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 "tree-walk.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                offset += size;
  98        }
  99        tail = offset % RECORDSIZE;
 100        if (tail)  {
 101                memset(block + offset, 0, RECORDSIZE - tail);
 102                offset += RECORDSIZE - tail;
 103        }
 104        write_if_needed();
 105}
 106
 107static void strbuf_append_string(struct strbuf *sb, const char *s)
 108{
 109        int slen = strlen(s);
 110        int total = sb->len + slen;
 111        if (total > sb->alloc) {
 112                sb->buf = xrealloc(sb->buf, total);
 113                sb->alloc = total;
 114        }
 115        memcpy(sb->buf + sb->len, s, slen);
 116        sb->len = total;
 117}
 118
 119/*
 120 * pax extended header records have the format "%u %s=%s\n".  %u contains
 121 * the size of the whole string (including the %u), the first %s is the
 122 * keyword, the second one is the value.  This function constructs such a
 123 * string and appends it to a struct strbuf.
 124 */
 125static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 126                                     const char *value, unsigned int valuelen)
 127{
 128        char *p;
 129        int len, total, tmp;
 130
 131        /* "%u %s=%s\n" */
 132        len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 133        for (tmp = len; tmp > 9; tmp /= 10)
 134                len++;
 135
 136        total = sb->len + len;
 137        if (total > sb->alloc) {
 138                sb->buf = xrealloc(sb->buf, total);
 139                sb->alloc = total;
 140        }
 141
 142        p = sb->buf;
 143        p += sprintf(p, "%u %s=", len, keyword);
 144        memcpy(p, value, valuelen);
 145        p += valuelen;
 146        *p = '\n';
 147        sb->len = total;
 148}
 149
 150static unsigned int ustar_header_chksum(const struct ustar_header *header)
 151{
 152        char *p = (char *)header;
 153        unsigned int chksum = 0;
 154        while (p < header->chksum)
 155                chksum += *p++;
 156        chksum += sizeof(header->chksum) * ' ';
 157        p += sizeof(header->chksum);
 158        while (p < (char *)header + sizeof(struct ustar_header))
 159                chksum += *p++;
 160        return chksum;
 161}
 162
 163static int get_path_prefix(const struct strbuf *path, int maxlen)
 164{
 165        int i = path->len;
 166        if (i > maxlen)
 167                i = maxlen;
 168        while (i > 0 && path->buf[i] != '/')
 169                i--;
 170        return i;
 171}
 172
 173static void write_entry(const unsigned char *sha1, struct strbuf *path,
 174                        unsigned int mode, void *buffer, unsigned long size)
 175{
 176        struct ustar_header header;
 177        struct strbuf ext_header;
 178
 179        memset(&header, 0, sizeof(header));
 180        ext_header.buf = NULL;
 181        ext_header.len = ext_header.alloc = 0;
 182
 183        if (!sha1) {
 184                *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 185                mode = 0100666;
 186                strcpy(header.name, "pax_global_header");
 187        } else if (!path) {
 188                *header.typeflag = TYPEFLAG_EXT_HEADER;
 189                mode = 0100666;
 190                sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 191        } else {
 192                if (S_ISDIR(mode)) {
 193                        *header.typeflag = TYPEFLAG_DIR;
 194                        mode |= 0777;
 195                } else if (S_ISLNK(mode)) {
 196                        *header.typeflag = TYPEFLAG_LNK;
 197                        mode |= 0777;
 198                } else if (S_ISREG(mode)) {
 199                        *header.typeflag = TYPEFLAG_REG;
 200                        mode |= (mode & 0100) ? 0777 : 0666;
 201                } else {
 202                        error("unsupported file mode: 0%o (SHA1: %s)",
 203                              mode, sha1_to_hex(sha1));
 204                        return;
 205                }
 206                if (path->len > sizeof(header.name)) {
 207                        int plen = get_path_prefix(path, sizeof(header.prefix));
 208                        int rest = path->len - plen - 1;
 209                        if (plen > 0 && rest <= sizeof(header.name)) {
 210                                memcpy(header.prefix, path->buf, plen);
 211                                memcpy(header.name, path->buf + plen + 1, rest);
 212                        } else {
 213                                sprintf(header.name, "%s.data",
 214                                        sha1_to_hex(sha1));
 215                                strbuf_append_ext_header(&ext_header, "path",
 216                                                         path->buf, path->len);
 217                        }
 218                } else
 219                        memcpy(header.name, path->buf, path->len);
 220        }
 221
 222        if (S_ISLNK(mode) && buffer) {
 223                if (size > sizeof(header.linkname)) {
 224                        sprintf(header.linkname, "see %s.paxheader",
 225                                sha1_to_hex(sha1));
 226                        strbuf_append_ext_header(&ext_header, "linkpath",
 227                                                 buffer, size);
 228                } else
 229                        memcpy(header.linkname, buffer, size);
 230        }
 231
 232        sprintf(header.mode, "%07o", mode & 07777);
 233        sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 234        sprintf(header.mtime, "%011lo", archive_time);
 235
 236        /* XXX: should we provide more meaningful info here? */
 237        sprintf(header.uid, "%07o", 0);
 238        sprintf(header.gid, "%07o", 0);
 239        strncpy(header.uname, "git", 31);
 240        strncpy(header.gname, "git", 31);
 241        sprintf(header.devmajor, "%07o", 0);
 242        sprintf(header.devminor, "%07o", 0);
 243
 244        memcpy(header.magic, "ustar", 6);
 245        memcpy(header.version, "00", 2);
 246
 247        sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 248
 249        if (ext_header.len > 0) {
 250                write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
 251                free(ext_header.buf);
 252        }
 253        write_blocked(&header, sizeof(header));
 254        if (S_ISREG(mode) && buffer && size > 0)
 255                write_blocked(buffer, size);
 256}
 257
 258static void write_global_extended_header(const unsigned char *sha1)
 259{
 260        struct strbuf ext_header;
 261        ext_header.buf = NULL;
 262        ext_header.len = ext_header.alloc = 0;
 263        strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 264        write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
 265        free(ext_header.buf);
 266}
 267
 268static void traverse_tree(struct tree_desc *tree, struct strbuf *path)
 269{
 270        int pathlen = path->len;
 271
 272        while (tree->size) {
 273                const char *name;
 274                const unsigned char *sha1;
 275                unsigned mode;
 276                void *eltbuf;
 277                char elttype[20];
 278                unsigned long eltsize;
 279
 280                sha1 = tree_entry_extract(tree, &name, &mode);
 281                update_tree_entry(tree);
 282
 283                eltbuf = read_sha1_file(sha1, elttype, &eltsize);
 284                if (!eltbuf)
 285                        die("cannot read %s", sha1_to_hex(sha1));
 286
 287                path->len = pathlen;
 288                strbuf_append_string(path, name);
 289                if (S_ISDIR(mode))
 290                        strbuf_append_string(path, "/");
 291
 292                write_entry(sha1, path, mode, eltbuf, eltsize);
 293
 294                if (S_ISDIR(mode)) {
 295                        struct tree_desc subtree;
 296                        subtree.buf = eltbuf;
 297                        subtree.size = eltsize;
 298                        traverse_tree(&subtree, path);
 299                }
 300                free(eltbuf);
 301        }
 302}
 303
 304int main(int argc, char **argv)
 305{
 306        unsigned char sha1[20], tree_sha1[20];
 307        struct commit *commit;
 308        struct tree_desc tree;
 309        struct strbuf current_path;
 310
 311        current_path.buf = xmalloc(PATH_MAX);
 312        current_path.alloc = PATH_MAX;
 313        current_path.len = current_path.eof = 0;
 314
 315        setup_git_directory();
 316        git_config(git_default_config);
 317
 318        switch (argc) {
 319        case 3:
 320                strbuf_append_string(&current_path, argv[2]);
 321                strbuf_append_string(&current_path, "/");
 322                /* FALLTHROUGH */
 323        case 2:
 324                if (get_sha1(argv[1], sha1))
 325                        die("Not a valid object name %s", argv[1]);
 326                break;
 327        default:
 328                usage(tar_tree_usage);
 329        }
 330
 331        commit = lookup_commit_reference_gently(sha1, 1);
 332        if (commit) {
 333                write_global_extended_header(commit->object.sha1);
 334                archive_time = commit->date;
 335        } else
 336                archive_time = time(NULL);
 337
 338        tree.buf = read_object_with_reference(sha1, tree_type, &tree.size,
 339                                              tree_sha1);
 340        if (!tree.buf)
 341                die("not a reference to a tag, commit or tree object: %s",
 342                    sha1_to_hex(sha1));
 343
 344        if (current_path.len > 0)
 345                write_entry(tree_sha1, &current_path, 040777, NULL, 0);
 346        traverse_tree(&tree, &current_path);
 347        write_trailer();
 348        free(current_path.buf);
 349        return 0;
 350}