[PATCH v2 4/5] commands: create createnv command

[Sascha Hauer <s.hauer@pengutronix.de>]

We want to move away from describing the barebox environment explicitly
in the device tree and instead motivate usage of GPT partitions for the
envrionment. This patch creates a createnv command to facilitate this.
It creates an environment partition on the specified device and if
necessary also a GPT partition table. In the simplest case a "createnv"
without arguments will create a partition on the device barebox itself
booted from. Both the device and the size of the partition can be
specified on the command line.

We can't create environment partitions on a device containing a MBR
partition table, so a MBR partitioned device won't be touched.

As an additional safety net the command will ask the user if altering
the partition table is really desired. This behaviour can be overwritten
by specifying -f on the command line.

Link: https://lore.barebox.org/20250602-createnv-v1-4-c3239ff875d5@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 commands/Kconfig    |  18 ++++++
 commands/Makefile   |   1 +
 commands/createnv.c | 179 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 198 insertions(+)

diff --git a/commands/Kconfig b/commands/Kconfig
index 7145c9be952ebef2c9c75c6ddb65014e9c4247fe..23cb6d6b7832f146a4bd2eebf2b5bf8ae93692de 100644
--- a/commands/Kconfig
+++ b/commands/Kconfig
@@ -771,6 +771,24 @@ endmenu
 
 menu "Environment"
 
+config CMD_CREATENV
+	tristate
+	depends on PARTITION_DISK_EFI
+	select PARTITION_MANIPULATION
+	prompt "createnv"
+	help
+	  createnv - Create a barebox environment partition
+
+	  Usage: createnv [-sf] [device]
+
+	  Create a barebox environment partition.
+	  This creates a barebox environment partition and eventually
+	  a GPT partition table when it does not exist.
+
+	  Options:
+		-s <size>       specify partition size (default 1MiB)
+		-f      force. Do not ask
+
 config CMD_NV
 	depends on NVVAR
 	tristate
diff --git a/commands/Makefile b/commands/Makefile
index 603e1a25244cc8a6163128a5cc4c134a9552fa11..9247287ed53aa3bf06692744bf409e80bc832e7a 100644
--- a/commands/Makefile
+++ b/commands/Makefile
@@ -159,6 +159,7 @@ obj-$(CONFIG_CMD_UBSAN)		+= ubsan.o
 obj-$(CONFIG_CMD_SELFTEST)	+= selftest.o
 obj-$(CONFIG_CMD_FUZZ)		+= fuzz.o
 obj-$(CONFIG_CMD_TUTORIAL)	+= tutorial.o
+obj-$(CONFIG_CMD_CREATENV)	+= createnv.o
 obj-$(CONFIG_CMD_STACKSMASH)	+= stacksmash.o
 obj-$(CONFIG_CMD_PARTED)	+= parted.o
 obj-$(CONFIG_CMD_EFI_HANDLE_DUMP)	+= efi_handle_dump.o
diff --git a/commands/createnv.c b/commands/createnv.c
new file mode 100644
index 0000000000000000000000000000000000000000..df03664be11251165287bd2291d09bee7408f553
--- /dev/null
+++ b/commands/createnv.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <command.h>
+#include <malloc.h>
+#include <stdlib.h>
+#include <partitions.h>
+#include <driver.h>
+#include <disks.h>
+#include <xfuncs.h>
+#include <getopt.h>
+#include <efi/partition.h>
+#include <bootsource.h>
+#include <linux/kstrtox.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <envfs.h>
+
+static int do_createnv(int argc, char *argv[])
+{
+	uint64_t start, size = SZ_1M;
+	struct cdev *cdev;
+	struct block_device *blk;
+	struct partition *part;
+	struct partition_desc *pdesc = NULL;
+	enum filetype filetype;
+	guid_t partition_barebox_env_guid = PARTITION_BAREBOX_ENVIRONMENT_GUID;
+	void *buf = NULL;
+	bool force = false;
+	int opt, ret;
+
+	while ((opt = getopt(argc, argv, "s:f")) > 0) {
+		switch (opt) {
+		case 's':
+			size = strtoull_suffix(optarg, NULL, 0);
+			break;
+		case 'f':
+			force = true;
+			break;
+		default:
+			return COMMAND_ERROR_USAGE;
+		}
+        }
+
+	argc -= optind;
+	argv += optind;
+
+	if (argc < 1) {
+		cdev = bootsource_of_cdev_find();
+		if (!cdev) {
+			printf("Cannot find bootsource cdev\n");
+			return COMMAND_ERROR;
+		}
+		ret = cdev_open(cdev, O_RDWR);
+		if (ret) {
+			printf("Cannot open %s: %pe\n", cdev->name, ERR_PTR(ret));
+			return COMMAND_ERROR;
+		}
+	} else {
+		cdev = cdev_open_by_path_name(argv[0], O_RDWR);
+		if (!cdev) {
+			printf("Cannot open %s\n", argv[0]);
+			return COMMAND_ERROR;
+		}
+	}
+
+	blk = cdev_get_block_device(cdev);
+	if (!blk) {
+		ret = -ENOENT;
+		goto err;
+	}
+
+	buf = xzalloc(2 * SECTOR_SIZE);
+
+	ret = cdev_read(cdev, buf, 2 * SECTOR_SIZE, 0, 0);
+	if (ret < 0) {
+		printf("Cannot read from %s: %pe\n", cdev->name, ERR_PTR(ret));
+		goto err;
+	}
+
+	filetype = file_detect_partition_table(buf, 2 * SECTOR_SIZE);
+
+	switch (filetype) {
+	case filetype_gpt:
+		pdesc = partition_table_read(blk);
+		if (!pdesc) {
+			printf("Cannot read partition table\n");
+			ret = -EINVAL;
+			goto err;
+		}
+		break;
+	case filetype_mbr:
+		printf("%s contains a DOS partition table. Cannot create a barebox environment here\n",
+		       cdev->name);
+		ret = -EINVAL;
+		goto err;
+	default:
+		printf("Will create a GPT on %s\n", cdev->name);
+		pdesc = partition_table_new(blk, "gpt");
+		break;
+	}
+
+	list_for_each_entry(part, &pdesc->partitions, list) {
+		if (guid_equal(&part->typeuuid, &partition_barebox_env_guid)) {
+			printf("%s already contains a barebox environment partition\n",
+			       cdev->name);
+			ret = -EINVAL;
+			goto err;
+		}
+	}
+
+	size >>= SECTOR_SHIFT;
+
+	ret = partition_find_free_space(pdesc, size, &start);
+	if (ret) {
+		printf("No free space available\n");
+		goto err;
+	}
+
+	ret = partition_create(pdesc, "barebox-environment", "bbenv", start, start + size - 1);
+	if (ret) {
+		printf("Creating partition failed: %pe\n", ERR_PTR(ret));
+		goto err;
+	}
+
+	printf("Will create a barebox environment partition of size %llu bytes on %s\n",
+	       size << SECTOR_SHIFT, cdev->name);
+
+	if (!force) {
+		char c;
+
+		printf("Do you wish to continue? (y/n)\n");
+
+		c = getchar();
+		if (c != 'y') {
+			ret = -EINTR;
+			goto err;
+		}
+	}
+
+	ret = partition_table_write(pdesc);
+	if (ret) {
+		printf("Cannot write partition table: %pe\n", ERR_PTR(ret));
+		goto err;
+	}
+
+	if (!default_environment_path_get()) {
+		char *path = xasprintf("/dev/%s.barebox-environment", cdev->name);
+		default_environment_path_set(path);
+		free(path);
+	}
+
+	printf("Created barebox environment partition on %s\n", cdev->name);
+
+	ret = 0;
+err:
+	if (pdesc)
+		partition_table_free(pdesc);
+
+	free(buf);
+	cdev_close(cdev);
+
+	return ret ? COMMAND_ERROR : 0;
+}
+
+BAREBOX_CMD_HELP_START(createnv)
+BAREBOX_CMD_HELP_TEXT("Create a barebox environment partition.")
+BAREBOX_CMD_HELP_TEXT("This creates a barebox environment partition and eventually")
+BAREBOX_CMD_HELP_TEXT("a GPT partition table when it does not exist.")
+BAREBOX_CMD_HELP_OPT("-s <size>", "specify partition size (default 1MiB)")
+BAREBOX_CMD_HELP_OPT("-f\t", "force. Do not ask")
+BAREBOX_CMD_HELP_END
+
+BAREBOX_CMD_START(createnv)
+        .cmd            = do_createnv,
+        BAREBOX_CMD_DESC("Create a barebox environment partition")
+        BAREBOX_CMD_OPTS("[-sf] [device]")
+        BAREBOX_CMD_GROUP(CMD_GRP_CONSOLE)
+        BAREBOX_CMD_HELP(cmd_createnv_help)
+BAREBOX_CMD_END

-- 
2.39.5