X-Git-Url: https://git.dogcows.com/gitweb?p=chaz%2Ftar;a=blobdiff_plain;f=src%2Fsparse.c;h=6a976763419e78a5d5041fe3a01046e787dccdc8;hp=c8ff6b90f656f5c98d4f6a5aa09a474c8d23f86d;hb=45ccda119355a1087450039a250359c1d0de0d08;hpb=b320151a23fcbcc07f3bbdadaeec554830eb12fd

diff --git a/src/sparse.c b/src/sparse.c
index c8ff6b9..6a97676 100644
--- a/src/sparse.c
+++ b/src/sparse.c
@@ -1,10 +1,10 @@
 /* Functions for dealing with sparse files
 
-   Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
+   Copyright 2003-2007, 2010, 2013-2014 Free Software Foundation, Inc.
 
    This program is free software; you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by the
-   Free Software Foundation; either version 2, or (at your option) any later
+   Free Software Foundation; either version 3, or (at your option) any later
    version.
 
    This program is distributed in the hope that it will be useful, but
@@ -13,14 +13,15 @@
    Public License for more details.
 
    You should have received a copy of the GNU General Public License along
-   with this program; if not, write to the Free Software Foundation, Inc.,
-   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+   with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include <system.h>
+#include <inttostr.h>
 #include <quotearg.h>
 #include "common.h"
 
 struct tar_sparse_file;
+static bool sparse_select_optab (struct tar_sparse_file *file);
 
 enum sparse_scan_state
   {
@@ -47,47 +48,47 @@ struct tar_sparse_file
 {
   int fd;                           /* File descriptor */
   bool seekable;                    /* Is fd seekable? */
-  size_t offset;                    /* Current offset in fd if seekable==false.
+  off_t offset;                     /* Current offset in fd if seekable==false.
 				       Otherwise unused */
-  size_t dumped_size;               /* Number of bytes actually written
+  off_t dumped_size;                /* Number of bytes actually written
 				       to the archive */
   struct tar_stat_info *stat_info;  /* Information about the file */
-  struct tar_sparse_optab *optab;
+  struct tar_sparse_optab const *optab; /* Operation table */
   void *closure;                    /* Any additional data optab calls might
-				       reqiure */
+				       require */
 };
 
 /* Dump zeros to file->fd until offset is reached. It is used instead of
    lseek if the output file is not seekable */
-static long
+static bool
 dump_zeros (struct tar_sparse_file *file, off_t offset)
 {
-  char buf[BLOCKSIZE];
-  
-  if (offset - file->offset < 0)
+  static char const zero_buf[BLOCKSIZE];
+
+  if (offset < file->offset)
     {
       errno = EINVAL;
-      return -1;
+      return false;
     }
 
-  memset (buf, 0, sizeof buf);
   while (file->offset < offset)
     {
-      size_t size = offset - file->offset;
-      size_t wrbytes;
-      
-      if (size > sizeof buf)
-	size = sizeof buf;
-      wrbytes = write (file->fd, buf, size);
+      size_t size = (BLOCKSIZE < offset - file->offset
+		     ? BLOCKSIZE
+		     : offset - file->offset);
+      ssize_t wrbytes;
+
+      wrbytes = write (file->fd, zero_buf, size);
       if (wrbytes <= 0)
 	{
 	  if (wrbytes == 0)
 	    errno = EINVAL;
-	  return -1;
+	  return false;
 	}
       file->offset += wrbytes;
     }
-  return file->offset;
+
+  return true;
 }
 
 static bool
@@ -101,9 +102,14 @@ tar_sparse_member_p (struct tar_sparse_file *file)
 static bool
 tar_sparse_init (struct tar_sparse_file *file)
 {
-  file->dumped_size = 0;
+  memset (file, 0, sizeof *file);
+
+  if (!sparse_select_optab (file))
+    return false;
+
   if (file->optab->init)
     return file->optab->init (file);
+
   return true;
 }
 
@@ -168,14 +174,9 @@ tar_sparse_fixup_header (struct tar_sparse_file *file)
 static bool
 lseek_or_error (struct tar_sparse_file *file, off_t offset)
 {
-  off_t off;
-
-  if (file->seekable)
-    off = lseek (file->fd, offset, SEEK_SET);
-  else
-    off = dump_zeros (file, offset);
-  
-  if (off < 0)
+  if (file->seekable
+      ? lseek (file->fd, offset, SEEK_SET) < 0
+      : ! dump_zeros (file, offset))
     {
       seek_diag_details (file->stat_info->orig_file_name, offset);
       return false;
@@ -187,7 +188,7 @@ lseek_or_error (struct tar_sparse_file *file, off_t offset)
    it's made *entirely* of zeros, returning a 0 the instant it finds
    something that is a nonzero, i.e., useful data.  */
 static bool
-zero_block_p (char *buffer, size_t size)
+zero_block_p (char const *buffer, size_t size)
 {
   while (size--)
     if (*buffer++)
@@ -195,88 +196,77 @@ zero_block_p (char *buffer, size_t size)
   return true;
 }
 
-#define clear_block(p) memset (p, 0, BLOCKSIZE);
-
-#define SPARSES_INIT_COUNT SPARSES_IN_SPARSE_HEADER
-
 static void
-sparse_add_map (struct tar_sparse_file *file, struct sp_array *sp)
+sparse_add_map (struct tar_stat_info *st, struct sp_array const *sp)
 {
-  if (file->stat_info->sparse_map == NULL)
-    {
-      file->stat_info->sparse_map =
-	xmalloc (SPARSES_INIT_COUNT * sizeof file->stat_info->sparse_map[0]);
-      file->stat_info->sparse_map_size = SPARSES_INIT_COUNT;
-    }
-  else if (file->stat_info->sparse_map_avail == file->stat_info->sparse_map_size)
-    {
-      file->stat_info->sparse_map_size *= 2;
-      file->stat_info->sparse_map =
-	xrealloc (file->stat_info->sparse_map,
-		  file->stat_info->sparse_map_size
-		  * sizeof file->stat_info->sparse_map[0]);
-    }
-  file->stat_info->sparse_map[file->stat_info->sparse_map_avail++] = *sp;
+  struct sp_array *sparse_map = st->sparse_map;
+  size_t avail = st->sparse_map_avail;
+  if (avail == st->sparse_map_size)
+    st->sparse_map = sparse_map =
+      x2nrealloc (sparse_map, &st->sparse_map_size, sizeof *sparse_map);
+  sparse_map[avail] = *sp;
+  st->sparse_map_avail = avail + 1;
 }
 
 /* Scan the sparse file and create its map */
 static bool
 sparse_scan_file (struct tar_sparse_file *file)
 {
-  static char buffer[BLOCKSIZE];
-  size_t count;
+  struct tar_stat_info *st = file->stat_info;
+  int fd = file->fd;
+  char buffer[BLOCKSIZE];
+  size_t count = 0;
   off_t offset = 0;
   struct sp_array sp = {0, 0};
 
-  if (!lseek_or_error (file, 0))
-    return false;
-  clear_block (buffer);
-
-  file->stat_info->sparse_map_avail = 0;
-  file->stat_info->archive_file_size = 0;
+  st->archive_file_size = 0;
 
-  if (!tar_sparse_scan (file, scan_begin, NULL))
-    return false;
-
-  while ((count = safe_read (file->fd, buffer, sizeof buffer)) != 0
-	 && count != SAFE_READ_ERROR)
+  if (ST_NBLOCKS (st->stat) == 0)
+    offset = st->stat.st_size;
+  else
     {
-      /* Analize the block */
-      if (zero_block_p (buffer, count))
+      if (!tar_sparse_scan (file, scan_begin, NULL))
+	return false;
+
+      while ((count = blocking_read (fd, buffer, sizeof buffer)) != 0
+	     && count != SAFE_READ_ERROR)
 	{
-	  if (sp.numbytes)
+	  /* Analyze the block.  */
+	  if (zero_block_p (buffer, count))
+	    {
+	      if (sp.numbytes)
+		{
+		  sparse_add_map (st, &sp);
+		  sp.numbytes = 0;
+		  if (!tar_sparse_scan (file, scan_block, NULL))
+		    return false;
+		}
+	    }
+	  else
 	    {
-	      sparse_add_map (file, &sp);
-	      sp.numbytes = 0;
-	      if (!tar_sparse_scan (file, scan_block, NULL))
+	      if (sp.numbytes == 0)
+		sp.offset = offset;
+	      sp.numbytes += count;
+	      st->archive_file_size += count;
+	      if (!tar_sparse_scan (file, scan_block, buffer))
 		return false;
 	    }
-	}
-      else
-	{
-	  if (sp.numbytes == 0)
-	    sp.offset = offset;
-	  sp.numbytes += count;
-	  file->stat_info->archive_file_size += count;
-	  if (!tar_sparse_scan (file, scan_block, buffer))
-	    return false;
-	}
 
-      offset += count;
-      clear_block (buffer);
+	  offset += count;
+	}
     }
 
   if (sp.numbytes == 0)
     sp.offset = offset;
 
-  sparse_add_map (file, &sp);
-  file->stat_info->archive_file_size += count;
+  sparse_add_map (st, &sp);
+  st->archive_file_size += count;
   return tar_sparse_scan (file, scan_end, NULL);
 }
 
-static struct tar_sparse_optab oldgnu_optab;
-static struct tar_sparse_optab star_optab;
-static struct tar_sparse_optab pax_optab;
+static struct tar_sparse_optab const oldgnu_optab;
+static struct tar_sparse_optab const star_optab;
+static struct tar_sparse_optab const pax_optab;
 
 static bool
 sparse_select_optab (struct tar_sparse_file *file)
@@ -321,18 +311,18 @@ sparse_dump_region (struct tar_sparse_file *file, size_t i)
       size_t bytes_read;
 
       blk = find_next_block ();
-      memset (blk->buffer, 0, BLOCKSIZE);
       bytes_read = safe_read (file->fd, blk->buffer, bufsize);
       if (bytes_read == SAFE_READ_ERROR)
 	{
           read_diag_details (file->stat_info->orig_file_name,
-	                     file->stat_info->sparse_map[i].offset
-	                         + file->stat_info->sparse_map[i].numbytes
-	                         - bytes_left,
-	             bufsize);
+	                     (file->stat_info->sparse_map[i].offset
+			      + file->stat_info->sparse_map[i].numbytes
+			      - bytes_left),
+			     bufsize);
 	  return false;
 	}
 
+      memset (blk->buffer + bytes_read, 0, BLOCKSIZE - bytes_read);
       bytes_left -= bytes_read;
       file->dumped_size += bytes_read;
       set_next_block_after (blk);
@@ -344,7 +334,7 @@ sparse_dump_region (struct tar_sparse_file *file, size_t i)
 static bool
 sparse_extract_region (struct tar_sparse_file *file, size_t i)
 {
-  size_t write_size;
+  off_t write_size;
 
   if (!lseek_or_error (file, file->stat_info->sparse_map[i].offset))
     return false;
@@ -368,9 +358,10 @@ sparse_extract_region (struct tar_sparse_file *file, size_t i)
 	  return false;
 	}
       set_next_block_after (blk);
-      count = full_write (file->fd, blk->buffer, wrbytes);
+      count = blocking_write (file->fd, blk->buffer, wrbytes);
       write_size -= count;
       file->dumped_size += count;
+      mv_size_left (file->stat_info->archive_file_size - file->dumped_size);
       file->offset += count;
       if (count != wrbytes)
 	{
@@ -391,14 +382,12 @@ sparse_dump_file (int fd, struct tar_stat_info *st)
   bool rc;
   struct tar_sparse_file file;
 
+  if (!tar_sparse_init (&file))
+    return dump_status_not_implemented;
+
   file.stat_info = st;
   file.fd = fd;
   file.seekable = true; /* File *must* be seekable for dump to work */
-  file.offset = 0;
-  
-  if (!sparse_select_optab (&file)
-      || !tar_sparse_init (&file))
-    return dump_status_not_implemented;
 
   rc = sparse_scan_file (&file);
   if (rc && file.optab->dump_region)
@@ -409,30 +398,24 @@ sparse_dump_file (int fd, struct tar_stat_info *st)
 	{
 	  size_t i;
 
+	  mv_begin_write (file.stat_info->file_name,
+		          file.stat_info->stat.st_size,
+		          file.stat_info->archive_file_size - file.dumped_size);
 	  for (i = 0; rc && i < file.stat_info->sparse_map_avail; i++)
 	    rc = tar_sparse_dump_region (&file, i);
 	}
     }
 
-  pad_archive(file.stat_info->archive_file_size - file.dumped_size);
+  pad_archive (file.stat_info->archive_file_size - file.dumped_size);
   return (tar_sparse_done (&file) && rc) ? dump_status_ok : dump_status_short;
 }
 
-/* Returns true if the file represented by stat is a sparse one */
-bool
-sparse_file_p (struct tar_stat_info *st)
-{
-  return (ST_NBLOCKS (st->stat)
-	  < (st->stat.st_size / ST_NBLOCKSIZE
-	     + (st->stat.st_size % ST_NBLOCKSIZE != 0)));
-}
-
 bool
 sparse_member_p (struct tar_stat_info *st)
 {
   struct tar_sparse_file file;
 
-  if (!sparse_select_optab (&file))
+  if (!tar_sparse_init (&file))
     return false;
   file.stat_info = st;
   return tar_sparse_member_p (&file);
@@ -443,7 +426,7 @@ sparse_fixup_header (struct tar_stat_info *st)
 {
   struct tar_sparse_file file;
 
-  if (!sparse_select_optab (&file))
+  if (!tar_sparse_init (&file))
     return false;
   file.stat_info = st;
   return tar_sparse_fixup_header (&file);
@@ -456,14 +439,13 @@ sparse_extract_file (int fd, struct tar_stat_info *st, off_t *size)
   struct tar_sparse_file file;
   size_t i;
 
+  if (!tar_sparse_init (&file))
+    return dump_status_not_implemented;
+
   file.stat_info = st;
   file.fd = fd;
   file.seekable = lseek (fd, 0, SEEK_SET) == 0;
   file.offset = 0;
-  
-  if (!sparse_select_optab (&file)
-      || !tar_sparse_init (&file))
-    return dump_status_not_implemented;
 
   rc = tar_sparse_decode_header (&file);
   for (i = 0; rc && i < file.stat_info->sparse_map_avail; i++)
@@ -478,21 +460,18 @@ sparse_skip_file (struct tar_stat_info *st)
   bool rc = true;
   struct tar_sparse_file file;
 
+  if (!tar_sparse_init (&file))
+    return dump_status_not_implemented;
+
   file.stat_info = st;
   file.fd = -1;
 
-  if (!sparse_select_optab (&file)
-      || !tar_sparse_init (&file))
-    return dump_status_not_implemented;
-
   rc = tar_sparse_decode_header (&file);
-  skip_file (file.stat_info->archive_file_size);
+  skip_file (file.stat_info->archive_file_size - file.dumped_size);
   return (tar_sparse_done (&file) && rc) ? dump_status_ok : dump_status_short;
 }
 
 
-static char diff_buffer[BLOCKSIZE];
-
 static bool
 check_sparse_region (struct tar_sparse_file *file, off_t beg, off_t end)
 {
@@ -502,11 +481,9 @@ check_sparse_region (struct tar_sparse_file *file, off_t beg, off_t end)
   while (beg < end)
     {
       size_t bytes_read;
-      size_t rdsize = end - beg;
+      size_t rdsize = BLOCKSIZE < end - beg ? BLOCKSIZE : end - beg;
+      char diff_buffer[BLOCKSIZE];
 
-      if (rdsize > BLOCKSIZE)
-	rdsize = BLOCKSIZE;
-      clear_block (diff_buffer);
       bytes_read = safe_read (file->fd, diff_buffer, rdsize);
       if (bytes_read == SAFE_READ_ERROR)
 	{
@@ -517,8 +494,10 @@ check_sparse_region (struct tar_sparse_file *file, off_t beg, off_t end)
 	}
       if (!zero_block_p (diff_buffer, bytes_read))
 	{
+	  char begbuf[INT_BUFSIZE_BOUND (off_t)];
  	  report_difference (file->stat_info,
-			     _("File fragment at %lu is not a hole"), beg);
+			     _("File fragment at %s is not a hole"),
+			     offtostr (beg, begbuf));
 	  return false;
 	}
 
@@ -530,15 +509,18 @@ check_sparse_region (struct tar_sparse_file *file, off_t beg, off_t end)
 static bool
 check_data_region (struct tar_sparse_file *file, size_t i)
 {
-  size_t size_left;
+  off_t size_left;
 
   if (!lseek_or_error (file, file->stat_info->sparse_map[i].offset))
     return false;
   size_left = file->stat_info->sparse_map[i].numbytes;
+  mv_size_left (file->stat_info->archive_file_size - file->dumped_size);
+
   while (size_left > 0)
     {
       size_t bytes_read;
       size_t rdsize = (size_left > BLOCKSIZE) ? BLOCKSIZE : size_left;
+      char diff_buffer[BLOCKSIZE];
 
       union block *blk = find_next_block ();
       if (!blk)
@@ -551,14 +533,15 @@ check_data_region (struct tar_sparse_file *file, size_t i)
       if (bytes_read == SAFE_READ_ERROR)
 	{
           read_diag_details (file->stat_info->orig_file_name,
-			     file->stat_info->sparse_map[i].offset
-	                         + file->stat_info->sparse_map[i].numbytes
-			         - size_left,
+			     (file->stat_info->sparse_map[i].offset
+			      + file->stat_info->sparse_map[i].numbytes
+			      - size_left),
 			     rdsize);
 	  return false;
 	}
       file->dumped_size += bytes_read;
       size_left -= bytes_read;
+      mv_size_left (file->stat_info->archive_file_size - file->dumped_size);
       if (memcmp (blk->buffer, diff_buffer, rdsize))
 	{
 	  report_difference (file->stat_info, _("Contents differ"));
@@ -576,25 +559,27 @@ sparse_diff_file (int fd, struct tar_stat_info *st)
   size_t i;
   off_t offset = 0;
 
+  if (!tar_sparse_init (&file))
+    return dump_status_not_implemented;
+
   file.stat_info = st;
   file.fd = fd;
-
-  if (!sparse_select_optab (&file)
-      || !tar_sparse_init (&file))
-    return dump_status_not_implemented;
+  file.seekable = true; /* File *must* be seekable for compare to work */
 
   rc = tar_sparse_decode_header (&file);
+  mv_begin_read (st);
   for (i = 0; rc && i < file.stat_info->sparse_map_avail; i++)
     {
       rc = check_sparse_region (&file,
 				offset, file.stat_info->sparse_map[i].offset)
-	&& check_data_region (&file, i);
+	    && check_data_region (&file, i);
       offset = file.stat_info->sparse_map[i].offset
 	        + file.stat_info->sparse_map[i].numbytes;
     }
 
   if (!rc)
     skip_file (file.stat_info->archive_file_size - file.dumped_size);
+  mv_end ();
 
   tar_sparse_done (&file);
   return rc;
@@ -604,18 +589,18 @@ sparse_diff_file (int fd, struct tar_stat_info *st)
 /* Old GNU Format. The sparse file information is stored in the
    oldgnu_header in the following manner:
 
-   The header is marked with type 'S'. Its `size' field contains
+   The header is marked with type 'S'. Its 'size' field contains
    the cumulative size of all non-empty blocks of the file. The
-   actual file size is stored in `realsize' member of oldgnu_header.
+   actual file size is stored in 'realsize' member of oldgnu_header.
 
-   The map of the file is stored in a list of `struct sparse'.
+   The map of the file is stored in a list of 'struct sparse'.
    Each struct contains offset to the block of data and its
    size (both as octal numbers). The first file header contains
    at most 4 such structs (SPARSES_IN_OLDGNU_HEADER). If the map
-   contains more structs, then the field `isextended' of the main
-   header is set to 1 (binary) and the `struct sparse_header'
+   contains more structs, then the field 'isextended' of the main
+   header is set to 1 (binary) and the 'struct sparse_header'
    header follows, containing at most 21 following structs
-   (SPARSES_IN_SPARSE_HEADER). If more structs follow, `isextended'
+   (SPARSES_IN_SPARSE_HEADER). If more structs follow, 'isextended'
    field of the extended header is set and next  next extension header
    follows, etc... */
 
@@ -641,13 +626,14 @@ oldgnu_add_sparse (struct tar_sparse_file *file, struct sparse *s)
   if (s->numbytes[0] == '\0')
     return add_finish;
   sp.offset = OFF_FROM_HEADER (s->offset);
-  sp.numbytes = SIZE_FROM_HEADER (s->numbytes);
-  if (sp.offset < 0
+  sp.numbytes = OFF_FROM_HEADER (s->numbytes);
+  if (sp.offset < 0 || sp.numbytes < 0
+      || INT_ADD_OVERFLOW (sp.offset, sp.numbytes)
       || file->stat_info->stat.st_size < sp.offset + sp.numbytes
       || file->stat_info->archive_file_size < 0)
     return add_fail;
 
-  sparse_add_map (file, &sp);
+  sparse_add_map (file->stat_info, &sp);
   return add_ok;
 }
 
@@ -656,10 +642,10 @@ oldgnu_fixup_header (struct tar_sparse_file *file)
 {
   /* NOTE! st_size was initialized from the header
      which actually contains archived size. The following fixes it */
+  off_t realsize = OFF_FROM_HEADER (current_header->oldgnu_header.realsize);
   file->stat_info->archive_file_size = file->stat_info->stat.st_size;
-  file->stat_info->stat.st_size =
-                OFF_FROM_HEADER (current_header->oldgnu_header.realsize);
-  return true;
+  file->stat_info->stat.st_size = max (0, realsize);
+  return 0 <= realsize;
 }
 
 /* Convert old GNU format sparse data to internal representation */
@@ -669,7 +655,7 @@ oldgnu_get_sparse_info (struct tar_sparse_file *file)
   size_t i;
   union block *h = current_header;
   int ext_p;
-  static enum oldgnu_add_status rc;
+  enum oldgnu_add_status rc;
 
   file->stat_info->sparse_map_avail = 0;
   for (i = 0; i < SPARSES_IN_OLDGNU_HEADER; i++)
@@ -711,8 +697,8 @@ oldgnu_store_sparse_info (struct tar_sparse_file *file, size_t *pindex,
     {
       OFF_TO_CHARS (file->stat_info->sparse_map[*pindex].offset,
 		    sp->offset);
-      SIZE_TO_CHARS (file->stat_info->sparse_map[*pindex].numbytes,
-		     sp->numbytes);
+      OFF_TO_CHARS (file->stat_info->sparse_map[*pindex].numbytes,
+		    sp->numbytes);
     }
 }
 
@@ -747,16 +733,14 @@ oldgnu_dump_header (struct tar_sparse_file *file)
       oldgnu_store_sparse_info (file, &i,
 				blk->sparse_header.sp,
 				SPARSES_IN_SPARSE_HEADER);
-      set_next_block_after (blk);
       if (i < file->stat_info->sparse_map_avail)
 	blk->sparse_header.isextended = 1;
-      else
-	break;
+      set_next_block_after (blk);
     }
   return true;
 }
 
-static struct tar_sparse_optab oldgnu_optab = {
+static struct tar_sparse_optab const oldgnu_optab = {
   NULL,  /* No init function */
   NULL,  /* No done function */
   oldgnu_sparse_member_p,
@@ -782,10 +766,10 @@ star_fixup_header (struct tar_sparse_file *file)
 {
   /* NOTE! st_size was initialized from the header
      which actually contains archived size. The following fixes it */
+  off_t realsize = OFF_FROM_HEADER (current_header->star_in_header.realsize);
   file->stat_info->archive_file_size = file->stat_info->stat.st_size;
-  file->stat_info->stat.st_size =
-            OFF_FROM_HEADER (current_header->star_in_header.realsize);
-  return true;
+  file->stat_info->stat.st_size = max (0, realsize);
+  return 0 <= realsize;
 }
 
 /* Convert STAR format sparse data to internal representation */
@@ -795,7 +779,7 @@ star_get_sparse_info (struct tar_sparse_file *file)
   size_t i;
   union block *h = current_header;
   int ext_p;
-  static enum oldgnu_add_status rc;
+  enum oldgnu_add_status rc = add_ok;
 
   file->stat_info->sparse_map_avail = 0;
 
@@ -825,6 +809,7 @@ star_get_sparse_info (struct tar_sparse_file *file)
       set_next_block_after (h);
       for (i = 0; i < SPARSES_IN_STAR_EXT_HEADER && rc == add_ok; i++)
 	rc = oldgnu_add_sparse (file, &h->star_ext_header.sp[i]);
+      file->dumped_size += BLOCKSIZE;
     }
 
   if (rc == add_fail)
@@ -837,7 +822,7 @@ star_get_sparse_info (struct tar_sparse_file *file)
 }
 
 
-static struct tar_sparse_optab star_optab = {
+static struct tar_sparse_optab const star_optab = {
   NULL,  /* No init function */
   NULL,  /* No done function */
   star_sparse_member_p,
@@ -850,8 +835,12 @@ static struct tar_sparse_optab star_optab = {
 };
 
 
-/* GNU PAX sparse file format. The sparse file map is stored in
-   x header:
+/* GNU PAX sparse file format. There are several versions:
+
+   * 0.0
+
+   The initial version of sparse format used by tar 1.14-1.15.1.
+   The sparse file map is stored in x header:
 
    GNU.sparse.size      Real size of the stored file
    GNU.sparse.numblocks Number of blocks in the sparse map
@@ -859,46 +848,343 @@ static struct tar_sparse_optab star_optab = {
      GNU.sparse.offset    Offset of the next data block
      GNU.sparse.numbytes  Size of the next data block
    end repeat
+
+   This has been reported as conflicting with the POSIX specs. The reason is
+   that offsets and sizes of non-zero data blocks were stored in multiple
+   instances of GNU.sparse.offset/GNU.sparse.numbytes variables, whereas
+   POSIX requires the latest occurrence of the variable to override all
+   previous occurrences.
+
+   To avoid this incompatibility two following versions were introduced.
+
+   * 0.1
+
+   Used by tar 1.15.2 -- 1.15.91 (alpha releases).
+
+   The sparse file map is stored in
+   x header:
+
+   GNU.sparse.size      Real size of the stored file
+   GNU.sparse.numblocks Number of blocks in the sparse map
+   GNU.sparse.map       Map of non-null data chunks. A string consisting
+                       of comma-separated values "offset,size[,offset,size]..."
+
+   The resulting GNU.sparse.map string can be *very* long. While POSIX does not
+   impose any limit on the length of a x header variable, this can confuse some
+   tars.
+
+   * 1.0
+
+   Starting from this version, the exact sparse format version is specified
+   explicitely in the header using the following variables:
+
+   GNU.sparse.major     Major version
+   GNU.sparse.minor     Minor version
+
+   X header keeps the following variables:
+
+   GNU.sparse.name      Real file name of the sparse file
+   GNU.sparse.realsize  Real size of the stored file (corresponds to the old
+                        GNU.sparse.size variable)
+
+   The name field of the ustar header is constructed using the pattern
+   "%d/GNUSparseFile.%p/%f".
+
+   The sparse map itself is stored in the file data block, preceding the actual
+   file data. It consists of a series of octal numbers of arbitrary length,
+   delimited by newlines. The map is padded with nulls to the nearest block
+   boundary.
+
+   The first number gives the number of entries in the map. Following are map
+   entries, each one consisting of two numbers giving the offset and size of
+   the data block it describes.
+
+   The format is designed in such a way that non-posix aware tars and tars not
+   supporting GNU.sparse.* keywords will extract each sparse file in its
+   condensed form with the file map attached and will place it into a separate
+   directory. Then, using a simple program it would be possible to expand the
+   file to its original form even without GNU tar.
+
+   Bu default, v.1.0 archives are created. To use other formats,
+   --sparse-version option is provided. Additionally, v.0.0 can be obtained
+   by deleting GNU.sparse.map from 0.1 format: --sparse-version 0.1
+   --pax-option delete=GNU.sparse.map
 */
 
 static bool
 pax_sparse_member_p (struct tar_sparse_file *file)
 {
-  return file->stat_info->archive_file_size != file->stat_info->stat.st_size;
+  return file->stat_info->sparse_map_avail > 0
+          || file->stat_info->sparse_major > 0;
+}
+
+/* Start a header that uses the effective (shrunken) file size.  */
+static union block *
+pax_start_header (struct tar_stat_info *st)
+{
+  off_t realsize = st->stat.st_size;
+  union block *blk;
+  st->stat.st_size = st->archive_file_size;
+  blk = start_header (st);
+  st->stat.st_size = realsize;
+  return blk;
 }
 
 static bool
-pax_dump_header (struct tar_sparse_file *file)
+pax_dump_header_0 (struct tar_sparse_file *file)
 {
   off_t block_ordinal = current_block_ordinal ();
   union block *blk;
   size_t i;
+  char nbuf[UINTMAX_STRSIZE_BOUND];
+  struct sp_array *map = file->stat_info->sparse_map;
+  char *save_file_name = NULL;
 
   /* Store the real file size */
   xheader_store ("GNU.sparse.size", file->stat_info, NULL);
   xheader_store ("GNU.sparse.numblocks", file->stat_info, NULL);
-  for (i = 0; i < file->stat_info->sparse_map_avail; i++)
+
+  if (xheader_keyword_deleted_p ("GNU.sparse.map")
+      || tar_sparse_minor == 0)
     {
-      xheader_store ("GNU.sparse.offset", file->stat_info, &i);
-      xheader_store ("GNU.sparse.numbytes", file->stat_info, &i);
+      for (i = 0; i < file->stat_info->sparse_map_avail; i++)
+	{
+	  xheader_store ("GNU.sparse.offset", file->stat_info, &i);
+	  xheader_store ("GNU.sparse.numbytes", file->stat_info, &i);
+	}
     }
+  else
+    {
+      xheader_store ("GNU.sparse.name", file->stat_info, NULL);
+      save_file_name = file->stat_info->file_name;
+      file->stat_info->file_name = xheader_format_name (file->stat_info,
+					       "%d/GNUSparseFile.%p/%f", 0);
 
-  blk = start_header (file->stat_info);
-  /* Store the effective (shrunken) file size */
-  OFF_TO_CHARS (file->stat_info->archive_file_size, blk->header.size);
+      xheader_string_begin (&file->stat_info->xhdr);
+      for (i = 0; i < file->stat_info->sparse_map_avail; i++)
+	{
+	  if (i)
+	    xheader_string_add (&file->stat_info->xhdr, ",");
+	  xheader_string_add (&file->stat_info->xhdr,
+			      umaxtostr (map[i].offset, nbuf));
+	  xheader_string_add (&file->stat_info->xhdr, ",");
+	  xheader_string_add (&file->stat_info->xhdr,
+			      umaxtostr (map[i].numbytes, nbuf));
+	}
+      if (!xheader_string_end (&file->stat_info->xhdr,
+			       "GNU.sparse.map"))
+	{
+	  free (file->stat_info->file_name);
+	  file->stat_info->file_name = save_file_name;
+	  return false;
+	}
+    }
+  blk = pax_start_header (file->stat_info);
+  finish_header (file->stat_info, blk, block_ordinal);
+  if (save_file_name)
+    {
+      free (file->stat_info->file_name);
+      file->stat_info->file_name = save_file_name;
+    }
+  return true;
+}
+
+static bool
+pax_dump_header_1 (struct tar_sparse_file *file)
+{
+  off_t block_ordinal = current_block_ordinal ();
+  union block *blk;
+  char *p, *q;
+  size_t i;
+  char nbuf[UINTMAX_STRSIZE_BOUND];
+  off_t size = 0;
+  struct sp_array *map = file->stat_info->sparse_map;
+  char *save_file_name = file->stat_info->file_name;
+
+#define COPY_STRING(b,dst,src) do                \
+ {                                               \
+   char *endp = b->buffer + BLOCKSIZE;           \
+   char const *srcp = src;                       \
+   while (*srcp)                                 \
+     {                                           \
+       if (dst == endp)                          \
+	 {                                       \
+	   set_next_block_after (b);             \
+	   b = find_next_block ();               \
+           dst = b->buffer;                      \
+	   endp = b->buffer + BLOCKSIZE;         \
+	 }                                       \
+       *dst++ = *srcp++;                         \
+     }                                           \
+   } while (0)
+
+  /* Compute stored file size */
+  p = umaxtostr (file->stat_info->sparse_map_avail, nbuf);
+  size += strlen (p) + 1;
+  for (i = 0; i < file->stat_info->sparse_map_avail; i++)
+    {
+      p = umaxtostr (map[i].offset, nbuf);
+      size += strlen (p) + 1;
+      p = umaxtostr (map[i].numbytes, nbuf);
+      size += strlen (p) + 1;
+    }
+  size = (size + BLOCKSIZE - 1) / BLOCKSIZE;
+  file->stat_info->archive_file_size += size * BLOCKSIZE;
+  file->dumped_size += size * BLOCKSIZE;
+
+  /* Store sparse file identification */
+  xheader_store ("GNU.sparse.major", file->stat_info, NULL);
+  xheader_store ("GNU.sparse.minor", file->stat_info, NULL);
+  xheader_store ("GNU.sparse.name", file->stat_info, NULL);
+  xheader_store ("GNU.sparse.realsize", file->stat_info, NULL);
+
+  file->stat_info->file_name =
+    xheader_format_name (file->stat_info, "%d/GNUSparseFile.%p/%f", 0);
+  /* Make sure the created header name is shorter than NAME_FIELD_SIZE: */
+  if (strlen (file->stat_info->file_name) > NAME_FIELD_SIZE)
+    file->stat_info->file_name[NAME_FIELD_SIZE] = 0;
+
+  blk = pax_start_header (file->stat_info);
   finish_header (file->stat_info, blk, block_ordinal);
+  free (file->stat_info->file_name);
+  file->stat_info->file_name = save_file_name;
+
+  blk = find_next_block ();
+  q = blk->buffer;
+  p = umaxtostr (file->stat_info->sparse_map_avail, nbuf);
+  COPY_STRING (blk, q, p);
+  COPY_STRING (blk, q, "\n");
+  for (i = 0; i < file->stat_info->sparse_map_avail; i++)
+    {
+      p = umaxtostr (map[i].offset, nbuf);
+      COPY_STRING (blk, q, p);
+      COPY_STRING (blk, q, "\n");
+      p = umaxtostr (map[i].numbytes, nbuf);
+      COPY_STRING (blk, q, p);
+      COPY_STRING (blk, q, "\n");
+    }
+  memset (q, 0, BLOCKSIZE - (q - blk->buffer));
+  set_next_block_after (blk);
   return true;
 }
 
-static struct tar_sparse_optab pax_optab = {
+static bool
+pax_dump_header (struct tar_sparse_file *file)
+{
+  file->stat_info->sparse_major = tar_sparse_major;
+  file->stat_info->sparse_minor = tar_sparse_minor;
+
+  return (file->stat_info->sparse_major == 0) ?
+           pax_dump_header_0 (file) : pax_dump_header_1 (file);
+}
+
+static bool
+decode_num (uintmax_t *num, char const *arg, uintmax_t maxval)
+{
+  uintmax_t u;
+  char *arg_lim;
+
+  if (!ISDIGIT (*arg))
+    return false;
+
+  errno = 0;
+  u = strtoumax (arg, &arg_lim, 10);
+
+  if (! (u <= maxval && errno != ERANGE) || *arg_lim)
+    return false;
+
+  *num = u;
+  return true;
+}
+
+static bool
+pax_decode_header (struct tar_sparse_file *file)
+{
+  if (file->stat_info->sparse_major > 0)
+    {
+      uintmax_t u;
+      char nbuf[UINTMAX_STRSIZE_BOUND];
+      union block *blk;
+      char *p;
+      size_t i;
+
+#define COPY_BUF(b,buf,src) do                                     \
+ {                                                                 \
+   char *endp = b->buffer + BLOCKSIZE;                             \
+   char *dst = buf;                                                \
+   do                                                              \
+     {                                                             \
+       if (dst == buf + UINTMAX_STRSIZE_BOUND -1)                  \
+         {                                                         \
+           ERROR ((0, 0, _("%s: numeric overflow in sparse archive member"), \
+	          file->stat_info->orig_file_name));               \
+           return false;                                           \
+         }                                                         \
+       if (src == endp)                                            \
+	 {                                                         \
+	   set_next_block_after (b);                               \
+           file->dumped_size += BLOCKSIZE;                         \
+           b = find_next_block ();                                 \
+           src = b->buffer;                                        \
+	   endp = b->buffer + BLOCKSIZE;                           \
+	 }                                                         \
+       *dst = *src++;                                              \
+     }                                                             \
+   while (*dst++ != '\n');                                         \
+   dst[-1] = 0;                                                    \
+ } while (0)
+
+      set_next_block_after (current_header);
+      file->dumped_size += BLOCKSIZE;
+      blk = find_next_block ();
+      p = blk->buffer;
+      COPY_BUF (blk,nbuf,p);
+      if (!decode_num (&u, nbuf, TYPE_MAXIMUM (size_t)))
+	{
+	  ERROR ((0, 0, _("%s: malformed sparse archive member"),
+		  file->stat_info->orig_file_name));
+	  return false;
+	}
+      file->stat_info->sparse_map_size = u;
+      file->stat_info->sparse_map = xcalloc (file->stat_info->sparse_map_size,
+					     sizeof (*file->stat_info->sparse_map));
+      file->stat_info->sparse_map_avail = 0;
+      for (i = 0; i < file->stat_info->sparse_map_size; i++)
+	{
+	  struct sp_array sp;
+
+	  COPY_BUF (blk,nbuf,p);
+	  if (!decode_num (&u, nbuf, TYPE_MAXIMUM (off_t)))
+	    {
+	      ERROR ((0, 0, _("%s: malformed sparse archive member"),
+		      file->stat_info->orig_file_name));
+	      return false;
+	    }
+	  sp.offset = u;
+	  COPY_BUF (blk,nbuf,p);
+	  if (!decode_num (&u, nbuf, TYPE_MAXIMUM (off_t)))
+	    {
+	      ERROR ((0, 0, _("%s: malformed sparse archive member"),
+		      file->stat_info->orig_file_name));
+	      return false;
+	    }
+	  sp.numbytes = u;
+	  sparse_add_map (file->stat_info, &sp);
+	}
+      set_next_block_after (blk);
+    }
+
+  return true;
+}
+
+static struct tar_sparse_optab const pax_optab = {
   NULL,  /* No init function */
   NULL,  /* No done function */
   pax_sparse_member_p,
   pax_dump_header,
-  NULL,  /* No decode_header function */
-  NULL,  /* No fixup_header function */
+  NULL,
+  pax_decode_header,
   NULL,  /* No scan_block function */
   sparse_dump_region,
   sparse_extract_region,
 };
-