Andrew's git - gitweb.git/blob

   1/*
   2 * Copyright (c) 2005, 2006 Rene Scharfe
   3 */
   4#include "cache.h"
   5#include "commit.h"
   6#include "tar.h"
   7#include "builtin.h"
   8#include "archive.h"
   9
  10#define RECORDSIZE      (512)
  11#define BLOCKSIZE       (RECORDSIZE * 20)
  12
  13static char block[BLOCKSIZE];
  14static unsigned long offset;
  15
  16static int tar_umask = 002;
  17
  18/* writes out the whole block, but only if it is full */
  19static void write_if_needed(void)
  20{
  21        if (offset == BLOCKSIZE) {
  22                write_or_die(1, block, BLOCKSIZE);
  23                offset = 0;
  24        }
  25}
  26
  27/*
  28 * queues up writes, so that all our write(2) calls write exactly one
  29 * full block; pads writes to RECORDSIZE
  30 */
  31static void write_blocked(const void *data, unsigned long size)
  32{
  33        const char *buf = data;
  34        unsigned long tail;
  35
  36        if (offset) {
  37                unsigned long chunk = BLOCKSIZE - offset;
  38                if (size < chunk)
  39                        chunk = size;
  40                memcpy(block + offset, buf, chunk);
  41                size -= chunk;
  42                offset += chunk;
  43                buf += chunk;
  44                write_if_needed();
  45        }
  46        while (size >= BLOCKSIZE) {
  47                write_or_die(1, buf, BLOCKSIZE);
  48                size -= BLOCKSIZE;
  49                buf += BLOCKSIZE;
  50        }
  51        if (size) {
  52                memcpy(block + offset, buf, size);
  53                offset += size;
  54        }
  55        tail = offset % RECORDSIZE;
  56        if (tail)  {
  57                memset(block + offset, 0, RECORDSIZE - tail);
  58                offset += RECORDSIZE - tail;
  59        }
  60        write_if_needed();
  61}
  62
  63/*
  64 * The end of tar archives is marked by 2*512 nul bytes and after that
  65 * follows the rest of the block (if any).
  66 */
  67static void write_trailer(void)
  68{
  69        int tail = BLOCKSIZE - offset;
  70        memset(block + offset, 0, tail);
  71        write_or_die(1, block, BLOCKSIZE);
  72        if (tail < 2 * RECORDSIZE) {
  73                memset(block, 0, offset);
  74                write_or_die(1, block, BLOCKSIZE);
  75        }
  76}
  77
  78/*
  79 * pax extended header records have the format "%u %s=%s\n".  %u contains
  80 * the size of the whole string (including the %u), the first %s is the
  81 * keyword, the second one is the value.  This function constructs such a
  82 * string and appends it to a struct strbuf.
  83 */
  84static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
  85                                     const char *value, unsigned int valuelen)
  86{
  87        int len, tmp;
  88
  89        /* "%u %s=%s\n" */
  90        len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
  91        for (tmp = len; tmp > 9; tmp /= 10)
  92                len++;
  93
  94        strbuf_grow(sb, len);
  95        strbuf_addf(sb, "%u %s=", len, keyword);
  96        strbuf_add(sb, value, valuelen);
  97        strbuf_addch(sb, '\n');
  98}
  99
 100static unsigned int ustar_header_chksum(const struct ustar_header *header)
 101{
 102        char *p = (char *)header;
 103        unsigned int chksum = 0;
 104        while (p < header->chksum)
 105                chksum += *p++;
 106        chksum += sizeof(header->chksum) * ' ';
 107        p += sizeof(header->chksum);
 108        while (p < (char *)header + sizeof(struct ustar_header))
 109                chksum += *p++;
 110        return chksum;
 111}
 112
 113static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
 114{
 115        size_t i = pathlen;
 116        if (i > maxlen)
 117                i = maxlen;
 118        do {
 119                i--;
 120        } while (i > 0 && path[i] != '/');
 121        return i;
 122}
 123
 124static int write_tar_entry(struct archiver_args *args,
 125                const unsigned char *sha1, const char *path, size_t pathlen,
 126                unsigned int mode, void *buffer, unsigned long size)
 127{
 128        struct ustar_header header;
 129        struct strbuf ext_header;
 130        int err = 0;
 131
 132        memset(&header, 0, sizeof(header));
 133        strbuf_init(&ext_header, 0);
 134
 135        if (!sha1) {
 136                *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 137                mode = 0100666;
 138                strcpy(header.name, "pax_global_header");
 139        } else if (!path) {
 140                *header.typeflag = TYPEFLAG_EXT_HEADER;
 141                mode = 0100666;
 142                sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 143        } else {
 144                if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 145                        *header.typeflag = TYPEFLAG_DIR;
 146                        mode = (mode | 0777) & ~tar_umask;
 147                } else if (S_ISLNK(mode)) {
 148                        *header.typeflag = TYPEFLAG_LNK;
 149                        mode |= 0777;
 150                } else if (S_ISREG(mode)) {
 151                        *header.typeflag = TYPEFLAG_REG;
 152                        mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 153                } else {
 154                        return error("unsupported file mode: 0%o (SHA1: %s)",
 155                                        mode, sha1_to_hex(sha1));
 156                }
 157                if (pathlen > sizeof(header.name)) {
 158                        size_t plen = get_path_prefix(path, pathlen,
 159                                        sizeof(header.prefix));
 160                        size_t rest = pathlen - plen - 1;
 161                        if (plen > 0 && rest <= sizeof(header.name)) {
 162                                memcpy(header.prefix, path, plen);
 163                                memcpy(header.name, path + plen + 1, rest);
 164                        } else {
 165                                sprintf(header.name, "%s.data",
 166                                        sha1_to_hex(sha1));
 167                                strbuf_append_ext_header(&ext_header, "path",
 168                                                path, pathlen);
 169                        }
 170                } else
 171                        memcpy(header.name, path, pathlen);
 172        }
 173
 174        if (S_ISLNK(mode) && buffer) {
 175                if (size > sizeof(header.linkname)) {
 176                        sprintf(header.linkname, "see %s.paxheader",
 177                                sha1_to_hex(sha1));
 178                        strbuf_append_ext_header(&ext_header, "linkpath",
 179                                                 buffer, size);
 180                } else
 181                        memcpy(header.linkname, buffer, size);
 182        }
 183
 184        sprintf(header.mode, "%07o", mode & 07777);
 185        sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 186        sprintf(header.mtime, "%011lo", args->time);
 187
 188        sprintf(header.uid, "%07o", 0);
 189        sprintf(header.gid, "%07o", 0);
 190        strlcpy(header.uname, "root", sizeof(header.uname));
 191        strlcpy(header.gname, "root", sizeof(header.gname));
 192        sprintf(header.devmajor, "%07o", 0);
 193        sprintf(header.devminor, "%07o", 0);
 194
 195        memcpy(header.magic, "ustar", 6);
 196        memcpy(header.version, "00", 2);
 197
 198        sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 199
 200        if (ext_header.len > 0) {
 201                err = write_tar_entry(args, sha1, NULL, 0, 0, ext_header.buf,
 202                                ext_header.len);
 203                if (err)
 204                        return err;
 205        }
 206        strbuf_release(&ext_header);
 207        write_blocked(&header, sizeof(header));
 208        if (S_ISREG(mode) && buffer && size > 0)
 209                write_blocked(buffer, size);
 210        return err;
 211}
 212
 213static int write_global_extended_header(struct archiver_args *args)
 214{
 215        const unsigned char *sha1 = args->commit_sha1;
 216        struct strbuf ext_header;
 217        int err;
 218
 219        strbuf_init(&ext_header, 0);
 220        strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 221        err = write_tar_entry(args, NULL, NULL, 0, 0, ext_header.buf,
 222                        ext_header.len);
 223        strbuf_release(&ext_header);
 224        return err;
 225}
 226
 227static int git_tar_config(const char *var, const char *value, void *cb)
 228{
 229        if (!strcmp(var, "tar.umask")) {
 230                if (value && !strcmp(value, "user")) {
 231                        tar_umask = umask(0);
 232                        umask(tar_umask);
 233                } else {
 234                        tar_umask = git_config_int(var, value);
 235                }
 236                return 0;
 237        }
 238        return git_default_config(var, value, cb);
 239}
 240
 241int write_tar_archive(struct archiver_args *args)
 242{
 243        int err = 0;
 244
 245        git_config(git_tar_config, NULL);
 246
 247        if (args->commit_sha1)
 248                err = write_global_extended_header(args);
 249        if (!err)
 250                err = write_archive_entries(args, write_tar_entry);
 251        if (!err)
 252                write_trailer();
 253        return err;
 254}