[PATCH v2 2/2] Use virProcessGetStat

[Daniel P. Berrangé]

On Sun, Nov 21, 2021 at 12:04:26AM +0100, Martin Kletzander wrote:
> This eliminates one incorrect parsing implementation.

Please explain what was being done wrongly / what was the
effect of the bug ?

> 
> Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
> ---
>  src/qemu/qemu_driver.c | 33 ++++++-----------------------
>  src/util/virprocess.c  | 48 ++++++------------------------------------
>  2 files changed, 12 insertions(+), 69 deletions(-)
> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index d954635dde2a..0468d6aaf314 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -1399,36 +1399,17 @@ qemuGetSchedInfo(unsigned long long *cpuWait,
>  
>  static int
>  qemuGetProcessInfo(unsigned long long *cpuTime, int *lastCpu, long *vm_rss,
> -                   pid_t pid, int tid)
> +                   pid_t pid, pid_t tid)
>  {
> -    g_autofree char *proc = NULL;
> -    FILE *pidinfo;
> +    g_auto(GStrv) proc_stat = virProcessGetStat(pid, tid);
>      unsigned long long usertime = 0, systime = 0;
>      long rss = 0;
>      int cpu = 0;
>  
> -    /* In general, we cannot assume pid_t fits in int; but /proc parsing
> -     * is specific to Linux where int works fine.  */
> -    if (tid)
> -        proc = g_strdup_printf("/proc/%d/task/%d/stat", (int)pid, tid);
> -    else
> -        proc = g_strdup_printf("/proc/%d/stat", (int)pid);
> -    if (!proc)
> -        return -1;
> -
> -    pidinfo = fopen(proc, "r");
> -
> -    /* See 'man proc' for information about what all these fields are. We're
> -     * only interested in a very few of them */
> -    if (!pidinfo ||
> -        fscanf(pidinfo,
> -               /* pid -> stime */
> -               "%*d (%*[^)]) %*c %*d %*d %*d %*d %*d %*u %*u %*u %*u %*u %llu %llu"
> -               /* cutime -> endcode */
> -               "%*d %*d %*d %*d %*d %*d %*u %*u %ld %*u %*u %*u"
> -               /* startstack -> processor */
> -               "%*u %*u %*u %*u %*u %*u %*u %*u %*u %*u %*d %d",
> -               &usertime, &systime, &rss, &cpu) != 4) {
> +    if (virStrToLong_ullp(proc_stat[13], NULL, 10, &usertime) < 0 ||
> +        virStrToLong_ullp(proc_stat[14], NULL, 10, &systime) < 0 ||
> +        virStrToLong_l(proc_stat[23], NULL, 10, &rss) < 0 ||
> +        virStrToLong_i(proc_stat[38], NULL, 10, &cpu) < 0) {

Since you're adding a formal API, I think we'd benefit from
constants for these array indexes in virprocess.h


Regards,
Daniel
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