Re: [PATCH v3] hw/core/qdev-properties-system: Rewrite set_pci_host_devaddr using GLib

["Alex Bennée" <alex.bennee@linaro.org>]

Philippe Mathieu-Daudé <philmd@redhat.com> writes:

> set_pci_host_devaddr() is hard to follow, thus bug-prone.
>
> For example, a bug was introduced in commit bccb20c49df, as
> the same line might be used to parse a bus (up to 0xff) or
> a slot (up to 0x1f).
>
> Instead of making things worst, rewrite using g_strsplit().

This no longer applies to my tip of tree but in general I'm a fan. Do we
have any unit tests for the qdev parsing? I couldn't see any but I'm not
sure if the generic QOM tests would exercise this code.

Generally when re-writing a parser it's nice to have a unit test just so
you can check you've covered all the corner cases (witness the number of
iterations the dfilter logic took to get right :-/).

>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> v3: Rebased
> v2: Free g_strsplit() with g_auto(GStrv) (Daniel)
> ---
>  hw/core/qdev-properties-system.c | 62 ++++++++++++++------------------
>  1 file changed, 27 insertions(+), 35 deletions(-)
>
> diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
> index 9d80a07d26f..79408e32289 100644
> --- a/hw/core/qdev-properties-system.c
> +++ b/hw/core/qdev-properties-system.c
> @@ -857,11 +857,11 @@ static void set_pci_host_devaddr(Object *obj, Visitor *v, const char *name,
>      DeviceState *dev = DEVICE(obj);
>      Property *prop = opaque;
>      PCIHostDeviceAddress *addr = qdev_get_prop_ptr(dev, prop);
> -    char *str, *p;
> -    char *e;
> +    g_autofree char *str = NULL;
> +    g_auto(GStrv) col_s0 = NULL;
> +    g_auto(GStrv) dot_s = NULL;
> +    char **col_s;
>      unsigned long val;
> -    unsigned long dom = 0, bus = 0;
> -    unsigned int slot = 0, func = 0;
>  
>      if (dev->realized) {
>          qdev_prop_set_after_realize(dev, name, errp);
> @@ -872,58 +872,50 @@ static void set_pci_host_devaddr(Object *obj, Visitor *v, const char *name,
>          return;
>      }
>  
> -    p = str;
> -    val = strtoul(p, &e, 16);
> -    if (e == p || *e != ':') {
> +    col_s = col_s0 = g_strsplit(str, ":", 3);
> +    if (!col_s || !col_s[0] || !col_s[1]) {

I'm not sure you want max_tokens 3 because 1:2:3:4 would end up with the
malformed ["1", "2", "3:4"]. You could just make your test:

  cols_s = g_strsplit(str, ":", -1);
  if (!cols_s || g_strv_length(cols_s) != 3) {
    error_set_from_qdev_prop_error(errp, EINVAL, dev, prop, str);  
    return;
  }

>          goto inval;
>      }
> -    bus = val;
>  
> -    p = e + 1;
> -    val = strtoul(p, &e, 16);
> -    if (e == p) {
> -        goto inval;
> -    }
> -    if (*e == ':') {
> -        dom = bus;
> -        bus = val;
> -        p = e + 1;
> -        val = strtoul(p, &e, 16);
> -        if (e == p) {
> +    /* domain */
> +    if (col_s[2]) {
> +        if (qemu_strtoul(col_s[0], NULL, 16, &val) < 0 || val > 0xffff) {
>              goto inval;
>          }
> +        addr->domain = val;
> +        col_s++;
> +    } else {
> +        addr->domain = 0;
>      }
> -    slot = val;

Hmm ok PCI ids are more complex than I knew. Maybe the test above needs
to be:

  cols_s = g_strsplit(str, ":", -1);
  cols_l = g_strv_length(cols_s);
  if (!cols_s || !(cols_l == 2 || cols_l ==3)) {
    error_set_from_qdev_prop_error(errp, EINVAL, dev, prop, str);  
    return;
  }
  

>  
> -    if (*e != '.') {
> +    /* bus */
> +    if (qemu_strtoul(col_s[0], NULL, 16, &val) < 0 || val > 0xff) {
>          goto inval;
>      }
> -    p = e + 1;
> -    val = strtoul(p, &e, 10);
> -    if (e == p) {
> -        goto inval;
> -    }
> -    func = val;
> +    addr->bus = val;
>  
> -    if (dom > 0xffff || bus > 0xff || slot > 0x1f || func > 7) {
> +    /* <slot>.<func> */
> +    dot_s = g_strsplit(col_s[1], ".", 2);
> +    if (!dot_s || !dot_s[0] || !dot_s[1]) {
>          goto inval;
>      }

I think there is a similar length validation needed here.

>  
> -    if (*e) {
> +    /* slot */
> +    if (qemu_strtoul(dot_s[0], NULL, 16, &val) < 0 || val > 0x1f) {
>          goto inval;
>      }
> +    addr->slot = val;
>  
> -    addr->domain = dom;
> -    addr->bus = bus;
> -    addr->slot = slot;
> -    addr->function = func;
> +    /* func */
> +    if (qemu_strtoul(dot_s[1], NULL, 10, &val) < 0 || val > 7) {
> +        goto inval;
> +    }
> +    addr->function = val;
>  
> -    g_free(str);
>      return;
>  
>  inval:
>      error_set_from_qdev_prop_error(errp, EINVAL, dev, prop, str);
> -    g_free(str);
>  }
>  
>  const PropertyInfo qdev_prop_pci_host_devaddr = {


-- 
Alex Bennée