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authorGravatar Denys Vlasenko <vda.linux@googlemail.com>2018-04-20 15:12:52 +0200
committerGravatar Denys Vlasenko <vda.linux@googlemail.com>2018-04-20 15:12:52 +0200
commitc21dfaf836cf0eb5317035bc20395c751a205934 (patch)
tree1b9b812eb0153da450a7f9f14fd444dc0bc4b567 /examples/shutdown-1.0/script/hardshutdown.c
parente09c426456cfd030cc868d93bbcb2e0a6933cabb (diff)
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examples/shutdown-1.0: an example of reboot which does not signal init
For one, my inits know nothing about the concept of "shutting down the system". Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'examples/shutdown-1.0/script/hardshutdown.c')
-rw-r--r--examples/shutdown-1.0/script/hardshutdown.c168
1 files changed, 168 insertions, 0 deletions
diff --git a/examples/shutdown-1.0/script/hardshutdown.c b/examples/shutdown-1.0/script/hardshutdown.c
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+++ b/examples/shutdown-1.0/script/hardshutdown.c
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+/* Including <unistd.h> makes sure that on a glibc system
+ * <features.h> is included, which again defines __GLIBC__
+ */
+
+#include <unistd.h>
+#include <stdio.h> /* puts */
+#include <time.h> /* nanosleep */
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+/*
+ * Magic values required to use _reboot() system call.
+ */
+#define LINUX_REBOOT_MAGIC1 0xfee1dead
+#define LINUX_REBOOT_MAGIC2 672274793
+#define LINUX_REBOOT_MAGIC2A 85072278
+#define LINUX_REBOOT_MAGIC2B 369367448
+/*
+ * Commands accepted by the _reboot() system call.
+ *
+ * RESTART Restart system using default command and mode.
+ * HALT Stop OS and give system control to ROM monitor, if any.
+ * CAD_ON Ctrl-Alt-Del sequence causes RESTART command.
+ * CAD_OFF Ctrl-Alt-Del sequence sends SIGINT to init task.
+ * POWER_OFF Stop OS and remove all power from system, if possible.
+ * RESTART2 Restart system using given command string.
+ */
+#define LINUX_REBOOT_CMD_RESTART 0x01234567
+#define LINUX_REBOOT_CMD_HALT 0xCDEF0123
+#define LINUX_REBOOT_CMD_CAD_ON 0x89ABCDEF
+#define LINUX_REBOOT_CMD_CAD_OFF 0x00000000
+#define LINUX_REBOOT_CMD_POWER_OFF 0x4321FEDC
+#define LINUX_REBOOT_CMD_RESTART2 0xA1B2C3D4
+
+
+#define USE_LIBC
+
+#ifdef USE_LIBC
+
+/* libc version */
+#if defined __GLIBC__ && __GLIBC__ >= 2
+# include <sys/reboot.h>
+# define REBOOT(cmd) reboot(cmd)
+#else
+extern int reboot(int, int, int);
+# define REBOOT(cmd) reboot(LINUX_REBOOT_MAGIC1,LINUX_REBOOT_MAGIC2,(cmd))
+#endif
+
+static int my_reboot(int cmd)
+{
+ return REBOOT(cmd);
+}
+
+#else /* no USE_LIBC */
+
+/* direct syscall version */
+#include <linux/unistd.h>
+
+#ifdef _syscall3
+_syscall3(int, reboot, int, magic, int, magic_too, int, cmd);
+#else
+/* Let us hope we have a 3-argument reboot here */
+extern int reboot(int, int, int);
+#endif
+
+static int my_reboot(int cmd)
+{
+ return reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, cmd);
+}
+
+#endif
+
+
+static void do_reboot(void)
+{
+ my_reboot(LINUX_REBOOT_CMD_RESTART);
+}
+static void do_poweroff(void)
+{
+ my_reboot(LINUX_REBOOT_CMD_POWER_OFF);
+}
+static void do_halt(void)
+{
+ my_reboot(LINUX_REBOOT_CMD_HALT);
+}
+
+static void usage(void)
+{
+ puts(
+ "Usage: hardshutdown -h|-r|-p [NN]\n"
+ " NN - seconds to sleep before requested action"
+ );
+ exit(1);
+}
+
+enum action_t {
+ SHUTDOWN, // do nothing
+ HALT,
+ POWEROFF,
+ REBOOT
+};
+
+int main(int argc, char *argv[])
+{
+ struct timespec t = {0,0};
+ enum action_t action = SHUTDOWN;
+ int c, i;
+ char *prog, *ptr;
+
+ //if (*argv[0] == '-') argv[0]++; /* allow shutdown as login shell */
+ prog = argv[0];
+ ptr = strrchr(prog,'/');
+ if (ptr)
+ prog = ptr+1;
+
+ for (c=1; c < argc; c++) {
+ if (argv[c][0] >= '0' && argv[c][0] <= '9') {
+ t.tv_sec = strtol(argv[c], NULL, 10);
+ continue;
+ }
+ if (argv[c][0] != '-') {
+ usage();
+ return 1;
+ }
+ for (i=1; argv[c][i]; i++) {
+ switch (argv[c][i]) {
+ case 'h':
+ action = HALT;
+ break;
+ case 'p':
+ action = POWEROFF;
+ break;
+ case 'r':
+ action = REBOOT;
+ break;
+ default:
+ usage();
+ return 1;
+ }
+ }
+ }
+
+ if (action==SHUTDOWN) {
+ usage();
+ return 1;
+ }
+
+ chdir("/");
+ while (nanosleep(&t,&t)<0)
+ if (errno!=EINTR) break;
+
+ switch (action) {
+ case HALT:
+ do_halt();
+ break;
+ case POWEROFF:
+ do_poweroff();
+ break;
+ case REBOOT:
+ do_reboot();
+ break;
+ default: /* SHUTDOWN */
+ break;
+ }
+ return 1;
+}