gpg: Take care to use pubring.kbx if it has ever been used.

* kbx/keybox-defs.h (struct keybox_handle): Add field for_openpgp.
* kbx/keybox-file.c (_keybox_write_header_blob): Set openpgp header
flag.
* kbx/keybox-blob.c (_keybox_update_header_blob): Add arg for_openpgp
and set header flag.
* kbx/keybox-init.c (keybox_new): Rename to do_keybox_new, make static
and add arg for_openpgp.
(keybox_new_openpgp, keybox_new_x509): New.  Use them instead of the
former keybox_new.
* kbx/keybox-update.c (blob_filecopy): Add arg for_openpgp and set the
openpgp header flags.

* g10/keydb.c (rt_from_file): New.  Factored out and extended from
keydb_add_resource.
(keydb_add_resource): Switch to the kbx file if it has the openpgp
flag set.

* kbx/keybox-dump.c (dump_header_blob): Print header flags.
--

The problem was reported by dkg on gnupg-devel (2014-10-07):

  I just discovered a new problem, though, which will affect people on
  systems that have gpg and gpg2 coinstalled:

   0) create a new keyring with gpg2, and use it exclusively with gpg2
  for a while.
   1) somehow (accidentally?) use gpg (1.4.x) again -- this creates
  ~/.gnupg/pubring.gpg
   2) future runs of gpg2 now only look at pubring.gpg and ignore
  pubring.kbx -- the keys you had accumulated in the keybox are no
  longer listed in the output of gpg2 --list-keys

Note that gpgsm has always used pubring.kbx and thus this file might
already be there but without gpg ever inserted a key.  The new flag in
the KBX header gives us an indication whether a KBX file has ever been
written by gpg >= 2.1.  If that is the case we will use it instead of
the default pubring.gpg.

Signed-off-by: Werner Koch <wk@gnupg.org>

7 files changed, 86 insertions, 27 deletions

diff --git a/kbx/keybox-blob.c b/kbx/keybox-blob.c
index f7abb6ccd..35ce3e360 100644
--- a/kbx/keybox-blob.c
+++ b/kbx/keybox-blob.c
@@ -42,8 +42,9 @@
    - u32  Length of this blob
    - byte Blob type (1)
    - byte Version number (1)
-   - byte RFU
-   - byte RFU
+   - u16  Header flags
+          bit 0 - RFU
+          bit 1 - Is being or has been used for OpenPGP blobs
    - b4   Magic 'KBXf'
    - u32  RFU
    - u32  file_created_at
@@ -1028,7 +1029,7 @@ _keybox_get_blob_fileoffset (KEYBOXBLOB blob)
 
 
 void
-_keybox_update_header_blob (KEYBOXBLOB blob)
+_keybox_update_header_blob (KEYBOXBLOB blob, int for_openpgp)
 {
   if (blob->bloblen >= 32 && blob->blob[4] == BLOBTYPE_HEADER)
     {
@@ -1039,5 +1040,8 @@ _keybox_update_header_blob (KEYBOXBLOB blob)
       blob->blob[20+1] = (val >> 16);
       blob->blob[20+2] = (val >>  8);
       blob->blob[20+3] = (val      );
+
+      if (for_openpgp)
+        blob->blob[7] |= 0x02;  /* OpenPGP data may be available.  */
     }
 }
diff --git a/kbx/keybox-defs.h b/kbx/keybox-defs.h
index 7bbcf83cf..415a3efff 100644
--- a/kbx/keybox-defs.h
+++ b/kbx/keybox-defs.h
@@ -101,6 +101,7 @@ struct keybox_handle {
   int eof;
   int error;
   int ephemeral;
+  int for_openpgp;        /* Used by gpg.  */
   struct keybox_found_s found;
   struct keybox_found_s saved_found;
   struct {
@@ -176,7 +177,7 @@ int  _keybox_new_blob (KEYBOXBLOB *r_blob,
 void _keybox_release_blob (KEYBOXBLOB blob);
 const unsigned char *_keybox_get_blob_image (KEYBOXBLOB blob, size_t *n);
 off_t _keybox_get_blob_fileoffset (KEYBOXBLOB blob);
-void _keybox_update_header_blob (KEYBOXBLOB blob);
+void _keybox_update_header_blob (KEYBOXBLOB blob, int for_openpgp);
 
 /*-- keybox-openpgp.c --*/
 gpg_error_t _keybox_parse_openpgp (const unsigned char *image, size_t imagelen,
diff --git a/kbx/keybox-dump.c b/kbx/keybox-dump.c
index af9052d69..bfe7b4899 100644
--- a/kbx/keybox-dump.c
+++ b/kbx/keybox-dump.c
@@ -141,6 +141,25 @@ dump_header_blob (const byte *buffer, size_t length, FILE *fp)
       return -1;
     }
   fprintf (fp, "Version: %d\n", buffer[5]);
+
+  n = get16 (buffer + 6);
+  fprintf( fp, "Flags:   %04lX", n);
+  if (n)
+    {
+      int any = 0;
+
+      fputs (" (", fp);
+      if ((n & 2))
+        {
+          if (any)
+            putc (',', fp);
+          fputs ("openpgp", fp);
+          any++;
+        }
+      putc (')', fp);
+    }
+  putc ('\n', fp);
+
   if ( memcmp (buffer+8, "KBXf", 4))
     fprintf (fp, "[Error: invalid magic number]\n");
 
diff --git a/kbx/keybox-file.c b/kbx/keybox-file.c
index f72099348..def896bca 100644
--- a/kbx/keybox-file.c
+++ b/kbx/keybox-file.c
@@ -132,7 +132,7 @@ _keybox_write_blob (KEYBOXBLOB blob, FILE *fp)
 
 /* Write a fresh header type blob. */
 int
-_keybox_write_header_blob (FILE *fp)
+_keybox_write_header_blob (FILE *fp, int for_openpgp)
 {
   unsigned char image[32];
   u32 val;
@@ -143,6 +143,8 @@ _keybox_write_header_blob (FILE *fp)
 
   image[4] = BLOBTYPE_HEADER;
   image[5] = 1; /* Version */
+  if (for_openpgp)
+    image[7] = 0x02; /* OpenPGP data may be available.  */
 
   memcpy (image+8, "KBXf", 4);
   val = time (NULL);
diff --git a/kbx/keybox-init.c b/kbx/keybox-init.c
index 8ae3ec315..0d4800e12 100644
--- a/kbx/keybox-init.c
+++ b/kbx/keybox-init.c
@@ -77,15 +77,10 @@ keybox_is_writable (void *token)
 
 
 
-/* Create a new handle for the resource associated with TOKEN.  SECRET
-   is just a cross-check.
-
-   The returned handle must be released using keybox_release (). */
-KEYBOX_HANDLE
-keybox_new (void *token, int secret)
+static KEYBOX_HANDLE
+do_keybox_new (KB_NAME resource, int secret, int for_openpgp)
 {
   KEYBOX_HANDLE hd;
-  KB_NAME resource = token;
   int idx;
 
   assert (resource && !resource->secret == !secret);
@@ -94,6 +89,7 @@ keybox_new (void *token, int secret)
     {
       hd->kb = resource;
       hd->secret = !!secret;
+      hd->for_openpgp = for_openpgp;
       if (!resource->handle_table)
         {
           resource->handle_table_size = 3;
@@ -135,6 +131,30 @@ keybox_new (void *token, int secret)
   return hd;
 }
 
+
+/* Create a new handle for the resource associated with TOKEN.  SECRET
+   is just a cross-check.  This is the OpenPGP version.  The returned
+   handle must be released using keybox_release.  */
+KEYBOX_HANDLE
+keybox_new_openpgp (void *token, int secret)
+{
+  KB_NAME resource = token;
+
+  return do_keybox_new (resource, secret, 1);
+}
+
+/* Create a new handle for the resource associated with TOKEN.  SECRET
+   is just a cross-check.  This is the X.509 version.  The returned
+   handle must be released using keybox_release.  */
+KEYBOX_HANDLE
+keybox_new_x509 (void *token, int secret)
+{
+  KB_NAME resource = token;
+
+  return do_keybox_new (resource, secret, 0);
+}
+
+
 void
 keybox_release (KEYBOX_HANDLE hd)
 {
diff --git a/kbx/keybox-update.c b/kbx/keybox-update.c
index 6ade9e79c..693b7324a 100644
--- a/kbx/keybox-update.c
+++ b/kbx/keybox-update.c
@@ -211,18 +211,18 @@ rename_tmp_file (const char *bakfname, const char *tmpfname,
 
 
 
-/* Perform insert/delete/update operation.
-   MODE is one of FILECOPY_INSERT, FILECOPY_DELETE, FILECOPY_UPDATE.
-*/
+/* Perform insert/delete/update operation.  MODE is one of
+   FILECOPY_INSERT, FILECOPY_DELETE, FILECOPY_UPDATE.  FOR_OPENPGP
+   indicates that this is called due to an OpenPGP keyblock change.  */
 static int
 blob_filecopy (int mode, const char *fname, KEYBOXBLOB blob,
-               int secret, off_t start_offset)
+               int secret, int for_openpgp, off_t start_offset)
 {
   FILE *fp, *newfp;
   int rc=0;
   char *bakfname = NULL;
   char *tmpfname = NULL;
-  char buffer[4096];
+  char buffer[4096];  /* (Must be at least 32 bytes) */
   int nread, nbytes;
 
   /* Open the source file. Because we do a rename, we have to check the
@@ -239,7 +239,7 @@ blob_filecopy (int mode, const char *fname, KEYBOXBLOB blob,
       if (!newfp )
         return gpg_error_from_syserror ();
 
-      rc = _keybox_write_header_blob (newfp);
+      rc = _keybox_write_header_blob (newfp, for_openpgp);
       if (rc)
         return rc;
 
@@ -275,9 +275,19 @@ blob_filecopy (int mode, const char *fname, KEYBOXBLOB blob,
   /* prepare for insert */
   if (mode == FILECOPY_INSERT)
     {
-      /* Copy everything to the new file. */
+      int first_record = 1;
+
+      /* Copy everything to the new file.  If this is for OpenPGP, we
+         make sure that the openpgp flag is set in the header.  (We
+         failsafe the blob type.) */
       while ( (nread = fread (buffer, 1, DIM(buffer), fp)) > 0 )
         {
+          if (first_record && for_openpgp && buffer[4] == BLOBTYPE_HEADER)
+            {
+              first_record = 0;
+              buffer[7] |= 0x02; /* OpenPGP data may be available.  */
+            }
+
           if (fwrite (buffer, nread, 1, newfp) != 1)
             {
               rc = gpg_error_from_syserror ();
@@ -409,7 +419,7 @@ keybox_insert_keyblock (KEYBOX_HANDLE hd, const void *image, size_t imagelen,
   _keybox_destroy_openpgp_info (&info);
   if (!err)
     {
-      err = blob_filecopy (FILECOPY_INSERT, fname, blob, hd->secret, 0);
+      err = blob_filecopy (FILECOPY_INSERT, fname, blob, hd->secret, 1, 0);
       _keybox_release_blob (blob);
       /*    if (!rc && !hd->secret && kb_offtbl) */
       /*      { */
@@ -462,7 +472,7 @@ keybox_update_keyblock (KEYBOX_HANDLE hd, const void *image, size_t imagelen)
   /* Update the keyblock.  */
   if (!err)
     {
-      err = blob_filecopy (FILECOPY_UPDATE, fname, blob, hd->secret, off);
+      err = blob_filecopy (FILECOPY_UPDATE, fname, blob, hd->secret, 1, off);
       _keybox_release_blob (blob);
     }
   return err;
@@ -495,7 +505,7 @@ keybox_insert_cert (KEYBOX_HANDLE hd, ksba_cert_t cert,
   rc = _keybox_create_x509_blob (&blob, cert, sha1_digest, hd->ephemeral);
   if (!rc)
     {
-      rc = blob_filecopy (FILECOPY_INSERT, fname, blob, hd->secret, 0);
+      rc = blob_filecopy (FILECOPY_INSERT, fname, blob, hd->secret, 0, 0);
       _keybox_release_blob (blob);
       /*    if (!rc && !hd->secret && kb_offtbl) */
       /*      { */
@@ -743,8 +753,10 @@ keybox_compress (KEYBOX_HANDLE hd)
           first_blob = 0;
           if (length > 4 && buffer[4] == BLOBTYPE_HEADER)
             {
-              /* Write out the blob with an updated maintenance time stamp. */
-              _keybox_update_header_blob (blob);
+              /* Write out the blob with an updated maintenance time
+                 stamp and if needed (ie. used by gpg) set the openpgp
+                 flag.  */
+              _keybox_update_header_blob (blob, hd->for_openpgp);
               rc = _keybox_write_blob (blob, newfp);
               if (rc)
                 break;
@@ -752,7 +764,7 @@ keybox_compress (KEYBOX_HANDLE hd)
             }
 
           /* The header blob is missing.  Insert it.  */
-          rc = _keybox_write_header_blob (newfp);
+          rc = _keybox_write_header_blob (newfp, hd->for_openpgp);
           if (rc)
             break;
           any_changes = 1;
diff --git a/kbx/keybox.h b/kbx/keybox.h
index 96c6db549..9067fb8a4 100644
--- a/kbx/keybox.h
+++ b/kbx/keybox.h
@@ -62,7 +62,8 @@ typedef enum
 void *keybox_register_file (const char *fname, int secret);
 int keybox_is_writable (void *token);
 
-KEYBOX_HANDLE keybox_new (void *token, int secret);
+KEYBOX_HANDLE keybox_new_openpgp (void *token, int secret);
+KEYBOX_HANDLE keybox_new_x509 (void *token, int secret);
 void keybox_release (KEYBOX_HANDLE hd);
 void keybox_push_found_state (KEYBOX_HANDLE hd);
 void keybox_pop_found_state (KEYBOX_HANDLE hd);
@@ -74,7 +75,7 @@ int keybox_lock (KEYBOX_HANDLE hd, int yes);
 /*-- keybox-file.c --*/
 /* Fixme: This function does not belong here: Provide a better
    interface to create a new keybox file.  */
-int _keybox_write_header_blob (FILE *fp);
+int _keybox_write_header_blob (FILE *fp, int openpgp_flag);
 
 /*-- keybox-search.c --*/
 gpg_error_t keybox_get_keyblock (KEYBOX_HANDLE hd, iobuf_t *r_iobuf,