util/mkhtemp: new utility (hardened mktemp)

part of the same code library as nvmutil.

as part of this, i renamed util/nvmutil
to util/libreboot-utils/ because it is
now a multi-utility codebase.

this is more efficient, since i also wish
to use mkhtemp (function) in nvmutil.

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

1 files changed, 68 insertions, 0 deletions

diff --git a/util/libreboot-utils/lib/word.c b/util/libreboot-utils/lib/word.c
new file mode 100644
index 00000000..f84dae6a
--- /dev/null
+++ b/util/libreboot-utils/lib/word.c
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: MIT
+ * Copyright (c) 2022-2026 Leah Rowe <leah@libreboot.org>
+ *
+ * Manipulate Intel GbE NVM words, which are 16-bit little
+ * endian in the files (MAC address words are big endian).
+ */
+
+#include <sys/types.h>
+
+#include <errno.h>
+#include <stddef.h>
+
+#include "../include/common.h"
+
+unsigned short
+nvm_word(size_t pos16, size_t p)
+{
+	struct xstate *x = xstatus();
+	struct xfile *f = &x->f;
+
+	size_t pos;
+
+	check_nvm_bound(pos16, p);
+	pos = (pos16 << 1) + (p * GBE_PART_SIZE);
+
+	return (unsigned short)f->buf[pos] |
+	    ((unsigned short)f->buf[pos + 1] << 8);
+}
+
+void
+set_nvm_word(size_t pos16, size_t p, unsigned short val16)
+{
+	struct xstate *x = xstatus();
+	struct xfile *f = &x->f;
+
+	size_t pos;
+
+	check_nvm_bound(pos16, p);
+	pos = (pos16 << 1) + (p * GBE_PART_SIZE);
+
+	f->buf[pos] = (unsigned char)(val16 & 0xff);
+	f->buf[pos + 1] = (unsigned char)(val16 >> 8);
+
+	set_part_modified(p);
+}
+
+void
+set_part_modified(size_t p)
+{
+	struct xstate *x = xstatus();
+	struct xfile *f = &x->f;
+
+	check_bin(p, "part number");
+	f->part_modified[p] = 1;
+}
+
+void
+check_nvm_bound(size_t c, size_t p)
+{
+	/* Block out of bound NVM access
+	 */
+
+	check_bin(p, "part number");
+
+	if (c >= NVM_WORDS)
+		err(ECANCELED, "check_nvm_bound: out of bounds %lu",
+		    (size_t)c);
+}