How to use lsof(List Opened Files) in a C/C++ appl

Question

Is there any way to get all opened sockets using c++? I know the lsof command and this is what I'm looking for, but how to use it in a c++ application?

The idea is to get the FD of an opened socket by its port number and the pid.

Answer 1

check the lsof source?

ftp://lsof.itap.purdue.edu/pub/tools/unix/lsof/

Answer 2

If you don't want to copy/paste or reimplement chunks of the lsof code, and it doesn't build any useful libraries you could leverage, you can still open a pipe to an lsof process and peruse its output.

Answer 3

Just open the files in /proc/net, like /proc/net/tcp, /proc/net/udp, etc. No need to slog through the lsof sources. :)

Answer 4

The lsof command is prepared specifically such that it can be used from other programs including C, see the section: OUTPUT FOR OTHER PROGRAMS of man lsof for more information. For example you can invoke lsof with -F p and it will output the pid of the processes prefixed with 'p':

$ lsof -F p /some/file
p1234
p4321

you can then use popen to execute this commmand in a child process and read from its standard output.