I am working on a project in which I need to know the current working directory of the executable which called the system call. I think it would be possible as some system calls like open would make use of that information.
Could you please tell how I can get the current working directory path in a string?
You can look at how the getcwd syscall is implemented to see how to do that.
That syscall is in fs/dcache.c and calls:
get_fs_root_and_pwd(current->fs, &root, &pwd); root and pwd are struct path variables,
That function is defined as an inline function in include/linux/fs_struct.h, which also contains:
static inline void get_fs_pwd(struct fs_struct *fs, struct path *pwd) and that seems to be what you are after.
struct path. Did I misunderstand your question, and you are not actually writing kernel code?get_fs_pwd in the code.In newer kernels things changed a little bit. You can use this to get the current working directory:
#include <linux/init.h> // module_{init,exit}() #include <linux/module.h> #include <linux/kernel.h> #include <linux/dcache.h> // dentry_path_raw #include <linux/fs_struct.h> // get_fs_pwd static int __init get_cwd_module_init(void) { struct path abs_path; char *buf, *full_path; buf = __getname(); if (!buf) return -ENOMEM; get_fs_pwd(current->fs, &abs_path); full_path = dentry_path_raw(abs_path.dentry, buf, PATH_MAX); if (IS_ERR(full_path)) { pr_err("dentry_path_raw failed: %li", PTR_ERR(full_path)); } else { pr_info("Full path: '%s'", full_path); } __putname(buf); path_put(&abs_path); } static void __exit get_cwd_module_exit(void) { pr_info("exiting..."); } module_init(get_cwd_module_init) module_exit(get_cwd_module_exit) MODULE_AUTHOR("garlix"); MODULE_LICENSE("GPL"); 
How do you do that in a terminal ? You use pwd which looks at the environment variable named PWD.
#include <stdlib.h> int main(int ac, char **av) { printf("%s\n", getenv("PWD"); return 0; } If you want to know in which directory the executable is located you can combine the information from getenv and from argv[0].
