util/cbfstool: Decouple elogtool from vboot_ref flashrom code

Currently elogtool sub-proccesses flashrom as calling libflashrom
requires a missing function from the previous flashrom release.
Pending a new release of flashrom we must continue to use subprocess.

However the current subprocess wrapper implementation lives in
vboot_reference which is a git sub-module of coreboot. This causes
all sorts of grief keeping a subprocess ABI stable from vboot_reference
when the rest of vboot_reference builds of HEAD of the flashrom tree
(i.e., using unreleased libflashrom functions). In order to not keep
finding ourseleves in a bind between the two separately moving trees
with different build environments, decouple elogtool with its own
mini copy of flashrom subprocess wrapping logic.

Squash in,
 util/cbfstool/elogtool.c: Convert args into struct in flashrom helper

  vboot signatures for flashrom r/w helpers changed in the upstream
  commit bd2971326ee94fc5. Reflect the change here to allow vboot ref
  and coreboot to realign.

BUG=b:207808292,b:231152447
TEST=builds with vboot_ref uprev.

Change-Id: I04925e4d9a44b52e4a6fb6f9cec332cab2c7c725
Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65055
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

util/cbfstool/Makefile.inc

@@ -95,6 +95,7 @@ elogobj += eventlog.o
 elogobj += valstr.o
 elogobj += elog.o
 elogobj += common.o
+elogobj += flashrom.o
 
 include $(top)/util/cbfstool/fpt_formats/Makefile.inc
 cse_fpt_obj :=

util/cbfstool/elogtool.c

@@ -79,15 +79,10 @@ static void usage(char *invoked_as)
 static int elog_read(struct buffer *buffer, const char *filename)
 {
 	if (filename == NULL) {
-		uint8_t *buf;
-		uint32_t buf_size;
-
-		if (flashrom_read(FLASHROM_PROGRAMMER_INTERNAL_AP, ELOG_RW_REGION_NAME,
-				  &buf, &buf_size) != VB2_SUCCESS) {
+		if (flashrom_host_read(buffer, ELOG_RW_REGION_NAME) != 0) {
 			fprintf(stderr, "Could not read RW_ELOG region using flashrom\n");
 			return ELOGTOOL_EXIT_READ_ERROR;
 		}
-		buffer_init(buffer, NULL, buf, buf_size);
 	} else if (buffer_from_file(buffer, filename) != 0) {
 		fprintf(stderr, "Could not read input file: %s\n", filename);
 		return ELOGTOOL_EXIT_READ_ERROR;
@@ -106,11 +101,10 @@ static int elog_read(struct buffer *buffer, const char *filename)
  * If filename is NULL, it saves the buffer using flashrom.
  * Otherwise, it saves the buffer in the given filename.
  */
-static int elog_write(struct buffer *buf, const char *filename)
+static int elog_write(struct buffer *buffer, const char *filename)
 {
 	if (filename == NULL) {
-		if (flashrom_write(FLASHROM_PROGRAMMER_INTERNAL_AP, ELOG_RW_REGION_NAME,
-				   buffer_get(buf), buffer_size(buf)) != VB2_SUCCESS) {
+		if (flashrom_host_write(buffer, ELOG_RW_REGION_NAME) != 0) {
 			fprintf(stderr,
 				"Failed to write to RW_ELOG region using flashrom\n");
 			return ELOGTOOL_EXIT_WRITE_ERROR;
@@ -118,7 +112,7 @@ static int elog_write(struct buffer *buf, const char *filename)
 		return ELOGTOOL_EXIT_SUCCESS;
 	}
 
-	if (buffer_write_file(buf, filename) != 0) {
+	if (buffer_write_file(buffer, filename) != 0) {
 		fprintf(stderr, "Failed to write to file %s\n", filename);
 		return ELOGTOOL_EXIT_WRITE_ERROR;
 	}

util/cbfstool/flashrom.c

@@ -0,0 +1,143 @@
+/* Copyright 2020 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* For strdup */
+#define _POSIX_C_SOURCE 200809L
+#include <fcntl.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "common.h" /* from cbfstool for buffer API. */
+#include "subprocess.h" /* from vboot_reference */
+#include "flashrom.h"
+
+#define FLASHROM_EXEC_NAME "flashrom"
+#define FLASHROM_PROGRAMMER_INTERNAL_AP "host"
+
+/**
+ * Helper to create a temporary file.
+ *
+ * @param path_out	An output pointer for the filename. Caller should free.
+ *
+ * @return 0 on success, -1 for file open error, or -2 for write error.
+ */
+static int create_temp_file(char **path_out)
+{
+	int fd;
+	int rv;
+	char *path;
+	mode_t umask_save;
+
+#if defined(__FreeBSD__)
+#define P_tmpdir "/tmp"
+#endif
+	*path_out = NULL;
+	path = strdup(P_tmpdir "/flashrom.XXXXXX");
+	/* Set the umask before mkstemp for security considerations. */
+	umask_save = umask(077);
+	fd = mkstemp(path);
+	umask(umask_save);
+	if (fd < 0) {
+		rv = -1;
+		goto fail;
+	}
+
+	close(fd);
+	*path_out = path;
+
+	return 0;
+fail:
+	free(path);
+	return rv;
+}
+
+static int run_flashrom(const char *const argv[])
+{
+	int status = subprocess_run(argv, &subprocess_null, &subprocess_null,
+				    &subprocess_null);
+	if (status) {
+		fprintf(stderr, "Flashrom invocation failed (exit status %d):",
+			status);
+		for (const char *const *argp = argv; *argp; argp++)
+			fprintf(stderr, " %s", *argp);
+		fprintf(stderr, "\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+int flashrom_host_read(struct buffer *buffer, const char *region)
+{
+	char *tmpfile;
+	char region_param[PATH_MAX];
+	int rv;
+
+	if (create_temp_file(&tmpfile) != 0)
+		return -1;
+	if (region)
+		snprintf(region_param, sizeof(region_param), "%s:%s", region,
+			 tmpfile);
+	const char *const argv[] = {
+		FLASHROM_EXEC_NAME,
+		"-p",
+		FLASHROM_PROGRAMMER_INTERNAL_AP,
+		"-r",
+		region ? "-i" : tmpfile,
+		region ? region_param : NULL,
+		NULL,
+	};
+	rv = run_flashrom(argv);
+	if (!rv)
+		rv = buffer_from_file(buffer, tmpfile);
+
+	unlink(tmpfile);
+	free(tmpfile);
+
+	return rv;
+}
+
+int flashrom_host_write(struct buffer *buffer, const char *region)
+{
+	char *tmpfile;
+	char region_param[PATH_MAX];
+	int rv;
+
+	if (create_temp_file(&tmpfile) != 0)
+		return -1;
+	if (buffer_write_file(buffer, tmpfile) != 0) {
+		rv = -2;
+		goto fail;
+	}
+
+	if (region)
+		snprintf(region_param, sizeof(region_param), "%s:%s", region,
+			 tmpfile);
+	const char *const argv[] = {
+		FLASHROM_EXEC_NAME,
+		"-p",
+		FLASHROM_PROGRAMMER_INTERNAL_AP,
+		"--noverify-all",
+		"-w",
+		region ? "-i" : tmpfile,
+		region ? region_param : NULL,
+		NULL,
+	};
+
+	rv = run_flashrom(argv);
+
+fail:
+	unlink(tmpfile);
+	free(tmpfile);
+
+	return rv;
+}

util/cbfstool/flashrom.h

@@ -0,0 +1,33 @@
+/* Copyright 2020 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Host utilities to execute flashrom command.
+ */
+
+#include <stdint.h>
+#include "common.h" /* from cbfstool for buffer API. */
+
+/**
+ * Read using flashrom into an allocated buffer.
+ *
+ * @param buffer	The parameter that contains the buffer to use
+ *			in the read operation.
+ * @param region	The name of the fmap region to read, or NULL to
+ *			read the entire flash chip.
+ *
+ * @return 0 on success, or < 0 on error.
+ */
+int flashrom_host_read(struct buffer *buffer, const char *region);
+
+/**
+ * Write using flashrom from a buffer.
+ *
+ * @param buffer	The parameter that contains the buffer to use
+ *			in the write operation.
+ * @param regions	The name of the fmap region to write, or NULL to
+ *			write the entire flash chip.
+ *
+ * @return 0 on success, or < 0 on error.
+ */
+int flashrom_host_write(struct buffer *buffer, const char *region);