archive-tar.c

   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
  13 static char block[BLOCKSIZE];
  14 static unsigned long offset;
  15
  16 static time_t archive_time;
  17 static int tar_umask = 002;
  18 static int verbose;
  19 static const struct commit *commit;
  20 static size_t base_len;
  21
  22 /* writes out the whole block, but only if it is full */
  23 static void write_if_needed(void)
  24 {
  25         if (offset == BLOCKSIZE) {
  26                 write_or_die(1, block, BLOCKSIZE);
  27                 offset = 0;
  28         }
  29 }
  30
  31 /*
  32  * queues up writes, so that all our write(2) calls write exactly one
  33  * full block; pads writes to RECORDSIZE
  34  */
  35 static void write_blocked(const void *data, unsigned long size)
  36 {
  37         const char *buf = data;
  38         unsigned long tail;
  39
  40         if (offset) {
  41                 unsigned long chunk = BLOCKSIZE - offset;
  42                 if (size < chunk)
  43                         chunk = size;
  44                 memcpy(block + offset, buf, chunk);
  45                 size -= chunk;
  46                 offset += chunk;
  47                 buf += chunk;
  48                 write_if_needed();
  49         }
  50         while (size >= BLOCKSIZE) {
  51                 write_or_die(1, buf, BLOCKSIZE);
  52                 size -= BLOCKSIZE;
  53                 buf += BLOCKSIZE;
  54         }
  55         if (size) {
  56                 memcpy(block + offset, buf, size);
  57                 offset += size;
  58         }
  59         tail = offset % RECORDSIZE;
  60         if (tail)  {
  61                 memset(block + offset, 0, RECORDSIZE - tail);
  62                 offset += RECORDSIZE - tail;
  63         }
  64         write_if_needed();
  65 }
  66
  67 /*
  68  * The end of tar archives is marked by 2*512 nul bytes and after that
  69  * follows the rest of the block (if any).
  70  */
  71 static void write_trailer(void)
  72 {
  73         int tail = BLOCKSIZE - offset;
  74         memset(block + offset, 0, tail);
  75         write_or_die(1, block, BLOCKSIZE);
  76         if (tail < 2 * RECORDSIZE) {
  77                 memset(block, 0, offset);
  78                 write_or_die(1, block, BLOCKSIZE);
  79         }
  80 }
  81
  82 /*
  83  * pax extended header records have the format "%u %s=%s\n".  %u contains
  84  * the size of the whole string (including the %u), the first %s is the
  85  * keyword, the second one is the value.  This function constructs such a
  86  * string and appends it to a struct strbuf.
  87  */
  88 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
  89                                      const char *value, unsigned int valuelen)
  90 {
  91         int len, tmp;
  92
  93         /* "%u %s=%s\n" */
  94         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
  95         for (tmp = len; tmp > 9; tmp /= 10)
  96                 len++;
  97
  98         strbuf_grow(sb, len);
  99         strbuf_addf(sb, "%u %s=", len, keyword);
 100         strbuf_add(sb, value, valuelen);
 101         strbuf_addch(sb, '\n');
 102 }
 103
 104 static unsigned int ustar_header_chksum(const struct ustar_header *header)
 105 {
 106         char *p = (char *)header;
 107         unsigned int chksum = 0;
 108         while (p < header->chksum)
 109                 chksum += *p++;
 110         chksum += sizeof(header->chksum) * ' ';
 111         p += sizeof(header->chksum);
 112         while (p < (char *)header + sizeof(struct ustar_header))
 113                 chksum += *p++;
 114         return chksum;
 115 }
 116
 117 static int get_path_prefix(const struct strbuf *path, int maxlen)
 118 {
 119         int i = path->len;
 120         if (i > maxlen)
 121                 i = maxlen;
 122         do {
 123                 i--;
 124         } while (i > 0 && path->buf[i] != '/');
 125         return i;
 126 }
 127
 128 static void write_entry(const unsigned char *sha1, struct strbuf *path,
 129                         unsigned int mode, void *buffer, unsigned long size)
 130 {
 131         struct ustar_header header;
 132         struct strbuf ext_header;
 133
 134         memset(&header, 0, sizeof(header));
 135         strbuf_init(&ext_header, 0);
 136
 137         if (!sha1) {
 138                 *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 139                 mode = 0100666;
 140                 strcpy(header.name, "pax_global_header");
 141         } else if (!path) {
 142                 *header.typeflag = TYPEFLAG_EXT_HEADER;
 143                 mode = 0100666;
 144                 sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 145         } else {
 146                 if (verbose)
 147                         fprintf(stderr, "%.*s\n", (int)path->len, path->buf);
 148                 if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 149                         *header.typeflag = TYPEFLAG_DIR;
 150                         mode = (mode | 0777) & ~tar_umask;
 151                 } else if (S_ISLNK(mode)) {
 152                         *header.typeflag = TYPEFLAG_LNK;
 153                         mode |= 0777;
 154                 } else if (S_ISREG(mode)) {
 155                         *header.typeflag = TYPEFLAG_REG;
 156                         mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 157                 } else {
 158                         error("unsupported file mode: 0%o (SHA1: %s)",
 159                               mode, sha1_to_hex(sha1));
 160                         return;
 161                 }
 162                 if (path->len > sizeof(header.name)) {
 163                         int plen = get_path_prefix(path, sizeof(header.prefix));
 164                         int rest = path->len - plen - 1;
 165                         if (plen > 0 && rest <= sizeof(header.name)) {
 166                                 memcpy(header.prefix, path->buf, plen);
 167                                 memcpy(header.name, path->buf + plen + 1, rest);
 168                         } else {
 169                                 sprintf(header.name, "%s.data",
 170                                         sha1_to_hex(sha1));
 171                                 strbuf_append_ext_header(&ext_header, "path",
 172                                                          path->buf, path->len);
 173                         }
 174                 } else
 175                         memcpy(header.name, path->buf, path->len);
 176         }
 177
 178         if (S_ISLNK(mode) && buffer) {
 179                 if (size > sizeof(header.linkname)) {
 180                         sprintf(header.linkname, "see %s.paxheader",
 181                                 sha1_to_hex(sha1));
 182                         strbuf_append_ext_header(&ext_header, "linkpath",
 183                                                  buffer, size);
 184                 } else
 185                         memcpy(header.linkname, buffer, size);
 186         }
 187
 188         sprintf(header.mode, "%07o", mode & 07777);
 189         sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 190         sprintf(header.mtime, "%011lo", archive_time);
 191
 192         sprintf(header.uid, "%07o", 0);
 193         sprintf(header.gid, "%07o", 0);
 194         strlcpy(header.uname, "root", sizeof(header.uname));
 195         strlcpy(header.gname, "root", sizeof(header.gname));
 196         sprintf(header.devmajor, "%07o", 0);
 197         sprintf(header.devminor, "%07o", 0);
 198
 199         memcpy(header.magic, "ustar", 6);
 200         memcpy(header.version, "00", 2);
 201
 202         sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 203
 204         if (ext_header.len > 0) {
 205                 write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
 206         }
 207         strbuf_release(&ext_header);
 208         write_blocked(&header, sizeof(header));
 209         if (S_ISREG(mode) && buffer && size > 0)
 210                 write_blocked(buffer, size);
 211 }
 212
 213 static void write_global_extended_header(const unsigned char *sha1)
 214 {
 215         struct strbuf ext_header;
 216
 217         strbuf_init(&ext_header, 0);
 218         strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 219         write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
 220         strbuf_release(&ext_header);
 221 }
 222
 223 static 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
 237 static int write_tar_entry(const unsigned char *sha1,
 238                            const char *base, int baselen,
 239                            const char *filename, unsigned mode, int stage)
 240 {
 241         static struct strbuf path = STRBUF_INIT;
 242         void *buffer;
 243         enum object_type type;
 244         unsigned long size;
 245
 246         strbuf_reset(&path);
 247         strbuf_grow(&path, PATH_MAX);
 248         strbuf_add(&path, base, baselen);
 249         strbuf_addstr(&path, filename);
 250         if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 251                 strbuf_addch(&path, '/');
 252                 buffer = NULL;
 253                 size = 0;
 254         } else {
 255                 buffer = sha1_file_to_archive(path.buf + base_len, sha1, mode,
 256                                 &type, &size, commit);
 257                 if (!buffer)
 258                         die("cannot read %s", sha1_to_hex(sha1));
 259         }
 260
 261         write_entry(sha1, &path, mode, buffer, size);
 262         free(buffer);
 263
 264         return READ_TREE_RECURSIVE;
 265 }
 266
 267 int write_tar_archive(struct archiver_args *args)
 268 {
 269         int plen = args->base ? strlen(args->base) : 0;
 270
 271         git_config(git_tar_config, NULL);
 272
 273         archive_time = args->time;
 274         verbose = args->verbose;
 275         commit = args->commit;
 276         base_len = args->base ? strlen(args->base) : 0;
 277
 278         if (args->commit_sha1)
 279                 write_global_extended_header(args->commit_sha1);
 280
 281         if (args->base && plen > 0 && args->base[plen - 1] == '/') {
 282                 char *base = xstrdup(args->base);
 283                 int baselen = strlen(base);
 284
 285                 while (baselen > 0 && base[baselen - 1] == '/')
 286                         base[--baselen] = '\0';
 287                 write_tar_entry(args->tree->object.sha1, "", 0, base, 040777, 0);
 288                 free(base);
 289         }
 290         read_tree_recursive(args->tree, args->base, plen, 0,
 291                             args->pathspec, write_tar_entry);
 292         write_trailer();
 293
 294         return 0;
 295 }