archive-tar.c

   1 /*
   2  * Copyright (c) 2005, 2006 Rene Scharfe
   3  */
   4 #include "cache.h"
   5 #include "commit.h"
   6 #include "strbuf.h"
   7 #include "tar.h"
   8 #include "builtin.h"
   9 #include "archive.h"
  10
  11 #define RECORDSIZE      (512)
  12 #define BLOCKSIZE       (RECORDSIZE * 20)
  13
  14 static char block[BLOCKSIZE];
  15 static unsigned long offset;
  16
  17 static time_t archive_time;
  18 static int tar_umask;
  19 static int verbose;
  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 static void strbuf_append_string(struct strbuf *sb, const char *s)
  82 {
  83         int slen = strlen(s);
  84         int total = sb->len + slen;
  85         if (total > sb->alloc) {
  86                 sb->buf = xrealloc(sb->buf, total);
  87                 sb->alloc = total;
  88         }
  89         memcpy(sb->buf + sb->len, s, slen);
  90         sb->len = total;
  91 }
  92
  93 /*
  94  * pax extended header records have the format "%u %s=%s\n".  %u contains
  95  * the size of the whole string (including the %u), the first %s is the
  96  * keyword, the second one is the value.  This function constructs such a
  97  * string and appends it to a struct strbuf.
  98  */
  99 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 100                                      const char *value, unsigned int valuelen)
 101 {
 102         char *p;
 103         int len, total, tmp;
 104
 105         /* "%u %s=%s\n" */
 106         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 107         for (tmp = len; tmp > 9; tmp /= 10)
 108                 len++;
 109
 110         total = sb->len + len;
 111         if (total > sb->alloc) {
 112                 sb->buf = xrealloc(sb->buf, total);
 113                 sb->alloc = total;
 114         }
 115
 116         p = sb->buf;
 117         p += sprintf(p, "%u %s=", len, keyword);
 118         memcpy(p, value, valuelen);
 119         p += valuelen;
 120         *p = '\n';
 121         sb->len = total;
 122 }
 123
 124 static unsigned int ustar_header_chksum(const struct ustar_header *header)
 125 {
 126         char *p = (char *)header;
 127         unsigned int chksum = 0;
 128         while (p < header->chksum)
 129                 chksum += *p++;
 130         chksum += sizeof(header->chksum) * ' ';
 131         p += sizeof(header->chksum);
 132         while (p < (char *)header + sizeof(struct ustar_header))
 133                 chksum += *p++;
 134         return chksum;
 135 }
 136
 137 static int get_path_prefix(const struct strbuf *path, int maxlen)
 138 {
 139         int i = path->len;
 140         if (i > maxlen)
 141                 i = maxlen;
 142         do {
 143                 i--;
 144         } while (i > 0 && path->buf[i] != '/');
 145         return i;
 146 }
 147
 148 static void write_entry(const unsigned char *sha1, struct strbuf *path,
 149                         unsigned int mode, void *buffer, unsigned long size)
 150 {
 151         struct ustar_header header;
 152         struct strbuf ext_header;
 153
 154         memset(&header, 0, sizeof(header));
 155         ext_header.buf = NULL;
 156         ext_header.len = ext_header.alloc = 0;
 157
 158         if (!sha1) {
 159                 *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 160                 mode = 0100666;
 161                 strcpy(header.name, "pax_global_header");
 162         } else if (!path) {
 163                 *header.typeflag = TYPEFLAG_EXT_HEADER;
 164                 mode = 0100666;
 165                 sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
 166         } else {
 167                 if (verbose)
 168                         fprintf(stderr, "%.*s\n", path->len, path->buf);
 169                 if (S_ISDIR(mode)) {
 170                         *header.typeflag = TYPEFLAG_DIR;
 171                         mode = (mode | 0777) & ~tar_umask;
 172                 } else if (S_ISLNK(mode)) {
 173                         *header.typeflag = TYPEFLAG_LNK;
 174                         mode |= 0777;
 175                 } else if (S_ISREG(mode)) {
 176                         *header.typeflag = TYPEFLAG_REG;
 177                         mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 178                 } else {
 179                         error("unsupported file mode: 0%o (SHA1: %s)",
 180                               mode, sha1_to_hex(sha1));
 181                         return;
 182                 }
 183                 if (path->len > sizeof(header.name)) {
 184                         int plen = get_path_prefix(path, sizeof(header.prefix));
 185                         int rest = path->len - plen - 1;
 186                         if (plen > 0 && rest <= sizeof(header.name)) {
 187                                 memcpy(header.prefix, path->buf, plen);
 188                                 memcpy(header.name, path->buf + plen + 1, rest);
 189                         } else {
 190                                 sprintf(header.name, "%s.data",
 191                                         sha1_to_hex(sha1));
 192                                 strbuf_append_ext_header(&ext_header, "path",
 193                                                          path->buf, path->len);
 194                         }
 195                 } else
 196                         memcpy(header.name, path->buf, path->len);
 197         }
 198
 199         if (S_ISLNK(mode) && buffer) {
 200                 if (size > sizeof(header.linkname)) {
 201                         sprintf(header.linkname, "see %s.paxheader",
 202                                 sha1_to_hex(sha1));
 203                         strbuf_append_ext_header(&ext_header, "linkpath",
 204                                                  buffer, size);
 205                 } else
 206                         memcpy(header.linkname, buffer, size);
 207         }
 208
 209         sprintf(header.mode, "%07o", mode & 07777);
 210         sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
 211         sprintf(header.mtime, "%011lo", archive_time);
 212
 213         /* XXX: should we provide more meaningful info here? */
 214         sprintf(header.uid, "%07o", 0);
 215         sprintf(header.gid, "%07o", 0);
 216         strlcpy(header.uname, "git", sizeof(header.uname));
 217         strlcpy(header.gname, "git", sizeof(header.gname));
 218         sprintf(header.devmajor, "%07o", 0);
 219         sprintf(header.devminor, "%07o", 0);
 220
 221         memcpy(header.magic, "ustar", 6);
 222         memcpy(header.version, "00", 2);
 223
 224         sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
 225
 226         if (ext_header.len > 0) {
 227                 write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
 228                 free(ext_header.buf);
 229         }
 230         write_blocked(&header, sizeof(header));
 231         if (S_ISREG(mode) && buffer && size > 0)
 232                 write_blocked(buffer, size);
 233 }
 234
 235 static void write_global_extended_header(const unsigned char *sha1)
 236 {
 237         struct strbuf ext_header;
 238         ext_header.buf = NULL;
 239         ext_header.len = ext_header.alloc = 0;
 240         strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
 241         write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
 242         free(ext_header.buf);
 243 }
 244
 245 static int git_tar_config(const char *var, const char *value)
 246 {
 247         if (!strcmp(var, "tar.umask")) {
 248                 if (!strcmp(value, "user")) {
 249                         tar_umask = umask(0);
 250                         umask(tar_umask);
 251                 } else {
 252                         tar_umask = git_config_int(var, value);
 253                 }
 254                 return 0;
 255         }
 256         return git_default_config(var, value);
 257 }
 258
 259 static int write_tar_entry(const unsigned char *sha1,
 260                            const char *base, int baselen,
 261                            const char *filename, unsigned mode, int stage)
 262 {
 263         static struct strbuf path;
 264         int filenamelen = strlen(filename);
 265         void *buffer;
 266         char type[20];
 267         unsigned long size;
 268
 269         if (!path.alloc) {
 270                 path.buf = xmalloc(PATH_MAX);
 271                 path.alloc = PATH_MAX;
 272                 path.len = path.eof = 0;
 273         }
 274         if (path.alloc < baselen + filenamelen) {
 275                 free(path.buf);
 276                 path.buf = xmalloc(baselen + filenamelen);
 277                 path.alloc = baselen + filenamelen;
 278         }
 279         memcpy(path.buf, base, baselen);
 280         memcpy(path.buf + baselen, filename, filenamelen);
 281         path.len = baselen + filenamelen;
 282         if (S_ISDIR(mode)) {
 283                 strbuf_append_string(&path, "/");
 284                 buffer = NULL;
 285                 size = 0;
 286         } else {
 287                 buffer = read_sha1_file(sha1, type, &size);
 288                 if (!buffer)
 289                         die("cannot read %s", sha1_to_hex(sha1));
 290         }
 291
 292         write_entry(sha1, &path, mode, buffer, size);
 293         free(buffer);
 294
 295         return READ_TREE_RECURSIVE;
 296 }
 297
 298 int write_tar_archive(struct archiver_args *args)
 299 {
 300         int plen = args->base ? strlen(args->base) : 0;
 301
 302         git_config(git_tar_config);
 303
 304         archive_time = args->time;
 305         verbose = args->verbose;
 306
 307         if (args->commit_sha1)
 308                 write_global_extended_header(args->commit_sha1);
 309
 310         if (args->base && plen > 0 && args->base[plen - 1] == '/') {
 311                 char *base = xstrdup(args->base);
 312                 int baselen = strlen(base);
 313
 314                 while (baselen > 0 && base[baselen - 1] == '/')
 315                         base[--baselen] = '\0';
 316                 write_tar_entry(args->tree->object.sha1, "", 0, base, 040777, 0);
 317                 free(base);
 318         }
 319         read_tree_recursive(args->tree, args->base, plen, 0,
 320                             args->pathspec, write_tar_entry);
 321         write_trailer();
 322
 323         return 0;
 324 }