gcc8.1: fix strncpy bounds warnings

These warnings are coming on default Fedora 28 build and probably others using gcc 8.1

../shared.c: In function ‘expand_macro’:
../shared.c:483:3: warning: ‘strncpy’ specified bound depends on the length of the source argument [-Wstringop-overflow=]
   strncpy(name, value, len);
   ^~~~~~~~~~~~~~~~~~~~~~~~~
../shared.c:480:9: note: length computed here
   len = strlen(value);
         ^~~~~~~~~~~~~

strncpy with a computed length via strlen is usually
not the right thing.

../ui-shared.c: In function ‘cgit_repobasename’:
../ui-shared.c:135:2: warning: ‘strncpy’ specified bound 1024 equals destination size [-Wstringop-truncation]
  strncpy(rvbuf, reponame, sizeof(rvbuf));
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

add one char of padding and adjust so the code does the same.

Signed-off-by: Andy Green <andy@warmcat.com>

2 files changed, 5 insertions, 4 deletions

diff --git a/shared.c b/shared.c
index 21ac8f4..477db0a 100644
--- a/shared.c
+++ b/shared.c
@@ -480,7 +480,7 @@ static char *expand_macro(char *name, int maxlength)
 		len = strlen(value);
 		if (len > maxlength)
 			len = maxlength;
-		strncpy(name, value, len);
+		memcpy(name, value, len);
 	}
 	return name + len;
 }
diff --git a/ui-shared.c b/ui-shared.c
index 9d8f66b..6656bd5 100644
--- a/ui-shared.c
+++ b/ui-shared.c
@@ -129,11 +129,12 @@ char *cgit_pageurl(const char *reponame, const char *pagename,
 const char *cgit_repobasename(const char *reponame)
 {
 	/* I assume we don't need to store more than one repo basename */
-	static char rvbuf[1024];
+	static char rvbuf[1025];
 	int p;
 	const char *rv;
-	strncpy(rvbuf, reponame, sizeof(rvbuf));
-	if (rvbuf[sizeof(rvbuf)-1])
+
+	strncpy(rvbuf, reponame, sizeof(rvbuf) - 1);
+	if (rvbuf[sizeof(rvbuf) - 2])
 		die("cgit_repobasename: truncated repository name '%s'", reponame);
 	p = strlen(rvbuf)-1;
 	/* strip trailing slashes */