Fix link error with Android NDK r9

Since Android ndk r9, __set_errno is deprecated. It is now defined as
inline function in errno.h. The syscall assembly calls __set_errno,
but since libc.so does not export it, the link fails. To workaround
this, replace all occurrences of __set_errno with a2_set_errno and
define it as normal C function.

configure.ac

@@ -869,6 +869,7 @@ AC_SUBST([bashcompletiondir])
 
 case "$host" in
   *android*)
+    android=yes
     LIBS="$LIBS -lstdc++ -lsupc++"
     case "$host" in
       arm-*)
@@ -886,6 +887,7 @@ case "$host" in
     ;;
 esac
 
+AM_CONDITIONAL([ANDROID], [test "x$android" = "xyes"])
 AM_CONDITIONAL([ANDROID_ARM], [test "x$android_arm" = "xyes"])
 AM_CONDITIONAL([ANDROID_MIPS], [test "x$android_mips" = "xyes"])
 AM_CONDITIONAL([ANDROID_X86], [test "x$android_x86" = "xyes"])

src/Makefile.am

@@ -253,6 +253,10 @@ SRCS =  option_processing.cc\
 	FtpTunnelRequestConnectChain.h\
 	Lock.h
 
+if ANDROID
+SRCS += android/android.c
+endif # ANDROID
+
 # Android NDK R8e does not provide ftruncate64. Use assembly code from
 # android source code and link it.
 if ANDROID_ARM

src/android/android.c

@@ -0,0 +1,48 @@
+/* <!-- copyright */
+/*
+ * aria2 - The high speed download utility
+ *
+ * Copyright (C) 2013 Tatsuhiro Tsujikawa
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link the code of portions of this program with the
+ * OpenSSL library under certain conditions as described in each
+ * individual source file, and distribute linked combinations
+ * including the two.
+ * You must obey the GNU General Public License in all respects
+ * for all of the code used other than OpenSSL.  If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so.  If you
+ * do not wish to do so, delete this exception statement from your
+ * version.  If you delete this exception statement from all source
+ * files in the program, then also delete it here.
+ */
+/* copyright --> */
+#include <errno.h>
+
+/*
+ * Since Android ndk r9, __set_errno is deprecated. It is now defined
+ * as inline function in errno.h. The syscall assembly calls
+ * __set_errno, but since libc.so does not export it, the link
+ * fails. To workaround this, replace all occurrences of __set_errno
+ * with a2_set_errno and define it here.
+ */
+int a2_set_errno(int n)
+{
+  errno = n;
+  return -1;
+}

src/android/arm-ftruncate64.S

@@ -11,5 +11,5 @@ ENTRY(ftruncate64)
     cmn     r0, #(MAX_ERRNO + 1)
     bxls    lr
     neg     r0, r0
-    b       __set_errno
+    b       a2_set_errno
 END(ftruncate64)

src/android/mips-ftruncate64.S

@@ -15,7 +15,7 @@ ftruncate64:
     j $ra
     nop
 1:
-    la $t9,__set_errno
+    la $t9,a2_set_errno
     j $t9
     nop
     .set reorder

src/android/x86-ftruncate64.S

@@ -17,7 +17,7 @@ ENTRY(ftruncate64)
     jb      1f
     negl    %eax
     pushl   %eax
-    call    __set_errno
+    call    a2_set_errno
     addl    $4, %esp
     orl     $-1, %eax
 1: