Andrew's git - gitweb.git/blob - 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
  16static const char tar_tree_usage[] =
  17"git-tar-tree [--remote=<repo>] <ent> [basedir]";
  18
  19static char block[BLOCKSIZE];
  20static unsigned long offset;
  21
  22static time_t archive_time;
  23static int tar_umask;
  24
  25/* tries hard to write, either succeeds or dies in the attempt */
  26static void reliable_write(const void *data, unsigned long size)
  27{
  28        const char *buf = data;
  29
  30        while (size > 0) {
  31                long ret = xwrite(1, buf, size);
  32                if (ret < 0) {
  33                        if (errno == EPIPE)
  34                                exit(0);
  35                        die("git-tar-tree: %s", strerror(errno));
  36                } else if (!ret) {
  37                        die("git-tar-tree: disk full?");
  38                }
  39                size -= ret;
  40                buf += ret;
  41        }
  42}
  43
  44/* writes out the whole block, but only if it is full */
  45static void write_if_needed(void)
  46{
  47        if (offset == BLOCKSIZE) {
  48                reliable_write(block, BLOCKSIZE);
  49                offset = 0;
  50        }
  51}
  52
  53/*
  54 * queues up writes, so that all our write(2) calls write exactly one
  55 * full block; pads writes to RECORDSIZE
  56 */
  57static void write_blocked(const void *data, unsigned long size)
  58{
  59        const char *buf = data;
  60        unsigned long tail;
  61
  62        if (offset) {
  63                unsigned long chunk = BLOCKSIZE - offset;
  64                if (size < chunk)
  65                        chunk = size;
  66                memcpy(block + offset, buf, chunk);
  67                size -= chunk;
  68                offset += chunk;
  69                buf += chunk;
  70                write_if_needed();
  71        }
  72        while (size >= BLOCKSIZE) {
  73                reliable_write(buf, BLOCKSIZE);
  74                size -= BLOCKSIZE;
  75                buf += BLOCKSIZE;
  76        }
  77        if (size) {
  78                memcpy(block + offset, buf, size);
  79                offset += size;
  80        }
  81        tail = offset % RECORDSIZE;
  82        if (tail)  {
  83                memset(block + offset, 0, RECORDSIZE - tail);
  84                offset += RECORDSIZE - tail;
  85        }
  86        write_if_needed();
  87}
  88
  89/*
  90 * The end of tar archives is marked by 2*512 nul bytes and after that
  91 * follows the rest of the block (if any).
  92 */
  93static void write_trailer(void)
  94{
  95        int tail = BLOCKSIZE - offset;
  96        memset(block + offset, 0, tail);
  97        reliable_write(block, BLOCKSIZE);
  98        if (tail < 2 * RECORDSIZE) {
  99                memset(block, 0, offset);
 100                reliable_write(block, BLOCKSIZE);
 101        }
 102}
 103
 104static void strbuf_append_string(struct strbuf *sb, const char *s)
 105{
 106        int slen = strlen(s);
 107        int total = sb->len + slen;
 108        if (total > sb->alloc) {
 109                sb->buf = xrealloc(sb->buf, total);
 110                sb->alloc = total;
 111        }
 112        memcpy(sb->buf + sb->len, s, slen);
 113        sb->len = total;
 114}
 115
 116/*
 117 * pax extended header records have the format "%u %s=%s\n".  %u contains
 118 * the size of the whole string (including the %u), the first %s is the
 119 * keyword, the second one is the value.  This function constructs such a
 120 * string and appends it to a struct strbuf.
 121 */
 122static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 123                                     const char *value, unsigned int valuelen)
 124{
 125        char *p;
 126        int len, total, tmp;
 127
 128        /* "%u %s=%s\n" */
 129        len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 130        for (tmp = len; tmp > 9; tmp /= 10)
 131                len++;
 132
 133        total = sb->len + len;
 134        if (total > sb->alloc) {
 135                sb->buf = xrealloc(sb->buf, total);
 136                sb->alloc = total;
 137        }
 138
 139        p = sb->buf;
 140        p += sprintf(p, "%u %s=", len, keyword);
 141        memcpy(p, value, valuelen);
 142        p += valuelen;
 143        *p = '\n';
 144        sb->len = total;
 145}
 146
 147static unsigned int ustar_header_chksum(const struct ustar_header *header)
 148{
 149        char *p = (char *)header;
 150        unsigned int chksum = 0;
 151        while (p < header->chksum)
 152                chksum += *p++;
 153        chksum += sizeof(header->chksum) * ' ';
 154        p += sizeof(header->chksum);
 155        while (p < (char *)header + sizeof(struct ustar_header))
 156                chksum += *p++;
 157        return chksum;
 158}
 159
 160static int get_path_prefix(const struct strbuf *path, int maxlen)
 161{
 162        int i = path->len;
 163        if (i > maxlen)
 164                i = maxlen;
 165        do {
 166                i--;
 167        } while (i > 0 && path->buf[i] != '/');
 168        return i;
 169}
 170
 171static void write_entry(const unsigned char *sha1, struct strbuf *path,
 172                        unsigned int mode, void *buffer, unsigned long size)
 173{
 174        struct ustar_header header;
 175        struct strbuf ext_header;
 176
 177        memset(&header, 0, sizeof(header));
 178        ext_header.buf = NULL;
 179        ext_header.len = ext_header.alloc = 0;
 180
 181        if (!sha1) {
 182                *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 183                mode = 0100666;
 184                strcpy(header.name, "pax_global_header");
 185        } else if (!path) {
 186                *header.typeflag = TYPEFLAG_EXT_HEADER;
 187                mode = 0100666;
 188                sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 189        } else {
 190                if (S_ISDIR(mode)) {
 191                        *header.typeflag = TYPEFLAG_DIR;
 192                        mode = (mode | 0777) & ~tar_umask;
 193                } else if (S_ISLNK(mode)) {
 194                        *header.typeflag = TYPEFLAG_LNK;
 195                        mode |= 0777;
 196                } else if (S_ISREG(mode)) {
 197                        *header.typeflag = TYPEFLAG_REG;
 198                        mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 199                } else {
 200                        error("unsupported file mode: 0%o (SHA1: %s)",
 201                              mode, sha1_to_hex(sha1));
 202                        return;
 203                }
 204                if (path->len > sizeof(header.name)) {
 205                        int plen = get_path_prefix(path, sizeof(header.prefix));
 206                        int rest = path->len - plen - 1;
 207                        if (plen > 0 && rest <= sizeof(header.name)) {
 208                                memcpy(header.prefix, path->buf, plen);
 209                                memcpy(header.name, path->buf + plen + 1, rest);
 210                        } else {
 211                                sprintf(header.name, "%s.data",
 212                                        sha1_to_hex(sha1));
 213                                strbuf_append_ext_header(&ext_header, "path",
 214                                                         path->buf, path->len);
 215                        }
 216                } else
 217                        memcpy(header.name, path->buf, path->len);
 218        }
 219
 220        if (S_ISLNK(mode) && buffer) {
 221                if (size > sizeof(header.linkname)) {
 222                        sprintf(header.linkname, "see %s.paxheader",
 223                                sha1_to_hex(sha1));
 224                        strbuf_append_ext_header(&ext_header, "linkpath",
 225                                                 buffer, size);
 226                } else
 227                        memcpy(header.linkname, buffer, size);
 228        }
 229
 230        sprintf(header.mode, "%07o", mode & 07777);
 231        sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 232        sprintf(header.mtime, "%011lo", archive_time);
 233
 234        /* XXX: should we provide more meaningful info here? */
 235        sprintf(header.uid, "%07o", 0);
 236        sprintf(header.gid, "%07o", 0);
 237        strlcpy(header.uname, "git", sizeof(header.uname));
 238        strlcpy(header.gname, "git", sizeof(header.gname));
 239        sprintf(header.devmajor, "%07o", 0);
 240        sprintf(header.devminor, "%07o", 0);
 241
 242        memcpy(header.magic, "ustar", 6);
 243        memcpy(header.version, "00", 2);
 244
 245        sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 246
 247        if (ext_header.len > 0) {
 248                write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
 249                free(ext_header.buf);
 250        }
 251        write_blocked(&header, sizeof(header));
 252        if (S_ISREG(mode) && buffer && size > 0)
 253                write_blocked(buffer, size);
 254}
 255
 256static void write_global_extended_header(const unsigned char *sha1)
 257{
 258        struct strbuf ext_header;
 259        ext_header.buf = NULL;
 260        ext_header.len = ext_header.alloc = 0;
 261        strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 262        write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
 263        free(ext_header.buf);
 264}
 265
 266static void traverse_tree(struct tree_desc *tree, struct strbuf *path)
 267{
 268        int pathlen = path->len;
 269        struct name_entry entry;
 270
 271        while (tree_entry(tree, &entry)) {
 272                void *eltbuf;
 273                char elttype[20];
 274                unsigned long eltsize;
 275
 276                eltbuf = read_sha1_file(entry.sha1, elttype, &eltsize);
 277                if (!eltbuf)
 278                        die("cannot read %s", sha1_to_hex(entry.sha1));
 279
 280                path->len = pathlen;
 281                strbuf_append_string(path, entry.path);
 282                if (S_ISDIR(entry.mode))
 283                        strbuf_append_string(path, "/");
 284
 285                write_entry(entry.sha1, path, entry.mode, eltbuf, eltsize);
 286
 287                if (S_ISDIR(entry.mode)) {
 288                        struct tree_desc subtree;
 289                        subtree.buf = eltbuf;
 290                        subtree.size = eltsize;
 291                        traverse_tree(&subtree, path);
 292                }
 293                free(eltbuf);
 294        }
 295}
 296
 297int git_tar_config(const char *var, const char *value)
 298{
 299        if (!strcmp(var, "tar.umask")) {
 300                if (!strcmp(value, "user")) {
 301                        tar_umask = umask(0);
 302                        umask(tar_umask);
 303                } else {
 304                        tar_umask = git_config_int(var, value);
 305                }
 306                return 0;
 307        }
 308        return git_default_config(var, value);
 309}
 310
 311static int generate_tar(int argc, const char **argv, const char *prefix)
 312{
 313        unsigned char sha1[20], tree_sha1[20];
 314        struct commit *commit;
 315        struct tree_desc tree;
 316        struct strbuf current_path;
 317        void *buffer;
 318
 319        current_path.buf = xmalloc(PATH_MAX);
 320        current_path.alloc = PATH_MAX;
 321        current_path.len = current_path.eof = 0;
 322
 323        git_config(git_tar_config);
 324
 325        switch (argc) {
 326        case 3:
 327                strbuf_append_string(&current_path, argv[2]);
 328                strbuf_append_string(&current_path, "/");
 329                /* FALLTHROUGH */
 330        case 2:
 331                if (get_sha1(argv[1], sha1))
 332                        die("Not a valid object name %s", argv[1]);
 333                break;
 334        default:
 335                usage(tar_tree_usage);
 336        }
 337
 338        commit = lookup_commit_reference_gently(sha1, 1);
 339        if (commit) {
 340                write_global_extended_header(commit->object.sha1);
 341                archive_time = commit->date;
 342        } else
 343                archive_time = time(NULL);
 344
 345        tree.buf = buffer = read_object_with_reference(sha1, tree_type,
 346                                                       &tree.size, tree_sha1);
 347        if (!tree.buf)
 348                die("not a reference to a tag, commit or tree object: %s",
 349                    sha1_to_hex(sha1));
 350
 351        if (current_path.len > 0)
 352                write_entry(tree_sha1, &current_path, 040777, NULL, 0);
 353        traverse_tree(&tree, &current_path);
 354        write_trailer();
 355        free(buffer);
 356        free(current_path.buf);
 357        return 0;
 358}
 359
 360static const char *exec = "git-upload-tar";
 361
 362static int remote_tar(int argc, const char **argv)
 363{
 364        int fd[2], ret, len;
 365        pid_t pid;
 366        char buf[1024];
 367        char *url;
 368
 369        if (argc < 3 || 4 < argc)
 370                usage(tar_tree_usage);
 371
 372        /* --remote=<repo> */
 373        url = strdup(argv[1]+9);
 374        pid = git_connect(fd, url, exec);
 375        if (pid < 0)
 376                return 1;
 377
 378        packet_write(fd[1], "want %s\n", argv[2]);
 379        if (argv[3])
 380                packet_write(fd[1], "base %s\n", argv[3]);
 381        packet_flush(fd[1]);
 382
 383        len = packet_read_line(fd[0], buf, sizeof(buf));
 384        if (!len)
 385                die("git-tar-tree: expected ACK/NAK, got EOF");
 386        if (buf[len-1] == '\n')
 387                buf[--len] = 0;
 388        if (strcmp(buf, "ACK")) {
 389                if (5 < len && !strncmp(buf, "NACK ", 5))
 390                        die("git-tar-tree: NACK %s", buf + 5);
 391                die("git-tar-tree: protocol error");
 392        }
 393        /* expect a flush */
 394        len = packet_read_line(fd[0], buf, sizeof(buf));
 395        if (len)
 396                die("git-tar-tree: expected a flush");
 397
 398        /* Now, start reading from fd[0] and spit it out to stdout */
 399        ret = copy_fd(fd[0], 1);
 400        close(fd[0]);
 401
 402        ret |= finish_connect(pid);
 403        return !!ret;
 404}
 405
 406int cmd_tar_tree(int argc, const char **argv, const char *prefix)
 407{
 408        if (argc < 2)
 409                usage(tar_tree_usage);
 410        if (!strncmp("--remote=", argv[1], 9))
 411                return remote_tar(argc, argv);
 412        return generate_tar(argc, argv, prefix);
 413}
 414
 415/* ustar header + extended global header content */
 416#define HEADERSIZE (2 * RECORDSIZE)
 417
 418int cmd_get_tar_commit_id(int argc, const char **argv, const char *prefix)
 419{
 420        char buffer[HEADERSIZE];
 421        struct ustar_header *header = (struct ustar_header *)buffer;
 422        char *content = buffer + RECORDSIZE;
 423        ssize_t n;
 424
 425        n = xread(0, buffer, HEADERSIZE);
 426        if (n < HEADERSIZE)
 427                die("git-get-tar-commit-id: read error");
 428        if (header->typeflag[0] != 'g')
 429                return 1;
 430        if (memcmp(content, "52 comment=", 11))
 431                return 1;
 432
 433        n = xwrite(1, content + 11, 41);
 434        if (n < 41)
 435                die("git-get-tar-commit-id: write error");
 436
 437        return 0;
 438}