Move boot to discover server

This change moves the boot-via-kexec functionality from the UIs to the
discover server.

On the UI side: rather than run kexec directly, we just send a message
to the discover server. Because this is generic discover client
functionality, we no longer need the boot callbacks in the twin- and
ncurses-specific code.

We also remove the kexec and URL-loading code from the UIs, and add it
to the discover server code, in paths.c. We expose this to the server
though a new function:

  load_path(void *, const char *, unsigned int *);

On the server side, we simply move hook up the boot() function to use
the load_file and kexec calls.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

1 files changed, 151 insertions, 6 deletions

diff --git a/discover/boot.c b/discover/boot.c
index ddb9e7d..6109562 100644
--- a/discover/boot.c
+++ b/discover/boot.c
@@ -1,14 +1,159 @@
 
+#include <assert.h>
+
+#include <log/log.h>
+#include <pb-protocol/pb-protocol.h>
+#include <system/system.h>
+#include <talloc/talloc.h>
+
 #include "boot.h"
+#include "paths.h"
+
+/**
+ * kexec_load - kexec load helper.
+ * @l_image: The local image file for kexec to execute.
+ * @l_initrd: Optional local initrd file for kexec --initrd, can be NULL.
+ * @args: Optional command line args for kexec --append, can be NULL.
+ */
+
+static int kexec_load(const char *l_image, const char *l_initrd,
+	const char *args, int dry_run)
+{
+	int result;
+	const char *argv[6];
+	const char **p;
+	char *s_initrd = NULL;
+	char *s_args = NULL;
+
+	p = argv;
+	*p++ = pb_system_apps.kexec;	/* 1 */
+	*p++ = "-l";			/* 2 */
+
+	if (l_initrd) {
+		s_initrd = talloc_asprintf(NULL, "--initrd=%s", l_initrd);
+		assert(s_initrd);
+		*p++ = s_initrd;	 /* 3 */
+	}
+
+	if (args) {
+		s_args = talloc_asprintf(NULL, "--append=%s", args);
+		assert(s_args);
+		*p++ = s_args;		/* 4 */
+	}
+
+	*p++ = l_image;			/* 5 */
+	*p++ = NULL;			/* 6 */
+
+	result = pb_run_cmd(argv, 1, dry_run);
+
+	if (result)
+		pb_log("%s: failed: (%d)\n", __func__, result);
+
+	talloc_free(s_initrd);
+	talloc_free(s_args);
+
+	return result;
+}
+
+/**
+ * kexec_reboot - Helper to boot the new kernel.
+ *
+ * Must only be called after a successful call to kexec_load().
+ */
+
+static int kexec_reboot(int dry_run)
+{
+	int result = 0;
+	const char *argv[4];
+	const char **p;
+
+	/* First try running shutdown.  Init scripts should run 'exec -e' */
+
+	p = argv;
+	*p++ = pb_system_apps.shutdown;	/* 1 */
+	*p++ =  "-r";			/* 2 */
+	*p++ =  "now";			/* 3 */
+	*p++ =  NULL;			/* 4 */
+
+	result = pb_run_cmd(argv, 1, dry_run);
+
+	/* On error, force a kexec with the -e option */
+
+	if (result) {
+		p = argv;
+		*p++ = pb_system_apps.kexec;	/* 1 */
+		*p++ = "-e";			/* 2 */
+		*p++ = NULL;			/* 3 */
+
+		result = pb_run_cmd(argv, 1, 0);
+	}
+
+	if (result)
+		pb_log("%s: failed: (%d)\n", __func__, result);
+
+	return result;
+}
 
 int boot(void *ctx, struct boot_option *opt, struct boot_command *cmd,
 		int dry_run)
 {
-	/* todo: run kexec with options from opt & cmd */
-	(void)ctx;
-	(void)opt;
-	(void)cmd;
-	(void)dry_run;
+	char *local_image, *local_initrd;
+	unsigned int clean_image = 0;
+	unsigned int clean_initrd = 0;
+	char *image, *initrd, *args;
+	int result;
+
+	image = NULL;
+	initrd = NULL;
+	args = NULL;
+
+	if (cmd->boot_image_file) {
+		image = talloc_strdup(ctx, cmd->boot_image_file);
+	} else if (opt && opt->boot_image_file) {
+		image = talloc_strdup(ctx, opt->boot_image_file);
+	} else {
+		pb_log("%s: no image specified", __func__);
+		return -1;
+	}
+
+	if (cmd->initrd_file) {
+		image = talloc_strdup(ctx, cmd->initrd_file);
+	} else if (opt && opt->initrd_file) {
+		image = talloc_strdup(ctx, opt->initrd_file);
+	}
+
+	if (cmd->boot_args) {
+		args = talloc_strdup(ctx, cmd->boot_args);
+	} else if (opt && opt->boot_args) {
+		args = talloc_strdup(ctx, opt->boot_args);
+	}
+
+	result = -1;
+
+	local_image = load_file(NULL, image, &clean_image);
+	if (!local_image)
+		goto no_load;
+
+	local_initrd = NULL;
+	if (initrd) {
+		local_initrd = load_file(NULL, initrd, &clean_initrd);
+		if (!local_initrd)
+			goto no_load;
+	}
+
+	result = kexec_load(local_image, local_initrd, args, dry_run);
+
+no_load:
+	if (clean_image)
+		unlink(local_image);
+	if (clean_initrd)
+		unlink(local_initrd);
+
+	talloc_free(local_image);
+	talloc_free(local_initrd);
+
+	if (!result)
+		result = kexec_reboot(dry_run);
 
-	return 0;
+	return result;
 }