New Windows API gpgrt_w32_reg_get_string.

* src/w32-reg.c (_gpgrt_w32_reg_query_string): Implement a prefix for
root and consider an empty string for root also HKCU.
* src/visibility.c (gpgrt_w32_reg_get_string): New.
* src/gpg-error.def.in: Add new function.

* src/gpg-error.c (my_strusage): Print the Windows version (32 or 64
bit) of the binary.
(main): New command --getreg.
--

This function is already used internally and we have a similar
function in GnuPG.  It is much more convenient to work with this
function.

Also we can now pass the KEY_WOW64_32KEY andKEY_WOW64_64KEY flags to
the registry read functions.  For example

  !32key!HKLM\software\gnu\gnupg:ntdskeyserver

returns the value using the KEY_WOW64_32KEY flag; likewise for
!64key!.  If !cross! is used the reversed flag of the binary type is
used.

7 files changed, 99 insertions, 8 deletions

diff --git a/NEWS b/NEWS
index cfe348c..4bade72 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,15 @@
 Noteworthy changes in version 1.52 (unreleased) [C38/A38/R_]
 -----------------------------------------------
 
+ * The KEY_WOW64_xxKEY flags can now be passed to the Regsiry read
+   functions.
+
+ * New command --getreg for gpg-error on Windows.
+
+ * Interface changes relative to the 1.51 release:
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ _gpgrt_w32_reg_query_string         NEW (Windows only).
+
 
  Release-info: https://dev.gnupg.org/T7385
 
diff --git a/src/gpg-error.c b/src/gpg-error.c
index 4e8bd8b..6d16b36 100644
--- a/src/gpg-error.c
+++ b/src/gpg-error.c
@@ -521,6 +521,16 @@ my_strusage (int level)
     case 14: p = "Copyright (C) 2019 g10 Code GmbH"; break;
     case 19: p = _("Please report bugs to <https://bugs.gnupg.org>.\n"); break;
 
+#ifdef HAVE_W32_SYSTEM
+    case 31:
+#if defined(_WIN64)
+      p = "(Windows 64 bit)";
+#else
+      p = "(Windows 32 bit)";
+#endif
+      break;
+#endif
+
     case 1:
     case 40:
       p = ("Usage: gpg-error [options] error-numbers");
@@ -548,6 +558,7 @@ main (int argc, char *argv[])
          CMD_LIST,
          CMD_DEFINES,
          CMD_LOCALE,
+         CMD_GETREG,
          OPT_DESC
   };
   static gpgrt_opt_t opts[] = {
@@ -559,10 +570,14 @@ main (int argc, char *argv[])
                 "Print all error codes as #define lines"),
 #if HAVE_W32_SYSTEM
     ARGPARSE_c (CMD_LOCALE, "locale",
-                "Return the locale used for gettext"),
+                "Print the locale used for gettext"),
+    ARGPARSE_c (CMD_GETREG, "getreg",
+                "Print string from the Registry"),
 #else
     ARGPARSE_c (CMD_LOCALE, "locale",
                 "@"),
+    ARGPARSE_c (CMD_GETREG, "getreg",
+                "@"),
 #endif
     ARGPARSE_s_n (OPT_DESC, "desc",
                   "Print with error description"),
@@ -574,6 +589,7 @@ main (int argc, char *argv[])
   int libversion = 0;
   int listmode = 0;
   int localemode = 0;
+  int getregmode = 0;
   int desc = 0;
   const char *s, *s2;
   const char *source_sym;
@@ -594,6 +610,7 @@ main (int argc, char *argv[])
         case CMD_LIST:       listmode = 1; break;
         case CMD_DEFINES:    listmode = 2; break;
         case CMD_LOCALE:     localemode = 1; break;
+        case CMD_GETREG:     getregmode = 1; break;
         case OPT_DESC:       desc = 1; break;
         default: pargs.err = ARGPARSE_PRINT_WARNING; break;
         }
@@ -610,6 +627,11 @@ main (int argc, char *argv[])
       if (argc > 1)
         gpgrt_usage (1);
     }
+  else if (getregmode)
+    {
+      if (argc != 1)
+        gpgrt_usage (1);
+    }
   else if ((argc && listmode) || (!argc && !listmode))
     gpgrt_usage (1);
 
@@ -658,6 +680,14 @@ main (int argc, char *argv[])
       log_info ("this command is only useful on Windows\n");
 #endif
     }
+  else if (getregmode)
+    {
+#if HAVE_W32_SYSTEM
+      printf ("%s\n", gpgrt_w32_reg_get_string (*argv));
+#else
+      log_info ("this command is only useful on Windows\n");
+#endif
+    }
   else if (listmode == 1)
     {
       for (i=0; i <  GPG_ERR_SOURCE_DIM; i++)
diff --git a/src/gpg-error.def.in b/src/gpg-error.def.in
index 4344cbc..fad6405 100644
--- a/src/gpg-error.def.in
+++ b/src/gpg-error.def.in
@@ -256,4 +256,6 @@ EXPORTS
  gpgrt_spawn_actions_set_inherit_handles @196
  gpgrt_spawn_actions_set_env_rev         @197
 
+ gpgrt_w32_reg_get_string     @198
+
 ;; end of file with public symbols for Windows.
diff --git a/src/visibility.c b/src/visibility.c
index b7505b8..836d4d0 100644
--- a/src/visibility.c
+++ b/src/visibility.c
@@ -1380,4 +1380,10 @@ gpgrt_w32_reg_query_string (const char *root, const char *dir, const char *name)
   return _gpgrt_w32_reg_query_string (root, dir, name);
 }
 
+char *
+gpgrt_w32_reg_get_string (const char *key)
+{
+  return _gpgrt_w32_reg_get_string (key);
+}
+
 #endif /*HAVE_W32_SYSTEM*/
diff --git a/src/visibility.h b/src/visibility.h
index 30c6853..079dfb9 100644
--- a/src/visibility.h
+++ b/src/visibility.h
@@ -455,6 +455,7 @@ MARK_VISIBLE (gpgrt_spawn_actions_set_atfork)
 #define gpgrt_wchar_to_utf8         _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_fname_to_wchar        _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_w32_reg_query_string  _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpgrt_w32_reg_get_string    _gpgrt_USE_UNDERSCORED_FUNCTION
 
 
 #endif /*!_GPGRT_INCL_BY_VISIBILITY_C*/
diff --git a/src/w32-add.h b/src/w32-add.h
index d567799..dd6db5d 100644
--- a/src/w32-add.h
+++ b/src/w32-add.h
@@ -88,3 +88,6 @@ char *gpgrt_wchar_to_utf8 (const wchar_t *wstring);
 char *gpgrt_w32_reg_query_string (const char *root,
                                   const char *dir,
                                   const char *name);
+
+/* Query a string in the registry using a unified key representation.  */
+char *gpgrt_w32_reg_get_string (const char *key);
diff --git a/src/w32-reg.c b/src/w32-reg.c
index b1134a5..5bb8d43 100644
--- a/src/w32-reg.c
+++ b/src/w32-reg.c
@@ -47,10 +47,30 @@ _gpgrt_w32_reg_query_string (const char *root, const char *dir,
                              const char *name)
 {
   HKEY root_key, key_handle;
-  DWORD n1, nbytes, type;
+  DWORD n1, nbytes, type, flags;
   char *result = NULL;
+  int cross = 0;
 
+  /* Check special prefix.  */
   if (!root)
+    ;
+  else if (!strncmp (root, "!64key!", 7))
+    {
+      root += 7;
+      cross = 64;
+    }
+  else if (!strncmp (root, "!32key!", 7))
+    {
+      root += 7;
+      cross = 32;
+    }
+  else if (!strncmp (root, "!cross!", 7))
+    {
+      root += 7;
+      cross = 1;
+    }
+
+  if (!root || !*root)
     root_key = HKEY_CURRENT_USER;
   else if (!strcmp (root, "HKEY_CLASSES_ROOT") || !strcmp (root, "HKCR"))
     root_key = HKEY_CLASSES_ROOT;
@@ -67,12 +87,26 @@ _gpgrt_w32_reg_query_string (const char *root, const char *dir,
   else
     return NULL;
 
-  if (RegOpenKeyExA (root_key, dir, 0, KEY_READ, &key_handle))
+  flags = KEY_READ;
+  if (cross == 64)
+    flags |= KEY_WOW64_64KEY;
+  else if (cross == 32)
+    flags |= KEY_WOW64_32KEY;
+  else if (cross)
+    {
+#if defined(_WIN64)
+      flags |= KEY_WOW64_32KEY;
+#else
+      flags |= KEY_WOW64_64KEY;
+#endif
+    }
+
+  if (RegOpenKeyExA (root_key, dir, 0, flags, &key_handle))
     {
-      if (root)
+      if (root && !*root)
         return NULL; /* No need for a RegClose, so return direct.  */
       /* It seems to be common practise to fall back to HKLM. */
-      if (RegOpenKeyExA (HKEY_LOCAL_MACHINE, dir, 0, KEY_READ, &key_handle))
+      if (RegOpenKeyExA (HKEY_LOCAL_MACHINE, dir, 0, flags, &key_handle))
         return NULL; /* still no need for a RegClose, so return direct */
     }
 
@@ -81,11 +115,11 @@ _gpgrt_w32_reg_query_string (const char *root, const char *dir,
   nbytes = 1;
   if (RegQueryValueExA (key_handle, name, 0, NULL, NULL, &nbytes))
     {
-      if (root)
+      if (root && !*root)
         goto leave;
       /* Try to fallback to HKLM also for a missing value.  */
       RegCloseKey (key_handle);
-      if (RegOpenKeyExA (HKEY_LOCAL_MACHINE, dir, 0, KEY_READ, &key_handle))
+      if (RegOpenKeyExA (HKEY_LOCAL_MACHINE, dir, 0, flags, &key_handle))
         return NULL; /* Nope.  */
       if (RegQueryValueExA (key_handle, name, 0, NULL, NULL, &nbytes))
         goto leave;
@@ -170,8 +204,9 @@ _gpgrt_w32_reg_query_string (const char *root, const char *dir,
 /* Compact version of gpgrt_w32_reg_query_string.  This version
  * expects a single string as key described here using an example:
  *
- *    HKCU\Software\GNU\GnuPG:HomeDir
+ *    <prefix>HKCU\Software\GNU\GnuPG:HomeDir
  *
+ * <prefix> := Optional; see below.
  * HKCU := the class, other supported classes are HKLM, HKCR, HKU, and
  *         HKCC.  If no class is given and the string thus starts with
  *         a backslash HKCU with a fallback to HKLM is used.
@@ -179,6 +214,11 @@ _gpgrt_w32_reg_query_string (const char *root, const char *dir,
  * HomeDir := the name of the item.  The name is optional to use the default
  *            value.
  *
+ * If <prefix> is given it may take these values:
+ *    !64key! := Access a 64 bit key
+ *    !32key! := Access a 32 bit key
+ *    !cross! := On 32-bit use the 64-bit key, on 64-bit use the 32-bit key
+ *
  * Note that the first backslash and the first colon act as delimiters.
  *
  * Returns a malloced string or NULL if not found.