contrib/libarchive-2/libarchive/archive_write_set_format_ustar.c

   1 /*-
   2  * Copyright (c) 2003-2007 Tim Kientzle
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "archive_platform.h"
  27 __FBSDID("$FreeBSD: src/lib/libarchive/archive_write_set_format_ustar.c,v 1.27 2008/05/26 17:00:23 kientzle Exp $");
  28
  29
  30 #ifdef HAVE_ERRNO_H
  31 #include <errno.h>
  32 #endif
  33 #include <stdio.h>
  34 #ifdef HAVE_STDLIB_H
  35 #include <stdlib.h>
  36 #endif
  37 #ifdef HAVE_STRING_H
  38 #include <string.h>
  39 #endif
  40
  41 #include "archive.h"
  42 #include "archive_entry.h"
  43 #include "archive_private.h"
  44 #include "archive_write_private.h"
  45
  46 struct ustar {
  47         uint64_t        entry_bytes_remaining;
  48         uint64_t        entry_padding;
  49 };
  50
  51 /*
  52  * Define structure of POSIX 'ustar' tar header.
  53  */
  54 #define USTAR_name_offset 0
  55 #define USTAR_name_size 100
  56 #define USTAR_mode_offset 100
  57 #define USTAR_mode_size 6
  58 #define USTAR_mode_max_size 8
  59 #define USTAR_uid_offset 108
  60 #define USTAR_uid_size 6
  61 #define USTAR_uid_max_size 8
  62 #define USTAR_gid_offset 116
  63 #define USTAR_gid_size 6
  64 #define USTAR_gid_max_size 8
  65 #define USTAR_size_offset 124
  66 #define USTAR_size_size 11
  67 #define USTAR_size_max_size 12
  68 #define USTAR_mtime_offset 136
  69 #define USTAR_mtime_size 11
  70 #define USTAR_mtime_max_size 11
  71 #define USTAR_checksum_offset 148
  72 #define USTAR_checksum_size 8
  73 #define USTAR_typeflag_offset 156
  74 #define USTAR_typeflag_size 1
  75 #define USTAR_linkname_offset 157
  76 #define USTAR_linkname_size 100
  77 #define USTAR_magic_offset 257
  78 #define USTAR_magic_size 6
  79 #define USTAR_version_offset 263
  80 #define USTAR_version_size 2
  81 #define USTAR_uname_offset 265
  82 #define USTAR_uname_size 32
  83 #define USTAR_gname_offset 297
  84 #define USTAR_gname_size 32
  85 #define USTAR_rdevmajor_offset 329
  86 #define USTAR_rdevmajor_size 6
  87 #define USTAR_rdevmajor_max_size 8
  88 #define USTAR_rdevminor_offset 337
  89 #define USTAR_rdevminor_size 6
  90 #define USTAR_rdevminor_max_size 8
  91 #define USTAR_prefix_offset 345
  92 #define USTAR_prefix_size 155
  93 #define USTAR_padding_offset 500
  94 #define USTAR_padding_size 12
  95
  96 /*
  97  * A filled-in copy of the header for initialization.
  98  */
  99 static const char template_header[] = {
 100         /* name: 100 bytes */
 101         0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 102         0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 103         0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 104         0,0,0,0,
 105         /* Mode, space-null termination: 8 bytes */
 106         '0','0','0','0','0','0', ' ','\0',
 107         /* uid, space-null termination: 8 bytes */
 108         '0','0','0','0','0','0', ' ','\0',
 109         /* gid, space-null termination: 8 bytes */
 110         '0','0','0','0','0','0', ' ','\0',
 111         /* size, space termation: 12 bytes */
 112         '0','0','0','0','0','0','0','0','0','0','0', ' ',
 113         /* mtime, space termation: 12 bytes */
 114         '0','0','0','0','0','0','0','0','0','0','0', ' ',
 115         /* Initial checksum value: 8 spaces */
 116         ' ',' ',' ',' ',' ',' ',' ',' ',
 117         /* Typeflag: 1 byte */
 118         '0',                    /* '0' = regular file */
 119         /* Linkname: 100 bytes */
 120         0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 121         0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 122         0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 123         0,0,0,0,
 124         /* Magic: 6 bytes, Version: 2 bytes */
 125         'u','s','t','a','r','\0', '0','0',
 126         /* Uname: 32 bytes */
 127         0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 128         /* Gname: 32 bytes */
 129         0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 130         /* rdevmajor + space/null padding: 8 bytes */
 131         '0','0','0','0','0','0', ' ','\0',
 132         /* rdevminor + space/null padding: 8 bytes */
 133         '0','0','0','0','0','0', ' ','\0',
 134         /* Prefix: 155 bytes */
 135         0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 136         0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 137         0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 138         0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
 139         0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,
 140         /* Padding: 12 bytes */
 141         0,0,0,0,0,0,0,0, 0,0,0,0
 142 };
 143
 144 static ssize_t  archive_write_ustar_data(struct archive_write *a, const void *buff,
 145                     size_t s);
 146 static int      archive_write_ustar_destroy(struct archive_write *);
 147 static int      archive_write_ustar_finish(struct archive_write *);
 148 static int      archive_write_ustar_finish_entry(struct archive_write *);
 149 static int      archive_write_ustar_header(struct archive_write *,
 150                     struct archive_entry *entry);
 151 static int      format_256(int64_t, char *, int);
 152 static int      format_number(int64_t, char *, int size, int max, int strict);
 153 static int      format_octal(int64_t, char *, int);
 154 static int      write_nulls(struct archive_write *a, size_t);
 155
 156 /*
 157  * Set output format to 'ustar' format.
 158  */
 159 int
 160 archive_write_set_format_ustar(struct archive *_a)
 161 {
 162         struct archive_write *a = (struct archive_write *)_a;
 163         struct ustar *ustar;
 164
 165         /* If someone else was already registered, unregister them. */
 166         if (a->format_destroy != NULL)
 167                 (a->format_destroy)(a);
 168
 169         /* Basic internal sanity test. */
 170         if (sizeof(template_header) != 512) {
 171                 archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC, "Internal: template_header wrong size: %d should be 512", sizeof(template_header));
 172                 return (ARCHIVE_FATAL);
 173         }
 174
 175         ustar = (struct ustar *)malloc(sizeof(*ustar));
 176         if (ustar == NULL) {
 177                 archive_set_error(&a->archive, ENOMEM, "Can't allocate ustar data");
 178                 return (ARCHIVE_FATAL);
 179         }
 180         memset(ustar, 0, sizeof(*ustar));
 181         a->format_data = ustar;
 182
 183         a->pad_uncompressed = 1;        /* Mimic gtar in this respect. */
 184         a->format_write_header = archive_write_ustar_header;
 185         a->format_write_data = archive_write_ustar_data;
 186         a->format_finish = archive_write_ustar_finish;
 187         a->format_destroy = archive_write_ustar_destroy;
 188         a->format_finish_entry = archive_write_ustar_finish_entry;
 189         a->archive.archive_format = ARCHIVE_FORMAT_TAR_USTAR;
 190         a->archive.archive_format_name = "POSIX ustar";
 191         return (ARCHIVE_OK);
 192 }
 193
 194 static int
 195 archive_write_ustar_header(struct archive_write *a, struct archive_entry *entry)
 196 {
 197         char buff[512];
 198         int ret, ret2;
 199         struct ustar *ustar;
 200
 201         ustar = (struct ustar *)a->format_data;
 202
 203         /* Only regular files (not hardlinks) have data. */
 204         if (archive_entry_hardlink(entry) != NULL ||
 205             archive_entry_symlink(entry) != NULL ||
 206             !(archive_entry_filetype(entry) == AE_IFREG))
 207                 archive_entry_set_size(entry, 0);
 208
 209         if (AE_IFDIR == archive_entry_filetype(entry)) {
 210                 const char *p;
 211                 char *t;
 212                 /*
 213                  * Ensure a trailing '/'.  Modify the entry so
 214                  * the client sees the change.
 215                  */
 216                 p = archive_entry_pathname(entry);
 217                 if (p[strlen(p) - 1] != '/') {
 218                         t = (char *)malloc(strlen(p) + 2);
 219                         if (t == NULL) {
 220                                 archive_set_error(&a->archive, ENOMEM,
 221                                 "Can't allocate ustar data");
 222                                 return(ARCHIVE_FATAL);
 223                         }
 224                         strcpy(t, p);
 225                         strcat(t, "/");
 226                         archive_entry_copy_pathname(entry, t);
 227                         free(t);
 228                 }
 229         }
 230
 231         ret = __archive_write_format_header_ustar(a, buff, entry, -1, 1);
 232         if (ret < ARCHIVE_WARN)
 233                 return (ret);
 234         ret2 = (a->compressor.write)(a, buff, 512);
 235         if (ret2 < ARCHIVE_WARN)
 236                 return (ret2);
 237         if (ret2 < ret)
 238                 ret = ret2;
 239
 240         ustar->entry_bytes_remaining = archive_entry_size(entry);
 241         ustar->entry_padding = 0x1ff & (-(int64_t)ustar->entry_bytes_remaining);
 242         return (ret);
 243 }
 244
 245 /*
 246  * Format a basic 512-byte "ustar" header.
 247  *
 248  * Returns -1 if format failed (due to field overflow).
 249  * Note that this always formats as much of the header as possible.
 250  * If "strict" is set to zero, it will extend numeric fields as
 251  * necessary (overwriting terminators or using base-256 extensions).
 252  *
 253  * This is exported so that other 'tar' formats can use it.
 254  */
 255 int
 256 __archive_write_format_header_ustar(struct archive_write *a, char h[512],
 257     struct archive_entry *entry, int tartype, int strict)
 258 {
 259         unsigned int checksum;
 260         int i, ret;
 261         size_t copy_length;
 262         const char *p, *pp;
 263         int mytartype;
 264
 265         ret = 0;
 266         mytartype = -1;
 267         /*
 268          * The "template header" already includes the "ustar"
 269          * signature, various end-of-field markers and other required
 270          * elements.
 271          */
 272         memcpy(h, &template_header, 512);
 273
 274         /*
 275          * Because the block is already null-filled, and strings
 276          * are allowed to exactly fill their destination (without null),
 277          * I use memcpy(dest, src, strlen()) here a lot to copy strings.
 278          */
 279
 280         pp = archive_entry_pathname(entry);
 281         if (strlen(pp) <= USTAR_name_size)
 282                 memcpy(h + USTAR_name_offset, pp, strlen(pp));
 283         else {
 284                 /* Store in two pieces, splitting at a '/'. */
 285                 p = strchr(pp + strlen(pp) - USTAR_name_size - 1, '/');
 286                 /*
 287                  * Look for the next '/' if we chose the first character
 288                  * as the separator.  (ustar format doesn't permit
 289                  * an empty prefix.)
 290                  */
 291                 if (p == pp)
 292                         p = strchr(p + 1, '/');
 293                 /* Fail if the name won't fit. */
 294                 if (!p) {
 295                         /* No separator. */
 296                         archive_set_error(&a->archive, ENAMETOOLONG,
 297                             "Pathname too long");
 298                         ret = ARCHIVE_FAILED;
 299                 } else if (p[1] == '\0') {
 300                         /*
 301                          * The only feasible separator is a final '/';
 302                          * this would result in a non-empty prefix and
 303                          * an empty name, which POSIX doesn't
 304                          * explicity forbid, but it just feels wrong.
 305                          */
 306                         archive_set_error(&a->archive, ENAMETOOLONG,
 307                             "Pathname too long");
 308                         ret = ARCHIVE_FAILED;
 309                 } else if (p  > pp + USTAR_prefix_size) {
 310                         /* Prefix is too long. */
 311                         archive_set_error(&a->archive, ENAMETOOLONG,
 312                             "Pathname too long");
 313                         ret = ARCHIVE_FAILED;
 314                 } else {
 315                         /* Copy prefix and remainder to appropriate places */
 316                         memcpy(h + USTAR_prefix_offset, pp, p - pp);
 317                         memcpy(h + USTAR_name_offset, p + 1, pp + strlen(pp) - p - 1);
 318                 }
 319         }
 320
 321         p = archive_entry_hardlink(entry);
 322         if (p != NULL)
 323                 mytartype = '1';
 324         else
 325                 p = archive_entry_symlink(entry);
 326         if (p != NULL && p[0] != '\0') {
 327                 copy_length = strlen(p);
 328                 if (copy_length > USTAR_linkname_size) {
 329                         archive_set_error(&a->archive, ENAMETOOLONG,
 330                             "Link contents too long");
 331                         ret = ARCHIVE_FAILED;
 332                         copy_length = USTAR_linkname_size;
 333                 }
 334                 memcpy(h + USTAR_linkname_offset, p, copy_length);
 335         }
 336
 337         p = archive_entry_uname(entry);
 338         if (p != NULL && p[0] != '\0') {
 339                 copy_length = strlen(p);
 340                 if (copy_length > USTAR_uname_size) {
 341                         archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
 342                             "Username too long");
 343                         ret = ARCHIVE_FAILED;
 344                         copy_length = USTAR_uname_size;
 345                 }
 346                 memcpy(h + USTAR_uname_offset, p, copy_length);
 347         }
 348
 349         p = archive_entry_gname(entry);
 350         if (p != NULL && p[0] != '\0') {
 351                 copy_length = strlen(p);
 352                 if (strlen(p) > USTAR_gname_size) {
 353                         archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
 354                             "Group name too long");
 355                         ret = ARCHIVE_FAILED;
 356                         copy_length = USTAR_gname_size;
 357                 }
 358                 memcpy(h + USTAR_gname_offset, p, copy_length);
 359         }
 360
 361         if (format_number(archive_entry_mode(entry) & 07777, h + USTAR_mode_offset, USTAR_mode_size, USTAR_mode_max_size, strict)) {
 362                 archive_set_error(&a->archive, ERANGE, "Numeric mode too large");
 363                 ret = ARCHIVE_FAILED;
 364         }
 365
 366         if (format_number(archive_entry_uid(entry), h + USTAR_uid_offset, USTAR_uid_size, USTAR_uid_max_size, strict)) {
 367                 archive_set_error(&a->archive, ERANGE, "Numeric user ID too large");
 368                 ret = ARCHIVE_FAILED;
 369         }
 370
 371         if (format_number(archive_entry_gid(entry), h + USTAR_gid_offset, USTAR_gid_size, USTAR_gid_max_size, strict)) {
 372                 archive_set_error(&a->archive, ERANGE, "Numeric group ID too large");
 373                 ret = ARCHIVE_FAILED;
 374         }
 375
 376         if (format_number(archive_entry_size(entry), h + USTAR_size_offset, USTAR_size_size, USTAR_size_max_size, strict)) {
 377                 archive_set_error(&a->archive, ERANGE, "File size out of range");
 378                 ret = ARCHIVE_FAILED;
 379         }
 380
 381         if (format_number(archive_entry_mtime(entry), h + USTAR_mtime_offset, USTAR_mtime_size, USTAR_mtime_max_size, strict)) {
 382                 archive_set_error(&a->archive, ERANGE,
 383                     "File modification time too large");
 384                 ret = ARCHIVE_FAILED;
 385         }
 386
 387         if (archive_entry_filetype(entry) == AE_IFBLK
 388             || archive_entry_filetype(entry) == AE_IFCHR) {
 389                 if (format_number(archive_entry_rdevmajor(entry), h + USTAR_rdevmajor_offset,
 390                         USTAR_rdevmajor_size, USTAR_rdevmajor_max_size, strict)) {
 391                         archive_set_error(&a->archive, ERANGE,
 392                             "Major device number too large");
 393                         ret = ARCHIVE_FAILED;
 394                 }
 395
 396                 if (format_number(archive_entry_rdevminor(entry), h + USTAR_rdevminor_offset,
 397                         USTAR_rdevminor_size, USTAR_rdevminor_max_size, strict)) {
 398                         archive_set_error(&a->archive, ERANGE,
 399                             "Minor device number too large");
 400                         ret = ARCHIVE_FAILED;
 401                 }
 402         }
 403
 404         if (tartype >= 0) {
 405                 h[USTAR_typeflag_offset] = tartype;
 406         } else if (mytartype >= 0) {
 407                 h[USTAR_typeflag_offset] = mytartype;
 408         } else {
 409                 switch (archive_entry_filetype(entry)) {
 410                 case AE_IFREG: h[USTAR_typeflag_offset] = '0' ; break;
 411                 case AE_IFLNK: h[USTAR_typeflag_offset] = '2' ; break;
 412                 case AE_IFCHR: h[USTAR_typeflag_offset] = '3' ; break;
 413                 case AE_IFBLK: h[USTAR_typeflag_offset] = '4' ; break;
 414                 case AE_IFDIR: h[USTAR_typeflag_offset] = '5' ; break;
 415                 case AE_IFIFO: h[USTAR_typeflag_offset] = '6' ; break;
 416                 default:
 417                         archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
 418                             "tar format cannot archive this (mode=0%lo)",
 419                             (unsigned long)archive_entry_mode(entry));
 420                         ret = ARCHIVE_FAILED;
 421                 }
 422         }
 423
 424         checksum = 0;
 425         for (i = 0; i < 512; i++)
 426                 checksum += 255 & (unsigned int)h[i];
 427         h[USTAR_checksum_offset + 6] = '\0'; /* Can't be pre-set in the template. */
 428         /* h[USTAR_checksum_offset + 7] = ' '; */ /* This is pre-set in the template. */
 429         format_octal(checksum, h + USTAR_checksum_offset, 6);
 430         return (ret);
 431 }
 432
 433 /*
 434  * Format a number into a field, with some intelligence.
 435  */
 436 static int
 437 format_number(int64_t v, char *p, int s, int maxsize, int strict)
 438 {
 439         int64_t limit;
 440
 441         limit = ((int64_t)1 << (s*3));
 442
 443         /* "Strict" only permits octal values with proper termination. */
 444         if (strict)
 445                 return (format_octal(v, p, s));
 446
 447         /*
 448          * In non-strict mode, we allow the number to overwrite one or
 449          * more bytes of the field termination.  Even old tar
 450          * implementations should be able to handle this with no
 451          * problem.
 452          */
 453         if (v >= 0) {
 454                 while (s <= maxsize) {
 455                         if (v < limit)
 456                                 return (format_octal(v, p, s));
 457                         s++;
 458                         limit <<= 3;
 459                 }
 460         }
 461
 462         /* Base-256 can handle any number, positive or negative. */
 463         return (format_256(v, p, maxsize));
 464 }
 465
 466 /*
 467  * Format a number into the specified field using base-256.
 468  */
 469 static int
 470 format_256(int64_t v, char *p, int s)
 471 {
 472         p += s;
 473         while (s-- > 0) {
 474                 *--p = (char)(v & 0xff);
 475                 v >>= 8;
 476         }
 477         *p |= 0x80; /* Set the base-256 marker bit. */
 478         return (0);
 479 }
 480
 481 /*
 482  * Format a number into the specified field.
 483  */
 484 static int
 485 format_octal(int64_t v, char *p, int s)
 486 {
 487         int len;
 488
 489         len = s;
 490
 491         /* Octal values can't be negative, so use 0. */
 492         if (v < 0) {
 493                 while (len-- > 0)
 494                         *p++ = '0';
 495                 return (-1);
 496         }
 497
 498         p += s;         /* Start at the end and work backwards. */
 499         while (s-- > 0) {
 500                 *--p = (char)('0' + (v & 7));
 501                 v >>= 3;
 502         }
 503
 504         if (v == 0)
 505                 return (0);
 506
 507         /* If it overflowed, fill field with max value. */
 508         while (len-- > 0)
 509                 *p++ = '7';
 510
 511         return (-1);
 512 }
 513
 514 static int
 515 archive_write_ustar_finish(struct archive_write *a)
 516 {
 517         int r;
 518
 519         if (a->compressor.write == NULL)
 520                 return (ARCHIVE_OK);
 521
 522         r = write_nulls(a, 512*2);
 523         return (r);
 524 }
 525
 526 static int
 527 archive_write_ustar_destroy(struct archive_write *a)
 528 {
 529         struct ustar *ustar;
 530
 531         ustar = (struct ustar *)a->format_data;
 532         free(ustar);
 533         a->format_data = NULL;
 534         return (ARCHIVE_OK);
 535 }
 536
 537 static int
 538 archive_write_ustar_finish_entry(struct archive_write *a)
 539 {
 540         struct ustar *ustar;
 541         int ret;
 542
 543         ustar = (struct ustar *)a->format_data;
 544         ret = write_nulls(a,
 545             ustar->entry_bytes_remaining + ustar->entry_padding);
 546         ustar->entry_bytes_remaining = ustar->entry_padding = 0;
 547         return (ret);
 548 }
 549
 550 static int
 551 write_nulls(struct archive_write *a, size_t padding)
 552 {
 553         int ret;
 554         size_t to_write;
 555
 556         while (padding > 0) {
 557                 to_write = padding < a->null_length ? padding : a->null_length;
 558                 ret = (a->compressor.write)(a, a->nulls, to_write);
 559                 if (ret != ARCHIVE_OK)
 560                         return (ret);
 561                 padding -= to_write;
 562         }
 563         return (ARCHIVE_OK);
 564 }
 565
 566 static ssize_t
 567 archive_write_ustar_data(struct archive_write *a, const void *buff, size_t s)
 568 {
 569         struct ustar *ustar;
 570         int ret;
 571
 572         ustar = (struct ustar *)a->format_data;
 573         if (s > ustar->entry_bytes_remaining)
 574                 s = ustar->entry_bytes_remaining;
 575         ret = (a->compressor.write)(a, buff, s);
 576         ustar->entry_bytes_remaining -= s;
 577         if (ret != ARCHIVE_OK)
 578                 return (ret);
 579         return (s);
 580 }