fastboot: evaluate fastboot partitions when used

So far we have evaluated the fastboot partition description during
initialization of the fastboot gadget. Let's make this more flexible
and parse it when actually needed.
This gives us the possibility to first write an image including a
partition table to a disk and afterwards write an image to a single
partition created by the first whole disk write.

Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>
Link: https://lore.barebox.org/20240215074757.960200-8-s.hauer@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 32 insertions, 15 deletions

diff --git a/common/fastboot.c b/common/fastboot.c
index f41c02a576..f5a275d8bf 100644
--- a/common/fastboot.c
+++ b/common/fastboot.c
@@ -80,7 +80,7 @@ static struct fb_variable *fb_addvar(struct fastboot *fb, struct list_head *list
 	return var;
 }
 
-static int fastboot_add_partition_variables(struct fastboot *fb,
+static int fastboot_add_partition_variables(struct fastboot *fb, struct list_head *list,
 		struct file_list_entry *fentry)
 {
 	struct stat s;
@@ -152,9 +152,9 @@ out:
 	if (ret)
 		return ret;
 
-	var = fb_addvar(fb, &fb->variables, "partition-size:%s", fentry->name);
+	var = fb_addvar(fb, list, "partition-size:%s", fentry->name);
 	fb_setvar(var, "%08zx", size);
-	var = fb_addvar(fb, &fb->variables, "partition-type:%s", fentry->name);
+	var = fb_addvar(fb, list, "partition-type:%s", fentry->name);
 	fb_setvar(var, "%s", type);
 
 	return ret;
@@ -162,8 +162,6 @@ out:
 
 int fastboot_generic_init(struct fastboot *fb, bool export_bbu)
 {
-	int ret;
-	struct file_list_entry *fentry;
 	struct fb_variable *var;
 
 	INIT_LIST_HEAD(&fb->variables);
@@ -186,12 +184,6 @@ int fastboot_generic_init(struct fastboot *fb, bool export_bbu)
 	if (export_bbu)
 		bbu_append_handlers_to_file_list(fb->files);
 
-	file_list_for_each_entry(fb->files, fentry) {
-		ret = fastboot_add_partition_variables(fb, fentry);
-		if (ret)
-			return ret;
-	}
-
 	return 0;
 }
 
@@ -305,26 +297,51 @@ static int strcmp_l1(const char *s1, const char *s2)
 static void cb_getvar(struct fastboot *fb, const char *cmd)
 {
 	struct fb_variable *var;
+	LIST_HEAD(partition_list);
+	struct file_list_entry *fentry;
+
+	file_list_for_each_entry(fb->files, fentry) {
+		int ret;
+
+		ret = fastboot_add_partition_variables(fb, &partition_list, fentry);
+		if (ret) {
+			pr_warn("Failed to add partition variables: %pe", ERR_PTR(ret));
+			return;
+		}
+	}
 
 	pr_debug("getvar: \"%s\"\n", cmd);
 
 	if (!strcmp_l1(cmd, "all")) {
-		list_for_each_entry(var, &fb->variables, list) {
+		list_for_each_entry(var, &fb->variables, list)
 			fastboot_tx_print(fb, FASTBOOT_MSG_INFO, "%s: %s",
 					  var->name, var->value);
-		}
+
+		list_for_each_entry(var, &partition_list, list)
+			fastboot_tx_print(fb, FASTBOOT_MSG_INFO, "%s: %s",
+					  var->name, var->value);
+
 		fastboot_tx_print(fb, FASTBOOT_MSG_OKAY, "");
-		return;
+		goto out;
 	}
 
 	list_for_each_entry(var, &fb->variables, list) {
 		if (!strcmp(cmd, var->name)) {
 			fastboot_tx_print(fb, FASTBOOT_MSG_OKAY, var->value);
-			return;
+			goto out;
+		}
+	}
+
+	list_for_each_entry(var, &partition_list, list) {
+		if (!strcmp(cmd, var->name)) {
+			fastboot_tx_print(fb, FASTBOOT_MSG_OKAY, var->value);
+			goto out;
 		}
 	}
 
 	fastboot_tx_print(fb, FASTBOOT_MSG_OKAY, "");
+out:
+	fastboot_free_variables(&partition_list);
 }
 
 int fastboot_handle_download_data(struct fastboot *fb, const void *buffer,