src/user/ps.nsc

include "syscalls.nsh";
include "stdio.nsh";
 
/* "ps is literal ls /proc essentially" -- this is
 * even more literal than that: /proc/ps (virtfs.nsc, kernel-side) is a
 * real virtual file that's regenerated fresh on every read from
 * exec.nsc's own process table (sh itself, plus whatever single
 * command it's currently running -- see that file's own note on why
 * that's the whole real process tree kaboom has), and this command is
 * nothing but a hardcoded cat of it. */
global i32
main(i32 argc, ptr argv)
{
	i8 buf[512];
	i32 fd;
	i64 n;
 
	fd = sys_open("/proc/ps", (u64)8);
	if(fd < 0)
	{
		print_err(2, "ps", "/proc/ps not found");
		return 1;
	}
	n = sys_read(fd, &buf[0], (u64)512);
	sys_close(fd);
	if(n < (i64)0)
	{
		print_err(2, "ps", "read failed");
		return 1;
	}
	sys_write(1, &buf[0], (u64)n);
	return 0;
}