[nft PATCH 2/2] nfnl_osf: Silence string truncation gcc warnings

[Phil Sutter]

Albeit a bit too enthusiastic, gcc is right in that these strings may be
truncated since the destination buffer is smaller than the source one.
Get rid of the warnings (and the potential problem) by specifying a
string "precision" of one character less than the destination. This
ensures a terminating nul-character may be written as well.

Fixes: af00174af3ef4 ("src: osf: import nfnl_osf.c to load osf fingerprints")
Signed-off-by: Phil Sutter <p...@nwl.cc>
---
 src/nfnl_osf.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/nfnl_osf.c b/src/nfnl_osf.c
index be3fd8100b665..bed9ba64b65c6 100644
--- a/src/nfnl_osf.c
+++ b/src/nfnl_osf.c
@@ -289,32 +289,34 @@ static int osf_load_line(char *buffer, int len, int del,
        pend = nf_osf_strchr(pbeg, OSFPDEL);
        if (pend) {
                *pend = '\0';
-               cnt = snprintf(obuf, sizeof(obuf), "%s,", pbeg);
+               i = sizeof(obuf);
+               cnt = snprintf(obuf, i, "%.*s,", i - 2, pbeg);
                pbeg = pend + 1;
        }
 
        pend = nf_osf_strchr(pbeg, OSFPDEL);
        if (pend) {
                *pend = '\0';
+               i = sizeof(f.genre);
                if (pbeg[0] == '@' || pbeg[0] == '*')
-                       cnt = snprintf(f.genre, sizeof(f.genre), "%s", pbeg + 
1);
-               else
-                       cnt = snprintf(f.genre, sizeof(f.genre), "%s", pbeg);
+                       pbeg++;
+               cnt = snprintf(f.genre, i, "%.*s", i - 1, pbeg + 1);
                pbeg = pend + 1;
        }
 
        pend = nf_osf_strchr(pbeg, OSFPDEL);
        if (pend) {
                *pend = '\0';
-               cnt = snprintf(f.version, sizeof(f.version), "%s", pbeg);
+               i = sizeof(f.version);
+               cnt = snprintf(f.version, i, "%.*s", i - 1, pbeg);
                pbeg = pend + 1;
        }
 
        pend = nf_osf_strchr(pbeg, OSFPDEL);
        if (pend) {
                *pend = '\0';
-               cnt =
-                   snprintf(f.subtype, sizeof(f.subtype), "%s", pbeg);
+               i = sizeof(f.subtype);
+               cnt = snprintf(f.subtype, i, "%.*s", i - 1, pbeg);
                pbeg = pend + 1;
        }
 
-- 
2.22.0