Raspberry PI / Android a minimal cross-compile configuration

Enable a cross compile Erlang/OTP platform to Android or Raspberry PI
using Android NDK. Port emulator and core application to support target
HW platform. Exclude any add-on services required for OTP platform deployment
into target hardware due to device fragmentation and jail-break requirements.

 * fix erts/emulator/beam/sys.h
   Disable redefinition of __noreturn macro

 * port erts/emulator/sys/unix/erl_child_setup.c
   Use techniques proposed by https://code.google.com/p/erlang4android to
   access system properties

 * fix erts/emulator/sys/unix/erl_unix_sys_ddll.c
   The static linking of emulator cannot find dlerror(), dlopen() symbols

 * port erts/emulator/sys/unix/sys.c
   make path to shell configurable at build time

 * port erts/etc/common/Makefile.in
   disable librt for *-linux-androideabi

 * port erts/lib_src/pthread/ethread.c
   Use techniques proposed by https://code.google.com/p/erlang4android to
   disable emulator crash if kernel threads are on. Replace unreliable
   pthread_sigmask() by sigprocmask()

 * port lib/erl_interface/src/connect/ei_connect.c
   Disable call to undefined gethostid()

 * port lib/erl_interface/src/connect/ei_resolve.c
   Use gethostbyname_r() on Android platform

3 files changed, 51 insertions, 3 deletions

diff --git a/erts/emulator/sys/unix/erl_child_setup.c b/erts/emulator/sys/unix/erl_child_setup.c
index 7c6e4a2f37..34d7f9e0e5 100644
--- a/erts/emulator/sys/unix/erl_child_setup.c
+++ b/erts/emulator/sys/unix/erl_child_setup.c
@@ -54,6 +54,17 @@ void sys_sigrelease(int sig)
 #endif /* !SIG_SIGNAL */
 #endif /* !SIG_SIGSET */
 
+#if defined(__ANDROID__)
+int __system_properties_fd(void);
+#endif /* __ANDROID__ */
+
+#if defined(__ANDROID__)
+#define SHELL "/system/bin/sh"
+#else
+#define SHELL "/bin/sh"
+#endif /* __ANDROID__ */
+
+
 int
 main(int argc, char *argv[])
 {
@@ -89,8 +100,16 @@ main(int argc, char *argv[])
 
     if (sscanf(argv[CS_ARGV_FD_CR_IX], "%d:%d", &from, &to) != 2)
 	return 1;
+
+#if defined(__ANDROID__)
+    for (i = from; i <= to; i++) {
+	if (i!=__system_properties_fd)
+	    (void) close(i);
+    }
+#else
     for (i = from; i <= to; i++)
 	(void) close(i);
+#endif /* __ANDROID__ */
 
     if (!(argv[CS_ARGV_WD_IX][0] == '.' && argv[CS_ARGV_WD_IX][1] == '\0')
 	&& chdir(argv[CS_ARGV_WD_IX]) < 0)
@@ -116,7 +135,25 @@ main(int argc, char *argv[])
 	    execv(argv[CS_ARGV_NO_OF_ARGS],&(argv[CS_ARGV_NO_OF_ARGS + 1]));
 	}
     } else {
-	execl("/bin/sh", "sh", "-c", argv[CS_ARGV_CMD_IX], (char *) NULL);
+        execl(SHELL, "sh", "-c", argv[CS_ARGV_CMD_IX], (char *) NULL);
     }
     return 1;
 }
+
+
+
+#if defined(__ANDROID__)
+int __system_properties_fd(void)
+{
+    int s, fd;
+    char *env;
+
+    env = getenv("ANDROID_PROPERTY_WORKSPACE");
+    if (!env) {
+        return -1;
+    }
+    fd = atoi(env);
+    return fd;
+}
+#endif /* __ANDROID__ */
+
diff --git a/erts/emulator/sys/unix/erl_unix_sys_ddll.c b/erts/emulator/sys/unix/erl_unix_sys_ddll.c
index 8760b58839..2659d623c7 100644
--- a/erts/emulator/sys/unix/erl_unix_sys_ddll.c
+++ b/erts/emulator/sys/unix/erl_unix_sys_ddll.c
@@ -123,6 +123,7 @@ int erts_sys_ddll_open(const char *full_name, void **handle, ErtsSysDdllError* e
 
 int erts_sys_ddll_open_noext(char *dlname, void **handle, ErtsSysDdllError* err)
 {
+#if defined(HAVE_DLOPEN)   
     int ret = ERL_DE_NO_ERROR;
     char *str;
     dlerror();
@@ -148,6 +149,9 @@ int erts_sys_ddll_open_noext(char *dlname, void **handle, ErtsSysDdllError* err)
 	ret = ERL_DE_DYNAMIC_ERROR_OFFSET - find_errcode(str, err);
     }
     return ret;
+#else
+    return ERL_DE_ERROR_NO_DDLL_FUNCTIONALITY;
+#endif
 }
 
 /* 
diff --git a/erts/emulator/sys/unix/sys.c b/erts/emulator/sys/unix/sys.c
index 865cb50a56..c3d7440409 100644
--- a/erts/emulator/sys/unix/sys.c
+++ b/erts/emulator/sys/unix/sys.c
@@ -149,6 +149,13 @@ extern void erl_crash_dump(char* file, int line, char* fmt, ...);
 
 #define DIR_SEPARATOR_CHAR    '/'
 
+#if defined(__ANDROID__)
+#define SHELL "/system/bin/sh"
+#else
+#define SHELL "/bin/sh"
+#endif /* __ANDROID__ */
+
+
 #if defined(DEBUG)
 #define ERL_BUILD_TYPE_MARKER ".debug"
 #elif defined(PURIFY)
@@ -1596,7 +1603,7 @@ static ErlDrvData spawn_start(ErlDrvPort port_num, char* name, SysDriverOpts* op
 		    }
 		}
 	    } else {
-		execle("/bin/sh", "sh", "-c", cmd_line, (char *) NULL, new_environ);
+		execle(SHELL, "sh", "-c", cmd_line, (char *) NULL, new_environ);
 	    }
 	child_error:
 	    _exit(1);
@@ -1717,7 +1724,7 @@ static ErlDrvData spawn_start(ErlDrvPort port_num, char* name, SysDriverOpts* op
 	fcntl(i, F_SETFD, 1);
 
     qnx_spawn_options.flags = _SPAWN_SETSID;
-    if ((pid = spawnl(P_NOWAIT, "/bin/sh", "/bin/sh", "-c", cmd_line, 
+    if ((pid = spawnl(P_NOWAIT, SHELL, SHELL, "-c", cmd_line, 
                       (char *) 0)) < 0) {
 	erts_free(ERTS_ALC_T_TMP, (void *) cmd_line);
         reset_qnx_spawn();