system-calls

For my OS class I'm supposed to implement Linux's cat using only system calls (no printf) Reading this reference I found it being used to print to a file. I guess I should manipulate ofstream. In the example appears: ofstream outfile ("new.txt",ofstream::binary); How can I make it write to the screen? EDIT: I realized this write() is part of iostream library, is this the same as the int write (int fd, char *buf , int size) system call? Write to the file descriptor for standard output or standard error (1 and 2 respectively). A system call is a service provided by Linux kernel. In C programming

This question already has answers here : How is the system call in Linux implemented? (6 answers) How does system calls work ? What are the operations happen during system call? There are various system call like open , read, write, socket etc. I would like to know how do they work in general ? In short, here's how a system call works: First, the user application program sets up the arguments for the system call. After the arguments are all set up, the program executes the "system call" instruction. This instruction causes an exception : an event that causes the processor to jump to a new

I writing a Linux system call map for the radare2 debugger. This means providing a huge static array mapping system call number to a syscall name name and the number of arguments it takes. This was easy for OpenBSD as the syscall numbers are defined in sys/syscall.h and in a comment above each is the number of args. It was just a matter of writing a script to parse this and throw out the C code for the array. On linux however, we do not have this luxury. It is easy to get the syscall number from the kernel headers, but how should I get the number of args? The only ideas I have are: 1) Type

I want to implement a "process wrapper" in Go. Basically what it will do, is launch a process (lets say a node server) and monitor it (catch signals like SIGKILL, SIGTERM ...) I think the way to do is to launch the node server in a go routine using syscall.Exec : func launchCmd(path string, args []string) { err := syscall.Exec(path, args, os.Environ()) if err != nil { panic(err) } } Then I'd like to catch every possible signals generated by the command executed by syscall . I'm pretty new to Go, any help would be appreciated. Luke There are three ways of executing a program in Go: syscall

I'm looking for some good code examples of dynamic memory allocation using an assembly language under Linux and using system calls, not malloc and friends. What are some of the simplest but effective ways to do this? On Intel 386+ computers. brk(2) . And take a look at ELF . On Linux mmap2 is a sensible system call to use for this at a low level. It takes 6 arguments, so in IA32 you can call it using: mov eax, 192 ; mmap2 xor ebx, ebx ; addr = NULL mov ecx, 4096 ; len = 4096 mov edx, $7 ; prot = PROT_READ|PROT_WRITE|PROT_EXEC mov esi, $22 ; flags = MAP_PRIVATE|MAP_ANONYMOUS mov edi, -1 ; fd =

I just want to ask, I know that standart system calls in Linux are done by int instruction pointing into Interrupt Vector Table. I assume this is similiar on Windows. But, how do you call some higher-level specific system routines? Such as how do you tell Windows to create a window? I know this is handled by the code in the dll, but what actually happend at assembler-instruction level? Does the routine in dll calls software interrupt by int instruction, or is there any different approach to handle this? Thanks. Making a Win32 call to create a window is not really related to an interrupt. The

My purspose was to set ulimit -n from within a golang program so that I do not have to set it globally but restrict it within the program. Found systemcalls setrlimit and get rlimit for the same. ( http://linux.die.net/man/2/setrlimit ) But when I tried a sample program for the same I was getting an error saying invalid argument while setting the value. package main import ( "fmt" "syscall" ) func main() { var rLimit syscall.Rlimit err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rLimit) if err != nil { fmt.Println("Error Getting Rlimit ", err) } fmt.Println(rLimit) rLimit.Max = 999999 rLimit