[Pkg-gnupg-commit] [gnupg2] 119/159: kbx: New function keybox_file_rename to replace rename.

[Daniel Kahn Gillmor]

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dkg pushed a commit to branch master
in repository gnupg2.

commit 8241ed59d05e06252647b26477ed5c2f84895a26
Author: Werner Koch <wk at gnupg.org>
Date:   Thu Jan 14 16:50:15 2016 +0100

    kbx: New function keybox_file_rename to replace rename.
    
    * kbx/keybox-util.c: Include windows.h.
    (keybox_file_rename): New.
    * kbx/keybox-update.c (rename_tmp_file): Replace remove+rename by
    keybox_file_rename.
    * g10/keyring.c (rename_tmp_file): Ditto.
    
    Signed-off-by: Werner Koch <wk at gnupg.org>
---
 g10/keyring.c       | 23 +++++--------------
 kbx/keybox-update.c | 17 +++++---------
 kbx/keybox-util.c   | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 kbx/keybox.h        |  1 +
 4 files changed, 76 insertions(+), 30 deletions(-)

diff --git a/g10/keyring.c b/g10/keyring.c
index 535dd2b..7ae50a3 100644
--- a/g10/keyring.c
+++ b/g10/keyring.c
@@ -1337,32 +1337,19 @@ rename_tmp_file (const char *bakfname, const char *tmpfname, const char *fname)
   iobuf_ioctl (NULL, IOBUF_IOCTL_INVALIDATE_CACHE, 0, (char*)fname );
 
   /* First make a backup file. */
-#if defined(HAVE_DOSISH_SYSTEM) || defined(__riscos__)
-  gnupg_remove (bakfname);
-#endif
-  if (rename (fname, bakfname) )
-    {
-      rc = gpg_error_from_syserror ();
-      log_error ("renaming '%s' to '%s' failed: %s\n",
-                 fname, bakfname, strerror(errno) );
-      return rc;
-    }
+  rc = keybox_file_rename (fname, bakfname);
+  if (rc)
+    goto fail;
 
   /* then rename the file */
-#if defined(HAVE_DOSISH_SYSTEM) || defined(__riscos__)
-  gnupg_remove( fname );
-#endif
-  if (rename (tmpfname, fname) )
+  rc = keybox_file_rename (tmpfname, fname);
+  if (rc)
     {
-      rc = gpg_error_from_syserror ();
-      log_error (_("renaming '%s' to '%s' failed: %s\n"),
-                 tmpfname, fname, strerror(errno) );
       register_secured_file (fname);
       goto fail;
     }
 
   /* Now make sure the file has the same permissions as the original */
-
 #ifndef HAVE_DOSISH_SYSTEM
   {
     struct stat statbuf;
diff --git a/kbx/keybox-update.c b/kbx/keybox-update.c
index eebcfca..ff65904 100644
--- a/kbx/keybox-update.c
+++ b/kbx/keybox-update.c
@@ -119,22 +119,15 @@ rename_tmp_file (const char *bakfname, const char *tmpfname,
   /* First make a backup file except for secret keyboxes. */
   if (!secret)
     {
-#if defined(HAVE_DOSISH_SYSTEM) || defined(__riscos__)
-      gnupg_remove (bakfname);
-#endif
-      if (rename (fname, bakfname) )
-        {
-          return gpg_error_from_syserror ();
-	}
+      rc = keybox_file_rename (fname, bakfname);
+      if (rc)
+        return rc;
     }
 
   /* Then rename the file. */
-#if defined(HAVE_DOSISH_SYSTEM) || defined(__riscos__)
-  gnupg_remove (fname);
-#endif
-  if (rename (tmpfname, fname) )
+  rc = keybox_file_rename (tmpfname, fname);
+  if (rc)
     {
-      rc = gpg_error_from_syserror ();
       if (secret)
         {
 /*            log_info ("WARNING: 2 files with confidential" */
diff --git a/kbx/keybox-util.c b/kbx/keybox-util.c
index f7efd1a..740ea73 100644
--- a/kbx/keybox-util.c
+++ b/kbx/keybox-util.c
@@ -21,6 +21,10 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#ifdef  HAVE_DOSISH_SYSTEM
+# define WIN32_LEAN_AND_MEAN  /* We only need the OS core stuff.  */
+# include <windows.h>
+#endif
 
 #include "keybox-defs.h"
 
@@ -141,3 +145,64 @@ keybox_tmp_names (const char *filename, int for_keyring,
   *r_tmpname = tmp_name;
   return 0;
 }
+
+
+/* Wrapper for rename(2) to handle Windows peculiarities.  */
+gpg_error_t
+keybox_file_rename (const char *oldname, const char *newname)
+{
+  gpg_error_t err = 0;
+
+#ifdef HAVE_DOSISH_SYSTEM
+  int wtime = 0;
+
+  gnupg_remove (newname);
+ again:
+  if (rename (oldname, newname))
+    {
+      if (GetLastError () == ERROR_SHARING_VIOLATION)
+        {
+          /* Another process has the file open.  We do not use a lock
+           * for read but instead we wait until the other process has
+           * closed the file.  This may take long but that would also
+           * be the case with a dotlock approach for read and write.
+           * Note that we don't need this on Unix due to the inode
+           * concept.
+           *
+           * So let's wait until the rename has worked.  We use the
+           * same retry intervals as used by dotlock.c, namely 50ms,
+           * 100ms, 200ms, 400ms, 800ms, 2s, 4s and 8s.  */
+          if (!wtime)
+            wtime = 50;
+          else if (wtime < 800)
+            wtime *= 2;
+          else if (wtime == 800)
+            wtime = 2000;
+          else if (wtime < 8000)
+            wtime *= 2;
+
+          if (wtime >= 800)
+            log_info ("waiting for file '%s' to become accessible ...\n",
+                      oldname);
+
+          Sleep (wtime);
+          goto again;
+        }
+      err = gpg_error_from_syserror ();
+    }
+
+#else /* Unix */
+
+#ifdef __riscos__
+  gnupg_remove (newname);
+#endif
+  if (rename (oldname, newname) )
+    err = gpg_error_from_syserror ();
+
+#endif /* Unix */
+
+  if (err)
+    log_error ("renaming '%s' to '%s' failed: %s\n",
+               oldname, newname, gpg_strerror (err));
+  return err;
+}
diff --git a/kbx/keybox.h b/kbx/keybox.h
index 4d556c5..bfc3586 100644
--- a/kbx/keybox.h
+++ b/kbx/keybox.h
@@ -134,6 +134,7 @@ void keybox_set_malloc_hooks ( void *(*new_alloc_func)(size_t n),
 
 gpg_error_t keybox_tmp_names (const char *filename, int for_keyring,
                               char **r_bakname, char **r_tmpname);
+gpg_error_t keybox_file_rename (const char *oldname, const char *newname);
 
 
 #ifdef __cplusplus

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