https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96951
Bug ID: 96951
Summary: strncpy truncation warning does not recognize
truncation check
Product: gcc
Version: 10.2.1
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: fw at gcc dot gnu.org
Target Milestone: ---
This code example produces a warning:
#include <string.h>
struct buffer {
char string[10];
};
int
f (struct buffer *p, const char *s)
{
strncpy (p->string, s, sizeof (p->string));
if (p->string[sizeof (p->string) - 1] != '\0')
return -1;
return 0;
}
t.c: In function ‘f’:
t.c:10:3: warning: ‘strncpy’ specified bound 10 equals destination size
[-Wstringop-truncation]
10 | strncpy (p->string, s, sizeof (p->string));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
There is an explicit truncation check, however, so the warning does not apply.
Suggested by Kim Barrett here:
https://mail.openjdk.java.net/pipermail/hotspot-dev/2020-September/042890.html
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