Unix Password

This is a simple C library with OCaml bindings to support updating Unix account passwords in /etc/passwd and /etc/shadow. It is not meant to support other operations, like creating or deleting accounts. For this you might be interested in opasswd which exposed the complete C API for password handling to OCaml.

Be aware that updating password entries requires root privileges. So update functions will fail unless called with root privileges.

OCaml Code

The OCaml code lives in directory src/ and provides simple bindings for the underlying C functions.

C Code

The C code lives in directory c/ and contains a Makefile that is not used by the build process for OCaml bindings but was used during development of the C code.

Command Line Interface

The Makefile in directory c/ builds a small binary for tests. This is especially useful for debugging purposes with GDB.

$ cd c
$ make
$ ./unixpwd root
root: x
/etc/passwd: root: x
can't find shadow entry for root: Permission denied

$ ./unixpwd | head
root:x:0:0:root:/root
daemon:x:1:1:daemon:/usr/sbin
bin:x:2:2:bin:/bin
sys:x:3:3:sys:/dev
sync:x:4:65534:sync:/bin
games:x:5:60:games:/usr/games
man:x:6:12:man:/var/cache/man
lp:x:7:7:lp:/var/spool/lpd
mail:x:8:8:mail:/var/mail
news:x:9:9:news:/var/spool/news

Testing

Directory test/ contains a small OCaml program that reads and updates password entries. Since it needs to be run as root and uses the system's password database, it is not run automatically. It is configures to update the account unixpwd that you might want to create for this purpose.

Known Issues

The Makefile in the c/ directory contains support for running valgrind to find memory leaks. Valgrind reports some reachable memory at exit. As far as I can tell, this is related to memory allocated by libc for /etc/nsswitch.

• getpwnam_r memory leak