system-calls

I'm currently working on the back-end of ACM-like public programming contest system. In such system, any user can submit a code source, which will be compiled and run automatically (which means, no human-eye pre-moderation is performed) in attempt to solve some computational problem. Back-end is a GNU/Linux dedicated machine, where a user will be created for each contestant, all such users being part of users group. Sources sent by any particular user will be stored at the user's home directory, then compiled and executed to be verified against various test cases. What I want is to prohibit

One of the Linux kernel drivers I am developing is using network communication in the kernel ( sock_create() , sock->ops->bind() , and so on). The problem is there will be multiple sockets to receive data from. So I need something that will simulate a select() or poll() in kernel space. Since these functions use file descriptors, I cannot use the system calls unless I use the system calls to create the sockets, but that seems unnecessary since I am working in the kernel. So I was thinking of wrapping the default sock->sk_data_ready handler in my own handler ( custom_sk_data_ready() ), which

I have been trying to write a new system call(called sys_defclose) in the raspberry's kernel, but upon compiling i get this error: arch/arm/kernel/built-in.o: In function `__sys_trace_return': :(.text+0xd50): undefined reference to `sys_defclose' i have modified the following file: -include/linux/syscalls.h : where i put the prototype of my syscall -arch/arm/include/asm/unistd.h : where i put the new raw of the syscall table: #define __NR_sys_defclose (__NR_SYSCALL_BASE+380) -arch/arm/kernel/calls.S : where i put: CALL(sys_defclose) -i put the source of sys_defclose in arch/arm/kernel and i

I am now trying to understand how read(2) function works by looking into the actual code implementation and first, I try to see how it is defined in #include header file. In that file, I found this : ssize_t read(int, void *, size_t) __DARWIN_ALIAS_C(read); And then, I googled to find the actual read() function declaration. And, https://github.com/lattera/glibc/blob/master/io/read.c I found this. In this code, /* Read NBYTES into BUF from FD. Return the number read or -1. */ ssize_t __libc_read (int fd, void *buf, size_t nbytes) { if (nbytes == 0) return 0; if (fd < 0) { __set_errno (EBADF);

I want to know who called *sys_reboot* when the phone(android) reboot unexpectly. Is there a way to dump the call stack in syscall (android kernel)? FrankH. If all you want it a kernel call trace, you can get that via dump_stack() . panic() calls that, amongst other things. The BUG() / BUG_ON() wrappers give it a more descriptive message and an optional conditional test. A userland stacktrace , particularly a symbolic one, though, cannot reliably be obtained from within the kernel directly. It's possible to copy the stack memory into kernel space and log the contents, or even heuristically