1 files changed, 187 insertions, 0 deletions
diff --git a/util/nvmutil/lib/string.c b/util/nvmutil/lib/string.c
new file mode 100644
index 00000000..529dbf59
--- /dev/null
+++ b/util/nvmutil/lib/string.c
@@ -0,0 +1,187 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (c) 2026 Leah Rowe <leah@libreboot.org>
+ *
+ * String handling.
+ */
+
+#ifdef __OpenBSD__
+#include <sys/param.h>
+#endif
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "../include/common.h"
+
+/*
+ * Portable strcmp() but blocks NULL/empty/unterminated
+ * strings. Even stricter than strncmp().
+ */
+int
+xstrxcmp(const char *a, const char *b, unsigned long maxlen)
+{
+	unsigned long i;
+
+	if (a == NULL || b == NULL)
+		err(EINVAL, "NULL input to xstrxcmp");
+
+	if (*a == '\0' || *b == '\0')
+		err(EINVAL, "Empty string in xstrxcmp");
+
+	for (i = 0; i < maxlen; i++) {
+
+		unsigned char ac = (unsigned char)a[i];
+		unsigned char bc = (unsigned char)b[i];
+
+		if (ac == '\0' || bc == '\0') {
+			if (ac == bc)
+				return 0;
+			return ac - bc;
+		}
+
+		if (ac != bc)
+			return ac - bc;
+	}
+
+	/*
+	 * We reached maxlen, so assume unterminated string.
+	 */
+	err(EINVAL, "Unterminated string in xstrxcmp");
+
+	/*
+	 * Should never reach here. This keeps compilers happy.
+	 */
+	errno = EINVAL;
+	return -1;
+}
+
+/*
+ * 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.
+ */
+unsigned long
+xstrxlen(const char *scmp, unsigned long maxlen)
+{
+	unsigned long 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;
+}
+
+void
+err(int nvm_errval, const char *msg, ...)
+{
+	struct xstate *x = xstatus();
+
+	va_list args;
+
+	if (errno == 0)
+		errno = nvm_errval;
+	if (!errno)
+		errno = ECANCELED;
+
+	(void)exit_cleanup();
+
+	if (x != NULL)
+		fprintf(stderr, "%s: ", getnvmprogname());
+
+	va_start(args, msg);
+	vfprintf(stderr, msg, args);
+	va_end(args);
+
+	fprintf(stderr, ": %s\n", strerror(errno));
+
+	exit(EXIT_FAILURE);
+}
+
+const char *
+getnvmprogname(void)
+{
+	struct xstate *x = xstatus();
+
+	const char *p;
+	static char fallback[] = "nvmutil";
+
+	char *rval = fallback;
+
+	if (x != NULL) {
+		if (x->argv0 == NULL || *x->argv0 == '\0')
+			return "";
+
+		rval = x->argv0;
+	}
+
+	p = x_c_strrchr(rval, '/');
+
+	if (p)
+		return p + 1;
+	else
+		return rval;
+}
+
+char *
+x_c_strrchr(const char *s, int c)
+{
+	const char *p = NULL;
+
+	while (*s) {
+		if (*s == (char)c)
+			p = s;
+		s++;
+	}
+
+	if (c == '\0')
+		return (char *)s;
+
+	return (char *)p;
+}
+
+void *
+x_v_memcpy(void *dst, const void *src, unsigned long n)
+{
+	unsigned char *d = (unsigned char *)dst;
+	const unsigned char *s = (const unsigned char *)src;
+
+	while (n--)
+		*d++ = *s++;
+
+	return dst;
+}
+
+int
+x_i_memcmp(const void *a, const void *b, unsigned long n)
+{
+	const unsigned char *pa = (const unsigned char *)a;
+	const unsigned char *pb = (const unsigned char *)b;
+
+	for ( ; n--; ++pa, ++pb)
+		if (*pa != *pb)
+			return *pa - *pb;
+
+	return 0;
+}