From 86bb84d57695fbe94455259014edeb5aacec13f4 Mon Sep 17 00:00:00 2001
From: Warner Losh <imp@FreeBSD.org>
Date: Fri, 26 Jan 2018 17:13:00 +0000
Subject: [PATCH] Split panic routine

Split panic routine so that the 'Hit Any Key to continue' behavior can
be overriden.

Sponsored by: Netflix
---
 stand/i386/gptboot/gptboot.c |  2 +-
 stand/libsa/panic.c          | 19 +++++++++++++------
 stand/libsa/stand.h          |  4 ++--
 3 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/stand/i386/gptboot/gptboot.c b/stand/i386/gptboot/gptboot.c
index 49c2d5f82c54..40fa00e59279 100644
--- a/stand/i386/gptboot/gptboot.c
+++ b/stand/i386/gptboot/gptboot.c
@@ -102,7 +102,6 @@ static struct bios_smap smap;
 static char *heap_next;
 static char *heap_end;
 
-void exit(int);
 static void load(void);
 static int parse_cmds(char *, int *);
 static int dskread(void *, daddr_t, unsigned);
@@ -365,6 +364,7 @@ main(void)
 void
 exit(int x)
 {
+	while (1);
 }
 
 static void
diff --git a/stand/libsa/panic.c b/stand/libsa/panic.c
index 6e4c76d0e031..bc6e7e2aca5a 100644
--- a/stand/libsa/panic.c
+++ b/stand/libsa/panic.c
@@ -39,7 +39,18 @@ __FBSDID("$FreeBSD$");
 #include <stand.h>
 #include <machine/stdarg.h>
 
-extern void exit(int) __dead2;
+/*
+ * Boot loaders and other standalone programs that wish to have a
+ * different panic policy can provide their own panic_action rotuine.
+ */
+__weak_symbol void
+panic_action(void)
+{
+	printf("--> Press a key on the console to reboot <--\n");
+	getchar();
+	printf("Rebooting...\n");
+	exit(1);
+}
 
 void
 panic(const char *fmt,...)
@@ -51,9 +62,5 @@ panic(const char *fmt,...)
 	vprintf(fmt, ap);
 	va_end(ap);
 	printf("\n");
-
-	printf("--> Press a key on the console to reboot <--\n");
-	getchar();
-	printf("Rebooting...\n");
-	exit(1);
+	panic_action();
 }
diff --git a/stand/libsa/stand.h b/stand/libsa/stand.h
index c867f7a05635..7c93f83af56b 100644
--- a/stand/libsa/stand.h
+++ b/stand/libsa/stand.h
@@ -368,7 +368,6 @@ static __inline quad_t qmin(quad_t a, quad_t b) { return (a < b ? a : b); }
 static __inline u_long ulmax(u_long a, u_long b) { return (a > b ? a : b); }
 static __inline u_long ulmin(u_long a, u_long b) { return (a < b ? a : b); }
 
-
 /* null functions for device/filesystem switches (undocumented) */
 extern int	nodev(void);
 extern int	noioctl(struct open_file *, u_long, void *);
@@ -387,13 +386,14 @@ extern int	null_readdir(struct open_file *f, struct dirent *d);
  * Machine dependent functions and data, must be provided or stubbed by 
  * the consumer 
  */
-extern void		exit(int);
+extern void		exit(int) __dead2;
 extern int		getchar(void);
 extern int		ischar(void);
 extern void		putchar(int);
 extern int		devopen(struct open_file *, const char *, const char **);
 extern int		devclose(struct open_file *f);
 extern void		panic(const char *, ...) __dead2 __printflike(1, 2);
+extern void		panic_action(void) __weak_symbol __dead2;
 extern time_t		getsecs(void);
 extern struct fs_ops	*file_system[];
 extern struct fs_ops	*exclusive_file_system;