Fix ttyname problem on Android.

* configure.ac: Define macro and conditional HAVE_ANDROID_SYSTEM.
* m4/gnupg-ttyname.m4: Force use of replacement on Android.
* src/ttyname_r.c: Ditto.
--

Android's bionic lib has no working ttyname_r() nor ttyname().  Using
them anyway will print

  FIX ME! implement ttyname_r() bionic/libc/bionic/stubs.c:466

Thus we force the use of our replacement code which simply return
"/dev/tty".

configure.ac

@@ -131,6 +131,7 @@ GPGCONF_DEFAULT=no
 G13_DEFAULT=no
 component_system=None
 have_dosish_system=no
+have_android_system=no
 have_w32_system=no
 have_w64_system=no
 build_w32_glib=no
@@ -142,6 +143,9 @@ case "${host}" in
     *-mingw32ce*)
         have_w32ce_system=yes
 	;;
+    *-linux-androideabi)
+        have_android_system=yes
+        ;;
 esac
 case "${host}" in
     *-mingw32ce*|*-mingw32*)
@@ -210,6 +214,11 @@ if test "$have_w32ce_system" = yes; then
 fi
 AM_CONDITIONAL(HAVE_W32CE_SYSTEM, test "$have_w32ce_system" = yes)
 
+if test "$have_android_system" = yes; then
+   AC_DEFINE(HAVE_ANDROID_SYSTEM,1, [Defined if we build for an Android system])
+fi
+AM_CONDITIONAL(HAVE_ANDROID_SYSTEM, test "$have_android_system" = yes)
+
 AM_CONDITIONAL(BUILD_W32_GLIB, test "$build_w32_glib" = yes)
 AM_CONDITIONAL(BUILD_W32_QT, test "$build_w32_qt" = yes)
 

m4/gnupg-ttyname.m4

@@ -27,6 +27,9 @@
 # The macro REPLACE_TTYNAME_R is defined if ttyname_r is a replacement
 # function.  This macro is useful for the definition of the prototype.
 #
+# If the macro "have_android_system" has a value of "yes", ttyname_r
+# will also be replaced by our own function.
+#
 AC_DEFUN([gnupg_REPLACE_TTYNAME_R],
 [
   AC_CHECK_HEADERS([unistd.h])
@@ -60,6 +63,12 @@ AC_DEFUN([gnupg_REPLACE_TTYNAME_R],
     if test $gnupg_cv_func_ttyname_r_posix = no; then
       AC_LIBOBJ([ttyname_r])
       AC_DEFINE([REPLACE_TTYNAME_R],[1])
+    elif test "$have_android_system" = yes; then
+      # Android has ttyname and ttyname_r but they are only stubs and
+      # print an annoying warning message.  Thus we need to replace
+      # ttyname_r with our own dummy function.
+      AC_LIBOBJ([ttyname_r])
+      AC_DEFINE([REPLACE_TTYNAME_R],[1])
     else
       AC_DEFINE([HAVE_POSIXDECL_TTYNAME_R], [1],
         [Define if the ttyname_r function has a POSIX compliant declaration.])

src/ttyname_r.c

@@ -32,6 +32,12 @@
 # warning ttyname is not thread-safe, and ttyname_r is missing
 #endif
 
+/* For Android we force the use of our replacement code.  */
+#if HAVE_ANDROID_SYSTEM
+# undef HAVE_TTYNAME_R
+#endif
+
+
 int
 _gpgme_ttyname_r (int fd, char *buf, size_t buflen)
 {
@@ -110,12 +116,11 @@ _gpgme_ttyname_r (int fd, char *buf, size_t buflen)
 #else /*!HAVE_TTYNAME_R*/
   char *tty;
 
-# if HAVE_W32_SYSTEM
+# if HAVE_W32_SYSTEM || HAVE_ANDROID_SYSTEM
   /* We use this default one for now.  AFAICS we only need it to be
      passed to gpg and in turn to pinentry.  Providing a replacement
-     is needed because elsewhere we bail out on error.  If we
-     eventually implement a pinentry for Windows it is inlikely that
-     we need a real tty at all.  */
+     is needed because elsewhere we bail out on error or Android
+     provided ttyname_r prints an error message if used. */
   tty = "/dev/tty";
 # else
   tty = ttyname (fd);