It may shorten the code a bit as the following pattern:

  VIR_STRNDUP(dst, src, cond ? n : strlen(src))

is used on several places among our code. However, we can
move the strlen into virStrndup and thus write just:

  VIR_STRNDUP(dst, src, cond ? n : -1)

Since PIDs can be reused, polkit prefers to be given
a (PID,start time) pair. If given a PID on its own,
it will attempt to lookup the start time in /proc/pid/stat,
though this is subject to races.

It is safer if the client app resolves the PID start
time itself, because as long as the app has the client
socket open, the client PID won't be reused.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

While reviewing proposed VIR_STRDUP conversions, I've already noticed
several places that do:

if (str && VIR_STRDUP(dest, str) < 0)

which can be simplified by allowing str to be NULL (something that
strdup() doesn't allow).  Meanwhile, code that wants to ensure a
non-NULL dest regardless of the source can check for <= 0.

Also, make it part of the VIR_STRDUP contract that macro arguments
are evaluated exactly once.

* src/util/virstring.h (VIR_STRDUP, VIR_STRDUP_QUIET, VIR_STRNDUP)
(VIR_STRNDUP_QUIET): Improve contract.
* src/util/virstring.c (virStrdup, virStrndup): Change return
conventions.
* docs/hacking.html.in: Document this.
* HACKING: Regenerate.
Signed-off-by: NEric Blake <eblake@redhat.com>

The code adaptation is not done right now, but in subsequent patches.
Hence I am not implementing syntax-check rule as it would break
compilation. Developers are strongly advised to use these new macros.
They are similar to VIR_ALLOC() logic: VIR_STRDUP(dst, src) returns zero
on success, -1 otherwise. In case you don't want to report OOM error,
use the _QUIET variant of a macro.

The source code base needs to be adapted as well. Some files
include virutil.h just for the string related functions (here,
the include is substituted to match the new file), some include
virutil.h without any need (here, the include is removed), and
some require both.

Signed-off-by: NStefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: NCorey Bryant <coreyb@linux.vnet.ibm.com>
Tested-by: NCorey Bryant <coreyb@linux.vnet.ibm.com>

Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

This introduces a few new APIs for dealing with strings.
One to split a char * into a char **, another to join a
char ** into a char *, and finally one to free a char **

There is a simple test suite to validate the edge cases
too. No more need to use the horrible strtok_r() API,
or hand-written code for splitting strings.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>