Andrew's git - gitweb.git/blob

   1/*
   2 * Copyright (c) 2005, 2006 Rene Scharfe
   3 */
   4#include <time.h>
   5#include "cache.h"
   6#include "diff.h"
   7#include "commit.h"
   8#include "strbuf.h"
   9#include "tar.h"
  10
  11#define RECORDSIZE      (512)
  12#define BLOCKSIZE       (RECORDSIZE * 20)
  13
  14static const char tar_tree_usage[] = "git-tar-tree <key> [basedir]";
  15
  16static char block[BLOCKSIZE];
  17static unsigned long offset;
  18
  19static time_t archive_time;
  20
  21/* tries hard to write, either succeeds or dies in the attempt */
  22static void reliable_write(void *buf, unsigned long size)
  23{
  24        while (size > 0) {
  25                long ret = xwrite(1, buf, size);
  26                if (ret < 0) {
  27                        if (errno == EPIPE)
  28                                exit(0);
  29                        die("git-tar-tree: %s", strerror(errno));
  30                } else if (!ret) {
  31                        die("git-tar-tree: disk full?");
  32                }
  33                size -= ret;
  34                buf += ret;
  35        }
  36}
  37
  38/* writes out the whole block, but only if it is full */
  39static void write_if_needed(void)
  40{
  41        if (offset == BLOCKSIZE) {
  42                reliable_write(block, BLOCKSIZE);
  43                offset = 0;
  44        }
  45}
  46
  47/* acquire the next record from the buffer; user must call write_if_needed() */
  48static char *get_record(void)
  49{
  50        char *p = block + offset;
  51        memset(p, 0, RECORDSIZE);
  52        offset += RECORDSIZE;
  53        return p;
  54}
  55
  56/*
  57 * The end of tar archives is marked by 1024 nul bytes and after that
  58 * follows the rest of the block (if any).
  59 */
  60static void write_trailer(void)
  61{
  62        get_record();
  63        write_if_needed();
  64        get_record();
  65        write_if_needed();
  66        while (offset) {
  67                get_record();
  68                write_if_needed();
  69        }
  70}
  71
  72/*
  73 * queues up writes, so that all our write(2) calls write exactly one
  74 * full block; pads writes to RECORDSIZE
  75 */
  76static void write_blocked(void *buf, unsigned long size)
  77{
  78        unsigned long tail;
  79
  80        if (offset) {
  81                unsigned long chunk = BLOCKSIZE - offset;
  82                if (size < chunk)
  83                        chunk = size;
  84                memcpy(block + offset, buf, chunk);
  85                size -= chunk;
  86                offset += chunk;
  87                buf += chunk;
  88                write_if_needed();
  89        }
  90        while (size >= BLOCKSIZE) {
  91                reliable_write(buf, BLOCKSIZE);
  92                size -= BLOCKSIZE;
  93                buf += BLOCKSIZE;
  94        }
  95        if (size) {
  96                memcpy(block + offset, buf, size);
  97                buf += size;
  98                offset += size;
  99        }
 100        tail = offset % RECORDSIZE;
 101        if (tail)  {
 102                memset(block + offset, 0, RECORDSIZE - tail);
 103                offset += RECORDSIZE - tail;
 104        }
 105        write_if_needed();
 106}
 107
 108static void strbuf_append_string(struct strbuf *sb, const char *s)
 109{
 110        int slen = strlen(s);
 111        int total = sb->len + slen;
 112        if (total > sb->alloc) {
 113                sb->buf = xrealloc(sb->buf, total);
 114                sb->alloc = total;
 115        }
 116        memcpy(sb->buf + sb->len, s, slen);
 117        sb->len = total;
 118}
 119
 120/*
 121 * pax extended header records have the format "%u %s=%s\n".  %u contains
 122 * the size of the whole string (including the %u), the first %s is the
 123 * keyword, the second one is the value.  This function constructs such a
 124 * string and appends it to a struct strbuf.
 125 */
 126static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 127                                     const char *value, unsigned int valuelen)
 128{
 129        char *p;
 130        int len, total, tmp;
 131
 132        /* "%u %s=%s\n" */
 133        len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 134        for (tmp = len; tmp > 9; tmp /= 10)
 135                len++;
 136
 137        total = sb->len + len;
 138        if (total > sb->alloc) {
 139                sb->buf = xrealloc(sb->buf, total);
 140                sb->alloc = total;
 141        }
 142
 143        p = sb->buf;
 144        p += sprintf(p, "%u %s=", len, keyword);
 145        memcpy(p, value, valuelen);
 146        p += valuelen;
 147        *p = '\n';
 148        sb->len = total;
 149}
 150
 151static unsigned int ustar_header_chksum(const struct ustar_header *header)
 152{
 153        char *p = (char *)header;
 154        unsigned int chksum = 0;
 155        while (p < header->chksum)
 156                chksum += *p++;
 157        chksum += sizeof(header->chksum) * ' ';
 158        p += sizeof(header->chksum);
 159        while (p < (char *)header + sizeof(struct ustar_header))
 160                chksum += *p++;
 161        return chksum;
 162}
 163
 164static int get_path_prefix(const struct strbuf *path, int maxlen)
 165{
 166        int i = path->len;
 167        if (i > maxlen)
 168                i = maxlen;
 169        while (i > 0 && path->buf[i] != '/')
 170                i--;
 171        return i;
 172}
 173
 174static void write_entry(const unsigned char *sha1, struct strbuf *path,
 175                        unsigned int mode, void *buffer, unsigned long size)
 176{
 177        struct ustar_header header;
 178        struct strbuf ext_header;
 179
 180        memset(&header, 0, sizeof(header));
 181        ext_header.buf = NULL;
 182        ext_header.len = ext_header.alloc = 0;
 183
 184        if (!sha1) {
 185                *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 186                mode = 0100666;
 187                strcpy(header.name, "pax_global_header");
 188        } else if (!path) {
 189                *header.typeflag = TYPEFLAG_EXT_HEADER;
 190                mode = 0100666;
 191                sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 192        } else {
 193                if (S_ISDIR(mode)) {
 194                        *header.typeflag = TYPEFLAG_DIR;
 195                        mode |= 0777;
 196                } else if (S_ISLNK(mode)) {
 197                        *header.typeflag = TYPEFLAG_LNK;
 198                        mode |= 0777;
 199                } else if (S_ISREG(mode)) {
 200                        *header.typeflag = TYPEFLAG_REG;
 201                        mode |= (mode & 0100) ? 0777 : 0666;
 202                } else {
 203                        error("unsupported file mode: 0%o (SHA1: %s)",
 204                              mode, sha1_to_hex(sha1));
 205                        return;
 206                }
 207                if (path->len > sizeof(header.name)) {
 208                        int plen = get_path_prefix(path, sizeof(header.prefix));
 209                        int rest = path->len - plen - 1;
 210                        if (plen > 0 && rest <= sizeof(header.name)) {
 211                                memcpy(header.prefix, path->buf, plen);
 212                                memcpy(header.name, path->buf + plen + 1, rest);
 213                        } else {
 214                                sprintf(header.name, "%s.data",
 215                                        sha1_to_hex(sha1));
 216                                strbuf_append_ext_header(&ext_header, "path",
 217                                                         path->buf, path->len);
 218                        }
 219                } else
 220                        memcpy(header.name, path->buf, path->len);
 221        }
 222
 223        if (S_ISLNK(mode) && buffer) {
 224                if (size > sizeof(header.linkname)) {
 225                        sprintf(header.linkname, "see %s.paxheader",
 226                                sha1_to_hex(sha1));
 227                        strbuf_append_ext_header(&ext_header, "linkpath",
 228                                                 buffer, size);
 229                } else
 230                        memcpy(header.linkname, buffer, size);
 231        }
 232
 233        sprintf(header.mode, "%07o", mode & 07777);
 234        sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 235        sprintf(header.mtime, "%011lo", archive_time);
 236
 237        /* XXX: should we provide more meaningful info here? */
 238        sprintf(header.uid, "%07o", 0);
 239        sprintf(header.gid, "%07o", 0);
 240        strncpy(header.uname, "git", 31);
 241        strncpy(header.gname, "git", 31);
 242        sprintf(header.devmajor, "%07o", 0);
 243        sprintf(header.devminor, "%07o", 0);
 244
 245        memcpy(header.magic, "ustar", 6);
 246        memcpy(header.version, "00", 2);
 247
 248        sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 249
 250        if (ext_header.len > 0) {
 251                write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
 252                free(ext_header.buf);
 253        }
 254        write_blocked(&header, sizeof(header));
 255        if (S_ISREG(mode) && buffer && size > 0)
 256                write_blocked(buffer, size);
 257}
 258
 259static void write_global_extended_header(const unsigned char *sha1)
 260{
 261        struct strbuf ext_header;
 262        ext_header.buf = NULL;
 263        ext_header.len = ext_header.alloc = 0;
 264        strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 265        write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
 266        free(ext_header.buf);
 267}
 268
 269static void traverse_tree(struct tree_desc *tree, struct strbuf *path)
 270{
 271        int pathlen = path->len;
 272
 273        while (tree->size) {
 274                const char *name;
 275                const unsigned char *sha1;
 276                unsigned mode;
 277                void *eltbuf;
 278                char elttype[20];
 279                unsigned long eltsize;
 280
 281                sha1 = tree_entry_extract(tree, &name, &mode);
 282                update_tree_entry(tree);
 283
 284                eltbuf = read_sha1_file(sha1, elttype, &eltsize);
 285                if (!eltbuf)
 286                        die("cannot read %s", sha1_to_hex(sha1));
 287
 288                path->len = pathlen;
 289                strbuf_append_string(path, name);
 290                if (S_ISDIR(mode))
 291                        strbuf_append_string(path, "/");
 292
 293                write_entry(sha1, path, mode, eltbuf, eltsize);
 294
 295                if (S_ISDIR(mode)) {
 296                        struct tree_desc subtree;
 297                        subtree.buf = eltbuf;
 298                        subtree.size = eltsize;
 299                        traverse_tree(&subtree, path);
 300                }
 301                free(eltbuf);
 302        }
 303}
 304
 305int main(int argc, char **argv)
 306{
 307        unsigned char sha1[20], tree_sha1[20];
 308        struct commit *commit;
 309        struct tree_desc tree;
 310        struct strbuf current_path;
 311
 312        current_path.buf = xmalloc(PATH_MAX);
 313        current_path.alloc = PATH_MAX;
 314        current_path.len = current_path.eof = 0;
 315
 316        setup_git_directory();
 317        git_config(git_default_config);
 318
 319        switch (argc) {
 320        case 3:
 321                strbuf_append_string(&current_path, argv[2]);
 322                strbuf_append_string(&current_path, "/");
 323                /* FALLTHROUGH */
 324        case 2:
 325                if (get_sha1(argv[1], sha1) < 0)
 326                        usage(tar_tree_usage);
 327                break;
 328        default:
 329                usage(tar_tree_usage);
 330        }
 331
 332        commit = lookup_commit_reference_gently(sha1, 1);
 333        if (commit) {
 334                write_global_extended_header(commit->object.sha1);
 335                archive_time = commit->date;
 336        } else
 337                archive_time = time(NULL);
 338
 339        tree.buf = read_object_with_reference(sha1, "tree", &tree.size,
 340                                              tree_sha1);
 341        if (!tree.buf)
 342                die("not a reference to a tag, commit or tree object: %s",
 343                    sha1_to_hex(sha1));
 344
 345        if (current_path.len > 0)
 346                write_entry(tree_sha1, &current_path, 040777, NULL, 0);
 347        traverse_tree(&tree, &current_path);
 348        write_trailer();
 349        free(current_path.buf);
 350        return 0;
 351}