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