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 int tar_umask = 002;
  17
  18 /* writes out the whole block, but only if it is full */
  19 static 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  */
  31 static 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  */
  67 static 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  */
  84 static 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
 100 static 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
 113 static 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
 124 static 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
 213 static 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
 227 static 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
 241 int 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 }