Andrew's git - gitweb.git/blob

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