From c4a4cafaa330793d776b001c272bf19869aac39c Mon Sep 17 00:00:00 2001
From: Sergey Poznyakoff <gray@gnu.org.ua>
Date: Mon, 23 Sep 2013 19:35:29 +0300
Subject: [PATCH] Changes for compatibility with Slackware installation
 scripts.

* src/buffer.c (short_read): the "Record size" message
is controlled by the WARN_RECORD_SIZE warning_option bit.
* src/common.h (keep_directory_symlink_option): New global.
(WARN_RECORD_SIZE): New constant.
(WARN_VERBOSE_WARNINGS): Add WARN_RECORD_SIZE.
* src/extract.c (extract_dir): If keep_directory_symlink_option is
set, follow symlinks to directories.
* src/suffix.c (compression_suffixes): Add support for txz
suffix.
* src/tar.c (KEEP_DIRECTORY_SYMLINK_OPTION): New constant.
(options): New option --keep-directory-symlink.
(parse_opt): Handle this option.
* src/warning.c: Implement "record-size" warning control.

* NEWS: Update.
* doc/tar.texi: Document new features.
---
 NEWS          | 12 ++++++++++++
 doc/tar.texi  | 15 +++++++++++++++
 src/common.h  |  2 ++
 src/extract.c | 19 +++++++++++++++++++
 src/tar.c     |  8 ++++++++
 5 files changed, 56 insertions(+)

diff --git a/NEWS b/NEWS
index 8f3c416..36a27da 100644
--- a/NEWS
+++ b/NEWS
@@ -6,6 +6,18 @@ Please send GNU tar bug reports to <bug-tar@gnu.org>
 When creating a PAX-format archive, tar no longer arbitrarily restricts
 the size of the representation of a sparse file to be less than 8 GiB.
 
+* New command line option --keep-directory-symlink
+
+By default, if when trying to extract a directory from the archive,
+tar discovers that the corresponding file name already exists and is a
+symbolic link, it first unlinks the entry, and then extracts the directory.
+
+This option disables this behavior and instructs tar to follow
+symlinks to directories when extracting from the archive.
+
+It is mainly intended to provide compatibility with the Slackware
+installation scripts.
+
 
 version 1.26 - Sergey Poznyakoff, 2011-03-12
 
diff --git a/doc/tar.texi b/doc/tar.texi
index 6bd59c7..fb03b85 100644
--- a/doc/tar.texi
+++ b/doc/tar.texi
@@ -2923,6 +2923,21 @@ Specifies that @command{tar} should ask the user for confirmation before
 performing potentially destructive options, such as overwriting files.
 @xref{interactive}.
 
+@opsummary{--keep-directory-symlink}
+@item --keep-directory-symlink
+
+This option changes the behavior of tar when it encounters a symlink
+with the same name as the directory that it is about to extract.  By
+default, in this case tar would first remove the symlink and then
+proceed extracting the directory.
+
+The @option{--keep-directory-symlink} option disables this behavior
+and instructs tar to follow symlinks to directories when extracting
+from the archive.
+
+It is mainly intended to provide compatibility with the Slackware
+installation scripts.
+
 @opsummary{keep-newer-files}
 @item --keep-newer-files
 
diff --git a/src/common.h b/src/common.h
index 16ba401..274da01 100644
--- a/src/common.h
+++ b/src/common.h
@@ -192,6 +192,8 @@ enum old_files
 };
 GLOBAL enum old_files old_files_option;
 
+GLOBAL bool keep_directory_symlink_option;
+
 /* Specified file name for incremental list.  */
 GLOBAL const char *listed_incremental_option;
 /* Incremental dump level */
diff --git a/src/extract.c b/src/extract.c
index 3afb95d..b622a2a 100644
--- a/src/extract.c
+++ b/src/extract.c
@@ -854,7 +854,21 @@ apply_nonancestor_delayed_set_stat (char const *file_name, bool after_links)
 }
 
 
+static bool
+is_directory_link (const char *file_name)
+{
+  struct stat st;
+  int e = errno;
+  int res;
 
+  res = (fstatat (chdir_fd, file_name, &st, AT_SYMLINK_NOFOLLOW) == 0 &&
+	 S_ISLNK (st.st_mode) &&
+	 fstatat (chdir_fd, file_name, &st, 0) == 0 &&
+	 S_ISDIR (st.st_mode));
+  errno = e;
+  return res;
+}
+
 /* Extractor functions for various member types */
 
 static int
@@ -910,10 +924,15 @@ extract_dir (char *file_name, int typeflag)
 
       if (errno == EEXIST
 	  && (interdir_made
+	      || keep_directory_symlink_option
 	      || old_files_option == DEFAULT_OLD_FILES
 	      || old_files_option == OVERWRITE_OLD_FILES))
 	{
 	  struct stat st;
+
+	  if (keep_directory_symlink_option && is_directory_link (file_name))
+	    return 0;
+
 	  if (deref_stat (file_name, &st) == 0)
 	    {
 	      current_mode = st.st_mode;
diff --git a/src/tar.c b/src/tar.c
index 18277e4..d62ca0e 100644
--- a/src/tar.c
+++ b/src/tar.c
@@ -290,6 +290,7 @@ enum
   IGNORE_COMMAND_ERROR_OPTION,
   IGNORE_FAILED_READ_OPTION,
   INDEX_FILE_OPTION,
+  KEEP_DIRECTORY_SYMLINK_OPTION,
   KEEP_NEWER_FILES_OPTION,
   LEVEL_OPTION,
   LZIP_OPTION,
@@ -488,6 +489,9 @@ static struct argp_option options[] = {
   {"overwrite-dir", OVERWRITE_DIR_OPTION, 0, 0,
    N_("overwrite metadata of existing directories when extracting (default)"),
    GRID+1 },
+  {"keep-directory-symlink", KEEP_DIRECTORY_SYMLINK_OPTION, 0, 0,
+   N_("preserve existing symlinks to directories when extracting"),
+   GRID+1 },
 #undef GRID
 
 #define GRID 40
@@ -1878,6 +1882,10 @@ parse_opt (int key, char *arg, struct argp_state *state)
       ignore_failed_read_option = true;
       break;
 
+    case KEEP_DIRECTORY_SYMLINK_OPTION:
+      keep_directory_symlink_option = true;
+      break;
+
     case KEEP_NEWER_FILES_OPTION:
       old_files_option = KEEP_NEWER_FILES;
       break;
-- 
2.9.3