Question

I wonder to find out the codes of the function “sys_access”, but i could only find it`s declare:(in include\Syscalls.h)

asmlinkage long sys_access(const char __user *filename, int mode);

i guess it coded by Assemble, but how could i found that?
by the way , i use the source insight to read the linux kernel…it cannot find the symbol in file *.S . Is there more effective tools to read the linux kernel?

Answer 1

I assume that you have already downloaded kernel sources (not only headers). This function is implemented in C and placed in fs/open.c:

SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
{
     ...
}

SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
{
        return sys_faccessat(AT_FDCWD, filename, mode);
}

There are a bunch of methods to search trough files contents. In simple cases I prefer the usage of grep:

$> grep -r "access" /usr/src/linux-2.6/*