builtin-tar-tree.c

   1 /*
   2  * Copyright (c) 2005, 2006 Rene Scharfe
   3  */
   4 #include <time.h>
   5 #include "cache.h"
   6 #include "tree-walk.h"
   7 #include "commit.h"
   8 #include "strbuf.h"
   9 #include "tar.h"
  10 #include "builtin.h"
  11 #include "pkt-line.h"
  12
  13 #define RECORDSIZE      (512)
  14 #define BLOCKSIZE       (RECORDSIZE * 20)
  15
  16 static const char tar_tree_usage[] =
  17 "git-tar-tree [--remote=<repo>] <ent> [basedir]";
  18
  19 static char block[BLOCKSIZE];
  20 static unsigned long offset;
  21
  22 static time_t archive_time;
  23
  24 /* tries hard to write, either succeeds or dies in the attempt */
  25 static void reliable_write(void *buf, unsigned long size)
  26 {
  27         while (size > 0) {
  28                 long ret = xwrite(1, buf, size);
  29                 if (ret < 0) {
  30                         if (errno == EPIPE)
  31                                 exit(0);
  32                         die("git-tar-tree: %s", strerror(errno));
  33                 } else if (!ret) {
  34                         die("git-tar-tree: disk full?");
  35                 }
  36                 size -= ret;
  37                 buf += ret;
  38         }
  39 }
  40
  41 /* writes out the whole block, but only if it is full */
  42 static void write_if_needed(void)
  43 {
  44         if (offset == BLOCKSIZE) {
  45                 reliable_write(block, BLOCKSIZE);
  46                 offset = 0;
  47         }
  48 }
  49
  50 /*
  51  * queues up writes, so that all our write(2) calls write exactly one
  52  * full block; pads writes to RECORDSIZE
  53  */
  54 static void write_blocked(void *buf, unsigned long size)
  55 {
  56         unsigned long tail;
  57
  58         if (offset) {
  59                 unsigned long chunk = BLOCKSIZE - offset;
  60                 if (size < chunk)
  61                         chunk = size;
  62                 memcpy(block + offset, buf, chunk);
  63                 size -= chunk;
  64                 offset += chunk;
  65                 buf += chunk;
  66                 write_if_needed();
  67         }
  68         while (size >= BLOCKSIZE) {
  69                 reliable_write(buf, BLOCKSIZE);
  70                 size -= BLOCKSIZE;
  71                 buf += BLOCKSIZE;
  72         }
  73         if (size) {
  74                 memcpy(block + offset, buf, size);
  75                 offset += size;
  76         }
  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
  85 /*
  86  * The end of tar archives is marked by 2*512 nul bytes and after that
  87  * follows the rest of the block (if any).
  88  */
  89 static void write_trailer(void)
  90 {
  91         int tail = BLOCKSIZE - offset;
  92         memset(block + offset, 0, tail);
  93         reliable_write(block, BLOCKSIZE);
  94         if (tail < 2 * RECORDSIZE) {
  95                 memset(block, 0, offset);
  96                 reliable_write(block, BLOCKSIZE);
  97         }
  98 }
  99
 100 static void strbuf_append_string(struct strbuf *sb, const char *s)
 101 {
 102         int slen = strlen(s);
 103         int total = sb->len + slen;
 104         if (total > sb->alloc) {
 105                 sb->buf = xrealloc(sb->buf, total);
 106                 sb->alloc = total;
 107         }
 108         memcpy(sb->buf + sb->len, s, slen);
 109         sb->len = total;
 110 }
 111
 112 /*
 113  * pax extended header records have the format "%u %s=%s\n".  %u contains
 114  * the size of the whole string (including the %u), the first %s is the
 115  * keyword, the second one is the value.  This function constructs such a
 116  * string and appends it to a struct strbuf.
 117  */
 118 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 119                                      const char *value, unsigned int valuelen)
 120 {
 121         char *p;
 122         int len, total, tmp;
 123
 124         /* "%u %s=%s\n" */
 125         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 126         for (tmp = len; tmp > 9; tmp /= 10)
 127                 len++;
 128
 129         total = sb->len + len;
 130         if (total > sb->alloc) {
 131                 sb->buf = xrealloc(sb->buf, total);
 132                 sb->alloc = total;
 133         }
 134
 135         p = sb->buf;
 136         p += sprintf(p, "%u %s=", len, keyword);
 137         memcpy(p, value, valuelen);
 138         p += valuelen;
 139         *p = '\n';
 140         sb->len = total;
 141 }
 142
 143 static unsigned int ustar_header_chksum(const struct ustar_header *header)
 144 {
 145         char *p = (char *)header;
 146         unsigned int chksum = 0;
 147         while (p < header->chksum)
 148                 chksum += *p++;
 149         chksum += sizeof(header->chksum) * ' ';
 150         p += sizeof(header->chksum);
 151         while (p < (char *)header + sizeof(struct ustar_header))
 152                 chksum += *p++;
 153         return chksum;
 154 }
 155
 156 static int get_path_prefix(const struct strbuf *path, int maxlen)
 157 {
 158         int i = path->len;
 159         if (i > maxlen)
 160                 i = maxlen;
 161         do {
 162                 i--;
 163         } while (i > 0 && path->buf[i] != '/');
 164         return i;
 165 }
 166
 167 static void write_entry(const unsigned char *sha1, struct strbuf *path,
 168                         unsigned int mode, void *buffer, unsigned long size)
 169 {
 170         struct ustar_header header;
 171         struct strbuf ext_header;
 172
 173         memset(&header, 0, sizeof(header));
 174         ext_header.buf = NULL;
 175         ext_header.len = ext_header.alloc = 0;
 176
 177         if (!sha1) {
 178                 *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 179                 mode = 0100666;
 180                 strcpy(header.name, "pax_global_header");
 181         } else if (!path) {
 182                 *header.typeflag = TYPEFLAG_EXT_HEADER;
 183                 mode = 0100666;
 184                 sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 185         } else {
 186                 if (S_ISDIR(mode)) {
 187                         *header.typeflag = TYPEFLAG_DIR;
 188                         mode |= 0777;
 189                 } else if (S_ISLNK(mode)) {
 190                         *header.typeflag = TYPEFLAG_LNK;
 191                         mode |= 0777;
 192                 } else if (S_ISREG(mode)) {
 193                         *header.typeflag = TYPEFLAG_REG;
 194                         mode |= (mode & 0100) ? 0777 : 0666;
 195                 } else {
 196                         error("unsupported file mode: 0%o (SHA1: %s)",
 197                               mode, sha1_to_hex(sha1));
 198                         return;
 199                 }
 200                 if (path->len > sizeof(header.name)) {
 201                         int plen = get_path_prefix(path, sizeof(header.prefix));
 202                         int rest = path->len - plen - 1;
 203                         if (plen > 0 && rest <= sizeof(header.name)) {
 204                                 memcpy(header.prefix, path->buf, plen);
 205                                 memcpy(header.name, path->buf + plen + 1, rest);
 206                         } else {
 207                                 sprintf(header.name, "%s.data",
 208                                         sha1_to_hex(sha1));
 209                                 strbuf_append_ext_header(&ext_header, "path",
 210                                                          path->buf, path->len);
 211                         }
 212                 } else
 213                         memcpy(header.name, path->buf, path->len);
 214         }
 215
 216         if (S_ISLNK(mode) && buffer) {
 217                 if (size > sizeof(header.linkname)) {
 218                         sprintf(header.linkname, "see %s.paxheader",
 219                                 sha1_to_hex(sha1));
 220                         strbuf_append_ext_header(&ext_header, "linkpath",
 221                                                  buffer, size);
 222                 } else
 223                         memcpy(header.linkname, buffer, size);
 224         }
 225
 226         sprintf(header.mode, "%07o", mode & 07777);
 227         sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 228         sprintf(header.mtime, "%011lo", archive_time);
 229
 230         /* XXX: should we provide more meaningful info here? */
 231         sprintf(header.uid, "%07o", 0);
 232         sprintf(header.gid, "%07o", 0);
 233         safe_strncpy(header.uname, "git", sizeof(header.uname));
 234         safe_strncpy(header.gname, "git", sizeof(header.gname));
 235         sprintf(header.devmajor, "%07o", 0);
 236         sprintf(header.devminor, "%07o", 0);
 237
 238         memcpy(header.magic, "ustar", 6);
 239         memcpy(header.version, "00", 2);
 240
 241         sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 242
 243         if (ext_header.len > 0) {
 244                 write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
 245                 free(ext_header.buf);
 246         }
 247         write_blocked(&header, sizeof(header));
 248         if (S_ISREG(mode) && buffer && size > 0)
 249                 write_blocked(buffer, size);
 250 }
 251
 252 static void write_global_extended_header(const unsigned char *sha1)
 253 {
 254         struct strbuf ext_header;
 255         ext_header.buf = NULL;
 256         ext_header.len = ext_header.alloc = 0;
 257         strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 258         write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
 259         free(ext_header.buf);
 260 }
 261
 262 static void traverse_tree(struct tree_desc *tree, struct strbuf *path)
 263 {
 264         int pathlen = path->len;
 265         struct name_entry entry;
 266
 267         while (tree_entry(tree, &entry)) {
 268                 void *eltbuf;
 269                 char elttype[20];
 270                 unsigned long eltsize;
 271
 272                 eltbuf = read_sha1_file(entry.sha1, elttype, &eltsize);
 273                 if (!eltbuf)
 274                         die("cannot read %s", sha1_to_hex(entry.sha1));
 275
 276                 path->len = pathlen;
 277                 strbuf_append_string(path, entry.path);
 278                 if (S_ISDIR(entry.mode))
 279                         strbuf_append_string(path, "/");
 280
 281                 write_entry(entry.sha1, path, entry.mode, eltbuf, eltsize);
 282
 283                 if (S_ISDIR(entry.mode)) {
 284                         struct tree_desc subtree;
 285                         subtree.buf = eltbuf;
 286                         subtree.size = eltsize;
 287                         traverse_tree(&subtree, path);
 288                 }
 289                 free(eltbuf);
 290         }
 291 }
 292
 293 static int generate_tar(int argc, const char **argv, char** envp)
 294 {
 295         unsigned char sha1[20], tree_sha1[20];
 296         struct commit *commit;
 297         struct tree_desc tree;
 298         struct strbuf current_path;
 299
 300         current_path.buf = xmalloc(PATH_MAX);
 301         current_path.alloc = PATH_MAX;
 302         current_path.len = current_path.eof = 0;
 303
 304         setup_git_directory();
 305         git_config(git_default_config);
 306
 307         switch (argc) {
 308         case 3:
 309                 strbuf_append_string(&current_path, argv[2]);
 310                 strbuf_append_string(&current_path, "/");
 311                 /* FALLTHROUGH */
 312         case 2:
 313                 if (get_sha1(argv[1], sha1))
 314                         die("Not a valid object name %s", argv[1]);
 315                 break;
 316         default:
 317                 usage(tar_tree_usage);
 318         }
 319
 320         commit = lookup_commit_reference_gently(sha1, 1);
 321         if (commit) {
 322                 write_global_extended_header(commit->object.sha1);
 323                 archive_time = commit->date;
 324         } else
 325                 archive_time = time(NULL);
 326
 327         tree.buf = read_object_with_reference(sha1, tree_type, &tree.size,
 328                                               tree_sha1);
 329         if (!tree.buf)
 330                 die("not a reference to a tag, commit or tree object: %s",
 331                     sha1_to_hex(sha1));
 332
 333         if (current_path.len > 0)
 334                 write_entry(tree_sha1, &current_path, 040777, NULL, 0);
 335         traverse_tree(&tree, &current_path);
 336         write_trailer();
 337         free(current_path.buf);
 338         return 0;
 339 }
 340
 341 static const char *exec = "git-upload-tar";
 342
 343 static int remote_tar(int argc, const char **argv)
 344 {
 345         int fd[2], ret, len;
 346         pid_t pid;
 347         char buf[1024];
 348         char *url;
 349
 350         if (argc < 3 || 4 < argc)
 351                 usage(tar_tree_usage);
 352
 353         /* --remote=<repo> */
 354         url = strdup(argv[1]+9);
 355         pid = git_connect(fd, url, exec);
 356         if (pid < 0)
 357                 return 1;
 358
 359         packet_write(fd[1], "want %s\n", argv[2]);
 360         if (argv[3])
 361                 packet_write(fd[1], "base %s\n", argv[3]);
 362         packet_flush(fd[1]);
 363
 364         len = packet_read_line(fd[0], buf, sizeof(buf));
 365         if (!len)
 366                 die("git-tar-tree: expected ACK/NAK, got EOF");
 367         if (buf[len-1] == '\n')
 368                 buf[--len] = 0;
 369         if (strcmp(buf, "ACK")) {
 370                 if (5 < len && !strncmp(buf, "NACK ", 5))
 371                         die("git-tar-tree: NACK %s", buf + 5);
 372                 die("git-tar-tree: protocol error");
 373         }
 374         /* expect a flush */
 375         len = packet_read_line(fd[0], buf, sizeof(buf));
 376         if (len)
 377                 die("git-tar-tree: expected a flush");
 378
 379         /* Now, start reading from fd[0] and spit it out to stdout */
 380         ret = copy_fd(fd[0], 1);
 381         close(fd[0]);
 382
 383         ret |= finish_connect(pid);
 384         return !!ret;
 385 }
 386
 387 int cmd_tar_tree(int argc, const char **argv, char **envp)
 388 {
 389         if (argc < 2)
 390                 usage(tar_tree_usage);
 391         if (!strncmp("--remote=", argv[1], 9))
 392                 return remote_tar(argc, argv);
 393         return generate_tar(argc, argv, envp);
 394 }
 395
 396 /* ustar header + extended global header content */
 397 #define HEADERSIZE (2 * RECORDSIZE)
 398
 399 int cmd_get_tar_commit_id(int argc, const char **argv, char **envp)
 400 {
 401         char buffer[HEADERSIZE];
 402         struct ustar_header *header = (struct ustar_header *)buffer;
 403         char *content = buffer + RECORDSIZE;
 404         ssize_t n;
 405
 406         n = xread(0, buffer, HEADERSIZE);
 407         if (n < HEADERSIZE)
 408                 die("git-get-tar-commit-id: read error");
 409         if (header->typeflag[0] != 'g')
 410                 return 1;
 411         if (memcmp(content, "52 comment=", 11))
 412                 return 1;
 413
 414         n = xwrite(1, content + 11, 41);
 415         if (n < 41)
 416                 die("git-get-tar-commit-id: write error");
 417
 418         return 0;
 419 }