sha1));
 206                        strbuf_append_ext_header(&ext_header, "linkpath",
 207                                                 buffer, size);
 208                } else
 209                        memcpy(header.linkname, buffer, size);
 210        }
 211
 212        prepare_header(args, &header, mode, size);
 213
 214        if (ext_header.len > 0) {
 215                err = write_extended_header(args, sha1, ext_header.buf,
 216                                            ext_header.len);
 217                if (err)
 218                        return err;
 219        }
 220        strbuf_release(&ext_header);
 221        write_blocked(&header, sizeof(header));
 222        if (S_ISREG(mode) && buffer && size > 0)
 223                write_blocked(buffer, size);
 224        return err;
 225}
 226
 227static int write_global_extended_header(struct archiver_args *args)
 228{
 229        const unsigned char *sha1 = args->commit_sha1;
 230        struct strbuf ext_header = STRBUF_INIT;
 231        struct ustar_header header;
 232        unsigned int mode;
 233        int err = 0;
 234
 235        strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 236        memset(&header, 0, sizeof(header));
 237        *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 238        mode = 0100666;
 239        strcpy(header.name, "pax_global_header");
 240        prepare_header(args, &header, mode, ext_header.len);
 241        write_blocked(&header, sizeof(header));
 242        write_blocked(ext_header.buf, ext_header.len);
 243        strbuf_release(&ext_header);
 244        return err;
 245}
 246
 247static struct archiver **tar_filters;
 248static int nr_tar_filters;
 249static int alloc_tar_filters;
 250
 251static struct archiver *find_tar_filter(const char *name, int len)
 252{
 253        int i;
 254        for (i = 0; i < nr_tar_filters; i++) {
 255                struct archiver *ar = tar_filters[i];
 256                if (!strncmp(ar->name, name, len) && !ar->name[len])
 257                        return ar;
 258        }
 259        return NULL;
 260}
 261
 262static int tar_filter_config(const char *var, const char *value, void *data)
 263{
 264        struct archiver *ar;
 265        const char *dot;
 266        const char *name;
 267        const char *type;
 268        int namelen;
 269
 270        if (prefixcmp(var, "tar."))
 271                return 0;
 272        dot = strrchr(var, '.');
 273        if (dot == var + 9)
 274                return 0;
 275
 276        name = var + 4;
 277        namelen = dot - name;
 278        type = dot + 1;
 279
 280        ar = find_tar_filter(name, namelen);
 281        if (!ar) {
 282                ar = xcalloc(1, sizeof(*ar));
 283                ar->name = xmemdupz(name, namelen);
 284                ar->write_archive = write_tar_filter_archive;
 285                ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS;
 286                ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
 287                tar_filters[nr_tar_filters++] = ar;
 288        }
 289
 290        if (!strcmp(type, "command")) {
 291                if (!value)
 292                        return config_error_nonbool(var);
 293                free(ar->data);
 294                ar->data = xstrdup(value);
 295                return 0;
 296        }
 297        if (!strcmp(type, "remote")) {
 298                if (git_config_bool(var, value))
 299                        ar->flags |= ARCHIVER_REMOTE;
 300                else
 301                        ar->flags &= ~ARCHIVER_REMOTE;
 302                return 0;
 303        }
 304
 305        return 0;
 306}
 307
 308static int git_tar_config(const char *var, const char *value, void *cb)
 309{
 310        if (!strcmp(var, "tar.umask")) {
 311                if (value && !strcmp(value, "user")) {
 312                        tar_umask = umask(0);
 313                        umask(tar_umask);
 314                } else {
 315                        tar_umask = git_config_int(var, value);
 316                }
 317                return 0;
 318        }
 319
 320        return tar_filter_config(var, value, cb);
 321}
 322
 323static int write_tar_archive(const struct archiver *ar,
 324                             struct archiver_args *args)
 325{
 326        int err = 0;
 327
 328        if (args->commit_sha1)
 329                err = write_global_extended_header(args);
 330        if (!err)
 331                err = write_archive_entries(args, write_tar_entry);
 332        if (!err)
 333                write_trailer();
 334        return err;
 335}
 336
 337static int write_tar_filter_archive(const struct archiver *ar,
 338                                    struct archiver_args *args)
 339{
 340        struct strbuf cmd = STRBUF_INIT;
 341        struct child_process filter;
 342        const char *argv[2];
 343        int r;
 344
 345        if (!ar->data)
 346                die("BUG: tar-filter archiver called with no filter defined");
 347
 348        strbuf_addstr(&cmd, ar->data);
 349        if (args->compression_level >= 0)
 350                strbuf_addf(&cmd, " -%d", args->compression_level);
 351
 352        memset(&filter, 0, sizeof(filter));
 353        argv[0] = cmd.buf;
 354        argv[1] = NULL;
 355        filter.argv = argv;
 356        filter.use_shell = 1;
 357        filter.in = -1;
 358
 359        if (start_command(&filter) < 0)
 360                die_errno("unable to start '%s' filter", argv[0]);
 361        close(1);
 362        if (dup2(filter.in, 1) < 0)
 363                die_errno("unable to redirect descriptor");
 364        close(filter.in);
 365
 366        r = write_tar_archive(ar, args);
 367
 368        close(1);
 369        if (finish_command(&filter) != 0)
 370                die("'%s' filter reported error", argv[0]);
 371
 372        strbuf_release(&cmd);
 373        return r;
 374}
 375
 376static struct archiver tar_archiver = {
 377        "tar",
 378        write_tar_archive,
 379        ARCHIVER_REMOTE
 380};
 381
 382void init_tar_archiver(void)
 383{
 384        int i;
 385        register_archiver(&tar_archiver);
 386
 387        tar_filter_config("tar.tgz.command", "gzip -cn", NULL);
 388        tar_filter_config("tar.tgz.remote", "true", NULL);
 389        tar_filter_config("tar.tar.gz.command", "gzip -cn", NULL);
 390        tar_filter_config("tar.tar.gz.remote", "true", NULL);
 391        git_config(git_tar_config, NULL);
 392        for (i = 0; i < nr_tar_filters; i++) {
 393                /* omit any filters that never had a command configured */
 394                if (tar_filters[i]->data)
 395                        register_archiver(tar_filters[i]);
 396        }
 397}