futility: cmd_update: Access system firmware using external flashrom

To manipulate the firmware contents on device, we need to access the
flash chipset (usually via SPI) on system. The `host_flashrom` provides
a way to call external program "flashrom" for reading and writing
firmware. So the `update_firmware` can now load "system current
firmware" using flashrom.

Note in the future we may want to statically link the flashrom as
library so there won't be external dependency.

BUG=chromium:875551
TEST=make futil; futility update -i IMAGE
     tests/futility/run_test_scripts.sh $(pwd)/build/futility
BRANCH=None

Change-Id: I52f2d4fe4fe4dd660f762a5a75e3367820717e19
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1183650
Reviewed-by: Randall Spangler <rspangler@chromium.org>

2 files changed, 100 insertions, 4 deletions

diff --git a/futility/cmd_update.c b/futility/cmd_update.c
index 5c724731..0ddaa01b 100644
--- a/futility/cmd_update.c
+++ b/futility/cmd_update.c
@@ -16,6 +16,8 @@
 #include "host_misc.h"
 #include "utility.h"
 
+#define RETURN_ON_FAILURE(x) do {int r = (x); if (r) return r;} while (0);
+
 /* FMAP section names. */
 static const char * const FMAP_RO_FRID = "RO_FRID",
 		  * const FMAP_RW_FWID = "RW_FWID",
@@ -27,6 +29,11 @@ static const char * const PROG_HOST = "host",
 		  * const PROG_EC = "ec",
 		  * const PROG_PD = "ec:dev=1";
 
+enum flashrom_ops {
+	FLASHROM_READ,
+	FLASHROM_WRITE,
+};
+
 struct firmware_image {
 	const char *programmer;
 	uint32_t size;
@@ -47,6 +54,64 @@ struct updater_config {
 };
 
 /*
+ * A helper function to invoke flashrom(8) command.
+ * Returns 0 if success, non-zero if error.
+ */
+static int host_flashrom(enum flashrom_ops op, const char *image_path,
+			 const char *programmer, int verbose,
+			 const char *section_name)
+{
+	char *command;
+	const char *op_cmd, *dash_i = "-i", *postfix = "";
+	int r;
+
+	if (debugging_enabled)
+		verbose = 1;
+
+	if (!verbose)
+		postfix = " >/dev/null 2>&1";
+
+	if (!section_name || !*section_name) {
+		dash_i = "";
+		section_name = "";
+	}
+
+	switch (op) {
+	case FLASHROM_READ:
+		op_cmd = "-r";
+		assert(image_path);
+		break;
+
+	case FLASHROM_WRITE:
+		op_cmd = "-w";
+		assert(image_path);
+		break;
+
+	default:
+		assert(0);
+		return -1;
+	}
+
+	/* TODO(hungte) In future we should link with flashrom directly. */
+	r = asprintf(&command, "flashrom %s %s -p %s %s %s %s", op_cmd,
+		     image_path, programmer, dash_i, section_name, postfix);
+
+	if (r == -1) {
+		/* `command` will be not available. */
+		Error("%s: Cannot allocate memory for command to execute.\n",
+		      __FUNCTION__);
+		return -1;
+	}
+
+	if (verbose)
+		printf("Executing: %s\n", command);
+
+	r = system(command);
+	free(command);
+	return r;
+}
+
+/*
  * Finds a firmware section by given name in the firmware image.
  * If successful, return zero and *section argument contains the address and
  * size of the section; otherwise failure.
@@ -147,6 +212,21 @@ static int load_image(const char *file_name, struct firmware_image *image)
 }
 
 /*
+ * Loads the active system firmware image (usually from SPI flash chip).
+ * Returns 0 if success, non-zero if error.
+ */
+static int load_system_image(struct updater_config *cfg,
+			     struct firmware_image *image)
+{
+	/* TODO(hungte) replace by mkstemp */
+	const char *tmp_file = "/tmp/.fwupdate.read";
+
+	RETURN_ON_FAILURE(host_flashrom(
+			FLASHROM_READ, tmp_file, image->programmer, 0, NULL));
+	return load_image(tmp_file, image);
+}
+
+/*
  * Frees the allocated resource from a firmware image object.
  */
 static void free_image(struct firmware_image *image)
@@ -162,12 +242,14 @@ static void free_image(struct firmware_image *image)
 enum updater_error_codes {
 	UPDATE_ERR_DONE,
 	UPDATE_ERR_NO_IMAGE,
+	UPDATE_ERR_SYSTEM_IMAGE,
 	UPDATE_ERR_UNKNOWN,
 };
 
 static const char * const updater_error_messages[] = {
 	[UPDATE_ERR_DONE] = "Done (no error)",
 	[UPDATE_ERR_NO_IMAGE] = "No image to update; try specify with -i.",
+	[UPDATE_ERR_SYSTEM_IMAGE] = "Cannot load system active firmware.",
 	[UPDATE_ERR_UNKNOWN] = "Unknown error.",
 };
 
@@ -177,7 +259,8 @@ static const char * const updater_error_messages[] = {
  */
 static enum updater_error_codes update_firmware(struct updater_config *cfg)
 {
-	struct firmware_image *image_to = &cfg->image;
+	struct firmware_image *image_from = &cfg->image_current,
+			      *image_to = &cfg->image;
 	if (!image_to->data)
 		return UPDATE_ERR_NO_IMAGE;
 
@@ -185,6 +268,19 @@ static enum updater_error_codes update_firmware(struct updater_config *cfg)
 	       image_to->file_name, image_to->ro_version,
 	       image_to->rw_version_a, image_to->rw_version_b);
 
+	if (!image_from->data) {
+		/*
+		 * TODO(hungte) Read only RO_SECTION, VBLOCK_A, VBLOCK_B,
+		 * RO_VPD, RW_VPD, RW_NVRAM, RW_LEGACY.
+		 */
+		printf("Loading current system firmware...\n");
+		if (load_system_image(cfg, image_from) != 0)
+			return UPDATE_ERR_SYSTEM_IMAGE;
+	}
+	printf(">> Current system: %s (RO:%s, RW/A:%s, RW/B:%s).\n",
+	       image_from->file_name, image_from->ro_version,
+	       image_from->rw_version_a, image_from->rw_version_b);
+
 	return UPDATE_ERR_DONE;
 }
 
diff --git a/tests/futility/test_update.sh b/tests/futility/test_update.sh
index c7ade51a..aaf46904 100755
--- a/tests/futility/test_update.sh
+++ b/tests/futility/test_update.sh
@@ -16,6 +16,6 @@ cd "$OUTDIR"
 set -o pipefail
 
 # Test command execution.
-"${FUTILITY}" update -i "${LINK_BIOS}" |
-	grep "RO:${LINK_VERSION}, RW/A:${LINK_VERSION}, RW/B:${LINK_VERSION}"
-"${FUTILITY}" --debug update -i "${LINK_BIOS}" | grep 8388608
+
+# The updater is now currently always loading system firmware using flashrom(8)
+# and can't be tested until an emulation interface is implemented.