adding GNUNET_DISK_file_backup function; fixing #2646

git-svn-id: https://gnunet.org/svn/gnunet@25333 140774ce-b5e7-0310-ab8b-a85725594a96

3 files changed, 127 insertions, 89 deletions

diff --git a/src/include/gnunet_disk_lib.h b/src/include/gnunet_disk_lib.h
index 9d4cd1820b..dd42f9e91f 100644
--- a/src/include/gnunet_disk_lib.h
+++ b/src/include/gnunet_disk_lib.h
@@ -1,6 +1,6 @@
 /*
      This file is part of GNUnet.
-     (C) 2001, 2002, 2003, 2004, 2005, 2006, 2009 Christian Grothoff (and other contributing authors)
+     (C) 2001-2012 Christian Grothoff (and other contributing authors)
 
      GNUnet is free software; you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published
@@ -17,10 +17,10 @@
      Free Software Foundation, Inc., 59 Temple Place - Suite 330,
      Boston, MA 02111-1307, USA.
 */
-
 /**
  * @file include/gnunet_disk_lib.h
  * @brief disk IO apis
+ * @author Christian Grothoff
  */
 #ifndef GNUNET_DISK_LIB_H
 #define GNUNET_DISK_LIB_H
@@ -85,8 +85,7 @@ struct GNUNET_DISK_FileHandle
    */
   int fd;
 
-#endif                          /*
-                                 */
+#endif
 };
 
 
@@ -113,39 +112,39 @@ extern "C"
 enum GNUNET_DISK_OpenFlags
 {
 
-    /**
-     * Open the file for reading
-     */
+  /**
+   * Open the file for reading
+   */
   GNUNET_DISK_OPEN_READ = 1,
 
-    /**
-     * Open the file for writing
-     */
+  /**
+   * Open the file for writing
+   */
   GNUNET_DISK_OPEN_WRITE = 2,
 
-    /**
-     * Open the file for both reading and writing
-     */
+  /**
+   * Open the file for both reading and writing
+   */
   GNUNET_DISK_OPEN_READWRITE = 3,
 
-    /**
-     * Fail if file already exists
-     */
+  /**
+   * Fail if file already exists
+   */
   GNUNET_DISK_OPEN_FAILIFEXISTS = 4,
 
-    /**
-     * Truncate file if it exists
-     */
+  /**
+   * Truncate file if it exists
+   */
   GNUNET_DISK_OPEN_TRUNCATE = 8,
 
-    /**
-     * Create file if it doesn't exist
-     */
+  /**
+   * Create file if it doesn't exist
+   */
   GNUNET_DISK_OPEN_CREATE = 16,
 
-    /**
-     * Append to the file
-     */
+  /**
+   * Append to the file
+   */
   GNUNET_DISK_OPEN_APPEND = 32
 };
 
@@ -154,18 +153,19 @@ enum GNUNET_DISK_OpenFlags
  */
 enum GNUNET_DISK_MapType
 {
-    /**
-     * Read-only memory map.
-     */
+  /**
+   * Read-only memory map.
+   */
   GNUNET_DISK_MAP_TYPE_READ = 1,
-
-    /**
-     * Write-able memory map.
-     */
+  
+  /**
+   * Write-able memory map.
+   */
   GNUNET_DISK_MAP_TYPE_WRITE = 2,
-    /**
-     * Read-write memory map.
-     */
+
+  /**
+   * Read-write memory map.
+   */
   GNUNET_DISK_MAP_TYPE_READWRITE = 3
 };
 
@@ -175,54 +175,54 @@ enum GNUNET_DISK_MapType
  */
 enum GNUNET_DISK_AccessPermissions
 {
-    /**
-     * Nobody is allowed to do anything to the file.
-     */
+  /**
+   * Nobody is allowed to do anything to the file.
+   */
   GNUNET_DISK_PERM_NONE = 0,
 
-    /**
-     * Owner can read.
-     */
+  /**
+   * Owner can read.
+   */
   GNUNET_DISK_PERM_USER_READ = 1,
 
-    /**
-     * Owner can write.
-     */
+  /**
+   * Owner can write.
+   */
   GNUNET_DISK_PERM_USER_WRITE = 2,
 
-    /**
-     * Owner can execute.
-     */
+  /**
+   * Owner can execute.
+   */
   GNUNET_DISK_PERM_USER_EXEC = 4,
 
-    /**
-     * Group can read.
-     */
+  /**
+   * Group can read.
+   */
   GNUNET_DISK_PERM_GROUP_READ = 8,
 
-    /**
-     * Group can write.
-     */
+  /**
+   * Group can write.
+   */
   GNUNET_DISK_PERM_GROUP_WRITE = 16,
 
-    /**
-     * Group can execute.
-     */
+  /**
+   * Group can execute.
+   */
   GNUNET_DISK_PERM_GROUP_EXEC = 32,
 
-    /**
-     * Everybody can read.
-     */
+  /**
+   * Everybody can read.
+   */
   GNUNET_DISK_PERM_OTHER_READ = 64,
 
-    /**
-     * Everybody can write.
-     */
+  /**
+   * Everybody can write.
+   */
   GNUNET_DISK_PERM_OTHER_WRITE = 128,
 
-    /**
-     * Everybody can execute.
-     */
+  /**
+   * Everybody can execute.
+   */
   GNUNET_DISK_PERM_OTHER_EXEC = 256
 };
 
@@ -233,19 +233,19 @@ enum GNUNET_DISK_AccessPermissions
  */
 enum GNUNET_DISK_Seek
 {
-    /**
-     * Seek an absolute position (from the start of the file).
-     */
+  /**
+   * Seek an absolute position (from the start of the file).
+   */
   GNUNET_DISK_SEEK_SET = 0,
 
-    /**
-     * Seek a relative position (from the current offset).
-     */
+  /**
+   * Seek a relative position (from the current offset).
+   */
   GNUNET_DISK_SEEK_CUR = 1,
 
-    /**
-     * Seek an absolute position from the end of the file.
-     */
+  /**
+   * Seek an absolute position from the end of the file.
+   */
   GNUNET_DISK_SEEK_END = 2
 };
 
@@ -255,14 +255,14 @@ enum GNUNET_DISK_Seek
  */
 enum GNUNET_DISK_PipeEnd
 {
-    /**
-     * The reading-end of a pipe.
-     */
+  /**
+   * The reading-end of a pipe.
+   */
   GNUNET_DISK_PIPE_END_READ = 0,
 
-    /**
-     * The writing-end of a pipe.
-     */
+  /**
+   * The writing-end of a pipe.
+   */
   GNUNET_DISK_PIPE_END_WRITE = 1
 };
 
@@ -301,6 +301,17 @@ GNUNET_DISK_file_test (const char *fil);
 
 
 /**
+ * Move a file out of the way (create a backup) by
+ * renaming it to "orig.NUM~" where NUM is the smallest
+ * number that is not used yet.
+ *
+ * @param fil name of the file to back up
+ */
+void
+GNUNET_DISK_file_backup (const char *fil);
+
+
+/**
  * Move the read/write pointer in a file
  * @param h handle of an open file
  * @param offset position to move to
diff --git a/src/util/crypto_rsa.c b/src/util/crypto_rsa.c
index ff99ecf0b8..cd9a33f614 100644
--- a/src/util/crypto_rsa.c
+++ b/src/util/crypto_rsa.c
@@ -641,12 +641,11 @@ try_read_key (const char *filename)
   if (fs > UINT16_MAX)
   {
     LOG (GNUNET_ERROR_TYPE_ERROR,
-         _("File `%s' does not contain a valid private key (too long, %llu bytes).  Deleting it.\n"),	
+         _("File `%s' does not contain a valid private key (too long, %llu bytes).  Renaming it.\n"),	
          filename,
 	 (unsigned long long) fs);
     GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fd));
-    if (0 != UNLINK (filename))    
-      LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "unlink", filename);
+    GNUNET_DISK_file_backup (filename);
     return NULL;
   }
 
@@ -662,8 +661,7 @@ try_read_key (const char *filename)
          filename,
 	 (unsigned long long) fs);
     GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fd));
-    if (0 != UNLINK (filename))    
-      LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "unlink", filename);
+    GNUNET_DISK_file_backup (filename);
     GNUNET_free (enc);
     return NULL;
   }
@@ -857,10 +855,7 @@ GNUNET_CRYPTO_rsa_key_create_from_file (const char *filename)
     LOG (GNUNET_ERROR_TYPE_ERROR,
          _("File `%s' does not contain a valid private key.  Deleting it.\n"),
          filename);
-    if (0 != UNLINK (filename))
-    {
-      LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "unlink", filename);
-    }
+    GNUNET_DISK_file_backup (filename);
   }
   GNUNET_free (enc);
   if (GNUNET_YES !=
diff --git a/src/util/disk.c b/src/util/disk.c
index 8d1fed897e..8cb69d2a4e 100644
--- a/src/util/disk.c
+++ b/src/util/disk.c
@@ -495,6 +495,38 @@ GNUNET_DISK_mkdtemp (const char *t)
 
 
 /**
+ * Move a file out of the way (create a backup) by
+ * renaming it to "orig.NUM~" where NUM is the smallest
+ * number that is not used yet.
+ *
+ * @param fil name of the file to back up
+ */
+void
+GNUNET_DISK_file_backup (const char *fil)
+{
+  size_t slen;
+  char *target;
+  unsigned int num;
+
+  slen = strlen (fil) + 20;
+  target = GNUNET_malloc (slen);
+  num = 0;
+  do
+  {
+    GNUNET_snprintf (target, slen,
+		     "%s.%u~",
+		     fil,
+		     num++);
+  } while (0 == access (target, F_OK));
+  if (0 != rename (fil, target))
+    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR,
+			      "rename",
+			      fil);
+  GNUNET_free (target);  
+}
+
+
+/**
  * Create an (empty) temporary file on disk.  If the given name is not
  * an absolute path, the current 'TMPDIR' will be prepended.  In any case,
  * 6 random characters will be appended to the name to create a unique