archive-tar.c

   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
  12 static char block[BLOCKSIZE];
  13 static unsigned long offset;
  14
  15 static int tar_umask = 002;
  16
  17 static 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 */
  21 static 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  */
  33 static 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  */
  69 static 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  */
  86 static 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
 102 static 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
 115 static 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
 126 static int write_tar_entry(struct archiver_args *args,
 127                 const unsigned char *sha1, const char *path, size_t pathlen,
 128                 unsigned int mode, void *buffer, unsigned long size)
 129 {
 130         struct ustar_header header;
 131         struct strbuf ext_header = STRBUF_INIT;
 132         int err = 0;
 133
 134         memset(&header, 0, sizeof(header));
 135
 136         if (!sha1) {
 137                 *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 138                 mode = 0100666;
 139                 strcpy(header.name, "pax_global_header");
 140         } else if (!path) {
 141                 *header.typeflag = TYPEFLAG_EXT_HEADER;
 142                 mode = 0100666;
 143                 sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 144         } else {
 145                 if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 146                         *header.typeflag = TYPEFLAG_DIR;
 147                         mode = (mode | 0777) & ~tar_umask;
 148                 } else if (S_ISLNK(mode)) {
 149                         *header.typeflag = TYPEFLAG_LNK;
 150                         mode |= 0777;
 151                 } else if (S_ISREG(mode)) {
 152                         *header.typeflag = TYPEFLAG_REG;
 153                         mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 154                 } else {
 155                         return error("unsupported file mode: 0%o (SHA1: %s)",
 156                                         mode, sha1_to_hex(sha1));
 157                 }
 158                 if (pathlen > sizeof(header.name)) {
 159                         size_t plen = get_path_prefix(path, pathlen,
 160                                         sizeof(header.prefix));
 161                         size_t rest = pathlen - plen - 1;
 162                         if (plen > 0 && rest <= sizeof(header.name)) {
 163                                 memcpy(header.prefix, path, plen);
 164                                 memcpy(header.name, path + plen + 1, rest);
 165                         } else {
 166                                 sprintf(header.name, "%s.data",
 167                                         sha1_to_hex(sha1));
 168                                 strbuf_append_ext_header(&ext_header, "path",
 169                                                 path, pathlen);
 170                         }
 171                 } else
 172                         memcpy(header.name, path, pathlen);
 173         }
 174
 175         if (S_ISLNK(mode) && buffer) {
 176                 if (size > sizeof(header.linkname)) {
 177                         sprintf(header.linkname, "see %s.paxheader",
 178                                 sha1_to_hex(sha1));
 179                         strbuf_append_ext_header(&ext_header, "linkpath",
 180                                                  buffer, size);
 181                 } else
 182                         memcpy(header.linkname, buffer, size);
 183         }
 184
 185         sprintf(header.mode, "%07o", mode & 07777);
 186         sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 187         sprintf(header.mtime, "%011lo", (unsigned long) args->time);
 188
 189         sprintf(header.uid, "%07o", 0);
 190         sprintf(header.gid, "%07o", 0);
 191         strlcpy(header.uname, "root", sizeof(header.uname));
 192         strlcpy(header.gname, "root", sizeof(header.gname));
 193         sprintf(header.devmajor, "%07o", 0);
 194         sprintf(header.devminor, "%07o", 0);
 195
 196         memcpy(header.magic, "ustar", 6);
 197         memcpy(header.version, "00", 2);
 198
 199         sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 200
 201         if (ext_header.len > 0) {
 202                 err = write_tar_entry(args, sha1, NULL, 0, 0, ext_header.buf,
 203                                 ext_header.len);
 204                 if (err)
 205                         return err;
 206         }
 207         strbuf_release(&ext_header);
 208         write_blocked(&header, sizeof(header));
 209         if (S_ISREG(mode) && buffer && size > 0)
 210                 write_blocked(buffer, size);
 211         return err;
 212 }
 213
 214 static int write_global_extended_header(struct archiver_args *args)
 215 {
 216         const unsigned char *sha1 = args->commit_sha1;
 217         struct strbuf ext_header = STRBUF_INIT;
 218         int err;
 219
 220         strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 221         err = write_tar_entry(args, NULL, NULL, 0, 0, ext_header.buf,
 222                         ext_header.len);
 223         strbuf_release(&ext_header);
 224         return err;
 225 }
 226
 227 static struct archiver **tar_filters;
 228 static int nr_tar_filters;
 229 static int alloc_tar_filters;
 230
 231 static struct archiver *find_tar_filter(const char *name, int len)
 232 {
 233         int i;
 234         for (i = 0; i < nr_tar_filters; i++) {
 235                 struct archiver *ar = tar_filters[i];
 236                 if (!strncmp(ar->name, name, len) && !ar->name[len])
 237                         return ar;
 238         }
 239         return NULL;
 240 }
 241
 242 static int tar_filter_config(const char *var, const char *value, void *data)
 243 {
 244         struct archiver *ar;
 245         const char *dot;
 246         const char *name;
 247         const char *type;
 248         int namelen;
 249
 250         if (prefixcmp(var, "tar."))
 251                 return 0;
 252         dot = strrchr(var, '.');
 253         if (dot == var + 9)
 254                 return 0;
 255
 256         name = var + 4;
 257         namelen = dot - name;
 258         type = dot + 1;
 259
 260         ar = find_tar_filter(name, namelen);
 261         if (!ar) {
 262                 ar = xcalloc(1, sizeof(*ar));
 263                 ar->name = xmemdupz(name, namelen);
 264                 ar->write_archive = write_tar_filter_archive;
 265                 ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS;
 266                 ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
 267                 tar_filters[nr_tar_filters++] = ar;
 268         }
 269
 270         if (!strcmp(type, "command")) {
 271                 if (!value)
 272                         return config_error_nonbool(var);
 273                 free(ar->data);
 274                 ar->data = xstrdup(value);
 275                 return 0;
 276         }
 277         if (!strcmp(type, "remote")) {
 278                 if (git_config_bool(var, value))
 279                         ar->flags |= ARCHIVER_REMOTE;
 280                 else
 281                         ar->flags &= ~ARCHIVER_REMOTE;
 282                 return 0;
 283         }
 284
 285         return 0;
 286 }
 287
 288 static int git_tar_config(const char *var, const char *value, void *cb)
 289 {
 290         if (!strcmp(var, "tar.umask")) {
 291                 if (value && !strcmp(value, "user")) {
 292                         tar_umask = umask(0);
 293                         umask(tar_umask);
 294                 } else {
 295                         tar_umask = git_config_int(var, value);
 296                 }
 297                 return 0;
 298         }
 299
 300         return tar_filter_config(var, value, cb);
 301 }
 302
 303 static int write_tar_archive(const struct archiver *ar,
 304                              struct archiver_args *args)
 305 {
 306         int err = 0;
 307
 308         if (args->commit_sha1)
 309                 err = write_global_extended_header(args);
 310         if (!err)
 311                 err = write_archive_entries(args, write_tar_entry);
 312         if (!err)
 313                 write_trailer();
 314         return err;
 315 }
 316
 317 static int write_tar_filter_archive(const struct archiver *ar,
 318                                     struct archiver_args *args)
 319 {
 320         struct strbuf cmd = STRBUF_INIT;
 321         struct child_process filter;
 322         const char *argv[2];
 323         int r;
 324
 325         if (!ar->data)
 326                 die("BUG: tar-filter archiver called with no filter defined");
 327
 328         strbuf_addstr(&cmd, ar->data);
 329         if (args->compression_level >= 0)
 330                 strbuf_addf(&cmd, " -%d", args->compression_level);
 331
 332         memset(&filter, 0, sizeof(filter));
 333         argv[0] = cmd.buf;
 334         argv[1] = NULL;
 335         filter.argv = argv;
 336         filter.use_shell = 1;
 337         filter.in = -1;
 338
 339         if (start_command(&filter) < 0)
 340                 die_errno("unable to start '%s' filter", argv[0]);
 341         close(1);
 342         if (dup2(filter.in, 1) < 0)
 343                 die_errno("unable to redirect descriptor");
 344         close(filter.in);
 345
 346         r = write_tar_archive(ar, args);
 347
 348         close(1);
 349         if (finish_command(&filter) != 0)
 350                 die("'%s' filter reported error", argv[0]);
 351
 352         strbuf_release(&cmd);
 353         return r;
 354 }
 355
 356 static struct archiver tar_archiver = {
 357         "tar",
 358         write_tar_archive,
 359         ARCHIVER_REMOTE
 360 };
 361
 362 void init_tar_archiver(void)
 363 {
 364         int i;
 365         register_archiver(&tar_archiver);
 366
 367         tar_filter_config("tar.tgz.command", "gzip -cn", NULL);
 368         tar_filter_config("tar.tgz.remote", "true", NULL);
 369         tar_filter_config("tar.tar.gz.command", "gzip -cn", NULL);
 370         tar_filter_config("tar.tar.gz.remote", "true", NULL);
 371         git_config(git_tar_config, NULL);
 372         for (i = 0; i < nr_tar_filters; i++) {
 373                 /* omit any filters that never had a command configured */
 374                 if (tar_filters[i]->data)
 375                         register_archiver(tar_filters[i]);
 376         }
 377 }