[android-developers] Re: Problem in Android-JNI IPC
Hi, this is not about developing for the SDK, so should be moved to one of
the open source groups. Thanks.
On Wed, Dec 3, 2008 at 6:10 AM, Pankaj Munjal [EMAIL PROTECTED]wrote:
Hello folks,
I have implemented a JNI layer for communication between the Android
Java Application and Android Native C code.
However, we are facing issues with IPC in this JNI layer.
I tried the following IPC approaches:
1. Socket in JNI layer: C Sockets to communicate with the underlying C
based processes.
I get an error in bind().
Sample code:
fd_recv_es = socket(AF_INET,SOCK_DGRAM,0);
if (0 fd_recv_es)
{
return (FAILURE);
}
bzero(es_recv_addr, sizeof(es_recv_addr));
es_recv_addr.sin_family = AF_INET;
es_recv_addr.sin_port = htons(self_port);
es_recv_addr.sin_addr.s_addr = inet_addr(self_ip.str);
memset((es_recv_addr.sin_zero), '\0', 8);
if ( -1 == bind( fd_recv_es,(struct sockaddr*)(es_recv_addr),
sizeof(struct sockaddr_in))) // Fails here
{
return (FAILURE);
}
2. Message Q in JNI layer: Linux based message queue to communicate
with the underlying C based processes.
I get an error in creating the
message queue.
Sample Code:
struct my_msgbuf buf;
int msqid, i;
key_t key;
if ((key = ftok(/data/IPC/dummy, 'B')) == -1)
{
perror(ftok);
exit(1);
}
if ((msqid = msgget(key, 0644 | IPC_CREAT)) == -1) // Fails
here
{
perror(msgget);
exit(1);
}
Both these approaches work perfectly fine when I use them in an
Android C executable,
and we are getting this problem only when we use them in a JNI DLL.
The linking command for the building JNI DLL is:
ALIB := $(NDK_BASE)/toolchain/arm-eabi/lib/gcc/arm-eabi/4.2.1/
libgcc.a
$(CC) -nostdlib -Wl,-soname,libApp.so -Wl,-shared,-Bsymbolic
-L$(NDK_BASE)/lib $^ $(LIBS) -o libApp.so -Wl,--no-undefined
$(ALIB)
Has anyone faced a similar issues with IPC(with C executables) in JNI
layer?
Also, are there are some other flags required for building a JNI DLL
that I've missed out on.
Any pointers in this direction shall be really helpful.
Thanks,
Pankaj
--
Dianne Hackborn
Android framework engineer
[EMAIL PROTECTED]
Note: please don't send private questions to me, as I don't have time to
provide private support. All such questions should be posted on public
forums, where I and others can see and answer them.
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[android-developers] Re: Problem in Android-JNI IPC
You'll need to add network access permissions to the manifest for the
Android application that is loading the shared object.
For the second issue, I had noticed that message queues work fine on
the emulator, but fail on target. After a closer examination using
strace, I realized that system call SYS_303 is supported on the
emulator but not on the target. Stick to socket or some other IPC
mechanism.
--Ashu
On Dec 3, 6:10 am, Pankaj Munjal [EMAIL PROTECTED] wrote:
Hello folks,
I have implemented a JNI layer for communication between the Android
Java Application and Android Native C code.
However, we are facing issues withIPCin this JNI layer.
I tried the followingIPCapproaches:
1. Socket in JNI layer: C Sockets to communicate with the underlying C
based processes.
I get an error in bind().
Sample code:
fd_recv_es = socket(AF_INET,SOCK_DGRAM,0);
if (0 fd_recv_es)
{
return (FAILURE);
}
bzero(es_recv_addr, sizeof(es_recv_addr));
es_recv_addr.sin_family = AF_INET;
es_recv_addr.sin_port = htons(self_port);
es_recv_addr.sin_addr.s_addr = inet_addr(self_ip.str);
memset((es_recv_addr.sin_zero), '\0', 8);
if ( -1 == bind( fd_recv_es,(struct sockaddr*)(es_recv_addr),
sizeof(struct sockaddr_in))) // Fails here
{
return (FAILURE);
}
2. Message Q in JNI layer: Linux based message queue to communicate
with the underlying C based processes.
I get an error in creating the
message queue.
Sample Code:
struct my_msgbuf buf;
int msqid, i;
key_t key;
if ((key = ftok(/data/IPC/dummy, 'B')) == -1)
{
perror(ftok);
exit(1);
}
if ((msqid = msgget(key, 0644 | IPC_CREAT)) == -1) // Fails
here
{
perror(msgget);
exit(1);
}
Both these approaches work perfectly fine when I use them in an
Android C executable,
and we are getting thisproblemonly when we use them in a JNI DLL.
The linking command for the building JNI DLL is:
ALIB := $(NDK_BASE)/toolchain/arm-eabi/lib/gcc/arm-eabi/4.2.1/
libgcc.a
$(CC) -nostdlib -Wl,-soname,libApp.so -Wl,-shared,-Bsymbolic
-L$(NDK_BASE)/lib $^ $(LIBS) -o libApp.so -Wl,--no-undefined
$(ALIB)
Has anyone faced a similar issues withIPC(with C executables) in JNI
layer?
Also, are there are some other flags required for building a JNI DLL
that I've missed out on.
Any pointers in this direction shall be really helpful.
Thanks,
Pankaj
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