futility: updater: Use flashrom dummy programmer to implement --emulate

futility update --emulate and flashrom's dummy programmer serve similar
purposes - both provide support for using a file instead of a real ROM.
The current --emulate implementation involves special-casing before
interacting with flashrom and pre-filling in the current image contents;
an appropriately-configured dummy programmer and unmodified flashrom
interactions could accomplish the same outcome with a more centralised
handling of --emulate. Other --emulate interactions mock out
non-flashrom interactions, so need to continue handling --emulate
specially for now.

Switch --emulate to use the dummy programmer. Add an extra field to
store the original programmer option for deciding on whether the apply
the preserve_me quirk.

BUG=b:253966060
TEST=unit tests
BRANCH=None

Signed-off-by: Sam McNally <sammc@chromium.org>
Change-Id: I687749523f54edcb9dd41cfc85614949b9d6607a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/3965582
Reviewed-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>

4 files changed, 31 insertions, 68 deletions

diff --git a/futility/updater.c b/futility/updater.c
index 66529fea..51418847 100644
--- a/futility/updater.c
+++ b/futility/updater.c
@@ -7,6 +7,7 @@
 
 #include <assert.h>
 #include <ctype.h>
+#include <sys/stat.h>
 
 #include "2rsa.h"
 #include "crossystem.h"
@@ -463,7 +464,7 @@ static int preserve_management_engine(struct updater_config *cfg,
 				image_from, image_to, FMAP_SI_DESC);
 	}
 
-	if (!strcmp(image_from->programmer, PROG_HOST)) {
+	if (!strcmp(cfg->original_programmer, PROG_HOST)) {
 		if (try_apply_quirk(QUIRK_PRESERVE_ME, cfg) > 0) {
 			VB2_DEBUG("ME needs to be preserved - preserving %s.\n",
 				  FMAP_SI_ME);
@@ -1279,6 +1280,7 @@ struct updater_config *updater_new_config(void)
 		return cfg;
 	cfg->image.programmer = PROG_HOST;
 	cfg->image_current.programmer = PROG_HOST;
+	cfg->original_programmer = PROG_HOST;
 	cfg->ec_image.programmer = PROG_EC;
 	cfg->pd_image.programmer = PROG_PD;
 
@@ -1547,9 +1549,31 @@ int updater_setup_config(struct updater_config *cfg,
 		check_single_image = 1;
 		cfg->image.programmer = arg->programmer;
 		cfg->image_current.programmer = arg->programmer;
+		cfg->original_programmer = arg->programmer;
 		VB2_DEBUG("AP (host) programmer changed to %s.\n",
 			  arg->programmer);
 	}
+	if (arg->emulation) {
+		VB2_DEBUG("Using file %s for emulation.\n", arg->emulation);
+		check_single_image = 1;
+		struct stat statbuf;
+		if (stat(arg->emulation, &statbuf)) {
+			ERROR("Failed to stat emulation file %s\n",
+			      arg->emulation);
+			return ++errorcnt;
+		}
+
+		cfg->emulation = arg->emulation;
+		/* Store ownership of the dummy programmer string in
+		   cfg->emulation_programmer. */
+		ASPRINTF(&cfg->emulation_programmer,
+			 "dummy:emulate=VARIABLE_SIZE,size=%d,image=%s",
+			 (int)statbuf.st_size, arg->emulation);
+
+		cfg->image.programmer = cfg->emulation_programmer;
+		cfg->image_current.programmer = cfg->emulation_programmer;
+	}
+
 	if (arg->sys_props)
 		override_properties_from_list(arg->sys_props, cfg);
 	if (arg->write_protection) {
@@ -1560,14 +1584,6 @@ int updater_setup_config(struct updater_config *cfg,
 	}
 
 	/* Set up archive and load images. */
-	if (arg->emulation) {
-		/* Process emulation file first. */
-		cfg->emulation = arg->emulation;
-		VB2_DEBUG("Using file %s for emulation.\n", arg->emulation);
-		errorcnt += !!load_firmware_image(
-				&cfg->image_current, arg->emulation, NULL);
-	}
-
 	/* Always load images specified from command line directly. */
 	errorcnt += updater_load_images(
 			cfg, arg, arg->image, arg->ec_image, arg->pd_image);
@@ -1689,6 +1705,9 @@ void updater_delete_config(struct updater_config *cfg)
 	free_firmware_image(&cfg->image_current);
 	free_firmware_image(&cfg->ec_image);
 	free_firmware_image(&cfg->pd_image);
+	cfg->image.programmer = cfg->original_programmer;
+	cfg->image_current.programmer = cfg->original_programmer;
+	free(cfg->emulation_programmer);
 	remove_all_temp_files(&cfg->tempfiles);
 	if (cfg->archive)
 		archive_close(cfg->archive);
diff --git a/futility/updater.h b/futility/updater.h
index e526db87..08564b58 100644
--- a/futility/updater.h
+++ b/futility/updater.h
@@ -77,6 +77,8 @@ struct updater_config {
 	int do_verify;
 	int verbosity;
 	const char *emulation;
+	char *emulation_programmer;
+	const char *original_programmer;
 	int override_gbb_flags;
 	uint32_t gbb_flags;
 };
diff --git a/futility/updater_utils.c b/futility/updater_utils.c
index af94690a..a41c4038 100644
--- a/futility/updater_utils.c
+++ b/futility/updater_utils.c
@@ -618,61 +618,6 @@ static char *get_flashrom_command(enum flash_command flash_cmd,
 	return cmd;
 }
 
-/*
- * Emulates writing a firmware image to the system.
- * Returns 0 if success, non-zero if error.
- */
-static int emulate_write_firmware(const char *filename,
-				  const struct firmware_image *image,
-				  const char * const sections[])
-{
-	int i, errorcnt = 0;
-	struct firmware_image to_image = {0};
-
-	INFO("Writing from %s to %s (emu=%s).\n",
-	     image->file_name, image->programmer, filename);
-
-	if (load_firmware_image(&to_image, filename, NULL)) {
-		ERROR("Cannot load image from %s.\n", filename);
-		return -1;
-	}
-
-	if (image->size != to_image.size) {
-		ERROR("Image size is different (%s:%d != %s:%d)\n",
-		      image->file_name, image->size, to_image.file_name,
-		      to_image.size);
-		errorcnt++;
-		goto exit;
-	}
-
-	if (!sections) {
-		VB2_DEBUG(" - write the whole image.\n");
-		memmove(to_image.data, image->data, image->size);
-	}
-	for (i = 0; sections && sections[i]; i++) {
-		VB2_DEBUG(" - write the section: %s.\n", sections[i]);
-		if (preserve_firmware_section(image, &to_image, sections[i])) {
-			ERROR("Failed to write the section: %s\n", sections[i]);
-			errorcnt++;
-			/*
-			 * Exit the loop, but still write the file to reflect
-			 * the partial changes - same as real flashrom behavior.
-			 */
-			break;
-		}
-	}
-
-	if (vb2_write_file(filename, to_image.data, to_image.size)) {
-		ERROR("Failed writing to file: %s\n", filename);
-		errorcnt++;
-		goto exit;
-	}
-
-exit:
-	free_firmware_image(&to_image);
-	return errorcnt;
-}
-
 static int external_flashrom(enum flash_command flash_cmd,
 			     struct flashrom_params *params,
 			     struct tempfile *tempfiles)
@@ -796,9 +741,6 @@ int write_system_firmware(struct updater_config *cfg,
 	struct flashrom_params params = {0};
 	struct firmware_image *flash_contents = NULL;
 
-	if (cfg->emulation)
-		return emulate_write_firmware(cfg->emulation, image, sections);
-
 	if (cfg->use_diff_image && cfg->image_current.data &&
 	    is_the_same_programmer(&cfg->image_current, image))
 		flash_contents = &cfg->image_current;
diff --git a/tests/futility/test_update.sh b/tests/futility/test_update.sh
index e71a2a35..f2ca3034 100755
--- a/tests/futility/test_update.sh
+++ b/tests/futility/test_update.sh
@@ -334,7 +334,7 @@ test_update "Legacy update" \
 
 # Test quirks
 test_update "Full update (wrong size)" \
-	"${FROM_IMAGE}.large" "!Image size is different" \
+	"${FROM_IMAGE}.large" "!Failed writing firmware" \
 	-i "${TO_IMAGE}" --wp=0 --sys_props 0,0x10001,1 \
 	--quirks unlock_me_for_update,eve_smm_store