[PATCH RFC] bootm: support printing bootm parameters determined at runtime to file

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

The barebox bootm command is often not called directly, but via
bootloader spec or FIT image boot handlers. For debugging, it can be
useful to reuse those boot handlers, but replace single artifacts, e.g.
using the barebox device tree instead of the bootloader-spec provided
device tree.

To make this easier, have boot -v -d (verbose + dry run) write a boot
script that reproduces the cancelled boot to /env/boot/cancelled.

The user can then edit the file and boot it manually.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 commands/bootm.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++
 common/bootm.c   | 10 +++++-
 include/bootm.h  |  9 +++++
 3 files changed, 103 insertions(+), 1 deletion(-)

diff --git a/commands/bootm.c b/commands/bootm.c
index 95d267135cdb..520f041b6bac 100644
--- a/commands/bootm.c
+++ b/commands/bootm.c
@@ -8,6 +8,7 @@
 #include <driver.h>
 #include <command.h>
 #include <image.h>
+#include <boot.h>
 #include <malloc.h>
 #include <environment.h>
 #include <asm/byteorder.h>
@@ -36,6 +37,90 @@
 #define BOOTM_OPTS BOOTM_OPTS_COMMON
 #endif
 
+int bootm_print_cmd(const char *file, const struct bootm_data *data)
+{
+	int fd = CONSOLE_STDOUT;
+	const char *bootargs;
+	const char *verify = "";
+
+	if (!IS_ENABLED(CONFIG_GLOBALVAR))
+		return -ENOSYS;
+
+	if (file) {
+		fd = creat(file, 0755);
+		if (fd < 0)
+			return fd;
+	}
+
+	dprintf(fd, "#!/bin/sh\n\n");
+
+	if (data->appendroot)
+		dprintf(fd, "global.bootm.appendroot=%u\n", data->appendroot);
+	if (data->root_dev)
+		dprintf(fd, "global.bootm.root_dev='%s'\n", data->root_dev);
+	if (data->provide_machine_id)
+		dprintf(fd, "global.bootm.machine_id=%u\n", data->provide_machine_id);
+
+	switch (data->verify) {
+	case BOOTM_VERIFY_NONE:
+		verify = "none";
+		break;
+	case BOOTM_VERIFY_HASH:
+		verify = "hash";
+		break;
+	case BOOTM_VERIFY_AVAILABLE:
+		verify = "available";
+		break;
+	case BOOTM_VERIFY_SIGNATURE:
+		verify = "signature";
+		break;
+	}
+
+	dprintf(fd, "global.bootm.verify=%s\n", verify);
+
+	dprintf(fd, "\n");
+
+	if (data->os_address != UIMAGE_SOME_ADDRESS)
+		dprintf(fd, "global.bootm.image.loadaddr=0x%08lx\n", data->os_address);
+	if (data->os_file)
+		dprintf(fd, "global.bootm.image='%s'\n", data->os_file);
+	if (data->oftree_file)
+		dprintf(fd, "global.bootm.oftree='%s'\n", data->oftree_file);
+#ifdef CONFIG_BOOTM_INITRD
+	if (data->initrd_file)
+		dprintf(fd, "global.bootm.initrd='%s'\n", data->initrd_file);
+
+	if (data->initrd_address != UIMAGE_INVALID_ADDRESS)
+		dprintf(fd, "global.bootm.initrd.loadaddr=0x%08lx\n", data->initrd_address);
+#endif
+	if (data->tee_file)
+		dprintf(fd, "global.bootm.tee_file='%s'\n", data->tee_file);
+
+	dprintf(fd, "\n");
+
+	bootargs = linux_bootargs_get();
+	if (bootargs)
+		dprintf(fd, "global linux.bootargs.dyn.concatenated='%s'\n", bootargs);
+
+	if (data->force || data->os_entry != UIMAGE_SOME_ADDRESS) {
+		/* We have no global variables for these two parameters yet, so
+		 * we just print a comment to alert the user to this fact
+		 */
+
+		dprintf(fd, "\n# bootm ");
+		if (data->force)
+				dprintf(fd, "-f ");
+		if (data->os_entry != UIMAGE_SOME_ADDRESS)
+				dprintf(fd, "-e %08lx ", data->os_entry);
+		dputc(fd, '\n');
+	}
+
+	if (file)
+		close(fd);
+
+	return 0;
+}
+
 static int do_bootm(int argc, char *argv[])
 {
 	int opt;
diff --git a/common/bootm.c b/common/bootm.c
index 29ea13e28cb8..3ecd788e7b16 100644
--- a/common/bootm.c
+++ b/common/bootm.c
@@ -825,8 +825,16 @@ int bootm_boot(struct bootm_data *bootm_data)
 	}
 
 	ret = handler->bootm(data);
-	if (data->dryrun)
+	if (data->dryrun) {
 		pr_info("Dryrun. Aborted\n");
+		if (bootm_verbose(data)) {
+			const char *file = "/env/boot/cancelled";
+			if (!bootm_print_cmd(file, bootm_data))
+				pr_info("Boot script written to %s\n", file);
+			else
+				pr_warn("Boot script write to %s failed: %m\n", file);
+		}
+	}
 
 err_out:
 	if (data->os_res)
diff --git a/include/bootm.h b/include/bootm.h
index ee2b574521db..53d2905ca992 100644
--- a/include/bootm.h
+++ b/include/bootm.h
@@ -41,6 +41,15 @@ struct bootm_data {
 
 int bootm_boot(struct bootm_data *data);
 
+#ifdef CONFIG_CMD_BOOTM
+int bootm_print_cmd(const char *file, const struct bootm_data *data);
+#else
+static inline int bootm_print_cmd(const char *file, const struct bootm_data *data)
+{
+	return -ENOSYS;
+}
+#endif
+
 struct image_data {
 	/* simplest case. barebox has already loaded the os here */
 	struct resource *os_res;
-- 
2.39.2