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
  21 /* writes out the whole block, but only if it is full */
  22 static void write_if_needed(void)
  23 {
  24         if (offset == BLOCKSIZE) {
  25                 write_or_die(1, block, BLOCKSIZE);
  26                 offset = 0;
  27         }
  28 }
  29
  30 /*
  31  * queues up writes, so that all our write(2) calls write exactly one
  32  * full block; pads writes to RECORDSIZE
  33  */
  34 static void write_blocked(const void *data, unsigned long size)
  35 {
  36         const char *buf = data;
  37         unsigned long tail;
  38
  39         if (offset) {
  40                 unsigned long chunk = BLOCKSIZE - offset;
  41                 if (size < chunk)
  42                         chunk = size;
  43                 memcpy(block + offset, buf, chunk);
  44                 size -= chunk;
  45                 offset += chunk;
  46                 buf += chunk;
  47                 write_if_needed();
  48         }
  49         while (size >= BLOCKSIZE) {
  50                 write_or_die(1, buf, BLOCKSIZE);
  51                 size -= BLOCKSIZE;
  52                 buf += BLOCKSIZE;
  53         }
  54         if (size) {
  55                 memcpy(block + offset, buf, size);
  56                 offset += size;
  57         }
  58         tail = offset % RECORDSIZE;
  59         if (tail)  {
  60                 memset(block + offset, 0, RECORDSIZE - tail);
  61                 offset += RECORDSIZE - tail;
  62         }
  63         write_if_needed();
  64 }
  65
  66 /*
  67  * The end of tar archives is marked by 2*512 nul bytes and after that
  68  * follows the rest of the block (if any).
  69  */
  70 static void write_trailer(void)
  71 {
  72         int tail = BLOCKSIZE - offset;
  73         memset(block + offset, 0, tail);
  74         write_or_die(1, block, BLOCKSIZE);
  75         if (tail < 2 * RECORDSIZE) {
  76                 memset(block, 0, offset);
  77                 write_or_die(1, block, BLOCKSIZE);
  78         }
  79 }
  80
  81 /*
  82  * pax extended header records have the format "%u %s=%s\n".  %u contains
  83  * the size of the whole string (including the %u), the first %s is the
  84  * keyword, the second one is the value.  This function constructs such a
  85  * string and appends it to a struct strbuf.
  86  */
  87 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
  88                                      const char *value, unsigned int valuelen)
  89 {
  90         int len, tmp;
  91
  92         /* "%u %s=%s\n" */
  93         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
  94         for (tmp = len; tmp > 9; tmp /= 10)
  95                 len++;
  96
  97         strbuf_grow(sb, len);
  98         strbuf_addf(sb, "%u %s=", len, keyword);
  99         strbuf_add(sb, value, valuelen);
 100         strbuf_addch(sb, '\n');
 101 }
 102
 103 static unsigned int ustar_header_chksum(const struct ustar_header *header)
 104 {
 105         char *p = (char *)header;
 106         unsigned int chksum = 0;
 107         while (p < header->chksum)
 108                 chksum += *p++;
 109         chksum += sizeof(header->chksum) * ' ';
 110         p += sizeof(header->chksum);
 111         while (p < (char *)header + sizeof(struct ustar_header))
 112                 chksum += *p++;
 113         return chksum;
 114 }
 115
 116 static int get_path_prefix(const struct strbuf *path, int maxlen)
 117 {
 118         int i = path->len;
 119         if (i > maxlen)
 120                 i = maxlen;
 121         do {
 122                 i--;
 123         } while (i > 0 && path->buf[i] != '/');
 124         return i;
 125 }
 126
 127 static void write_entry(const unsigned char *sha1, struct strbuf *path,
 128                         unsigned int mode, void *buffer, unsigned long size)
 129 {
 130         struct ustar_header header;
 131         struct strbuf ext_header;
 132
 133         memset(&header, 0, sizeof(header));
 134         strbuf_init(&ext_header, 0);
 135
 136         if (!sha1) {
 137                 *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 138                 mode = 0100666;
 139                 strcpy(header.name, "pax_global_header");
 140         } else if (!path) {
 141                 *header.typeflag = TYPEFLAG_EXT_HEADER;
 142                 mode = 0100666;
 143                 sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 144         } else {
 145                 if (verbose)
 146                         fprintf(stderr, "%.*s\n", (int)path->len, path->buf);
 147                 if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 148                         *header.typeflag = TYPEFLAG_DIR;
 149                         mode = (mode | 0777) & ~tar_umask;
 150                 } else if (S_ISLNK(mode)) {
 151                         *header.typeflag = TYPEFLAG_LNK;
 152                         mode |= 0777;
 153                 } else if (S_ISREG(mode)) {
 154                         *header.typeflag = TYPEFLAG_REG;
 155                         mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 156                 } else {
 157                         error("unsupported file mode: 0%o (SHA1: %s)",
 158                               mode, sha1_to_hex(sha1));
 159                         return;
 160                 }
 161                 if (path->len > sizeof(header.name)) {
 162                         int plen = get_path_prefix(path, sizeof(header.prefix));
 163                         int rest = path->len - plen - 1;
 164                         if (plen > 0 && rest <= sizeof(header.name)) {
 165                                 memcpy(header.prefix, path->buf, plen);
 166                                 memcpy(header.name, path->buf + plen + 1, rest);
 167                         } else {
 168                                 sprintf(header.name, "%s.data",
 169                                         sha1_to_hex(sha1));
 170                                 strbuf_append_ext_header(&ext_header, "path",
 171                                                          path->buf, path->len);
 172                         }
 173                 } else
 174                         memcpy(header.name, path->buf, path->len);
 175         }
 176
 177         if (S_ISLNK(mode) && buffer) {
 178                 if (size > sizeof(header.linkname)) {
 179                         sprintf(header.linkname, "see %s.paxheader",
 180                                 sha1_to_hex(sha1));
 181                         strbuf_append_ext_header(&ext_header, "linkpath",
 182                                                  buffer, size);
 183                 } else
 184                         memcpy(header.linkname, buffer, size);
 185         }
 186
 187         sprintf(header.mode, "%07o", mode & 07777);
 188         sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 189         sprintf(header.mtime, "%011lo", archive_time);
 190
 191         sprintf(header.uid, "%07o", 0);
 192         sprintf(header.gid, "%07o", 0);
 193         strlcpy(header.uname, "root", sizeof(header.uname));
 194         strlcpy(header.gname, "root", sizeof(header.gname));
 195         sprintf(header.devmajor, "%07o", 0);
 196         sprintf(header.devminor, "%07o", 0);
 197
 198         memcpy(header.magic, "ustar", 6);
 199         memcpy(header.version, "00", 2);
 200
 201         sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 202
 203         if (ext_header.len > 0) {
 204                 write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
 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 }
 211
 212 static void write_global_extended_header(const unsigned char *sha1)
 213 {
 214         struct strbuf ext_header;
 215
 216         strbuf_init(&ext_header, 0);
 217         strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 218         write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
 219         strbuf_release(&ext_header);
 220 }
 221
 222 static int git_tar_config(const char *var, const char *value)
 223 {
 224         if (!strcmp(var, "tar.umask")) {
 225                 if (value && !strcmp(value, "user")) {
 226                         tar_umask = umask(0);
 227                         umask(tar_umask);
 228                 } else {
 229                         tar_umask = git_config_int(var, value);
 230                 }
 231                 return 0;
 232         }
 233         return git_default_config(var, value);
 234 }
 235
 236 static int write_tar_entry(const unsigned char *sha1,
 237                            const char *base, int baselen,
 238                            const char *filename, unsigned mode, int stage)
 239 {
 240         static struct strbuf path = STRBUF_INIT;
 241         void *buffer;
 242         enum object_type type;
 243         unsigned long size;
 244
 245         strbuf_reset(&path);
 246         strbuf_grow(&path, PATH_MAX);
 247         strbuf_add(&path, base, baselen);
 248         strbuf_addstr(&path, filename);
 249         if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 250                 strbuf_addch(&path, '/');
 251                 buffer = NULL;
 252                 size = 0;
 253         } else {
 254                 buffer = sha1_file_to_archive(path.buf, sha1, mode, &type,
 255                                               &size, commit);
 256                 if (!buffer)
 257                         die("cannot read %s", sha1_to_hex(sha1));
 258         }
 259
 260         write_entry(sha1, &path, mode, buffer, size);
 261         free(buffer);
 262
 263         return READ_TREE_RECURSIVE;
 264 }
 265
 266 int write_tar_archive(struct archiver_args *args)
 267 {
 268         int plen = args->base ? strlen(args->base) : 0;
 269
 270         git_config(git_tar_config);
 271
 272         archive_time = args->time;
 273         verbose = args->verbose;
 274         commit = args->commit;
 275
 276         if (args->commit_sha1)
 277                 write_global_extended_header(args->commit_sha1);
 278
 279         if (args->base && plen > 0 && args->base[plen - 1] == '/') {
 280                 char *base = xstrdup(args->base);
 281                 int baselen = strlen(base);
 282
 283                 while (baselen > 0 && base[baselen - 1] == '/')
 284                         base[--baselen] = '\0';
 285                 write_tar_entry(args->tree->object.sha1, "", 0, base, 040777, 0);
 286                 free(base);
 287         }
 288         read_tree_recursive(args->tree, args->base, plen, 0,
 289                             args->pathspec, write_tar_entry);
 290         write_trailer();
 291
 292         return 0;
 293 }