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 > 1 && path[i - 1] == '/')
 119                 i--;
 120         if (i > maxlen)
 121                 i = maxlen;
 122         do {
 123                 i--;
 124         } while (i > 0 && path[i] != '/');
 125         return i;
 126 }
 127
 128 static int write_tar_entry(struct archiver_args *args,
 129                 const unsigned char *sha1, const char *path, size_t pathlen,
 130                 unsigned int mode, void *buffer, unsigned long size)
 131 {
 132         struct ustar_header header;
 133         struct strbuf ext_header = STRBUF_INIT;
 134         int err = 0;
 135
 136         memset(&header, 0, sizeof(header));
 137
 138         if (!sha1) {
 139                 *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 140                 mode = 0100666;
 141                 strcpy(header.name, "pax_global_header");
 142         } else if (!path) {
 143                 *header.typeflag = TYPEFLAG_EXT_HEADER;
 144                 mode = 0100666;
 145                 sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 146         } else {
 147                 if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 148                         *header.typeflag = TYPEFLAG_DIR;
 149                         mode = (mode | 0777) & ~tar_umask;
 150                 } else if (S_ISLNK(mode)) {
 151                         *header.typeflag = TYPEFLAG_LNK;
 152                         mode |= 0777;
 153                 } else if (S_ISREG(mode)) {
 154                         *header.typeflag = TYPEFLAG_REG;
 155                         mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 156                 } else {
 157                         return error("unsupported file mode: 0%o (SHA1: %s)",
 158                                         mode, sha1_to_hex(sha1));
 159                 }
 160                 if (pathlen > sizeof(header.name)) {
 161                         size_t plen = get_path_prefix(path, pathlen,
 162                                         sizeof(header.prefix));
 163                         size_t rest = pathlen - plen - 1;
 164                         if (plen > 0 && rest <= sizeof(header.name)) {
 165                                 memcpy(header.prefix, path, plen);
 166                                 memcpy(header.name, path + plen + 1, rest);
 167                         } else {
 168                                 sprintf(header.name, "%s.data",
 169                                         sha1_to_hex(sha1));
 170                                 strbuf_append_ext_header(&ext_header, "path",
 171                                                 path, pathlen);
 172                         }
 173                 } else
 174                         memcpy(header.name, path, pathlen);
 175         }
 176
 177         if (S_ISLNK(mode) && buffer) {
 178                 if (size > sizeof(header.linkname)) {
 179                         sprintf(header.linkname, "see %s.paxheader",
 180                                 sha1_to_hex(sha1));
 181                         strbuf_append_ext_header(&ext_header, "linkpath",
 182                                                  buffer, size);
 183                 } else
 184                         memcpy(header.linkname, buffer, size);
 185         }
 186
 187         sprintf(header.mode, "%07o", mode & 07777);
 188         sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 189         sprintf(header.mtime, "%011lo", (unsigned long) args->time);
 190
 191         sprintf(header.uid, "%07o", 0);
 192         sprintf(header.gid, "%07o", 0);
 193         strlcpy(header.uname, "root", sizeof(header.uname));
 194         strlcpy(header.gname, "root", sizeof(header.gname));
 195         sprintf(header.devmajor, "%07o", 0);
 196         sprintf(header.devminor, "%07o", 0);
 197
 198         memcpy(header.magic, "ustar", 6);
 199         memcpy(header.version, "00", 2);
 200
 201         sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 202
 203         if (ext_header.len > 0) {
 204                 err = write_tar_entry(args, sha1, NULL, 0, 0, ext_header.buf,
 205                                 ext_header.len);
 206                 if (err)
 207                         return err;
 208         }
 209         strbuf_release(&ext_header);
 210         write_blocked(&header, sizeof(header));
 211         if (S_ISREG(mode) && buffer && size > 0)
 212                 write_blocked(buffer, size);
 213         return err;
 214 }
 215
 216 static int write_global_extended_header(struct archiver_args *args)
 217 {
 218         const unsigned char *sha1 = args->commit_sha1;
 219         struct strbuf ext_header = STRBUF_INIT;
 220         int err;
 221
 222         strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 223         err = write_tar_entry(args, NULL, NULL, 0, 0, ext_header.buf,
 224                         ext_header.len);
 225         strbuf_release(&ext_header);
 226         return err;
 227 }
 228
 229 static struct archiver **tar_filters;
 230 static int nr_tar_filters;
 231 static int alloc_tar_filters;
 232
 233 static struct archiver *find_tar_filter(const char *name, int len)
 234 {
 235         int i;
 236         for (i = 0; i < nr_tar_filters; i++) {
 237                 struct archiver *ar = tar_filters[i];
 238                 if (!strncmp(ar->name, name, len) && !ar->name[len])
 239                         return ar;
 240         }
 241         return NULL;
 242 }
 243
 244 static int tar_filter_config(const char *var, const char *value, void *data)
 245 {
 246         struct archiver *ar;
 247         const char *dot;
 248         const char *name;
 249         const char *type;
 250         int namelen;
 251
 252         if (prefixcmp(var, "tar."))
 253                 return 0;
 254         dot = strrchr(var, '.');
 255         if (dot == var + 9)
 256                 return 0;
 257
 258         name = var + 4;
 259         namelen = dot - name;
 260         type = dot + 1;
 261
 262         ar = find_tar_filter(name, namelen);
 263         if (!ar) {
 264                 ar = xcalloc(1, sizeof(*ar));
 265                 ar->name = xmemdupz(name, namelen);
 266                 ar->write_archive = write_tar_filter_archive;
 267                 ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS;
 268                 ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
 269                 tar_filters[nr_tar_filters++] = ar;
 270         }
 271
 272         if (!strcmp(type, "command")) {
 273                 if (!value)
 274                         return config_error_nonbool(var);
 275                 free(ar->data);
 276                 ar->data = xstrdup(value);
 277                 return 0;
 278         }
 279         if (!strcmp(type, "remote")) {
 280                 if (git_config_bool(var, value))
 281                         ar->flags |= ARCHIVER_REMOTE;
 282                 else
 283                         ar->flags &= ~ARCHIVER_REMOTE;
 284                 return 0;
 285         }
 286
 287         return 0;
 288 }
 289
 290 static int git_tar_config(const char *var, const char *value, void *cb)
 291 {
 292         if (!strcmp(var, "tar.umask")) {
 293                 if (value && !strcmp(value, "user")) {
 294                         tar_umask = umask(0);
 295                         umask(tar_umask);
 296                 } else {
 297                         tar_umask = git_config_int(var, value);
 298                 }
 299                 return 0;
 300         }
 301
 302         return tar_filter_config(var, value, cb);
 303 }
 304
 305 static int write_tar_archive(const struct archiver *ar,
 306                              struct archiver_args *args)
 307 {
 308         int err = 0;
 309
 310         if (args->commit_sha1)
 311                 err = write_global_extended_header(args);
 312         if (!err)
 313                 err = write_archive_entries(args, write_tar_entry);
 314         if (!err)
 315                 write_trailer();
 316         return err;
 317 }
 318
 319 static int write_tar_filter_archive(const struct archiver *ar,
 320                                     struct archiver_args *args)
 321 {
 322         struct strbuf cmd = STRBUF_INIT;
 323         struct child_process filter;
 324         const char *argv[2];
 325         int r;
 326
 327         if (!ar->data)
 328                 die("BUG: tar-filter archiver called with no filter defined");
 329
 330         strbuf_addstr(&cmd, ar->data);
 331         if (args->compression_level >= 0)
 332                 strbuf_addf(&cmd, " -%d", args->compression_level);
 333
 334         memset(&filter, 0, sizeof(filter));
 335         argv[0] = cmd.buf;
 336         argv[1] = NULL;
 337         filter.argv = argv;
 338         filter.use_shell = 1;
 339         filter.in = -1;
 340
 341         if (start_command(&filter) < 0)
 342                 die_errno("unable to start '%s' filter", argv[0]);
 343         close(1);
 344         if (dup2(filter.in, 1) < 0)
 345                 die_errno("unable to redirect descriptor");
 346         close(filter.in);
 347
 348         r = write_tar_archive(ar, args);
 349
 350         close(1);
 351         if (finish_command(&filter) != 0)
 352                 die("'%s' filter reported error", argv[0]);
 353
 354         strbuf_release(&cmd);
 355         return r;
 356 }
 357
 358 static struct archiver tar_archiver = {
 359         "tar",
 360         write_tar_archive,
 361         ARCHIVER_REMOTE
 362 };
 363
 364 void init_tar_archiver(void)
 365 {
 366         int i;
 367         register_archiver(&tar_archiver);
 368
 369         tar_filter_config("tar.tgz.command", "gzip -cn", NULL);
 370         tar_filter_config("tar.tgz.remote", "true", NULL);
 371         tar_filter_config("tar.tar.gz.command", "gzip -cn", NULL);
 372         tar_filter_config("tar.tar.gz.remote", "true", NULL);
 373         git_config(git_tar_config, NULL);
 374         for (i = 0; i < nr_tar_filters; i++) {
 375                 /* omit any filters that never had a command configured */
 376                 if (tar_filters[i]->data)
 377                         register_archiver(tar_filters[i]);
 378         }
 379 }