util/nvmutil: use own strnlen function: xstrxlen

strnlen is not available on some older systems,
so now we provide our own portable version.

this version also aborts on NULL input, unlike
the standard function.

this version also does not permit empty strings.

this version also does not permit unterminated
strings.

Signed-off-by: Leah Rowe <leah@libreboot.org>

1 files changed, 32 insertions, 1 deletions

diff --git a/util/nvmutil/nvmutil.c b/util/nvmutil/nvmutil.c
index 34bca222..ed53ea25 100644
--- a/util/nvmutil/nvmutil.c
+++ b/util/nvmutil/nvmutil.c
@@ -74,6 +74,7 @@ static off_t gbe_x_offset(size_t part, const char *f_op,
 static void set_part_modified(size_t p);
 static void check_part_num(size_t p);
 static void usage(void);
+static size_t xstrxlen(const char *scmp, size_t maxlen);
 static void err(int nvm_errval, const char *msg, ...);
 static const char *getnvmprogname(void);
 static void set_err(int errval);
@@ -215,6 +216,9 @@ static size_t cmd_index = CMD_NULL;
 int
 main(int argc, char *argv[])
 {
+#ifdef HAVE_STRNLEN
+	err(1, "TEST");
+#endif
 	argv0 = argv[0];
 	if (argc < 2)
 		usage();
@@ -348,7 +352,7 @@ sanitize_command_index(size_t c)
 	if (*command[c].str == '\0')
 		err(ECANCELED, "cmd index %zu: empty str", c);
 
-	if (strnlen(command[c].str, MAX_CMD_LEN + 1) >
+	if (xstrxlen(command[c].str, MAX_CMD_LEN + 1) >
 	    MAX_CMD_LEN) {
 		err(ECANCELED, "cmd index %zu: str too long: %s",
 		    c, command[c].str);
@@ -1087,6 +1091,33 @@ usage(void)
 	err(ECANCELED, "Too few arguments");
 }
 
+/*
+ * strnlen() but aborts on NULL input, and empty strings.
+ * Our version also prohibits unterminated strings.
+ * strnlen() was standardized in POSIX.1-2008 and is not
+ * available on some older systems, so we provide our own.
+ */
+static size_t
+xstrxlen(const char *scmp, size_t maxlen)
+{
+	size_t xstr_index;
+
+	if (scmp == NULL)
+		err(EINVAL, "NULL input to xstrxlen");
+
+	if (*scmp == '\0')
+		err(EINVAL, "Empty string in xstrxlen");
+
+	for (xstr_index = 0;
+	    xstr_index < maxlen && scmp[xstr_index] != '\0';
+	    xstr_index++);
+
+	if (xstr_index == maxlen)
+		err(EINVAL, "Unterminated string in xstrxlen");
+
+	return xstr_index;
+}
+
 static void
 err(int nvm_errval, const char *msg, ...)
 {