Fix -Wstringop-truncation warnings in safe_strncpy()

In function ‘safe_strncpy’,
    inlined from ‘set_utmpx’ at sessreg.c:540:3,
    inlined from ‘main’ at sessreg.c:357:2:
sessreg.c:204:11: warning: ‘strncpy’ specified bound 32 equals destination size [-Wstringop-truncation]
  204 |     (void)strncpy(dest, src, n);
      |           ^~~~~~~~~~~~~~~~~~~~~
In function ‘safe_strncpy’,
    inlined from ‘set_utmpx’ at sessreg.c:530:4,
    inlined from ‘main’ at sessreg.c:357:2:
sessreg.c:204:11: warning: ‘strncpy’ specified bound 32 equals destination size [-Wstringop-truncation]
  204 |     (void)strncpy(dest, src, n);
      |           ^~~~~~~~~~~~~~~~~~~~~
In function ‘safe_strncpy’,
    inlined from ‘set_utmpx’ at sessreg.c:532:3,
    inlined from ‘main’ at sessreg.c:357:2:
sessreg.c:204:11: warning: ‘strncpy’ specified bound 257 equals destination size [-Wstringop-truncation]
  204 |     (void)strncpy(dest, src, n);
      |           ^~~~~~~~~~~~~~~~~~~~~
In function ‘safe_strncpy’,
    inlined from ‘set_utmpx’ at sessreg.c:540:3,
    inlined from ‘main’ at sessreg.c:357:2:
sessreg.c:204:11: warning: ‘strncpy’ specified bound 32 equals destination size [-Wstringop-truncation]
  204 |     (void)strncpy(dest, src, n);
      |           ^~~~~~~~~~~~~~~~~~~~~
In function ‘safe_strncpy’,
    inlined from ‘main’ at sessreg.c:423:5:
sessreg.c:204:11: warning: ‘strncpy’ specified bound 8 equals destination size [-Wstringop-truncation]
  204 |     (void)strncpy(dest, src, n);
      |           ^~~~~~~~~~~~~~~~~~~~~
In function ‘safe_strncpy’,
    inlined from ‘main’ at sessreg.c:425:5:
sessreg.c:204:11: warning: ‘strncpy’ specified bound 16 equals destination size [-Wstringop-truncation]
  204 |     (void)strncpy(dest, src, n);
      |           ^~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/sessreg.c b/sessreg.c
index c574f6e..d39ac74 100644
--- a/sessreg.c
+++ b/sessreg.c
@@ -201,9 +201,10 @@ sysnerr (int x, const char *s)
 static void
 safe_strncpy(char *dest, const char *src, size_t n)
 {
-    (void)strncpy(dest, src, n);
-    if (n > 0)
+    if (n > 0) {
+        strncpy(dest, src, n - 1);
         dest[n - 1] = '\0';
+    }
 }
 
 int