X-Git-Url: https://git.dogcows.com/gitweb?a=blobdiff_plain;f=src%2Fsparse.c;h=30bf03157c962c09f51fc8b8be07eb6f287e1000;hb=c7ab8eaba40ef39f7b50cce4cb9228bf4ca09d2a;hp=2f5330df3344d4036f51582dff2e932da6cdd1c9;hpb=15a607fc11d8563fe471924fb6e718ceb9adfce4;p=chaz%2Ftar

diff --git a/src/sparse.c b/src/sparse.c
index 2f5330d..30bf031 100644
--- a/src/sparse.c
+++ b/src/sparse.c
@@ -1,6 +1,6 @@
-/* Functions for dealing with sparse files 
+/* Functions for dealing with sparse files
 
-   Copyright (C) 2003 Free Software Foundation, Inc.
+   Copyright (C) 2003, 2004, 2005 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
@@ -14,13 +14,15 @@
 
    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.  */
+   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
 
-#include "system.h"
+#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
   {
@@ -39,21 +41,57 @@ struct tar_sparse_optab
   bool (*decode_header) (struct tar_sparse_file *);
   bool (*scan_block) (struct tar_sparse_file *, enum sparse_scan_state,
 		      void *);
-  bool (*dump_region) (struct tar_sparse_file *, size_t index);
-  bool (*extract_region) (struct tar_sparse_file *, size_t index);
+  bool (*dump_region) (struct tar_sparse_file *, size_t);
+  bool (*extract_region) (struct tar_sparse_file *, size_t);
 };
 
 struct tar_sparse_file
 {
   int fd;                           /* File descriptor */
-  size_t dumped_size;               /* Number of bytes actually written
+  bool seekable;                    /* Is fd seekable? */
+  off_t offset;                     /* Current offset in fd if seekable==false.
+				       Otherwise unused */
+  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 bool
+dump_zeros (struct tar_sparse_file *file, off_t offset)
+{
+  static char const zero_buf[BLOCKSIZE];
+
+  if (offset < file->offset)
+    {
+      errno = EINVAL;
+      return false;
+    }
+
+  while (file->offset < offset)
+    {
+      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 false;
+	}
+      file->offset += wrbytes;
+    }
+
+  return true;
+}
+
 static bool
 tar_sparse_member_p (struct tar_sparse_file *file)
 {
@@ -65,9 +103,14 @@ 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;
 }
 
@@ -89,18 +132,18 @@ tar_sparse_scan (struct tar_sparse_file *file, enum sparse_scan_state state,
 }
 
 static bool
-tar_sparse_dump_region (struct tar_sparse_file *file, size_t index)
+tar_sparse_dump_region (struct tar_sparse_file *file, size_t i)
 {
   if (file->optab->dump_region)
-    return file->optab->dump_region (file, index);
+    return file->optab->dump_region (file, i);
   return false;
 }
 
 static bool
-tar_sparse_extract_region (struct tar_sparse_file *file, size_t index)
+tar_sparse_extract_region (struct tar_sparse_file *file, size_t i)
 {
   if (file->optab->extract_region)
-    return file->optab->extract_region (file, index);
+    return file->optab->extract_region (file, i);
   return false;
 }
 
@@ -130,9 +173,11 @@ tar_sparse_fixup_header (struct tar_sparse_file *file)
 
 
 static bool
-lseek_or_error (struct tar_sparse_file *file, off_t offset, int whence)
+lseek_or_error (struct tar_sparse_file *file, off_t offset)
 {
-  if (lseek (file->fd, offset, whence) < 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;
@@ -144,7 +189,7 @@ lseek_or_error (struct tar_sparse_file *file, off_t offset, int whence)
    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++)
@@ -152,57 +197,46 @@ 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];
+  struct tar_stat_info *st = file->stat_info;
+  int fd = file->fd;
+  char buffer[BLOCKSIZE];
   size_t count;
-  size_t offset = 0;
+  off_t offset = 0;
   struct sp_array sp = {0, 0};
 
-  if (!lseek_or_error (file, 0, SEEK_SET))
+  if (!lseek_or_error (file, 0))
     return false;
-  clear_block (buffer);
 
-  file->stat_info->sparse_map_size = 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)
+  while ((count = safe_read (fd, buffer, sizeof buffer)) != 0
+	 && count != SAFE_READ_ERROR)
     {
-      /* Analize the block */
+      /* Analyze the block.  */
       if (zero_block_p (buffer, count))
 	{
 	  if (sp.numbytes)
 	    {
-	      sparse_add_map (file, &sp);
+	      sparse_add_map (st, &sp);
 	      sp.numbytes = 0;
 	      if (!tar_sparse_scan (file, scan_block, NULL))
 		return false;
@@ -213,26 +247,25 @@ sparse_scan_file (struct tar_sparse_file *file)
 	  if (sp.numbytes == 0)
 	    sp.offset = offset;
 	  sp.numbytes += count;
-	  file->stat_info->archive_file_size += count;
+	  st->archive_file_size += count;
 	  if (!tar_sparse_scan (file, scan_block, buffer))
 	    return false;
 	}
-      
+
       offset += count;
-      clear_block (buffer);
     }
-      
+
   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)
@@ -255,7 +288,7 @@ sparse_select_optab (struct tar_sparse_file *file)
     case STAR_FORMAT:
       file->optab = &star_optab;
       break;
-	
+
     default:
       return false;
     }
@@ -263,35 +296,35 @@ sparse_select_optab (struct tar_sparse_file *file)
 }
 
 static bool
-sparse_dump_region (struct tar_sparse_file *file, size_t index)
+sparse_dump_region (struct tar_sparse_file *file, size_t i)
 {
   union block *blk;
-  off_t bytes_left = file->stat_info->sparse_map[index].numbytes;
-  
-  if (!lseek_or_error (file, file->stat_info->sparse_map[index].offset,
-		       SEEK_SET))
+  off_t bytes_left = file->stat_info->sparse_map[i].numbytes;
+
+  if (!lseek_or_error (file, file->stat_info->sparse_map[i].offset))
     return false;
 
   while (bytes_left > 0)
     {
       size_t bufsize = (bytes_left > BLOCKSIZE) ? BLOCKSIZE : bytes_left;
-      off_t bytes_read;
-      
+      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 < 0)
+      if (bytes_read == SAFE_READ_ERROR)
 	{
           read_diag_details (file->stat_info->orig_file_name,
-	                     file->stat_info->sparse_map[index].offset
-	                         + file->stat_info->sparse_map[index].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;
+      mv_size_left (file->stat_info->archive_file_size - file->dumped_size);
       set_next_block_after (blk);
     }
 
@@ -299,20 +332,19 @@ sparse_dump_region (struct tar_sparse_file *file, size_t index)
 }
 
 static bool
-sparse_extract_region (struct tar_sparse_file *file, size_t index)
+sparse_extract_region (struct tar_sparse_file *file, size_t i)
 {
   size_t write_size;
-  
-  if (!lseek_or_error (file, file->stat_info->sparse_map[index].offset,
-		       SEEK_SET))
+
+  if (!lseek_or_error (file, file->stat_info->sparse_map[i].offset))
     return false;
 
-  write_size = file->stat_info->sparse_map[index].numbytes;
+  write_size = file->stat_info->sparse_map[i].numbytes;
 
   if (write_size == 0)
     {
       /* Last block of the file is a hole */
-      if (sys_truncate (file->fd))
+      if (file->seekable && sys_truncate (file->fd))
 	truncate_warn (file->stat_info->orig_file_name);
     }
   else while (write_size > 0)
@@ -329,6 +361,8 @@ sparse_extract_region (struct tar_sparse_file *file, size_t index)
       count = full_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)
 	{
 	  write_error_details (file->stat_info->orig_file_name,
@@ -343,18 +377,18 @@ sparse_extract_region (struct tar_sparse_file *file, size_t index)
 
 /* Interface functions */
 enum dump_status
-sparse_dump_file (int fd, struct tar_stat_info *stat)
+sparse_dump_file (int fd, struct tar_stat_info *st)
 {
   bool rc;
   struct tar_sparse_file file;
 
-  file.stat_info = stat;
-  file.fd = fd;
-
-  if (!sparse_select_optab (&file)
-      || !tar_sparse_init (&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 */
+
   rc = sparse_scan_file (&file);
   if (rc && file.optab->dump_region)
     {
@@ -364,60 +398,63 @@ sparse_dump_file (int fd, struct tar_stat_info *stat)
 	{
 	  size_t i;
 
+	  mv_begin (file.stat_info);
 	  for (i = 0; rc && i < file.stat_info->sparse_map_avail; i++)
 	    rc = tar_sparse_dump_region (&file, i);
+	  mv_end ();
 	}
     }
 
-  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 *stat)
+sparse_file_p (struct tar_stat_info *st)
 {
-  return (ST_NBLOCKS (stat->stat)
-	  < (stat->stat.st_size / ST_NBLOCKSIZE
-	     + (stat->stat.st_size % ST_NBLOCKSIZE != 0)));
+  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 *stat)
+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 = stat;
+  file.stat_info = st;
   return tar_sparse_member_p (&file);
 }
 
 bool
-sparse_fixup_header (struct tar_stat_info *stat)
+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 = stat;
+  file.stat_info = st;
   return tar_sparse_fixup_header (&file);
 }
 
 enum dump_status
-sparse_extract_file (int fd, struct tar_stat_info *stat, off_t *size)
+sparse_extract_file (int fd, struct tar_stat_info *st, off_t *size)
 {
   bool rc = true;
   struct tar_sparse_file file;
   size_t i;
-  
-  file.stat_info = stat;
-  file.fd = fd;
 
-  if (!sparse_select_optab (&file)
-      || !tar_sparse_init (&file))
+  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;
+
   rc = tar_sparse_decode_header (&file);
   for (i = 0; rc && i < file.stat_info->sparse_map_avail; i++)
     rc = tar_sparse_extract_region (&file, i);
@@ -426,42 +463,37 @@ sparse_extract_file (int fd, struct tar_stat_info *stat, off_t *size)
 }
 
 enum dump_status
-sparse_skip_file (struct tar_stat_info *stat)
+sparse_skip_file (struct tar_stat_info *st)
 {
   bool rc = true;
   struct tar_sparse_file file;
-  
-  file.stat_info = stat;
-  file.fd = -1;
 
-  if (!sparse_select_optab (&file)
-      || !tar_sparse_init (&file))
+  if (!tar_sparse_init (&file))
     return dump_status_not_implemented;
 
+  file.stat_info = st;
+  file.fd = -1;
+
   rc = tar_sparse_decode_header (&file);
   skip_file (file.stat_info->archive_file_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)
 {
-  if (!lseek_or_error (file, beg, SEEK_SET))
+  if (!lseek_or_error (file, beg))
     return false;
-  
+
   while (beg < end)
     {
       size_t bytes_read;
-      size_t rdsize = end - beg;
-      
-      if (rdsize > BLOCKSIZE)
-	rdsize = BLOCKSIZE;
-      clear_block (diff_buffer);
+      size_t rdsize = BLOCKSIZE < end - beg ? BLOCKSIZE : end - beg;
+      char diff_buffer[BLOCKSIZE];
+
       bytes_read = safe_read (file->fd, diff_buffer, rdsize);
-      if (bytes_read < 0)
+      if (bytes_read == SAFE_READ_ERROR)
 	{
           read_diag_details (file->stat_info->orig_file_name,
 	                     beg,
@@ -470,8 +502,10 @@ 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;
 	}
 
@@ -481,19 +515,21 @@ 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 index)
+check_data_region (struct tar_sparse_file *file, size_t i)
 {
   size_t size_left;
-  
-  if (!lseek_or_error (file, file->stat_info->sparse_map[index].offset,
-		       SEEK_SET))
+
+  if (!lseek_or_error (file, file->stat_info->sparse_map[i].offset))
     return false;
-  size_left = file->stat_info->sparse_map[index].numbytes;
+  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)
 	{
@@ -502,17 +538,18 @@ check_data_region (struct tar_sparse_file *file, size_t index)
 	}
       set_next_block_after (blk);
       bytes_read = safe_read (file->fd, diff_buffer, rdsize);
-      if (bytes_read < 0)
+      if (bytes_read == SAFE_READ_ERROR)
 	{
           read_diag_details (file->stat_info->orig_file_name,
-			     file->stat_info->sparse_map[index].offset
-	                         + file->stat_info->sparse_map[index].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"));
@@ -523,45 +560,47 @@ check_data_region (struct tar_sparse_file *file, size_t index)
 }
 
 bool
-sparse_diff_file (int fd, struct tar_stat_info *stat)
+sparse_diff_file (int fd, struct tar_stat_info *st)
 {
   bool rc = true;
   struct tar_sparse_file file;
   size_t i;
   off_t offset = 0;
-  
-  file.stat_info = stat;
-  file.fd = fd;
 
-  if (!sparse_select_optab (&file)
-      || !tar_sparse_init (&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 compare to work */
+  
   rc = tar_sparse_decode_header (&file);
+  mv_begin (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;
 }
 
-     
+
 /* 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 cumulative size of all non-empty blocks of the file. The
    actual file size is stored in `realsize' member of oldgnu_header.
-   
+
    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
@@ -581,13 +620,13 @@ enum oldgnu_add_status
   };
 
 static bool
-oldgnu_sparse_member_p (struct tar_sparse_file *file_unused)
+oldgnu_sparse_member_p (struct tar_sparse_file *file __attribute__ ((unused)))
 {
   return current_header->header.typeflag == GNUTYPE_SPARSE;
 }
 
 /* Add a sparse item to the sparse file and its obstack */
-static enum oldgnu_add_status 
+static enum oldgnu_add_status
 oldgnu_add_sparse (struct tar_sparse_file *file, struct sparse *s)
 {
   struct sp_array sp;
@@ -601,7 +640,7 @@ oldgnu_add_sparse (struct tar_sparse_file *file, struct sparse *s)
       || 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;
 }
 
@@ -612,7 +651,7 @@ oldgnu_fixup_header (struct tar_sparse_file *file)
      which actually contains archived size. The following fixes it */
   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);
+    OFF_FROM_HEADER (current_header->oldgnu_header.realsize);
   return true;
 }
 
@@ -623,9 +662,9 @@ 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;
-  
-  file->stat_info->sparse_map_size = 0;
+  enum oldgnu_add_status rc;
+
+  file->stat_info->sparse_map_avail = 0;
   for (i = 0; i < SPARSES_IN_OLDGNU_HEADER; i++)
     {
       rc = oldgnu_add_sparse (file, &h->oldgnu_header.sp[i]);
@@ -676,7 +715,7 @@ oldgnu_dump_header (struct tar_sparse_file *file)
   off_t block_ordinal = current_block_ordinal ();
   union block *blk;
   size_t i;
-    
+
   blk = start_header (file->stat_info);
   blk->header.typeflag = GNUTYPE_SPARSE;
   if (file->stat_info->sparse_map_avail > SPARSES_IN_OLDGNU_HEADER)
@@ -693,7 +732,7 @@ oldgnu_dump_header (struct tar_sparse_file *file)
 			    SPARSES_IN_OLDGNU_HEADER);
   blk->oldgnu_header.isextended = i < file->stat_info->sparse_map_avail;
   finish_header (file->stat_info, blk, block_ordinal);
-  
+
   while (i < file->stat_info->sparse_map_avail)
     {
       blk = find_next_block ();
@@ -710,7 +749,7 @@ oldgnu_dump_header (struct tar_sparse_file *file)
   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,
@@ -726,7 +765,7 @@ static struct tar_sparse_optab oldgnu_optab = {
 /* Star */
 
 static bool
-star_sparse_member_p (struct tar_sparse_file *file_unused)
+star_sparse_member_p (struct tar_sparse_file *file __attribute__ ((unused)))
 {
   return current_header->header.typeflag == GNUTYPE_SPARSE;
 }
@@ -749,9 +788,9 @@ 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;
-  
-  file->stat_info->sparse_map_size = 0;
+  enum oldgnu_add_status rc = add_ok;
+
+  file->stat_info->sparse_map_avail = 0;
 
   if (h->star_in_header.prefix[0] == '\0'
       && h->star_in_header.sp[0].offset[10] != '\0')
@@ -791,7 +830,7 @@ 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,
@@ -799,7 +838,7 @@ static struct tar_sparse_optab star_optab = {
   star_fixup_header,
   star_get_sparse_info,
   NULL,  /* No scan_block function */
-  NULL, /* No dump region function */ 
+  NULL, /* No dump region function */
   sparse_extract_region,
 };
 
@@ -809,16 +848,34 @@ static struct tar_sparse_optab star_optab = {
 
    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]..."
+
+   Tar versions 1.14-1.15.1 instead of the latter used:
+   
    repeat numblocks time
      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. However,
+   POSIX requires the latest occurrence of the variable to override all
+   previous occurrences.
+     
+   To avoid this incompatibility new keyword GNU.sparse.map was introduced
+   in tar 1.15.2. Some people might still need the 1.14 way of handling
+   sparse files for the compatibility reasons: it can be achieved by
+   specifying `--pax-option delete=GNU.sparse.map' in the command line.
+
+   See FIXME-1.14-1.15.1-1.20, below.
 */
 
 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;
 }
 
 static bool
@@ -827,16 +884,40 @@ pax_dump_header (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;
+    
   /* 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++)
+
+  /* FIXME-1.14-1.15.1-1.20: See the comment above.
+     Starting with 1.17 this should display a warning about POSIX-incompatible
+     keywords being generated. In 1.20, the true branch of the if block below
+     will be removed and GNU.sparse.map will be marked in xhdr_tab as
+     protected. */
+  
+  if (xheader_keyword_deleted_p ("GNU.sparse.map"))
     {
-      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_string_begin ();
+      for (i = 0; i < file->stat_info->sparse_map_avail; i++)
+	{
+	  if (i)
+	    xheader_string_add (",");
+	  xheader_string_add (umaxtostr (map[i].offset, nbuf));
+	  xheader_string_add (",");
+	  xheader_string_add (umaxtostr (map[i].numbytes, nbuf));
+	}
+      xheader_string_end ("GNU.sparse.map");
     }
-  
   blk = start_header (file->stat_info);
   /* Store the effective (shrunken) file size */
   OFF_TO_CHARS (file->stat_info->archive_file_size, blk->header.size);
@@ -844,7 +925,7 @@ pax_dump_header (struct tar_sparse_file *file)
   return true;
 }
 
-static struct tar_sparse_optab pax_optab = {
+static struct tar_sparse_optab const pax_optab = {
   NULL,  /* No init function */
   NULL,  /* No done function */
   pax_sparse_member_p,
@@ -855,4 +936,3 @@ static struct tar_sparse_optab pax_optab = {
   sparse_dump_region,
   sparse_extract_region,
 };
-