Unix system call for file directories

[paulsowden]

Is there a system call to check whether a specified directory is a decendent to another directory? I'm moving around a directory using chdir and i need to make sure i stay within the realms of a particular sub tree. Any ideas?

Cheers
Paul

 

[xwb]

There are directory primitives opendir, readdir and closedir. If you traverse them by either going down the children or going to "..", you could find out if one is the child of another.

 

[Salem]

Use the realpath() function

http://nodevice.com/sections/ManIndex/man1306.html

Then just strncmp() the result with the common root directory which you have

If your common root is also a mount point, then you could just check the st_dev field as returned by the stat() function.