gcc 7 is pickier about our sources:
hw/usb/bus.c: In function ‘usb_port_location’:
hw/usb/bus.c:410:66: error: ‘%d’ directive output may be truncated writing
between 1 and 11 bytes into a region of size between 0 and 15
[-Werror=format-truncation=]
snprintf(downstream->path, sizeof(downstream->path), "%s.%d",
^~
hw/usb/bus.c:410:9: note: ‘snprintf’ output between 3 and 28 bytes into a
destination of size 16
snprintf(downstream->path, sizeof(downstream->path), "%s.%d",
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
upstream->path, portnr);
~~~~~~~~~~~~~~~~~~~~~~~
But we know that there are at most 5 levels of USB hubs, with at
most two digits per level; that plus the separating dots means we
use at most 15 bytes (including trailing NUL) of our 16-byte field.
Adding an assertion to show gcc that we checked for truncation is
enough to shut up the false-positive warning.
Inspired by an idea by Dr. David Alan Gilbert <address@hidden>.
---
hw/usb/bus.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/hw/usb/bus.c b/hw/usb/bus.c
index 5939b273b9..d910f849e7 100644
--- a/hw/usb/bus.c
+++ b/hw/usb/bus.c
@@ -407,8 +407,10 @@ void usb_register_companion(const char *masterbus, USBPort
*ports[],
void usb_port_location(USBPort *downstream, USBPort *upstream, int portnr)
{
if (upstream) {
- snprintf(downstream->path, sizeof(downstream->path), "%s.%d",
- upstream->path, portnr);
+ int l = snprintf(downstream->path, sizeof(downstream->path), "%s.%d",
+ upstream->path, portnr);
+ /* Max string is nn.nn.nn.nn.nn, which fits in 16 bytes */
+ assert(l < sizeof(downstream->path));
downstream->hubcount = upstream->hubcount + 1;
} else {
snprintf(downstream->path, sizeof(downstream->path), "%d", portnr);