util: add smmstoretool for editing SMMSTORE

Offline SMMSTORE variable modification tool.  Can be used to
pre-configure ROM image or debug EFI state stored in a dump.

Change-Id: I6c1c06f1d0c39c13b5be76a3070f09b715aca6e0
Signed-off-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79080
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Michał Żygowski <michal.zygowski@3mdeb.com>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

util/smmstoretool/utils.c

@@ -0,0 +1,111 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "utils.h"
+
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <errno.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+void *xmalloc(size_t size)
+{
+	void *p = malloc(size);
+	if (p == NULL) {
+		fprintf(stderr, "Failed to allocate memory\n");
+		abort();
+	}
+	return p;
+}
+
+char *to_chars(const CHAR16 uchars[], size_t size)
+{
+	char *chars = xmalloc(size / 2 + 1);
+
+	const CHAR16 *from = uchars;
+	char *to = chars;
+	while (*from != 0) {
+		CHAR16 uc = *from++;
+		if (uc < CHAR_MAX)
+			*to++ = uc;
+		else
+			*to++ = '?';
+	}
+
+	// In case there was no terminating NUL.
+	if (to != chars && to[-1] != '\0')
+		*to = '\0';
+
+	return chars;
+}
+
+CHAR16 *to_uchars(const char chars[], size_t *size)
+{
+	*size = (strlen(chars) + 1) * 2;
+	CHAR16 *uchars = xmalloc(*size);
+
+	const char *from = chars;
+	CHAR16 *to = uchars;
+	while (*from != '\0')
+		*to++ = *from++;
+	*to = 0;
+
+	return uchars;
+}
+
+bool str_eq(const char lhs[], const char rhs[])
+{
+	return strcmp(lhs, rhs) == 0;
+}
+
+struct mem_range_t map_file(const char path[], bool rw)
+{
+	struct mem_range_t range = {0};
+
+	int open_flags = rw ? O_RDWR : O_RDONLY;
+	int mmap_flags = rw ? PROT_READ | PROT_WRITE : PROT_READ;
+
+	int fd = open(path, open_flags);
+	if (fd == -1) {
+		fprintf(stderr, "Failed to open(): %s\n", strerror(errno));
+		return range;
+	}
+
+	struct stat stat_buf;
+	if (fstat(fd, &stat_buf) != 0) {
+		(void)close(fd);
+		fprintf(stderr, "Failed to fstat(): %s\n", strerror(errno));
+		return range;
+	}
+
+	if (stat_buf.st_size == 0) {
+		(void)close(fd);
+		fprintf(stderr, "Can't map an empty \"%s\" file\n", path);
+		return range;
+	}
+
+	uint8_t *mem = mmap(/*addr=*/NULL, stat_buf.st_size, mmap_flags,
+			    MAP_SHARED | MAP_POPULATE, fd, /*offset=*/0);
+	(void)close(fd);
+	if (mem == MAP_FAILED) {
+		fprintf(stderr, "Failed to mmap(): %s\n", strerror(errno));
+		return range;
+	}
+
+	range.start = mem;
+	range.length = stat_buf.st_size;
+	return range;
+}
+
+void unmap_file(struct mem_range_t store)
+{
+	if (munmap(store.start, store.length) != 0)
+		fprintf(stderr, "Failed to munmap(): %s\n", strerror(errno));
+}