klibc - Jan 2019 - [klibc:master] Add support for reboot syscall argument

Commit-ID:  6b621b8705ce5901dcf49607c8a3523c9e521901
Gitweb:    
http://git.kernel.org/?p=libs/klibc/klibc.git;a=commit;h=6b621b8705ce5901dcf49607c8a3523c9e521901
Author:     Alfonso Sanchez-beato <alfonso.sanchez-beato at canonical.com>
AuthorDate: Wed, 31 May 2017 08:34:04 +0200
Committer:  Ben Hutchings <ben at decadent.org.uk>
CommitDate: Wed, 2 Jan 2019 03:06:15 +0000

[klibc] Add support for reboot syscall argument

Add support to the reboot command so an argument for the 4th parameter
of the syscall can be passed around. This can be useful in, say, devices
that follow Android partitions conventions, so we can do things like
rebootinig to the kernel in recovery partition with "reboot recovery".

References: https://bugs.launchpad.net/ubuntu/+source/klibc/+bug/1692494
Link: https://www.zytor.com/pipermail/klibc/2017-May/003957.html
Link: https://bugs.debian.org/863761
Signed-off-by: Ben Hutchings <ben at decadent.org.uk>

---
 usr/include/sys/reboot.h |  4 ++--
 usr/klibc/reboot.c       |  6 +++---
 usr/utils/halt.c         | 34 ++++++++++++++++++++--------------
 3 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/usr/include/sys/reboot.h b/usr/include/sys/reboot.h
index 3337d27..b46a1c5 100644
--- a/usr/include/sys/reboot.h
+++ b/usr/include/sys/reboot.h
@@ -16,8 +16,8 @@
 #define RB_DISABLE_CAD	LINUX_REBOOT_CMD_CAD_OFF
 #define RB_POWER_OFF	LINUX_REBOOT_CMD_POWER_OFF
 
-/* glibc-ish one-argument version */
-__extern int reboot(int);
+/* two-arguments version of reboot */
+__extern int reboot(int, void *);
 
 /* Native four-argument system call */
 __extern int __reboot(int, int, int, void *);
diff --git a/usr/klibc/reboot.c b/usr/klibc/reboot.c
index 5795dc3..5aab039 100644
--- a/usr/klibc/reboot.c
+++ b/usr/klibc/reboot.c
@@ -6,10 +6,10 @@
 #include <sys/reboot.h>
 #include <sys/syscall.h>
 
-/* This provides the one-argument glibc-ish version of reboot.
+/* This provides two-argument reboot function (glibc flag plus reboot
argument).
    The full four-argument system call is available as __reboot(). */
 
-int reboot(int flag)
+int reboot(int flag, void *arg)
 {
-	return __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, flag, NULL);
+	return __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, flag, arg);
 }
diff --git a/usr/utils/halt.c b/usr/utils/halt.c
index eed0a46..368f095 100644
--- a/usr/utils/halt.c
+++ b/usr/utils/halt.c
@@ -6,7 +6,7 @@
 
 static __noreturn usage(void)
 {
-	static char mesg[] = "Usage: {halt|reboot|poweroff} [-n]\n";
+	static char mesg[] = "Usage: {halt|reboot|poweroff} [-n]
[reboot-arg]\n";
 	write(2, mesg, sizeof(mesg) - 1);
 	exit(1);
 }
@@ -16,6 +16,7 @@ int main(int argc, char *argv[])
 	int cmd = 0; /* initalize to shut gcc up */
 	int do_sync = 1;
 	char *ptr, *ptr2;
+	char *reboot_arg = NULL;
 
 	/* Which action (program name)? */
 	ptr2 = ptr = argv[0];
@@ -32,23 +33,28 @@ int main(int argc, char *argv[])
 		usage();
 
 	/* Walk options */
-	while (*++argv && **argv == '-')
-		switch (*++*argv) {
-		case 'f':
-			break; /* -f assumed */
-		case 'n':
-			do_sync = 0;
-			break;
-		default:
-			usage();
+	while (*++argv)
+		if (**argv == '-') {
+			switch (*++*argv) {
+			case 'f':
+				break; /* -f assumed */
+			case 'n':
+				do_sync = 0;
+				break;
+			default:
+				usage();
+			}
+		} else if (cmd == LINUX_REBOOT_CMD_RESTART) {
+			reboot_arg = *argv;
+			cmd = LINUX_REBOOT_CMD_RESTART2;
+		} else {
+			usage(); /* args, not reboot == error */
 		}
-	if (*argv)
-		usage(); /* any args == error */
 
 	if (do_sync)
 		sync();
-	reboot(LINUX_REBOOT_CMD_CAD_OFF); /* Enable CTRL+ALT+DEL */
-	if (!reboot(cmd)) {
+	reboot(LINUX_REBOOT_CMD_CAD_OFF, NULL); /* Enable CTRL+ALT+DEL */
+	if (!reboot(cmd, reboot_arg)) {
 		/* Success. Currently, CMD_HALT returns, so stop the world */
 		/* kill(-1, SIGSTOP); */
 		kill(getpid(), SIGSTOP);