Bug#576876: tar: no progress made in case of existing symlink

[Michael Banck]

tags 576876 +patch
thanks

On Sat, Apr 17, 2010 at 12:36:23AM +0200, Michael Banck wrote:
> as a data point, 1.22-2 is still alright, 1.23-1 is the problem.

This is a trivial recipe to reproduce it:

$ ln -s foo bar
$ tar cf bar.tar bar 
$ cat bar.tar | tar -xkf - 
<hang>

I have attached an interdiff which fixes this, I might NMU this during
the BSP this weekend. 


Michael

diff -u tar-1.23/debian/changelog tar-1.23/debian/changelog
--- tar-1.23/debian/changelog
+++ tar-1.23/debian/changelog
@@ -1,3 +1,12 @@
+tar (1.23-2.1) UNRELEASED; urgency=low
+
+  * Non-maintainer upload.
+  * src/extract.c: Apply upstream git commit b60e56fd which fixes a dead loop
+    on extracting existing symlinks with the -k option, closes: #577978,
+    #576876.
+
+ -- Michael Banck <mba...@debian.org>  Tue, 13 Jul 2010 19:39:40 +0200
+
 tar (1.23-2) unstable; urgency=low
 
   * use xz when lzma is called for, and stop suggesting both lzma since it's
only in patch2:
unchanged:
--- tar-1.23.orig/src/extract.c
+++ tar-1.23/src/extract.c
@@ -888,12 +888,22 @@
   struct stat st;
 
   while ((fd = open (file_name, O_WRONLY | O_CREAT | O_EXCL, 0)) < 0)
-    if (! maybe_recoverable (file_name, interdir_made))
-      break;
+    {
+      switch (maybe_recoverable (file_name, interdir_made))
+       {
+       case RECOVER_OK:
+         continue;
+         
+       case RECOVER_SKIP:
+         return 0;
+         
+       case RECOVER_NO:
+         open_error (file_name);
+         return -1;
+       }
+      }
 
-  if (fd < 0)
-    open_error (file_name);
-  else if (fstat (fd, &st) != 0)
+  if (fstat (fd, &st) != 0)
     {
       stat_error (file_name);
       close (fd);
@@ -956,7 +966,8 @@
 {
   int interdir_made = 0;
   char const *link_name;
-
+  int rc;
+  
   link_name = current_stat_info.link_name;
   
   if (! absolute_names_option && contains_dot_dot (link_name))
@@ -996,8 +1007,10 @@
 
       errno = e;
     }
-  while (maybe_recoverable (file_name, &interdir_made));
+  while ((rc = maybe_recoverable (file_name, &interdir_made)) == RECOVER_OK);
 
+  if (rc == RECOVER_SKIP)
+    return 0;
   if (!(incremental_option && errno == EEXIST))
     {
       link_error (link_name, file_name);
@@ -1010,7 +1023,6 @@
 extract_symlink (char *file_name, int typeflag)
 {
 #ifdef HAVE_SYMLINK
-  int status;
   int interdir_made = 0;
 
   if (! absolute_names_option
@@ -1018,15 +1030,22 @@
          || contains_dot_dot (current_stat_info.link_name)))
     return create_placeholder_file (file_name, true, &interdir_made);
 
-  while ((status = symlink (current_stat_info.link_name, file_name)))
-    if (!maybe_recoverable (file_name, &interdir_made))
-      break;
-
-  if (status == 0)
-    set_stat (file_name, &current_stat_info, NULL, 0, 0, SYMTYPE);
-  else
-    symlink_error (current_stat_info.link_name, file_name);
-  return status;
+  while (symlink (current_stat_info.link_name, file_name))
+    switch (maybe_recoverable (file_name, &interdir_made))
+      {
+      case RECOVER_OK:
+       continue;
+       
+      case RECOVER_SKIP:
+       return 0;
+       
+      case RECOVER_NO:
+       symlink_error (current_stat_info.link_name, file_name);
+       return -1;
+      }
+  
+  set_stat (file_name, &current_stat_info, NULL, 0, 0, SYMTYPE);
+  return 0;
 
 #else
   static int warned_once;
@@ -1052,16 +1071,23 @@
   mode_t invert_permissions =
     0 < same_owner_option ? mode & (S_IRWXG | S_IRWXO) : 0;
 
-  do
-    status = mknod (file_name, mode ^ invert_permissions,
-                   current_stat_info.stat.st_rdev);
-  while (status && maybe_recoverable (file_name, &interdir_made));
+  while (mknod (file_name, mode ^ invert_permissions,
+               current_stat_info.stat.st_rdev))
+    switch (maybe_recoverable (file_name, &interdir_made))
+      {
+      case RECOVER_OK:
+       continue;
+       
+      case RECOVER_SKIP:
+       return 0;
+       
+      case RECOVER_NO:
+       mknod_error (file_name);
+       return -1;
+      }
 
-  if (status != 0)
-    mknod_error (file_name);
-  else
-    set_stat (file_name, &current_stat_info, NULL, invert_permissions,
-             ARCHIVED_PERMSTATUS, typeflag);
+  set_stat (file_name, &current_stat_info, NULL, invert_permissions,
+           ARCHIVED_PERMSTATUS, typeflag);
   return status;
 }
 #endif
@@ -1077,15 +1103,22 @@
     0 < same_owner_option ? mode & (S_IRWXG | S_IRWXO) : 0;
 
   while ((status = mkfifo (file_name, mode)) != 0)
-    if (!maybe_recoverable (file_name, &interdir_made))
-      break;
+    switch (maybe_recoverable (file_name, &interdir_made))
+      {
+      case RECOVER_OK:
+       continue;
+       
+      case RECOVER_SKIP:
+       return 0;
+       
+      case RECOVER_NO:
+       mkfifo_error (file_name);
+       return -1;
+      }
 
-  if (status == 0)
-    set_stat (file_name, &current_stat_info, NULL, invert_permissions,
-             ARCHIVED_PERMSTATUS, typeflag);
-  else
-    mkfifo_error (file_name);
-  return status;
+  set_stat (file_name, &current_stat_info, NULL, invert_permissions,
+           ARCHIVED_PERMSTATUS, typeflag);
+  return 0;
 }
 #endif