Obtain the absolute path of the executable file corresponding to the current process in the Linux kernel.

The title is very vague. I have been tossing this issue over the past two days. I will record the results.

Let's talk about how to do this at the application layer. It's easy:

# Include <stdio. h> <br/> # include <unistd. h> </P> <p> int main () {<br/> char link [100], path [100]; <br/> sprintf (link, "/proc/% d/EXE", getpid (); <br/> readlink (link, path, sizeof (PATH )); <br/> printf ("% s/n", PATH); <br/> return 0; <br/>}

At the kernel layer, all information about the current process is included in current. There are several related variables in current:

 

1. Current-> COMM: a 16-byte char array that records the segment path of the current process. That is to say, if the full path of the executable file of the current process is/home/yaog/test, the comm content is "test", but the full path cannot be obtained from comm.

 

2. Current-> mm/current-> active_mm: Specifies the mm_struct structure when the two variables are used to describe the virtual memory. And current-> MM

/Current-> active_mm is used to describe the page information of the current process. This looks a bit reliable. Sure enough:

# If linux_version_code> = 0x020616 <br/> P-> MM-> MMAP-> vm_file-> f_path.dentry-> d_name.name <br/> # else <br/> P-> MM-> MMAP-> vm_file-> f_dentry-> d_name.name <br/> # endif

You can get "test" in "/home/yaog/test ".

# If linux_version_code> = 0x020616 <br/> P-> MM-> MMAP-> vm_file-> f_path.dentry-> d_parent <br/> # else <br/> P-> MM-> MMAP-> vm_file-> f_dentry-> d_parent <br/> # endif

Get the Father's Day point, that is, "yaog" in "/home/yaog/test", so that you can search for it in turn. Until "/" is found.

This is not complete yet: the executable file may be mounted and Its mount point information should also be obtained:

# If linux_version_code> = 0x020616 <br/> current-> MM-> MMAP-> vm_file-> f_path.mnt-> mnt_mountpoint-> d_name.name <br/> # else <br/> current-> MM-> MMAP-> vm_file-> f_vfsmnt-> mnt_mountpoint-> d_name.name <br/> # endif

Then we can combine the two parts.

For example, the path of an executable file in the file system is "/yaog/test", and the file system is mounted on the "/home" node of the system.

The path of the executable file is put together by "/home" and "/yaog/test" --> "/home/yaog/test ".

 

3. Unfortunately, the above method has a problem. It works well on some Linux systems, but in some systems, according to the above method, we get "/lib/xxxx. so, rather than the desired "/home/yaog/test ". (/Home/yaog/test calls this so)

 

The final solution goes back to the application layer:

Filp = filp_open ("/proc/(current-> PID)/EXE", 0, 0)

After obtaining the filp, find it again using the method in 2, and then OK.