[libgtop/wip/diskio] Implement disk_rbytes and disk_wbytes for FreeBSD.

[Benoît Dejean <bdejean src gnome org>]

commit 779386cb15e3dba3642ec378cde9fabbb024a4c1
Author: Benoit Dejean <bdejean gmail com>
Date:   Sat May 20 11:34:25 2017 +0200

    Implement disk_rbytes and disk_wbytes for FreeBSD.

 sysdeps/freebsd/procio.c |   39 ++++++++++++++++++++++++++++++++++++++-
 1 files changed, 38 insertions(+), 1 deletions(-)
---
diff --git a/sysdeps/freebsd/procio.c b/sysdeps/freebsd/procio.c
index 27a7a0b..0525a2a 100644
--- a/sysdeps/freebsd/procio.c
+++ b/sysdeps/freebsd/procio.c
@@ -22,8 +22,11 @@
 #include <config.h>
 #include <glibtop.h>
 #include <glibtop/procio.h>
+#include <glibtop/error.h>
+#include <glibtop_suid.h>
 
-static const unsigned long _glibtop_sysdeps_proc_io = 0;
+static const unsigned long _glibtop_sysdeps_proc_io =
+  (1UL << GLIBTOP_PROC_IO_DISK_RBYTES) + (1UL << GLIBTOP_PROC_IO_DISK_WBYTES);
 
 /* Init function. */
 
@@ -40,4 +43,38 @@ glibtop_get_proc_io_p (glibtop *server, glibtop_proc_io *buf,
                         pid_t pid)
 {
        memset (buf, 0, sizeof (glibtop_proc_io));
+
+       struct kinfo_proc *pinfo;
+       int count;
+
+       glibtop_suid_enter (server);
+
+       /* Get the process information */
+       pinfo = kvm_getprocs (server->machine->kd, KERN_PROC_PID, pid, &count);
+       if ((pinfo == NULL) || (count != 1)) {
+               glibtop_warn_io_r (server, "kvm_getprocs (%d)", pid);
+               glibtop_suid_leave (server);
+               return;
+       }
+
+       glibtop_suid_leave (server);
+
+       /* man getrusage
+
+          long ru_inblock;         == block input operations
+          long ru_oublock;         == block output operations
+
+          ru_inblock   the number of times the file system had to perform input.
+          ru_oublock   the number of times the file system had to perform output.
+
+          And then it says 'account only for real IO'.
+
+          But if I write 1MB in a process, I can see ru_oublock increased
+          1024. So it's neither a number of operations or times.
+
+          FIXME: seems the blocksize is 1024 but ...
+       */
+       buf->disk_rbytes = pinfo->ki_rusage.ru_inblock << 10;
+       buf->disk_wbytes = pinfo->ki_rusage.ru_oublock << 10;
+       buf->flags = _glibtop_sysdeps_proc_io;
 }